Incidence of abacavir hypersensitivity and its relationship with HLA-B*5701 in HIV-infected patients in Taiwan.

OBJECTIVES To describe the incidence of hypersensitivity to abacavir and frequency of human leucocyte antigen (HLA)-B*5701 in HIV-infected Taiwanese persons. METHODS Medical records of 337 HIV-infected Taiwanese in whom abacavir-containing combination antiretroviral therapy (CART) was prescribed from 1 May 2001 to 31 December 2006 were reviewed, and HLA typing of the patients was performed in 320 patients (232 receiving abacavir and 88 not receiving abacavir) with available blood samples. HLA class I and II polymorphisms were determined by PCR with specific primers. HLA-B*5701 was further confirmed by sequence-based typing. RESULTS Of the 337 patients, median CD4 count was 166.5 cells/mm3 (range, 1.0-1914.0) and 83 patients (24.6%) had AIDS-defining opportunistic infections. Thirty-eight patients (11.3%) discontinued abacavir within 6 weeks of starting abacavir-containing CART. Among them, 10 patients had successful abacavir re-challenge and another 11 patients had other specific reasons for abacavir discontinuation. Therefore, 14 patients (4.2%) were classified as cases in whom abacavir hypersensitivity could not be excluded, and 3 patients (0.9%) met the criteria of abacavir hypersensitivity. Of the 320 patients undergoing HLA typing, HLA-A02 was the most common allele and only one individual (0.3%) expressed HLA-B*5701. Along with some differences in allele distributions, there was a significant difference in the genetic frequency of HLA-B57 in our patients compared with those of previous studies in other Chinese populations. CONCLUSIONS Abacavir hypersensitivity was less frequently encountered in HIV-infected Taiwanese initiating abacavir-containing CART than in Caucasians, which might be explained by the low frequency of the HLA-B*5701 allele.