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PURPOSE: The role of frailty in affecting survival in myelodysplastic syndromes (MDS) is increasingly recognized. Despite this, a paucity of data exists on the association between frailty and other clinically meaningful outcomes including health care resource utilization and costs of care. METHODS: We linked the Ontario subset of the prospective Canadian MDS registry (including baseline patient/disease characteristics) to population-based health system administrative databases. Baseline frailty was calculated from the 15-item MDS-specific frailty scale (FS-15). Primary outcomes were public health care utilization and 30-day standardized costs of care (2019 Canadian dollars) determined for each phase of disease (initial, continuation, and terminal phases). Negative binomial regression was used to assess the association between frailty and health care costs with Poisson regression to explore predictors of hospitalization. RESULTS: Among 461 patients with complete FS-15 scores, 374 (81.1%) had a hospitalization with a mean length of stay of 10.6 days. Controlling for age, comorbidities, Revised International Prognostic Scoring System, and transfusion dependence, the FS-15 was independently associated with hospitalization during the initial ( P = .02) and continuation ( P = .01) phases but not the terminal disease phase ( P = .09). The mean 30-day standardized cost per patient was $8,499 (median, $6,295; interquartile range, $2,798-$11,996), largely driven by cancer clinic visits and hospitalization. On multivariable analysis, the FS-15 was independently associated with costs of care during the initial disease phase ( P = .02). CONCLUSION: We demonstrate an association between frailty and clinically meaningful outcomes including hospitalization and costs of care in patients with MDS. Our results suggest that baseline frailty may help to inform patients and physicians of expected outcomes.

Iron overload (IO) reflected by elevated ferritin is associated with increased mortality in myelodysplastic syndromes (MDS), however, ferritin is an imperfect metric. Elevated labile plasma iron correlates with clinical outcomes and transferrin saturation (TSAT) >80%, but is not readily measurable. The trajectory of TSAT, and its association with clinical outcomes remain undefined. Canadian MDS registry patients were evaluated. Mean TSAT, mean ferritin and transfusion dose density (TDD) were determined. Survival was evaluated by TSAT and ferritin (80%), (≤500 μg/L, 501-800 μg/L, >800 μg/L). In 718 patients, median age was 74 years; 12%, 31%, 29%, 15% and 13% were IPSS-R very low, low, intermediate, high and very high. TSAT and ferritin were moderately correlated (r=0.63, P80% trended with inferior cardiac death-free survival (P=0.053). In univariate analysis, age, IPSS-R, blast percentage by Eastern Cooperative Oncology Group Performance Status, frailty, Charlson Comorbidity Index, iron chelation (Y/N), TDD, TSAT and ferritin were significantly associated with inferior OS. By multivariable analysis, TSAT >80% (P=0.007) remained significant for OS (R2 30.3%). In MDS, TSAT >80% and ferritin >800 μg/L portended inferior OS, PFS and LFS. TSAT may indicate the presence of oxidative stress, and is readily measurable in a clinical setting. The relationship between TSAT and cardiac death-free survival warrants further study.

Anti-apoptotic proteins such as BCL-XLpromote cell survival by sequestering pro-apoptotic BCL-2 family members, an activity that frequently contributes to tumorigenesis. Thus, the development of small-molecule inhibitors for anti-apoptotic proteins, termed BH3-mimetics, is revolutionizing how we treat cancer. BH3 mimetics kill cells by displacing sequestered pro-apoptotic proteins to initiate tumor-cell death. Recent evidence has demonstrated that in live cells the BH3-only proteins PUMA and BIM resist displacement by BH3-mimetics, while others like tBID do not. Analysis of the molecular mechanism by which PUMA resists BH3-mimetic mediated displacement from full-length anti-apoptotic proteins (BCL-XL, BCL-2, BCL-W and MCL-1) reveals that both the BH3-motif and a novel binding site within the carboxyl-terminal sequence (CTS) of PUMA contribute to binding. Together these sequences bind to anti-apoptotic proteins, which effectively “double-bolt locks” the proteins to resist BH3-mimetic displacement. The pro-apoptotic protein BIM has also been shown to double-bolt lock to anti-apoptotic proteins however, the novel binding sequence in PUMA is unrelated to that in the CTS of BIM and functions independent of PUMA binding to membranes. Moreover, contrary to previous reports, we find that when exogenously expressed, the CTS of PUMA directs the protein primarily to the endoplasmic reticulum (ER) rather than mitochondria and that residues I175 and P180 within the CTS are required for both ER localization and BH3-mimetic resistance. Understanding how PUMA resists BH3-mimetic displacement will be useful in designing more efficacious small-molecule inhibitors of anti-apoptotic BCL-2 proteins.

Many patients with lower-risk myelodysplastic syndromes (LR MDS) require long-term red blood cell (RBC) transfusions to manage anemia. The consequences of RBC transfusions in LR MDS with ring sideroblasts (LR MDS-RS) are not well known. We estimated the association between cumulative RBC dose density and clinical and patient-reported outcomes using data from the MDS-CAN registry for patients enrolled between January 2008 and December 2018. Outcomes included overall survival, hospitalization, and health-related quality of life (HRQoL). A total of 145 enrolled patients with LR MDS and RS ≥5% had a median follow-up time of 27.1 months; 45 had no transfusions during follow-up, 51 had1 transfusion per month, and 49 had ≥1 transfusion per month. The cumulative density of RBC transfusions was associated with significantly greater mortality, hospitalization, and inferior HRQoL, suggesting that exposure to RBC transfusion may constitute a significant treatment burden in patients with LR MDS-RS.

Background: Observational studies suggest an anti-neoplastic effect associated with statins, metformin, dipeptidyl peptidase-4 inhibitors (DPP4i), while sulfonylureas may have a neutral or detrimental effect. The aim of this study was to determine the impact of these medications in patients with myelodysplastic syndromes (MDS). Methods: A prospective Canadian national registry containing disease and patient-related characteristics enrolled patients with MDS between January 1, 2006 and December 31, 2019. The Ontario subset of the registry was linked to population-based health system administrative databases. The primary outcome was the impact of statin/oral hypoglycemic medication exposure on overall survival (OS). Cumulative medication exposure (in months) was evaluated from 1-year prior to registry enrollment to date of death or end of follow-up (March 31, 2020) as a time-varying covariate. Cox regression analysis controlling for comorbid disease burden (Aggregated Diagnosis Groups; ADG) and sociodemographic factors (age, sex, rurality, income quintile) examined the relationship between medication exposure and OS. Our secondary outcome was leukemia-free survival (LFS), in which cause-specific hazard model was used to evaluate the association between medication exposure and LFS, taking death as the competing event. Results: In total, 533 patients aged >66 years were included (395 lower-risk IPSS, 130 higher-risk IPSS). The median age was 76.0 years (IQR 72.0-81.0), 65.1% were male and 9% had secondary MDS. The mean follow-up was 2.6 years (SD+ 2.4). Starting one year prior to registry enrollment and until the end of follow-up, 49.3% used a statin, 18.9% used metformin, 9.0% used a sulfonylurea and 6.4% used a DPP4i. On univariate analysis, we identified an improved OS in the lower-risk IPSS group using DPP4i (HR 0.98, 95% CI 0.95-1.00, p=0.05), while there was no significant difference in the higher-risk IPSS group for users of DPP4i (HR 1.03, 95% CI 0.99-1.07, p=0.21). In both lower and higher-risk IPSS groups, there was no difference in mortality for statins (HR 1.00, CI 1.00-1.01, p=0.93), metformin (HR 1.00, CI 0.99-1.01, p=0.81) and sulfonylureas (HR 1.00, CI 0.99-1.02, p=0.43). Increased age (p There was no association between exposure to the studied medications and LFS in the lower-risk group: metformin (HR 0.99, 95% CI 0.96-1.02, p=0.32), sulfonylureas (HR 0.99, 95% CI 0.94-1.04, p=0.57) and statins (HR 0.99, 95% CI 0.98-1.01, p=0.41). The impact of DPP4i exposure on LFS could not be assessed in lower risk disease due to infrequent events. There was also no association in the higher-risk IPSS group: DPP4i (HR 1.06, 95% CI 1.00-1.12, p=0.05), metformin (HR 1.02, CI 0.98-1.05, p=0.34), sulfonylureas (HR 1.04, 1.00-1.08, p=0.07) and statins (HR 1.02, 1.00-1.04, p=0.12). On multivariable analysis in the lower-risk IPSS group, no associations were identified between the use of medications of interest and all-cause mortality: DPP4i (HR 0.98, 95% CI 0.95-1.00, p=0.06), metformin (HR 1.00, 95% CI 0.99-1.01, p=0.99), sulfonylurea (HR 1.00, 95% CI 0.99-1.02, p=0.65) and statins (HR 1.00, 95% CI 0.99-1.00, p=0.56). In those with known cause of death, the main cause of death amongst DPP4i users was infection (35.7%) followed by acute myeloid leukemia (AML) (21.4%) and cardiac disease (14.3%), while the main cause of death in patients not on DPP4i was progressive MDS (23.2%) followed by AML (22.5%) and infections (22.1%). Conclusions: DPP4i may confer a survival benefit in lower-risk but not higher-risk MDS that cannot be explained by a reduction in cardiovascular deaths. Metformin, sulfonylureas and statins showed no impact on OS and LFS in lower and higher-risk groups. Improved bone marrow function through exosome inhibition and increased granulocyte-macrophage colony stimulating activity is the suggested mechanism for the potential survival benefit with DPP4i in lower-risk IPSS patients. This represents the first study evaluating the impact of oral hypoglycemic mediations and statins in a large cohort of patients with MDS. Further prospective studies are required to further evaluate the effects of DPP4i in MDS. Disclosures Leber: AMGEN: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; TaiHo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Otsuka: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Khalaf: Pfizer: Honoraria; Novartis: Honoraria; Paladin: Honoraria. Sabloff: TaiHo: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Jaxx: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; ROCHE: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. Yee: Astex: Membership on an entity's Board of Directors or advisory committees, Research Funding; Geron: Research Funding; Janssen: Research Funding; Jazz: Research Funding; MedImmune: Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Onconova: Research Funding; Tolero: Research Funding; AbbVie: Honoraria; Bristol-Myers Squibb/Celgene: Membership on an entity's Board of Directors or advisory committees; Otsuka: Membership on an entity's Board of Directors or advisory committees; Paladin: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Shattuck Labs: Membership on an entity's Board of Directors or advisory committees; TaiHo: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; F. Hoffmann La Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; Forma Therapeutics: Research Funding. Buckstein: Celgene: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding; TAIHO: Research Funding; Otsuka: Research Funding.

