A phase II study of dasatinib therapy in children and adolescents with newly diagnosed chronic phase chronic myelogenous leukemia (CML-CP) or Philadelphia chromosome-positive (Ph+) leukemias resistant or intolerant to imatinib.

Abstract

TPS9594 Background: Dasatinib is a BCR-ABL inhibitor approved for treatment in adult patients (pts) with newly diagnosed Ph+ CML-CP; CML resistant/intolerant to prior therapy, including imatinib; and Ph+ acute lymphoblastic leukemia (ALL). There are no established dasatinib treatment regimens for children/adolescents with relapsed/refractory leukemia, but pediatric trials are underway. A phase I dose-escalation study of dasatinib in pediatric pts with refractory solid tumors (n=28) and imatinib-refractory, Ph+ leukemia (n=11) reported a maximum tolerated dose of 85 mg/m2 twice daily in solid-tumor pts and at least a partial cytogenetic response (CyR) in all evaluable CML pts (n=9) (Aplenc, J Clin Oncol 2011). Preliminary results from a phase I dose-escalation study in pediatric pts with subtypes of relapsed/refractory leukemia (NCT00306202) indicate that dasatinib was well tolerated up to 120 mg/m2 (Zwaan, Blood 2010 [abstr 2265]). Further study of dasatinib in pediatric pts is warranted. Methods: To evaluate the safety and efficacy of dasatinib monotherapy in children/adolescents with newly diagnosed CML-CP or Ph+ leukemias resistant/intolerant to imatinib, a phase II nonrandomized, global study of dasatinib in pts birth to <18 y is ongoing (NCT00777036): Cohort 1 (C1), Ph+ CML-CP pts resistant/intolerant to imatinib; Cohort 2 (C2), Ph+ ALL, accelerated or blast phase CML pts resistant/intolerant to or relapsed after imatinib therapy; or Cohort 3 (C3), newly diagnosed, treatment-naïve Ph+ CML-CP pts. Treatments are once daily with dasatinib 60 mg/m2 (C1/C3) or 80 mg/m2 (C2) for ≥24 months. Primary endpoints are major CyR (C1), complete hematologic response (C2), and complete CyR (C3). Secondary endpoints include safety, tolerability, best response, time to/duration of response, survival, and molecular response rates. BCR-ABL mutations are evaluated. First patient first visit was March 2009; estimated trial completion is September 2016. As of January 2012, 63 pts (n=27 aged <12 y; n=36 aged ≥12 y) have been treated in C1/C2 (n=41) and C3 (n=22). Enrollment is ongoing at 79 sites.