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Background: LY3410738 is a potent, selective, covalent, dual inhibitor of IDH1/2 mutations (IDH1/2m). LY3410738 binds covalently at a novel binding site, enabling continued potency in preclinical models in the setting of second site IDH resistance mutations. We present initial results from the first-in-human phase 1 dose escalation study of oral LY3410738 in patients (pts) with R/R IDH1/2m hematologic cancers. Methods: Dose escalation (3+3 design) evaluated LY3410738 monotherapy in IDH1/2m R/R AML (NCT04603001). Key objectives included determining the RP2D, safety, PK, PD (inhibition of plasma D-2-HG), and preliminary antitumor activity. Results: As of 28 July 2022, 114 pts including 108 R/R AML pts received LY3410738 dosed at 5-600 mg QD or 40-300 mg BID. Pts were median 73 years of age (range, 22-92) with a median of 2 prior therapies (range, 1-10); 29% received a prior IDH inhibitor and 58% a prior BCL2 inhibitor. Median time on treatment was 2.3 months (range, 0.1-15). No DLTs or treatment related deaths were observed. Treatment emergent adverse events ≥20% were diarrhea (22%), fatigue (21%), and anemia (20%). Differentiation syndrome was reported in 11 pts (10%); 4 grade 1/2 (4%), 7 grade 3 (6%). LY3410738 exposure was dose proportional. In pts with IDH1m cancers, LY3410738 achieved sustained D-2-HG inhibition at all dose levels including in pts who received prior IDH1 inhibitor. In pts with IDH2m cancers, a higher dose (≥150 mg daily dose) was required for D-2-HG inhibition. Responses were observed in both IDH1m and IDH2m AML (Table). Higher doses were required for IDH2m AML, especially IDH2 R140m pts. Efficacy appears higher in venetoclax naïve pts and limited in IDH inhibitor pre-treated pts. Conclusions: LY3410738 demonstrated a favorable safety profile with potent and sustained D-2-HG inhibition in pts with IDH1m R132, IDH2m R172, and IDH2m R140 mutations. Preliminary efficacy was also seen in all genotypes, in a dose dependent manner. RP2D evaluation is ongoing. Table: Response in R/R AML IDH Inhibitor Naive (N=68) IDH1 R132 IDH2 R172 IDH2 R140 No prior Venetoclax (n=13) Prior Venetoclax (n=19) Total (N=32) Low Dosesa (n=5) (High Dosesb) Total (N=13) Low Dosesa (n=9) (High Dosesb) Total (N=23) No prior Venetoclax (n=3) Prior Venetoclax (n=5) No prior Venetoclax (n=6) Prior Venetoclax (n=8) CR+CRh, n (%) 5 (38%) 2 (11%) 7 (22%) - 3 (100%) 2 (40%) 5 (38%) - 2 (33%) - 2 (9%) CR, n (%) 3 (23%) 2 (11%) 5 (16%) - 2 (67%) 2 (40%) 4 (31%) - 2 (33%) - 2 (9%) CRh, n (%) 2 (15%) - 2 (6%) - 1 (33%) - 1 (8%) - - - - CRc (CR+CRh+CRi/CRp), n (%) 6 (46%) 6 (32%) 12 (38%) - 3 (100%) 3 (60%) 6 (46%) - 2 (33%) - 2 (9%) MFLS, n (%) 1 (8%) 3 (16%) 4 (13%) 2 (40%) - - 2 (15%) 1 (11%) - - 1 (4%) IDH Inhibitor Pre-Treated (N=33) IDH1 R132 IDH2 R172 IDH2 R140 No prior Venetoclax (n=2) Prior Venetoclax (n=8) Total (N=10) Low Dosesa (n=6) (High Dosesb) Total (N=8) Low Dosesa (n=4) (High Dosesb) Total (N=15) No prior Venetoclax (n=1) Prior Venetoclax (n=1) No prior Venetoclax (n=3) Prior Venetoclax (n=8) CR+CRh, n (%) - - - - - - - - - 1 (13%) 1 (7%) CR, n (%) - - - - - - - - - - - CRh, n (%) - - - - - - - - - 1 (13%) 1 (7%) CRc (CR+CRh+CRi/CRp), n (%) - - - - - - - 1 (25%) - 1 (13%) 1 (7%) MLFS, n (%) - - - - - - - - - - - Among the 108 treated R/R AML pts, 101 were efficacy evaluable (42 IDH1 R132, 21 IDH2 R172, 38 IDH2 R140); 68 pts were IDH inhibitor naïve and 33 had received a prior IDH inhibitor treatment. Efficacy evaluable pts are those who had completed the first bone marrow assessment or had discontinued treatment prior to first bone marrow assessment aTotal daily low doses: ≤75 mg Arm A, ≤30 mg Arm B bTotal daily high doses: ≥150 mg Arm A, ≥60 mg Arm B Arm A: not requiring a strong CYP3A4 inhibitor Arm B: requiring a strong CYP3A4 inhibitor Citation Format: Courtney D. DiNardo, Pau Montesinos, Lina Benajiba, Ana Triguero, Christian Recher, Andre C. Schuh, Maël Heiblig, Ashish Bajel, Arnaud Pigneux, Juan M. Alonso-Domiguez, Amir T. Fathi, Carolyn Grove, Hsin-An Hou, Michael Heuser, Sarit Assouline, Shaun Fleming, Dong-Yeop Shin, Kendra Sweet, Olatoyosi Odenike, Jessica Altman, Melissa Gaik Ming Ooi, Lao Zhentang, Nobert Vey, Joshua Zeidner, Amandeep Salhotra, Eunice Wang, Gary Schiller, Kimmo Porkka, Tsila Zuckerman, Violaine Havelange, Brian A. Jonas, Sujaatha Narayanan, Jun Ho Jang, Je-Hwan Lee, Anna M. Szpurka, Dana Heirich, Hsiao Rong Chen, Violet Hanft, Junjie Zhao, Ivelina Gueorguieva, Yin Zhang, Eytan M. Stein. A first-in-human phase 1 study of LY3410738, a covalent inhibitor of mutant IDH, in advanced myeloid malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT026.

PURPOSE The B-cell lymphoma 2 (BCL-2) inhibitor venetoclax has an emerging role in acute myeloid leukemia (AML), with promising response rates in combination with hypomethylating agents or low-dose cytarabine in older patients. The tolerability and efficacy of venetoclax in combination with intensive chemotherapy in AML is unknown. PATIENTS AND METHODS Patients with AML who were ≥ 65 years (≥ 60 years if monosomal karyotype) and fit for intensive chemotherapy were allocated to venetoclax dose-escalation cohorts (range, 50-600 mg). Venetoclax was administered orally for 14 days each cycle. During induction, a 7-day prephase/dose ramp-up (days −6 to 0) was followed by an additional 7 days of venetoclax combined with infusional cytarabine 100 mg/m2 on days 1-5 and idarubicin 12 mg/m2 intravenously on days 2-3 (ie, 5 + 2). Consolidation (4 cycles) included 14 days of venetoclax (days −6 to 7) combined with cytarabine (days 1-2) and idarubicin (day 1). Maintenance venetoclax was permitted (7 cycles). The primary objective was to assess the optimal dose schedule of venetoclax with 5 + 2. RESULTS Fifty-one patients with a median age of 72 years (range, 63-80 years) were included. The maximum tolerated dose was not reached with venetoclax 600 mg/day. The main grade ≥ 3 nonhematologic toxicities during induction were febrile neutropenia (55%) and sepsis (35%). In contrast to induction, platelet recovery was notably delayed during consolidation cycles. The overall response rate (complete remission [CR]/CR with incomplete count recovery) was 72%; it was 97% in de novo AML and was 43% in secondary AML. During the venetoclax prephase, marrow blast reductions (≥ 50%) were noted in NPM1-, IDH2-, and SRSF2-mutant AML. CONCLUSION Venetoclax combined with 5 + 2 induction chemotherapy was safe and tolerable in fit older patients with AML. Although the optimal postremission therapy remains to be determined, the high remission rate in de novo AML warrants additional investigation (ANZ Clinical Trial Registry No. ACTRN12616000445471).