The optimal hemoglobin (HgB) threshold for red blood cell transfusions in adult patients with myelodysplastic syndromes (MDS) has not been defined. We conducted a randomized multi-center study of two transfusion algorithms (liberal, to maintain Hgb 110-120 g/L, versus restrictive, 85-105 g/L) and combined our findings from RBC-ENHANCE with those of REDDS a previously published study of similar design. Primary objectives were measures of compliance to transfusion thresholds and the achievement of a 15 g/L difference in pre-transfusion Hgb. Secondary outcomes included measures of QOL, iron studies and safety. 66 patients were randomized between February 2015-2020, 33 to each arm in 15 international participating sites. The compliance was 58% and 81% in the restrictive and liberal arms respectively and the mean pre-transfusion Hgb thresholds for restrictive and liberal arms were 85.9 (SD 9) and 98.8 g/L (SD 9). Patients in the liberal arms experienced a mean of 3.4 (SD 2.6) more transfusion visits and received a mean of 5.3 (SD 5.5) extra units of blood during the 12-week study. Selected QOL scores were superior pre-transfusion and more patients achieved clinically important differences in the liberal arm. Further data are needed to establish the feasibility of liberal transfusion policies in MDS outpatients. Trial Registration: REDDS: ISRCTN26088319 RBC-ENHANCE: NCT 02099669

Acute myeloid leukemia (AML) is a hematological malignancy that predominantly affects the elderly. Prognosis declines with age. For those who cannot tolerate intensive chemotherapy, historically established treatment options have been hypomethylating agents (HMAs), low dose cytarabine (LDAC), and best supportive care (BSC). As the standard of care evolves for those unfit for intensive chemotherapy, there is a need to understand established treatment pathways, clinical outcomes and healthcare resource utilization in Canada. The CURRENT study was a retrospective chart review of AML patients not eligible for intensive chemotherapy who initiated first-line treatment between 1 January 2015 and 31 December 2018. Data were collected from 170 Canadian patients treated at six hematology centers, of whom 118 received systemic therapy and 52 received BSC as first-line treatment. Median overall survival was 8.58 months and varied from 2.96 months for BSC to 13.31 months for HMAs. Over 80% of patients had at least one outpatient visit, and 67% of patients receiving systemic therapy and 71% of those receiving BSC had at least one admission to hospital, during their first line of therapy. A total of 96 (81.4%) patients receiving first line systemic therapy and 39 (75.0%) of those receiving first line BSC had at least one red blood cell or platelet transfusion. These findings highlight the unmet need for novel therapies for patients ineligible for intensive chemotherapy.

Although total duration of tyrosine kinase inhibitor (TKI) therapy and of molecular response at 4 log reduction or deeper (MR4) correlates with treatment-free remission (TFR) success after TKI discontinuation, the optimal cut-off values of the duration remain unresolved. Thus, 131 patients were enrolled into the Canadian TKI discontinuation study. The molecular relapse-free survival (mRFS) was defined from imatinib discontinuation till molecular recurrence, that is, major molecular response (MMR) loss and/or MR4 loss. We evaluated mRFS at 12 months after imatinib discontinuation, analyzed it according to the imatinib treatment duration and MR4 duration, and calculated P value, positive (PPV) and negative predictive value (NPV) in the yearly cut-off period of time. The shortest cut-off was sought that met the joint criteria of a P value ≤ 0·05, PPV ≥ 60% and NPV ≥ 60%. We propose six years as the shortest imatinib duration cut-off with a P value 0·01, PPV 68% and NPV 62%: The patients treated with imatinib duration ≥ 6 years showed a superior mRFS rate (61·8%) compared to those with less treatment (36·0%). Also, 4·5 years MR4 duration as the shortest cut-off with a P value 0·003, PPV 63% and NPV 61%: those with MR4 duration ≥ 4·5 years showed a higher mRFS rate (64·2%) than those with a shorter MR4 duration (41·9%).

Cytoplasmic and membrane-bound BCL-2 family proteins regulate apoptosis, a form of programmed cell death, via dozens of binary protein interactions confounding measurement of the effects of inhibitors in live cells. In cancer, apoptosis is frequently dysregulated, and cell survival depends on antiapoptotic proteins binding to and inhibiting proapoptotic BH3 proteins. The clinical success of BH3 mimetic inhibitors of antiapoptotic proteins has spawned major efforts by the pharmaceutical industry to develop molecules with different specificities and higher affinities. Here, quantitative fast fluorescence lifetime imaging microscopy enabled comparison of BH3 mimetic drugs in trials and preclinical development by measuring drug effects on binding affinities of interacting protein pairs in live cells. Both selectivity and efficacy were assessed for 15 inhibitors of four antiapoptotic proteins for each of six BH3 protein ligands. While many drugs target the designed interaction, most also have unexpected selectivity and poor efficacy in cells.

This analysis from the phase II BRIGHT AML 1003 trial reports the long-term efficacy and safety of glasdegib + low-dose cytarabine (LDAC) in patients with acute myeloid leukemia ineligible for intensive chemotherapy. The multicenter, open-label study randomized (2:1) patients to receive glasdegib + LDAC (de novo, n = 38; secondary acute myeloid leukemia, n = 40) or LDAC alone (de novo, n = 18; secondary acute myeloid leukemia, n = 20). At the time of analysis, 90% of patients had died, with the longest follow-up since randomization 36 months. The combination of glasdegib and LDAC conferred superior overall survival (OS) versus LDAC alone; hazard ratio (HR) 0.495; (95% confidence interval [CI] 0.325–0.752); p = 0.0004; median OS was 8.3 versus 4.3 months. Improvement in OS was consistent across cytogenetic risk groups. In a post-hoc subgroup analysis, a survival trend with glasdegib + LDAC was observed in patients with de novo acute myeloid leukemia (HR 0.720; 95% CI 0.395–1.312; p = 0.14; median OS 6.6 vs 4.3 months) and secondary acute myeloid leukemia (HR 0.287; 95% CI 0.151–0.548; p < 0.0001; median OS 9.1 vs 4.1 months). The incidence of adverse events in the glasdegib + LDAC arm decreased after 90 days’ therapy: 83.7% versus 98.7% during the first 90 days. Glasdegib + LDAC versus LDAC alone continued to demonstrate superior OS in patients with acute myeloid leukemia; the clinical benefit with glasdegib + LDAC was particularly prominent in patients with secondary acute myeloid leukemia. ClinicalTrials.gov identifier: NCT01546038., Open Access funding enabled and organized by Projekt DEAL. This study was funded by Pfizer.

Iron overload (IO) reflected by elevated ferritin is associated with increased mortality in myelodysplastic syndromes (MDS), however, ferritin is an imperfect metric. Elevated labile plasma iron correlates with clinical outcomes and transferrin saturation (TSAT)80%, but is not readily measurable. The trajectory of TSAT, and its association with clinical outcomes remain undefined. Canadian MDS registry patients were evaluated. Mean TSAT, mean ferritin and transfusion dose density (TDD) were determined. Survival was evaluated by TSAT and ferritin (80%), (≤500µg/L, 501-800µg/L,800µg/L). In 718 patients, median age was 74 years. 12%, 31%, 29%, 15% and 13% were IPSS-R very low, low, intermediate, high and very high. TSAT and ferritin were moderately correlated (r=0.63, p80% trended with inferior cardiac death free survival (CDFS) (p=0.053). In univariate analysis, age, IPSS-R, blast percentage, performance status by ECOG, frailty, Charlson Comorbidity Index, iron chelation (Y/N), TDD, TSAT and ferritin were significantly associated with inferior OS. By multivariable analysis, TSAT80% (p=0.007) remained significant for OS (R2 30.3%). In MDS, TSAT80% and ferritin800µg/L portended inferior OS, PFS and LFS. TSAT may indicate the presence of oxidative stress, and is readily measurable in a clinical setting. The relationship between TSAT and cardiac DFS warrants further study.

Ruxolitinib improves splenomegaly and other disease-related symptoms in patients with myelofibrosis, but over time, many patients lose this benefit. It is difficult to determine whether this is due to resistance or intolerance to the drug; thus, we have used the more inclusive term of ruxolitinib failure. The survival of patients with myelofibrosis after ruxolitinib failure is poor but varies significantly by the pattern of the failure, underlining the need for a clinically appropriate classification. In this review, we propose diagnostic guidance for early recognition of the pattern of ruxolitinib failure and we recommend treatment options. The most frequent patterns of ruxolitinib failure are loss or failure to obtain a significant reduction in splenomegaly or symptom response, and the development or persistence of clinically significant cytopenias. Ruxolitinib dose modification and other ancillary therapies are sometimes helpful, and splenectomy is a palliative option in selected cases. Stem-cell transplantation is the only curative option for these patterns of failure, but its restricted applicability due to toxicity highlights the importance of ongoing clinical trials in this area. Recent approval of fedratinib by the US Food and Drug Administration provides an alternative option for patients with suboptimal or loss of spleen response. The transformation of myelofibrosis to accelerated or blast phase is an infrequent form of failure with an extremely poor prognosis, whereby patients who are ineligible for transplantation have limited treatment options.

The doubling time (DT) of the BCR-ABL1 quantitative polymerase chain reaction (qPCR) transcript level reflects the re-growing fraction of leukaemic cells after discontinuation of tyrosine kinase inhibitor (TKI). The present study analyzed monthly DT within six months after imatinib discontinuation in 131 patients. Monthly DT was calculated as x = ln(2)/K, where x is the DT and K is the fold BCR-ABL1 change from the previous value divided by the number of days between each measurement. The optimal DT value was determined as 12·75 days at two months using a recursive partitioning method. The patients were stratified into three groups: the high-risk group (DT12·75 days but0, with rapidly proliferating chronic myeloid leukaemia (CML) cells; n = 26) showed the lowest molecular relapse-free survival (mRFS) of 7·7% at 12 months, compared to 53·6% in the intermediate-risk group (DT≥12·75 days, with slowly proliferating CML cells; n = 16) or 90·0% in the low-risk group (DT≤0, i.e., without proliferating CML cells; n = 71; P 0·001). Monthly assessment of DT helps identify high-risk patients for treatment-free remission failure with an imminent risk of molecular recurrence, and to define low-risk patients who can be spared the frequent monitoring of monthly molecular tests.

