Long-acting IL-2 release from pressure-fused biomineral tablets promotes antitumor immune response

Long-acting controlled drug release formulations are highly desired for potentiating efficacy and reducing administration frequency. Here we present a kinetically controllable long-term interleukin-2 (IL-2) release platform by the fusion and boundary elimination of calcium carbonate and calcium phosphate amorphous phases. Unlike mixtures, a group of hybrid biominerals with the chemical formula Ca(CO₃)_x(PO₄)_2(1-x)/3 (CaCPs, 0 < x < 1) was fabricated under high pressure (2 GPa), and the CaCPs showed crystallization-driven release behaviors to optimize the in vivo fate of IL-2. Ca(CO₃)_1/2(PO₄)_1/3 dynamically remodeled immunosuppressive tumor microenvironments, preferentially activated cytotoxic and memory T cells by improving IL-2 redistribution and achieved weeks-long IL-2 retention in tumors with high tolerance and biosafety. In a melanoma model in female mice, Ca(CO₃)_1/2(PO₄)_1/3 revealed superior antitumor effects to inhibit local tumor recurrence, hinder the growth of distant untreated tumors and maintain long-term T cell responses against the rechallenged metastatic tumors.