Search

Allogeneic hematopoietic stem cell transplantation (HSCT) is the gold standard curative therapy for infants and children with many inborn errors of immunity (IEI), but adolescents and adults with IEI are rarely referred for transplant. Lack of published HSCT outcome data outside small, single-center studies and perceived high risk of transplant-related mortality have delayed the adoption of HSCT for IEI patients presenting or developing significant organ damage later in life. This large retrospective, multicenter HSCT outcome study reports on 329 IEI patients (age range, 15-62.5 years at HSCT). Patients underwent first HSCT between 2000 and 2019. Primary endpoints were overall survival (OS) and event-free survival (EFS). We also evaluated the influence of IEI-subgroup and IEI-specific risk factors at HSCT, including infections, bronchiectasis, colitis, malignancy, inflammatory lung disease, splenectomy, hepatic dysfunction, and systemic immunosuppression. At a median follow-up of 44.3 months, the estimated OS at 1 and 5 years post-HSCT for all patients was 78% and 71%, and EFS was 65% and 62%, respectively, with low rates of severe acute (8%) or extensive chronic (7%) graft-versus-host disease. On univariate analysis, OS and EFS were inferior in patients with primary antibody deficiency, bronchiectasis, prior splenectomy, hepatic comorbidity, and higher hematopoietic cell transplant comorbidity index scores. On multivariable analysis, EFS was inferior in those with a higher number of IEI-associated complications. Neither age nor donor had a significant effect on OS or EFS. We have identified age-independent risk factors for adverse outcome, providing much needed evidence to identify which patients are most likely to benefit from HSCT. ispartof: BLOOD vol:140 issue:14 pages:1635-1649 ispartof: location:United States status: published

BACKGROUND: Janus kinase (JAK) inhibitors approved for myelofibrosis provide spleen and symptom improvements but do not meaningfully improve anaemia. Momelotinib, a first-in-class inhibitor of activin A receptor type 1 as well as JAK1 and JAK2, has shown symptom, spleen, and anaemia benefits in myelofibrosis. We aimed to confirm the differentiated clinical benefits of momelotinib versus the active comparator danazol in JAK-inhibitor-exposed, symptomatic patients with anaemia and intermediate-risk or high-risk myelofibrosis.METHODS: MOMENTUM is an international, double-blind, randomised, controlled, phase 3 study that enrolled patients at 107 sites across 21 countries worldwide. Eligible patients were 18 years or older with a confirmed diagnosis of primary myelofibrosis or post-polycythaemia vera or post-essential thrombocythaemia myelofibrosis. Patients were randomly assigned (2:1) to receive momelotinib (200 mg orally once per day) plus danazol placebo (ie, the momelotinib group) or danazol (300 mg orally twice per day) plus momelotinib placebo (ie, the danazol group), stratified by total symptom score (TSS; FINDINGS: 195 patients were randomly assigned to either the momelotinib group (130 [67%]) or danazol group (65 [33%]) and received study treatment in the 24-week randomised treatment period between April 24, 2020, and Dec 3, 2021. A significantly greater proportion of patients in the momelotinib group reported a 50% or more reduction in TSS than in the danazol group (32 [25%] of 130 vs six [9%] of 65; proportion difference 16% [95% CI 6-26], p=0·0095). The most frequent grade 3 or higher treatment-emergent adverse events with momelotinib and danazol were haematological abnormalities by laboratory values: anaemia (79 [61%] of 130 vs 49 [75%] of 65) and thrombocytopenia (36 [28%] vs 17 [26%]). The most frequent non-haematological grade 3 or higher treatment-emergent adverse events with momelotinib and danazol were acute kidney injury (four [3%] of 130 vs six [9%] of 65) and pneumonia (three [2%] vs six [9%]).INTERPRETATION: Treatment with momelotinib, compared with danazol, resulted in clinically significant improvements in myelofibrosis-associated symptoms, anaemia measures, and spleen response, with favourable safety. These findings support the future use of momelotinib as an effective treatment in patients with myelofibrosis, especially in those with anaemia.FUNDING: Sierra Oncology.

We report the clinical presentation and risk factors for survival in 175 patients with myeloproliferative neoplasms (MPN) and COVID-19, diagnosed between February and June 2020. After a median follow-up of 50 days, mortality was higher than in the general population and reached 48% in myelofibrosis (MF). Univariate analysis, showed a significant relationship between death and age, male gender, decreased lymphocyte counts, need for respiratory support, comorbidities and diagnosis of MF, while no association with essential thrombocythemia (ET), polycythemia vera (PV), and prefibrotic-PMF (pre-PMF) was found. Regarding MPN-directed therapy ongoing at the time of COVID-19 diagnosis, Ruxolitinib (Ruxo) was significantly more frequent in patients who died in comparison with survivors (p=0.006). Conversely, multivariable analysis found no effect of Ruxo alone on mortality, but highlighted an increased risk of death in the 11 out of 45 patients who discontinued treatment. These findings were also confirmed in a propensity score matching analysis. In conclusion, we found a high risk of mortality during COVID-19 infection among MPN patients, especially in MF patients and/or discontinuing Ruxo at COVID-19 diagnosis. These findings call for deeper investigation on the role of Ruxo treatment and its interruption, in affecting mortality in MPN patients with COVID-19.

Resumen Antecedentes y objetivo La mielofibrosis es una neoplasia mieloproliferativa cronica infrecuente. Nuestro objetivo fue describir las caracteristicas clinico-biologicas, el tratamiento y el curso evolutivo de los pacientes con mielofibrosis en Espana. Material y metodos Se analizaron 1.000 pacientes del Registro Espanol de Mielofibrosis diagnosticados de mielofibrosis primaria (n = 641) o secundaria (n = 359). Resultados La mediana de edad era de 68 anos. La frecuencia de sintomatologia constitucional, anemia moderada o severa (Hb Conclusiones la mielofibrosis es una enfermedad invalidante que afecta sobre todo a personas de edad avanzada y cuyo tratamiento es fundamentalmente sintomatico. A pesar de su heterogeneidad clinica se dispone de modelos pronosticos utiles para la seleccion de candidatos a trasplante.