Background: The incorporation of patient-reported outcomes with traditional disease risk classification, was found to strengthen survival prediction in patients with myelodysplastic syndromes (MDS). A recently reported model, FA-IPSS(h), found that patients' reported fatigue, assessed by the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life-Core 30 (QLQ-C30), among higher-risk IPSS population, further stratifies them into distinct sub-groups with different survival outcomes (Efficace et al, 2018). Compared to the IPSS, the revised IPSS (IPSS-R) is more refined in prognostic assessment and an IPSS-R score of > 3.5 may identify higher risk disease (Pfeilstocker et al, 2016). The Edmonton Symptom Self Assessment Scale (ESAS) Global Fatigue Scale (GFS), is a single-item fatigue rating scale (0-10, with 10 being the highest degree), which has been previously recommended by the National Comprehensive Cancer Network to screen for fatigue in all cancer populations. Aims: (1) to validate the FA-IPSS(h), among the Canadian MDS registry (2) investigate whether a modified index, integrating higher risk by IPSS-R with patient reported fatigue according to the GFS, is able to identify individual subgroups with divergent overall survival (OS). Methods: All adult patients diagnosed with MDS with an IPSS-R score >3.5 within 6 months before the date of registration were eligible for this analysis. Fatigue was assessed both by the QLQ-C30 questionnaire and the GFS. Frailty was assessed by the Canadian Study of Health and Aging (CSHA) 9 point Rockwood clinical frailty scale. Survival was calculated using standard Kaplan-Meier analysis. Results: This analysis included 331 patients. Median age was 73 years (range, 30-98 years), 65.7% were male, median blast % was 6% (range, 0-30), median IPSS-R score was 5.2 (range, 3.5-10) and 55% had high and intermediate-2 (Int-2) IPSS risk, 68% had high and very high IPSS-R risk disease, 66% were exposed to a hypomethylating agent. Median fatigue scores increased with Rockwood frailty scores. The median QLQ-C30 fatigue score was 33 (interquartile range (IQR), 22-55.6) and 4 (IQR, 2-6) by the GFS with 59% recording high fatigue (>4). At a median follow-up of 17 months (IQR, 9-30 months), 233 deaths were observed. The actuarial median OS was 19.3 months (95% CI, 16.5-21.7). We applied the FA-IPSS(h) using QLQ-C30 fatigue cutoffs of 45 (figure 1a) and found a significant difference in OS (p3.5 + Low Fatigue (3.5 + High Fatigue (≥45) (n=96). We found a significant difference in OS between these 2 groups, median OS 19.5 months (95% CI, 17.2-24.3) in group A versus 15.2 months (95% CI, 11.9-22.0) in group B (p=0.02) (figure 1b). We found similar results with these refinements, using the QLQ-C30 cutoff of 33 (the median in our patient population) (p4), was able to distinguish OS using the IPSS (p3.5 (p=0.005) (figure 1d). Conclusions: We were able to externally validate the FA-IPSS (h) using a threshold QLQ-C30 fatigue score of 45, as originally described and 33 (Canadian median), using both the IPSS and IPSS-R (score >3.5) classifications to define higher risk MDS. The easier to deploy ESAS GFS score of >4 further discriminates survival using the IPSS and IPSS-R. This emphasizes the power of self-reported fatigue at refining OS predictions in higher risk MDS and further bolsters the importance of considering patient related outcomes in global assessments. Disclosures Geddes: Taiho: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding. Keating:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Hoffman La Roche: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Merck: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy; Servier: Membership on an entity's Board of Directors or advisory committees; Shire: Membership on an entity's Board of Directors or advisory committees; Taiho: Membership on an entity's Board of Directors or advisory committees. Leber:Lundbeck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Otsuka Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda/Palladin: Honoraria, Membership on an entity's Board of Directors or advisory committees; Treadwell: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Leitch:AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Taiho: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Exjade: Speakers Bureau. Shamy:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Storring:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Nevill:Jazz Pharmaceuticals: Honoraria; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Delage:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Elemary:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Chodirker:Hoffman Laroche: Honoraria. Buckstein:Novartis: Honoraria; Celgene: Research Funding; Takeda: Research Funding; Celgene: Honoraria; Astex: Honoraria.

Ruxolitinib was recently approved for the treatment of patients with polycythemia vera who are resistant/intolerant to hydroxyurea based on data from the RESPONSE studies. This phase 3b, Expanded Treatment Protocol study (NCT02292446) of ruxolitinib for hydroxyurea-resistant/intolerant patients with polycythemia vera (

Summary: Unleashing blocked apoptosis has emerged as an important tool in treating cancer as shown by the recent success of the BCL2 inhibitor venetoclax. However, MCL1 represents another important target as it is the predominant survival signal in many types of cancers and functions as a resistance mechanism to BCL2 inhibition. Caenepeel and colleagues and Ramsey and colleagues have developed two novel, potent, and selective MCL1 inhibitors that are effective against many hematologic malignancies, and Nangia and colleagues describe how one of these inhibitors can be successfully combined with BCL-xL and MEK inhibition to treat KRAS-mutated lung cancer. See related article by Ramsey et al., p. 1566. See related article by Caenepeel et al., p. 1582. See related article by Nangia et al., p. 1598.

In 2008 the first evidence-based Canadian consensus guideline addressing the diagnosis, monitoring and management of transfusional iron overload in patients with myelodysplastic syndromes (MDS) was published. The Canadian Consortium on MDS, comprised of hematologists from across Canada with a clinical and academic interest in MDS, reconvened to update these guidelines. A literature search was updated in 2017; topics reviewed include mechanisms of iron overload induced cellular damage, evidence for clinical endpoints impacted by iron overload including organ dysfunction, infections, marrow failure, overall survival, acute myeloid leukemia progression, and endpoints around hematopoietic stem-cell transplant. Evidence for an impact of iron reduction on the same endpoints is discussed, guidelines are updated, and areas identified where evidence is suboptimal. The guidelines address common questions around the diagnosis, workup and management of iron overload in clinical practice, and take the approach of who, when, why and how to treat iron overload in MDS. Practical recommendations for treatment and monitoring are made. Evidence levels and grading of recommendations are provided for all clinical endpoints examined.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematologic disease characterized by intravascular hemolysis, thrombophilia, and marrow failure. Its phenotype is due to absent or reduced expression of GPI-linked complement regulators and subsequent sensitivity of hematopoietic cells to complement-mediated damage and lysis. Introduction of the terminal complement inhibitor eculizumab drastically improved outcomes in PNH patients; however, despite this improvement, there remain several challenges faced by PNH patients and physicians who care for them. One of the most important is increasing awareness of the heterogeneity with which patients can present, which can lead to significant delays in recognition. Data from the Canadian PNH Registry are presented to demonstrate the variety of presenting symptoms. In Canada, geography precludes consolidation of care to just a few centers, so management is distributed across academic hospitals, linked together as the Canadian PNH Network. The Network over the last several years has developed educational programs and clinical checklists and has worked to standardize access to diagnostics across the country. Herein, we address some of the common diagnostic and therapeutic challenges faced by PNH physicians and give our recommendations. Gaps in knowledge are also addressed, and where appropriate, consensus opinion is provided.

The incorporation of patient-reported outcomes with traditional disease risk classification was found to strengthen survival prediction in patients with myelodysplastic syndromes (MDS). In the present Canadian MDS registry analysis, we validate a recently reported prognostic model, the Fatigue-International Prognostic Scoring System among higher-risk patients [FA-IPSS(h)], which incorporates patients' reported fatigue, assessed by the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life-Core 30 (QLQ-C30), with a threshold of ≥45 points, in higher IPSS score, stratifying them into distinct subgroups with different survival outcomes. We further validated this concept, using the Revised IPSS >3·5 as cut-off for the definition of higher-risk MDS, and patients' reported fatigue according to Edmonton Symptom Self-Assessment Scale (ESAS) Global Fatigue Scale (GFS), a single-item fatigue rating scale, which is easier to deploy. This emphasises the power of self-reported fatigue at refining overall survival predictions in higher-risk MDS and further bolsters the importance of considering patient-related outcomes in global assessments.

Pathology synopses consist of semi-structured or unstructured text summarizing visual information by observing human tissue. Experts write and interpret these synopses with high domain-specific knowledge to extract tissue semantics and formulate a diagnosis in the context of ancillary testing and clinical information. The limited number of specialists available to interpret pathology synopses restricts the utility of the inherent information. Deep learning offers a tool for information extraction and automatic feature generation from complex datasets. Using an active learning approach, we developed a set of semantic labels for bone marrow aspirate pathology synopses. We then trained a transformer-based deep-learning model to map these synopses to one or more semantic labels, and extracted learned embeddings (i.e., meaningful attributes) from the model’s hidden layer. Here we demonstrate that with a small amount of training data, a transformer-based natural language model can extract embeddings from pathology synopses that capture diagnostically relevant information. On average, these embeddings can be used to generate semantic labels mapping patients to probable diagnostic groups with a micro-average F1 score of 0.779 Â ± 0.025. We provide a generalizable deep learning model and approach to unlock the semantic information inherent in pathology synopses toward improved diagnostics, biodiscovery and AI-assisted computational pathology. Pathology synopses are short texts describing microscopic features of human tissue. Medical experts use their knowledge to understand these synopses and formulate a diagnosis in the context of other clinical information. However, this takes time and there are a limited number of specialists available to interpret pathology synopses. A type of artificial intelligence (AI) called deep learning provides a possible means of extracting information from unstructured or semi-structured data such as pathology synopses. Here we use deep learning to extract diagnostically relevant textual information from pathology synopses. We show our approach can then map this textual information to one or more diagnostic keywords. We provide a generally applicable and scalable method to unlock the knowledge in pathology synopses as a step toward exploiting computer-aided pathology in the clinic. Mu et al. utilize a deep learning natural language processing model as part of an active learning approach to extract diagnostically relevant semantic information from bone marrow pathology synopses. Their findings demonstrate the potential for artificial intelligence in assisting clinicians in assessing, cataloging and triaging medical text datasets such as pathology synopses.

Measurable (minimal) residual disease (MRD) is an established, key prognostic factor in adult B-cell acute lymphoblastic leukemia (B-ALL), and testing for MRD is known to be an important tool to help guide treatment decisions. The clinical value of MRD testing depends on the accuracy and reliability of results. Currently, there are no Canadian provincial or national guidelines for MRD testing in adult B-ALL, and consistent with the absence of such guidelines, there is no uniform Ontario MRD testing consensus. Moreover, there is great variability in Ontario in MRD testing with respect to where, when, and by which technique, MRD testing is performed, as well as in how the results are interpreted. To address these deficiencies, an expert multidisciplinary working group was convened to define consensus recommendations for improving the provision of such testing. The expert panel recommends that MRD testing should be implemented in a centralized manner to ensure expertise and accuracy in testing for this low volume indication, thereby to provide accurate, reliable results to clinicians and patients. All adult patients with B-ALL should receive MRD testing after induction chemotherapy. Philadelphia chromosome (Ph)-positive patients should have ongoing monitoring of MRD during treatment and thereafter, while samples from Ph-negative B-ALL patients should be tested at least once later during treatment, ideally at 12 to 16 weeks after treatment initiation. In Ph-negative adult B-ALL patients, standardized, ideally centralized, protocols must be used for MRD testing, including both flow cytometry and immunoglobulin (Ig) heavy chain and T-cell receptor (TCR) gene rearrangement analysis. For Ph-positive B-ALL patients, MRD testing using a standardized protocol for reverse transcription real-time quantitative PCR (RT-qPCR) for the BCR-ABL1 gene fusion transcript is recommended, with Ig/TCR gene rearrangement analysis done in parallel likely providing additional clinical information.

Background The phase 2 BRIGHT AML 1003 trial evaluated efficacy and safety of glasdegib + low-dose cytarabine (LDAC) in patients with acute myeloid leukemia ineligible for intensive chemotherapy. The multicenter, open-label study randomized patients to receive glasdegib + LDAC (n = 78) or LDAC alone (n = 38). The rate of complete remission (CR) was 19.2% in the glasdegib + LDAC arm versus 2.6% in the LDAC arm (P = 0.015). Methods This post hoc analysis determines whether the clinical benefits of glasdegib are restricted to patients who achieve CR, or if they extend to those who do not achieve CR. Results In patients who did not achieve CR, the addition of glasdegib to LDAC improved overall survival (OS) versus LDAC alone (hazard ratio = 0.63 [95% confidence interval, 0.41–0.98]; P = 0.0182; median OS, 5.0 vs 4.1 months). Additionally, more patients receiving glasdegib + LDAC achieved durable recovery of absolute neutrophil count (≥ 1000/μl, 45.6% vs 35.5%), hemoglobin (≥ 9 g/dl, 54.4% vs 38.7%), and platelets (≥ 100,000/μl, 29.8% vs 9.7%). Transfusion independence was achieved by 15.0% and 2.9% of patients receiving glasdegib + LDAC and LDAC alone, respectively. Conclusions Collectively, these data suggest that there are clinical benefits with glasdegib in the absence of CR. Trial registration ClinicalTrials.gov NCT01546038 (March 7, 2012)

Identifying precise targets of individual cancers remains challenging. Chronic lymphocytic leukemia (CLL) represents the most common adult hematologic malignancy, and trisomy 12 (tri12) represents a quarter of CLL patients. We report that tri12 human pluripotent stem cells (hPSCs) allow for the identification of gene networks and targets specific to tri12, which are controlled by comparative normal PSCs. Identified targets are upregulated in tri12 leukemic cells from a cohort of 159 patients with monoclonal B cell lymphocytosis and CLL. tri12 signaling patterns significantly influence progression-free survival. Actionable targets are identified using high-content drug testing and functionally validated in an additional 44 CLL patient samples. Using xenograft models, interleukin-1 receptor-associated kinase 4 (IRAK4) inhibitor is potent and selective against human tri12 CLL versus healthy patient-derived xenografts. Our study uses hPSCs to uncover targets from genetic aberrations and apply them to cancer. These findings provide immediate translational potential as biomarkers and targets for therapeutic intervention.

