A locally advanced colon cancer patient with Muir-Torre syndrome obtains durable response to neoadjuvant and adjuvant immunotherapy

Muir-Torre syndrome, presenting with cutaneous tumors and visceral malignancies, is a variant of Lynch syndrome. The development of immune checkpoint inhibitors provided novel effective treatment options for metastatic colorectal cancer patients with microsatellite instability and deficient mismatch repair. However, the use of immune checkpoint inhibitors in neoadjuvant and adjuvant settings for patients with locally advanced colorectal cancer remains undefined because of limited follow-ups in current studies.In the present study, we reported a 33-year-old Muri-Torre syndrome patient with stage ⅢC (c.T4N2M0) colorectal cancer and keratoacanthoma. Microsatellite instability / deficient mismatch repair, high tumor mutation burden, and MSH2 germline mutation were identified by next-generation sequencing. Pembrolizumab monotherapy was used as neoadjuvant treatment and the patient achieved a major pathological response. After surgical resection, pembrolizumab was continuously used in an adjuvant setting for 12 months. The patient remained disease-free with a durable disease-free survival for 44 months. To our knowledge, this is the first and longest follow-up study reporting pembrolizumab as a single-agent neoadjuvant therapy for locally advanced colon cancer.The results demonstrate promising performance in neoadjuvant and adjuvant settings. Further studies are needed to confirm its potential usefulness as an outcome measure in clinical practice.