Treatment outcomes in 477 patients with blast-phase CML

This study examined treatment outcomes in patients with blast-phase chronic myeloid leukemia (CML). Authors reported that intensive treatment early followed by stem cell transplantation remains as the most effective approach. Certain patient characteristics and treatment history are significant predictors of outcomes. 

CML has 3 phases: chronic, accelerated, and blast. Patients are generally diagnosed in the chronic phase. Long-term treatment with tyrosine kinase inhibitor (TKI) therapy, such as imatinib (Gleevac), is standard. TKIs have greatly increased survival in chronic-phase CML. However, some patients still transform to blast phase. The average survival with blast-phase CML is less than 12 months. Blast-phase CML can have different classifications and treatment needs. Finding predictive factors of treatment is important to help improve outcomes. 

The aim of this study was to examine predictive factors for blast-phase CML outcomes.

The records of 477 blast-phase CML patients were analyzed. All patients had a history of TKI therapy. Patients characteristics and treatment outcomes were recorded over an average period of 11.5 months.

The average age of patients was 53 years. 64% of patients were men. 80% of patients were diagnosed with CML in the chronic phase, which transformed to blast phase after an average period of 41 months. 5% of patients had accelerated-phase CML at diagnosis, which transformed to blast phase after an average period of 14 months. 71 patients (15%) had blast-phase CML at diagnosis.

72% of patients received TKI therapy before transformation to blast phase. 35% received TKI alone as a first-line therapy. 46% received a TKI with a chemotherapy. 19% received a first-line therapy not involving a TKI. Patients initially treated with a TKI plus a chemotherapy showed significantly higher treatment response rates.

Average overall survival (time from treatment until death from any cause) was 12 months. 87% of patients dialed first-line treatments. The average time until treatment failure was 5 months.

Prior TKI therapy, an age of 58 years or older, high lactate dehydrogenase levels (a measure of cell damage), no history of a stem cell transplant, transition to blast phase from chronic or accelerated phase, and abnormalities on chromosome 15 all significantly increased mortality risk. Achieving good treatment response to first-line treatment was also found to predict better survival. The combination of a TKI with intensive chemotherapy followed by a stem cell transplant was associated with the best outcomes. 

This study reported on predictors of treatment outcomes for blast-phase CML. Treatment with a combination of TKIs and chemotherapy followed by a stem cell transplant was found to be the most effective approach.