The BCL-2 inhibitor venetoclax combined with hypomethylating agents or low-dose cytarabine represents an important new therapy for older or unfit patients with acute myeloid leukemia (AML). We analyzed 81 patients receiving these venetoclax-based combinations to identify molecular correlates of durable remission, response followed by relapse (adaptive resistance), or refractory disease (primary resistance). High response rates and durable remissions were typically associated with NPM1 or IDH2 mutations, with prolonged molecular remissions prevalent for NPM1 mutations. Primary and adaptive resistance to venetoclax-based combinations was most commonly characterized by acquisition or enrichment of clones activating signaling pathways such as FLT3 or RAS or biallelically perturbing TP53. Single-cell studies highlighted the polyclonal nature of intratumoral resistance mechanisms in some cases. Among cases that were primary refractory, we identified heterogeneous and sometimes divergent interval changes in leukemic clones within a single cycle of therapy, highlighting the dynamic and rapid occurrence of therapeutic selection in AML. In functional studies, FLT3 internal tandem duplication gain or TP53 loss conferred cross-resistance to both venetoclax and cytotoxic-based therapies. Collectively, we highlight molecular determinants of outcome with clinical relevance to patients with AML receiving venetoclax-based combination therapies.

Antifungal prophylaxis can reduce morbidity and mortality from invasive fungal disease (IFD). However, its use needs to be optimised and appropriately targeted to patients at highest risk to derive the most benefit. In addition to established risks for IFD, considerable recent progress in the treatment of malignancies has resulted in the development of new 'at-risk' groups. The changing epidemiology of IFD and emergence of drug resistance continue to impact choice of prophylaxis, highlighting the importance of active surveillance and knowledge of local epidemiology. These guidelines aim to highlight emerging risk groups and review the evidence and limitations around new formulations of established agents and new antifungal drugs. It provides recommendations around use and choice of antifungal prophylaxis, discusses the potential impact of the changing epidemiology of IFD and emergence of drug resistance, and future directions for risk stratification to assist optimal management of highly vulnerable patients.

Measurable residual disease (MRD) is being recognised as an optimal method for assessing depth of response, identifying higher risk of relapse, and guiding response-based treatment paradigms for multiple myeloma (MM). Although MRD negativity is increasingly replacing complete response as the surrogate endpoint in clinical trials, its role in real-world practice is less established. We retrospectively analyzed EuroFlow MRD results from patients with newly diagnosed MM (NDMM) who underwent bortezomib, cyclophosphamide and dexamethasone (VCD) induction and high dose melphalan conditioned autologous stem cell transplant (ASCT) at the Alfred Hospital between January 2016 and December 2020. Next generation flow MRD evaluation was performed 3 months following ASCT using the standardised EuroFlow platform. 112 patients with available MRD data were identified to have received VCD induction followed by ASCT. Post ASCT MRD was undetectable in 28.6% of patients. Those who achieved MRD negativity had significantly longer progression free survival (PFS) than those with persisting MRD (24-month PFS of 85% [95% CI: 72.4-99.9%] vs 63% [95% CI: 52.9-75.3%], p = 0.022). Maintenance therapy was associated with improved PFS regardless of MRD status (24-month PFS of 100% [95% CI: NA, p = 0.02] vs 73% [95% CI: 53.1-99.6%] in MRD negative, and 75% [95% CI: 64.2-88.6%] vs 36% [95% CI: 20.9-63.2%, p = 0.00015] in MRD positive patients). Results from this retrospective study of real-world practice demonstrate that Euroflow MRD analysis following standard VCD induction and ASCT in NDMM is feasible and allows more accurate prognostication, providing a platform for response adaptive therapies.

BACKGROUND Measurable residual disease (MRD) monitoring in acute lymphoblastic leukemia (ALL) is an important predictive factor for patient outcome and treatment intensification. Molecular monitoring, particularly with quantitative polymerase chain reaction (qPCR) to measure immunoglobin heavy or kappa chain (Ig) or T-cell receptor (TCR) gene rearrangements, offers high sensitivity but accessibility is limited by expertise, cost, and turnaround time. Flow cytometric assays are cheaper and more widely available, and sensitivity is improved with multi-parameter flow cytometry at eight or more colors. METHODS We developed a 10-color single tube flow cytometry assay. Samples were subject to bulk ammonium chloride lysis to maximize cell yields with a target of 1 × 106 events. Once normal maturation patterns were established, patient samples were analyzed in parallel to standard molecular monitoring. RESULTS Flow cytometry was performed on 114 samples. An informative immunophenotype was identifiable in all 22 patients who had a diagnostic sample. MRD analysis was performed on 87 samples. The median lower limits of detection and quantification were 0.004% (range 0.0005%-0.028%) and 0.01% (range 0.001%-0.07%) respectively. Sixty-five samples had concurrent molecular MRD testing, with good correlation (r = 0.83, p

The prevalence of donor-derived leukemia is estimated to be 80.5 per 100 000 transplants, with a mean duration of transplant to incidence of donor-derived leukemia of 44 months (ranging from 2 to 2...

Although second-generation tyrosine kinase inhibitors (TKIs) show superiority in achieving deep molecular responses in chronic myeloid leukemia in chronic phase (CML-CP) compared with imatinib, the differing adverse effect (AE) profiles need consideration when deciding the best drug for individual patients. Long-term data from randomized trials of nilotinib demonstrate an increased risk of vascular AEs (VAEs) compared with other TKIs, although the natural history of these events in response to dose modifications or cessation has not been fully characterized. We retrospectively reviewed the incidence of nilotinib-associated AEs in 220 patients with CML-CP at 17 Australian institutions. Overall, AEs of any grade were reported in 95 patients (43%) and prompted nilotinib cessation in 46 (21%). VAEs occurred in 26 patients (12%), with an incidence of 4.1 events per 100 patient-years. Multivariate analysis identified age (P = .022) and dyslipidemia (P = .007) as independent variables for their development. There was 1 fatal first VAE, whereas the remaining patients either continued nilotinib (14 patients) or stopped it immediately (11 patients). Recurrent VAEs were associated with ongoing therapy in 7 of 14 who continued (with 2 fatal VAEs) vs 1 of 11 who discontinued (P = .04). Nineteen of the 23 evaluable patients surviving a VAE ultimately stopped nilotinib, of whom 14 received an alternative TKI. Dose reduction or cessation because of VAEs did not adversely affect maintenance of major molecular response. These findings demonstrate that in contrast to other AEs, VAEs are ideally managed with nilotinib cessation because of the increased risk of additional events with its ongoing use.

Therapy-related myeloid neoplasm (t-MN) is a rare but devastating consequence of chemotherapy and/or radiotherapy used for the treatment of solid cancers and various hematologic malignancies. Our current understanding of the etiology is that hematopoietic clones that are contemporaneous with the primary cancer and resistant to the cytotoxic exposure have the potential to undergo selective expansion and transformation to t-MN. Consequently, a large proportion of cases are associated with adverse risk factors, resulting in limited effective treatment options. Despite the emergence of some therapies with promising activity in t-MN, most effects are short-lived and allogeneic stem cell transplantation remains the only curative option for eligible patients. This review summarizes the current literature on t-AML and t-MDS, with the aim of providing practical recommendations on the clinical evaluation and management of these conditions.

