Faculty Bibliography

Pancreatic cystic lesions (PCLs) have become more prevalent over time, particularly in asymptomatic individuals. Current screening guidelines for incidental PCLs offer a unified approach to surveillance and management, predicated on "worrisome features." Although PCLs are common in the general population, their prevalence may be higher in high-risk individuals (HRI, unaffected patients with specific familial and/or genetic risk factors). As more PCLs are diagnosed and more HRI identified, it is important to promote research that bridges data gaps and introduces nuance to risk assessment tools, ensuring tailoring of guidelines to the needs of HRI with varying pancreatic cancer risk factors.

UNLABELLED:Since its inception two years ago, the international, multicenter Pancreatic Cancer Early Detection (PRECEDE) Consortium has enrolled high-risk individuals (HRI) undergoing pancreatic ductal adenocarcinoma (PDAC) surveillance. Herein we aim to evaluate enrollment disparities in PRECEDE. Data on HRIs enrolled between May 2020 and March 2022 were collected, with HRIs defined as participants enrolled in PRECEDE meeting guideline-based criteria for PDAC surveillance. Of 1,273 HRIs enrolled, 1,113 were eligible for inclusion, with 47.2% meeting familial pancreatic cancer criteria without a known pathogenic variant (PV) and the remainder having a pathogenic variant in a PDAC-risk gene (CDKN2A, STK11, PRSS1, BRCA1, BRCA2, PALB2, ATM, MLH1, MSH2, MSH6, PMS2, or EPCAM). Study participants were predominantly from the United States (82.7%), the most common age range at enrollment was 60-69 years (37.4%), and a non-PDAC cancer was present in 32.4%. There were racial/ethnic- and sex-based disparities among enrolled subjects, as the majority of participants were female (65.9%) and self-reported white (87.7%), with only 2.9% having Hispanic ethnicity. While more than 97% of participants consented to utilize imaging data and biosamples for research, there was no difference in rate of consent based on race/ethnicity, sex, or age, thereby demonstrating uniform participation in research activities among all subgroups after enrollment. Ensuring that diversity of HRIs in PDAC surveillance programs mirrors the communities served by participating centers is important. Substantial racial/ethnic- and sex-based disparities persist among recently enrolled HRIs undergoing PDAC surveillance, and therefore reducing these disparities will be a major focus of the PRECEDE Consortium moving forward. PREVENTION RELEVANCE:Pancreatic cancer surveillance is critical to decreasing pancreatic cancer mortality; therefore, it is important that pancreatic cancer surveillance studies enroll diverse patients. We demonstrate that substantial racial/ethnic- and sex-based disparities exist amongst enrollment in the international PRECEDE consortium, highlighting the dire need for future efforts to reduce these disparities. See related Spotlight, p. 305.

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy that harbors mutations in homologous recombination-repair (HR-repair) proteins in 20%-25% of cases. Defects in HR impart a specific vulnerability to poly ADP ribose polymerase inhibitors and platinum-containing chemotherapy in tumor cells. However, not all patients who receive these therapies respond, and many who initially respond ultimately develop resistance. Inactivation of the HR pathway is associated with the overexpression of polymerase theta (Polθ, or POLQ). This key enzyme regulates the microhomology-mediated end-joining (MMEJ) pathway of double-strand break (DSB) repair. Using human and murine HR-deficient PDAC models, we found that POLQ knockdown is synthetically lethal in combination with mutations in HR genes such as BRCA1 and BRCA2 and the DNA damage repair gene ATM. Further, POLQ knockdown enhances cytosolic micronuclei formation and activates signaling of cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING), leading to enhanced infiltration of activated CD8+ T cells in BRCA2-deficient PDAC tumors in vivo. Overall, POLQ, a key mediator in the MMEJ pathway, is critical for DSB repair in BRCA2-deficient PDAC. Its inhibition represents a synthetic lethal approach to blocking tumor growth while concurrently activating the cGAS-STING signaling pathway to enhance tumor immune infiltration, highlighting what we believe to be a new role for POLQ in the tumor immune environment.

BACKGROUND:Germline BRCA1 and BRCA2 mutations (gBRCAm) can inform pancreatic cancer (PC) risk and treatment but most of the available information is derived from white patients. The ethnic and geographic variability of gBRCAm prevalence and of germline BRCA (gBRCA) testing uptake in PC globally is largely unknown. MATERIALS AND METHODS/METHODS:We carried out a systematic review and prevalence meta-analysis of gBRCA testing and gBRCAm prevalence in PC patients stratified by ethnicity. The main outcome was the distribution of gBRCA testing uptake across diverse populations worldwide. Secondary outcomes included: geographic distribution of gBRCA testing uptake, temporal analysis of gBRCA testing uptake in ethnic groups, and pooled proportion of gBRCAm stratified by ethnicity. The study is listed under PROSPERO registration number #CRD42022311769. RESULTS:A total of 51 studies with 16 621 patients were included. Twelve of the studies (23.5%) enrolled white patients only, 10 Asians only (19.6%), and 29 (56.9%) included mixed populations. The pooled prevalence of white, Asian, African American, and Hispanic patients tested per study was 88.7%, 34.8%, 3.6%, and 5.2%, respectively. The majority of included studies were from high-income countries (HICs) (64; 91.2%). Temporal analysis showed a significant increase only in white and Asians patients tested from 2000 to present (P < 0.001). The pooled prevalence of gBRCAm was: 3.3% in white, 1.7% in Asian, and negligible (<0.3%) in African American and Hispanic patients. CONCLUSIONS:Data on gBRCA testing and gBRCAm in PC derive mostly from white patients and from HICs. This limits the interpretation of gBRCAm for treating PC across diverse populations and implies substantial global and racial disparities in access to BRCA testing in PC.

