Phase II Study of Combination of Hypercvad with Ponatinib in Front Line Therapy of Patients (pts) with Philadelphia Chromosome (Ph) Positive Acute Lymphoblastic Leukemia (ALL)

Background: Combination of cytotoxic chemotherapy with tyrosine kinase inhibitors (TKIs) is effective in the treatment of Ph+ ALL. Ponatinib is a more potent BCR-ABL inhibitor. It also suppresses the T315I clones, a common cause of relapse in pts with Ph+ ALL. The combinations of chemotherapy and ponatinib may be associated with better response rates and higher likelihood of eradication of minimal residual disease (MRD) than those reported with other TKIs.

Methods: Pts with newly diagnosed Ph+ ALL received 8 cycles of hyper-CVAD (fractionated cyclophosphamide, vincristine [VCR], doxorubicin, dexamethasone) alternating with high dose methotrexate (MTX) and cytarabine every 21 days. Ponatinib was given at 45 mg po daily for the first 14 days of cycle 1 then continuously for the subsequent 7 cycles. Pts in CR received maintenance with ponatinib 45 mg po daily and vincristine and prednisone monthly for 2 years followed by ponatinib indefinitely. MRD monitoring was conducted.

Results: To date, 34 pts with untreated Ph+ ALL and 3 pts previously treated (1 previous course) have received a median of 6 cycles (2-8); 10 pts are receiving maintenance in CR. 3 pts have completed the 2 years of maintenance and they are receiving single agent TKI. Median WBC at diagnosis was 8 x 10⁹/L (0.9 -629 x 10⁹/L). CD20 expression was reported positive in 11 pts (30%). 3 (8%) had concomitant CNS disease at diagnosis. All pts were in CR after cycle 1. 30/32 pts (94%) with Ph+ metaphases by CG analysis at baseline achieved CCyR after 1 cycle; 1 had mCyR only and 1 had no CG analysis at CR, both of them achieved CCyR after cycle 2. To date, 35 pts (95%) achieved MMR and 26 (70%) CMR. The median time to MMR and CMR were 3 and 10 weeks, respectively. MRD is negative in 35/36 (97%) pts, in whom a sample was sent for assessment. 9 (24%) received an allogeneic stem cell transplantation (ASCT) after a median of 4 cycles (3-10). Median time to neutrophil and platelet recovery for cycle 1 was 18 and 23 days, and 16 and 22 days for subsequent cycles, respectively. Grade ≥ 3 toxicity included infections during induction in 18 pts (49%), increased LFT’s in 12 (32%), thrombotic events in 3 (8%), myocardial infarction (MI) in 3 (8%, 2 unexplained, 1 in the context of sepsis ), skin rash in 4 (11%), and pancreatitis in 6 (16%). With a median follow up of 18 months (9-31), 31 pts are alive, 6 died in CR. 1 pt died in CR from an unrelated cardiac event after being taken off therapy and placed on imatinib, 1 from MOF (C2D13), 1 from NSTEMI (C2D41), 1 from potential MI (C4D42), 1 from head injury sustained after a fall (C4D13), and 1 from sepsis post ASCT. At the last follow-up, 8 pts (19%) are alive post ASCT; 13 pts remain on ponatinib at the dose of 15 mg daily in 14 and 30 mg daily in 1; Of the other 9 alive patients, 7 were switched to dasatinib, two were switched to imatinib and nilotinib (one each); 1 was lost of follow-up. All but one pt who switched to dasatinib remained in CR; the latter relapsed after a first remission of 10 months; she is receiving salvage therapy in combination with dasatinib. The 1-year progression-free and overall survival rates were 96% and 86%, respectively.

Conclusion: The combination of hyperCVAD with ponatinib is highly effective in pts with Ph+ ALL. Due to the vascular events observed, some pts switched to alternative TKI; in the remaining, ponatinib dose was modified to 30 mg daily during consolidation with subsequent reduction to 15 mg in pts in CMR.