Response to Abemaciclib and Immunotherapy Rechallenge with Nivolumab and Ipilimumab in a Heavily Pretreated TMB-H Metastatic Squamous Cell Lung Cancer with CDKN2A Mutation, PIK3CA Amplification and TPS 80%: A Case Report

Inactivation of the cyclin-dependent kinase inhibitor 2A (CDKN2A) gene is considerably more frequent in squamous cell lung cancer (SqCLC) than in other subtypes of lung cancer and may be a promising target for this histology. Here, we present the course of diagnosis and treatment of a patient with advanced SqCLC, harboring not only CDKN2A mutation but also PIK3CA amplification, Tumor Mutational Burden-High (>10 mutations/megabase), and a Tumor Proportion Score of 80%. After disease progression on multiple lines of chemotherapy and immunotherapy, he responded favorably to treatment with the CDK4/6i Abemaciclib and later achieved a durable partial response to immunotherapy rechallenge with a combination of anti-PD-1 and anti-CTLA-4, nivolumab, and ipilimumab.