CAR Therapies Could Offer New HBV, HIV Treatments

Chimeric antigen receptor (CAR) T-cell and natural killer (CAR-NK) cell therapies are emerging as promising strategies for treating chronic viral infections such as hepatitis B virus (HBV) and human immunodeficiency virus (HIV). These virus-directed immunotherapies aim to specifically target and eliminate virally infected cells, offering potential pathways toward functional cures where current antiviral therapies often require lifelong administration.

How Virus-Directed CAR Therapies Work

CAR therapies involve engineering a patient’s own immune cells—T cells or natural killer (NK) cells—to express chimeric antigen receptors that recognize specific viral antigens. Once infused back into the patient, these engineered cells can seek out and destroy cells harboring the virus. Unlike conventional antiretrovirals or nucleos(t)ide analogues that suppress viral replication, CAR approaches directly attack the viral reservoir, a major barrier to cure in both HIV and HBV infections.

Preclinical studies have demonstrated significant antiviral activity. In HIV models, CAR-T cells targeting epitopes such as gp120 have shown marked reductions in viral load, measured by decreases in HIV p24 antigen levels. Similarly, HBV-directed CAR-T cells have been associated with declines in hepatitis B surface antigen (HBsAg) and HBV DNA in experimental systems.

Evidence from Preclinical and Early Clinical Studies

A systematic review of preclinical and early clinical evidence published in March 2026 analyzed 43 studies, including 21 in vitro, 14 in vivo, and 8 clinical trials. The findings indicated:

• Preclinical HIV CAR-T models demonstrated a pooled standardized mean difference (SMD) of −1.15 in reducing HIV p24 antigen levels (95% CI: −1.50 to −0.80), indicating a significant antiviral effect.
• HBV-directed engineered T-cell studies showed an SMD of −1.30 for decreasing HBsAg and HBV DNA levels (95% CI: −1.70 to −0.90), reflecting a substantial reduction in viral markers.

These results suggest that virus-directed CAR lymphocytes can achieve meaningful suppression of viral antigens and nucleic acids in controlled settings.

Challenges and Considerations

Despite encouraging preclinical data, several challenges remain before CAR therapies can be widely adopted for HIV or HBV:

• Safety: Risks such as cytokine release syndrome (CRS), neurotoxicity, and off-target effects require careful monitoring, especially in chronic infection settings where immune activation must be balanced.
• Persistence: The long-term engraftment and functionality of infused CAR cells are critical for sustained viral control but remain difficult to predict.
• Viral Escape: Viruses like HIV and HBV can mutate to evade immune recognition, necessitating multi-targeted CAR designs or combination strategies.
• Manufacturing and Access: The personalized nature of CAR therapy poses logistical and cost barriers that must be addressed for broader applicability, particularly in low- and middle-income countries where HBV and HIV burdens are highest.

Ongoing Research and Future Directions

Current research focuses on improving CAR design, including the use of CAR-NK cells which may offer improved safety profiles, and developing armored CARs equipped with cytokine secretion or checkpoint blockade resistance. Clinical trials are underway to evaluate dosing regimens, lymphodepletion protocols, and combinations with broadly neutralizing antibodies or therapeutic vaccines.

Efforts are also directed toward creating universal, off-the-shelf CAR products to simplify manufacturing and reduce costs. Researchers are exploring gene-editing techniques to enhance CAR cell durability and resistance to viral inhibition.

Key Takeaways

• Virus-directed CAR-T and CAR-NK therapies demonstrate preclinical efficacy in reducing HIV p24 and HBV DNA/HBsAg levels.
• Early clinical evidence supports further investigation, though larger trials are needed to establish safety and long-term outcomes.
• Challenges include managing treatment-related toxicity, preventing viral escape, and improving accessibility.
• Ongoing innovations in CAR design, manufacturing, and combination approaches aim to overcome current limitations.

While CAR therapies are not yet standard treatment for HIV or HBV, they represent a cutting-edge immunotherapeutic approach with the potential to transform how chronic viral infections are managed. Continued research and clinical development will determine whether these engineered cell therapies can achieve durable remission or functional cure in patients living with HIV or HBV.