BACKGROUND AND OBJECTIVE MYELOFIBROSIS: is an infrequent chronic myeloproliferative neoplasm. We aimed to describe the clinico-biological characteristics, treatment, and evolutive course of myelofibrosis patients in Spain.; MATERIAL AND METHODS: A total of 1,000 patients from the Spanish Registry of Myelofibrosis diagnosed with primary (n=641) or secondary (n=359) myelofibrosis were analysed.; RESULTS: Median age was 68 years. The frequency of constitutional symptoms, moderate to severe anaemia (Hb

Recent studies have shown a suboptimal humoral response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA) vaccines in patients diagnosed with hematologic malignancies; however, data about cellular immunogenicity are scarce. The aim of this study was to evaluate both the humoral and cellular immunogenicity 1 month after the second dose of the mRNA-1273 vaccine. Antibody titers were measured by using the Elecsys and LIAISON anti–SARS-CoV-2 S assays, and T-cell response was assessed by using interferon-γ release immunoassay technology. Overall, 76.3% (184 of 241) of patients developed humoral immunity, and the cellular response rate was 79% (184 of 233). Hypogammaglobulinemia, lymphopenia, active hematologic treatment, and anti-CD20 therapy during the previous 6 months were associated with an inferior humoral response. Conversely, age >65 years, active disease, lymphopenia, and immunosuppressive treatment of graft-versus-host disease (GVHD) were associated with an impaired cellular response. A significant dissociation between the humoral and cellular responses was observed in patients treated with anti-CD20 therapy (the humoral response was 17.5%, whereas the cellular response was 71.1%). In these patients, B-cell aplasia was confirmed while T-cell counts were preserved. In contrast, humoral response was observed in 77.3% of patients undergoing immunosuppressive treatment of GVHD, whereas only 52.4% had a cellular response. The cellular and humoral responses to the SARS-CoV-2 mRNA-1273 vaccine in patients with hematologic malignancies are highly influenced by the presence of treatments such as anti-CD20 therapy and immunosuppressive agents. This observation has implications for the further management of these patients., The authors also thank the Cellex Foundation for providing research facilities and equipment and the CERCA Programme/Generalitat de Catalunya for institutional support.

MMB, an oral JAK1/2 and ACVR1/ALK2 inhibitor, was evaluated (vs DAN) in a pivotal phase 3 study of MF patients previously treated with a JAK inhibitor (JAKi). This subgroup analysis evaluated MOMENTUM patients with baseline platelet counts ≤150 × 10Eligibility: Primary or post-ET/PV MF; DIPSS high risk, Int-2, or Int-1; total symptom score (TSS) ≥10; hemoglobin10 g/dL; prior JAKi ≥90 days, or ≥28 days if RBC transfusions ≥4 units in 8 weeks or Grade 3/4 thrombocytopenia, anemia, or hematoma; palpable spleen ≥5 cm; platelets ≥25 × 10TSS response (≥50% reduction from baseline) rate at week 24. Secondary endpoints at week 24: transfusion independence (TI) rate, splenic response rate (SRR; ≥25% volume reduction from baseline), TSS change from baseline, SRR (≥35% reduction), and rate of zero transfusions since baseline.Mean baseline TSS: 29 MMB, 26 DAN, hemoglobin: 8.1 MMB, 7.8 DAN g/dL, and platelets: 74 × 10In symptomatic, anemic, and thrombocytopenic MF patients, MMB was superior to DAN for symptom responses, transfusion requirements, and spleen responses with comparable safety and favorable survival. MMB may address a critical unmet need in thrombocytopenic MF patients. NCT04173494.

7015 Background: Ruxolitinib (RUX), a Janus kinase (JAK) 1/2 inhibitor, is the current standard of care for patients (pts) with myelofibrosis (MF) that improves splenomegaly and disease symptoms with limited impact on disease biology. Many pts lose response over time, highlighting an unmet need for novel therapies. Navitoclax (NAV) is an oral, small-molecule inhibitor of BCL-XL and BCL-2 that has a synergistic effect when used in combination with JAK inhibitors to enhance apoptosis. This ongoing, open-label, multicenter, phase 2 trial (NCT03222609) is evaluating the efficacy and safety of NAV with/without RUX in pts with MF. Here, we report results from JAK inhibitor-naïve pts treated with NAV+RUX. Methods: Enrolled pts had primary or secondary MF with splenomegaly (DIPSS ≥INT-1) and did not receive prior JAK-2 therapy or bromodomain and extraterminal motif (BET) inhibitors. Pts initiated NAV at 100 mg QD or 200 mg QD if baseline (BL) platelet count was ≤150 × 109/L or >150 × 109/L, respectively. RUX was given BID with starting dose based on BL platelet count per local label. The primary endpoint was spleen volume reduction of ≥35% (SVR35) from BL at wk 24. Key secondary endpoints were ≥50% reduction in total symptom score (TSS50), bone marrow (BM) fibrosis reduction, and anemia response. Adverse events (AEs) were monitored throughout the study. Results: As of Oct 04, 2021, 32 pts received NAV+RUX. Median duration of f/u was 6.1 (range, 1.9 ─ 18.6) mos. 28 (88%) pts received NAV 200 mg and 4 (13%) received 100 mg OD. Median age was 69 (44 ─ 83) yrs, and median spleen volume was 1889.08 cm3 (645.6 ─ 7339.6). Median NAV and RUX exposures were 24.1 (5.1 ─ 80.9) and 20.1 (0.1 ─ 80.1) wks, respectively. 31 (97%) pts reported ≥1 AE (Grade ≥3 AEs, 25 [78%]; serious AEs, 6 [19%]). Most common Grade ≥3 AEs were anemia (34%), thrombocytopenia (31%), and neutropenia (19%). 3 (9%) and 2 (6%) pts reported an AE leading to NAV and RUX discontinuation, respectively, and 2 (6%; 1 PD, 1 cardiac disorder unrelated to NAV) AEs led to death ≤30 days after last NAV dose. SVR35 was achieved by 52% of evaluable pts at wk 24 (SVR35 in INT-2, 50%; HR, 33%) and by 76% at any time on treatment (Table). Median time to first SVR35 was 12.1 (11 ─ 47) wks. Conclusions: The combination of NAV+RUX was well tolerated and demonstrated early and robust reductions in spleen volume, anemia, and BM fibrosis in pts without prior JAK-2 inhibitor exposure. SVR35, TSS50, and BM fibrosis improved over time. Clinical trial information: NCT03222609. [Table: see text]

