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Hypersensitivity to abacavir can be detected by screening for HLA-B*5701 and is recommended for HIV-infected individuals who are candidates for the antiviral agent, French researchers report.
"Because the symptoms of hypersensitivity reaction are very unspecific, the true diagnosis of abacavir hypersensitivity can be made by HLA typing, looking for HLA B*5701 positivity," principal investigator Dr. David Zucman of Hopital Necker in Paris said in an interview with Reuters Health.
In a study published in the May 1st issue of the Journal of Acquired Immune Deficiency Syndromes, Dr. Zucman and colleagues retrospectively assessed 49 HIV-positive patients exposed to abacavir. Of these, 16 patients (32.6%) had definite or possible hypersensitivity.
Of the 16, six were HLA B*5701 and abacavir was discontinued in these. Five other patients also discontinued abacavir because of ongoing fever. None of the 38 abacavir-tolerant patients were B*57-positive.
Dr. Zucman's team then prospectively screened 137 abacavir-naive patients from an ethnically mixed population, consisting of 106 whites, 30 African or Caribbean blacks and one Asian. Whites were both European and North African.
Of the group, 128 tested negative for B*57. One of these patients discontinued abacavir therapy probably as a result of hypersensitivity, while 127 tolerated abacavir.
Among the nine who were B*57-positive, six patients were found to be HLA B*5701-positive and abacavir therapy was not started in this group. The other three patients were positive for B*5703 and they tolerated abacavir.
The incidence of hypersensitivity to abacavir dropped from 12% to 0% with prescreening, the investigators calculate, and unwarranted interruption of treatment dropped from 10.2% to 0.73%.
" HLA-B*5701 screening in prevention of abacavir hypersensitivity reaction is useful in all populations except the black population, in which HLA B*5701 is very rare (below 0.5%)," Dr. Zucman said.
"If a patient has already been exposed to abacavir and has developed some symptoms possibly related to abacavir hypersensitivity reaction, the drug has to be stopped immediately," he stressed.
"Second-line treatments for HIV infection are now multiple and their efficacy is comparable to abacavir, especially tenofovir, which is very frequently used," Dr. Zucman observed.
