Evaluating Mismatch Repair Deficiency in Pancreatic Adenocarcinoma: Challenges and Recommendations

Metastatic pancreatic cancer with activating BRAF V600E mutations: A case report

BACKGROUND

Pancreatic cancer (PC) is a highly malignant tumor that is resistant to chemotherapy, radiotherapy and immunotherapy. Combination chemotherapy regimens are the standard first-line regimens for metastatic disease, with a median survival < 12 months. Although recurrent genomic alterations such as the BRAF V600E mutation have been reported in PC, evidence supporting the clinical effectiveness of molecularly guided targeted therapies is limited.

CASE SUMMARY

We report a case of a 33-year-old male who was referred to our department with weight loss of 5 kg in 2 months, anorexia and abdominal pain. Imaging showed extensive lesions involving the pancreas, liver, bones, muscles and lymph nodes accompanied by elevated carbohydrate antigen 19-9 (CA19-9) and carcinoembryonic antigen (CEA). Biopsy yielded a diagnosis of PC. Treatment with gemcitabine and nab-paclitaxel was initiated, but the disease progressed in < 2 months even though the patient’s general condition improved. Molecular testing revealed the presence of BRAF mutation. Dabrafenib/trametinib combination therapy was introduced, and the patient was treated for 2 months with a decrease in CA19-9 and CEA levels, but he died after 2 months of treatment.

CONCLUSION

BRAF alterations are infrequent in PC. This case highlights the significance of molecular profiling in patients with PC, especially in patients with a high tumor burden.

Colorectal Tumors in Diverse Patient Populations Feature a Spectrum of Somatic Mutational Profiles

Admixed populations, including the Hispanic/Latino/a community, are underrepresented in cancer genetic/genomic studies. Leveraging the Latino Colorectal Cancer Consortium (LC3) and other existing datasets, we analyzed whole-exome sequencing data on tumor/normal pairs from 718 individuals with colorectal cancer to map somatic mutational features by ethnicity and genetic similarity. Global proportions of African, Asian, European, and Native American genetic ancestries were estimated using ADMIXTURE. Associations between these proportions and somatic mutational features were examined using logistic regression. APC, TP53, and KRAS were the top three mutated genes across all participants and in the subset of Latino individuals in LC3. In analyses examining recurrently mutated genes, tumors from patients of Latino ethnicity had fewer KRAS and PIK3CA mutations compared with tumors from non-Latino patients. Genetic ancestry overall was associated with CDC27 mutation status, and African genetic ancestry was associated with SMAD2 mutation status. In exome-wide analyses, African genetic ancestry was significantly associated with higher odds of mutation in KNCN and TMEM184B. Native American genetic ancestry was associated with a lower frequency of microsatellite instability-high tumors. The SBS11 mutational signature was associated with Native American genetic ancestry as well as Latino ethnicity. In an independent replication dataset, MSK-IMPACT, estimates of association were largely consistent in direction but nonsignificant. A meta-analysis of LC3 and MSK-IMPACT showed that African genetic ancestry was significantly associated with KRAS mutation status and MSI status. This work facilitates precision medicine initiatives by providing insights into the contribution of genetic ancestry to molecular features of colorectal tumors. Significance: Analysis of tumors from various populations can broadly characterize genomic landscapes and enhance precision medicine strategies.

Long Non-Coding RNAs and RNA-Binding Proteins in Pancreatic Cancer Development and Progression

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer and is responsible for about 467,000 cancer deaths annually. An oftentimes asymptomatic early phase of this disease results in a delayed diagnosis, and patients often present with advanced disease. Current treatment options have limited survival benefits, and only a minor patient population carries actionable genomic alterations. Hence, innovative personalized treatment strategies that consider molecular, cellular and functional analyses are urgently needed for pancreatic cancer patients. However, the majority of the genetic alterations found in PDAC are currently undruggable, or patients' response is not as expected. Therefore, non-genomic biomarkers and alternative molecular targets should be considered in order to advance the clinical management of PDAC patients. In line with this, recent gene expression and single-cell transcriptome analyses have identified molecular subtypes and transcriptional cell states that affect disease progression and drug efficiency. In this review, we will introduce long non-coding RNAs (lncRNAs) as well as RNA-binding proteins (RBPs) that are able to modulate the transcriptome of a cell through diverse mechanisms, thereby contributing to disease progression. We will provide a brief overview about the general functions of lncRNAs and RBPs, respectively. Subsequently, we will highlight selected lncRNAs and RBPs that have been shown to play a role in PDAC development, progression and drug response. Finally, we will present strategies aiming to interfere with the expression and function of lncRNAs and RBPs.

Deficient Mismatch Repair and Microsatellite Instability in Solid Tumors

The integrity of the genome is maintained by mismatch repair (MMR) proteins that recognize and repair base mismatches and insertion/deletion errors generated during DNA replication and recombination. A defective MMR system results in genome-wide instability and the progressive accumulation of mutations. Tumors exhibiting deficient MMR (dMMR) and/or high levels of microsatellite instability (termed "microsatellite instability high", or MSI-H) have been shown to possess fundamental differences in clinical, pathological, and molecular characteristics, distinguishing them from their "microsatellite stable" (MSS) counterparts. Molecularly, they are defined by a high mutational burden, genetic instability, and a distinctive immune profile. Their distinct genetic and immunological profiles have made dMMR/MSI-H tumors particularly amenable to treatment with immune checkpoint inhibitors (ICIs). The ongoing development of biomarker-driven therapies and the evaluation of novel combinations of immune-based therapies, with or without the use of conventional cytotoxic treatment regimens, continue to refine treatment strategies with the goals of maximizing therapeutic efficacy and survival outcomes in this distinct patient population. Moreover, the resultant knowledge of the mechanisms by which these features are suspected to render these tumors more responsive, overall, to immunotherapy may provide information regarding the potential optimization of this therapeutic approach in tumors with proficient MMR (pMMR)/MSS tumors.

