The Medalist Trial: Results of a Phase 3, Randomized, Double-Blind, Placebo-Controlled Study of Luspatercept to Treat Anemia in Patients with Very Low-, Low-, or Intermediate-Risk Myelodysplastic Syndromes (MDS) with Ring Sideroblasts (RS) Who Require Red Blood Cell (RBC) Transfusions

Abstract Introduction: MDS is associated with an erythroid maturation defect, characterized by ineffective erythropoiesis leading to anemia and RBC transfusion dependence. Treatment of anemia in lower-risk MDS remains an unmet medical need. Luspatercept is a first-in-class erythroid maturation agent which binds to select TGFβ superfamily ligands to reduce aberrant Smad2/3 signaling and enhance late-stage erythropoiesis (Suragani RN, et al. Nat Med. 2014;20:408-14). Preliminary clinical studies have shown promising activity in MDS (Platzbecker U, et al. Lancet Oncol. 2017;10:1338-47). We report the results of a phase 3, randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of luspatercept in patients with anemia due to Revised International Prognostic Scoring System (IPSS-R)-defined Very low-, Low-, or Intermediate-risk MDS with RS who require RBC transfusions. ClinicalTrials.gov identifier: NCT02631070. Methods: Eligible patients were aged ≥ 18 years; had IPSS-R-defined Very low-, Low-, or Intermediate-risk MDS with RS according to the WHO 2016 criteria; were refractory, intolerant, or ineligible to receive erythropoiesis-stimulating agents (ESAs); and required RBC transfusions. Patients were randomized 2:1 to receive either luspatercept, at a starting dose level of 1.0 mg/kg with titration up to 1.75 mg/kg, if needed, or placebo, subcutaneously every 3 weeks for ≥ 24 weeks. The primary endpoint was RBC transfusion independence (RBC-TI) for ≥ 8 weeks between week 1 and week 24. A key secondary endpoint was RBC-TI for ≥ 12 weeks between week 1 and 24. Achievement of modified hematologic improvement-erythroid (mHI-E) response using IWG 2006 criteria was also assessed. Results: † A total of 229 patients were randomized and treated. Median age was 71 years (range 26-95), median time from diagnosis was 41.8 months (range 3-421), and 62.9% were male. Overall, patient baseline characteristics were balanced between the treatment groups. Patients received a median of 5 RBC units (range 1-20) transfused over 8 weeks during the 16 weeks prior to treatment (43.2% of patients had ≥ 6 RBC units/8 weeks, 27.9% had ≥ 4 to < 6 RBC units/8 weeks, and 28.8% had < 4 RBC units/8 weeks). At baseline, 138 (60.3%), 58 (25.3%), and 32 (14.0%) patients had serum erythropoietin levels < 200 IU/L, 200-500 IU/L, and > 500 IU/L, respectively. A total of 218 (95.2%) patients had previously received ESAs. Overall, 206 (90.0%) patients had an SF3B1 mutation. Of 153 patients receiving luspatercept, 58 (37.9%) achieved the primary endpoint of RBC-TI for ≥ 8 weeks compared with 10 of 76 patients (13.2%) receiving placebo (odds ratio [OR] 5.1, P < 0.0001). Of those receiving luspatercept, 43 of 153 (28.1%) achieved the key secondary endpoint of RBC-TI for ≥ 12 weeks (weeks 1-24) compared with 6 of 76 (7.9%) receiving placebo (OR 5.1, P = 0.0002). Patients receiving luspatercept were more likely to achieve an mHI-E response, defined as a reduction in transfusion of ≥ 4 RBC units/8 weeks or a mean hemoglobin increase of ≥ 1.5 g/dL/8 weeks in the absence of transfusions, compared with patients receiving placebo (52.9% vs 11.8% during weeks 1-24; P < 0.0001). The safety profile of luspatercept was consistent with that reported in the phase 2 PACE-MDS study (Platzbecker U, et al. Lancet Oncol. 2017;10:1338-47). Conclusions: Treatment with luspatercept resulted in a significantly reduced transfusion burden compared with placebo in patients with anemia due to IPSS-R-defined Very low-, Low-, or Intermediate-risk MDS with RS, who require RBC transfusions, and was generally well tolerated. P.F. and U.P. contributed equally to this abstract as lead co-authors. R.S.K. and A.F.L. contributed equally to this abstract as senior co-authors. † As of May 8, 2018, cutoff date. Disclosures Fenaux: Otsuka: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Platzbecker:Celgene: Research Funding. Mufti:Celgene: Research Funding. Buckstein:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Santini:Otsuka: Consultancy; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Research Funding; Novartis: Honoraria; AbbVie: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Díez-Campelo:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Finelli:Novartis: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Celgene: Research Funding, Speakers Bureau. Ilhan:Alexion: Speakers Bureau; BMS: Speakers Bureau; Roche: Speakers Bureau; Celgene: Speakers Bureau. Sekeres:Opsona: Membership on an entity's Board of Directors or advisory committees; Opsona: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Falantes:Celgene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Giai:Novartis: Consultancy; Pfizer: Consultancy. Selleslag:Kiadis Pharma: Other: Financial support for study-related issues. Jurcic:Actinium Pharmaceuticals, Inc: Research Funding; Daiichi-Sankyo: Research Funding; Astellas: Research Funding; Incyte: Consultancy; AbbVie: Consultancy, Research Funding; Kura Oncology: Research Funding; Genetech: Research Funding; Celgene: Research Funding; Forma Therapeutics: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Syros Pharmaceuticals: Research Funding. Germing:Novartis: Honoraria, Research Funding; Janssen: Honoraria; Celgene: Honoraria, Research Funding. Götze:Takeda: Honoraria, Other: Travel aid ASH 2017; Celgene: Honoraria, Research Funding; Novartis: Honoraria; JAZZ Pharmaceuticals: Honoraria. Quesnel:Celyad: Honoraria; Novartis: Honoraria; Astellas: Honoraria; Sunesis: Honoraria. Beyne-Rauzy:Novartis: Research Funding. Cluzeau:Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Menarini: Consultancy; Pfizer: Speakers Bureau. Voso:Celgene: Research Funding, Speakers Bureau. Zeidan:Otsuka: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Takeda: Honoraria, Speakers Bureau; Agios: Consultancy, Honoraria. Laadem:Celgene: Employment, Equity Ownership. Benzohra:Celgene: Employment, Equity Ownership. Zhang:Celgene: Employment, Equity Ownership. Rampersad:Celgene: Employment, Equity Ownership. Linde:AbbVie: Equity Ownership; Abbott Laboratories: Equity Ownership; Fibrogen: Equity Ownership; Acceleron Pharma: Employment, Equity Ownership. Sherman:Acceleron Pharma: Employment, Equity Ownership. Komrokji:Novartis: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Celgene: Honoraria, Research Funding; Novartis: Honoraria, Speakers Bureau; Celgene: Honoraria, Research Funding. List:Celgene: Research Funding.