Engineered NK Cells Successfully Target HIV Viral Reservoirs in Primate Study
Researchers developed a novel multiplex-engineered NK cell therapy that successfully localized to sites of SIV (the simian equivalent of HIV) replication in lymph node follicles of rhesus macaques. The therapy combined five modifications — a CAR targeting viral envelope protein, CXCR5 and CCR7 for follicular homing, IL-15 for survival, and PD-1 knockout to reduce exhaustion — addressing a key barrier to HIV cure: viral reservoirs hidden in B cell follicles that immune cells typically cannot reach. If translatable to humans, this approach could help eliminate the persistent HIV reservoirs that prevent a functional cure.
A research team published a preprint on bioRxiv describing the development and testing of multiply-engineered natural killer (NK) cells designed to seek out and destroy HIV reservoirs in lymphatic tissue. A major obstacle to curing HIV is that the virus persists in B cell follicles of lymph nodes and the spleen, compartments that cytotoxic immune cells normally cannot enter due to lack of the homing receptor CXCR5. The engineered NK cells were modified with five simultaneous alterations: a chimeric antigen receptor (CAR) targeting SIV envelope protein, overexpression of CXCR5 and transient CCR7 for follicular migration, IL-15 to support cell survival, and knockout of the inhibitory checkpoint receptor PD-1. In vitro, the cells expanded to clinically relevant numbers, migrated toward relevant chemokine signals, and released cytotoxic molecules in response to SIV-expressing target cells. In a preliminary single-animal safety study and a subsequent larger multi-animal efficacy study, infusions of approximately 1.2 × 10⁸ cells per kilogram were well tolerated, with CAR-positive NK cells detected in lymph nodes and spleen at sites of active viral replication. Critically, the CAR-positive NK cells found in lymph nodes were predominantly CCR7-positive, confirming that the combination of CCR7 and CXCR5 is important for trafficking to follicular reservoirs. The authors describe this as the first demonstration of this level of engineering complexity in NK cells, and note that further optimization will be needed before clinical translation.
What's missing
As a preprint, this study has not yet undergone formal peer review. The larger primate study does not report viral load outcomes or quantitative reductions in reservoir size, leaving the functional antiviral efficacy of the therapy unclear. Long-term persistence and potential off-target toxicity of the multiply-engineered cells beyond the observation window are also not addressed.
What different sources said
- bioRxivCenter
Multiplex engineering of rhesus macaque NK cells enhances homing to sites of HIV replication in B cell follicles.
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