Photosensitizer-loaded gold nanocages for immunogenic phototherapy of aggressive melanoma

Malignant melanoma remains the life-threatening form of skin cancer with high mortality and poor prognosis. Thus, an ideal melanoma therapeutic strategy is of immediate importance which can remove the primary tumor, as well as inhibit the metastasis and recurrence. Here, we report the fabrication of adjuvant monophosphoryl lipid A (MPLA) lipid bilayer-enveloped and photosensitizer indocyanine green (ICG)-loaded gold nanocages (MLI-AuNCs) for immunogenic phototherapy of aggressive melanoma. Hollow porous AuNCs are used as carriers to deliver MPLA and ICG, and protect ICG from photodegradation. Both AuNCs and ICG absorb near infrared (NIR) light and can be applied in controllable NIR-triggered photothermal and photodynamic combination therapy (PTT/PDT) of melanoma. MLI-AuNCs coated by thermosensitive lipid bilayer exhibit uniform size, good biocompatibility and bioavailability with prominent tumor accumulation, which further improve the PTT/PDT efficacy. MLI-AuNCs under NIR irradiation not only destroy the primary tumor by PTT/PDT, but also elicit robust antitumor immune response with melanoma associated antigens and MPLA released in situ. The released antigens and MPLA subsequently enhance the recruitment and maturation of dendritic cells, which further activate the effector T cells to inhibit metastases and recurrence of melanoma. This immunomodulatory-boosted PTT/PDT nanoplatform provides a new opportunity for highly aggressive melanoma treatment. STATEMENT OF SIGNIFICANCE: An ideal tumor therapeutic strategy not only can remove the primary tumor, but also inhibit metastasis and recurrence. Here, we introduced a versatile nanoplatform MLI-AuNCs for immunogenic phototherapy of aggressive melanoma. Adjuvant MPLA and photosensitizer ICG can be protected and co-delivered to the tumors by thermosensitive lipid-enveloped AuNCs. MLI-AuNCs exhibited prominent tumor accumulation ability and produced the potent PTT/PDT effect to destroy the primary tumors with a single dose of NIR irradiation, as well as elicited the strong antitumor immunity to inhibit the metastasis and relapse. This study may provide a potential therapeutic vaccination strategy against advanced melanoma and other difficult-to-treat cancers.