A PSMA‑Targeted CAR‑T Cell Therapy with CD16A Signaling for Prostate Cancer

Adoptive transfer of chimeric antigen receptor (CAR) T cells has worked well in some blood cancers, but it has been much less effective in solid tumors like prostate cancer. One reason is the strong cytokine release and strong immune suppression in the tumor area. A new study has designed a PSMA‑targeted CAR that uses CD16A, an innate immune receptor, as its only signaling part, instead of classic co‑stimulatory domains like 4‑1BB or CD28. This change may help reduce toxic side effects while still fighting the tumor.

The CAR is built from a humanized J591‑derived anti‑PSMA single‑chain variable fragment (scFv) linked to the CD16A transmembrane and intracellular domains and delivered by a lentiviral vector. Human T cells that carry this PSMA‑CD16A CAR are tested against PSMA‑positive LNCaP prostate cancer cells in a luciferase‑based killing assay. The cells show clear antigen‑dependent destruction of tumor cells, with CAR‑T cells killing much more effectively than untransduced T cells. At the same time, cytokine levels of TNF‑α, IFN‑γ, and IL‑2 remain elevated enough to support immune function but do not spike as high as in many standard CAR‑T designs. This suggests that the CAR can be powerful without driving extreme cytokine release.

In mice with subcutaneous LNCaP xenografts, treatment with PSMA‑CD16A CAR‑T cells leads to strong tumor control and longer survival. Median overall survival is 97 days in the CAR‑T group, compared with 71 ± 8 days in mice that receive untransduced T cells, a 36.6% increase. Three out of five CAR‑T‑treated mice survive to the end of the observation period, with visible tumor shrinkage and complete response. Survival is ultimately limited by xeno‑reactive graft‑versus‑host disease in this NSG mouse model, meaning the animals die from host immune problems rather than from the tumor itself. Still, the data show that CD16A‑only signaling can support strong antitumor activity against prostate cancer.

By using CD16A alone, the design avoids the intense activation signals that often cause cytokine storms while keeping enough activity to kill tumor cells. This is especially important for prostate cancer, where PSMA is a well‑known target but is also present at low levels in some normal tissues. A milder cytokine profile could make future PSMA‑CAR‑T treatments safer and easier to dose, potentially allowing repeated or higher‑dose therapy. In the larger picture of prostate cancer immunotherapy, this PSMA‑CD16A CAR‑T adds a new idea to existing PSMA‑targeted approaches, which already include standard CAR‑T cells, radioligands, and bispecific antibodies. Current clinical trials with PSMA‑CAR‑T in metastatic castration‑resistant prostate cancer show PSA declines and disease stabilization, but complete responses are rare and long‑term persistence is still a big hurdle.

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