BackgroundPatients unable to take azoles are a neglected group lacking a standardized approach to antifungal prophylaxis. We evaluated the effectiveness and safety of intermittent liposomal amphotericin B (L-AMB) prophylaxis in a heterogenous group of hematology patients.MethodsA retrospective cohort of all hematology patients who received a course of intravenous L-AMB, defined as 1 mg/kg thrice weekly from July 1, 2013 to June 30, 2018, were identified from pharmacy records. Outcomes included breakthrough-invasive fungal disease (BIFD), reasons for premature discontinuation, and acute kidney injury.ResultsThere were 198 patients who received 273 courses of L-AMB prophylaxis. Using a conservative definition, the BIFD rate was 9.6% (n = 19 of 198) occurring either during L-AMB prophylaxis or up to 7 days from cessation in patients who received a course. Probable/proven BIFD occurred in 13 patients (6.6%, 13 of 198), including molds in 54% (n = 7) and non-albicans Candidemia in 46% (n = 6). Cumulative incidence of BIFD was highest in patients with acute myeloid leukemia (6.8%) followed by acute lymphoblastic leukemia (2.7%) and allogeneic stem cell transplantation (2.5%). The most common indication for L-AMB was chemotherapy, or anticancer drug-azole interactions (75% of courses) dominated by vincristine, or acute myeloid leukemia clinical trials, followed by gut absorption concerns (13%) and liver function abnormalities (8.8%). Acute kidney injury, using a modified international definition, complicated 27% of courses but was not clinically significant, accounting for only 3.3% (9 of 273) of discontinuations.ConclusionsOur findings demonstrate a high rate of BIFD among patients receiving L-AMB prophylaxis. Pragmatic trials will help researchers find the optimal regimen of L-AMB prophylaxis for the many clinical scenarios in which azoles are unsuitable, especially as targeted anticancer drugs increase in use.

Combining venetoclax, a selective BCL2 inhibitor, with low-dose navitoclax, a BCL-XL/BCL2 inhibitor, may allow targeting of both BCL2 and BCL-XL without dose-limiting thrombocytopenia associated with navitoclax monotherapy. The safety and preliminary efficacy of venetoclax with low-dose navitoclax and chemotherapy was assessed in this phase I dose-escalation study (NCT03181126) in pediatric and adult patients with relapsed/refractory (R/R) acute lymphoblastic leukemia or lymphoblastic lymphoma. Forty-seven patients received treatment. A recommended phase II dose of 50 mg navitoclax for adults and 25 mg for patients Significance: In this phase I study, venetoclax with low-dose navitoclax and chemotherapy was well tolerated and had promising efficacy in patients with relapsed/refractory acute lymphoblastic leukemia or lymphoblastic lymphoma. Responses were observed in patients across histologic and genomic subtypes and in those who failed available therapies including stem cell transplant. See related commentary by Larkin and Byrd, p. 1324. This article is highlighted in the In This Issue feature, p. 1307

Improving survival outcomes in adult B-cell acute lymphoblastic leukemia (B-ALL) remains a clinical challenge. Relapsed disease has a poor prognosis despite the use of tyrosine kinase inhibitors (TKIs) for Philadelphia chromosome positive (Ph+ ALL) cases and immunotherapeutic approaches, including blinatumomab and chimeric antigen receptor T cells. Targeting aberrant cell survival pathways with selective small molecule BH3-mimetic inhibitors of BCL-2 (venetoclax, S55746), BCL-XL (A1331852), or MCL1 (S63845) is an emerging therapeutic option. We report that combined targeting of BCL-2 and MCL1 is synergistic in B-ALL in vitro. The combination demonstrated greater efficacy than standard chemotherapeutics and TKIs in primary samples from adult B-ALL with Ph+ ALL, Ph-like ALL, and other B-ALL. Moreover, combined BCL-2 or MCL1 inhibition with dasatinib showed potent killing in primary Ph+ B-ALL cases, but the BH3-mimetic combination appeared superior in vitro in a variety of Ph-like ALL samples. In PDX models, combined BCL-2 and MCL1 targeting eradicated ALL from Ph− and Ph+ B-ALL cases, although fatal tumor lysis was observed in some instances of high tumor burden. We conclude that a dual BH3-mimetic approach is highly effective in diverse models of high-risk human B-ALL and warrants assessment in clinical trials that incorporate tumor lysis precautions.

Background The social, contextual, and behavioral determinants that influence care in patients at risk for invasive fungal diseases (IFD) are poorly understood. This knowledge gap is a barrier to the implementation of emerging antifungal stewardship (AFS) programs. We aimed to understand the barriers and enablers to AFS, opportunities for improvement, and perspectives of AFS for hematology patients at a major medical center in Australia. Methods Semistructured, face-to-face interviews were conducted with 35 clinicians from 6 specialties (hematology, infectious diseases, pharmacy, nursing, radiology, respiratory), followed by thematic analysis mapped to a behavioral change framework. Results Access to fungal diagnostics including bronchoscopy was identified as the key barrier to rational prescribing. Collective decision making was the norm, aided by an embedded stewardship model with on-demand access to infectious diseases expertise. Poor self-efficacy/knowledge among prescribers was actually an enabler of AFS, because clinicians willingly deferred to infectious diseases for advice. A growing outpatient population characterized by frequent care transitions was seen as an opportunity for AFS but neglected by an inpatient focused model, as was keeping pace with emerging fungal risks. Ad hoc surveillance, audit, and feedback practices frustrated population-level quality improvement for all actors. Antifungal stewardship was perceived as a specialized area that should be integrated within antimicrobial stewardship but aligned with the cultural expectations of hematologists. Conclusions Antifungal stewardship is multifaceted, with fungal diagnostics a critical gap and outpatients a neglected area. Formal surveillance, audit, and feedback mechanisms are essential for population-level quality improvement. Resourcing is the next challenge because complex immunocompromised patients require personalized attention and audit of clinical outcomes including IFD is difficult.

The advent of pediatric inspired regimens has improved the outcome for younger adults with Acute Lymphoblastic Leukemia (ALL), however this comes at a considerable toxicity burden limiting its applicability in older adults. The advent of novel immunotherapies, such as Blinatumomab, an anti-CD19 targeting Bi-specific T-cell engager, has improved outcomes for adults with relapsed refractory and minimal residual disease (MRD) positive B-precursor (BCP) ALL. The Australasian Leukemia and Lymphoma Group (ALLG) undertook a phase 2 proof-of-concept study to explore the combination of Blinatumomab with reduced intensity chemotherapy in adults with newly diagnosed Ph- BCP ALL. Patients received an initial pre-phase of corticosteroids (Prednisolone 100mg/d, 5 days) followed by a low intensity chemotherapy debulking (Cyclophosphamide 150mg/m 2 BD D1-3, Vincristine 2mg IV D1, 11 and Dexamethasone 10mg/m 2 D1-4, D11-14). Following this patients received Blinatumomab at 9mcg/d days 1-7 and 28mcg/d days 8-28. A B cycle of Hyper-CVAD (Cytarabine 3g/m 2 BD for 4 doses and Methotrexate 1g/m 2 D1 with Methylprednisolone 50mg BD D1-3). Patients then received 3 alternating cycles of Blinatumomab (28mcg/d for 28 days) and B-cycles of Hyper-CVAD followed by 2-years of POMP maintenance in subjects not proceeding to allogeneic stem cell transplant (alloHSCT) which was at investigator discretion. MRD assessments by ASO-PCR were performed after the first B cycle, second B cycle and prior to maintenance therapy with an MRD response being a level of 10 -4 or less. This analysis is from a pre-specified interim analysis with a data cutoff of 29 th June 2021. 30 patients were enrolled with a median age of 51.7(range, 39.5 - 66.5 years) with 70% male subjects. ECOG performance score was 0 in 14 subjects, 1 in 12 and 2 in 4. High risk disease was identified in 5 subjects (1 t(4;11), 2 hypodiploid, 1 t(1;19) and 1 Ph-like). All patients attained a CR, with 28 at end of 1B and a further 2 at end of 2B. Of 26 patients evaluable for MRD, 70% had achieved an MRD response after cycle 1B and 83% at the end of cycle 2B. 15 patients have ceased study therapy; 6 patients died with progressive disease, 4 subjects exited to allogeneic stem cell transplant, 1 patient was withdrawn due to progressive disease, 1 had intolerable toxicity (peripheral neuropathy) and 1 at investigator discretion. There were no treatment related deaths. 15 remain on protocol in maintenance with the remainder having completed therapy. At data cut-off the median event free survival (EFS) was not reached (95% CI 8.3 months - NA) with an estimated 24 month EFS of 61.8% (95% CI 36.3 - 84.2%) (figure 1A), and similarly the median overall survival (OS) S was not reached (95% CI 21.0 months - NA) with an estimated 24 month OS of 68.6% (95% CI 41.5 - 85.1%)(figure 1B). This predicted EFS was greater than the pre-specified stopping rule of a 24-month EFS of 50%. 2 episodes of cytokine release syndrome (CRS) were recorded (1 grade 2, 1 grade 3) with the major toxicity being infective (53 episodes of sepsis, infection or febrile neutropenia) predominately related to chemotherapy cycles. 7 episodes of neurological toxicity were demonstrated (1 myelopathy and 4 peripheral neuropathy occurring during chemotherapy and 2 encephalopathy occurring during Blinatumomab administration). Overall, the combination of Blinatumomab with chemotherapy was tolerable and appeared efficacious with a high rate of remission and deep MRD responses observed. Responses appeared durable despite a low rate of alloHSCTin first remission. The major toxicity was infective and occurred in the context of chemotherapy cycles. Future developments from this protocol will emphasise further reduction in cytotoxic chemotherapy through incorporation of further novel agents to minimise this toxicity. Figure 1 Figure 1. Disclosures Fleming: Servier: Honoraria; Pfizer: Honoraria, Speakers Bureau; Abbvie: Honoraria, Speakers Bureau; Amgen: Honoraria, Research Funding, Speakers Bureau. Reynolds: Abbvie: Research Funding; Novartis AG: Current equity holder in publicly-traded company; Alcon: Current equity holder in publicly-traded company. Bajel: Abbvie, Amgen, Novartis, Pfizer: Honoraria; Amgen: Speakers Bureau. Yeung: BMS: Honoraria, Research Funding; Pfizer: Honoraria; Amgen: Honoraria; Novartis: Honoraria, Research Funding. Verner: Janssen-Cilag Pty Ltd: Research Funding. Wei: Abbvie, Amgen, Astellas, AstraZeneca, Celgene/BMS, Genentech, Janssen, MacroGenics, Novartis, Pfizer, and Servier: Honoraria; Novartis, Abbvie, Celgene/BMS: Speakers Bureau; Servier: Consultancy; Abbvie, Amgen, AstraZeneca, Celgene/BMS, Novartis, Servier and F. Hoffmann-La Roche: Research Funding; Abbvie, Amgen, Astellas, AstraZeneca, Celgene/BMS, Genentech, Janssen, MacroGenics, Novartis, Pfizer, and Servier: Membership on an entity's Board of Directors or advisory committees; Former employee of Walter and Eliza Hall Institute: Patents & Royalties: Prof. Andrew Wei is a former employee of the Walter and Eliza Hall Institute and is eligible for a fraction of the royalty stream related to Venetoclax. Greenwood: Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: Blinatumomab - usage in front-line therapy for Acute Lymphoblastic Leukaemia

