Low-intensity chemotherapy (mini-HCVD) and ponatinib followed by blinatumomab (blina) and ponatinib for the treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph plus ALL): A phase II study

e19028 Background: The combination of mini-HCVD and ponatinib followed by blina and ponatinib may improve outcomes compared with HCVAD/ponatinib in patients (pts) with Ph+ ALL while reducing toxicity and the need for ASCT. Methods: Pts with newly diagnosed (ND) or relapsed/refractory (R/R) Ph+ ALL, or chronic myeloid leukemia in lymphoid blast phase (CML-LBP) were eligible. Mini-HCVD alternating with methotrexate (MTX)/cytarabine were given on Cycles(C) 1-4, followed by blina/ponatinib on C5-8. Pts received ponatinib 30mg daily in C1, with dose reduction to 15mg daily once in complete molecular response (CMR). Rituximab was given for CD20+ disease. Maintenance was with ponatinib and vincristine/prednisone for 15 cycles alternating with blina/ponatinib every 3 cycles, followed by ponatinib for at least 5 years. All pts received 12 intrathecal chemotherapy injections. Results: 17 pts (11 ND, 3 R/R, 3 CML-LBP) were treated between 11/2019 and 7/2022 (Table). BCR:ABL1 transcripts were p190 in 7 (64%) pts in the ND cohort. In the ND cohort, 4 (36%) pts had BCR:ABL1 in myeloid cells by FISH and 1 (9%) had a small population of myeloid blasts, suggesting a myeloid component. None of the pts with CML-LBP had received prior therapy. All evaluable pts achieved CR. Among evaluable pts in the ND, R/R, and CML-LBP cohorts, CMR was achieved in 6/8 (75%), 2/2 (100%), and 2/3 (67%) pts, respectively. 2 of the 5 ND pts who had evidence of myeloid involvement did not achieve CMR (1 had negative MRD by NGS). With a median follow-up of 28 months (range, 6-37), the 2-year continuous remission duration and OS rates were 93% and 82% in the entire cohort, and 90% and 82% in the ND cohort, respectively. In the ND cohort, 1 (9%) pt had isolated CNS relapse, 3 (27%) pts died (2 in CR due to COVID-19 and 1 of ASCT complications), and 7 (64%) pts are in remission without ASCT. No pts relapsed in the R/R cohort, 1 pt underwent ASCT, 1 pt died in CR from MTX-associated disseminated necrotizing leukoencephalopathy, and 1 pt is in remission without ASCT. None of the CML-LBP relapsed; 1 pt underwent ASCT in CR. Ponatinib dose was reduced in 2 pts prior to obtaining CMR (1 pancreatitis, 1 cardiomyopathy). One pt switched from ponatinib to dasatinib due to pulmonary embolism in C2. No pts required dose modification of blina. The 60-day mortality rate was 0%. Conclusions: In Ph+ ALL, the sequential combination of mini-HCVD/ponatinib followed by blina/ponatinib resulted in high rates of CMR, encouraging survival, and had an acceptable safety profile. Clinical trial information: NCT03147612 . [Table: see text]