Late presentation of chronic myeloid leukaemia patients in a low-income country: the prognostic implications and impact on treatment outcome.

Background: In Nigeria, since 2002, Imatinib mesylate (glivec^®) has been available freely to chronic myeloid leukaemia (CML) patients but only at a tertiary health care centre in the southwestern part of the country. Despite this, it is not readily accessible to many patients due to the distance and other challenges including low socioeconomic status and political problems, preventing timely access to specialist care. This study evaluated the effect of the baseline characteristics on the prognostic implication and treatment outcome of CML patients in Nigeria.

Method: This study retrospectively evaluated the baseline characteristics, clinical presentations and treatment outcomes of 889 CML patients over 18 years (2002-2020). Of these, 576 (65%) patients had complete information with up-to-date BCR::ABL1 records. These 576 patients were categorized based on their responses to Imatinib therapy into three groups viz.; Optimal response (OR) defined as BCR::ABL1 ratio of < 0.1% or major molecular remission (≥ 3-log reduction of BCR::ABL1 mRNA or BCR::ABL1 ratio of < 0.1% on the International Scale), Suboptimal response (SR) with BCR::ABL ratio of 0.1-1%, and Treatment failure (TF) when MMR has not been achieved at 12 months. The variables were analyzed using descriptive and inferential statistics and a p-value < 0.05 was considered statistically significant.

Results: The result revealed a median age of 37 years at diagnosis with a male-to-female ratio of 1.5:1. The majority (96.8%) of the patients presented with one or more symptoms at diagnosis with a mean symptom duration of 12 ± 10.6 months. The mean Sokal and EUTOS scores were 1.3 ± 0.8 and 73.90 ± 49.09 respectively. About half of the patients presented with high-risk Sokal (49%) and EUTOS (47%) scores. Interestingly, both the Sokal (r = 0.733, p = 0.011) and EUTOS (r = 0.102, p = 0.003) scores correlated positively and significantly with the duration of symptoms at presentation. Based on response categorization, 40.3% had OR while 27.1% and 32.6% had SR and TF respectively.

Conclusion: This study observed a low optimal response rate of 40.3% and treatment failure rate of 32.6% in our CML cohort while on first-line Imatinib therapy. This treatment response is strongly attributable to the long duration of symptoms of 12 months or more and high Sokal and EUTOS scores at presentation. We advocate prompt and improved access to specialist care with optimization of tyrosine kinase inhibitor therapy in Nigeria.