Introduction Rising molecular measurable residual disease (MRD) is an arbiter of clinical relapse in acute myeloid leukemia (AML). Venetoclax (VEN) is active against IDH and NPM1 mutant (mt) AML as monotherapy (Konopleva et al, 2016 and Chua et al, 2020) and can yield MRD negative remission when combined with low dose ara-C (LDAC) in patients unfit for intensive chemotherapy (DiNardo and Tiong et al, 2020). In a retrospective study, we showed that VEN in combination with hypomethylating agents or LDAC could erase rising NPM1mt MRD in 6/7 cases (Tiong et al, 2020). We now present a prospective phase 2 study of VEN and LDAC in patients with molecular MRD failure or oligoblastic AML relapse. Methods This multicenter phase 2 study stratified patients into oligoblastic relapse (marrow blasts 5-15%; Group A), or molecular MRD failure (Group B) as defined by the European LeukemiaNet (ELN) recommendations (failure confirmed by 2 interval samples) (Schuurhuis et al, 2018). Patients received VEN 600 mg (days 1-28) and LDAC 20 mg/m 2 (days 1-10). Primary objectives were morphologic or MRD response (≥1 log reduction) in groups A and B, respectively. Key secondary objectives were allogeneic hematopoietic cell transplantation (allo-HCT) realization and relapse-free (RFS) and overall survival (OS). The study had Alfred Health ethics approval (196/19). NPM1mt and other fusion transcript levels (per 10 5 ABL) from bone marrow were analyzed by RT-qPCR, IDH1 and IDH2 by Bio-Rad TM droplet digital PCR. Results The study enrolled 32 patients, with 29 evaluable (cut-off date 15/7/21). The median age of the study population was 62 years; 79% had intermediate cytogenetic risk, 66% NPM1mt, 11% FLT3-ITD and 37% IDH1/IDH2 mt. Most received prior intensive chemotherapy (93%) and 2 (7%) allo-HCT in first remission. Median interval from AML diagnosis to study entry was 12.6 months (Table 1). After a median follow-up of 7.9 months, patients had received a median of 3 cycles (range 1-14) of VEN-LDAC, with 13 patients ongoing. The main reasons for treatment cessation were allo-HCT (n=10; 34%) or donor lymphocyte infusion (n=2; 7%), treatment failure (n=3) or an adverse event (n=1). Hematologic complete/incomplete response (CR/CRi) among 11 patients with oligoblastic relapse (group A) was 73% and included: CR (n=5, 45%) or CRi (n=3, 27%), with an additional patient with morphologic leukemia-free state and 2 patients with stable disease. Overall, across both groups, median RFS and OS were not reached, estimated at 78% and 91% at 1 year, respectively. Among 18 patients with molecular MRD failure (group B) treated with VEN+LDAC, molecular response (≥1 log reduction) was achieved in 72%, and the RFS and OS were estimated at 83% and 87% at 1 year, respectively. Analysis of a sub-group of patients with NPM1mt (n=18); 6 and 12 from Groups A and B, respectively revealed the median NPM1mt transcript level at study entry to be 8985 copies (IQR 826, 94,431). A molecular response was achieved in 14 (78%) patients, including 9 (50%) with complete molecular remission (CR MRD-), with most responses achieved within 2 cycles of therapy (Figure B). Treatment with VEN-LDAC was generally well tolerated, with 15 serious adverse events reported within the first 2 cycles, including infection (n=6; 19%) and febrile neutropenia (n=3; 9%). Only one subject discontinued treatment due to stroke. Conclusions In this prospective study, in patients with first oligoblastic relapse or MRD failure, VEN in combination with LDAC induced a high rate of molecular MRD remission that was rapidly achieved, resulting in a high rate of survival at 12-months (>90%) and with low toxicity. Follow-up is ongoing to determine the durability of response. Treatment of patients with MRD or early clinical failure may represent an attractive clinical trial setting for investigation of novel, non-intensive AML therapies. This approach will be investigated in a future multi-arm, precision-based platform trial called INTERCEPT (Investigating Novel Therapy to Target Early Relapse and Clonal Evolution as Pre-emptive Therapy in AML). Figure 1 Figure 1. Disclosures Tiong: Servier: Consultancy, Speakers Bureau; Amgen: Speakers Bureau; Pfizer: Consultancy. Hiwase: Novartis: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees. Fleming: Amgen Inc: Research Funding. Bajel: Amgen: Speakers Bureau; Abbvie, Amgen, Novartis, Pfizer: Honoraria. Fong: Amgen, BMS: Speakers Bureau; Amgen: Research Funding; AbbVie, Amgen, Novartis, Pfizer, Astellas: Honoraria. Wei: Celgene/BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Agios: 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, Speakers Bureau; Genentech: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: 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; Roche: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Macrogenics: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: This presentation will discuss the use of venetoclax in targeting measurable residual disease and early relapse of acute myeloid leukemia.