Survival of Patients with Resected Microsatellite Instability-High, Mismatch Repair Deficient, and Lynch Syndrome-Associated Pancreatic Ductal Adenocarcinomas

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) remains a challenging disease due to its aggressiveness, late-stage diagnosis, and limited treatment options. Microsatellite instability-high (MSI-H) cancers are susceptible to immune checkpoint inhibitors. Survival outcomes for patients with MSI-H PDAC are unknown as the disease is rare.

METHODS

This study included patients with PDACs surgically resected from 1990 to 2023, and those with germline or sporadic pathogenic variants in DNA mismatch repair genes were identified. The study matched MSI-H, mismatch repair-deficient (MMRd), and Lynch syndrome (LS)-associated PDAC cases (on age, gender, and year of surgery) with microsatellite-stable (MSS), mismatch repair-proficient, or non-LS-associated PDAC cases in a 1:2 ratio. A generalized estimating equation Cox model with a robust sandwich estimator was used to compare overall survival (OS) in the matched cohorts.

RESULTS

Of 936 cases, 18 were included. Eight cases were MSI-H/MMRd, two were MSI/IHC-indeterminate, seven were MSS, and one was not tested for MSI. Nine patients had LS (MLH1 [n = 1], MSH2 [n = 4], MSH6 [n = 1], PMS2 [n = 3]), and nine patients had sporadic pathogenic variants in DNA MMR genes (MLH1 [n = 4], MSH6 [n = 5]). After matching to 36 control patients, the MSI-H/MMRd/LS PDACs had a significantly better OS (hazard ratio [HR], 0.36 [95% confidence interval [CI], 0.18-0.73; p = 0.005]; 5-year OS: MSI-H 77% [95% CI 58-100%] vs. MSS 27% [95% CI 15-51%]).

CONCLUSION

Before routine use of immune checkpoint inhibitors, the patients with MSI-H, MMRd, and LS-associated PDACs displayed significantly better survival than the patients with MSS, MMR-proficient, non-LS-associated PDACs. It is expected that survival for this cohort will further improve with increased availability of immunotherapy.

Novel Therapies for Pancreatic Cancer

Pancreatic adenocarcinoma (PDAC) unfortunately remains a highly fatal disease with a 5-year survival rate of only 11%. If surgical resection is not possible, systemic chemotherapy represents the standard-of-care approach to management. Combination chemotherapy regimens using fluorouracil (fluorouracil, oxaliplatin, leucovorin, and irinotecan; and fluorouracil, leucovorin, and oxaliplatin) or gemcitabine with albumin-bound paclitaxel have the potential to improve overall survival for patients with advanced disease. With the increasing understanding of the molecular drivers of pancreatic cancer, novel therapeutic approaches have made incremental progress for these patients. The molecular landscape of PDAC has been studied extensively. Approximately 90% of PDACs harbor mutations in the KRAS gene, a driver mutation that has long been considered undruggable. However, novel KRAS inhibitors have shown therapeutic promise in early-phase clinical trials, with larger studies ongoing. Less frequently encountered genomic aberrations that have therapeutic potential include NRG, BRAF, NTRK, HER2, BRCA, PALB2, and claudin. Immune checkpoint inhibitors have unfortunately yielded disappointing efficacy for the majority of patients with pancreatic cancer, except for those with tumors exhibiting deficiency in mismatch repair proteins. Alternative approaches to incorporate immunotherapy have shown more promise such as use of immune checkpoint inhibitors for selected patients in the maintenance setting and potential vaccine therapies in the postsurgery adjuvant setting. It is vital to perform molecular profiling in all patients with PDAC to identify potential treatment targets, and to enroll patients in clinical trials whenever possible.

Current status of cancer genome medicine for pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis; however, advancements in cancer genome profiling using next-generation sequencing have provided new perspectives. KRAS mutations are the most frequently observed genomic alterations in patients with PDAC. However, until recently, it was not considered a viable therapeutic target. Although KRAS G12C mutations for which targeted therapies are already available are infrequent in PDAC, treatments targeting KRAS G12D and pan-KRAS are still under development. Similarly, new treatment methods for KRAS, such as chimeric antigen receptor T-cell therapy, have been developed. Several other potential therapeutic targets have been identified for KRAS wild-type PDAC. For instance, immune checkpoint inhibitors have demonstrated efficacy in PDAC treatment with microsatellite instability-high/deficient mismatch repair and tumor mutation burden-high profiles. However, for other PDAC cases with low immunogenicity, combination therapies that enhance the effectiveness of immune checkpoint inhibitors are being considered. Additionally, homologous recombination repair deficiencies, including BRCA1/2 mutations, are prevalent in PDAC and serve as important biomarkers for therapies involving poly (adenosine diphosphate-ribose) polymerase inhibitors and platinum-based therapies. Currently, olaparib is available for maintenance therapy of BRCA1/2 mutation-positive PDAC. Further therapeutic developments are ongoing for genetic abnormalities involving BRAF V600E and the fusion genes RET, NTRK, NRG, ALK, FGFR2, and ROS1. Overcoming advanced PDAC remains a formidable challenge; however, this review outlines the latest therapeutic strategies that are expected to lead to significant advancements.

