Response to Pembrolizumab in Advanced Anal Squamous Cell Carcinoma With High TMB and PD-L1 and PD-L2 Amplification

Abstract

We report the case of a 44-year-old female with a prior diagnosis of Sjögren's syndrome who was treated for metastatic anal squamous cell carcinoma with second-line pembrolizumab and has achieved a sustained partial response after a follow-up of 13 months. Comprehensive genomic profiling was remarkable for PD-L1 and PD-L2 amplification and a high tumor mutational burden (19 mutations per megabase). To the best of our knowledge, we present the first report to correlate PD-L1 and PD-L2 amplification with good outcomes of immune checkpoint inhibition in metastatic anal squamous cell carcinoma.