Phase II trial of dasatinib (DAS) in pediatric patients (pts) with chronic myeloid leukemia in chronic phase (CML-CP).

Abstract

10511 Background: Safe and effective treatment options for newly diagnosed (ND) or imatinib (IM) resistant/intolerant (R/I) pediatric CML pts are limited, and a large prospective study is needed. DAS has proven safety and efficacy in adults with ND or IM-R/I CML and is now being evaluated in a phase II trial of pediatric pts. Methods: CA180-226/NCT00777036 is an open-label nonrandomized prospective study of pts aged <18 y in 3 cohorts: (1) CML-CP R/I to IM treated with DAS tablets 60 mg/m2 QD, (2) IM-R/I CML-AP/BP or Ph+ ALL (enrollment closed early due to poor response), and (3) ND CML-CP treated with DAS tablets 60 mg/m2 or DAS 72 mg/m2powder for oral suspension (PFOS) QD. Primary objectives were major cytogenetic response (MCyR) for CML-CP R/I to IM and complete cytogenetic response (CCyR) for ND CML-CP (MCyR >30% and CCyR >55% considered of clinical interest). Results: 113 pediatric CML-CP pts were treated. Cumulative rate of MCyR >30% was reached as early as 3 mo (55%; [95% CI 36, 74]) for IM-R/I CML-CP. Cumulative rate of CCyR >55% was reached as early as 6 mo (64% [95% CI 53, 74] for ND CML-CP; 61% [95% CI 46, 74] for pts on tablets and 70% [95% CI 51, 84] for pts on PFOS). Estimated PFS by 48 mo was >75% for CML-CP R/I to IM and >90% for ND CML-CP. One CML-CP pt R/I to IM died 1 y after stopping DAS from gastrointestinal bleeding. AEs were consistent with those observed in adults, except no DAS-related pleural/pericardial effusion or pulmonary arterial hypertension (PAH) were reported here. Conclusions: In the largest prospective trial of pediatric pts with CML-CP, target responses were met early and increased over time with DAS treatment. The efficacy and safety of DAS were consistent with previous reports in adults, except no cases of pleural/pericardial effusion or PAH were observed. These results suggest DAS is safe and highly effective in the first- or second-line treatment of pediatric CML-CP. Clinical trial information: NCT00777036. [Table: see text]