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Gender or Race Does Not Affect Raltegravir Response in Diverse Group
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51st Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), September 17-20, 2011, Chicago
Mark Mascolini
Neither gender nor race affected overall virologic response to raltegravir or adverse event rates in a diverse multinational population of antiretroviral-experienced and naive adults [1]. The study did find modest gender- and race-based virologic response differences in people switching to raltegravir because they could not tolerate their current regimen.
REALMRK is a multicenter, open-label, single-arm observational study planned to assess response to raltegravir in a study group including a high proportion of women and blacks. The trial aimed to enroll mostly antiretroviral-experienced people but also up to 20% of patients starting raltegravir in their first regimen. Everyone took raltegravir at a dose of 400 mg twice daily as part of a combination regimen.
Researchers recruited participants from 34 sites in the United States, Brazil, the Dominican Republic, Jamaica, and South Africa. Of the 209 people enrolled, 98 (47%) were women, 156 (75%) black, and 119 (57%) African American. The study group included 187 people with treatment experience, 98 of whom were taking a failing regimen and 89 of whom could not tolerate their current antiretrovirals. Twenty-two people entered REALMRK with no antiretroviral experience.
Age averaged 44.0 in treatment-experienced people with virologic failure, 46.9 in treatment-intolerant people, and 38.5 in treatment-naive people. Respective proportions of women in those three groups were 47.4%, 50.0%, and 33.3%. Respective proportions of blacks were 72.2%, 78.4%, and 66.7%. Median initial CD4 counts were 190 in the treatment-failure group, 375 in the intolerant group, and 168 in the naive group. Median initial viral loads in those three groups were 15,100 copies, 49 copies, and 85,700 copies. Most study participants (53.4%) also took tenofovir/emtricitabine, 25.7% took darunavir, 21.4% took lopinavir, and 14.6% took atazanavir.
Through 48 weeks of follow-up, 15% of patients overall stopped raltegravir, including similar proportions of women and men (17% and 13%) and blacks and nonblacks (14% and 17%). Among 109 treated men, 14 (13%) stopped therapy, none for lack of efficacy, 1 for adverse events, and 4 because of physician decision. Among 97 treated women, 17 (17.5%) stopped treatment, 1 for lack of efficacy, 5 for adverse events, and 2 because of physician decision. Among 153 black treated participants, 22 (14%) discontinued treatment, none for lack of efficacy, 5 for adverse events, and 5 because of physician decision. Among 53 nonblack treated participants, 9 (17%) stopped treatment, 1 for lack of efficacy, 1 for adverse events, and 1 because of physician decision.
Drug-related clinical adverse event rates were similar in black men (14.3%) and nonblack men (15.4%) and in black women (27.7%) and nonblack women (21.4%). Drug-related lab adverse event rates were also low in black men (2.9%) and nonblack man (2.6%) and in black women (3.6%) and nonblack women (0%).
In a 48-week analysis that excluded people who stopped treatment for reasons other than lack of efficacy or adverse events, proportions with a viral load below 50 copies were 63.8% in the treatment failure group, 76.3% in the intolerant group, and 76.2% in the naive group. Comparing 48-week response rates in men versus women and blacks versus nonblacks according to treatment experience category, the REALMRK team found black-nonblack and male-female differences in the intolerant group:
48-week viral load below 50 copies in people entering with antiretroviral failure:
-- Men 66.0%, women 61.4% (33/50 men, 27/44 women)
-- Blacks 63.8%, nonblacks 64.0% (44/69 blacks, 16/25 nonblacks)
48-week viral load below 50 copies in people entering with antiretroviral intolerance:
-- Men 80.5%, women 71.8% (33/41 men, 28/39 women)
-- Blacks 69.4%, nonblacks 100% (43/62 blacks, 18/18 nonblacks)
48-week viral load below 50 copies in previously untreated people:
-- Men 71.4%, women 85.7% (10/14 men, 6/7 women)
-- Blacks 78.6%, nonblacks 71.4% (11/14 blacks, 5/7 nonblacks)
The response rate difference between men and women in the naive group is hard to interpret because of the small numbers in this category. The investigators did not speculate on the response differences in the antiretroviral-intolerant group. Nor did they report response rates in African Americans versus other blacks. The REALMRK team concluded that raltegravir at the standard dose "had potent efficacy regardless of race or gender."
Reference
1. Squires K, Eron J, Cheng B, et al. Safety, tolerability, and efficacy of raltegravir in a diverse cohort of HIV-infected patients: 48-week results from the REALMRK study. 51st Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC). September 17-20, 2011. Chicago. Abstract H2-789.
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