The tumor microenvironment (TME) in pancreatic ductal adenocarcinoma (PDAC) is a complex ecosystem that drives tumor progression; however, in-depth single cell characterization of the PDAC TME and its role in response to therapy is lacking. Here, we perform single-cell RNA sequencing on freshly collected human PDAC samples either before or after chemotherapy. Overall, we find a heterogeneous mixture of basal and classical cancer cell subtypes, along with distinct cancer-associated fibroblast and macrophage subpopulations. Strikingly, classical and basal-like cancer cells exhibit similar transcriptional responses to chemotherapy and do not demonstrate a shift towards a basal-like transcriptional program among treated samples. We observe decreased ligand-receptor interactions in treated samples, particularly between TIGIT on CD8 + T cells and its receptor on cancer cells, and identify TIGIT as the major inhibitory checkpoint molecule of CD8 + T cells. Our results suggest that chemotherapy profoundly impacts the PDAC TME and may promote resistance to immunotherapy.

Background: Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer typically discovered at incurable stages. The PRECEDE Consortium was established to accelerate early detection by using a large-scale, collaborative, innovative model, predicated on standardized collection of demographic, clinical, and imaging data from high-risk individuals (HRI). Here we report the initial pancreas imaging findings in Cohort 1, representing HRI with familial pancreatic cancer (FPC) or pathogenic germline variants (PGV) in PDAC susceptibility genes with a 1st or 2nd degree relative with PDAC.
Method(s): The PRECEDE Consortium (NCT04970056) began enrollment in 5/2020. HRI enrolled prospectively at centers worldwide into one of 7 cohorts based on personal and/or family history of PDAC and PGV status. PRECEDE's planned enrollment is 10,000 patients. Data sharing is required to join PRECEDE, facilitated by a standardized data collection system and central database (PRECEDELink). Imaging (MRI/MRCP and EUS) is performed using standardized image acquisition and reporting templates. Imaging and clinical sequencing data are stored and analyzed in the PRECEDE data cloud.
Result(s): By 9/16/2022, 26 sites enrolled 3156 patients in 7 cohorts, with 1716 in Cohort 1. Cohort 1 was 60% female, 80% white; 48% met FPC criteria, and 52% were PGV carriers. Within Cohort 1, 658 FPC and 965 PGV (1353 total, 79%) underwent imaging (68% MRI; 32% EUS). Overall, 573/1353 (42%) had pancreas abnormalities: 320/573 (49%) FPC, and 253/573 (36%) PGV (OR [95% CI] 1.65 [1.32-2.06], P<0.001). Cysts were the most common abnormality, present in 549/1353 (41%) and accounting for 310/320 (97%) FPC and 239/253 (94%) PGV HRI abnormalities. Of 549 HRI with cysts, 262 (48%) had 1 cyst, including 137/310 (44%) FPC and 125/239 (52%) PGV HRI (OR 1.43 [1.07-1.92], P = .012) The remaining 287/549 (52%) had >=2 cysts, including 173/310 (56%) FPC and 114/239 (48%) PGV HRI (OR 1.98 [1.49-2.64], P<0.001). Worrisome features occurred in 83/ 1353 (6.1%) including: 14 (1%) cyst > 2 cm, 7 (0.5%) cyst >=3 cm, 35 (2.6%) main pancreatic duct (MPD) diameter >=5 mm; 2 (0.15%) duct strictures; and 25 (1.8%) solid masses. Solid masses included 1 (0.07%) PDAC, 9 (0.7%) neuroendocrine tumors, and 15 (1.1%) benign lesions (e.g. lipoma, splenule).
Conclusion(s): Pancreatic abnormalities are common in a cohort of 1353 HRI enrolled in PRECEDE; 6.1% of HRI had findings with worrisome features and clinical implications. Multiple cysts were significantly more common in FPC HRI (OR 1.98); worrisome findings did not differ between FPC and PGV groups. The longitudinal study of this growing HRI cohort with standardized imaging and matched comprehensive epidemiological, clinical, and laboratory data, along with germline testing, will provide critical information and understanding of PDAC risk, and augment existing clinical decision-making models governing surveillance and treatment

