Degradation-Controlled Synchronization of HIF-2α and MEK Inhibition Using Self-Sealed Porous Silicon Nanoparticles to Reprogram Tumor Immunogenicity.

Abstract

Biomaterial-mediated control of drug release kinetics enables modulation of intracellular signaling dynamics beyond simple payload delivery. Here, we build on a biodegradable, magnesium silicate self-sealed porous silicon nanoparticle (PSiNP) platform to achieve temporally coordinated dual inhibition of hypoxia-inducible factor-2α (HIF-2α) and mitogen-activated protein kinase (MEK) defined as overlapping, prolonged intracellular exposure of both agents through co-administration of two independently loaded PSiNP populations, rather than identical release rates from a single shared carrier. Combination therapies targeting these pathways are often limited by asynchronous drug decay and adaptive signaling recovery. In contrast, degradation-governed release from PSiNPs sustained the availability of belzutifan and trametinib in aqueous physiological medium for more than 10 days supporting prolonged intracellular drug exposure when combined with the established cellular internalization of this carrier system. The sustained-release behavior of the PSiNP platform is expected to prolong the biological activity of belzutifan and trametinib relative to free-drug administration, thereby supporting sustained functional inhibition of HIF-2α- and MAPK/ERK-associated pathways. In MCPyV-negative Merkel cell carcinoma models, synchronized dual inhibition enhanced cytotoxicity relative to free drug combinations and was accompanied by immunogenic remodeling, including increased calreticulin exposure and reduced PD-L1 expression. Independent release kinetics of each payload were preserved during co-delivery, supporting the robustness of the dual system. These findings identify degradation-controlled temporal coordination of pathway inhibition as a critical determinant of tumor cell fate and establish release synchronization as a key design parameter for biomaterial-enabled combination therapies. STATEMENT OF SIGNIFICANCE: Combination therapies using small-molecule inhibitors are often limited by rapid drug degradation and asynchronous intracellular target suppression, reducing the durability of therapeutic responses. In this study, we developed a biodegradable self-sealed porous silicon nanoparticle platform that enables degradation-controlled temporal synchronization of HIF-2α and MEK inhibition through sustained intracellular drug availability. By independently loading belzutifan and trametinib into separate porous silicon nanoparticle populations, the system preserves drug-specific release behavior while maintaining overlapping multi-day pathway suppression. Sustained dual inhibition enhanced cytotoxicity and promoted immunogenic remodeling in MCPyV-negative Merkel cell carcinoma models, including increased calreticulin exposure and reduced PD-L1 expression. These findings identify release synchronization as a critical biomaterial design parameter for combination cancer therapy.