Immune-Based Strategies for Pancreatic Cancer in the Adjuvant Setting

Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related mortality in the United States, with poor overall survival across all stages. Less than 20% of patients are eligible for curative surgical resection at diagnosis, and despite adjuvant chemotherapy, most will experience disease recurrence within two years. The incorporation of immune-based strategies in the adjuvant setting remains an area of intense investigation with unrealized promise. It offers the potential of providing durable disease control for micro-metastatic disease following curative intent surgery and enabling personalized treatments based on mutational neoantigen profiles derived from resected specimens. However, most of these attempts have failed to demonstrate significant clinical success, likely due to the immunosuppressive tumor microenvironment (TME) and individual genetic heterogeneity. Despite these challenges, immune-based strategies, such as therapeutic vaccines targeted towards neoantigens, have demonstrated promise via immune activation and induction of T-cell tumor infiltration. In this review, we will highlight the foundational lessons learned from previous clinical trials of adjuvant immunotherapy, discussing the knowledge gained from analyses of trials with disappointing results. In addition, we will discuss how these data have been incorporated to design new agents and study concepts that are proving to be exciting in more recent trials, such as shared antigen vaccines and combination therapy with immune-checkpoint inhibitors and chemotherapy. This review will evaluate novel approaches in ongoing and future clinical studies and provide insight into how these immune-based strategies might evolve to address the unique challenges for treatment of PDAC in the adjuvant setting.

Clinical utility of comprehensive genomic profiling for advanced pancreatic cancer: insights from real-world data analysis

BACKGROUND

Precision medicine is a promising therapeutic strategy for pancreatic cancer. However, only a few patients are eligible for genotype-matched treatments because of the low detection rate of actionable genomic alterations, and the clinical application of comprehensive genomic profiling (CGP) in pancreatic cancer has not been completely investigated. CGP provides considerable information, including the prognosis and eligibility of patients for genotype-matched treatments, which can guide physicians' treatment strategies. This study aimed to investigate the contribution of CGP to patient outcomes.

METHODS

This single-center retrospective cohort study enrolled patients with recurrent or metastatic pancreatic cancer with adenocarcinoma or adenosquamous carcinoma who underwent systemic chemotherapy between April 2018 and April 2022. We reviewed the medical records for patient characteristics, survival, and genomic information. We compared overall survival (OS) between patients who received CGP (CGP group) and those who did not (non-CGP group).

RESULTS

Of 111 eligible patients, 59 underwent CGP. Median OS was significantly longer in the CGP than the non-CGP group (25.2 vs. 11.8 months; hazard ratio, 0.49; P = 0.0013). Six patients (10.2%) underwent genotype-matched treatments, with a median OS of 35.5 months, compared to 17.0 months for those who did not. The CGP group demonstrated a higher transition rate to subsequent chemotherapy than did the non-CGP group (76.3% vs. 48.1%, P = 0.0030).

CONCLUSIONS

OS was prolonged in patients with pancreatic cancer who underwent CGP, probably due to its influence on physicians' treatment strategies. These findings highlight the importance of the proactive and timely implementation of CGP in patients with pancreatic cancer.

Case Report: Medullary carcinoma of the pancreas with MLH1 promoter hypermethylation, induced deficient mismatch repair, successfully treated with an immune checkpoint inhibitor

We report the case of a 75-year-old woman with a pancreatic body mass. Pathological findings from endoscopic ultrasonography-guided fine-needle aspiration revealed medullary carcinoma of the pancreas (MCP). Deficient mismatch repair (dMMR) and high microsatellite instability (MSI-H) were identified through immunohistochemistry and next generation sequencing, respectively. While immunohistochemistry suggested MLH1 abnormality, no MLH1 mutation was; hypermethylation of the MLH1 promoter was later confirmed via bisulfite sequencing. The patient initially received nab-paclitaxel plus gemcitabine, achieving tumor shrinkage. Upon tumor regrowth, she was treated with the anti-programmed cell death-1 immune checkpoint inhibitor (ICI) pembrolizumab, which resulted in significant tumor reduction. This is the first case report of MCP with dMMR/MSI-H due to MLH1 promoter hypermethylation, effectively treated with an ICI.

Genetic medicine of familial and hereditary pancreatic cancer: Recent update in the era of precision cancer medicine

In Japan, 5 years have passed since the initiation of precision cancer medicine, and recent data accumulation in familial pancreatic cancer (FPC) and hereditary pancreatic cancer is outstanding. Multigene germline panel tests (MGPTs) have revealed that 7%-18% of patients with pancreatic cancer (PC) harbor pathogenic germline variants (PGVs), almost equal to the levels of breast, ovarian, endometrial, and colorectal cancers, with a higher incidence in FPC (14%-26%). The majority of PGVs seen in PC patients are clinically actionable and associated with homologous recombination (HR) pathways (6%-10%, particularly BRCA1/2 in 5%-6%), and the clinical guidelines recommend or propose genetic testing for all PC patients. Consensus guidelines have been established for most of the hereditary syndromes associated with PC risks, and surveillances of the pancreas and other at-risk organs are recommended for PGV carriers. Hereditary breast and ovarian cancer (HBOC) is the commonest hereditary cancer syndrome that has moderately increasing life-time risks of PC (3%-7% in Western countries); however, recent Japanese research demonstrated a higher risk level (BRCA1: 16%, BRCA2: 14%). Moreover, recent evidence has suggested a risk linkage between PC and ovarian cancer in HBOC pedigrees. High scores of homologous recombination deficiency suggest biallelic dysfunction of BRCA or other HR-related genes, and the likely effectiveness of platinum agents and PARP inhibitors against PCs. Remote counseling and testing are possible option in the future genetic medicine. As PC ranks in the second commonest target of precision cancer medicine in Japan, we must treat the patients and manage their at-risk relatives efficiently.