Background: The international, multi-center Pancreatic Cancer Early Detection (PRECEDE) Consortium enrolls high-risk individuals (HRIs) undergoing pancreatic ductal adenocarcinoma (PDAC) surveillance. Enrollment began in 2020, and despite challenges related to the COVID-19 pandemic, the PRECEDE Consortium rapidly accrued a large cohort of HRIs. The purpose of this study is to describe the characteristics of this cohort and assess racial, ethnic, and sex-based disparities.
Method(s): The PRECEDE Consortium (NCT04970056) is a prospective, multicenter study focused on improving survival from PDAC through early detection. Data from all HRIs who met criteria for PDAC surveillance and enrolled between May 2020 - March 2022 were collected and included in the analysis.
Result(s): During the study period, 1299 HRIs enrolled in PRECEDE at 32 centers. HRIs were excluded if enrollment data was incomplete or criteria for PDAC surveillance were not met. Of 1113 who were included, 47.2% met criteria for familial pancreatic cancer (FPC) and 45.4% had a family history of PDAC along with a PV in a PDAC-risk gene (BRCA1, BRCA2, PALB2, ATM, MLH1, MSH2, MSH6, PMS2, or EPCAM). The remainder had familial atypical mole melanoma syndrome (5.7%), Peutz- Jeghers syndrome (1.6%), or hereditary pancreatitis (0.2%). More females than males enrolled (65.9% vs. 33.5%). The distribution of HRIs by race and ethnicity is depicted; the majority identified as white (87.7%). Study participants were primarily from the US (82.7%), the median age was 61 (27-85) and 18.5% had Ashkenazi Jewish ancestry. Nearly all HRIs consented to allow access to imaging data (99.6%), collection of germline DNA (97.7%), and biosample collection (99.5%). There were no race, ethnicity, or sex-based differences in rates of consent for collection of imaging, DNA, or biosamples.
Conclusion(s): Enrollment of HRIs in prospective studies of PDAC surveillance is essential for advancing early detection research in PDAC. A distinct advantage of the PRECEDE Consortium for examining enrollment disparities is that recruitment began in 2020, providing a unique and current snapshot of the international PDAC surveillance landscape. Despite the recent attention on addressing disparities in healthcare delivery, significant racial, ethnic, and sex-based disparities persisted in the cohort of HRIs enrolled in the PRECEDE Consortium. Ensuring that the diversity of participants in the PRECEDE Consortium mirrors the communities served by participating centers is crucial. Further examining and addressing the reasons for these disparities is a major focus of the PRECEDE Consortium moving forward

Background: Metastatic colorectal (CRC), pancreatic (PANC), and gastroesophageal cancers are the leading causes of GI cancer-related mortality (5-y survival: 15%, 3%, and 5%-6%, respectively) (ACS 2022). HLA LOH is a recurrent mechanism of immune escape observed in 15%-20% of GI cancers (Hecht R., ASCO GI 2022). The Tmod platform is a logic-gated chimeric antigen receptor (CAR) T-cell modular system, comprising a carcinoembryonic antigen (CEA)- or mesothelin (MSLN)-targeting CAR activator and a separate HLA-A*02-targeting blocker receptor. Both in vitro/in vivo, Tmod CAR T therapy kills cells with HLA-A*02 LOH (tumor) without harming cells with retained HLA-A*02 expression (normal). However, HLA-A*02 LOH can only be therapeutically exploited if patients are identifiable through a feasible and timely clinical workflow.
Method(s): We established a biobanking protocol (BASECAMP-1, NCT04981119) to determine whether HLA-A*02 LOH patients can be prospectively identified. Patients with CRC, PANC, or non-small cell lung cancer (NSCLC), and a high risk for incurable relapse, were screened first using a standard HLA assay. Heterozygous HLAA* 02 positive tumor samples were then assessed for LOH using a bioinformatic algorithm applied via the Tempus xT platform.
Result(s): As of Sep 1, 2022, 83 patients were consented at 4 institutions. HLA status was obtained from 70 patients and 28 were identified as HLA-A*02:01 heterozygous (40%; expected frequency based on USA NMDP data, 27.6%). LOH results were available for 16 patients; 4 LOH-positive patients were identified (25%, 2 PANC, 2 NSCLC). The LOH assay sensitivity declines below a tumor purity of 40% (Hecht R., ASCO GI 2022). Six patients had a tumor purity of 20% (all with PANC, a tumor known for high stromal content), limiting possible LOH detection. The impact of tumor purity on LOH sensitivity was highlighted in a patient with a low initial sample tumor purity (30%) that resulted in a 41% probability of HLA-A*02:01 LOH (below positive threshold). A second sample with a higher tumor purity (70%), obtained from formalin-fixed, paraffin-embedded sections, resulted in a 92% probability of HLA-A*02:01 LOH (positive).
Conclusion(s): BASECAMP-1 prospective identification of HLA-A*02 LOH is feasible in the real-world setting. The frequencies of the HLA-A*02 allele and of HLA-A*02 LOH in this cohort mirrored expected population frequencies. LOH results can be obtained within a clinically feasible workflow and timeframe, although samples with a,40% tumor purity have a reduced sensitivity for LOH detection, an issue recurrently observed in patients with PANC. The BASECAMP-1 strategy enables prospective identification of appropriate patients for future therapeutic clinical trials using Tmod CEA and MSLN logic-gated CAR T cells