A PSMA-targeted dextran-based conjugate eradicates PSMA-overexpressing prostate tumors while abolishing cabazitaxel toxicity.

BACKGROUND

High expression of prostate-specific membrane antigen (PSMA) is observed in advanced prostate cancer, supplying a promising target for precision therapeutic interventions. Despite its efficacy in metastatic castration-resistant disease, cabazitaxel (CTX) is limited by severe systemic toxicity and a narrow therapeutic index, underscoring the urgent demand for tumor-selective delivery systems.

METHODS

A novel PSMA-targeted dextran-based conjugate, Dextran-CTX-GLA-EuK, was synthesized via click chemistry by conjugating CTX, γ-linolenic acid (GLA), and a Glu-urea-Lys (EuK) PSMA-targeting ligand to bifunctionalized dextran. Critical in vitro and in vivo PSMA blocking experiments (using the PSMA inhibitor 2-PMPA) were performed to validate its targeting specificity. A thorough myelosuppression study was performed in murine models to evaluate the systemic hematological safety profile. The biodistribution profile and in vivo antitumor efficacy of the conjugate were evaluated in murine xenograft models.

RESULTS

The conjugate Dextran-CTX-GLA-EuK exhibited favorable physicochemical properties, high water solubility, and strong PSMA-binding affinity. In vitro and in vivo PSMA blocking experiments conclusively verifying its PSMA-mediated specific cellular internalization and tumor accumulation. In PSMA-overexpressing xenograft models, the conjugate demonstrated selective tumor enrichment, with intratumoral CTX levels up to 98.3-fold higher than those of parent CTX, while reducing exposure in normal tissues. Dextran-CTX-GLA-EuK exerted prominent dose-dependent tumor growth inhibition, attaining a 96.6% suppression rate at a 10 mg/kg dosage in PC-3/PSMA tumors and prolonging the survival of 22Rv1 tumor-bearing mice. Importantly, comprehensive myelosuppression assays revealed that the conjugate only induced a transient reduction in white blood cell and neutrophil counts (which rapidly recovered to baseline) without impairing bone marrow hematopoietic function; unlike CTX, the conjugate did not cause significant weight loss, organ toxicity, or hematological abnormalities in tumor-bearing mice.

CONCLUSIONS

These findings demonstrate that Dextran-CTX-GLA-EuK synergizes active targeting with dextran-based delivery, enhancing antitumor efficacy while abolishing dose-limiting toxicities. This strategy offers a clinically translatable approach for PSMA-directed therapy in prostate cancer.