Clonal Heterogeneity in Human Pancreatic Ductal Adenocarcinoma and Its Impact on Tumor Progression

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer characterized by profound desmoplasia and cellular heterogeneity, which cannot be fully resolved using traditional bulk sequencing approaches. To understand the contribution of this heterogeneity to PDAC biology, we analyzed a large cohort of primary human PDAC samples (n = 62), profiling 443,451 single cells and 53,236 spatial transcriptomic spots using a combined single-cell RNA sequencing and spatial transcriptomics approach. Our analysis revealed significant intratumoral heterogeneity, with multiple genetically distinct neoplastic clones co-existing within individual tumors. These clones exhibited diverse transcriptional states and subtype profiles, challenging the traditional binary classification of PDAC into basal and classical subtypes; instead, our findings support a transcriptional continuum influenced by clonal evolution and spatial organization. Additionally, these clones each interacted uniquely with surrounding cell types in the tumor microenvironment. Phylogenetic analysis uncovered a rare but consistent classical-to-basal clonal transition associated with MYC amplification and immune response depletion, which were validated experimentally, suggesting a mechanism driving the emergence of a more aggressive basal clonal phenotype. Spatial analyses further revealed dispersed clones enriched for epithelial-to-mesenchymal transition (EMT) activity and immune suppression, correlating with metastatic potential and colonization of lymph node niches. These dispersed clones tended to transition toward a basal phenotype, contributing to disease progression. Our findings highlight the critical role of clonal diversity, transcriptional plasticity, and TME interactions in shaping human PDAC biology. This work provides new insights into the molecular and spatial heterogeneity of PDAC and offers potential avenues for therapeutic intervention targeting clonal evolution and the mechanisms driving metastasis.

Clinicogenomic landscape of pancreatic adenocarcinoma identifies KRAS mutant dosage as prognostic of overall survival

Nearly all pancreatic adenocarcinomas (PDAC) are genomically characterized by KRAS exon 2 mutations. Most patients with PDAC present with advanced disease and are treated with cytotoxic therapy. Genomic biomarkers prognostic of disease outcomes have been challenging to identify. Herein leveraging a cohort of 2,336 patients spanning all disease stages, we characterize the genomic and clinical correlates of outcomes in PDAC. We show that a genomic subtype of KRAS wild-type tumors is associated with early disease onset, distinct somatic and germline features, and significantly better overall survival. Allelic imbalances at the KRAS locus are widespread. KRAS mutant allele dosage gains, observed in one in five (20%) KRAS-mutated diploid tumors, are correlated with advanced disease and demonstrate prognostic potential across disease stages. With the rapidly expanding landscape of KRAS targeting, our findings have potential implications for clinical practice and for understanding de novo and acquired resistance to RAS therapeutics.

A High-Affinity Monoclonal Antibody Against the Pancreatic Ductal Adenocarcinoma Target, Anterior Gradient-2 (AGR2/PDIA17)

BACKGROUND/OBJECTIVES

Anterior Gradient-2 (AGR2/PDIA17) is a member of the protein disulfide isomerase (PDI) family of oxidoreductases. AGR2 is up-regulated in several solid tumors, including pancreatic ductal adenocarcinoma (PDAC). Given the dire need for new therapeutic options for PDAC patients, we investigated the expression and function of AGR2 in PDAC and developed a novel series of affinity-matured AGR2-specific single-chain variable fragments (scFvs) and monoclonal antibodies.

RESULTS

We found that AGR2 was expressed in approximately 90% of PDAC but not normal pancreas biopsies, and the level of AGR2 expression correlated with increasing disease stage. AGR2 expression was inversely related to SMAD4 status in PDAC and colorectal cancer cell models and was secreted from cells into their media. In normal tissues, a high density of AGR2 was detected in the epithelium of cells in the digestive tract but was lacking in most other normal tissue systems. The addition of recombinant AGR2 to cell culture and genetic overexpression of AGR2 increased the adhesion, motility, and invasiveness of both human and mouse PDAC cells. Human phage display library screening led to the discovery of multiple AGR2-specific scFv clones that were affinity-matured to produce monoclonal antibody (MAb) clones with low picomolar binding affinity (S31R/A53F/Y). These high-affinity MAbs inhibited AGR2-mediated cell adhesion, migration, and binding to LYPD3, which is a putative cell surface binding partner of AGR2.

CONCLUSIONS

Our study provides novel, high-affinity, fully human, anti-AGR2 MAbs that neutralize the pro-tumor effects of extracellular AGR2 in PDAC.

Quantification of PD-L1 expression and tumor mutational burden in biologically distinct advanced pancreatic cancers responding to pembrolizumab: case reports

Background

The advent of checkpoint therapy is one of the most important recent advancements in cancer therapy. Though checkpoint therapy is a mainstay in some cancers, it has been largely ineffective in treating cancers of the pancreas. Pancreatic ductal adenocarcinoma and pancreatic neuroendocrine tumors are seldom responsive to checkpoint inhibition.

Case presentations

Here we present two cases of advanced pancreatic cancers that either failed to respond or recurred following conventional treatments. Tissue from each tumor was sequenced and analyzed for PD-L1 expression. Each patient was started on checkpoint blockade after assessing for a predictive biomarker, either the combined positive score or the tumor mutational burden. In each case, checkpoint blockade led to durable radiographic responses.

Conclusions

We therefore propose that it is reasonable to assess combined positive score and tumor mutational burden in refractory or recurrent pancreatic cancers when initiation of ICB is being considered.