We completed a phase 1 dose-escalation trial to evaluate the safety of a dopamine receptor D2 (DRD2) antagonist thioridazine (TDZ), in combination with cytarabine. Thirteen patients 55 years and older with relapsed or refractory acute myeloid leukemia (AML) were enrolled. Oral TDZ was administered at 3 dose levels: 25 mg (n = 6), 50 mg (n = 4), or 100 mg (n = 3) every 6 hours for 21 days. Intermediate-dose cytarabine was administered on days 6 to 10. Dose-limiting toxicities (DLTs) included grade 3 QTc interval prolongation in 1 patient at 25 mg TDZ and neurological events in 2 patients at 100 mg TDZ (gait disturbance, depressed consciousness, and dizziness). At the 50-mg TDZ dose, the sum of circulating DRD2 antagonist levels approached a concentration of 10 μM, a level noted to be selectively active against human AML in vitro. Eleven of 13 patients completed a 5-day lead-in with TDZ, of which 6 received TDZ with hydroxyurea and 5 received TDZ alone. During this period, 8 patients demonstrated a 19% to 55% reduction in blast levels, whereas 3 patients displayed progressive disease. The extent of blast reduction during this 5-day interval was associated with the expression of the putative TDZ target receptor DRD2 on leukemic cells. These preliminary results suggest that DRD2 represents a potential therapeutic target for AML disease. Future studies are required to corroborate these observations, including the use of modified DRD2 antagonists with improved tolerability in AML patients. This trial was registered at www.clinicaltrials.gov as #NCT02096289.

Background: AML is a complex disease that encompasses a huge variation of cytogenetic and mutational backgrounds, which is often complicated by age related functional deficits (Klepin et al. 2013). Given the expanding availability of reduced-intensity treatment options, patient fitness and frailty measures have become increasingly instrumental in the decision between a wide range of treatment options. Furthermore, studies have also demonstrated potential benefits in older patients who receive intensive induction chemotherapy (Julisson 2011), creating a need for additional assessments to identify suitable induction candidates. Some frailty-associated assessments including timed-up-and-go test (TUGT) and the short physical performance battery have been linked to outcomes but are not yet in broad clinical use (Kleplin et al. 2013, Khalaf et al. 2020). To minimize the burden of implementing new patient assessments, we evaluated the utility of commonly available clinical measures of frailty-associated factors including sit-to-stand test and iADL status in predicting patient outcomes. Methods: We performed a retrospective cohort study of elderly patients newly diagnosed with AML at Juravinski Cancer Center between Jan 2019 and Dec 2020. We examined a total of 44 patients aged 65+. The primary outcome was overall survival (OS). Significant risk factors were identified using the Cox proportional hazards model. Results: 43 patients had sufficient data and were included in the analysis. The median age was 70 years (range 65-89), 53% were female and 47% were male. At the time of review, 21 patients were deceased (48.8%). The median survival time was 345 days. 26 patients received full induction treatment (7+3, FLAG-IDA, or Vyxeos), and 18 received conservative treatment (LDAC, azacytidine, or supportive care). The clinical wellness of the patients at diagnosis time was assessed by baseline clinical and laboratory findings. (Table 1) The Cox regression model was used to examine these variables in predicting overall survival (Figure 1). As expected, the ELN risk group was significantly correlated with OS (HR 2.94 95%CI [1.41-6.11]), along with laboratory measures of disease burden including blood blast count (HR 1.02 [1.00-1.03]), WBC, (HR 1.02 [1.01-1.03]) and ANC (HR 1.05 [1.02-1.08]). We then assessed the influence of patient fitness factors on OS. The HCT-CI score was used as an aggregate comorbidities measure. While typically used for post-SCT prognosis, we found that HCT-CI assessed at diagnosis time was a significant predictor of OS (HR 1.22[1.04-1.45]). When added to a multivariate Cox model including ELN and age, the HCT-CI independently predicted OS (p = 0.003) and improved prediction efficiency by the Akaike information criteria (115 vs 122). This corroborates earlier findings by Sorror et al. 2017, who showed incorporation of biochemical and AML-specific variables to HCT-CI yields improved prognostic value. Within the HCT-CI, the AST and cardiac disease scores were the most associated with OS (HR 1.03[1.00-1.05] and 2.27[1.09-4.76]). While clinical and laboratory assessments were readily available, functional assessments of frailty were scarce. Previously reported frailty measures such as KPS score or TUGT were not assessed at the study center. OT/PT routinely administer sit-to-stand or standing balance tests as a part of fall risk assessment. However, this data was only available for 18 patients (41.8%). Independent sit-to-stand was not detected as a significant OS predictor (HR 0.63[0.14-2.83]), possibly related to the very limited sample size. BMI was marginally predictive (HR 1.07[0.99 - 1.08]), but unlike HCT-CI it was not an independent predictor when combined with ELN. Patient age did not significantly predict OS. Conclusion: This single center retrospective study was aimed at examining the role of existing clinical or functional measures of fitness and frailty in predicting overall survival. HCT-CI and ELN were found to be the most predictive factors amongst the variables examined, suggesting that a morbidity index such as HCT-CI could provide prognostic utility. However, functional assessments of frailty were not readily completed, limiting the ability to evaluate their usefulness. A future larger prospective study focused on optimizing and incorporating routine functional assessments of frailty is needed to address this topic. Figure 1 Figure 1. Disclosures Leber: Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Otsuka: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; TaiHo: Honoraria, Membership on an entity's Board of Directors or advisory committees; AMGEN: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Khalaf: Novartis: Honoraria; Paladin: Honoraria; Pfizer: Honoraria.