Dasatinib has shown superiority over imatinib in achieving molecular responses (MRs) in chronic phase chronic myeloid leukemia but with a different toxicity profile, which may impact its overall benefit. Reported toxicities include pleural effusions and pulmonary hypertension, and although the incidence of these events is well described, response to therapy and impact of dose modifications on toxicity has not been comprehensively characterized in a real-world setting. We retrospectively reviewed the incidence of dasatinib adverse events in 212 chronic phase chronic myeloid leukemia patients at 17 Australian institutions. Adverse events were reported in 116 patients (55%), most commonly pleural effusions (53 patients, 25%), which was the predominant cause of permanent drug cessation. Age and dose were risk factors for pleural effusion (P < .01 and .047, respectively). Recurrence rates were higher in those who remained on 100 mg compared with those who dose reduced (P = .041); however, recurrence still occurred at 50 mg. Patients who developed pleural effusions were more likely to have achieved MR4.5 after 6 months of dasatinib than those without effusions (P = .008). Pulmonary hypertension occurred in 5% of patients, frequently in association with pleural effusion, and was reversible upon dasatinib cessation in 6 of 7 patients. Dose reductions and temporary cessations had minimal impact on MR rates. Our observations suggest that by using the lowest effective dose in older patients to minimize the effusion risk, dose modification for cytopenias, and care with concomitant antiplatelet therapy, the necessity for permanent dasatinib cessation due to toxicity is likely to be minimal in immunologically competent patients.

Background: Disease relapse remains the main cause of mortality after allogeneic stem cell transplantation (allo-SCT) for patients with myeloid malignancies. Loss of donor chimerism (DC) is commonly used as a biomarker of impending relapse, which allows the initiation of pre-emptive therapies such as withdrawal of immunosuppression or donor lymphocyte infusion (DLI). Surprisingly, there are few if any direct comparisons of peripheral blood CD34+ and CD3+ DC as biomarkers to predict relapse. We hypothesized that loss of CD34+ DC may be a more direct measure of impending relapse given most myeloid malignancies express CD34. Methods: We prospectively measured peripheral blood CD34+ and CD3+ DC on days 30, 60, 90, 120 and 180 following allo-SCT for patients with AML (n=113) or MDS (n=23) transplanted at a single centre between July 2011 and November 2019. Chimerism analysis was performed using purified cell subsets isolated from 60 mL peripheral blood using PCR-based amplification of short tandem repeats (STRs). The goal of this retrospective analysis was to compare the value of CD3+ and CD34+ DC for predicting relapse. Institutional practice for CD34+ DC below 80% included a bone marrow biopsy to identify morphologic relapse and donor lymphocyte infusion. Statistical analysis was performed with R 3.5.2 (The R project for Statistical computing) or GraphPad (v8.2.0). Results: Overall, 41 of 136 (30%) patients had morphologic relapse at a median time of 153 days after allo-SCT (range 50-1742). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of CD3+ and CD34+ donor chimerism for morphologic relapse is shown in Figure 1A. CD34+ DC outperformed CD3+ DC in all criteria, irrespective of the percentage chosen. Furthermore, a concurrent reduction in CD34+ DC was seen in almost all patients (14/16 at the 80% level) that had a fall in CD3+ DC. A fall in CD34+ DC below 80% was highly predictive for relapse, with a 5 year relapse free survival of only 17% compared with 80% for those that maintained DC > 80% for the first 180 days (Figure 1B). To determine the clinical utility of CD34+ DC, we measured the time to relapse in those patients that had a fall in DC without morphologic relapse at the time of DC measurement (Figure 1A). Based upon our institutional trigger of CD34+ DC < 80%, the median time to relapse was 49 days in 22 patients. In contrast, a CD34+ DC < 90% had a much longer time to relapse (71 days). However, this longer lead time would come at the price of unnecessary intervention in almost half of all patients as the PPV for CD34+ DC < 90% was only 55%. Loss of CD3+ DC had the longest lead time (> 70 days), however it was only useful up to 10 (24%) of all relapses. Finally, DLI administered for CD34+ DC < 80% maintained durable remission (> 12 months) in only 2 of 19 patients. Conclusion: This is the largest comparison of peripheral blood CD34+ and CD3+ DC following allo-SCT. Our results show that monthly monitoring of CD34+ DC in the first 6 months after allo-SCT is a more useful biomarker than CD3+ DC for predicting relapse in patients allografted for AML or MDS. The level of CD34+ DC chosen to trigger intervention should be guided by characteristics of the intervention such as toxicity and expected response time. Given the relative ineffectiveness of DLI for CD34+ < 80%, we suggest that 90% may provide greater time for immunologic responses. Figure Legend (A) Characteristics of different levels of CD3 and CD34 DC at any time in the first 180 days post-allo-SCT. Number of patients that fulfil the level in the total cohort of 136 patients. Number of patients before relapse indicates the number that do not have morphologic relapse at the time of DC measurement. Median days before relapse is shown for those patients. (B) Relapse free survival of patients according to CD34+ DC > 80% (blue line) or < 80% (yellow line) in the first 180 days. Disclosures Spencer: AbbVie, Celgene, Haemalogix, Janssen, Sanofi, SecuraBio, Specialised Therapeutics Australia, Servier and Takeda: Consultancy; Celgene, Janssen and Takeda: Speakers Bureau; Amgen, Celgene, Haemalogix, Janssen, Servier and Takeda: Research Funding; AbbVie, Amgen, Celgene, Haemalogix, Janssen, Sanofi, SecuraBio, Specialised Therapeutics Australia, Servier and Takeda: Honoraria. Wei:Celgene: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; MacroGenics: Consultancy, Honoraria; Servier: Consultancy, Honoraria, Research Funding; Walter and Eliza Hall Institute: Other: former employee and receives a fraction of its royalty stream related to venetoclax; Pfizer: Honoraria; Genentech: Honoraria; Astra Zeneca: Honoraria, Research Funding; AbbVie Inc.: Consultancy, Honoraria, Research Funding.

In acute myeloid leukemia (AML), risk stratification based on cytogenetics and mutation profiling is essential but remains insufficient to select the optimal therapy. Accurate biomarkers are needed to improve prognostic assessment. We analyzed RNA sequencing and survival data of 430 AML patients and identified HMGA2 as a novel prognostic marker. We validated a quantitative PCR test to study the association of HMGA2 expression with clinical outcomes in 358 AML samples. In this training cohort, HMGA2 was highly expressed in 22.3% of AML, mostly in patients with intermediate or adverse cytogenetics. High expression levels of HMGA2 (H + ) were associated with a lower frequency of complete remission (58.8% vs 83.4%, P 0.001), worse 3-year overall survival (OS, 13.2% vs 43.5%, P 0.001) and relapse-free survival (RFS, 10.8% vs 44.2%, P 0.001). A positive HMGA2 test also identified a subgroup of patients unresponsive to standard treatments. Multivariable analyses showed that H + was independently associated with significantly worse OS and RFS, including in the intermediate cytogenetic risk category. These associations were confirmed in a validation cohort of 260 patient samples from the UK NCRI AML17 trial. The HMGA2 test could be implemented in clinical trials developing novel therapeutic strategies for high-risk AML.

// Peter Tan 1 , Ing Soo Tiong 1, 2 , Shaun Fleming 1 , Giovanna Pomilio 2 , Nik Cummings 3 , Mark Droogleever 4 , Julie McManus 3 , Anthony Schwarer 5 , John Catalano 6 , Sushrut Patil 1 , Sharon Avery 1 , Andrew Spencer 1, 2 and Andrew Wei 1, 2 1 Malignant Haematology and Stem Cell Transplantation Service, Alfred Hospital, Melbourne, Australia 2 Australian Centre for Blood Diseases, Monash University, Melbourne, Australia 3 Department of Pathology, Alfred Hospital, Melbourne, Australia 4 Faculty of Medicine, University of Amsterdam, Amsterdam, The Netherlands 5 Eastern Health Clinical School, Monash University, Box Hill, Australia 6 Clinical Haematology, Frankston Hospital, Frankston, Australia Correspondence to: Andrew Wei, email: andrew.wei@monash.edu Keywords: acute myeloid leukemia, everolimus, azacitidine, mTOR, clinical trial Received: October 21, 2016 Accepted: November 20, 2016 Published: November 29, 2016 ABSTRACT Therapeutic options are limited in relapsed/refractory acute myeloid leukemia (AML). We evaluated the maximum tolerated dose (MTD) and preliminary efficacy of mammalian target of rapamycin (mTOR) inhibitor, everolimus (days 5–21) in combination with azacitidine 75 mg/m 2 subcutaneously (days 1–5 and 8–9 every 28 days) in 40 patients with relapsed ( n = 27), primary refractory ( n = 11) or elderly patients unfit for intensive chemotherapy ( n = 2). MTD was not reached following everolimus dose escalation (2.5, 5 or 10 mg; n = 19) to the 10 mg dose level which was expanded ( n = 21). Major adverse events (grade > 2) were mostly disease-related: neutropenia (73%), thrombocytopenia (67%), mucositis (24%) and febrile neutropenia (19%). Overall survival (OS) of the entire cohort was 8.5 months, and overall response rate (ORR; including CR/CRi/PR/MLFS) was 22.5%. Furthermore, a landmark analysis beyond cycle 1 revealed superior OS and ORR in patients receiving 2.5 mg everolimus with azoles, compared to those without azoles (median OS 12.8 vs. 6.0 months, P = 0.049, and ORR 50% vs. 16%, P = 0.056), potentially due to achievement of higher everolimus blood levels. This study demonstrates that everolimus in combination with azacitidine is tolerable, with promising clinical activity in advanced AML.

