Multistage responsive microneedle delivery system loaded oncolytic virus for topical therapy of melanoma.

Melanoma, the most aggressive form of skin cancer, remains a formidable therapeutic challenge. While oncolytic viruses (OVs) exhibit promising antitumor potential, their efficacy is often limited by insufficient intratumoral viral replication, poor tissue penetration, and the immunosuppressive tumor microenvironment (TME). Herein, a multistage microneedle (MN-OJ) system designed to amplify both local oncolysis and systemic antitumor immunity mediated by oncolytic adenovirus (OA) in melanoma. The dissolvable MN base facilitates rapid OA delivery, inducing tumor cell lysis and subsequent release of tumor-associated antigens to prime T-cell responses. Concurrently, the degradable MN tip enables sustained release of JQ1, which enhances OA replication, modulates lactic acid levels and PD-L1 expression, thereby reprogramming the immunosuppressive TME to promote T-cell infiltration and cytotoxicity. In murine models, MN-OJ demonstrated potent inhibition of both primary and distal tumors, without systemic toxicity. This innovative platform combines immediate tumor destruction with sustained immune modulation, offering a promising clinical approach for melanoma therapy.