Transcriptomic profiles of neoantigen-reactive T cells in human gastrointestinal cancers.

Tumor-infiltrating neoantigen-reactive T cells can mediate regression of metastatic gastrointestinal cancers yet remain poorly characterized. We performed immunological screening against personalized neoantigens in combination with single-cell RNA sequencing on tumor-infiltrating lymphocytes from bile duct and pancreatic cancer patients to characterize the transcriptomic landscape of neoantigen-reactive T cells. We found that most neoantigen-reactive CD8+ T cells displayed an exhausted state with significant CXCL13 and GZMA co-expression compared with non-neoantigen-reactive bystander cells. Most neoantigen-reactive CD4+ T cells from a patient with bile duct cancer also exhibited an exhausted phenotype but with overexpression of HOPX or ADGRG1 while lacking IL7R expression. Thus, neoantigen-reactive T cells infiltrating gastrointestinal cancers harbor distinct transcriptomic signatures, which may provide new opportunities for harnessing these cells for therapy.

Robust Antitumor Immunity in a Patient with Metastatic Colorectal Cancer Treated with Cytotoxic Regimens.

Microsatellite-stable (MSS) colorectal cancers are characterized by low mutation burden and limited immune-cell infiltration and thereby respond poorly to immunotherapy. Here, we report a case of metastatic MSS colorectal cancer with a robust anticancer immune response. The primary tumor was resected in 2012, and the patient received several cycles of chemotherapy until 2017. In 2018, the patient underwent a left hepatectomy to remove a new metastasis. Analysis of the metastatic tumor revealed a strong CD8+ T-cell response. A high frequency of CD8+ T cells coexpressed CD39 and CD103, a phenotype characteristic of tumor-reactive cells. Using whole-exome sequencing, we identified somatic mutations that generated peptides recognized by CD39+CD103+CD8+ T cells. The observed reactivity against the tumor was dominated by the response to a single mutation that emerged in the metastasis. Somatic mutations that were not immunogenic in the primary tumor led to robust CD8+ T-cell expansion later during disease progression. Our data suggest that the cytotoxic treatment regimen received by the patient might be responsible for this effect. Hence, the capacity of cytotoxic regimens to prime the immune system in colorectal cancer patients should be investigated further and might provide a rationale for combination with immunotherapy.

A Real-World Observational Cohort of Patients with Hepatocellular Carcinoma: Design and Rationale for TARGET-HCC.

This study describes the design of the TARGET-hepatocellular carcinoma (HCC) cohort and descriptive characteristics of the patient population at diagnosis among those who were enrolled in the cohort across academic and community clinical centers. TARGET-HCC is a 5-year, longitudinal, observational cohort of patients with HCC receiving care in usual clinical practice. Redacted clinical information, obtained from medical records, captures the natural history and management of the disease, including the safety and efficacy of treatment interventions used in usual clinical practice. Patients can complete patient-reported outcome measures and provide biological specimens for future translational studies. The TARGET-HCC study includes adults with histologic, cytologic, or radiologic diagnosis of HCC from academic and community centers in both the United States and Europe. A total of 1,841 participants were enrolled between January 9, 2017, and July 23, 2019, at 67 sites in the United States and Europe. To date, the most common liver disease etiology in the cohort continues to be hepatitis C, although nearly half had a nonviral etiology, including alcohol-related liver disease or nonalcoholic steatohepatitis. Most included patients were diagnosed at an early stage (Barcelona Clinic Liver Cancer Stage [BCLC] 0/A), but only approximately one third underwent curative treatment. Systemic therapy has been used in 7.3% of enrolled patients, including 45.7% of those with BCLC stage C tumors. Conclusion: Overall, the TARGET-HCC cohort allows for the assessment of patient characteristics and investigation of new treatment paradigms and sequencing with existing agents as well as novel regimens for HCC.

Transcriptional and immunohistological assessment of immune infiltration in pancreatic cancer.