In acute myeloid leukemia (AML), risk stratification based on cytogenetics and mutation profiling is essential but remains insufficient to select the optimal therapy. Accurate biomarkers are needed to improve prognostic assessment. We analyzed RNA sequencing and survival data of 430 AML patients and identified HMGA2 as a novel prognostic marker. We validated a quantitative PCR test to study the association of HMGA2 expression with clinical outcomes in 358 AML samples. In this training cohort, HMGA2 was highly expressed in 22.3% of AML, mostly in patients with intermediate or adverse cytogenetics. High expression levels of HMGA2 (H + ) were associated with a lower frequency of complete remission (58.8% vs 83.4%, P < 0.001), worse 3-year overall survival (OS, 13.2% vs 43.5%, P < 0.001) and relapse-free survival (RFS, 10.8% vs 44.2%, P < 0.001). A positive HMGA2 test also identified a subgroup of patients unresponsive to standard treatments. Multivariable analyses showed that H + was independently associated with significantly worse OS and RFS, including in the intermediate cytogenetic risk category. These associations were confirmed in a validation cohort of 260 patient samples from the UK NCRI AML17 trial. The HMGA2 test could be implemented in clinical trials developing novel therapeutic strategies for high-risk AML.

Precursor-B acute lymphoblastic leukemia (B-ALL) is an aggressive hematological malignancy. Relapsed disease has a poor prognosis despite improved outcomes with tyrosine kinase inhibitors (TKIs) and immunotherapeutic approaches such as CAR-T cells. Targeting cell survival with small molecule BH3 mimetic inhibitors of BCL-2, BCL-XL or MCL1 is an emerging therapeutic option. We report that dual BH3 mimetic targeting of BCL-2/MCL1 is strongly synergistic in SUPB15, BV173, MUTZ5 and MHHCALL4 B-ALL cell lines and was more effective than single BH3 mimetic combinations with dexamethasone (DXM) or TKIs (dasatinib/ruxolitinib). In patient samples, combined BCL-2/MCL1 targeting lowered the LC50 by 10-1000 fold (LC50

In this Phase 1b study, the safety and tolerability of maintenance therapy, comprising lenalidomide (0-25 mg, days 5-25) in combination with azacitidine (50-75 mg/m(2) , days 1-5) every 28 d, was explored in 40 patients with acute myeloid leukaemia (AML) in complete remission after chemotherapy. Eligibility included AML in first complete remission (CR1) with adverse risk karyotype (n = 8), fms-related tyrosine kinase 3-internal tandem duplication (FLT3-ITD) (n = 5), age ≥60 years (n = 31) or AML in second remission (CR2) (n = 14). Dose-limiting toxicity was not reached. Common toxicities were haematological, infection, injection pain, constipation, fatigue and diarrhoea. In CR1, median relapse-free (RFS) and overall survival (OS) was 12 and 20 months, respectively. In CR2, median RFS was 11 months, with median OS not yet reached. Among 29 patients with intermediate cytogenetic risk, RFS was 50% at 24 months. There were five patients with concomitant FLT3-ITD and nucleophosmin (NPM1) mutation; none have relapsed and all are still alive after 17-39 months. Maintenance lenalidomide/azacitidine augmented the function of cytotoxic T lymphocytes, particularly in patients with NPM1 mutation. The lenalidomide/azacitidine maintenance combination was effective in suppressing residual DNA (cytosine-5-)-methyltransferase 3 alpha (DNMT3A)-positive disease, resulting in sustained remission in patients with concurrent NPM1 mutation. Azacitidine/lenalidomide as maintenance therapy for high-risk AML warrants further exploration.

There is a strong argument for the use of antifungal prophylaxis in high-risk patients given the significant mortality associated with invasive fungal disease, the late identification of these infections, and the availability of safe and well-tolerated prophylactic medications. Clinical decisions about which patients should receive prophylaxis and choice of antifungal agent should be guided by risk stratification, knowledge of local fungal epidemiology, the efficacy and tolerability profile of available agents, and estimates such as number needed to treat and number needed to harm. There have been substantial changes in practice since the 2008 guidelines were published. These include the availability of new medications and/or formulations, and a focus on refining and simplifying patient risk stratification. Used in context, these guidelines aim to assist clinicians in providing optimal preventive care to this vulnerable patient demographic.

Introduction/Background Mucositis is a common complication of high-dose melphalan (HDM) used before autologous stem cell transplantation (ASCT) for multiple myeloma (MM). Mucositis rates are influenced by previous chemotherapy (CT) exposure. We examined the effect of induction therapy before ASCT on ASCT mucositis rates. Patients and Methods Patients undergoing first 200 mg/m 2 HDM ASCT were assessed. Those receiving 2 , or those with previous ASCT were excluded. Patients were evaluated depending on type of induction therapy (CT, immunomodulatory drug [IMiD], or proteasome inhibitor [PI]) before ASCT. A case record review was performed and data collected on response to induction, rates of Grade 3/4 mucositis, and days of total parenteral nutrition (TPN) or parenteral opiate analgesia. Results One hundred twenty-eight patients with ASCT were assessed. Induction therapy was CT- (n = 62), IMiD- (n = 51), or PI-based (n = 15) therapy. Patient characteristics were overall similar, including median age, MM stage, and CD34 + cell dose. IMiD-based therapy patients had lower rates of mucositis (33% vs. 53%; P = .03) and less opiate requirements (10% vs. 31%; P = .02) compared with those treated with CT. Rates of mucositis and opiate use in the PI group were not different to the CT cohorts (33% vs. 53%; P = .6 and 13% vs. 31%; P = .13), likely due to concurrent anthracycline exposure. TPN usage was similar (CT, 42%; IMiD, 35%; and PI, 20%), as was neutropenia duration and antibiotic usage. Conclusion Patients treated with IMiD-based regimens before HDM ASCT had significantly lower rates of mucositis than those treated with CT-based therapy. There were too few patients who received PI therapy to evaluate the effect.

Prototheca species are achlorophyllus algae. Prototheca wickerhamii and Prototheca zopfii cause human disease. In immunocompetent individuals, they cause soft tissue infections and olecranon bursitis, but in transplant recipients, these organisms can cause disseminated disease. We report a fatal case of disseminated P. zopfii infection in an hematopoietic stem cell transplant (HSCT) recipient with bloodstream infection and involvement of multiple soft tissue sites. We review all previous cases of protothecosis in HSCT reported in the literature. Protothecosis is uncommon after HSCT, but has a disseminated presentation that is frequently fatal. It is commonly misidentified as a yeast. Tumor necrosis factor-alpha inhibitors and contamination of central venous catheters may contribute to development of protothecosis. Optimal treatment approaches are yet to be defined. New agents such as miltefosine may be possible future therapies.