Background/Introduction: Lower-risk (IPSS low risk and Int-1) myelodysplastic syndromes (MDS) are typically treated supportively to address cytopenias. DNA methyltransferase inhibitors (DNMTi) such as azacitidine and decitabine (DEC) are FDA-approved for higher risk MDS patients (pts), and while the DEC USPI includes IPSS Int-1 pts, it is not widely used in this population. Approved intravenous (IV) or subcutaneous (SC) regimens require 5-7 days of treatment every month burdening older cancer pts due to daily travel and treatment time and may increase potential risk from pandemic SARS-CoV-2 infection. Because DNMTis are rapidly degraded by cytidine deaminase (CDA) in the gut and liver, oral availability has only been recently possible. A randomized study with CC-486, an oral formulation of azacitidine, in the Int-1 population showed a median overall survival (mOS) of approximately 17 months for both placebo and treated patients (Garcia-Manero, 2021). Oral DEC 35 mg/cedazuridine 100 mg (ASTX727) or DEC-C, is an oral fixed dose combination (FDC) of DEC and the CDA inhibitor cedazuridine (CED) resulting in equivalent exposure (99%; 90% CI 93% to 106%) to standard IV DEC 20 mg/m 2 for 5 days in an intra-patient randomized cross-over study (Garcia-Manero et al, ASH 2019). Here, we present data on patients with lower risk MDS from that study. Methods: We used a randomized cross over design with pts randomized 1:1 in the first 2 cycles to either Sequence A: (DEC 35 mg/ CED 100 mg in Cycle 1 and IV DEC at 20 mg/m 2 in Cycle 2), or Sequence B (IV DEC in Cycle 1 and oral DEC/CED in Cycle 2). Cycles were repeated every 28 days unless delays were needed, and all patients received oral DEC-C in Cycles 3+ until disease progression or unacceptable toxicity. We conducted an intra-patient comparison of DEC PK (DEC AUC equivalence over 5 days of dosing). Pts were eligible as per the FDA-approved label of IV DEC (MDS pts by FAB classification including CMML, or MDS IPSS Intermediate-1, 2 or high-risk pts). Clinical endpoints were best response as assessed by an independent expert panel according to IWG 2006 response criteria, transfusion independence (TI), overall survival (OS), and safety. Results: Of the 133 pts treated in ASCERTAIN, 69 had a diagnosis of lower-risk MDS (93% Int-1, 7% LR). Median age was 70.0 years (range 45-87), 65% were male, median weight was 84 kg (range 50-127), median baseline hematologic parameters were: hemoglobin 89 g/L (range 69.8-146.5), WBCs 1.50 X 10 9/L (range 0.11-7.1), platelets (plt) 86 x 10 9/L (range 5-703), bone marrow blasts 4% (range 0-18), cytogenetics: 7 (10.1%) poor-risk, 21 (30.4%) intermediate risk, 37 (53.6%) better-risk, 4 (5.7%) missing or not evaluable. 27(39%) of the pts were RBC transfusion dependent (TD) and 6 (9%) plt TD. 17 (25%) had received prior MDS treatment, 3% prior DNMTi. Pts received a median of 9 cycles of therapy (range 1-28). Treatment-emergent adverse events of CTCAE Gr 3 or higher in >10% of pts, independent of relationship to ASTX727, included cytopenias (neutropenia [59%], thrombocytopenia [58%], anemia [48%], leukopenia [26%]), febrile neutropenia (32%), and pneumonia (19%). Sixteen pts (23%) achieved Complete Response (CR), 18 (26%) had marrow CR (mCR), including 9 (13%) with hematologic improvement (HI). Overall Response rate (ORR; CR + PR+ mCR + HI) was 57%. Of those RBC or plt TD at baseline, 13 (48%) became RBC TI and 4 (67%) became plt TI. With approximately 32 months of median follow up, neither median leukemia-free survival (mLFS) nor mOS had been reached (Figure 1). Twelve pts (17%) went on to allogeneic stem cell transplant. Conclusions: Oral decitabine/cedazuridine given as a FDC in MDS pts produced equivalent PK exposure to 20 mg/m 2 IV DEC; in lower risk MDS pts with treatment indicated, the agent was generally well-tolerated with prolonged treatment and could result in mLFS and mOS which exceeds 32 months. This FDC and other dosing regimens of oral DEC-C should be further studied in this patient population. References: Garcia-Manero, et al, ASH 2019 Savona, et al, Int. MDS Symp. 2021 Garcia-Manero, et al, Phase III, Randomized, Placebo-Controlled Trial of CC-486 (Oral Azacitidine) in Patients with Lower-Risk Myelodysplastic Syndromes. J.Clin.Onc. 2021 39:13, 1426-1436 Figure 1 Figure 1. Disclosures McCloskey: Pfizer: Consultancy; Jazz: Consultancy, Speakers Bureau; COTA: Other: Equity Ownership; Incyte: Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Novartis: Consultancy; BMS: Honoraria, Speakers Bureau; Amgen: Speakers Bureau. Griffiths: Alexion Pharmaceuticals: Consultancy, Research Funding; Abbvie: Consultancy, Honoraria; Taiho Oncology: Consultancy, Honoraria; Genentech: Research Funding; Novartis: Honoraria; Takeda Oncology: Consultancy, Honoraria; Astex Pharmaceuticals: Honoraria, Research Funding; Celgene/Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Apellis Pharmaceuticals: Research Funding; Boston Biomedical: Consultancy. Yee: Paladin: Membership on an entity's Board of Directors or advisory committees; TaiHo: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Research Funding; Geron: Research Funding; Janssen: Research Funding; Jazz: Research Funding; MedImmune: Research Funding; Onconova: Research Funding; Tolero: Research Funding; AbbVie: Honoraria; Bristol-Myers Squibb/Celgene: Membership on an entity's Board of Directors or advisory committees; Otsuka: Membership on an entity's Board of Directors or advisory committees; Shattuck Labs: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; F. Hoffmann La Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; Forma Therapeutics: Research Funding; Astex: Membership on an entity's Board of Directors or advisory committees, Research Funding. Zeidan: Novartis: Consultancy, Other: Clinical Trial Committees, Travel support, Research Funding; Genentech: Consultancy; Ionis: Consultancy; Astellas: Consultancy; Epizyme: Consultancy; AbbVie: Consultancy, Other: Clinical Trial Committees, Research Funding; Jasper: Consultancy; Cardiff Oncology: Consultancy, Other: Travel support, Research Funding; BeyondSpring: Consultancy; Loxo Oncology: Consultancy, Other: Clinical Trial Committees; Janssen: Consultancy; Acceleron: Consultancy, Research Funding; AstraZeneca: Consultancy; Kura: Consultancy, Other: Clinical Trial Committees; Gilead: Consultancy, Other: Clinical Trial Committees; Agios: Consultancy; Daiichi Sankyo: Consultancy; Boehringer Ingelheim: Consultancy, Research Funding; Geron: Other: Clinical Trial Committees; BMS: Consultancy, Other: Clinical Trial Committees, Research Funding; BioCryst: Other: Clinical Trial Committees; Pfizer: Other: Travel support, Research Funding; Aprea: Consultancy, Research Funding; ADC Therapeutics: Research Funding; Jazz: Consultancy; Incyte: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Astex: Research Funding. Al-Kali: Astex: Other: Research support to institution; Novartis: Research Funding. Patel: Celgene-BMS: Membership on an entity's Board of Directors or advisory committees; PVI: Honoraria; Agios: Membership on an entity's Board of Directors or advisory committees. Sabloff: Pfizer: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; ROCHE: Membership on an entity's Board of Directors or advisory committees; TaiHo: Membership on an entity's Board of Directors or advisory committees; Jaxx: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees. Dao: Astex Pharmaceuticals, Inc.: Current Employment. Fazal: Taiho Pharmaceuticals: Consultancy, Honoraria, Speakers Bureau; Stemline Therapeutics: Consultancy, Honoraria, Speakers Bureau; Sanofi Genzyme: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau; Karyopharm Pharmaceuticals: Consultancy, Honoraria, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Honoraria, Speakers Bureau; Janssen Oncology: Consultancy, Honoraria, Speakers Bureau; Incyte: Consultancy, Honoraria, Speakers Bureau; Glaxo Smith Kline: Consultancy, Honoraria, Speakers Bureau; Gilead Sciences: Consultancy, Honoraria, Speakers Bureau; Bristol Myers Squibb: Consultancy, Honoraria, Speakers Bureau; AMGEN: Consultancy, Honoraria, Speakers Bureau; Agios: Consultancy, Honoraria, Speakers Bureau; Takeda: Consultancy, Honoraria, Speakers Bureau. Odenike: AbbVie, Celgene, Impact Biomedicines, Novartis, Taiho Oncology, Takeda: Consultancy; Celgene, Incyte, AstraZeneca, Astex, NS Pharma, AbbVie, Gilead, Janssen, Oncotherapy, Agios, CTI/Baxalta, Aprea: Research Funding. Kantarjian: AbbVie: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Ascentage: Research Funding; Pfizer: Honoraria, Research Funding; BMS: Research Funding; Daiichi-Sankyo: Research Funding; Amgen: Honoraria, Research Funding; Ipsen Pharmaceuticals: Honoraria; Jazz: Research Funding; Astellas Health: Honoraria; Immunogen: Research Funding; Astra Zeneca: Honoraria; Aptitude Health: Honoraria; KAHR Medical Ltd: Honoraria; NOVA Research: Honoraria; Precision Biosciences: Honoraria; Taiho Pharmaceutical Canada: Honoraria. DeZern: Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Taiho: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees. Roboz: Novartis: Consultancy; Mesoblast: Consultancy; Jasper Therapeutics: Consultancy; Jazz: Consultancy; MEI Pharma - IDMC Chair: Consultancy; Daiichi Sankyo: Consultancy; Otsuka: Consultancy; Bristol Myers Squibb: Consultancy; Blueprint Medicines: Consultancy; Bayer: Consultancy; AstraZeneca: Consultancy; Astellas: Consultancy; Astex: Consultancy; Amgen: Consultancy; Agios: Consultancy; Actinium: Consultancy; AbbVie: Consultancy; Janssen: Research Funding; Celgene: Consultancy; Glaxo SmithKline: Consultancy; Helsinn: Consultancy; Janssen: Consultancy; Pfizer: Consultancy; Roche/Genentech: Consultancy. Busque: Novartis: Consultancy. Leber: Astellas: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Otsuka: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; TaiHo: Honoraria, Membership on an entity's Board of Directors or advisory committees; AMGEN: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Hao: Astex Pharmaceuticals, Inc.: Current Employment. Keer: Astex Pharmaceuticals, Inc.: Current Employment. Azab: Astex Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees. Savona: Geron: Consultancy, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; CTI: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS-Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; NOVARTIS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Ryvu: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sierra Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Taiho: Consultancy, Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; ALX Oncology: Research Funding; Astex: Research Funding; Incyte: Research Funding.

Background: Asciminib (ASC) is a novel, first in class inhibitor specifically targeting the ABL myristate pocket. Phase 3 data comparing ASC to bosutinib have shown a higher rate of major molecular (MMR; 25.5% vs 13.2%) and complete cytogenetic response (40.8% vs 24.2%) at 6 months (mo) in CML patients (pts) in chronic phase (CP) who have failed at least two lines of TKI therapy with a favorable adverse event profile. ASC is available through a compassionate use program for heavily pre-treated CML pts. We share our real-world experience for the use of ASC in CML pts from this program across Canada. Methods: Data were collected on 22 CML pts treated with ASC from 2018 to 2021. Prior TKI history was recorded including: reason for failure to prior therapy, acquired mutations, prior cardiovascular (CV) events and outcome on ASC. BCR-ABL qPCR was performed every 3 mo at each institution. Achievement of MMR and molecular response of 2 log reduction (MR2) was assessed at 6/12 mo, and the most recent assessment. ASC dosing was also assessed at each time-point. Adverse events, resistance, and discontinuation of ASC were captured. Results: Median age was 68 years (range 20-92). 19 were in 1 st CP, 2 in accelerated phase (AP) and 1 in 2 nd CP. The median number of previous TKIs was 3 (range 2-5) with 17 pts (77%) failing at least 3 TKIs; 19 pts (86%) failing imatinib, 17 (77%) dasatinib, 12 (55%) nilotinib, 17 (77%) bosutinib, and 10 (45%) ponatinib. Median duration from first TKI to ASC was 94 mo (range 11-233). 17/22 (77%) pts had a history of a CV event including stroke, peripheral arterial disease, or coronary artery disease. 4 pts had a preexisting T315I mutation. Pts failed previous TKI therapy due to A) resistance or suboptimal response to TKI (n=15, 68%) and B) intolerance to previous TKI (n=7, 32%). With a median of 16 mo follow-up (range 1-34), MMR was noted in 3/17 (18%) and 3/8 (38%) pts evaluated at 6 and 12 mo, respectively. MR2 was noted in 7/17 (41%) and 4/8 pts (50%) at 6/12 mo (Table 1). The cumulative incidence of MMR considering competing events (i.e. ASC discontinuation) was 20.5% (95%CI: 6-41%) and 34.4% (13-57%) while MR2 was 43.8% (22-64%) and 49.4% (25-69%) at 6/12 mo (Fig 1). The proportion of pts in MMR increased from a baseline of 5% to 18%, 18%, 30%, and 38% at 3, 6, 9 and 12 mo. Pts without T315I mutation (n=18) started with a dose of 40mg bid, while pts with T315I started at either 80mg or 120mg bid, then gradually escalated aiming to 200mg bid. 4 pts discontinued the medication due to treatment failure (n=3) or grade 4 thrombocytopenia (n=1). Of those who discontinued, 2 were in AP on initiation of ASC. Side effects included myalgias (n=4), elevated lipase (n=2) and pleural/pericardial effusions (n=2). No CV events were noted in 22 pts. There was no event of disease progression to advanced disease while on ASC therapy or acquisition of new ABL1 kinase domain mutation. The MMR and MR2 rate was lower in ponatinib pre-treated pts (n=10) compared to ponatinib naïve pts (n=12) (Table 1). The MMR and MR2 rates in pts with a T315I mutation (all 4 were ponatinib pre-treated) are at least similar or better than those without T315I. No difference in MMR or MR2 rate was noted between the 2 groups of resistance/suboptimal response vs intolerant to prior TKI therapy. In a subgroup analysis of pts with a past history of a CV event (n=17), no pt discontinued ASC due to another event after a median duration of 17 mo on ASC (range 3-34). Thus, these pts with otherwise very limited options had a reasonable response to ASC without increased risk of CV toxicity (Table 1). Conclusion: In a Canadian real-world experience of ASC use within a compassionate access program in heavily-pretreated CML pts (many with a history of prior CV event), MMR and MR2 rates were comparable to that with ASC in the published literature. No new CV events were noted during ASC therapy in the present group of patients. Figure 1 Figure 1. Disclosures Busque: Novartis: Consultancy. Leber: Jazz: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; TaiHo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Otsuka: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AMGEN: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Kaedbey: Jewish General Hospital - McGill University: Current Employment; Royal Victoria Hospital Lakeshore Hospital: Ended employment in the past 24 months; Celgene/BMS, Janssen: Honoraria; Takeda, Sanofi: Honoraria. Assouline: Johnson&Johnson: Current equity holder in publicly-traded company; Gilead: Speakers Bureau; Amgen: Current equity holder in publicly-traded company, Research Funding; Novartis: Honoraria, Research Funding; Eli Lilly: Research Funding; Roche/Genentech: Research Funding; Jewish General Hospital, Montreal, Quebec: Current Employment; Takeda: Research Funding; BeiGene: Consultancy, Honoraria, Research Funding; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria. Kim: Novartis: Consultancy, Honoraria, Research Funding; Bristol- Meier Squibb: Research Funding; Pfizer: Honoraria.