7061 Background: MMB, an oral JAK1/2 and ACVR1/ALK2 inhibitor, showed clinical activity on MF symptoms, RBC transfusion requirements (anemia), and spleen volume in the SIMPLIFY trials, including in MF patients (pts) with thrombocytopenia. MOMENTUM is a pivotal phase 3 study of symptomatic and anemic MF pts previously treated with a JAK inhibitor (JAKi) testing MMB vs DAN. This analysis evaluated MOMENTUM pts with baseline (BL) platelet counts (PLT) ≤150 x 109/L. Methods: Eligibility: Primary or post-ET/PV MF; DIPSS high risk, Int-2, or Int-1; MF Symptom Assessment Form Total Symptom Score (MFSAF TSS) ≥10; Hgb 9/L. JAKi taper and washout was ≥21 days. Randomization: 2:1 to MMB 200 mg QD plus DAN placebo or DAN 600 mg QD plus MMB placebo for 24 wks. Primary endpoint: TSS response (≥50% reduction from BL) rate at wk 24. Key secondary endpoints, assessed sequentially at wk 24: RBC transfusion independence (TI) rate, splenic response rate (SRR; ≥25% reduction in volume from BL), change from BL in TSS, SRR (≥35% reduction from BL) and rate of zero transfusions since BL. Results: 60 (74%) of 81 MMB pts and 25 (58%) of 43 DAN pts with BL PLT ≤150 x 109/L completed the 24-week randomized treatment (RT) phase. Median BL TSS were 29 (MMB) and 24 (DAN), Hgb were 7.9 (MMB) and 8.0 (DAN) g/dL, and PLT were 67 x 109/L (MMB) and 64 x 109/L (DAN). Prior JAKi was ruxolitinib in 124 pts (100%) and fedratinib in 6 pts (5%). Efficacy results are in Table. These results are consistent with the overall ITT analysis set (N=195). Most common Gr ≥3 TEAEs in the RT phase were thrombocytopenia (MMB, 31%; DAN, 16%) and anemia (MMB, 7%; DAN, 14%); Gr ≥3 bleeding events occurred in 9% of MMB and 5% of DAN pts. TEAEs led to study drug discontinuation in 15% of MMB and 19% of DAN pts in RT phase. A trend toward improved OS up to wk 24 was seen with MMB vs DAN [HR (95% CI)=0.490 (0.195, 1.235)]. Additional analyses of pts with BL PLT 9/L (N=100) and BL PLT 9/L (N=31) show similar treatment effects of MMB vs DAN. Conclusions: In thrombocytopenic MF pts who were symptomatic and anemic, MMB was superior to DAN for symptom responses, transfusion requirements, and spleen responses and showed comparable safety and favorable survival. MMB may address a critical unmet need in thrombocytopenic MF pts. Clinical trial information: NCT04173494. [Table: see text]

7002 Background: MMB, an oral JAK1/2 and ACVR1/ALK2 inhibitor, showed clinical activity on MF symptoms, RBC transfusion requirements (anemia), and spleen volume in the SIMPLIFY trials. This pivotal phase 3 study of MF patients (pts) previously treated with a JAK inhibitor (JAKi) tested MMB vs DAN on key symptom, anemia, and spleen volume endpoints at 24 weeks (wks). Methods: Eligibility: Primary or post-ET/PV MF; DIPSS high risk, Int-2, or Int-1; MF Symptom Assessment Form Total Symptom Score (MFSAF TSS) ≥10; Hgb 9/L. BL TI was 13% (MMB) and 15% (DAN). Prior JAKi was ruxolitinib in 195 pts (100%) and fedratinib in 9 pts (5%). All primary and key secondary endpoints were met (Table). Most common Gr ≥3 TEAEs in the RT phase of the study were thrombocytopenia (MMB, 22%; DAN, 12%) and anemia (MMB, 8%; DAN, 11%). Gr ≥3 infections occurred in 15% of MMB and 17% of DAN pts. Peripheral neuropathy occurred in 5 (4%) of MMB (all Gr ≤2) and 1 (2%) of DAN (Gr ≤2) pts in the RT phase, and none discontinued study drug. Overall, TEAEs led to study drug discontinuation in 18% of MMB and 23% of DAN pts in RT phase. A trend toward improved OS up to wk 24 was seen with MMB vs DAN (HR=0.506, p=0.0719). Conclusions: In symptomatic and anemic MF pts, MMB was superior to DAN for symptom responses, transfusion requirements, and spleen responses with comparable safety and favorable survival. MMB may address a critical unmet need, particularly in MF pts with anemia. Clinical trial information: NCT04173494. [Table: see text]

Background A double-blind, placebo-controlled, phase III study (200622) showed that mepolizumab reduces disease flares for patients with uncontrolled FIP1-like-1-platelet-derived growth factor receptor α–negative hypereosinophilic syndrome (HES) and two or more flares in the previous year. Objective To further characterize the safety, clinical benefit, and pharmacodynamics of mepolizumab. Methods Eligible patients from both treatment arms of the double-blind study could enter an open-label extension study (205203; NCT03306043) to receive 4-weekly mepolizumab (300 mg subcutaneously) plus background therapy for 20 weeks. Primary end points were safety-based; other end points included flare rates and changes from baseline in mean daily oral corticosteroid (OCS) dose and blood eosinophil count. Results Of 104 patients who completed the double-blind study, 98% (previous placebo, n = 52; previous mepolizumab, n = 50) enrolled in the open-label extension. Overall, 66 of patients reported adverse events (AEs) (65%), 15 reported treatment-related AEs (15%), and nine reported serious AEs (9%). No events were fatal. The annualized flare rate (95% confidence interval) in the previous placebo and previous mepolizumab groups was 0.37 (0.16-0.86) and 0.14 (0.04-0.49) events/y, respectively. Of 72 patients receiving OCS during weeks 0 to 4, 20 (28%; previous placebo, n = 14; previous mepolizumab, n = 6) achieved 50% or greater reductions in mean daily dose during weeks 16 to 20. At week 20, blood eosinophil count was reduced by 89% in patients previously receiving placebo and remained reduced for those previously receiving mepolizumab. Conclusions Extended mepolizumab treatment was associated with a positive benefit–risk profile. Continued control of disease flares and blood eosinophil counts, plus reductions in OCS use, were observed with mepolizumab in patients with FIP1-like-1-platelet-derived growth factor receptor α–negative HES.

