Ponatinib vs. Imatinib as Frontline Treatment for Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia: A Matching Adjusted Indirect Comparison

Abstract

Introduction: Efficacy of ponatinib-based treatment for patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL) has not been compared to imatinib-based treatments in head-to-head clinical trials. We evaluated its efficacy versus imatinib-based regimens using a matching adjusted indirect comparison.

Methods: Two ponatinib studies were used: the phase 2 MDACC study of ponatinib + hyper-CVAD (cyclophosphamide, vincristine, doxorubicin, and dexamethasone) in adult patients and the phase 2 GIMEMA LAL1811 study of ponatinib + steroids in patients > 60 years/unfit for intensive chemotherapy and stem cell transplant. Studies on imatinib as first-line treatment in adults with Ph + ALL were identified using a systematic literature search. Population adjustment was based on the prognostic factors and effect modifiers identified by clinical experts. Hazard ratios (HRs) were calculated for overall survival (OS) and odds ratios (ORs) for complete molecular response (CMR).

Results: The systematic literature search identified two studies (GRAAPH-2005 and NCT00038610) reporting the efficacy of first-line imatinib + hyper-CVAD and one study reporting the efficacy of first-line imatinib monotherapy induction + imatinib-based consolidation (CSI57ADE10). Ponatinib + hyper-CVAD prolonged OS and gave a higher CMR rate than imatinib + hyper-CVAD. The adjusted HR [95% confidence interval (CI)] for OS was 0.35 (0.17-0.74) for MDACC vs. GRAAPH-2005 and 0.35 (0.18-0.70) for MDACC vs. NCT00038610; the adjusted OR (95% CI) for CMR was 12.11 (3.77-38.87) for MDACC vs. GRAAPH-2005 and 5.65 (2.02-15.76) for MDACC vs. NCT00038610. Ponatinib + steroids prolonged OS and gave a higher CMR rate than imatinib monotherapy induction + imatinib-containing consolidation. The adjusted HR (95% CI) for OS was 0.24 (0.09-0.64) and the adjusted OR (95% CI) for CMR was 6.20 (1.60-24.00) for GIMEMA LAL1811 vs. CSI57ADE10.

Conclusion: In adults with newly diagnosed Ph + ALL, first-line treatment with ponatinib was associated with better outcomes than first-line treatment with imatinib.

Keywords: Acute lymphoblastic leukemia; Efficacy; Imatinib; Indirect treatment comparison; Matching adjusted indirect comparison; Philadelphia chromosome; Ponatinib; Tyrosine kinase inhibitor.