Introduction: Hypomethylating agents (HMAs) or DNA methyltransferase inhibitors (DNMTi) such as decitabine or azacitidine are established standard of care for the treatment of MDS and CMML. The oral bioavailability of these agents has been limited due to rapid degradation by cytidine deaminase (CDA) in the gut and liver, hence requiring intravenous infusion or subcutaneous injections daily for 5-7 days every month (m). This parenteral administration requirement adds significant burden to older cancer patients due to daily time commitment and travel to treatment centers. It also increases exposure to and infection risk with SARS-CoV-2 during the COVID-19 pandemic. Oral decitabine 35 mg/cedazuridine 100 mg (ASTX727) is an oral fixed dose combination drug of decitabine and the CDA inhibitor cedazuridine that have shown 99% (90% CI 93% to 106%) equivalent exposure to standard dose IV decitabine 20 mg/m2 in a randomized cross-over study (Garcia-Manero et al, ASH 2019). Here, we present the clinical efficacy and safety results of oral decitabine/cedazuridine from 133 patient study in MDS and CMML (ASTX727-02 ASCERTAIN study). Methods: We used a randomized cross over design where patients were randomized in the first 2 cycles 1:1 to either Sequence A: decitabine 35 mg/ cedazuridine 100 mg in Cycle 1 followed by IV decitabine at 20 mg/m2 in Cycle 2, or Sequence B: IV decitabine in Cycle 1 followed by oral decitabine/cedazuridine in Cycle 2 to do an intra-patient comparison of decitabine PK (primary PK endpoint: decitabine AUC equivalence over 5 days of dosing). Cycles were repeated every 28 days. All patients received oral decitabine/cedazuridine in all subsequent cycles from Cycle 3 onwards until disease progression or unacceptable toxicity. Patients were eligible as per the FDA-approved label of IV decitabine (MDS patients by FAB classification including CMML, or MDS IPSS Intermediate-1, 2 or high-risk patients). Clinical endpoints were best response as assessed by an independent expert panel according to International Working Group (IWG) 2006 response criteria, transfusion independence for at least 8 or 16 consecutive weeks, overall survival, and safety. Adverse events (AEs) were graded by Common Terminology Criteria for Adverse Events (CTCAE) v 4.03. Results: 138 subjects were randomized, of whom 133 were treated on study. The median age was 71.0 years (range 44-88), 65% were male, 88% MDS and 12% CMML, 43% were either red blood cells (RBCs) or platelets transfusion-dependent at baseline, 25% had poor-risk cytogenetics, and 42% had baseline bone marrow blasts >5%. At the data cutoff for the response analysis, the median duration of follow up was 12.6 m (range 9.3 to 20.5 m) with median number of treatment cycles of 8 (range 1 to 18). Of the 133 treated patients the best response was complete response (CR) in 28 patients (21%; 95% CI 15-29%), marrow (m)CR with hematological improvement (HI) in 20 patients (15%), mCR without HI in 23 patients (17.3%), and HI in 10 patients (7.5%) for an overall objective response (CR+mCR+HI) in 81 patients (61%; 95% CI 52-69%). Median duration of CR was 7.5 m (range 1.6 to 17.5 m), and median time to CR was 4.3 m (range 2.1 to 15.2 m). Of the 133 treated patients 27 (20%) went on to receive allogeneic hematopoietic cell transplant. Of the 57 patients who were either RBCs or platelets transfusion-dependent at baseline, 30 (53%) became transfusion independent for both RBCs and platelets for at least 8 consecutive weeks, and 19 (33%) were both RBCs and platelets transfusion independent for at least 16 consecutive weeks. Median survival has not been reached. Most common Treatment-Emergent AEs of Grade ≥3 regardless of causality were neutropenia in 51.5%, thrombocytopenia in 50%, anemia in 40%, febrile neutropenia in 26%, leukopenia in 21%, pneumonia in 12%, and sepsis in 7% of patients treated with oral decitabine/cedazuridine (excluding the IV decitabine cycle). Summary/Conclusions: Efficacy and safety from oral decitabine 35 mg/ cedazuridine 100 mg daily for 5 days every 28 days are consistent with clinical data from standard IV decitabine 20 mg/m2 daily for 5 days. Oral decitabine/cedazuridine is the only oral HMA with systemic exposure equivalent to its injectable drug. Further investigation of oral decitabine/cedazuridine in all-oral combination studies is warranted and underway. Disclosures Savona: BMS: Consultancy; AbbVie: Consultancy; Gilead: Consultancy; Karyopharm: Consultancy, Current equity holder in publicly-traded company; Ryvu: Consultancy; Boehringer Ingelheim: Patents & Royalties; Takeda: Consultancy, Research Funding; Incyte: Consultancy, Research Funding; Astex: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding. Griffiths:Celgene/BMS: Honoraria, Research Funding; Genentech Inc: Research Funding; Boston Biomedical: Honoraria; AbbVie Inc: Honoraria; Persimmune: Research Funding; Novartis: Honoraria, Research Funding; Alexion Pharmaceuticals: Honoraria, Research Funding; Astex Pharmceuticals: Research Funding. Zeidan:CCITLA: Other; Seattle Genetics: Consultancy, Honoraria; BeyondSpring: Consultancy, Honoraria; Taiho: Consultancy, Honoraria; Cardinal Health: Consultancy, Honoraria; Epizyme: Consultancy, Honoraria; Leukemia and Lymphoma Society: Other; Jazz: Consultancy, Honoraria; Trovagene: Consultancy, Honoraria, Research Funding; Ionis: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Research Funding; Astex: Research Funding; Daiichi Sankyo: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Research Funding; Otsuka: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Research Funding; Acceleron: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Boehringer-Ingelheim: Consultancy, Honoraria, Research Funding; Celgene / BMS: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria; ADC Therapeutics: Research Funding; Aprea: Research Funding; MedImmune/Astrazeneca: Research Funding; Cardiff Oncology: Consultancy, Honoraria, Other; Incyte: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria. Patel:DAVA Pharmaceuticals: Honoraria; France Foundation: Honoraria; Celgene: Consultancy, Speakers Bureau; Agios: Consultancy. Keating:Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Hoffman La Roche: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Merck: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy; Servier: Membership on an entity's Board of Directors or advisory committees; Shire: Membership on an entity's Board of Directors or advisory committees; Taiho: Membership on an entity's Board of Directors or advisory committees. Dao:Astex Pharmaceuticals, Inc.: Current Employment. Fazal:Jansen: Speakers Bureau; Gilead/Kite: Consultancy, Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Jazz Pharma: Consultancy, Speakers Bureau; Karyopham: Speakers Bureau; Celgene: Speakers Bureau; Glaxosmith Kline: Consultancy, Speakers Bureau; Incyte Corporation: Consultancy, Honoraria, Speakers Bureau; Agios: Consultancy, Speakers Bureau; Stemline: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Odenike:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astex Pharmaceuticals, NS Pharma, Gilead Sciences, Janssen Oncology, Oncotherapy, Agios, CTI/Baxalta, Aprea: Other: Institutional research funding; Astra Zeneca: Research Funding; Incyte: Other: Institutional research funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Impact Biomedicines: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Kantarjian:Abbvie: Honoraria, Research Funding; BioAscend: Honoraria; Delta Fly: Honoraria; Ascentage: Research Funding; Janssen: Honoraria; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Sanofi: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Immunogen: Research Funding; Aptitute Health: Honoraria; BMS: Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; Jazz: Research Funding; Oxford Biomedical: Honoraria; Amgen: Honoraria, Research Funding; Adaptive biotechnologies: Honoraria. DeZern:MEI: Consultancy; Celgene: Consultancy, Honoraria; Astex: Research Funding; Abbvie: Consultancy. Roboz:Novartis: Consultancy; Janssen: Consultancy; Celgene: Consultancy; Astex: Consultancy; Amphivena: Consultancy; Agios: Consultancy; Pfizer: Consultancy; Abbvie: Consultancy; Array BioPharma: Consultancy; Bayer: Consultancy; Celltrion: Consultancy; Eisai: Consultancy; Jazz: Consultancy; Roche/Genentech: Consultancy; Sandoz: Consultancy; Actinium: Consultancy; Argenx: Consultancy; Astellas: Consultancy; Daiichi Sankyo: Consultancy; AstraZeneca: Consultancy; Orsenix: Consultancy; Otsuka: Consultancy; Takeda: Consultancy; Trovagene: Consultancy; Cellectis: Research Funding; Jasper Therapeutics: Consultancy; Epizyme: Consultancy; Helsinn: Consultancy; MEI Pharma: Consultancy. Busque:Pfizer: Honoraria; BMS: Honoraria; Novartis: Honoraria. Wells:Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Leber:Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Otsuka Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda/Palladin: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Treadwell: Honoraria, Membership on an entity's Board of Directors or advisory committees; Lundbeck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Hao:Astex Pharmaceuticals, Inc.: Current Employment. Keer:Astex Pharmaceuticals, Inc.: Current Employment. Azab:Astex Pharmaceuticals, Inc.: Current Employment. Garcia-Manero:Acceleron Pharmaceuticals: Consultancy, Honoraria; AbbVie: Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; H3 Biomedicine: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Amphivena Therapeutics: Research Funding; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Onconova: Research Funding; Merck: Research Funding; Jazz Pharmaceuticals: Consultancy; Celgene: Consultancy, Honoraria, Research Funding; Novartis: Research Funding.

Intro: Iron overload (IO) reflected by elevated serum ferritins is associated with increased mortality in patients with myelodysplastic syndromes (MDS) with a threshold effect seen above 1000 ug/ml (Malcovati, JCO 2005). Ferritin is elevated due to transfusions, inflammation and ineffective erythropoiesis but is an imperfect metric of true iron overload. Elevated levels of oxidatively damaging non-transferrin bound iron (NTBI) and labile plasma iron (LBI) are not easily measured but correlate with transferrin saturation (TSAT) >70% and >80% respectively (de Swart, Haematological 2018). The relationship of TSAT with ferritin and MDS-related clinical outcomes has not been well-characterized. Objectives: We aimed to describe temporal trends in TSAT according to transfusion dependence and to determine if elevated TSAT correlates with ferritin levels, and/or predicts for clinical outcomes such as survival, infectious death and cardiac death in patients with MDS. Methods: Adult patients enrolled in the Canadian national MDS registry over 11.5 years and 15 centers were evaluated retrospectively. Mean, median and ranges for ferritin and TSAT were calculated at six (+/- 3) month intervals. General linear mixed model analysis with repeated measures per subject was used to evaluate changes in ferritin and TSAT over time. Transfusion density (TD) was calculated at landmark year 1 and 2 and was defined as the total number of units transfused/months elapsed since commencing transfusion dependence, with TD-low and TD-high defined as above or below median. Log-rank tests were used to detect survival differences among three transfusion groups (transfusion independent [TI], TD-low and TD-high), among three TSAT groups (TSAT 80% at enrolment), and among three ferritin groups (≤500ug/mL, 501-1000ug/mL and >1000ug/mL at enrolment). Results: A total of 718 patients from the MDS-CAN registry were included in the analysis. Patient characteristics including demographics, clinical and laboratory characteristics are summarized in Table 1. With a median follow up of 2.1 years, actuarial OS was 2.4 years. 17% developed AML and 61% of patients have died. AML, progressive disease, infection, cardiac causes, bleeding accounted for 26%, 20%, 19%, 9.6% and 6.34% of known causes of death respectively. 56% experienced infections (median 2/patient), 7% experienced a cardiac event and 43% were hospitalized at least once. Ferritin and TSAT were moderately correlated over time (r=0.63, p < 0.0001) (Figure 1A) with only 39% of all ferritins >1000ug/mL associating with a TSAT of >80%. The relationship between the 2337 serum ferritins (recorded over 42 months) and TSAT is shown in Figure 1B. Among all patients, ferritin significantly increased from enrolment up to 42 months (p Conclusion: Among a cohort of predominantly low-intermediate risk MDS patients, TSAT correlated only moderately with serum ferritins. TD patients, and in particular high transfusion-burden TD patients have inferior clinical outcomes compared to TI or low-transfusion burden TD patients. Further analyses to probe these relationships are ongoing including the effect of TSAT and iron chelation therapy on infectious deaths, and a multivariate analysis adjusting for other covariates. Disclosures Geddes: Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Keating:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Seattle Genetics: Consultancy; Sanofi: Membership on an entity's Board of Directors or advisory committees; Merck: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Hoffman La Roche: Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Taiho: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Shire: Membership on an entity's Board of Directors or advisory committees. Leber:Otsuka Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Treadwell: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda/Palladin: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Lundbeck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Shamy:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Storring:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Nevill:Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz Pharmaceuticals: Honoraria. Delage:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Elemary:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Chodirker:Hoffman Laroche: Honoraria. Leitch:AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Taiho: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Exjade: Speakers Bureau. Buckstein:Astex: Honoraria; Celgene: Honoraria; Takeda: Research Funding; Celgene: Research Funding; Novartis: Honoraria.

