Tenofovir-based PrEP could ‘markedly decrease’ HIV, HBV coinfection
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The use of oral tenofovir-based PrEP for HIV prevention in hepatitis B-endemic countries and in high-risk populations could “markedly decrease” the number of HIV and HBV coinfections, researchers found in a review.
However, the benefit depends on being able to retain patients in care long term and monitor people with inactive disease, the researchers said, noting the risk for acute liver failure among patients with HBV who discontinue PrEP.
Amir M. Mohareb, MD, an infectious disease fellow at Massachusetts General Hospital and Brigham and Women’s Hospital in Boston, said that because tenofovir can inhibit both HIV and hepatitis B, “clinicians and policymakers should be aware of the dual impact that PrEP can have on both of these conditions.”
“We undertook this review because we noted that while PrEP is being scaled up around the world, especially in sub-Saharan Africa, detailed guidance regarding PrEP use in people living with chronic hepatitis B was somewhat lacking,” Mohareb told Healio. “Many of the countries that are expanding access to oral tenofovir-based PrEP do not have robust hepatitis B screening and treatment programs.”
To gather more data on the risks and benefits of tenofovir-based PrEP use in people with HBV, Mohareb and colleagues searched PubMed, the Cochrane Database of Systematic Reviews and Google Scholar for relevant studies using the keywords “hepatitis B” combined with “pre-exposure prophylaxis,” “PrEP,” “treatment withdrawal,” “antiviral cessation,” or “finite treatment duration.”
They included studies and gray literature published between Jan. 1, 2000, and Oct. 1, 2021, and excluded references on non-tenofovir-based regimens for HBV therapy or HIV PrEP.
Their review determined that oral tenofovir-based PrEP has the potential to “greatly benefit” people with HIV and HBV because it is dually active against both infections, Mohareb said.
Data showed that tenofovir disoproxil fumarate (TDF)-based PrEP led to an up to 94% lower incidence of HIV among people at high risk. Even after accounting for “modest adherence,” it reduced HIV incidence and was deemed cost-effective in a variety of settings and populations.
Additional data from the U.S. showed that TDF/emtricitabine — the most prescribed antiviral regimen for PrEP — also “potently inhibits HBV DNA replication” and “functionally serves as HBV treatment,” although it is not an approved treatment combination for HBV.
According to the study, TDF monotherapy reduced HBV after only 4 weeks of therapy, with maximum reductions observed after 18 months. Among people in HBeAg-negative phases of chronic HBV, 93% of participants enrolled in clinical trials had undetectable amounts of HBV DNA at 1 year. Comparable outcomes were seen in real-world studies of the therapy in people in HBeAg-negative phases of chronic HBV in Europe, where 90% of people had undetectable amounts of HBV DNA after 1 year; India, where 92% had undetectable amounts after 1 year; and Ethiopia, where 85% had undetectable amounts after 1 year.
“PrEP represents an opportunity for some people living with chronic hepatitis B to be started on effective hepatitis B treatment,” Mohareb said. “However, PrEP prescribers should be aware of the potential for risks when people living with hepatitis B stop tenofovir-based PrEP.”
According to the study, abrupt cessation has been associated with HBV DNA reactivation and hepatitis flares, with some people developing acute liver failure. Additionally, the initiation of TDF-based PrEP could lead to the need for lifelong treatment with antiviral therapy. The authors said these concerns most likely led to the exclusion of people with HBV infection from most PrEP clinical trials.
“Even though most clinical trials of oral, tenofovir-based PrEP excluded people living with hepatitis B, clinicians should not shy away from prescribing these medicines to people living with hepatitis B,” Mohareb said. “More intensive laboratory monitoring is needed for PrEP users who live with hepatitis B. Ultimately, the risk of liver injury following PrEP cessation needs to be weighed against the risk of HIV acquisition without PrEP.”
Perspective
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This study emphasizes that more research is needed to safely scale up tenofovir-based PrEP in people with HBV. Studies are specifically needed that focus on people with HBV who do not meet treatment criteria based on current guidelines. However, 296 million people live with HBV, and only 10% are diagnosed.
In resource-limited settings with the highest burden of HBV (such as the African, South-East Asian and Western Pacific regions), few people with HBV are aware of their infection, and access to HBV management and treatment is scarce. And although screening for HBV is recommended before administering PrEP, it is unlikely that this is routine practice — and the repercussions for stopping PrEP can be quite dangerous, especially for people who are unaware that they have HBV and/or those who can’t access ongoing monitoring of liver health.
Our primary concern needs to be improving access to HBV screening, management and treatment in highly impacted regions to prevent end-stage liver disease and death due to undiagnosed and untreated HBVB.
The authors mention, and I would like to highlight, the ethical concerns associated with providing free tenofovir therapy to people to prevent HIV infection when people with HBV who desperately need this treatment to prevent liver cancer do not have access to it. We must focus on improving capacity to manage and treat HBV in limited resource settings in order to safely scale up implementation of tenofovir-based PrEP.
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