Outcomes of blast phase chronic myeloid leukemia (BP-CML) in the tyrosine kinase inhibitor (TKI) era.

Abstract

e18546 Background: Primary goal in management of chronic myeloid leukemia (CML) is to prevent progression to BP-CML. Even with the use of induction chemotherapy with a TKI, outcome remains dismal in BP-CML. We describe our experience with the management of BP-CML. Methods: Retrospective chart review was performed on CML patients treated between 2001 and 2016. Out of 585 CML cases, 58 (10%) had a diagnosis of BP-CML. Kaplan-Meier method with log-rank test was utilized for survival calculations. All p-values calculated were two sided. Results: The overall survival (OS) of BP-CML cohort was 31.9 months (mo) from diagnosis. In the patients diagnosed in chronic or accelerated phase, median time to progression to BP-CML was 19.1 mo. The median OS from the BP-CML diagnosis was not different when progressed from an earlier phase compared toBP-CML (10.8 vs 11.0, p 0.62). Trend toward worse OS was noted in myeloid BP-CML compared to lymphoid BP-CML (9.2 vs 17.5 mo, p 0.32). The median OS in the single agent TKI cohort (n=21) was 12.8 mo vs 10.9 mo (p 0.72) in the combination cohort (n = 36). Treatment with a single agent TKI vs combination therapy did not significantly impact OS in either myeloid (9.2 vs 9.1 mo, p 0.32) or lymphoid (14.5 vs 18.3 mo, p 0.24) BP-CML. Out of 26 patients (44.8%) who received allogeneic stem cell transplant, 26% (n=6) received a single agent TKI prior to transplant and 76.9% (n=20) received combination therapy. A trend toward improved OS was noted in the single agent TKI cohort (128.5 vs 24.0 mo, p 0.23). When stratified by the presence of standard Philadelphia chromosome or with additional cytogenetic aberrations, no difference in OS was noted (10.9 vs 12.1 mo, p 0.51). Monosomy 7 was present in greater frequency in lymphoid BP-CML than myeloid BP-CML (35.7% vs 6.3%, p 0.02). Conclusions: Our data suggest no survival difference when BP-CML is treated with a single agent TKI compared to a combination therapy, regardless of histology type. Therefore, single agent TKIs should be considered as an effective frontline therapy option for BP-CML, which may prevent the potential toxicity associated with chemotherapy. These findings need further validation in a larger prospective cohort.