A phase II trial of a chemotherapy-free combination of ponatinib and blinatumomab in adults with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL).

Abstract

7009 Background: Ponatinib and blinatumomab are highly active in Ph+ ALL. A chemotherapy-free combination of these agents may lead to durable remissions and reduce the need for stem cell transplant (SCT) in first remission. Methods: In this phase II study, adults with newly diagnosed (ND) Ph+ ALL, relapsed/refractory (R/R) Ph+ ALL, or CML in lymphoid blast phase (CML-LBP) received up to 5 cycles of blinatumomab. Ponatinib 30mg daily was given during cycle 1 and decreased to 15mg daily once a complete molecular response (CMR) was achieved. After completion of blinatumomab, ponatinib was continued for at least 5 years. All patients (pts) received 12 doses of prophylactic IT chemotherapy. Results: Between 2/2018 and 1/2022, 55 pts were treated (35 ND, 14 R/R and 6 CML-LBP). Baseline characteristics and responses are shown in Table. Among 23 pts with ND Ph+ ALL evaluable for response, 22 (96%) achieved CR/CRi; 1 pt had early death due to myelosuppression from prior chemotherapy. Among 13 evaluable pts with R/R Ph+ ALL, 12 (92%) achieved CR/CRi. The CMR rates for the ND, R/R and CML-LBP cohorts were 64%, 71%, and 17% after cycle 1 and were 85%, 79%, and 33% overall, respectively. In the ND cohort, 4/17 evaluable pts (24%) achieved CMR in the peripheral blood within 1 week, and 9/15 (60%) within 2 weeks. The median follow-up is 11 months (range, 1-46+ months). Among the 35 pts in the ND cohort, 33 pts (94%) are alive and in continuous remission. Only 1 pt in the ND underwent SCT in first remission (due to persistent MRD positivity), and no relapses have been observed. The 2-year EFS and OS rates in the ND cohort are 93%. Among the 13 responding pts in the R/R cohort, 6 (46%) underwent SCT. The 2-year EFS and OS rates for the R/R cohort are 42% and 61%, and for the CML-LBP cohort are 33% and 60%, respectively. Most side effects were grade 1-2 and were consistent with the known toxicity profile of the two agents individually. Two pts discontinued ponatinib due to toxicity (1 due to stroke and 1 due to DVT). One pt discontinued blinatumomab due to recurrent neurotoxicity. Conclusions: The chemotherapy-free combination of ponatinib and blinatumomab was safe and effective in Ph+ ALL and CML-LBP. Longer follow-up continues to demonstrate durable remissions, particularly in ND Ph+ ALL, even without SCT in first remission. Clinical trial information: NCT03263572. [Table: see text]