© The Author(s) 2021., This study reports on 382 COVID-19 patients having undergone allogeneic (n = 236) or autologous (n = 146) hematopoietic cell transplantation (HCT) reported to the European Society for Blood and Marrow Transplantation (EBMT) or to the Spanish Group of Hematopoietic Stem Cell Transplantation (GETH). The median age was 54.1 years (1.0–80.3) for allogeneic, and 60.6 years (7.7–81.6) for autologous HCT patients. The median time from HCT to COVID-19 was 15.8 months (0.2–292.7) in allogeneic and 24.6 months (−0.9 to 350.3) in autologous recipients. 83.5% developed lower respiratory tract disease and 22.5% were admitted to an ICU. Overall survival at 6 weeks from diagnosis was 77.9% and 72.1% in allogeneic and autologous recipients, respectively. Children had a survival of 93.4%. In multivariate analysis, older age (p = 0.02), need for ICU (p < 0.0001) and moderate/high immunodeficiency index (p = 0.04) increased the risk while better performance status (p = 0.001) decreased the risk for mortality. Other factors such as underlying diagnosis, time from HCT, GVHD, or ongoing immunosuppression did not significantly impact overall survival. We conclude that HCT patients are at high risk of developing LRTD, require admission to ICU, and have increased mortality in COVID-19., JA acknowledges the support of the UK NIHR Imperial College Biomedical Research Centre.

COVID-19 is a severe infectious complication in patients with underlying medical conditions such as having undergone hematopoietic stem cell transplantation (HCT). This prospective survey reports outcome on 272 COVID-19 patients from 19 countries having undergone allogeneic (n = 175) or autologous (n = 97) HCT reported to the EBMT registry or to the GETH. All patients had the diagnosis of SARS-CoV-2 documented by PCR. Patients were included in this analysis if COVID-19 diagnosis was before April 10, 2020. The overall survival was estimate by using the Kaplan Meier methods, considering the death due to any cause as an event and the time from COVID-19 infection to the latest follow-up as survival time; difference between groups were tested by the log-rank test. Univariate and multivariate risk factor analysis for overall survival were performed with the Cox regression model. The median age was 54.4 years (1.0 - 80.3) for allogeneic and 60.9 years (7.7 - 73.4) for autologous HCT patients. 20 patients were children (< 18 years of age; median age 11.3 (1.0 - 16.9)). The median time from HCT to diagnosis of COVID-19 was 13.7 months (0.2 - 254.3) in allogeneic and 25.0 months (-0.9 - 350.3) in autologous recipients. Lower respiratory tract disease (LRTD) developed in 84.8% and 21.5% were admitted to an intensive care unit (ICU). At the time of analysis, 68/238 (28.6%) patients had died (47/155 allogeneic patients; 21/83 autologous patients). No follow-up had been received on 34 patients. The median time from infection to death was 19 days (0-102). Five patients were reported to have other primary causes of death than COVID-19. Of the patients reported to be alive, the median follow-up was 44 days. 144 (84.7%) patients (93 allogeneic; 51 autologous) had virologic resolution of the COVID-19 infection having at least one negative PCR. 26 patients were alive and known to be still COVID-19 positive (15 allogeneic; 11 autologous). For 34 patients the resolution status was unknown. Factors influencing the likelihood of resolution in multivariate analysis were underlying diagnosis (p=.01) and longer time from transplant to diagnosis of COVID-19 (p=.035). Overall survival at 6 weeks from COVID-19 diagnosis was 76.8% and 83.8% in allogeneic and autologous HCT recipients (p =ns), respectively (figure 1). Children (n=20) tended to do better with a 6-week survival of 95.0% although the difference was not significantly different (p =.12). In multivariate analysis of the total population older age (HR 1.26; 95% CI 1.05 - 1.51; p = .01) increased the risk and better performance status decreased the risk for fatal outcome (HR 0.79; 95% CI 0.69 - 0.90; p = .0003). The same factors had significant impact on overall survival in allogeneic HCT recipients (age HR 1.28; 95% CI 1.05 - 1.55; p=.01; performance status HR 0.79; 95% CI 0.68 - 0.92); p=.002) while only age impacted survival among autologous HCT patients (data not shown). Other transplant factors such as underlying diagnosis, time from HCT to diagnosis of COVID-19, graft-vs-host disease, or ongoing immunosuppression did not have a significant impact on overall survival. We conclude that HCT patients are at an increased risk compared to the general population to develop LRTD, require admission to ICU, and have increased mortality in COVID-19. Figure 1 Disclosures Duarte: Incyte Corporation: Other: Has received speaker and advisor fees. Kwon:Jazz: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria. Mielke:Novartis: Honoraria, Other: received via my institution, Speakers Bureau; Celgene/BMS: Honoraria, Other: received via my institution , Speakers Bureau; Bellicum: Honoraria, Other: received via my institution, Speakers Bureau; Kite/Gilead: Honoraria, Other: received via my institution , Speakers Bureau; Miltenyi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: received via my institution , Speakers Bureau; KIADIS Pharma: Honoraria, Other: received via my institution , Speakers Bureau; DNA Prime: Honoraria, Other: received via my institution , Speakers Bureau. López Jiménez:MSD: Speakers Bureau; Roche: Research Funding, Speakers Bureau; Takeda: Speakers Bureau; Janssen: Research Funding, Speakers Bureau; Abbvie: Research Funding, Speakers Bureau; Gilead: Research Funding, Speakers Bureau.

OBJECTIVES: In patients with essential thrombocythemia (ET), after the JAK2V617F driver mutation, mutations in CALR are common (classified as type-1, 52-bp deletion, or type-2, 5-bp insertion). CALR mutations have generally been associated with a lower risk of thrombosis. This study aimed to confirm the impact of CALR mutation type on thrombotic risk. METHODS: We retrospectively investigated 983 ET patients diagnosed in Spanish and Polish hospitals. RESULTS: With 7.5 years median follow-up from diagnosis, 155 patients (15.8%) had one or more thrombotic event. The 5-year thrombosis free survival (TFS) rate was 83.8%, 91.6% and 93.9% for the JAK2V617F, CALR-type 1 and CALR-type 2 groups, respectively (p = 0.002). Comparing CALR-type 1 and CALR-type 2 groups, TFS for venous thrombosis was lower in CALR-type 1 (p = 0.046), with no difference in TFS for arterial thrombosis observed. The cumulative incidence of thrombosis was significantly different comparing JAK2V617F vs. CALR-type 2 groups but not JAK2V617F vs. CALR-type 1 groups. Moreover, CALR-type 2 mutation was a statistically significant protective factor for thrombosis with respect to JAK2V617F in multivariate logistic regression (OR: 0.45, p = 0.04) adjusted by age. CONCLUSIONS: Our results suggest that CALR mutation type has prognostic value for the stratification of thrombotic risk in ET patients.

