Reshaping the tumor microenvironment of cold soft-tissue sarcomas with anti-angiogenics: a phase 2 trial of regorafenib combined with avelumab

Abstract

The majority of sarcomas are under the influence of a tumor microenvironment that dampens immune activity, resulting in resistance to monoclonal antibodies targeting immune checkpoints and reduced clinical effectiveness. Preclinical studies indicate that targeting abnormal neoangiogenesis by inhibiting vascular endothelial growth factor receptor (VEGFR) can alter the TME, thereby promoting T cell infiltration and increasing tumor immunogenicity. The REGOMUNE study, a phase II clinical trial, assessed the therapeutic combination of regorafenib, a multityrosine kinase inhibitor that targets VEGFR2 and the PD-L1 blocker avelumab, in individuals with advanced "cold" STS characterized by a lack of mature tertiary lymphoid structures (mTLS). Forty-nine mTLS-negative STS patients were enrolled, including leiomyosarcoma (45%), synovial sarcoma (18%), and other subtypes. The objective response rate was 11.0% (95% CI: 4.0% - 22.0%), with median progression-free survival and overall survival of 1.8 months (95% CI, 1.7-3.5 months) and 15.1 months, respectively. Frequent adverse events included grade 1 or 2 palmar-plantar erythrodysesthesia, fatigue, and diarrhea. On-treatment multiplex immunofluorescence analysis revealed significant increases in CD8 + T cell and B cell infiltration and PD1 expression on immune cells. Plasma analysis indicated significant upregulation of soluble PD-L1 (sPD-L1) levels and tryptophan consumption. Overall, these results indicate that anti-angiogenic therapy modulates the tumor microenvironment in patients with cold STS and highlight the need for complementary strategies to enhance the functional activity of immune cells in this particular setting. Clinical trial registration number: NCT03475953.

Fig. 1

Flow chart of the REGOMUNE

Fig. 2

Efficacy of the combination Regorafenib-Avelumab in cold soft-tissue sarcoma patients. a Waterfall plot and b Spider plot of the maximum change in tumor size in patients with sarcoma treated with regorafenib plus avelumab and eligible for efficacy (n = 43). Kaplan–Meier curves of the progression-free survival (c) and overall survival (d). RECIST Response Evaluation Criteria in Solid Tumors

Fig. 3

Regorafenib-Avelumab treatment triggers an immune response in cold soft-tissue sarcoma patients. a Flow chart illustrates the strategy used to identify biomarkers linked with Regorafenib-Avelumab treatment. Plasma samples collected at baseline and Cycle2 Day1 (C2D1) were analyzed using the Olink Explore HT panel. b Volcano plot showcases the differential protein expression in sarcoma patients upon treatment. c Boxplot representation of soluble CD274 (PD-L1) protein secretion. d Network visualization of GO term enrichment in patients treated with Regorafenib-Avelumab (left) and characterization of each identified cluster by text-mining (right). e Heatmap of immune cell estimation calculated by gsva in sarcoma patients upon treatment with Regorafenib and avelumab. f Boxplot representation of CD8+ T cells and B cells estimated proportions. P values were calculated using the Wilcoxon tests

Fig. 4

Regorafenib and avelumab treatment induce B and T cells infiltration in sarcoma patients. a Illustration of 7-plex immunohistofluorescence panel. b Boxplot representations of CD8+, CD4+, CD20+ (B cells) and CD163+ (M2 macrophages) cell densities. c Illustration of treatment-induced immune infiltration in one sarcoma patient with progressive disease. d Quantification of the percentage of CD20+ cells colocalized with CD3+ cells (CD4+ or CD8+) in a radius of 10 µm. e Illustration of PD-1 expression upon treatment. f Boxplot representations of PD-1 expression in CD8+ and CD4+ T cells. All the p values were calculated using Wilcoxon tests