Background: The Canadian tyrosine kinase inhibitor (TKI) discontinuation trial, named "Treatment Free Remission Accomplished By Dasatinib " (NCT#02268370), has reported 56.8% molecular relapse-free survival (mRFS) rate at 12 months after imatinib (IM) discontinuation. MMR loss occurred quickly after IM discontinuation, typically within 2-4 months, while those who lost MR4 on two consecutive measurements tended to lose their molecular response more gradually. BCR-ABL transcript doubling time (DT) after TKI discontinuation is a reciprocal concept to transcript halving time following TKI therapy. Due to inter-individual differences in DT after TKI discontinuation, DT can be used as a potential biomarker to identify those patients at high-risk for TFR failure when measured before they experience a clinically significant event of molecular relapse. The present study has not only evaluated the kinetics of BCR-ABL transcript rise after IM discontinuation, but also explored the predictive/prognostic role of DT of BCR-ABL transcript level as an early predictor of TFR failure. Patients and methods: Changes of BCR-ABL1 transcript level in each patient were assessed monthly by estimating the number of days required for BCR-ABL1 to double from the previous expression level/measurement, termed the DT. Based on the BCR-ABL1 qPCR value taken monthly in the first 6 months after IM discontinuation, DT was calculated monthly, as x = ln(2)/K, where x is the DT and K is the fold BCR-ABL1 change from the previous value divided by the number of days between each measurement. K was determined as follows: K = [ln(b) - ln(a)]/t, where a is the BCR-ABL1 value of the previous measurement, b is the BCR-ABL1 at the relevant time point, and t is the number of days between measurements. The baseline qPCR level from the prior month to TKI discontinuation was referenced. The distribution of DT was assessed at each time point of DT measurement within the first 6 months. In order to define cut-off levels for BCR-ABL1 qPCR and DT for the first 6 months, multiple statistical parameters were taken into account including positive (PPV) and negative predictive value (NPV), accuracy and F1 score of DT value, resulting in the DT value of 12.75 days at 2 months as the optimal cut-off value of DT value. Patients were stratified into the 3 groups based on the DT value of 12.75 days at 2 months after IM discontinuation. The high-risk group was defined as the patients showing DT < 12.75 days but above 0, i.e. rapidly proliferating CML cells, implying a high risk for TFR failure with a shorter DT. The intermediate-risk group was defined as those patients with DT ≥ 12.75 days, i.e. more slowly proliferating CML cells implying intermediate risk for TFR failure. The low-risk group was defined as patients showing DT of zero or below, i.e. no increase in the size of the pool of cells expressing BCR-ABL, implying a low risk for TFR failure. The mRFS was analyzed for each of these risk groups at 6 monthly intervals after TKI discontinuation. Results: We compared the DT values of the patients that failed TFR with those from the patients who maintained their molecular response at last follow-up. The DT values at 2 months were much shorter in patients who failed TFR after IM cessation (median 8.32 days) compared to those who maintained molecular response (median 20.7 days; p The DT value of 12.75 days was defined as the optimal value for DT at 2 months with the NPV, PPV, accuracy and F1 score of 80.90%, 96.43%, 84.62% and 0.75, respectively, as the -log10(p-value), accuracy and F1 score reached a plateau at a DT of 12.75 days as presented in the Figure A. At a DT value of 12.75 days at 2 months after IM discontinuation, patients were stratified into 3 groups: high- (n=26), intermediate- (n=16) and low-risk groups (n=71; Figure B). With respect to mRFS rate, the high-risk group showed 7.7% mRFS rate at 12 months compared to 53.6% in the intermediate-risk group or 90.0% in the low-risk group (p Conclusion: Monthly assessment of DT based on the monthly BCR-ABL qPCR is useful to identify the patients with an imminent risk of molecular recurrence after IM cessation for TFR. Figure Disclosures Bence-Bruckler: Merck: Membership on an entity's Board of Directors or advisory committees. Keating:Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Hoffman La Roche: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy; Merck: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Shire: Membership on an entity's Board of Directors or advisory committees; Taiho: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Busque:Novartis: Honoraria; BMS: Honoraria; Pfizer: Honoraria. Delage:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Lipton:BMS: Consultancy, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria; Ariad: Consultancy, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Research Funding. Leber:Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Treadwell: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda/Palladin: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Lundbeck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Otsuka Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Introduction: CFI-400945 is a first-in-class, potent, selective, orally active inhibitor of Polo-like kinase 4 (PLK4) (Ki=0.26nM), a master regulator of centriole duplication, necessary for genomic integrity (Mason et al. Cancer Cell 2014; 26:163-76). CFI-400945 has activity in leukemia cell lines and primary leukemia samples including those with complex karyotype, inversion 3 and monosomy 7 (Minden. personal communications). This suggests that CFI-400945 may provide an effective treatment of patients with AML. The objectives of this phase 1 trial was to establish the safety, tolerability, and recommend phase II dose (RP2D) of CFI-400945 in patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Methods: Patients with relapsed/refractory AML or MDS and patients with untreated AML who refused induction chemotherapy or who are not candidates for intensive chemotherapy were eligible. Dose escalation followed a standard 3+3 design with a starting dose of 64 mg orally once daily. Plasma levels of CFI-400945 free base were measured on Days 1, 2, & 29 of Cycle 1 and Day 15 on all subsequent cycles. Peripheral blood and/or bone marrow were obtained at baseline, Day 8 of Cycle 1 and Day 1 of each subsequent cycle prior to dosing for pharmacodynamic monitoring. Safety assessments using the NCI CTCAE version 4.03 were performed. Results: From May 2018 to June 2019, nine patients have been enrolled on study across three pre-defined dose levels (64 mg [n=3], 96 mg [n=4], and 128 mg [n=2]). Three patients had untreated AML, five patients had relapsed/refractory AML and one patient had myelodysplastic syndrome/myeloproliferative disorder (MDS/MPN). Patient characteristics at diagnosis are outlined in Table 1. Six (67%) patients had baseline high throughput sequencing; the most frequent mutations were TP53 (33%), TET2 (33%), KRAS (33%) and DNMT3A (33%). A total of 20 cycles were administered with a median of 1 cycle (range, 0 to 7 cycles). The most common non-hematological drug related toxicities of any grade, which occurred in over 20%, were diarrhea (44%), headache (44%), colitis (33%), vomiting (33%), bilirubin increase (22%), dizziness (22%), fatigue (22%), and nausea (22%). One patient on the 96 mg dose level was not evaluable for DLT and hence, replaced. Both patients treated at the 128 mg/day dose level developed DLTs, consisting of grade 3 colitis and grade 5 sepsis and colitis. Pharmacokinetic profile indicated low interpatient variability between patients. Maximum exposure did not correlate with toxicity Six patients were evaluable for disease response. Two (33%) achieved complete remission (CR), 3 pts (50%) had stable disease (with one patient having a 78% reduction in marrow blast count). The patient with MDS/MPN who did not complete 1 cycle of therapy progressed to AML (Figure 1). Both patients who obtained a CR had an early response within 2 cycles. One CR has been durable for 218 days with no measurable residual disease (MRD) by flow cytometry. The additional patient, who obtained a CR with incomplete platelets recovery, with subsequent best response of CR, had a sustained response for 91 days before relapse was confirmed by bone marrow examination (Figure 1). Conclusion: Single agent CFI-400945 has activity in patients with poor risk AML. The RP2D in this population is 96 mg once daily. Dose expansion is occurring at the RP2D level. A phase 2 study with CFI-400945 single agent or in combination study with azacitidine or decitabine is planned. Disclosures Leber: Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Lundbeck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda/Palladin: Honoraria, Membership on an entity's Board of Directors or advisory committees; Treadwell: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Otsuka Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Bray:Treadwell Therapeutics: Current Employment; TIO Discovery: Current Employment. Gupta:Pfizer: Consultancy; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sierra Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol MyersSquibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Research Funding. Maze:Novartis: Honoraria; Pfizer: Consultancy; Takeda: Research Funding. McNamara:Novartis: Honoraria. Schimmer:Jazz: Honoraria; Otsuka: Honoraria; Medivir AB: Research Funding; AbbVie Pharmaceuticals: Other: owns stock ; Takeda: Honoraria, Research Funding; Novartis: Honoraria.

