Trastuzumab for treatment of refractory/relapsed HER2-positive adult B-ALL: results of a phase 2 GRAALL study.

The aim of this phase 2 study was to evaluate the efficacy and safety of trastuzumab, a humanized monoclonal antibody targeted against the human epidermal growth factor receptor 2 (HER2), for adult patients with relapsed/refractory HER2-positive B-ALL. Fifteen patients, with a median age of 62 years, received trastuzumab according to the schedule approved for breast cancer patients (ie, 4 mg/kg intravenous loading dose followed by 2 mg/kg weekly). The overall response rate was 13% with 2 patients achieving partial response and partial remission cytolytic response, respectively. Two other patients were documented with blast clearance. Only 1 reversible grade 3 cardiac toxic event occurred. This phase 2 study showed that trastuzumab monotherapy can allow for some responses in a very high-risk refractory/relapsed HER2-positive adult B-ALL population. Combination of trastuzumab with chemotherapy or other therapeutic monoclonal antibodies should be tested in the future.