Allogeneic hematopoietic cell transplantation (allo-HCT) remains the only curative option in MF. There is no consensus on the optimal conditioning regimen. We report outcomes of 187 patients with MF transplanted between 2010 and 2017 conditioned with TBF. Median age was 58 years. Median interval from diagnosis to allo-HCT was 44 months. Donors were haploidentical (41%), unrelated (36%) or HLA-identical siblings (23%). Stem cell source was PB in 60%. Conditioning was myeloablative in 48% of cases. Antithymocyte globulin (ATG) was used in 41% of patients. At 100 days, neutrophil and platelet engraftment were 91% and 63% after a median of 21 and 34 days, respectively. Grade II-IV and III-IV acute GVHD occurred in 24% and 12%, while at 3 years, all grade chronic GVHD and chronic extensive GVHD had been diagnosed in 38% and 11%. At 3 years, OS, RFS and GRFS were 55%, 49% and 43%, respectively. RI and NRM were 17% and 33%. On multivariate analysis, poor KPS and the use of unrelated donors were associated with worse GRFS and a higher grade II-IV acute GVHD, respectively. Neither donor type nor intensity of the conditioning regimen influenced survival outcomes. TBF is a feasible conditioning regimen in allo-HCT for MF in all donor settings although longer term outcomes are required.

In classical reduced-intensity conditioning (RIC) regimens, including the fludarabine and busulphan (BF) combination, sirolimus and tacrolimus (SIR-TAC) as graft vs host disease (GVHD) prophylaxis has shown acceptable results. The outcomes of SIR-TAC in a more intense RIC regimen as Thiotepa-fludarabine-busulfan (TBF) have been hardly investigated. This retrospective study included all consecutive patients receiving an allogeneic hematopoietic stem cell transplantation for myeloid malignancies (January 2009-2017) conditioned with either TBF or BF and receiving SIR-TAC. Patients receiving TBF presented higher non-relapse mortality (31.6 vs 12.3%,p = .01), along with shorter overall survival (51.8% vs 77.8%,p < .01) at 2 years than patients treated with BF. There were no significant differences in the cumulative incidence of grade II-IV acute GVHD or moderate-severe chronic GVHD or relapse between both groups. These results suggest that TBF does not seem to improve the traditional RIC BF regimen, at least when associated with SIR-TAC prophylaxis.

Introduction Malignancy can be heralded by unprovoked venous thromboembolism (VTE) but also by arterial thrombosis. To date it is unknown whether this association is present also in myeloproliferative neoplasms (MPN), in which arterial thrombosis is more frequent that venous thrombosis and solid tumors are reported with an increased frequency. The MPN-K nested case-control study addressed the impact of cytoreductive drugs on the risk of developing second cancer in MPN patients (Barbui T et al, Leukemia 2019); here we re-examined the study database to evaluate the frequency and type of vascular complications in MPN patients with second cancer excluding leukemia and to establish whether arterial and venous thrombosis during follow-up after diagnosis of MPN could predict the occurrence of a second cancer. Patients and methods Cases were patients with second cancer diagnosed concurrently or subsequent to the diagnosis of MPN. Controls were MPN patients without second cancer. For each case with second cancer, up to 3 cancer-free controls were matched by each center for sex, age at MPN diagnosis, date of MPN diagnosis, and MPN disease duration. Each set consisting of one case and their matched-controls had a similar observational period (from MPN diagnosis until the index date of diagnosis for the second cancer). The study included 647 cases with second cancer (carcinoma, non-melanoma-skin cancers, hematological secondary cancer and melanoma). The most frequent category was carcinoma (n=426, 65.8%). Cases were comparable with the 1,234 matched controls for demographics, type of MPN, and exposure to potential confounders such as mutational profile, abnormal karyotype and cardiovascular risk factors. The thrombotic events of interest were ischemic stroke, transient ischemic attacks, acute coronary syndromes, peripheral arterial thrombosis, deep venous thrombosis (including thrombosis of cerebral and splanchnic veins) and pulmonary embolism. Thrombosis had to be concurrent with or in the 2 years before MPN diagnosis or occurring after MPN diagnosis. The cumulative incidence of either arterial or venous thrombosis from MPN diagnosis was estimated by the Kaplan-Meier method and was compared between cases and controls using the log-rank test. A conditional logistic regression model estimated the Odds Ratio (OR) with 95% Confidence Interval (CI) of second cancer associated with the occurrence of thrombosis before/at diagnosis of MPN and during follow-up. Other covariates were patient age, cardiovascular risk factors, the JAK2V617F mutation, and treatment during follow-up. Results Approximately 20% of either MPN cases or controls had thrombosis before MPN or at diagnosis (19.8% vs. 21.1%, respectively, p=0.462). After a median observation time from diagnosis of MPN to an index date of 4.5 years (interquartile range 1.5-8.2) in cases and 3.7 years (interquartile range 1.5-7.5) in controls, cases showed a percentage of thrombosis higher than in controls (75/647, 11.6% vs. 100/1234, 8.1%, respectively, p=0.013). Approximately one-third of thrombosis preceding cancer occurred in the 12 months before the diagnosis of second cancer (22/75, 29.3%). The excess of thrombosis in cases was due to a higher frequency of arterial thrombosis (6.2% vs. 3.7%, p=0.015), whereas no significant difference was found for venous thrombosis (5.4% vs. 4.3%, p=0.277). While the cumulative incidence of venous thrombosis over time was similar among cases and controls (p=0.864), the cumulative incidence of arterial thrombosis was higher in cases with second cancer (p=0.006) (Figure 1). The excess of arterial thrombosis after MPN diagnosis was limited to cases with carcinoma (6.8% vs 3.9%, p=0.027). In a multivariable model, arterial thrombosis during the follow-up was confirmed to be an independent predictor factor for carcinoma, with an odds ratio of 1.97 (95%CI 1.14-3.41, p=0.015). Conclusions. These findings reveal an association of arterial thrombosis with subsequent second cancer (namely carcinoma) in MPN patients. A possible biological plausibility for this link may be related to an underlying common pathogenic mechanism such as an aberrant inflammatory response consistently found in MPN. This observation may have practical implications and suggests careful clinical surveillance for early diagnosis of second cancer in MPN patients with arterial thrombosis during the follow-up. Disclosures Palandri: Novartis: Consultancy, Honoraria. Iurlo:Novartis: Other: Speaker Honoraria; Incyte: Other: Speaker Honoraria; Pfizer: Other: Speaker Honoraria. Bonifacio:Incyte: Honoraria; Novartis: Honoraria; Amgen: Honoraria; Pfizer: Honoraria; BMS: Honoraria. Rumi:novartis: Honoraria, Research Funding. Elli:Novartis: Membership on an entity's Board of Directors or advisory committees. Lunghi:Pfizer: Honoraria; Novartis: Honoraria; Incyte: Honoraria. Benevolo:Novartis Pharmaceuticals: Consultancy. McMullin:Italopharma: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Speakers Bureau; Daiko Sanyo: Membership on an entity's Board of Directors or advisory committees. Griesshammer:Novartis: Consultancy, Honoraria, Speakers Bureau. Vannucchi:CTI: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees; Italfarmaco: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees. Rambaldi:Pfizer: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau.