Lynch Syndrome and Somatic Mismatch Repair Variants in Pancreas Cancer

Importance

Microsatellite (MS) instability (MSI-H) occurs frequently in Lynch syndrome (LS)-associated tumors and is associated with response to immune checkpoint blockade (ICB) therapy. MSI-H is conferred by germline or somatic variants in mismatch repair genes. The contribution of somatic oncogenesis to MSI-H in pancreatic cancer (PC) is unknown.

Objective

To evaluate an LS-related PC cohort to define clinicogenomic features, describe somatic MSI-H cases (germline negative), characterize response to ICB, and guide preferred MS testing methods.

Design, Setting, and Participants

This single-institution, retrospective analysis was conducted from March 2012 to July 2023 at Memorial Sloan Kettering Cancer Center and included 55 patients with PC and either an LS germline pathogenic variant (gPV) or somatic mismatch repair (MMR) variant.

Main Outcomes and Measures

Composite MMR and MS status determined using orthogonal methods. An artificial intelligence classifier was used to account for low-cellularity specimens. Demographic and clinical data were abstracted from medical record. Zygosity status and somatic comutation landscape analyzed.

Results

Fifty-five patients (23 women [42%]) had PC and an MMR variant: 32 (58%) had LS (LS cohort) and 23 (42%) had a somatic MMR variant (no germline pathogenic variant, somatic MMR cohort). In the LS cohort, 10 (31%) had gMSH2, 9 (28%) gMSH6, 8 (25%) gPMS2, 4 (13%) gMLH1, 1 (3%) gEPCAM. The median age at diagnosis was 68 years (range, 45-88 years). For composite MS status, 17 (59%) were MSI-H, 12 (41%) MS stable, and 3 MS unknown. Five cases were reclassified as MSI-H by the artificial intelligence classifier. In the somatic MMR cohort, 11 (48%) had MSH6, 7 (30%) MLH1, 3 (13%) MSH2, and 2 (9%) PMS2. The median age at diagnosis was 72 years (range, 66-85 years). For composite MS status, 10 (43%) were MSI-H, 11 (48%) MS stable, and 2 (9%) MS indeterminate. Six cases were reclassified as MSI-H by the artificial intelligence classifier. For the LS and somatic MMR cohorts, 20 received ICB (n = 17 MSI-H). The median ICB duration was 27.7 months (95% CI, 11.5 to not reached); the disease control rate was 80%.

Conclusion

The results of this cross-sectional study suggest that MSI-H occurs due to LS or somatic oncogenesis in PC. Orthogonal MS testing is key in PC; the artificial intelligence classifier reclassified approximately 20% of cases, most of which were low cellularity. ICB for patients with LS or somatic MSI-H PC provided significant benefit.

Prevalence and spectrum of germline pathogenic variants in cancer susceptibility genes among mexican patients with exocrine pancreatic cancer

BACKGROUND

Although universal germline genetic testing is recommended for patients with exocrine pancreatic cancer (PC), access to genetic testing remains limited in low- and middle-income countries. This study aims to narrow the gap in our understanding of the spectrum of germline pathogenic and likely pathogenic variants (PVs) in cancer susceptibility genes in the Mexican population.

METHODS

The landscape of PVs in cancer susceptibility genes was identified by next-generation sequencing multigene panel assays among patients with PC who were enrolled in the Clinical Cancer Genomics Community Research Network prospective registry in Mexico City.

RESULTS

From August 2019 to April 2023, 137 patients underwent genetic testing. The median age at diagnosis was 60 years (range 36-85), 58.4 % were women, and 38.7 % were metastatic at diagnosis. The frequency of germline PVs was 16 % (n = 22): ATM 36.4 % (n = 8), CDKN2A/p16INK4A 27.3 % (n = 6), BRCA2 9.1 % (n = 2), PALB2 9.1 % (n = 2), CHEK2 9.1 % (n = 2), TP53 4.5 % (n = 1), and NF1 4.5 % (n = 1). Additionally, 2 carriers of monoallelic germline variants in MUTYH were identified. No significant differences were observed between carriers and non-carriers in terms of family history of pancreatic cancer.

CONCLUSIONS

We identified a significant frequency of actionable germline PVs in Mexicans with PC, wherein the majority were in a broad spectrum of genes associated with the homologous recombination DNA repair mechanism. Most pancreatic cancer associated PVs were detected in non-BRCA genes, so our findings support the recommendation of multigene panel testing for genetic cancer risk assessment of Mexican individuals with PC.

Cytologic testing for mismatch repair deficiency/microsatellite instability and NTRK gene fusion is not routinely indicated in primary pancreaticobiliary carcinoma cell block material

INTRODUCTION

Pancreaticobiliary carcinomas rarely harbor targetable genetic alterations, including microsatellite instability (MSI) or neurotrophic tyrosine receptor kinase (NTRK) gene fusions. As these malignancies are typically present at an advanced stage and have suboptimal response to chemotherapy, the discovery of an actionable genomic alteration provides an additional avenue of treatment for chemotherapy-refractory cases.

MATERIALS AND METHODS

In this study, we evaluate 319 cases of pancreaticobiliary carcinoma diagnosed on fine-needle aspiration biopsy or biliary brushing for DNA mismatch repair (MMR) protein deficiency and pan-TRK overexpression by immunohistochemistry (IHC) and compare these results to MSI and NTRK gene fusion molecular testing.

RESULTS AND CONCLUSION

Although we find a high concordance between MMR protein IHC and MSI molecular testing in the evaluation of MMR deficiency and between pan-TRK IHC and NTRK fusion testing by next-generation sequencing, the low prevalence of either of these genetic alterations in our cohort casts doubt on the value of screening cases of pancreaticobiliary carcinoma for MMR protein deficiency and NTRK fusions.

