Do All Racial/ethnic Groups Need HLA-B*5701 Screening before Starting Abacavir (Ziagen, Epzicom)?

By Liz Highleyman

An estimated 3%-8% of patients who take the NRTI abacavir (Ziagen; also in the Epzicom and Trizivir fixed-dose combination pills) may develop a potentially severe allergic hypersensitivity reaction, usually within the first 6 weeks after starting the drug. Individuals who experience such a reaction should not take abacavir again, since doing so can be life-threatening.

Researchers found that a specific human genetic variation known as the HLA-B*5071 allele is strongly associated with susceptibility to abacavir hypersensitivity. Studies showed that a genetic test for HLA-B*5071 can accurately predict which patients are at risk for hypersensitivity, enabling them to avoid the drug.

The HLA-B*5701 variation is not distributed evenly among different racial/ethnic groups, being most common among people of Northern European descent and less so among people of African or Asian descent. Researchers have evaluated the validity of the genetic test in black and white Americans, but Asians have not been well studied.

At the 48th International Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2008) in late October, Korean researchers presented data from a study evaluating the frequency of the HLA-B*5701 allele and its predictive value for abacavir hypersensitivity in 534 Korean patients with HIV.

Blood samples were tested for the genetic variation and medical records of 150 patients who had taken abacavir were reviewed. Abacavir hypersensitivity was defined as occurrence of more than 2 symptoms -- fever, rash, gastrointestinal symptoms, respiratory problems, or constitutional symptoms -- that resolved soon after abacavir discontinuation.

Results

• None of the 534 Korean patients tested had the HLA-B*5701 variation.

• Of the 150 patients who received abacavir, 15 (10%) discontinued within 6 weeks and 6 (4%) met the criteria for abacavir hypersensitivity reaction.

• None of the patients who discontinued abacavir carried the HLA-B*5701 allele.

"HLA-B*5701 was significantly less frequent in HIV-infected Korean than in white and black patients," the investigators concluded.

"No patient with clinically suspected abacavir hypersensitivity in this study had HLA-B*5701," they continued. "These findings strongly suggest that HLA-B*5701 screening test is not cost-effective in Korean HIV patients."

Seoul National Univ. Hospital, Seoul, Republic of Korea.

12/9/08

Reference
WB Park, PG Choe, KH Song, and others. Is HLA-B*5701 Screening Needed before Starting Abacavir in Every Race? 48th International Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2008). Washington, DC. October 25-28, 2008. Abstract H-2293.