We conducted a large international nested case-control study including 1881 patients with Philadelphia-negative myeloproliferative neoplasms (MPN). Cases (n = 647) were patients with second cancer (SC: carcinoma, non-melanoma skin cancer, hematological second cancer, and melanoma) and controls (n = 1234) were patients without SC, matched with cases for sex, age at MPN diagnosis, date of MPN diagnosis, and MPN disease duration. The aim was to evaluate the risk of SC after exposure to cytoreductive drugs. Patients exposed to hydroxyurea (HU) (median: 3 years) had a risk of SC similar to unexposed patients (OR = 1.06, 95% CI 0.82-1.38). In contrast, in cancer-specific stratified multivariable analysis, HU had two-fold higher risk of non-melanoma (NM) skin cancer (OR = 2.28, 95% CI 1.15-4.51). A significantly higher risk of NM-skin cancer was also documented for pipobroman (OR = 3.74, 95% CI 1.00-14.01), ruxolitinib (OR = 3.87, 95% CI 1.18-12.75), and for drug combination (OR = 3.47, 95% CI 1.55-7.75). These three drugs did not show excess risk of carcinoma and hematological second cancer compared with unexposed patients. Exposure to interferon, busulfan, and anagrelide did not increase the risk. In summary, while it is reassuring that no excess of carcinoma was documented, a careful dermatologic active surveillance before and during the course of treatments is recommended.

e19040 Background: Clinical trials investigating JAK1/JAK2 inhibitors for myelofibrosis (MF) subjects have measured symptom improvement as a minimum 50% reduction in total symptom score (TSS) at the end of a 24-week treatment period. This landmark analysis is based on post-baseline score changes from Weeks 21 (W21) to 24 and requires vastly different absolute TSS improvements for patients with very high or low baseline (BL) TSS to reach responder status. A phase 3 clinical study, SIMPLIFY-1, randomized 432 intermediate and high risk JAK inhibitor (JAKi) naive MF patients 1:1 to momelotinib (MMB) or ruxolitinib (RUX). Non-inferiority on the MPN-SAF TSS response rate endpoint at W24 was not met (MMB: 28% vs RUX: 42%); however, improvement in each of the 7 TSS items was similar for MMB vs RUX. To understand the discrepancy, we applied item analysis and mixed effect models for repeated measures (MMRM) to SIMPLIFY-1. Methods: Analyses were conducted in the intention-to-treat (ITT) population and in a symptomatic subset (selected as subjects with BL TSS ≥ 10). The distributions of TSS items were examined at BL and shift in scores at W24 (health state shifts) were assessed. GEE models were used to estimate item-level odds ratios using multiple predictive imputations for missing data. MMRM compared mean change in TSS from BL to W24 using data from all visits. The meaningful change threshold (MCT) was determined using Patient Global Impression of Change. Results: BL scores across items were heterogenous in the MMB and RUX groups; the proportion of subjects with no or mild symptoms (0–3 on a 0-10 point scale) ranged from 44% (tiredness) to 81% (itching). Distributions of BL scores were different across arms with 6 out of 7 items in the MMB arm reporting more severe or very severe symptoms (scores of 7-10) at BL. Despite the imbalance in BL scores, item-level health state shifts showed similar improvements for MMB and RUX. Categorical responder analysis showed no significant differences on any items. Odds ratios for each between-group comparison ranged from 0.74 to 1.20. MMRM mean TSS change at W24 was 6.35 (MMB) vs 7.87 (RUX) in the ITT and 8.80 (MMB) vs 10.46 (RUX) in the symptomatic subset. Mean TSS were near the within-subject MCT of 8 points in the ITT and exceeded the MCT in the symptomatic subset. The between-group difference was 1.52 (95% CI: (0.196, 2.847)) in the ITT and 1.67 (95% CI: -0.134, 3.468) in the symptomatic subset. Conclusions: Comparable item health state shifts at W24 and similar improvements in mean TSS as shown by MMRM, with a minimal between-group difference of 1.52 on the 70 point scale in context of an 8-point MCT suggest MMB provides clinically relevant and comparable symptom improvements to RUX; these analyses require further validation in independent data sets. Imbalance in BL symptom scores in MMB subjects may have contributed to the inability to demonstrate non-inferiority in TSS response rate at W24. Clinical trial information: NCT01969838.

Reduced-intensity conditioning (RIC) and T cell depletion (TCD) through CD34+ cell selection without the use of post-transplantation immunosuppression are 2 strategies used to reduce nonrelapse mortality (NRM) in older patients after allogeneic hematopoietic cell transplantation (allo-HCT). To compare the efficacy of the RIC and TCD approaches, we evaluated the outcomes of patients age >50 years with acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS) who underwent allo-HCT from an HLA-matched donor with one of these strategies. Baseline characteristics were comparable in the patients receiving TCD (n = 204) and those receiving RIC (n = 151), except for a higher proportion of unrelated donors (68% versus 40%; P 50 years with acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS) who underwent allo-HCT from an HLA-matched donor with one of these strategies. Baseline characteristics were comparable in the patients receiving TCD (n = 204) and those receiving RIC (n = 151), except for a higher proportion of unrelated donors (68% versus 40%; P 50 years with AML and MDS.

