Long-term follow-up of blinatumomab in patients with relapsed/refractory Philadelphia chromosome–positive B-cell precursor acute lymphoblastic leukaemia: Final analysis of ALCANTARA study

AIM: To evaluate long-term durability of blinatumomab, a BiTE® (bispecific T-cell engager) molecule, in adults with relapsed/refractory (R/R) Philadelphia chromosome-positive (Ph+) B-cell precursor acute lymphoblastic leukaemia (ALL). METHODS: In this final analysis of an open-label, single-arm, phase 2, multicentre ALCANTARA study (NCT02000427), adults (age ≥18 years) with Ph+ ALL who had relapsed or were refractory to at least one TKI were included. The primary endpoint was the proportion of patients who achieved complete remission (CR)/CR with partial haematologic recovery (CRh) during the first two cycles of blinatumomab treatment. RESULTS: The final analysis included 45 patients who completed the study between 3rd January 2014 and 6th January 2017, of which 16 (35.6%; 95% CI, 21.9%-51.2%) achieved CR/CRh within the first two blinatumomab cycles. After a median follow-up of 16.1 months, median relapse-free survival (RFS) was 6.8 (95% CI, 4.4-not estimable [NE]) months. Median overall survival (OS) was 9.0 (95% CI, 5.7-13.5) months with a median follow-up of 25.1 months. Median OS in patients with CR (19.8 [95% CI, 12.1-NE] months) was greater than in those without CR (6.0 [95% CI, 2.9-7.1] months). Of 16 patients with CR/CRh, 14 achieved complete minimal residual disease (MRD) response; the median duration of complete MRD response was 9.7 (95% CI, 5.2-NE) months. Treatment-related adverse events were consistent with those previously reported. CONCLUSION: Long-term durability of responses to blinatumomab was demonstrated in patients with R/R Ph+ ALL.