Influence of BCR-ABL Transcript Type on Outcome in Patients With Chronic-Phase Chronic Myeloid Leukemia Treated With Imatinib.

The prognostic significance of breakpoint cluster region gene-Abelson murine leukemia viral oncogene homolog 1 (BCR-ABL1) transcripts in chronic myeloid leukemia (CML) is still controversial. All consecutive CML patients in chronic phase treated with imatinib in a single center were analyzed (n = 170). BCR-ABL1 transcript was evaluated using multiplex reverse transcription polymerase chain reaction. Exclusively patients with BCR-ABL transcripts e13a2 and/or e14a2 were included in this analysis. Patients with e14a2 transcripts presented higher rates of optimal molecular responses at 3 months and higher rates of complete cytogenetic response (CCR) at 6 months. E13a2, e14a2, and e14a2 with e13a2 (e14a2+e13a2) groups presented similar rates of 5-year event-free, progression-free, and overall survival. There was a superior 10-year overall survival in patients with transcripts e13a2 compared with e14a2 (alone or coexpressed with e13a2; 93% vs. 73%; P = .03), although the 5-year overall survival was 96% vs. 88%, respectively (P = not significant). In a multivariate analysis, high/intermediate Sokal score and e14a3/e14a3+e14a2 were independent factors for poor overall survival (hazard risk [HR], 4.63; P = .023 for Sokal score and HR, 10.6; P = .041 for BCR-ABL transcript). Patients with BCR-ABL transcripts e14a2 transcripts have higher rates of CCR at 6 months and higher rates of optimal molecular response at 3 months compared with e13a2 or with both transcripts, but no difference in 5-year overall, progression-free, and event-free survival. There was a superior 10-year overall survival among patients with transcripts e13a2 compared with e14a2 (alone or coexpressed with e13a2).