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We aimed to determine the activity of the anti-VEGF receptor tyrosine-kinase inhibitor, pazopanib, combined with the anti-PD-L1 inhibitor, durvalumab, in soft tissue sarcoma (STS). Further, we performed molecular characterisation with whole exome and transcriptomic sequencing to identify the determinants of response. In this single-arm, phase 2 trial (NCT#03798106), we enrolled patients with metastatic and/or recurrent STS who had received up to two previous lines of systemic anticancer therapy and had at least one measurable lesion. Treatment consisted of pazopanib 800 mg orally, administered once a day, continuously, and durvalumab 1500 mg administered via intravenous infusion once every 3 weeks. The primary endpoint was the overall response rate. Between September 2019 and October 2020, fourteen (30.5%) of the 46 evaluable patients showed an objective response, including in alveolar soft-part sarcoma, angiosarcoma, undifferentiated pleomorphic sarcoma, and desmoplastic small round cell tumour. During a median follow-up period of 18.4 months, the median progression-free survival (PFS) was 7.7 months (95% confidence interval: 5.7-10.4). The common treatment-related adverse events of grades 3-4 included neutropenia (n = 9), elevated aspartate aminotransferase (n = 7) and alanine aminotransferase (n = 5) levels, and thrombocytopenia (n = 4). In the exploratory analysis, the B lineage signature was a significant key determinant of overall response (P=0.014). In situ analysis also showed that tumours with high CD20+ B cell infiltration and vessel density had a longer PFS than those with low B cell infiltration and vessel density (P=6.5 × 10−4) as well as better response (50% vs 12%, P=0.019). In conclusion, durvalumab combined with pazopanib demonstrated promising efficacy in an unselected STS cohort, with a manageable toxicity profile. Our findings provide insights into combined high B cell infiltration and vessel density as potentially relevant biomarkers for the selection of patients who may benefit to a greater extent from PD-L1 blockade and VEGF inhibitor combination. Citation Format: Hee Jin Cho, Kum-Hee Yun, Su-Jin Shin, Young Han Lee, Seung Hyun Kim, Wooyeol Baek, Yoon Dae Han, Sang Kyum Kim, JooHee Lee, Iksung Cho, Heounjeong Go, Jiwon Ko, Inkyung Jung, Min Kyung Jeon, Hyang Joo Ryu, Sun Young Rha, Hyo Song Kim, Hyun Jung Jun. Comprehensive molecular characterization of clinical response to durvalumab plus pazopanib combination in patients with advanced soft tissue sarcomas: A phase 2 clinical trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT038.

Introduction: Desmoid tumor is a rare aggressive tumor where there is no satisfying systemic treatment. Previous studies showed increased expression of transforming growth factor-β (TGF-β) in the desmoid tumor. Here, we analyzed genomic and transcriptomic data of tumor samples from patients with desmoid tumor to evaluate therapeutic applicability of inhibition of TGF-β response. Methods: We collected pre-treatment desmoid tumor samples from 31 patients in Yonsei cancer center, (YCC)-desmoid cohort and performed targeted next-generation sequencing and whole RNA sequencing. To compare the data with other cancer types, we used whole exome sequencing and whole RNA sequencing data from sarcoma patients from Yonsei Cancer Center (YCC-sarcoma cohort, n = 17 and n =53, respectively) and The Cancer Genome Atlas (TCGA, n = 9,235). Transcriptomic data was normalized throughout the three cohorts to reduce batch effect. To evaluate the enrichment of TGF-β responsive signature (TBRS) in tumor and microenvironment, we calculated the mean expression values of fibroblast-TBRS (F-TBRS) from previous study. Results: In the two sarcoma cohorts (YCC-desmoid and YCC-sarcoma cohorts), desmoid tumor samples had the highest F-TBRS score among the various types of sarcoma. When compared with other cancer types in TCGA, desmoid tumor samples showed the higher F-TBRS than all other cancer types except for pancreatic adenocarcinoma. In the desmoid tumor samples, CTNNB1, GNAQ, and APC mutations were the top 3 frequent mutations (23, 19, and 2 samples, respectively). In the merged two sarcoma cohorts, CTNNB1/APC mutation and GNAQ mutation were both associated with higher enrichment in F-TBRS (p < 0.001, respectively). Conclusion: Desmoid tumors are enriched with expression of genes associated with TGF-β response of fibroblast compared with other cancer types including other sarcomas. In addition, CTNNB1, APC and GNAQ mutations were associated with higher enrichment in TBRS. Therapeutic intervention to decrease the TGF-β response of fibroblast by using TGF-β receptor inhibitor may show clinical benefit in patients with desmoid tumors. Citation Format: Changhee Park, Kum-Hee Yun, Sanghoon Song, Jin Kyung Lee, Jiyeon Ryu, Bitna Oh, Sunjin Hwang, Ki Baik Hahm, Seung-Jin Kim, Seung Hyun Kim, Chan-Young Ock, Hyo-Song Kim. Genomic and transcriptomic analyses of desmoid tumor reveals enrichment of transforming growth factor beta responsive signature [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2250.