Efficacy and safety of olverembatinib as maintenance therapy after allogeneic hematopoietic cell transplantation in Philadelphia chromosome–positive acute lymphoblastic leukemia

Experience using olverembatinib as maintenance therapy in patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph⁺ ALL) after allogeneic hematopoietic cell transplantation (allo-HCT) is limited. We retrospectively collected data from 26 patients with Ph⁺ ALL who received only olverembatinib as maintenance therapy after allo-HCT. Olverembatinib was administered as prophylaxis in 18 patients (69.2%), and preemptively in 8 patients (30.8%). The median time of olverembatinib initiation after transplantation was 2.5 months (range, 1-7.3). The median starting dose of olverembatinib was 35 mg qod (range, 15-40). The median duration of olverembatinib treatment was 12.5 months (range, 6-23). Olverembatinib maintenance treatment was discontinued in 8 patients (8/26,30%), seven stopped the drug for a long-lasting BCR-ABL1 negativity and 1 for recurrent fever associated with the drug. BCR-ABL1 turned positive in 3 patients in 2, 3 and 6 months after discontinuation. During olverembatinib treatment, three patients developed grade ≥ 3 hematologic side effects, which resolved with dose interruption or dose reduction. The median follow-up time after allo-HCT were 17.75 months (range 7-31). The hematologic relapse rate was 7.7% (2/26), with no event in the preemptive group. The 3-year probability of overall survival and relapse free survival after allo-HCT was 91.7% and 79.1%, respectively. Only one patient in prophylaxis group died of central central nervous system (CNS) relapse. Thus, our data suggest that olverembatinib is effective and safe as maintenance treatment in patients with Ph⁺ ALL who underwent allo-HSCT. The main adverse effect was hematologic toxicity, which was tolerated.