Pancreatic adenocarcinoma is characterized by a complex tumor environment with a wide diversity of infiltrating stromal and immune cell types that impact the tumor response to conventional treatments. However, even in this poorly responsive tumor the extent of T cell infiltration as determined by quantitative immunohistology is a candidate prognostic factor for patient outcome. As such, even more comprehensive immunophenotyping of the tumor environment, such as immune cell type deconvolution via inference models based on gene expression profiling, holds significant promise. We hypothesized that RNA-Seq can provide a comprehensive alternative to quantitative immunohistology for immunophenotyping pancreatic cancer. We performed RNA-Seq on a prospective cohort of pancreatic tumor specimens and compared multiple approaches for gene expression-based immunophenotyping analysis compared to quantitative immunohistology. Our analyses demonstrated that while gene expression analyses provide additional information on the complexity of the tumor immune environment, they are limited in sensitivity by the low overall immune infiltrate in pancreatic cancer. As an alternative approach, we identified a set of genes that were enriched in highly T cell infiltrated pancreatic tumors, and demonstrate that these can identify patients with improved outcome in a reference population. These data demonstrate that the poor immune infiltrate in pancreatic cancer can present problems for analyses that use gene expression-based tools; however, there remains enormous potential in using these approaches to understand the relationships between diverse patterns of infiltrating cells and their impact on patient treatment outcomes.

Blockade of fibroblast activation protein in combination with radiation treatment in murine models of pancreatic adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a fibrotic stroma with a poor lymphocyte infiltrate, in part driven by cancer-associated fibroblasts (CAFs). CAFs, which express fibroblast activation protein (FAP), contribute to immune escape via exclusion of anti-tumor CD8+ T cells from cancer cells, upregulation of immune checkpoint ligand expression, immunosuppressive cytokine production, and polarization of tumor infiltrating inflammatory cells. FAP is a post-proline peptidase selectively expressed during tissue remodeling and repair, such as with wound healing, and in the tumor microenvironment by cancer-associated fibroblasts. We targeted FAP function using a novel small molecule inhibitor, UAMC-1110, and mice with germline knockout of FAP and concomitant knock-in of E. coli beta-galactosidase. We depleted CAFs by adoptive transfer of anti-ßgal T cells into the FAP knockout animals. Established syngeneic pancreatic tumors in immune competent mice were targeted with these 3 strategies, followed by focal radiotherapy to the tumor. FAP loss was associated with improved antigen-specific tumor T cell infiltrate and enhanced collagen deposition. However, FAP targeting alone or with tumor-directed radiation did not improve survival even when combined with anti-PD1 therapy. Targeting of CAFs alone or in combination with radiation did not improve survival. We conclude that targeting FAP and CAFs in combination with radiation is capable of enhancing anti-tumor T cell infiltrate and function, but does not result in sufficient tumor clearance to extend survival.

Regional Metastatic Behavior of Nonfunctional Pancreatic Neuroendocrine Tumors: Impact of Lymph Node Positivity on Survival.

OBJECTIVES: Literature addressing the significance of lymph node positivity in the management of nonfunctional pancreatic neuroendocrine tumors (PNETs) is conflicting. METHODS: The National Cancer Data Base was queried for patients who underwent surgical resection of nonfunctional PNETs between 1998 and 2011. Clinical data and overall survival were analyzed using χ and Cox proportional hazards regression. Multiple imputation was used as a comparative analysis because of the high number of patients missing data on tumor grade. RESULTS: Two thousand seven hundred thirty-five patients were identified. The overall incidence of lymph node metastasis was 51%. In the subset of patients with grade 1 tumors less than 1 cm, 24% had positive lymph nodes. Overall median survival for patients with negative lymph nodes was 11 years compared with 8 years for lymph node-positive patients (P < 0.001). On multivariate survival analysis, tumor grade, distant metastases, regional lymph node involvement, positive surgical margins, male sex, and older age were predictive of decreased overall survival. CONCLUSIONS: Lymph node positivity was associated with decreased overall survival. The incidence of lymph node involvement in resected low-grade tumors less than 1 cm is higher than previously reported. Patients selected for resection of PNETs should be offered lymphadenectomy for staging.

Analysis of 340 Patients with Solid Pseudopapillary Tumors of the Pancreas: A Closer Look at Patients with Metastatic Disease.