There is a paucity of data evaluating acute kidney injury (AKI) incidence and its relationship with the tacrolimus-sirolimus (Tac-Sir) concentrations in the setting of reduced-intensity conditioning (RIC) after allogeneic stem cell transplantation (allo-HSCT). This multicenter retrospective study evaluated risk factors of AKI defined by 2 classification systems, Kidney Disease Improving Global Outcome (KDIGO) score and "Grade 0-3 staging," in 186 consecutive RIC allo-HSCT recipients with Tac-Sir as graft-versus-host disease prophylaxis. Conditioning regimens consisted of fludarabine and busulfan (n = 53); melphalan (n = 83); or a combination of thiotepa, fludarabine, and busulfan (n = 50). A parametric model, with detailed Tac-Sir consecutive blood levels, describing time to AKI was developed using the NONMEM software version 7.4. Overall, 81 of 186 (44%) RIC allo-HSCT recipients developed AKI with a cumulative incidence of 42% at a median follow-up of 25 months. Time to AKI was best described using a piecewise function. AKI-predicting factors were melphalan-based conditioning regimen (HR, 1.96; P < .01), unrelated donor (HR, 1.79; P = .04), and tacrolimus concentration: The risk of AKI increased 2.3% per each 1-ng/mL increase in tacrolimus whole blood concentration (P < .01). In multivariate analysis, AKI grades 2 and 3 according to KDIGO staging were independent risk factors for 2-year nonrelapse mortality (HR, 2.8; P = .05; and HR, 6.6; P < .0001, respectively). According to the KDIGO score, overall survival decreased with the increase in severity of AKI: 78% for patients without AKI versus 68%, 50%, and 30% for grades 1, 2, and 3, respectively (P < .0001). In conclusion, AKI is frequent after Tac-Sir-based RIC allo-HSCT and has a negative impact on outcome. This study presents the first predictive model describing time to AKI as a function of tacrolimus drug concentration. (C) 2017 American Society for Blood and Marrow Transplantation.

Hematocrit control below 45% is associated with a lower rate of thrombosis in polycythemia vera. In patients receiving hydroxyurea, this target can be achieved with hydroxyurea alone or with the combination of hydroxyurea plus phlebotomies. However, the clinical implications of phlebotomy requirement under hydroxyurea therapy are unknown. The aim of this study was to evaluate the need for additional phlebotomies during the first five years of hydroxyurea therapy in 533 patients with polycythemia vera. Patients requiring 3 or more phlebotomies per year (n=85, 16%) showed a worse hematocrit control than those requiring 2 or less phlebotomies per year (n=448, 84%). There were no significant differences between the two study groups regarding leukocyte and platelet counts. Patients requiring 3 or more phlebotomies per year received significantly higher doses of hydroxyurea than the remaining patients. A significant higher rate of thrombosis was found in patients treated with hydroxyurea plus 3 or more phlebotomies per year compared to hydroxyurea with 0-2 phlebotomies per year (20.5% vs. 5.3% at 3 years; P

Introduction: Allogeneic hematopoietic cell transplantation (allo-HCT) constitutes the only curative treatment for myelofibrosis (MF), but its associated toxicity remains high. Prognostic risk models are widely used in clinical practice to select those MF patients who are more likely to benefit from transplantation. Recently, a new prognostic model, the Myelofibrosis Transplant Scoring System (MTSS), has been developed to predict the outcome of MF patients undergoing allo-HCT (Gagelmann N et al, Blood 2019). We aimed to evaluate the performance of such model in an independent series of patients. Methods: This is a retrospective study that included all adult patients who underwent first allo-HCT for MF between January 2005 and May 2019 in 8 Spanish hospitals. Patients transplanted after leukemic transformation were excluded. Survival probability from the time of HCT was estimated by the method of Kaplan-Meier and compared by the log-rank test. Each parameter of the MTSS was tested for its potential association with survival in univariate analysis. Cumulative incidence functions were used to estimate incidence of Graft-versus-Host-Disease (GVHD), Relapse Incidence (RI), and Non-Relapse Mortality (NRM) within a competing risk setting. Statistical analyses were performed with SPSS 19 (SPSS Inc./IBM, Armonk, NY) and R. Results: Demographics and transplant characteristics of the overall series of 107 MF patients are shown in Table 1. After a median follow-up from allo-HCT of 5.3 years, 49 patients (46%) had died. The survival probability at 1, 3, and 5-years was 64.5%, 52%, and 50%, respectively. Transplantation outcome improved over the years. Thus, the survival probability at 3-years was 35% (95% CI: 12-58), 50% (95% CI: 33-67), and 65% (95% CI: 50-80) during the time periods 2005-2009 (n=17), 2010-2014 (n=34), and 2015-2019 (n=56), respectively (P=0.038). The cumulative incidence of grade II-IV acute GVHD at day 100 was 45%. The cumulative incidence of relapse at 1, 3, and 5-years was 16%, 19.5%, and 19.5%, respectively. NRM probability at 1, 3, and 5-years was 24%, 29%, and 31%, respectively. In univariate analysis, the only parameter included in the MTSS that was significantly associated with survival was the Karnofsky performance status < 90% (HR: 1.9, 95% CI: 1.1-3.4; P=0.031). Neither age > 57 years (P=0.68), platelets 25 x 109/L (P=0.38), ASXL1 mutations (P=0.34), non-CALR/MPL driver mutation (P=0.57) nor HLA-mismatched unrelated donor (P=0.22) correlated with survival. Among other classical risk factors for transplant outcome, only a comorbidity index >= 3 was significantly associated with shorter survival (HR: 2.1, 95% CI: 1.1-4; P=0.017). A total of 64 cases had all required clinical and molecular data to calculate the MTSS. Figure 1 shows the survival curves of the different risk groups as defined by the MTSS. As can be seen, the prognostic model was not able to discriminate four risk groups. We then pooled together patients assigned to the low (n=26) and intermediate risk (n=23) groups, and those within the high (n=9) and very high risk (n=6) groups. On this basis, two-categories could be identified: standard risk (n=49 [77% of patients]) and high risk (n=15 [23%]). The 3-year overall survival was 65% (95% CI: 51-79) in the standard risk and 17% (95% CI: 0-46) in the high risk categories (P=0.060)(Figure 2). Conclusions: the MTSS did not discriminate four different risk categories in our series. Both, the limited number of cases and the differences in patients and transplant characteristics in our series as compared to those of the original MTSS cohort might account for this finding. Nevertheless, the MTSS was able to identify a subset of patients with a very poor prognosis after transplantation. Such information could be useful to assist on transplant decision-making. Disclosures Sanchez-Guijo: Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Amgen: Honoraria; Roche: Honoraria. Hernandez Boluda:Incyte: Other: Travel expenses paid.

