Tara L. Chen, Megan Othus, Kaysey F. Orlowski, Heather A. Smith, Emily M Huebner, Paul C. Hendrie, Mary-Elizabeth M. Percival, Andrea M. Perdue, Roland B. Walter, Harry P. Erba, Anna B. Halpern, Bart L. Scott, Elihu H. Estey, Sarah A. Buckley, and Pamela S. Becker
Introduction:"7+3" with standard doses of cytarabine and an anthracycline has remained the mainstay of induction chemotherapy for newly diagnosed AML. Since some studies have shown improved outcomes with high-dose cytarabine, cladribine, or escalated doses of anthracyclines, we conducted a phase 1/2 study (NCT02044796) of G-CLAM using escalated doses of mitoxantrone for newly diagnosed AML or high-risk MDS (>10% blasts). Methods: Patients≥18 years were eligible if they had treatment-related mortality (TRM) scores of ≤6.9 (corresponding to a predicted risk of early death with standard induction chemotherapy of ≤6.9%) and adequate organ function (LVEF ≥45%, creatinine ≤2.0 mg/dL, bilirubin ≤2.5 times upper limit of normal). Excluded were patients with uncontrolled infection or concomitant illness with expected survival 48 hours that resulted in >7-day delay of the subsequent treatment cycle; 2) grade ≥4 non-hematologic toxicity if recovery to grade ≤2 within 14 days, both excluding febrile neutropenia, infection or constitutional symptoms. Results: Among 33 patients (median age of 57.3 [range: 26-77], median TRM score 2.31 [0.16-5.90]) treated in phase 1, one DLT occurred at dose levels 3 and 4 (respiratory failure in both cases), establishing G-CLAM with mitoxantrone at 18 mg/m2/day as the MTD. Sixty-two patients, including 6 treated in phase 1, received G-CLAM at MTD. Patient characteristics were as follows: median age 58 (21-81) years, median TRM score 2.85 (0.06-6.73), with AML (n=52) or high-risk MDS (n=10). Cytogenetics were favorable in 6, intermediate in 44, and adverse in 12 (MRC criteria); 11 patients had NPM1 and 6 had FLT3 mutations. Fifty-two patients (83.9%, 95% confidence interval: 72.3-92.0%) achieved a CR (n=48 [77.4%: 65.0-87.1%]), or CRp/i (n=4 [6.5%: 1.8-15.7%]) with 1-2 cycles of therapy. Only 3 patients required 2 cycles to best response. Among the 48 CR patients, 43 (89.6%) were negative for measurable residual disease (MRDneg) by flow cytometry. Four patients had morphologic leukemia free state, 1 patient with myeloid sarcoma had a partial remission, 4 had resistant disease, and 1 died from indeterminate cause. One patient died within 28 days of treatment initiation (septic shock). Median times to an absolute neutrophil count ≥500/μL and a platelet count of ≥50,000/μL were 26 and 23 days. Besides infections and neutropenic fever, maculopapular rash, and hypoxia (fluid overload/infection-related) were the most common grade ≥3 adverse events. In addition to the phase 1/2 MTD cohort, there were 15 patients treated in an expansion cohort and 3 eligible patients treated off protocol with mitoxantrone at 18 mg/m2. For these 80 patients combined treated at MTD, the CR and CR/CRp/i rates were 76.3% and 81.2%. After multivariable adjustment, compared to 300 patients treated with 7+3 on the SWOG S0106 trial, G-CLAM with mitoxantrone 18mg/ m2 was associated with an increased probability of CR (odds ratio [OR]= 3.08, p=.02), CR/CRp/i (OR=2.96, p=.03), a trend towards improved MRDnegCR (OR= 3.70, p=.06), and a trend towards improved overall survival ([OS]; hazard ratio=0.34, p=.07). For the entire study cohort, the 6 and 12-month relapse-free survival were 73% (64-83%) and 62% (42-74%) and the 6 and 12-month OS were 89% (82- 96%) and 77% (67-88%). Conclusions: G-CLAM with mitoxantrone up to 18 mg/m2/day is well tolerated and has potent anti-leukemia activity. This regimen may warrant further randomized comparison with 7+3. We also plan to examine the addition of sorafenib to G-CLAM in newly diagnosed AML patients regardless of FLT3 status. Disclosures Othus: Glycomimetics: Consultancy; Celgene: Consultancy. Scott:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Research Funding, Speakers Bureau; Alexion: Speakers Bureau; Agios: Membership on an entity's Board of Directors or advisory committees. Becker:GlycoMimetics: Research Funding. Erba:Ariad: Consultancy; Gylcomimetics: Other: DSMB; Pfizer: Consultancy; Sunesis: Consultancy; Jannsen: Consultancy, Research Funding; Juno: Research Funding; Novartis: Consultancy, Speakers Bureau; Daiichi Sankyo: Consultancy; Celgene: Consultancy, Speakers Bureau; Agios: Research Funding; Astellas: Research Funding; Incyte: Consultancy, DSMB, Speakers Bureau; Celator: Research Funding; Seattle Genetics: Consultancy, Research Funding; Millennium Pharmaceuticals, Inc.: Research Funding; Amgen: Consultancy, Research Funding.