INTRODUCTION: Current literature addressing the treatment of solid pseudopapillary neoplasms (SPNs) of the pancreas is limited, particularly for patients with distant metastases. We aimed to define predictive indicators of survival in a large series of patients and assess the outcome of patients with distant metastases. METHODS: The National Cancer Database was queried for patients diagnosed with SPNs of the pancreas between 1998 and 2011. Single predictor univariate analyses were performed on variables including demographics, tumor characteristics, and surgery outcomes, and multivariate Cox proportional hazards survival analysis was then completed with backward elimination. RESULTS: Overall, 340 patients were identified: 82% were female, median age was 39 years, and 84% had no comorbidities. Patients undergoing any type of surgical resection experienced long-term survival (85% 8-year survival). Patients undergoing surgical resection (n = 296) had superior survival (hazard ratio [HR] 21 for no surgery, p < 0.0001), as did patients treated at academic centers and those with private insurance (HR 3.9, p = 0.009; HR 4.9, p = 0.007). Sex, age, tumor size, presence of lymph node metastases, positive surgical margins, and presence of distant metastases were not significant predictors of survival in multivariate analysis. Of 24 patients with distant metastases, seven were treated surgically and experienced long-term survival similar to that of patients without metastases treated surgically (HR 2, p = 0.48). CONCLUSION: SPNs of the pancreas are rare neoplasms with excellent overall survival; however, in a low number of patients they metastasize. Of the few patients with metastatic disease selected for resection, most experienced long-term survival.

Validation of Fistula Risk Score calculator in diverse North American HPB practices.

BACKGROUND: Fistula Risk Score (FRS) is a previously developed tool to assess the risk of clinically relevant postoperative pancreatic fistula (CR-POPF) following pancreatoduodenectomy (PD). METHODS: Prospectively collected databases from 4 university affiliated and non-affiliated HPB centers in United States and Canada were used. The influence of individual baseline characteristics, FRS and FRS group on CR-POPF was assessed in univariate and multivariate analyses. FRS calculator performance was assessed using a C-statistic. RESULTS: 444 patients were identified. Pathology, soft pancreas texture and pancreatic duct size were associated with CR-POPF rates (p < 0.001 for each); EBL was not (p = 0.067). The negligible risk group consisted of 50 (11.3%) patients, low risk of 118 (26.6%), moderate 234 (52.7%) and high risk group of 42 (9.5%) patients. The overall rate of CR-POPF was 20%. Of the patients in the negligible risk group, 2% developed CR-POPF, 13.6% of the low risk, 23.1% moderate and 42.9% in the high risk group (p < 0.001). Overall C-statistic was 0.719. CONCLUSION: FRS is robust and able to stratify the risk of developing CR-POPF following PD in diverse North American academic and non-academic institutions. The FRS should be used in research and to guide clinical management of patients post PD in these institutions.

Programmed cell death-1 blockade enhances response to stereotactic radiation in an orthotopic murine model of hepatocellular carcinoma.

AIM: Small, solitary hepatocellular carcinoma is curable with stereotactic radiation or other methods of tumor ablation, however, regional and systemic tumor recurrence occurs in over 70% of patients. Here we describe the ability of immunoradiotherapy to induce an antitumor immune response and delay the growth of tumors in immunocompetent mice. METHODS: A syngeneic hepatocellular carcinoma cell line (Hep-55.1c) was injected directly into the livers of C57BL/6 mice using ultrasound guidance, then tumors were treated with stereotactic radiation using a Small Animal Radiation Research Platform with computed tomography guidance. RESULTS: Delivery of three doses of 250 µg anti-programmed cell death protein-1 (αPD-1) antibody concurrently with 30 Gy stereotactic body radiation therapy in three fractions reduced the growth rate of tumors and improved survival (P < 0.05). Combined treatment was associated with increased CD8+ cytotoxic T cells in the tumor; depletion of CD8 T cells eliminated the efficacy of combined treatment. Combined treatment also induced expression of programmed cell death-1 ligand expression on tumor-infiltrating macrophages, and the tumors grew rapidly after αPD-1 treatment was discontinued. CONCLUSIONS: Tumor response to stereotactic radiation can be augmented by concurrent treatment with αPD-1. The efficacy of this combination therapy was transient, however, and treatment induced markers of adaptive immune resistance. These data are promising, but also indicate that mechanisms of immune resistance will need to be durably overcome for this combination to generate lasting immunity to protect against tumor recurrence.

Mertk on tumor macrophages is a therapeutic target to prevent tumor recurrence following radiation therapy.