Advancing Immunotherapy in Pancreatic Cancer

Pancreatic cancer remains one of the deadliest malignancies, with a consistently low five-year survival rate for the past several decades. This is in stark contrast to other cancers, which have seen significant improvement in survival and prognosis due to recent developments in therapeutic modalities. These modest improvements in pancreatic cancer outcomes have primarily resulted from minor advances in cytotoxic chemotherapeutics, with limited progress in other treatment approaches. A major focus of current therapeutic research is the further development of immunomodulatory therapies characterized by antibody-based approaches, cellular therapies, and vaccines. Although initial results utilizing immunotherapy in pancreatic cancer have been mixed, recent clinical trials have demonstrated significant improvements in patient outcomes. In this review, we detail these three approaches to immunomodulation, highlighting their common targets and distinct shortcomings, and we provide a narrative summary of completed and ongoing clinical trials that utilize these approaches to immunomodulation. Within this context, we aim to inform future research efforts by identifying promising areas that warrant further exploration.

Assessing Influence of Mismatch Repair Mutations on Survival in Patients After Resection of Pancreatic Ductal and Periampullary Adenocarcinoma

Background: Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related deaths in the United States. Previous studies have indicated that microsatellite instability and deficient mismatch repair (MMR) may be associated with improved survival in patients with pancreatic cancer. Here, we aim to investigate the impact of deficient MMR (dMMR) status on oncologic outcomes in patients after resection of PDAC and periampullary adenocarcinoma. Methods: This is a single-institution, retrospective study based on a prospectively maintained database. Pancreatic ductal adenocarcinoma (N = 342) and periampullary adenocarcinoma patients (N = 76) who underwent pancreatic resection surgery between 2016 and 2021 were included. Immunohistochemistry staining results of MMR proteins and next-generation sequencing data were recorded. Cancer-type dependent Cox regression analyses were performed to assess overall and disease-free survival, which was complemented with a 1:2 propensity-score matching for each of the cancer types in order to compare oncologic outcomes. Results: A total of 418 pancreatic cancer patients were included in the analysis. Fifteen patients (3.5%) were diagnosed as dMMR (PDAC N = 7 and periampullary adenocarcinoma N = 8). Cox regression modeling of dMMR status interaction with TNM staging and cancer type revealed that dMMR status strongly improves overall survival (p < 0.05). After propensity-score matching, Cox regression identified dMMR status as a significant marker of improved overall survival (HR = 0.27, 95%CI 0.09-0.88, p = 0.029). Conclusions: Overall, our findings suggest that dMMR status is associated with markedly improved survival outcomes in patients after resection of pancreatic and periampullary cancer. Future large-scale studies are needed to further validate this finding.

MSI-H Detection by ddPCR in Endoscopic Ultrasound Fine Needle Biopsy (EUS-FNB) from Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive disease with limited survival. Curative opportunities are only available for patients with resectable cancer. Palliative chemotherapy is the current standard of care for unresectable tumors. Numerous efforts have been made to investigate new therapeutic strategies for PDAC. Immunotherapy has been found to be effective in treating tumors with high microsatellite instability (MSI-H), including PDAC. The ability of the Endoscopic Ultrasound Fine Needle Biopsy (EUS-FNB) to reliably collect tissue could enhance new personalized treatment by permitting genomic alterations analysis. The aim of this study was to investigate the feasibility of obtaining adequate DNA for molecular analysis from EUS-FNB formalin-fixed-paraffin-embedded (FFPE) specimens. For this purpose, FFPE-DNA obtained from 43 PDAC archival samples was evaluated to verify adequacy in terms of quantity and quality and was tested to evaluate MSI-H status by droplet digital PCR (ddPCR). All samples were suitable for ddPCR analysis. Unlike the 1-2% MSI-H frequency found with traditional techniques, ddPCR detected this phenotype in 16.28% of cases. This study suggests the ddPCR ability to identify MSI-H phenotype, with the possibility of improving the selection of patients who may benefit from immunotherapy and who would be excluded by performing traditional diagnostic methods.

Fighting Pancreatic Cancer with a Vaccine-Based Winning Combination: Hope or Reality?

Pancreatic adenocarcinoma (PDA) represents the fourth leading cause of cancer-related mortality in the USA. Only 20% of patients present surgically resectable and potentially curable tumors at diagnosis, while 80% are destined for poor survival and palliative chemotherapy. Accordingly, the advancement of innovative and effective therapeutic strategies represents a pivotal medical imperative. It has been demonstrated that targeting the immune system represents an effective approach against several solid tumors. The immunotherapy approach encompasses a range of strategies, including the administration of antibodies targeting checkpoint molecules (immune checkpoint inhibitors, ICIs) to disrupt tumor suppression mechanisms and active immunization approaches that aim to stimulate the host's immune system. While vaccines have proved effective against infectious agents, vaccines for cancer remain an unfulfilled promise. Vaccine-based therapy targeting tumor antigens has the potential to be a highly effective strategy for initiating and maintaining T cell recognition, enhancing the immune response, and ultimately promoting cancer treatment success. In this review, we examined the most recent clinical trials that employed diverse vaccine types to stimulate PDA patients' immune systems, either independently or in combination with chemotherapy, radiotherapy, ICIs, and monoclonal antibodies with the aim of ameliorating PDA patients' quality of life and extend their survival.