Background - Conventional chemotherapy for adults with Acute Lymphoblastic Leukaemia (ALL) is associated with considerable treatment-related toxicity. Blinatumomab is a CD19/CD3 targeting bi-specific T-cell engager that has demonstrated promising efficacy in relapsed/refractory ALL, and in combination with chemotherapy in newly diagnosed patients. Preliminary studies also suggest less toxicity and good efficacy (CR/CRh 66%) when delivered as induction to older adults (median age 75) with newly diagnosed B-ALL (Advani, ASH 2018). Of responders, Minimal Residual Disease (MRD) negativity in this trial was achieved in 92%. Given this, the Australasian Leukaemia & Lymphoma Group (ALLG) has explored the potential for upfront Blinatumomab as induction for younger adults with Ph- B-lineage Acute Lymphoblastic Leukaemia, alternating with CNS-directed chemotherapy cycles. Aim - To assess response to therapy of the first 10 patients enrolled on this study by molecular MRD analysis as a surrogate measure of short-term efficacy of this combination. Method - The ALLG ALL8 study (ACTRN12617000084381) is a phase II proof-of-concept front-line study for patients fit for treatment with a Hyper-CVAD-like regimen (between 40-65 years) with newly diagnosed Ph- B-lineage ALL. Those with CNS positive disease are excluded. Patients receive a steroid pre-phase (Prednisolone 100mg daily for 7 days) followed by a disease debulking phase of cyclophosphamide 150mg/m2 BD day 1-3, vincristine 2mg day 1 & 11 and dexamethasone 10mg/m2 day 1-4 and 11-14. Patients then receive alternating cycles of Blinatumomab (at 9mcg/d for the first 7 days of cycle 1 followed by 28mcg/d until day 28) with B-cycles of Hyper-CVAD (Methotrexate 1g/m2 day 1, Cytarabine 3g/m2 BD day 2,3, Methylprednisolone 50mg BD day 1-3) (figure 1). All patients receive intrathecal prophylaxis with methotrexate, cytarabine and hydrocortisone prior to blinatumomab treatment blocks and day 1 and 8 of each B-cycle until a total of 8 doses were administered. At the completion of therapy, high-risk patients (MLL translocations, hypodiploid, complex karyotype or MRD positive at TP3) are recommend to proceed to allogeneic stem cell transplant while others receive 24 months of POMP maintenance. Minimal residual disease analysis was performed at a centralised EuroMRD accredited laboratory utilising Taqman probes and patient specific PCR primers targeted at immunoglobulin heavy chain or T-cell receptor (Ig/TCR) gene rearrangements. MRD positivity was defined as a detectable level of ≥ 1 x 10-4. Results - The following results are based upon the first 10 patients enrolled on ALL8. Median age of 54.7 years (range 43 to 66 years) and 70% were male. Median ECOG PS was 0 (range 0 - 2). 6 patients had an abnormal karyotype, 2 high-risk (one with hypodiploid karyotype, one with t(1;19). Median white cell count at diagnosis was 3.36 x 109/L (range 1.95 - 12.05 x 109/L). All patients (10/10) attained CR/CRi following induction therapy with no treatment related deaths. At the end of the induction phase (MRD TP1) 4 out of 10 had attained MRD negativity, 2 had detectable unquantifiable MRD and 4 were MRD positive. By the end of the 1st consolidation cycle (MRD TP2) 1 additional patient had become MRD negative and 1 MRD positive patient had become MRD unquantifiable. 1 patient was not evaluable at TP2 being withdrawn prior to this, 2 do not have TP2 available at this time (1 being MRD negative at TP1, 1 with unquantifiable low-level MRD). One patient had MRD increase between TP1 and TP2, this subject had a hypodiploid karyotype. Thus, by completion of 1st consolidation an aggregate of 7 out of 10 patients were MRD negative or had unquantifiable low-level MRD, 3 remaining MRD positive (with 1 MRD progression). Updated results will be presented at the meeting. Conclusion - Front-line therapy with Blinatumomab in combination with chemotherapy is feasible in adults and results in high levels of MRD response by the end of the first consolidation block with the majority of MRD negative responses attained after the first treatment block. Despite early incorporation of Blinatumomab into this treatment protocol, MRD progression was seen in one patient with high-risk cytogenetic abnormalities. Disclosures Fleming: Astellas: Membership on an entity's Board of Directors or advisory committees; Ariad: Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria. Reynolds:Novartis Australia: Honoraria; Novartis AG: Equity Ownership; AUSTRALASIAN LEUKAEMIA & LYMPHOMA GROUP (ALLG): Consultancy; Alfred Health: Employment, Other: Biostatistician for trials funded by the Australian government and Abbvie, Amgen, Celgene, GSK, Janssen-Cilag, Merck, Novartis, Takeda, but sponsored by Alfred Health.. Nguyen:Australasian Leukaemia & Lymphoma Group: Employment. Yeung:Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Pfizer: Honoraria; Amgen: Honoraria. Greenwood:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Verner:Janssen-Cilag Pty Ltd: Research Funding. Bajel:AbbVie: Membership on an entity's Board of Directors or advisory committees, Other: travel funding. Wei:AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: AHW is a former employee of the Walter and Eliza Hall Institute and receives a fraction of its royalty stream related to venetoclax, Research Funding, Speakers Bureau; Astellas: Honoraria, 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, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Macrogenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: 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; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra Zeneca: Honoraria, Research Funding; Janssen: Honoraria. OffLabel Disclosure: Blinatumomab is not currently approved for the front-line treatment of adults with Ph- B-ALL

