David Silva Moura

Supplementary Figure S1. Kaplan–Meier survival analyses. A) progression-free survival (PFS) and B) overall survival (OS).

Supplementary Table S2. Analysis of prognostic factors related with better clinical response.

Supplementary Figure S2. Variation of HMGB1 protein levels between samples collected after treatment (week 6) and before treatment (baseline).

Supplementary Table S3. Univariate Analysis of Different Potential Prognostic Factors on PFS and OS.

Supplementary Table S1. Representativeness of Study Participants

Supplementary Figure S1. Correlation between the 7-gene-based signature score and best response. The test of Mann-Whitney was used for the correlation analyses.

Supplementary Table S3. Patient demographics of patients enrolled in the GEIS-32 clinical trial.

Supplementary Table S1. MAXSTAT cut-off values for each gene of SIGNIOS signature.

Purpose:Immune checkpoint inhibitors (ICI) have transformed cancer therapy, but their efficacy in sarcomas remains limited. A seven-gene predictive signature (CD86, CHI3L1, CXCL10, CXCL9, LAG3, NR4A1, and VCAM1) was previously identified as a biomarker for response to combined antiangiogenic and PD-1 inhibitor therapy in soft-tissue sarcomas. This study aimed to externally validate the predictive utility of this signature [SIGNature for immuno-oncology PD-1 inhibitors in sarcoma (SIGNIOS)] in an independent cohort of patients with sarcoma treated with ICIs.Experimental Design:Using RNA sequencing data from pretreatment tumor samples from the SARC028 phase II trial (pembrolizumab for advanced sarcomas) and the GEIS-32 phase II trial (pazopanib in advanced solitary fibrous tumor), we calculated the SIGNIOS score. Patients were stratified into low (score 0–4) and high (score 5–7) risk groups.Results:The SARC028 validation cohort comprised 31 patients, with a median age of 33 years, and 45.2% were female. The most common histologic subtypes included osteosarcoma (25.8%) and Ewing sarcoma (19.4%). The seven-gene signature significantly stratified patients into groups with significantly different progression-free survival (PFS): Those with scores of 0 to 4 had a median PFS of 49 days, whereas those with scores of 5 to 7 had a median PFS of 170 days [HR = 0.71 (95% confidence interval, 0.55–0.91), P = 0.007].Conclusions:This external validation confirms the seven-gene signature as a potential biomarker for predicting ICI efficacy in advanced sarcomas. Prospective studies are needed to determine the prognostic versus predictive value of SIGNIOS, refine its use across sarcoma subtypes, and explore its applicability in other tumor types.

Supplementary Table S2 – Univariate survival analysis of the genes included in the 7-gene-based signature score.