Systemic Therapy for Metastatic Pancreatic Cancer-Current Landscape and Future Directions

Pancreatic ductal adenocarcinoma (PDAC) is a significant cause of cancer-associated mortality, with a rising global incidence. A paucity of strong predictive risk factors mean screening programmes are difficult to implement. Historically, a lack of identifiable and actionable driver mutations, coupled with a relatively immunosuppressed tumour microenvironment, has led to a reliance on cytotoxic chemotherapy. The NAPOLI-3 trial has reported data supporting consideration of NALIRIFOX as a new first-line standard of care. Kirsten Rat Sarcoma Virus (KRAS) G12D mutations are present in >90% of all PDAC's; exciting breakthroughs in small molecule inhibitors targeting KRAS G12D may open new modalities of treatment, and therapies targeting multiple KRAS mutations are also in early clinical trials. Although immunotherapy strategies to date have been disappointing, combination with chemotherapy and/or small molecule inhibitors hold promise and warrant further exploration.

Pancreas Fine Needle Aspiration: Current and Future Impact on Patient Care

Pancreatic lesions can be solid or cystic and comprise a wide range of benign, premalignant, and malignant entities. Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is the current primary sampling method for the preoperative diagnosis of pancreatic lesions. Optimal handling of cytology/small tissue specimens is critical to ensure that the often-scant diagnostic material is appropriately utilized for ancillary and/or molecular studies when appropriate. Ultimately, evaluation of EUS-FNA cytology and small biopsy material can provide accurate and timely diagnoses to guide patient management and triage them to surveillance or surgical intervention.

Complete pathological response to pembrolizumab in pretreated pancreatic acinar cell carcinoma

BACKGROUND

Therapeutic approach used for pancreatic ductal adenocarcinoma is usually translated also for the rarer acinar counterpart, which shows a different mutational landscape nevertheless. While dMMR/MSI-H status is rare in the ductal histotype, it appears to be more prevalent in pancreatic acinar cell carcinoma (PACC).

CASE PRESENTATION

We report the case of a patient with locally advanced MSI-H PACC in whom the treatment with the anti-PD-1 pembrolizumab, administered as third line, made possible surgical resection, achieving even an exceptional pathological complete response.

CONCLUSIONS

Treatment of PACC should be tailored based on the peculiar molecular features that distinguish PACC from ductal adenocarcinoma. Evaluation of potentially therapeutically targetable alterations should be mandatory in case of PACC diagnosis.

Familial Intraductal Papillary Mucinous Neoplasm Associated With the Germline MSH6 Missense Variant and Progression of Pancreatic cancer

OBJECTIVES

Intraductal papillary mucinous neoplasm (IPMN) in individuals with at least one first-degree relative with IPMN is defined as familial IPMN. However, few studies have reported on familial IPMN, its clinical characteristics, or the associated genetic factors.

MATERIALS AND METHODS

We report the case of a 58-year-old woman with multifocal IPMN and a mural nodule in the pancreatic body. The patient underwent a distal pancreatectomy and developed pancreatic head cancer 1 year and 6 months postoperatively. The patient had a family history of multifocal IPMN in her father. Therefore, a genetic predisposition to IPMN and pancreatic cancer was suspected. The patient was analyzed for germline variants, and the resected IPMN was subjected to immunohistochemical and somatic variant analyses.

RESULTS

Next-generation sequencing revealed a heterozygous germline missense variant in exon 5 of MSH6 (c.3197A>G; Tyr1066Cys). The pathogenicity of this variant of uncertain significance was suspected based on multiple in silico analyses, and the same MSH6 variant was identified in the patient's father's colonic adenoma. The mural nodule in the pancreatic body was pathologically diagnosed as a high-grade IPMN with ossification and somatic KRAS and PIK3CA variants.

CONCLUSIONS

This case revealed a possible genetic factor for familial IPMN development and presented interesting clinicopathological findings.

State of the art: Targeting microsatellite instability in gastrointestinal cancers

DNA mismatch repair (MMR) deficiency and the associated microsatellite instability (MSI) phenotype has become a subject of enormous interest in recent years due to the demonstrated efficacy of immune checkpoint inhibitors (ICI) in advanced tumours. Assessing MSI in patients with gastrointestinal tract (GI) cancers is useful to exclude Lynch syndrome, but also to predict benefit for ICI. Following review of the relevant literature, this review article aims to outline the clinicopathologic spectrum of MSI and mismatch repair deficiency (dMMR) in the GI tract, hepatobiliary system and pancreas and discuss the therapeutic consideration in this disease.

Personalized Medicine in Pancreatic Cancer: The Promise of Biomarkers and Molecular Targeting with Dr. Michael J. Pishvaian

Pancreatic cancer, with its alarming rising incidence, is predicted to become the second deadliest type of solid tumor by 2040, highlighting the urgent need for improved diagnostic and treatment strategies. Despite medical advancements, the five-year survival rate for pancreatic cancer remains about 14%, dropping further when metastasized. This review explores the promise of biomarkers for early detection, personalized treatment, and disease monitoring. Molecular classification of pancreatic cancer into subtypes based on genetic mutations, gene expression, and protein markers guides treatment decisions, potentially improving outcomes. A plethora of clinical trials investigating different strategies are currently ongoing. Targeted therapies, among which those against CLAUDIN 18.2 and inhibitors of Claudin 18.1, have shown promise. Next-generation sequencing (NGS) has emerged as a powerful tool for the comprehensive genomic analysis of pancreatic tumors, revealing unique genetic alterations that drive cancer progression. This allows oncologists to tailor therapies to target specific molecular abnormalities. However, challenges remain, including limited awareness and uptake of biomarker-guided therapies. Continued research into the molecular mechanisms of pancreatic cancer is essential for developing more effective treatments and improving patient survival rates.