Radiation therapy provides a means to kill large numbers of cancer cells in a controlled location resulting in the release of tumor-specific antigens and endogenous adjuvants. However, by activating pathways involved in apoptotic cell recognition and phagocytosis, irradiated cancer cells engender suppressive phenotypes in macrophages. We demonstrate that the macrophage-specific phagocytic receptor, Mertk is upregulated in macrophages in the tumor following radiation therapy. Ligation of Mertk on macrophages results in anti-inflammatory cytokine responses via NF-kB p50 upregulation, which in turn limits tumor control following radiation therapy. We demonstrate that in immunogenic tumors, loss of Mertk is sufficient to permit tumor cure following radiation therapy. However, in poorly immunogenic tumors, TGFß inhibition is also required to result in tumor cure following radiation therapy. These data demonstrate that Mertk is a highly specific target whose absence permits tumor control in combination with radiation therapy.

A hypofractionated radiation regimen avoids the lymphopenia associated with neoadjuvant chemoradiation therapy of borderline resectable and locally advanced pancreatic adenocarcinoma.

BACKGROUND: Preclinical studies have shown synergy between radiation therapy and immunotherapy. However, in almost all preclinical models, radiation is delivered in single doses or short courses of high doses (hypofractionated radiation). By contrast in most clinical settings, radiation is delivered as standard small daily fractions of 1.8-2 Gy to achieve total doses of 50-54 Gy (fractionated radiation). We do not yet know the optimal dose and scheduling of radiation for combination with chemotherapy and immunotherapy. METHODS: To address this, we analyzed the effect of neoadjuvant standard fractionated and hypofractionated chemoradiation on immune cells in patients with locally advanced and borderline resectable pancreatic adenocarcinoma. RESULTS: We found that standard fractionated chemoradiation resulted in a significant and extended loss of lymphocytes that was not explained by a lack of homeostatic cytokines or response to cytokines. By contrast, treatment with hypofractionated radiation therapy avoided the loss of lymphocytes associated with conventional fractionation. CONCLUSION: Hypofractionated neoadjuvant chemoradiation is associated with reduced systemic loss of T cells. TRIAL REGISTRATION: ClinicalTrials.gov NCT01342224, April 21, 2011; NCT01903083, July 2, 2013.

Optimizing Timing of Immunotherapy Improves Control of Tumors by Hypofractionated Radiation Therapy.

The anecdotal reports of promising results seen with immunotherapy and radiation in advanced malignancies have prompted several trials combining immunotherapy and radiation. However, the ideal timing of immunotherapy with radiation has not been clarified. Tumor bearing mice were treated with 20Gy radiation delivered only to the tumor combined with either anti-CTLA4 antibody or anti-OX40 agonist antibody. Immunotherapy was delivered at a single timepoint around radiation. Surprisingly, the optimal timing of these therapies varied. Anti-CTLA4 was most effective when given prior to radiation therapy, in part due to regulatory T cell depletion. Administration of anti-OX40 agonist antibody was optimal when delivered one day following radiation during the post-radiation window of increased antigen presentation. Combination treatment of anti-CTLA4, radiation, and anti-OX40 using the ideal timing in a transplanted spontaneous mammary tumor model demonstrated tumor cures. These data demonstrate that the combination of immunotherapy and radiation results in improved therapeutic efficacy, and that the ideal timing of administration with radiation is dependent on the mechanism of action of the immunotherapy utilized.

Preoperative computed tomography scan to predict pancreatic fistula after distal pancreatectomy using gland and tumor characteristics.

BACKGROUND: Preoperative risk stratification for postoperative pancreatic fistula in patients undergoing distal pancreatectomy is needed. METHODS: Risk factors for postoperative pancreatic fistula in 220 consecutive patients undergoing distal pancreatectomy at 2 major institutions were recorded retrospectively. Gland density was measured on noncontrast computed tomography scans (n = 101), and histologic scoring of fat infiltration and fibrosis was performed by a pathologist (n = 120). RESULTS: Forty-two patients (21%) developed a clinically significant pancreatic fistula within 90 days of surgery. Fat infiltration was significantly associated with gland density (P = .0013), but density did not predict pancreatic fistula (P = .5). Recursive partitioning resulted in a decision tree that predicted fistula in this cohort with a misclassification rate less than 15% using gland fibrosis (histology), density (HU), margin thickness (cm), and pathologic diagnosis. CONCLUSIONS: This multicenter study shows that no single perioperative factor reliably predicts postoperative pancreatic fistula after distal pancreatectomy. A decision tree was constructed for risk stratification.

