Clofarabine with topotecan, vinorelbine, and thiotepa reinduction regimen for children and young adults with relapsed AML

Effective reinduction regimens are needed for children with relapsed and refractory acute myeloid leukemia (AML), as outcomes remain poor. Therapeutic options are limited in this heavily pretreated patient population, many of whom have reached lifetime recommended doses of anthracycline chemotherapy. The development of effective non-anthracycline-based salvage regimens is crucial to these patients who are at significant risk of life-threatening cardiotoxicity. We previously reported results of a phase 2 trial of a clofarabine-based regimen with topotecan, vinorelbine, and thiotepa (TVTC) in patients with relapsed acute leukemias. Here we report on an expanded bicenter cohort of 33 patients, <25 years of age, with relapsed/refractory AML treated with up to 2 cycles of the TVTC reinduction regimen from 2007 to 2018. The overall response rate, defined as complete remission or complete remission with partial recovery of platelet count, was 71.4% (95% confidence interval CI, 41.9-91.6) for those patients in first relapse (n = 14) and 47.4% (95% CI, 24.4-71.1) for patients in second or greater relapse or with refractory disease. Responses were seen across multiple high-risk cytogenetic and molecular subtypes, with 84% of responders successfully bridged to allogeneic stem cell transplantation. The 5-year overall survival for patients in first relapse was 46.2% (95% CI, 19.1-73.3) and 50.0% (95% CI, 26.9-73.1) for patients who responded to TVTC. For pediatric and young adult patients with relapsed/refractory AML, TVTC reinduction compares favorably with currently used salvage regimens and warrants further exploration.