Review of methods for TPMT biomarker genotyping in the personalisation of thiopurine therapy

Abstract

Thiopurines, such as azathioprine, are used to treat leukaemias, Crohn’s disease, rheumatoid arthritis, and as

immunosuppressants after organ transplantation. Thiopurines are metabolised by thiopurine S-methyltransferase

(TPMT) and impaired TPMT enzyme activity results in accumulation of thiopurines and toxic effects on bone marrow.

TPMT-deficient patients are poor metabolisers and can be treated successfully and safely with reduced azathioprine

doses if TPMT metaboliser status is identified by pharmacogenetic testing. Azathioprine has a ‘Testing recommended’

drug label annotation by the United States Food and Drug Administration.