Ponatinib offered a better overall survival for chronic myeloid leukemia (CML) patients in chronic phase compared with allogeneic stem cell transplantation (SCT), according to results of a pooled analysis of two cohorts presented at the 57th Annual American Society of Hematology (ASH) Meeting and Exposition in Orlando, Florida. The drug did not fare better for those in accelerated phase or blast crisis.
SCT is currently considered the standard treatment for either accelerated-phase or blast-crisis CML patients, as well as for Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) and chronic-phase CML patients who are resistant or intolerant to at least two tyrosine kinase inhibitors. Ponatinib, approved for CML or Ph+ ALL patients with the T315I mutation, represents an alternative treatment to SCT. “However, differences in outcomes between patients treated with ponatinib and allogeneic SCT have not been analyzed,” wrote authors led by Franck E. Nicolini, MD, PhD, of Centre Hospitalier Lyon Sud in France, in the study abstract.
The authors pooled outcomes for 184 patients from the PACE phase II trial of ponatinib and the European Bone Marrow Transplant registry. All patients had the T315I mutation; 90 were chronic-phase CML patients, 26 were accelerated-phase CML patients, 41 were blast-phase CML patients, and 27 had Ph+ ALL. In total, 128 received ponatinib, and 56 received SCT.
The adjusted median overall survival (OS) was longer in the chronic-phase CML patients treated with ponatinib (median not reached) than with SCT (103.3 months). The hazard ratio (HR) for survival was 0.37 (95% confidence interval [CI], 0.16–0.84; P = .017).
There was no significant difference between treatment groups for accelerated-phase CML. In the blast-crisis group, however, ponatinib was associated with shorter OS, at 7 months vs 10.5 months with SCT, for an HR of 2.29 (95% CI, 1.08–4.82; P = .030). Ph+ ALL patients had a shorter median survival with ponatinib than with SCT (6.7 months vs 32.4 months), though this did not reach significance with an HR of 2.77 (95% CI, 0.73–10.56; P = .136).
There were several differences between the ponatinib and SCT groups at baseline. Ponatinib patients were older, with a median age of 53 years vs 45 years (P = .006), and the median time from diagnosis to intervention was longer with ponatinib than with SCT (58 vs 32 months; P = .029) in chronic-phase CML patients but not in others.
“Allogeneic SCT remains a potential curative therapy for patients with blast-phase CML,” the authors concluded. “However, ponatinib was associated with significantly longer OS than allogeneic SCT in patients with chronic-phase CML that harbor the T315I mutation and could represent a promising therapeutic alternative in this setting, although follow-up remains short to date.”