Effects of Imatinib mesylate (Glivec) on some circulating immunocytes in a group of Nigerians with Chronic Myeloid Leukaemia: a preliminary study

Abstract

AIM Glivec is a selective inhibitor of the bcr/abl tyrosine kinase, deregulated expression of which is involved in the pathogenesis of chronic myeloid leukaemia (CML). Reports of tuberculosis and lymphopenia in CML patients on Glivec who are not exposed to mycobacterial infection and are HIV negative have suggested the possibility of immunosuppressive properties  for Glivec; and hence the need to investigate its effects in Nigerian CML patients currently on the drug.

METHODS Baseline complete blood count (CBC) and CD4+ T lymphocyte count of confirmed Ph+ CML patients were done pre-Glivec therapy and while on the drug.  CBC was done using manual method, while absolute lymphocyte count (ALC) was calculated from the total WBC and the differential count for lymphocytes. CD4+ lymphocyte counts were done using Cyflow automatic cell counter. Glivec, at a dose of 400mg, was used for between 12 and 68 weeks before a repeat CBC and circulating CD4+ lymphocyte count were done.

RESULTS Ten patients with a mean (±SD) age of 41.90 ± 8.034 years were investigated. The mean CD4+ lymphocyte count while on imatinib therapy (841.80 ± 373.57/µL) was significantly lower (p = 0.003) than the pre-therapy mean (1774.50 ± 1044.0/µL). There was also a significant reduction (p = 0.009) in the mean absolute lymphocyte count (ALC) from 20071.20 ± 17267.99/µL pre-therapy to 2696.60 ± 1587.69/µL post therapy. The reduction in circulating CD4+ lymphocytes correlated (r = +0.67, p = 0.35) with reduction in ALC.

CONCLUSION Glivec appears to cause significant lymphopaenia. The clinical significance of this finding requires further study.