Chronic Myeloid Leukemia: Long-Term Outcome Data in the Imatinib Era

Abstract

Recent reports suggest that in the TKI era, the survival of chronic myeloid leukemia approaches that of general population. The real-world situation may be different. We analyzed patients (≥ 18 years) with chronic phase (CP) CML enrolled over a 7-year period (2002-2008) in an imatinib access program. Event was defined as non-achievement/loss of complete hematological response (CHR), loss of cytogenetic response or progression to accelerated (AP)/blast phase (BC). Progression was defined as development of AP/BC. Any delay of ≥ 1 week in reporting for drug refills was categorized as non-adherence. Of the 443 patients with CP-CML who started imatinib [median age: 36 years (18-70); High risk: 32% (Sokal) and 14% (Hasford/EUTOS)], 162 (37%) had received prior therapy [mostly hydroxyurea (N = 153]. CHR was achieved by 430 (97%). After a median follow up of 109.5 months (3.4-184.3), the EFS, PFS and OS at 10 years was 43%, 75% and 76% respectively. Superior EFS was predicted by low-risk Hasford score and adherence to therapy. Adherence to therapy was the only factor which predicted EFS on multivariate analysis (HR 0.64, 95% CI 0.50-0.83, P = 0.001). Long-term follow up of patients with CP-CML reflects poorer survival than those reported from clinical trials and reflects multiple issues that affect "real-world" patients. The continued drop in EFS, noted during long-term follow up, might take time to impact the PFS and OS due to the chronic nature of the disease. Sustained adherence to therapy is important for optimum long-term outcomes.

Keywords: 10-Year survival; Adherence; Chronic myeloid leukemia; Imatinib; Long-term outcomes.

Fig. 1

Survival outcomes. The Kaplan–Meier curves depict the long-term event-free (EFS-1a), progression-free (PFS-1b) and overall survival (OS-1c) of the patients with chronic phase treated with imatinib

Fig. 2

Factors affecting EFS. a shows the difference between EFS among those with low risk (black line) and high risk (gray line) Hasford scores at baseline. b shows the difference in EFS between those who were adherent (black line) and non-adherent (gray line) to therapy. c and d shows the difference in PFS(2c) and OS (2d) among those who were adherent and non-adherent to therapy respectively