Background: Prognosis of Acute Myeloid Leukaemia (AML) is guided by chromosomal and molecular profiling. Standard regression approaches may not be optimal for identifying complex gene-gene interactions. Aims: We investigated use of machine-learning (ML) by recursive partitioning (RP) and random forest (RF) analysis on two large AML datasets to develop a hierarchical prognostic risk model. Methods: This study included 2074 non-APL AML cases aged ≤70 from National Taiwan University Hospital (NTUH; n=759) and the German-Austrian AML Study Group (AMLSG; n=1315)(Table 1). Statistical analysis performed in R (version 3.5.1) with RP performed using the rpart (version 4.1-13); RF analysis used randomForestSRC (version 2.7.0) with complexity parameter 0.0007 and minimum subgroup 20. Missing data imputed, branch-points without prognostic significance trimmed. Kaplan-Meier analysis utilized for survival with patients with incomplete data excluded from survival analysis. Overall survival (OS) outcomes were classified into Good (5-year OS >55%), Intermediate (5-year OS >40 - 55%), Poor (5-year OS >20 - 40%) and Very Poor (5-year OS ≤20%). Results: Median age 48 (range 15 - 70) years. Cohorts were evenly matched except higher rate of allograft in complete remission (CR) or CR with incomplete blood count recovery (CRi) for AMLSG (31% vs 18%)(Table 1). CR or CRi achieved in 70%. Median OS for the entire cohort 2.3 years. Machine-learning to develop a prognostic decision-tree for OS based on random 2:1 selection of cases (training-set) and validated on remaining cases (validation-set). Each cohort produced similar RP-trees (Figure 1). Through ML, a decision tree was developed that hierarchically categorized cytogenetic and molecular factors into groupings that most accurately predicted survival. AML features used in the tree included complex karyotype (CK), inv(16), CEBPAdmut, inv(3)/t(3;3), FLT3-ITD, spliceosome mutations (U2AF1, SRSF2 or SF3B1), NPM1mut (in the absence of FLT3-ITD), t(8;21), and other AML identified by single genetic lesions including MLL translocations, NRASmut, isolated TP53mut or isolated ASXL1mut (Table 2). 261 patients (12.5%) were not classified by the model due to incomplete cytogenetic or mutational data and were excluded from survival analysis. In the CK group, a negative effect on prognosis (CR and OS) was conferred by inclusion of high-risk monosomies or structural chromosomal alterations (-7, del(7q), chromosome 17 abnormalities, -5 or del(5q)) or TP53mut, whereas CK cases lacking these lesions had a better prognosis (median OS 5.5 vs 25.1 months, p0.5) also associated with very poor prognosis in the absence of both spliceosome lesions and NPM1mut (median OS 11.6 months). A poor prognostic category comprising triple mutant FLT3-ITD, NPM1mut and DNMT3Amut was identified (median OS 13.2 vs 41.7 months, p=0.002). Cases with spliceosome mutation (SRSF2, U2AF1, SF3B1) had a very poor prognosis if accompanied by either ASXL1mut or potential heterozygous loss of ASXL1 on 20q (either by del(20q) or -20)(median OS 11.8 vs 21.6 months, p=0.003). In NPM1mut disease, ML identified good prognosis for patients who with NRASmut, whereas co-mutation with IDH1mut conferred an intermediate prognosis. In patients with t(8;21) AML, KIT mutations identified patients with intermediate prognosis (median OS 36.6 months vs NR, p=0.02). There were 49 patients (2.4%) with RUNX1mut not categorized to other groups and RUNX1mutper se did not emerge as a prognostic discriminator in this analysis. In comparison to ELN2017 classification, ML reclassified 45% of cases - 30% good, 26% intermediate, 26% poor and 18% very poor (compared to 39% good, 31% intermediate and 30% poor). In establishing the accuracy of predicting death at any time for individual cases the error rate was 35% for our ML model compared to 45% for the ELN2017 classification and 51% for ELN based cytogenetic analysis alone. Conclusion: By combining large datasets from two AML groups using machine-learning, an AML decision-tree was able to refine the accuracy of assessing survival prognosis compared to ELN 2017 classification by providing further prognostic granularity. Disclosures Fleming: Celgene: Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria; Ariad: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees. Tsai:Astellas, BMS, Celgene, Chugai, Johnson & Johnson, Kirin, Novartis, Pfizer, Roche, Takeda: Honoraria; Celgene: Research Funding. Döhner:Celgene, Novartis, Sunesis: Honoraria, Research Funding; AbbVie, Agios, Amgen, Astellas, Astex, Celator, Janssen, Jazz, Seattle Genetics: Consultancy, Honoraria; AROG, Bristol Myers Squibb, Pfizer: Research Funding. Döhner:Daiichi: Honoraria; Jazz: Honoraria; Novartis: Honoraria; Celgene: Honoraria; Janssen: Honoraria; CTI Biopharma: Consultancy, Honoraria. Papaemmanuil:Celgene: Research Funding. Tien:Abbvie: Honoraria; Celgene: Research Funding; Roche: Honoraria; Johnson &Johnson: Honoraria; Daiichi Sankyo: Honoraria; Pfizer: Honoraria; Alexion: Honoraria; Roche: Research Funding; Novartis: Honoraria; Celgene: Honoraria; BMS: Honoraria. Reynolds:Alfred Health: Employment, Other: Biostatistician for trials funded by the Australian government and Abbvie, Amgen, Celgene, GSK, Janssen-Cilag, Merck, Novartis, Takeda, but sponsored by Alfred Health.; AUSTRALASIAN LEUKAEMIA & LYMPHOMA GROUP (ALLG): Consultancy; Novartis AG: Equity Ownership; Novartis Australia: Honoraria. Wei:Amgen: 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; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria; Astra Zeneca: Honoraria, Research Funding; Astellas: Honoraria, 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, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Macrogenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: AHW is a former employee of the Walter and Eliza Hall Institute and receives a fraction of its royalty stream related to venetoclax, Research Funding, Speakers Bureau. Hou:Abbvie, Astellas, BMS, Celgene, Chugai, Daiichi Sankyo, IQVIA, Johnson & Johnson, Kirin, Merck Sharp & Dohme, Novartis, Pfizer, PharmaEssential, Roche, Takeda: Honoraria; Celgene: Research Funding.

Background:The small molecule BCL-2 inhibitor Venetoclax (VEN) has emerged as a promising frontline therapy in combination with low dose cytarabine (LDAC) or hypomethylating agents in older patients with acute myeloid leukemia (AML)(DiNardo et al, Lancet Oncol 2018, Blood 2019; Wei et al,JCO 2019). The anti-leukemic activity of single agent VEN as monotherapy in newly diagnosed AML is unknown. This information would be useful for studies considering VEN as a maintenance therapy. We have previously presented preliminary outcomes from a phase 1b/2 study: Chemotherapy and Venetoclax in Elderly AML Trial (CAVEAT), which incorporated a 7-day single agent VEN run-in phase prior to combination with chemotherapy (Wei et al, ASH 2018). The study procedures incorporated a bone marrow assessment performed at study screening and on day 8, prior to commencement of chemotherapy (Figure 1A). This allowed us to explore the single agent activity of venetoclax on bone marrow blasts in treatment naïve patients with AML and to assess molecular dynamics of response. Methods:The CAVEAT trial included 51 de novo or secondary patients with AML aged ≥65 years and considered fit for intensive chemotherapy. The study enrolled patients to 5 VEN dose cohorts (50-100-200-400-600mg). VEN was administered on days 1-14 during induction. Chemotherapy commenced on day 8, with a 7-day VEN monotherapy pre-phase. Molecular studies:a 54-gene myeloid NGS panel (Illumina TruSight) and MassARRAY MALDI-TOF mass spectrometry was performed on DNA extracted from bone marrow aspirates. FLT3-ITD testing was by fragment analysis, PCR and capillary electrophoresis. Minimal residual disease (MRD) testing was performed by digital droplet PCR for IDH mutations (assay sensitivity: 10-4-10-5). Results: A total of 46 patients had paired BM assessments at screening and on day 8 for comparison. A ≥50% relative reduction in BM blasts was recorded in 13/46 (28%) patients. Figure 1B shows the relative BM blast reduction stratified by molecular subgroups. Patients with NPM1(n=9) or IDH2 (n=8) mutation achieved greater BM blast reductions (median of 56% and 55%, respectively) than IDH1 (n=6), TP53 (n=10) or FLT3-ITD (n=5) mutant cases (median of 37%, 17% and 7%, respectively). Three NPM1 mutant cases with Clinically, complete remission (CR) and CR with incomplete count recovery (CRi) rates after chemotherapy were seen for the following mutations: NPM1(80%), IDH2 (100%), IDH1 (62%) and TP53 (36%) (Figure 1D). Despite all four response-evaluable patients with FLT3-ITD achieving CR/CRi, 3/4 relapsed with detectable FLT3-ITD (at 0.8, 1.5 and 12.3 months respectively). Median survival for each genomic sub-group were NPM1 (12.5m), IDH2 (not reached), IDH1 (6.1m),TP53 (3.8m), FLT3-ITD (5.5m). CyTOF analyses for changes in BCL-2 family expression are underway and results will be presented at the meeting. Conclusion: Treatment naïve NPM1 and IDH2 mutant AML blasts are highly sensitive to VEN alone and combination with cytarabine and anthracycline chemotherapy results in a high clinical response rate. TP53 and FLT3-ITD mutant cases were more resistant and outcomes were poor despite VEN combined with chemotherapy. Figure 1 Disclosures Reynolds: Alfred Health: Employment, Other: Biostatistician for trials funded by the Australian government and Abbvie, Amgen, Celgene, GSK, Janssen-Cilag, Merck, Novartis, Takeda, but sponsored by Alfred Health.; AUSTRALASIAN LEUKAEMIA & LYMPHOMA GROUP (ALLG): Consultancy; Novartis AG: Equity Ownership; Novartis Australia: Honoraria. Fong:Pfizer: Consultancy, Speakers Bureau; Amgen: Consultancy, Research Funding, Speakers Bureau; Astellas: Consultancy; Novartis: Speakers Bureau. Ting:NHMRC: Research Funding. Fleming:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria; Pfizer: Honoraria; Ariad: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees. Moujalled:Walter and Eliza Hall Institute of Medical Research: Patents & Royalties: Share in venetoclax royalties . Ivey:Novartis: Honoraria. Roberts:AbbVie: Research Funding; Janssen: Research Funding; Walter and Eliza Hall Institute: Employment, Patents & Royalties: receives a fraction of its royalty stream related to venetoclax. Wei:AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: AHW is a former employee of the Walter and Eliza Hall Institute and receives a fraction of its royalty stream related to venetoclax, Research Funding, Speakers Bureau; Astellas: Honoraria, 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, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Macrogenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: 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; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra Zeneca: Honoraria, Research Funding; Janssen: Honoraria. OffLabel Disclosure: Venetoclax is a BCL-2 inhibitor that is FDA-approved in some indications. This presentation will focus on correlative study results in the CAVEAT trial which combines venetoclax with modified intensive chemotherapy in AML, which is not an approved indication.