Use of Neoadjuvant Immunotherapy in Malignant Peritoneal Mesothelioma as a Bridge to Surgical Intervention: A Case Report.

BACKGROUND Malignant peritoneal mesothelioma (MPM) is a rare subtype of malignant mesothelioma (MM) that arises from mesothelial/serosal surfaces of the peritoneal lining and carries a poor prognosis. Given the rarity of this disease, many expert groups such as the Peritoneal Surface Oncology Group International (PSOGI) and the National Comprehensive Cancer Network (NCCN) have developed recommendations to guide the optimal treatment for MPM. Currently, the standard of care for resectable MPM is a combination of cytoreductive surgery (CRS) followed by hyperthermic intraperitoneal chemotherapy (HIPEC). There are no clear guidelines for treatment of inoperable malignant mesothelioma, but several studies have demonstrated a benefit of incorporating immunotherapy in the treatment plan. CASE REPORT We present a case of a 63-year-old woman who sought medical attention for several months of persistent vague abdominal discomfort, weight loss, and night sweats. Laboratory workup and diagnostic imaging led to the diagnosis of borderline/unresectable MPM. A multidisciplinary tumor board discussion based on the published literature and guidelines on malignant mesothelioma (MM) was undertaken, and the decision was made to treat the patient with nivolumab-ipilimumab in the perioperative period. The patient had a positive clinical response allowing for subsequent CRS and HIPEC. She remains disease free 30 months following her surgery, with the intention to continue the immunotherapy. CONCLUSIONS This case report contributes to the current literature demonstrating a potential role for perioperative immunotherapy in the treatment of aggressive subtype or borderline resectable/unresectable MPM and a bridge to consolidative CRS/HIPEC.