Introduction The clinical characteristics, treatment, cardiovascular events (CVE) and evolution of patients diagnosed with JAK2 V617F positive essential thrombocythemia (ET) with low allele burden (LAB) are scarcely studied. Its presence in people without a confirmed diagnosis of malignant hemopathy is called clonal hematopoiesis of uncertain significance (CHIP) and confers higher risk of developing CVE. The objective of this study was to compare the clinical characteristics and CVE of a series of JAK2 V617F-positive ET patients with Methods From the database of the GEMFIN group, 410 ET patients were JAK2 V617F positive, 89 (21.7 %) with LAB and 321 (78.3%) with HAB. The clinical characteristics, treatment (cytoreduction, antiagregation, anticoagulation, JAK inhibitor), CVE (before, at and after diagnosis) and evolution to myelofibrosis (MF) or acute myeloid leukemia (AML) of these two groups of patients were compared. Results LAB and HAB groups did not significantly differ regarding the main clinical characteristics (i.e cardiovascular risk factors [CVRF] and International Prognostic Score for Thrombosis in Essential Thrombocythemia [IPSET] score) except for the median platelet count: LAB 636 x109/L [436- 2500] vs HAB 687 x109/L[440-1980L], p=0.035). CVE after diagnosis of ET were more frequent in patients with HAB (41/137, 30%) than in patients with LAB (5/48, 10%), p=0.007. Only one LAB patient with CVE had JAK2 allele burden >5%. Treatments received by both groups were not significantly different. None of the patients from both groups progressed to AML, whereas 1/48 vs. 6/137 of patients evolved to MF. Median follow-up of patients with LAB and HAB was 3.4 years [0.1-17.7] and 4.3 years [0.1-27.8], respectively (Table 1). Conclusions In these series of ET patients from the GEMFIN group, patients with LAB had significantly lower median platelet count at diagnosis and less CVE after diagnosis than patients with HAB, although CVRF and IPSET scores and treatment approach were similar. The clinical behavior of LAB patients may resemble that of individuals with CHIP. The therapeutic algorithm of ET patients with LAB may be somehow different than that of patients with HAB and therefore, might be revised. Disclosures Bellosillo: Astra-Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Biocartis: Honoraria; Merck-Serono: 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; Qiagen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Hoffman â€"La Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; ThermoFisher: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria; BMS: Honoraria. Hernandez Boluda:Incyte: Other: Travel expenses paid. Pérez:Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

INTRODUCTION The incidence of secondary cancer (SC) in patients with myeloproliferative neoplasms (MPN) is high and comparable to that of thrombosis. However, the identification of patient subgroups that might be at increased susceptibility of developing SC has not been systematically addressed. We report here the results of an international case-control study (MPN-K) aimed at comparing the frequency of exposure to possible causes of SC in patients with classical MPN, polycythemia vera (PV), essential thrombocythemia (ET) and myelofibrosis (MF). METHODS This European Leukaemia Network (ELN) study reports MPN patients from 28 sites of 5 European countries and Israel, diagnosed in the period from 2000 to 2016. Cases were MPN patients with concomitant diagnosis of a non-myeloid SC (n=15) or its presentation during the course of the disease (n=412). Controls were MPN patients cancer-free, matched to the paired case for sex, age (±5 years), date of MPN diagnosis (±5 years), and MPN disease duration (±6 years). A multivariable conditional logistic regression model was used to estimate the effect of selected variables on total SC risk and in different types of SC. RESULTS Among 1,259 MPN patients, there were 427 cases and 832 matched controls. Cases presented melanoma (n=20; 4.7%), non-melanoma skin cancer (n=69; 16.2% - basal/squamous cell carcinoma), non-skin solid cancer (n=290; 67.9%) including breast, ovary/uterus, colorectal, upper gastrointestinal, liver/pancreas, lung, prostate/urinary, other and lymphoproliferative diseases (n=48; 11.2%) including multiple myeloma, chronic lymphocytic leukemia, low and high grade B- and T-lymphoma. At diagnosis, there were slightly more patients with PV among SC cases (n= 152; 35.6%) than controls (n=256; 30.8%), while conversely there were slightly less ET patients among cases (n=196; 45.9%) than controls (n=426; 51.2%). Cases and controls presented similar proportion of MF diagnosis (n=79 cases, 18.5% and 150 controls, 18.0%). Driver mutations (JAK2 V617, EXON-12, CALR, MPL), non-driver mutations and abnormal karyotype were equally represented in cases and controls. Other variables such as cardiovascular risk factors, exposure to cancerogens, family history of cancer and chronic inflammatory diseases were reported with similar frequency in cases and controls. After MPN diagnosis, exposure to first and other lines of treatments until the index event, with Phlebotomy (n=193; 15.3%), Hydroxyurea (n=814; 64.7%), Anagrelide (n=14; 1.1%), Interferon (n=30; 2.4%), Pipobroman (n=8; 0.6%), Busulphan (n=13; 1.0%), Ruxolitinib (n=11; 0.9%), was similar in the two groups except for aspirin that was used less frequently (p=0.043) in cases (n=320; 74.9%) compared to controls (n=664; 79.9%). In particular, the lower use of aspirin was circumscribed to non-skin solid tumors. A multivariable analysis was carried out in all patients and stratified by different type of tumors (Table). In non-skin solid cancers, the time to exposure of the MPN disease > 5 years (OR=2.95; 95% CI 1.54-5.66, p=0.001) and the PV phenotype (OR=2.40, 95% CI 1.15-5.01, p=0.020) were more burdened by the incidence of events than the reference ET group. No difference in SC risk was found for MF patients compared to patients with ET. Interestingly, the independent protective role of aspirin retained its statistical significance only in non-skin SC. In non-melanoma skin cancer, multivariable analysis revealed that the presence of JAK2 mutation was less associated with SC (OR=0.32, 95% CI 0.13-0.81, p=0.016) and confirmed that exposure to HU and other cytotoxic agents was associated with a significantly higher risk of SC (OR=6.00, 95% CI 1.23-29.28, p=0.027 and OR=9.80, 95% CI 1.24-77.78, p=0.031, respectively). This finding was not seen in non-skin SC and in lymphoma. CONCLUSION The considered clinical and biological features, at MPN diagnosis, were not different in cases with SC and controls. During the course of the disease, three factors significantly and independently affected the risk of SC in these MPN patients: 1) patients with PV had a 77% higher risk than those with ET, 2) patients with MPN duration of more than 5 years had a twice higher risk than those with lower duration, 3) for the first time, we documented that in non-skin solid cancers, aspirin treatment reduced SC risk of 38%. Exposure to HU and other cytoreductive drugs was confirmed as a risk factor for non-melanoma skin cancer. Disclosures Palandri: Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Marchetti:Gilead: Consultancy; takeda: Speakers Bureau; amgen: Speakers Bureau; janssen: Speakers Bureau. Griesshammer:Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.