Shorter treatment for latent TB infection?

Three months of weekly rifapentine plus isoniazid for treatment of M. tuberculosis infection in HIV co-infected persons. 

Sterling TR, Scott NA, Miro JM, Calvet G, La Rosa A, Infante R, Chen MP, Benator DA, Gordin F, Benson CA, Chaisson RE, Villarino ME, Tuberculosis Trials Consortium, the AIDS Clinical Trials Group for the PREVENT TB Trial (TBTC Study 26 ACTG 5259). AIDS. 2016 Mar 17. [Epub ahead of print]

Objective: Compare the effectiveness, tolerability, and safety of three months of weekly rifapentine plus isoniazid under direct observation (3HP) vs. 9 months of daily isoniazid (9H) in HIV-infected persons.

Design: prospective, randomized, open-label non-inferiority trial.

Setting: U.S., Brazil, Spain, Peru, Canada, and Hong Kong.

Participants: HIV-infected persons who were tuberculin skin test positive or close contacts of tuberculosis cases.

Intervention: 3HP vs. 9H.

Main outcome measures: The effectiveness endpoint was tuberculosis; the non-inferiority margin was 0.75%. The tolerability endpoint was treatment completion; the safety endpoint was drug discontinuation due to adverse drug reaction.

Results: Median baseline CD4+ counts were 495 (IQR: 389-675) and 538 (IQR: 418-729) cells/mm3 in the 3HP and 9H arms, respectively (P = 0.09). In the modified intention to treat analysis, there were two tuberculosis cases among 206 persons (517 person-years (p-y) of follow-up) in the 3HP arm (0.39 per 100 p-y) and six tuberculosis cases among 193 persons (481 p-y of follow-up) in the 9H arm (1.25 per 100 p-y). Cumulative tuberculosis rates were 1.01% vs. 3.50% in the 3HP and 9H arms, respectively (rate difference: -2.49%; upper bound of the 95% confidence interval (CI) of the difference: 0.60%). Treatment completion was higher with 3HP (89%) than 9H (64%) (P < 0.001), and drug discontinuation due to an adverse drug reaction was similar (3% vs. 4%; P = 0.79) in 3HP and 9H, respectively.

Conclusions: Among HIV-infected persons with median CD4+ count of approximately 500 cells/mm3, 3HP was as effective and safe for treatment of latent M. tuberculosis infection as 9H, and better tolerated.

Abstract access 

Editor’s notes: People with HIV are at higher risk of reactivation of latent tuberculosis (TB). The standard treatment for latent TB, with six to nine months of daily isoniazid, is effective, but treatment completion rates are typically low, and implementation has been poor. Shorter, effective regimens to treat latent TB are therefore necessary, and rifapentine and isoniazid, given weekly for 12 weeks, is one such candidate regimen. The analysis reported in this paper is a sub-study of a larger trial which was reported in 2011 (Sterling et al, NEJM 2011;365:2155). The main trial was open to people regardless of HIV status, but few HIV-positive people were enrolled. Trial enrolment was therefore continued for HIV-positive people, and this paper reports outcomes among this group.

Although the number of tuberculosis events was very small in this sub-study (two versus six people developed tuberculosis in the rifapentine-isoniazid versus isoniazid only arms), the rifapentine-isoniazid regimen, given directly-observed, was non-inferior to self-administered isoniazid, similar to the results of the main trial. Treatment completion was substantially better with the rifapentine-isoniazid regimen, as expected for a shorter regimen given under direct observation. The rifapentine-isoniazid regimen was equally well-tolerated to the isoniazid-only regimen.

This study provides evidence that rifapentine-isoniazid has potential as an alternative to isoniazid for the treatment of latent tuberculosis among HIV-positive people. Several questions remain. Weekly directly-observed therapy could be difficult to implement in resource-limited settings, especially if people are required to travel to health centres to receive their weekly dose, and the effectiveness of this regimen is uncertain when self-administered. The weekly dose represents a substantial pill burden unless combination tablets are available, and there are potential drug interactions between rifapentine and some antiretroviral agents. Further research is necessary to establish whether, in settings where the risk of tuberculosis reinfection is high, a single 12-week course of rifapentine-isoniazid has a long-lasting effect.

Comorbidity, HIV Treatment
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