OBJECTIVESThe advent of the tyrosine kinase inhibitors has markedly changed the prognostic outlook for patients with Ph+ and/or BCR-ABL1+ chronic myeloid leukemia (CML). This study was designed to assess the overall survival (OS) of Nigerian patients with CML receiving imatinib therapy and to identify the significant predictors of OS.METHODSAll patients with CML receiving imatinib from July 2003 to June 2013 were studied. The clinical and hematological parameters were studied. The Kaplan–Meier technique was used to estimate the OS and median survival. P-value of <0.05 was considered as statistically significant.RESULTSThe median age of all 527 patients (male/female = 320/207) was 37 (range 10–87) years. There were 472, 47, and 7 in chronic phase (CP), accelerated phase, and blastic phase, respectively. As at June 2013, 442 patients are alive. The median survival was 105.7 months (95% confidence interval [CI], 91.5–119.9); while OS at one, two, and five years were 95%, 90%, and 75%, respectively. Multivariate Cox regression analysis revealed that OS was significantly better in patients diagnosed with CP (P = 0.001, odds ratio = 1.576, 95% CI = 1.205–2.061) or not in patients with anemia (P = 0.031, odds ratio = 1.666, 95% CI = 1.047–2.649). Combining these variables yielded three prognostic groups: CP without anemia, CP with anemia, and non-CP, with significantly different median OS of 123.3, 92.0, and 74.7 months, respectively (χ2 = 22.042, P = 0.000016).CONCLUSIONThis study has clearly shown that for Nigerian patients with CML, the clinical phase of the disease at diagnosis and the hematocrit can be used to stratify patients into low, intermediate, and high risk groups.

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The distribution of BCR-ABL1 transcript variants e13a2 (''b2a2'') and e14a2 (''b3a2'') in Nigerians with chronic myeloid leukemia (CML) had not been previously studied. In addition, there is paucity of data on the impact of BCR-ABL1 transcript variants on clinical presentation and survival in CML patients in Nigeria. The BCR-ABL1 transcript variants were analyzed in 230 Imatinib-treated CML patients at diagnosis. Patients with incomplete data (n = 28), e19a2 (n = 3) and e1a2 (n = 1) were excluded from analysis of transcript variant on disease presentation and survival leaving only 198. The frequencies of BCR-ABL1 transcript variants were 30 (13.0%), 114 (49.6%), 82 (35.7%), three (1.3%) and one (0.4%) for e13a2, e14a2, coexpression of e13a2/e14a2, e19a2 and e1a2, respectively. A significantly higher platelet count was found in patients with e13a2 variant (531.1 ± 563.4 9 10 9 /L) than in those expressing e14a2 (488.2 ± 560.3 9 10 9 /L) or e13a2/e14a2 (320.7 ± 215.8 9 10 9 /L); p = 0.03. No significant differences were found between the variants with regards to gender, age, phase of disease at diagnosis, total white blood cell count, neutrophil percentage, hematocrit, splenomegaly or hepatomegaly. Overall survival was higher but not statistically significant (p = 0.4) in patients with e14a2 variant (134 months) than in e13a2 (119 months) and coexpression of e13a2/e14a2 (115 months). Nigerian CML patients have the highest incidence of co-expression of e13a2 and e14a2. Distinct disease characteristics which contrast with findings from the Western countries were also identified in Nigerians which may be due to genetic factors.