91P Single-center experience on immune checkpoint inhibitors treatment in advanced and metastatic sarcoma

Soft tissue (STS) and bone sarcomas are a heterogeneous group of diseases, with over 150 subtypes, proving a major challenge in enrollment in prospective studies. The overall survival for metastatic sarcoma is dismal around 15%. In the era of immunotherapeutic strategies and next generation sequencing (NGS), much research is ongoing to identify optimal treatments. Our single center, retrospective analyze, aims to evaluate the efficacy of immune checkpoint inhibitors (ICIs) treated patients with advanced or metastatic sarcoma. Patients with advanced or metastatic sarcomas, ECOG 0-2, treated between February 2020 and December 2023 at Sarcoma Center of University Hospital of Lausanne were analyzed retrospectively. Patients had been prescribed off-label ICIs in monotherapy or in combination with TKIs or chemotherapy. Fifteen patients with soft tissue (STS, N = 15) and two bone sarcoma (N = 2), received IV nivolumab 3 mg/kg every 2 weeks, pembrolizumab 200 mg every 3 weeks or ipilimumab 1mg/kg every 6 weeks in monotherapy or in combination with TKIs or chemotherapy. Median age was 55 (33–79), female: male ratio was 7:10. All patients underwent NGS. Four patients had variable PD-1 expression, none had high microsatellite instability, two patients expressed high tumor mutation burden (TMB). One patient with metastatic angiosarcoma received double ICIs (nivolumab plus ipilimumab), two patients received ICI and chemotherapy, five patients received TKIs and nine patients received monotherapy. Clinical benefit (response + stability) was observed in 58% of the evaluable patients, with six partial responses (three ongoing treatment) and four patients with stable disease; 7 patients had progression of disease. Grade 3–4 toxicity occurred in one patient (colitis). We describe a cohort of 17 sarcoma patients treated with ICIs with or without TKIs or chemotherapy. We found clinical benefit within 58% of the treated patients. For most sarcomas the right combination of immune checkpoint inhibition is yet to be found. The need of prospective phase II/III randomized studies of ICIs alone or in combination, as well as real world data collection, are needed to better understand the real value of ICIs approach in sarcoma patients.