Immune Modulation by Abemaciclib in Head and Neck Squamous Cell Carcinoma (HNSCC). (AIM Trial)

This is a Phase II single-arm window trial to assess the clinical and biological effects of 10-21 days of neoadjuvant abemaciclib in patients with HPV-negative HNSCC who are planned for oncologic surgery, with pre-clinically informed genetic and immune biomarker correlatives. In the window-of-opportunity clinical trial, patients planned for oncologic surgery are briefly exposed to a novel cancer agent in the window between diagnostic biopsy and definitive surgery. Paired, pre- and post-surgical tumor specimens permit ex vivo analysis of target modulation in both tumor and the tumor microenvironment - providing insight into mechanism of action and paving the way for rigorous companion biomarker development. Clinical activity is assessed by quantitative change in tumor size (∆T), which is correlated to hypothesis-driven genomic and immune biomarkers of interest. Investigators hypothesize that abemaciclib will significantly reduce tumor burden as measured by ∆T. Further, investigators will test the primary biomarker hypothesis that the clinical activity of abemaciclib is associated with an increased proportion of tumors that are T-cell inflamed. Investigators will evaluate tumor-intrinsic, tumor microenvironment (TME), and microbiome biomarker hypotheses in specific genetic contexts, including tumors with specific classes of tumor protein 53 (TP53) mutations, p16 loss, and/or CCND1 amplification.