Total pancreatectomy for pancreatic ductal adenocarcinoma: review of the National Cancer Data Base.

BACKGROUND: Total pancreatectomy is infrequently performed for pancreatic cancer. Perceived operative mortality and questionable survival benefit deter many surgeons. Clinical outcomes, described in single-center series, remain largely unknown. METHODS: The National Cancer Database was queried for cases of pancreatic ductal adenocarcinoma undergoing total pancreatectomy (1998-2011). Univariate survival analyses were performed for 21 variables: demographic (8), tumor characteristics (5), surgery outcomes (6), and adjuvant therapy (2). The Log-rank test of differences in Kaplan-Meier survival curves was used for categorical variables. Variables with p < 0.05 were included in a multivariate analysis. Cox proportional hazards regression was used to analyze continuous variables and multivariate models. RESULTS: 2582 patients with staging and survival data made up the study population. 30-day mortality was 5.5%. Median overall survival was 15 months, with 1, 3, and 5-year survival rates of 60%, 22%, and 13%, respectively. Age, facility type, tumor size and grade, lymph node positivity, margin positivity, and adjuvant therapy significantly impacted survival in multivariate analysis. CONCLUSION: Although total pancreatectomy is a reasonable option for selected patients with pancreatic ductal adenocarcinoma, survival of the entire group is limited. Operative mortality is improved from prior reports. Greater survival benefits were seen in younger patients with smaller, node negative tumors resected with negative margins in academic research centers.

Impact of lymph node status in patients with intrahepatic cholangiocarcinoma treated by major hepatectomy: a review of the National Cancer Database.

INTRODUCTION: Routine lymphadenectomy in the surgical treatment of intrahepatic cholangiocarcinoma (ICC) is not routinely performed. We aim to define predictive indicators of survival in patients with positive lymph nodes. METHODS: The National Cancer Data Base (NCDB) was queried for patients who underwent major hepatectomy for ICC between 1998 and 2011. Clinical and pathologic data were assessed using uni- and multi-variate analyses. A sub-analysis was performed on the 160 patients with positive lymph nodes. RESULTS: Of 849 patients with lymph node data, 57% had at least one lymph node examined. Median survival for lymph node negative patients was 37 months versus 15 months for lymph node positive patients. In lymph node positive patients, poorer survival was associated with not receiving chemotherapy (HR 1.83, p = 0.003), tumor size > 5 cm (p = 0.029), and older age (p < 0.0001). Lymph node positive patients age less than 45 had a median survival of 27 months. CONCLUSIONS: Overall survival in patients with lymph node metastases from ICC is poor. Adjuvant therapy was associated with a longer survival in lymph node positive patients, although prospective data are needed. Routine lymphadenectomy should be strongly considered to provide prognostic information and guidance for adjuvant therapy.

Multimodal treatment of unresectable hepatocellular carcinoma to achieve complete response results in improved survival.

INTRODUCTION: With technological advances, questions arise regarding how to best fit newer treatment modalities, such as transarterial therapies, into the treatment algorithm for patients with hepatocellular carcinoma (HCC). METHODS: Between 2005 and 2011, 128 patients initially treated with transarterial radioembolization or chemoembolization using drug-eluting beads were identified. The response was graded retrospectively. Toxicity was measured 1, 3, and 6 months after the first and last treatments. RESULTS: Sixty-five patients (53%) were advanced stage. Twenty patients (16%) had an initial complete response, but with additional treatments, this was increased to 46 (36%). Patients with a complete response as their best response to treatment had a median survival [95% confidence interval (CI)] of 5.77 (2.58, upper limit not yet reached) years, significantly longer than those whose best response was a partial response, 1.22 (0.84, 2.06) years and those with stable disease as their best response, 0.34 (0.29, 0.67) years. Repeated treatments did not increase toxicity. DISCUSSION: This retrospective review of patients treated for intermediate and advanced stage HCC revealed a significant survival advantage in patients who achieved a complete response. These data support use of a multi-modality approach to intermediate and advanced stage HCC, combining liver-directed treatments as necessary to achieve a complete response.

