Pembrolizumab as monotherapy in locally advanced cutaneous squamous cell carcinoma

Introduction: Outcomes for patients with advanced cutaneous squamous cell carcinoma (cSCC) are poor, however recent approvals in programmed death-1 (PD-1) checkpoint inhibition have shown promise. Prior systemic treatments in this patient population included chemotherapy and anti-EGFR directed therapies, with limited long-term benefit. Studies investigating cemiplimab and pembrolizumab have recently revealed significant responses with many cases of sustained benefit in both locally advanced and recurrent and/or metastatic disease. While these treatments have shown improvement in outcomes, there are continued areas of need. Areas covered: This review focuses on clinical evidence for PD-1 directed checkpoint inhibition in advanced cSCC. Excluded populations and new approaches involving immunotherapy are discussed. Expert opinion: Immune checkpoint inhibition in advanced cSCC has shown impressive benefit. The clinical trials for both cemiplimab and pembrolizumab demonstrate similar responses and outcomes. Biomarkers for predicting response are an area of need. In addition, these trials excluded immunosuppressed patients due to hematological malignancies or prior organ transplant, which are populations with significantly increased risk of cSCC. Finally, a variety of novel approaches using checkpoint inhibition in cSCC are being investigated, with some encouraging preliminary results.