Results of an Integrated Phase I/II Prospective Clinical Trial (NEXIS) for Neoadjuvant Anti-PD-L1 (Durvalumab) and Anti-CTLA-4 (Tremelimumab) With Radiation for High-Risk Soft-Tissue Sarcoma of the Trunk and Extremities

Background The current management of large, high-grade soft tissue sarcoma (STS) of the trunk and extremities includes radiation and surgical resection. The initial use of chemotherapy and targeted therapy are controversial and although most patients present with localized disease, many eventually develop incurable metastases. The results and analysis of the safety and antitumor activity of combined checkpoint inhibitor immunotherapy with neoadjuvant radiation for high-risk primary STS are presented here. Methods This was an integrated phase I/II prospective single-arm trial (Nutrition and Exercise in Critical Illness Trial (NEXIS) trial). Eligible patients were age ≥18 years with histologically confirmed intermediate or high-grade STS of the trunk or extremity ≥5 cm diameter and were Eastern Cooperative Oncology Group performance status 0-1. The treatment algorithm included neoadjuvant anti-PD-L1 (Durvalumab) and anti-CTLA-4 (Tremelimumab) for three cycles of four weeks/cycle along with external beam radiation for five weeks, followed by wide surgical resection, and adjuvant Durvalumab monotherapy for four cycles. High-grade toxicity was continually assessed for the first 12 patients in phase I and the primary endpoint for phase II was an excellent histological response (grade 0 or 1 score on a semi-quantitative assessment for tumor regression). This study was registered with ClinicalTrials.gov, number NCT03116529. Findings Between October 2017 and November 2021, 23 patients were enrolled. Five patients had progression of distant disease during neoadjuvant treatment and withdrew from the study before surgery. A total of 18 patients who completed at least the neoadjuvant immunotherapy, radiation and surgery were included for analysis. The most common tumor was undifferentiated pleomorphic sarcoma (n=9, 50%). The occurrence of any adverse event (AE) was recorded in 16 (88.9%) patients, and 3 (16.7%) patients had a serious AE. Eight out of 18 patients (44.4%) had disease-free survival at a median of 39.7 months. Four out of 18 patients (22.2%) were alive-with-disease at a median of 37.1 months from diagnosis of distant metastasis, and six out of 18 (33.3%) died of disease at a median of 20.8 months from diagnosis of distant metastasis. Local recurrence occurred in two patients (11.1%) and was concomitant with distant disease in each case. Based on Response Evaluation Criteria in Solid Tumors v1.1, a partial response was noted in five (27.8%) cases, stable disease in 10 (55.6%) cases, and progressive disease in three (16.7%) cases. Histological semiquantitative analysis revealed a "good" response in eight (44.4%) patients, a "moderate" response in four (22.2%) patients, and a "poor" response in six (33.3%) patients. The mean patient-reported outcome measures regarding fatigue, physical function, or physical interference demonstrated no significant differences between various timepoints before, during, or after treatment. Conclusion Neoadjuvant combined immunotherapy and radiation for high-risk STS was relatively well-tolerated. The histological, radiologic, and clinical outcome data in this novel trial were relatively similar to historical literature for non-immunotherapy treatment regimens.