The efficacy of immune checkpoint inhibitors as a part of multimodality treatment in soft tissue and bone sarcoma in an academic community setting.

e23564 Background: Prior studies have shown response to immune checkpoint inhibitors (ICI) in a variety of sarcoma subtypes, however, much is still unknown about ICI use in specific sarcoma subtypes due to disease rarity. Patients (pts) are often treated with these agents as part of clinical trials, and real world data in the community setting is lacking. The aim of this study is to report real world efficacy and safety of ICI in sarcoma either alone or with radiation (RT) and/or surgery. Methods: A retrospective cohort review was conducted to identify pts with soft tissue and bone sarcoma who were administered ICI at Kellogg Cancer Center at NorthShore University HealthSystem/Endeavor Health. Pts who received ICI as part of a clinical trial were excluded. Results: A total of 29 pts receiving ICI were identified. Pts had a median of 1 prior systemic therapy. ICI included pembrolizumab (n = 23), nivolumab (n = 5), and ipilimumab/nivolumab (n = 1). Treatment was discontinued in 28 pts due to disease progression (n = 18), toxicities (n = 3), death (n = 2), and maximal response (n = 5). One patient is still undergoing treatment. Median progression-free survival (PFS) was 4.9 months. Median overall survival (OS) was 14 months. Overall response rate (ORR) is 31%. Median duration of response was not reached (44+ months). Complete response (CR) (n = 5) reported in 3 pts with undifferentiated pleomorphic sarcoma (UPS), 1 pt with SMARCA4 deficient undifferentiated sarcoma, and 1 pt with dedifferentiated chondrosarcoma. Partial response (PR) (n = 4) reported in 1 pt with UPS, 1 pt with dedifferentiated liposarcoma, 1 pt with high grade spindle sarcoma of bone, and 1 pt with malignant peripheral nerve sheath tumor. Of those pts with a CR, 2 patients received only pembrolizumab, 1 pt was administered concomitant RT, and 2 pts had administered concomitant surgery. Of the pts who had PR, 3 were also treated with concomitant RT. Grade 3 immune related adverse effects were reported in 5 of the 29 patients. Of these patients, 2 had documented CR and 3 documented PR. Conclusions: This study expands on the real world efficacy of ICI in a variety of sarcoma subtypes. CR and PR rates in this setting were high, and responses were durable, although selection bias for treatment may have played a role. This data supports the treatment of metastatic sarcoma with ICI, especially with concomitant RT and surgery, in a variety of subtypes.