Dual CDK and MEK Inhibition potentiates CD8+ T cell-mediated antitumor immunity by inducing pyroptotic cell death in high-mutational head and neck cancer

Abstract Background HPV-negative (−) head and neck squamous cell carcinoma (HNSCC) is a highly heterogeneous cancer characterized by high mutational burden, an immunosuppressive microenvironment, and poor response to standard therapies. These features highlight the urgent need for novel and more effective treatment strategies. Methods Drug sensitivity prediction was performed using integrated datasets from TCGA, GDSC, and CCLE. To assess the therapeutic potential and underlying mechanisms of combining the CDK inhibitor AZD5438 with the MEK1/2 inhibitor PD0325901, we employed a comprehensive panel of HNSCC models, including established cell lines, orthotopic mouse tumor models, and patient-derived organoids (PDOs). Lipid nanoparticles (LNPs) were engineered to co-deliver both agents into the same cancer cell populations. The tumor secretome was profiled using biotinylation coupled with liquid chromatography-mass spectrometry (LC-MS). Molecular alterations were examined by immunofluorescence, immunohistochemistry, ELISA, flow cytometry, and Western blot. Results Our bioinformatics analysis identified AZD5438 and PD0325901 as two of thirteen candidate drugs whose sensitivity is consistently associated with the five most frequently mutated genes in HPV (−) HNSCC. Notably, among these candidates, AZD5438 and PD0325901 exhibited the lowest correlation in their sensitivity profiles, suggesting complementary mechanisms of action. In experimental models, the combination of AZD5438 and PD0325901 not only outperformed either monotherapy in suppressing tumor growth but also augmented CD8⁺ T cell-mediated antitumor immunity by promoting caspase-8/gasdermin E-dependent pyroptosis. Furthermore, in both orthotopic tumor-bearing mice and PDOs, the LNP-encapsulated drug combination produced significantly greater therapeutic efficacy compared with the free drug formulation. Conclusions Our findings indicate that the combination of AZD5438 and PD0325901 holds therapeutic potential for the treatment of HPV (−) HNSCC, particularly in tumors with a high mutational burden. By targeting complementary pathways, this combination may improve treatment outcomes in this aggressive cancer subtype.