Expression of arginase I in myeloid cells limits control of residual disease after radiation therapy of tumors in mice.

An accumulating body of evidence demonstrates that radiation therapy can generate adaptive immune responses that contribute to tumor control. However, in the absence of additional immune therapy, the adaptive immune response is insufficient to prevent tumor recurrence or affect distant disease. It has been shown in multiple models that tumor-infiltrating myeloid cells exhibit alternative activation phenotypes and are able to suppress adaptive immune responses, and recent data suggests that the myeloid response in tumors treated with cytotoxic therapy limits tumor control. We hypothesized that tumor myeloid cells inhibit the adaptive immune response after radiation therapy through expression of the enzyme arginase I. Using a myeloid cell-specific deletion of arginase I in mice, we demonstrate an improved tumor control after radiation therapy. However, tumors still recurred despite the conditional knockdown of arginase I. Since multiple alternative factors may combine to inhibit adaptive immunity, we propose that targeting macrophage differentiation may be a more effective strategy than targeting individual suppressive pathways.

TGFß inhibition prior to hypofractionated radiation enhances efficacy in preclinical models.

The immune infiltrate in colorectal cancer has been correlated with outcome, such that individuals with higher infiltrations of T cells have increased survival independent of the disease stage. For patients with lower immune infiltrates, overall survival is limited. Because the patients with colorectal cancer studied have received conventional cancer therapies, these data may indicate that the pretreatment tumor environment increases the efficacy of treatments such as chemotherapy, surgery, and radiotherapy. This study was designed to test the hypothesis that an improved immune environment in the tumor at the time of treatment will increase the efficacy of radiotherapy. We demonstrate that inhibition of TGFß using the orally available small-molecule inhibitor SM16 improved the immune environment of tumors in mice and significantly improved the efficacy of subsequent radiotherapy. This effect was not due to changes in radiosensitivity, epithelial-mesenchymal transition, or changes in vascular function in the tumor; rather, this effect was dependent on adaptive immunity and resulted in long-term protective immunity in cured mice. These data demonstrate that immunotherapy is an option to improve the immune status of patients with poor tumor infiltrates and that pretreatment improves the efficacy of radiotherapy.

ß-Catenin signaling in hepatocellular cancer: Implications in inflammation, fibrosis, and proliferation.

ß-Catenin signaling is implicated in hepatocellular carcinoma (HCC), although its role in inflammation, fibrosis, and proliferation is unclear. Commercially available HCC tissue microarray (TMA) of 89 cases was assessed for ß-catenin, one of its transcriptional targets glutamine synthetase (GS), proliferation (PCNA), inflammation (CD45), and fibrosis (Sirius Red). HCC cells transfected with wild-type (WT) or mutant-ß-catenin were evaluated for ß-catenin-T cell factor transactivation by TOPFlash reporter activity and expression of certain targets. Hepatocyte-specific-serine-45-mutated ß-catenin transgenic mice (TG) and controls (Con) were used to study thioacetamide (TAA)-induced hepatic fibrosis and tumorigenesis. Sustained ß-catenin activation was only observed in mutant-, not WT-ß-catenin transfected HCC cells. Aberrant intratumoral ß-catenin stabilization was evident in 33% cases with 9% showing predominant nuclear with some cytoplasmic (N/C) localization and 24% displaying predominant cytoplasmic with occasional nuclear (C/N) localization. N/C ß-catenin was associated with reduced fibrosis (p=0.017) and tumor-wide GS staining (p<0.001) while C/N correlated with increased intratumoral inflammation (p=0.064) and proliferation (p=0.029). A small subset of HCC patients (15.5%) lacked ß-catenin staining and exhibited low inflammation and fibrosis (p<0.05). TG and Con mice exposed to TAA showed comparable development of fibrosis and progression to cirrhosis and HCC. Taken together the data suggests a complex relationship of ß-catenin, inflammation, fibrosis and HCC. GS staining is highly sensitive in identifying HCC with nuclear ß-catenin, which may in turn represent ß-catenin mutations, and does so with high negative predictive value. Also, ß-catenin mutations and cirrhosis do not appear to cooperate in HCC pathogenesis in mice and men.