Introduction: Acute myeloid leukemia (AML) is driven by a subpopulation of leukemia stem cells (LSCs), which possess properties such as quiescence and self-renewal that are linked to therapy resistance and relapse. The LSC17 score was derived from genes differentially expressed between functionally validated LSC+ and LSC- fractions from 78 AML patients and is strongly associated with survival and response to standard therapy. A critical advantage of the LSC17 test over cytogenetic and molecular analysis is its rapid turnaround time (24-48h on a NanoString platform), providing clinicians with a rapid and powerful tool for upfront risk stratification. We have developed a clinical assay for the LSC17 score validated in a CAP/CLIA-lab setting. Methods: We conducted a prospective, multicenter validation and feasibility study to test the prognostic value of the LSC17 assay under real-world conditions in AML patients treated with curative intent. Patients with a possible new diagnosis of AML were eligible. Patients with a confirmed diagnosis of acute promyelocytic leukemia were excluded from analysis. Standard prognostic markers including cytogenetics, molecular studies and targeted sequencing using a standard AML panel were performed in parallel to the LSC17 score. Treatment was administered according to physician preference, based on patient history and results of standard prognostic assays, when available. Survival data was censored on June 14th, 2020. Results: 381 patients were recruited to the study between June 2016 and March 2020. 4 patients were excluded for quality control reasons (one sample had insufficient RNA and three samples failed quality control checks). 103 were excluded as they had alternative diagnoses. 84 patients were excluded because they did not receive intensive chemotherapy. LSC17 scores ranged from 0 to 1.25, and were classified as high or low according to the median score of 0.51 from a previously validated reference cohort (Ng et al, Nature 2016). Of the 190 patients included in this analysis, 84 had a low LSC17 score and 106 had a high LSC17 score. The median age was 61 years (range 18-79); 86 (45%) were female. When stratified according to ELN 2017 criteria, 48 (27%), 51 (29%), and 77 (44%) patients had favorable, intermediate, and adverse risk disease, respectively. Low LSC17 score was associated with normal cytogenetics (high vs low, 33% vs 58%; P We first considered response to induction chemotherapy (Table 1). 141 patients had standard induction chemotherapy with 3+7, 40 had Flag-IDA and 9 had CPX-351. High score patients had inferior responses to 3+7 with only 59% achieving complete remission (CR) after 1 cycle of chemotherapy compared to 96% of low score patients; responses for LSC17 high score patients were better in the Flag-IDA group with 80% achieving CR after 1 cycle. When considering overall CR rates after 2 cycles of induction, patients with a high LSC17 score were less likely to achieve CR (high vs low, 87% vs 98%; P=0.02). However, this difference was predominantly observed in patients treated with 3+7 (87% vs 99% CR rate in high vs low score patients, respectively); response rates to Flag-IDA were not significantly different between the 2 groups. Measurable residual disease (MRD) monitoring by flow cytometry was performed at the time of CR in 135 (71%) patients enrolled at Princess Margaret Cancer Centre. Patients with a high LSC17 score were significantly more likely to have MRD compared to low score patients (46% vs 10% respectively, P Conclusion: AML patients with a high LSC17 score have inferior outcomes following 3+7 induction chemotherapy. The LSC17 score should be considered as a tool to identify and stratify high-risk patients to alternative upfront therapies such as Flag-IDA. A risk adapted study is planned to validate these results. Disclosures Gupta: Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sierra Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy; Bristol MyersSquibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Research Funding. Maze:Novartis: Honoraria; Takeda: Research Funding; Pfizer: Consultancy. McNamara:Novartis: Honoraria. Schimmer:Medivir AB: Research Funding; AbbVie Pharmaceuticals: Other: owns stock ; Takeda: Honoraria, Research Funding; Novartis: Honoraria; Jazz: Honoraria; Otsuka: Honoraria. Leber:Takeda/Palladin: Honoraria, Membership on an entity's Board of Directors or advisory committees; Treadwell: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Otsuka Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees; Lundbeck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Tierens:Amgen: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Astellas Pharma: Membership on an entity's Board of Directors or advisory committees. Wang:Trilium therapeutics: Patents & Royalties: There is an existing license agreement between TTI and University Health Network and J.C.Y.W. may be entitled to receive financial benefits further to this license and in accordance with UHN's intellectual property policies. .

Background Red blood cell (RBC) transfusion dependence (TD) and anemia are associated with inferior quality of life (QOL) and survival in myelodysplastic syndromes (MDS). As part of a research programme to identify the optimal transfusion hemoglobin (Hb) threshold that translates into significantly improved QOL, we conducted a pilot randomized study of two transfusion algorithms (liberal versus restrictive) to determine the feasibility of a larger study. This trial was aligned with the REDDS study (ISRCTN26088319, Stanworth et al., BJH 2019) and followed the same pre-defined statistical analysis plan. Methods The study was undertaken at 3 cancer centers (NCT02099669). We included patients with MDS, CMML, low blast AML (20-30%) or myeloproliferative neoplasms who were TD (> 1 RBC/8 weeks x 16 weeks). Patients on disease modifying therapy for > 6 months were permitted only if they had remained stably RBC-TD with a life expectancy of > 3 months. Central randomization was to one of two RBC transfusion strategies over a 12-week period: Restrictive strategy to maintain Hb between 85 and 105g/L. To achieve this, 2 RBC units were transfused when Hb < 85 g/LLiberal strategy to maintain Hb between 110 and 120 g/L. To achieve this, 2 RBC units were transfused when Hb < 105 g/L and 1 unit for Hb 105-110 g/L. The first 4 weeks were considered a run-in period to achieve the target Hb. The primary outcomes of this feasibility study were The percentage compliance of Hb being within or above the target range of the assigned transfusion threshold (after the 4 week run-in). Feasibility was set at 70%.Achievement of at least a 15 g/L difference between the mean pre-transfusion Hb of the liberal and restrictive strategy groups. Secondary outcomes included changes and differences in QOL scores, rates of transfusion reactions and alloimmunizations, overall blood utilization and visit numbers and impact on serum ferritin. The primary analysis was intention to treat. The study was closed early due to COVID-19, with 28 patients randomized of planned 30. Results 30 patients were enrolled over 5 years and 28 patients randomized (n=15, liberal; n=13 restrictive). Median age was 74 (range 58-84), 26/28 had MDS or CMML and there were no significant imbalances in baseline disease and patient characteristics although patients in the restrictive group tended to have lower risk disease (IPSS-R very low + low 69% versus 53% liberal). Compared with the restrictive arm, liberal arm patients had more complete blood counts, were transfused more RBC units (only during the 4-week run-in) and were transfused at shorter intervals (Table 1). There were no differences in adverse events. Over the 12 weeks, the mean Hb value was 90 ± 4 g/L (restrictive) versus 101 ± 4 g/L (liberal), (p Adherence with QOL completion (minimum of 4 serial) was 93%. While sample sizes are small and comparisons exploratory, the area under the curve for several serial quality of life scores was numerically higher and the curve more stable for the liberal arm (EQ5D (figure 2), EORTC cognitive and emotional functioning). Similarly, a higher % of patients in the liberal arm achieved pre-defined clinically meaningful increases in several symptom and function domains (emotional, social, fatigue, dyspnea, financial problems). Discussion Whilst our study results did not meet our feasibility endpoints, this small randomized trial in MDS patients demonstrated clinically important differences in mean Hb achievable with different transfusion thresholds. Poor rates of compliance with Hb targets were clearly identified for patients in the liberal arm, suggesting a need to understand the barriers to protocol adherence in this arm prior to embarking on larger trials. Compared with the REDDS trial, we did not document a significant excess of RBC transfusions needed (post run-in period) to maintain the higher Hb threshold. Similar to REDDS, we did observe some signals of improved QOL with a liberal transfusion strategy. A formal analysis of pooled results with REDDS study patients is planned. (Funding, CCSRI grant QOLL-14 and MOSPI Fund 2014). Disclosures Buckstein: Novartis: Honoraria; Astex: Honoraria; Celgene: Honoraria; Celgene: Research Funding; Takeda: Research Funding. Prica:seattle genetics: Honoraria; Gilead: Honoraria; astra zeneca: Honoraria. Leber:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Otsuka Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Lundbeck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda/Palladin: Honoraria, Membership on an entity's Board of Directors or advisory committees; Treadwell: Honoraria, Membership on an entity's Board of Directors or advisory committees. Chodirker:Hoffman Laroche: Honoraria. Lin:Novartis: Research Funding; Pfizer: Honoraria. Callum:Octapharma: Research Funding; Canadian Blood Services: Research Funding.

Background: In ‘real-life', the Nordic score guides ESA use in lower-risk MDS with predicted response rates of 25% or 74%. As new treatments emerge, a more discriminating score is needed. Objectives: To validate existing ESA predictive scores and develop a new score that identifies non-responders. Methods: ESA-treated patients were identified in 3 MDS registries in Italy and Canada (FISM 555, GROM 233, MDS-CAN 208). Clinical and disease-related variables were captured. Nordic, MDS-CAN and IPSS-R-based ESA scores were calculated and documented ESA responses compared. Results: 996 ESA-treated patients were identified. Overall response rate(ORR) was 59%. The database was randomly divided into balanced derivation (n=463) and validation (n=462) cohorts. By multivariate analysis, transfusion independence, erythropoietin level

Summary Analyses suggest iron overload in red blood cell (RBC) transfusion-dependent (TD) patients with myleodysplastic syndrome (MDS) portends inferior overall survival (OS) that is attenuated by iron chelation therapy (ICT) but may be biassed by unbalanced patient-related factors. The Canadian MDS Registry prospectively measures frailty, comorbidity and disability. We analysed OS by receipt of ICT, adjusting for these patient-related factors. TD International Prognostic Scoring System (IPSS) low and intermediate-1 risk MDS, at RBC TD, were included. Predictive factors for OS were determined. A matched pair analysis considering age, revised IPSS, TD severity, time from MDS diagnosis to TD, and receipt of disease-modifying agents was conducted. Of 239 patients, 83 received ICT; frailty, comorbidity and disability did not differ from non-ICT patients. Median OS from TD was superior in ICT patients (5·2 vs. 2·1 years; P

The frailty index (FI) is based on the principle that the more deficits an individual has, the greater their risk of adverse outcomes. It is expressed as a ratio of the number of deficits present to the total number of deficits considered. We developed an MDS-specific FI using a prospective MDS registry and assessed its ability to add prognostic power to conventional prognostic scores in MDS. The 42 deficits included in this FI included measurements of physical performance, comorbidities, laboratory values, instrumental activities of daily living, quality of life and performance status. Of 644 patients, 440 were eligible for FI calculation. The median FI score was 0.25 (range 0.05-0.67), correlated with age and IPSS/IPSS-R risk scores and discriminated overall survival. With a follow-up of 20 months, survival was 27 months (95% CI 24-30.4). By multivariate analysis, age >70, FI, transfusion dependence, and IPSS were significant covariates associated with OS. The incremental discrimination improvement of the frailty index was 37%. We derived a prognostic score with five risk groups and distinct survivals ranging from 7.4 months to not yet reached. If externally validated, the MDS-FI could be used as a tool to refine the risk stratification of current clinical prognostication models.

The Bcl-2 family BH3 protein Bim promotes apoptosis at mitochondria by activating the pore forming proteins Bax and Bak and by inhibiting the anti-apoptotic proteins Bcl-XL, Bcl-2 and Mcl-1. Bim binds to these proteins via its BH3 domain and to the mitochondrial membrane by a carboxyl-terminal sequence (CTS). In cells killed by Bim, the expression of a Bim mutant in which the CTS was deleted (BimL-dCTS) triggered variable amounts of apoptosis that correlated with inhibition of anti-apoptotic proteins being sufficient to permeabilize mitochondria isolated from the same cells. Detailed analysis of the molecular mechanism demonstrated that BimL-dCTS inhibited Bcl-XL but did not activate Bax. Our examination of additional point mutants unexpectedly revealed that the CTS of Bim is required for physiological concentrations of Bim to activate Bax and that different residues in the CTS enable Bax activation and binding to membranes.

Hand mirror cell (HMC) leukemia is a variant of acute lymphoblastic leukemia previously described in the adult population where lymphoblasts manifest distinctive hand mirror morphologic features. HMC has been previously identified in 23% of childhood acute lymphoblastic leukemia patients, but its prognostic significance in children is not well understood. Hypercalcemia is also uncommon in childhood leukemias. Hypercalcemia associated with HMC leukemia has not been previously reported. We report a 5-year-old boy with HMC B-lymphoblastic leukemia who presented with hypercalcemia.