Pancreatic ductal adenocarcinoma (PDAC) has few effective treatments. Immunotherapy, an attractive alternative strategy, remains challenging with the lack of knowledge on the tumor-infiltrating lymphocyte (TIL) landscape in PDAC. To generate a reference of T-cell subpopulations, we profiled 80,000 T cells from 57 PDAC samples, 22 uninvolved/normal samples, and cultured TIL using single-cell transcriptomic and T-cell receptor analysis. These data revealed 20 cell states and heterogeneous distributions of TIL populations. The CD8+ TIL contained a putative transitional GZMK+ population based on T-cell receptor clonotype sharing, and cell-state trajectory analysis showed similarity to a GZMB+PRF1+ cytotoxic and a CXCL13+ dysfunctional population. Statistical analysis suggested that certain TIL states, such as dysfunctional and inhibitory populations, often occurred together. Finally, analysis of cultured TIL revealed that high-frequency clones from effector populations were preferentially expanded. These data provide a framework for understanding the PDAC TIL landscape for future TIL use in immunotherapy for PDAC. Significance: To improve the efficacy of immunotherapy in PDAC, there is a great need to understand the PDAC TIL landscape. This study represents a reference of PDAC TIL subpopulations and their relationships and provides a foundation upon which to base future immunotherapeutic efforts. This article is highlighted in the In This Issue feature, p. 2221

PURPOSE: Previous studies suggest that besides anatomy (A: resectable, borderline resectable [BR], or locally advanced [LA]) also biologic (B: carbohydrate antigen 19-9 [CA 19-9]) and conditional (C: performance status) factors should be considered when staging patients with localized pancreatic ductal adenocarcinoma (PDAC). The prognostic value of the combined ABC factors has not been quantitatively validated. METHODS: In this retrospective cohort study, we evaluated patients with localized PDAC treated with initial (modified) fluorouracil with leucovorin, irinotecan, and oxaliplatin ([m]FOLFIRINOX) at five high-volume pancreatic cancer centers in the United States and the Netherlands (2012-2019). Multivariable Cox proportional hazards analysis was used to investigate the impact of the ABC factors for overall survival (OS). RESULTS: Overall, 1,835 patients with localized PDAC were included. Tumor stage at diagnosis was potentially resectable in 346 (18.9%), BR in 531 (28.9%), and LA in 958 (52.2%) patients. The baseline CA 19-9 was >500 U/mL in 559 patients (32.5%). Performance status was ≥1 in 1,110 patients (60.7%). Independent poor prognostic factors for OS were BR disease (hazard ratio [HR], 1.26 [95% CI, 1.06 to 1.50]), LA disease (HR, 1.71 [95% CI, 1.45 to 2.02]), CA 19-9 >500 U/mL (HR, 1.36 [95% CI, 1.21 to 1.52]), and WHO performance status ≥1 (HR, 1.31 [95% CI, 1.16 to 1.47]). Patients were assigned 1 point for each poor ABC factor and 2 points for LA disease. The median OS for patients with score 0-4 was 49.7, 29.9, 22.0, 19.1, and 14.9 months with corresponding 5-year OS rates of 47.0%, 28.9%, 19.2%, 9.3%, and 4.8%, respectively. CONCLUSION: The ABC factors of tumor anatomy, CA 19-9, and performance status at diagnosis were independent prognostic factors for OS in patients with localized PDAC treated with initial (m)FOLFIRINOX. Staging of patients with localized PDAC at diagnosis should be based on anatomy, CA 19-9, and performance status.

Large pragmatic studies of patients who received 5-fluorouracil with leucovorin, irinotecan, and oxaliplatin ([m]FOLFIRINOX) as initial treatment for localized pancreatic ductal adenocarcinoma (PDAC) are lacking. This study aimed to provide realistic estimates of oncologic outcomes in these patients. This international retrospective cohort study included all consecutive patients presenting with localized PDAC who received at least 1 cycle of (m)FOLFIRINOX as initial treatment in 5 referral centers from the United States and the Netherlands (2012-2019). Primary outcome was median overall survival (OS), calculated from the date of tissue diagnosis, assessed using Kaplan-Meier estimates. Log-rank test was used to compare OS between groups. A Cox proportional hazards regression model was used to assess prognostic baseline factors for OS. All statistical tests were 2-sided. Overall, 1835 patients were included, of whom 958 (52.2%) had locally advanced (LA), 531 (28.9%) had borderline resectable (BR), and 346 (18.9%) had potentially resectable (PR) PDAC. The median number of (m)FOLFIRINOX cycles was 6 (interquartile range = 4-8). Subsequent treatment included second chemotherapy (12.9%), radiotherapy (49.0%), and resection (37.9%). The resection rate was 17.6% for LA, 53.1% for BR, and 70.5% for PR PDAC (P < .001). The margin-negative resection rate (>1 mm) was 55.2% for LA, 62.6% for BR, and 79.2% for PR PDAC (P < .001). The median OS was 18.7 months (95% confidence interval [CI] = 17.7 to 19.9 months) for LA, 23.2 months (95% CI = 21.0 to 25.7 months) for BR, and 31.2 months (95% CI = 26.2 to 36.6 months) for PR PDAC (P < .001). The median OS for 695 patients who underwent a resection was 38.3 months (95% CI = 36.1 to 42.0 months). Independent prognostic factors at baseline for worse OS were more advanced stage, worse performance status, baseline carbohydrate antigen (CA) 19-9 > 500 U/mL, and body mass index ≤18.5 kg/m². This large international cohort study provides realistic estimates of resection rates and survival in patients with LA, BR, and PR PDAC who started (m)FOLFIRINOX treatment in PDAC referral centers.

Purpose: Despite the prognostic importance of immune infiltrate in colorectal cancer, immunotherapy has demonstrated limited clinical activity in refractory metastatic proficient mismatch-repair (pMMR) colorectal cancer. This study explores combining anti–CTLA-4 and an anti–PD-L1 therapy in the preoperative management of resectable colorectal cancer liver metastases with the intent to improve immune responses in this disease setting.Patients and Methods: Patients with resectable colorectal cancer liver-only metastases received one dose of tremelimumab and durvalumab preoperatively followed by single-agent durvalumab postoperatively. Primary objectives were to determine feasibility and safety.Results: A total of 24 patients were enrolled between November 2016 and November 2019. Twenty-three patients received treatment [21 pMMR and 2 deficient mismatch-repair (dMMR)] and subsequently 17 (74%; 95% CI: 53%–88%) underwent surgical resection. Grade 3/4 treatment-related immune toxicity and postoperative grade 3/4 toxicity were seen in 5/23 (22%; 95% CI: 10%–44%) and 2/17 (12%; 95% CI: 2%–38%) patients. The median relapse-free survival (RFS) was 9.7 (95% CI: 8.1–17.8) months, and overall survival was 24.5 (95% CI: 16.5–28.4) months. Four patients demonstrated complete pathologic response, two dMMR patients and two POLE mutation patients. Pre- and post-tumor tissue analysis by flow cytometry, immunofluorescence, and RNA sequencing revealed similar levels of T-cell infiltration, but did demonstrate evidence of CD8+ and CD4+ activation posttreatment. An increase in B-cell transcriptome signature and B-cell density was present in posttreatment samples from patients with prolonged RFS.Conclusions: This study demonstrates the safety of neoadjuvant combination tremelimumab and durvalumab prior to colorectal cancer liver resection. Evidence for T- and B-cell activation following this therapy was seen in pMMR metastatic colorectal cancer.