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Resistance to immune checkpoint therapy (ICT) presents a growing clinical challenge. The tumor microenvironment (TME) and its components, namely tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs), play a pivotal role in ICT resistance; however, the underlying mechanisms remain under investigation. In this study, we identify expression of TNF-Stimulated Factor 6 (TSG-6) in ICT-resistant pancreatic tumors, compared to ICT-sensitive melanoma tumors, both in mouse and human. TSG-6 is expressed by CAFs within the TME, where suppressive macrophages expressing Arg1 , Mafb , and Mrc1 , along with TSG-6 ligand Cd44 , predominate. Furthermore, TSG-6 expressing CAFs co-localize with the CD44 expressing macrophages in the TME. TSG-6 inhibition in combination with ICT improves therapy response and survival in pancreatic tumor-bearing mice by reducing macrophages expressing immunosuppressive phenotypes and increasing CD8 T cells. Overall, our findings propose TSG-6 as a therapeutic target to enhance ICT response in non-responsive tumors. Pancreatic ductal carcinoma (PDAC) is characterized by an immunosuppressive tumor microenvironment (TME) enriched in stromal cells. Here the authors show that TSG-6-positive cancer associated fibroblasts modulate myeloid cell responses and that TSG-6 targeting improves response to immune checkpoint inhibitors in preclinical PDAC models.

Immune checkpoint therapy is being tested in the neoadjuvant setting for patients with localized urothelial carcinoma 1 , 2 , with one study reporting data in cisplatin-ineligible patients who received anti-PD-L1 monotherapy 2 . The study reported that patients with bulky tumors, a known high-risk feature defined as greater than clinical T2 disease, had fewer responses, with pathological complete response rate of 17% 2 . Here we report on the first pilot combination neoadjuvant trial ( NCT02812420 ) with anti-PD-L1 (durvalumab) plus anti-CTLA-4 (tremelimumab) in cisplatin-ineligible patients, with all tumors identified as having high-risk features ( n  = 28). High-risk features were defined by bulky tumors, variant histology, lymphovascular invasion, hydronephrosis and/or high-grade upper tract disease 3 – 5 . The primary endpoint was safety and we observed 6 of 28 patients (21%) with grade ≥3 immune-related adverse events, consisting of asymptomatic laboratory abnormalities ( n  = 4), hepatitis and colitis ( n  = 2). We also observed pathological complete response of 37.5% and downstaging to pT1 or less in 58% of patients who completed surgery ( n  = 24). In summary, we provide initial safety, efficacy and biomarker data with neoadjuvant combination anti-PD-L1 plus anti-CTLA-4, which warrants further development for patients with localized urothelial carcinoma, especially cisplatin-ineligible patients with high-risk features who do not currently have an established standard-of-care neoadjuvant treatment. Neoadjuvant combination of immune checkpoint therapy in patients with cisplatin-ineligible bladder cancer achieves clinical efficacy and uncovers immune features as potential predictive biomarkers of treatment response.

Surgical removal of primary tumors reverses tumor-mediated immune suppression in pre-clinical models with metastatic disease. However, how cytoreductive surgery in the metastatic setting modulates the immune responses in patients, especially in the context of immune checkpoint therapy (ICT), is not understood. We report the first prospective, pilot, non-comparative clinical trial (NCT02210117) to evaluate the feasibility, clinical benefits, and immunologic changes of combining three different ICT-containing strategies with cytoreductive surgery or biopsy for patients with metastatic clear cell renal cell carcinoma. Primary safety endpoint of this trial has been met, with 43 patients completing cytoreductive surgery, 36 patients undergoing post-ICT biopsy, and 25 patients without either procedure due to progressive disease or toxicities or withdrawal of consent (total N  = 104). Patients receiving ICT with cytoreductive surgery or biopsy, did not experience additional ICT- or procedure-related toxicities. The median overall survival was 54.7 months for patients who received ICT plus cytoreductive surgery. Immune-monitoring studies demonstrated that cytoreductive surgery increased antigen-presenting dendritic cell population and decreased KDM6B-expressing immune-suppressive myeloid cells in the peripheral blood. This study highlighted the feasibility of combining ICT with cytoreductive surgery in a metastatic setting and demonstrated the potential enhancement of immune responses following ICT plus cytoreductive surgery. Clinical evidence suggests that debulking surgery in patients with metastatic disease could enhance response to immune checkpoint therapy. Here the authors report the results of a clinical trial of immune checkpoint inhibitors plus debulking surgery in patients with metastatic renal cell carcinoma.