Complete pathologic response of metastatic cutaneous squamous cell carcinoma and allograft rejection after treatment with combination immune checkpoint blockade

cSCC: cutaneous squamous cell carcinoma DICB: dual immune checkpoint blockade ICB: immune checkpoint blockade ipi/nivo: ipilimumab and nivolumab mcSCC: metastatic cSCC INTRODUCTION Roughly 1.1 million cases of cutaneous squamous cell carcinoma (cSCC) occur annually. Although most cases can be cured with local therapy, up to 8,000 deaths from metastatic cSCC (mcSCC) occur each year, a number similar to that of melanoma. With no US Food and Drug Administrationeapproved options available for mcSCC, common approaches include platinumbased chemotherapy and off-label cetuximab. These strategies lack durability, and overall survival for mcSCC is only 10.9 months. Clinical responses in mcSCC have recently been reported with the use of PD-1 antibodies, pembrolizumab and nivolumab. Here we report a complete pathologic response after 4 cycles of nivolumab and the antieCTLA-4 antibody, ipilimumab, in a patient with mcSCC.