Frequency-dependent selection of neoantigens fosters tumor immune escape and predicts immunotherapy response

Cancer is an evolutionary process shaped by selective pressure from the microenvironments. However, recent studies reveal that certain tumors undergo neutral evolution where there is no detectable fitness difference amongst the cells following malignant transformation. Here, through computational modeling, we demonstrate that negative frequency-dependent selection (or NFDS), where the immune response against cancer cells depends on the clonality of neoantigens, can lead to an immunogenic landscape that is highly similar to neutral evolution. Crucially, NFDS promotes high antigenic heterogeneity and early immune evasion in hypermutable tumors, leading to poor responses to immune checkpoint blockade (ICB) therapy. Our model also reveals that NFDS is characterized by a negative association between average clonality and total burden of neoantigens. Indeed, this unique feature of NFDS is common in the whole-exome sequencing (WES) datasets (357 tumor samples from 275 patients) from four melanoma cohorts with ICB therapy and a non-small cell lung cancer (NSCLC) WES dataset (327 tumor samples from 100 patients). Altogether, our study provides quantitative evidence supporting the theory of NFDS in cancer, explaining the high prevalence of neutral-looking tumors. These findings also highlight the critical role of frequency-dependent selection in devising more efficient and predictive immunotherapies.

Contemporary Approaches to Immunotherapy of Solid Tumors

In recent years, the arrival of the immunotherapy industry has introduced the possibility of providing transformative, durable, and potentially curative outcomes for various forms of malignancies. However, further research has shown that there are a number of issues that significantly reduce the effectiveness of immunotherapy, especially in solid tumors. First of all, these problems are related to the protective mechanisms of the tumor and its microenvironment. Currently, major efforts are focused on overcoming protective mechanisms by using different adoptive cell therapy variants and modifications of genetically engineered constructs. In addition, a complex workforce is required to develop and implement these treatments. To overcome these significant challenges, innovative strategies and approaches are necessary to engineer more powerful variations of immunotherapy with improved antitumor activity and decreased toxicity. In this review, we discuss recent innovations in immunotherapy aimed at improving clinical efficacy in solid tumors, as well as strategies to overcome the limitations of various immunotherapies.

Mutations in Mismatch Repair Genes and Microsatellite Instability Status in Pancreatic Cancer

Patients with pancreatic cancer (PC) showing mismatch repair (MMR) deficiency may benefit from immunotherapy. Microsatellite instability (MSI) is a hallmark of MMR deficiency (MMR-D). Here, we estimated the prevalence of MSI in PC, investigated germline and somatic mutations in the three MMR genes (MLH1, MSH2, and MSH6), and assessed the relationship between MMR genes mutations and MSI status in PC. Clinical specimens from PC patients were analyzed using targeted next-generation sequencing, including paired normal and tumor specimens from 155 patients, tumor-only specimens from 86 patients, and normal-only specimens from 379 patients. The MSI status of 235 PCs was assessed via PCR. Pathogenic/likely pathogenic (P/LP) germline variants in the MMR genes were identified in 1.1% of patients, while somatic variants were found in 2.6% of patients. No MSI-H tumors were detected. One patient carried two variants (P (VAF = 0.57) and LP (VAF = 0.25)) simultaneously; however, their germline/somatic status remains unknown due to the investigation focusing solely on the tumor and MSI analysis was not performed for this patient. MSI is rare in PC, even in tumors with MMR genes mutations. Our findings underscore the importance of assessing tumor MMR-D status in PC patients with confirmed Lynch syndrome when deciding whether to prescribe immunotherapy.

The role of germline BRCA1 & BRCA2 mutations in familial pancreatic cancer: A systematic review and meta-analysis

BACKGROUND

Familial Pancreatic Cancer (FPC) presents a notable risk, with 3-10% of pancreatic adenocarcinoma cases having a family history. Studies link FPC to syndromes like HBOC, suggesting BRCA1/BRCA2 mutations play a role. BRCA gene functions in DNA repair impact FPC management, influencing sensitivity to therapies like PARP inhibitors. Identifying mutations not only aids FPC treatment but also reveals broader cancer risks. However, challenges persist in selectively applying genetic testing due to cost constraints. This Systematic Review focuses on BRCA1/BRCA2 significance in FPC, diagnostic criteria, prognostic value, and limitations.

METHOD

Original articles published from 2013 to January 2023 were sourced from databases such as Scopus, PubMed, ProQuest, and ScienceDirect. Inclusion criteria comprised observational cohort or diagnostic studies related to the role of BRCA1/2 mutation in correlation to familial pancreatic cancer (FPC), while article reviews, narrative reviews, and non-relevant content were excluded. The assessment of bias used ROBINS-I, and the results were organized using PICOS criteria in a Google spreadsheet table. The systematic review adhered to the PRISMA 2020 checklist.

RESULT

We analyzed 9 diagnostic studies encompassing 1325 families and 4267 patients from Italy, USA, and Poland. Despite the limitation of limited homogenous PICO studies, our findings effectively present evidence. BRCA1/2 demonstrates benefits in detecting first-degree relatives FPC involvement with 2.26-10 times higher risk. These mutation findings also play an important role since with the BRCA1/2 targeted therapy, Poly-ADP Ribose Polymerase inhibitors (PARP) may give better outcomes of FPC treatment. Analysis of BRCA1 and BRCA2 administration's impact on odds ratio (OR) based on six and five studies respectively. BRCA1 exhibited non-significant effects (OR = 1.26, P = 0.51), while BRCA2 showed significance (OR = 1.68, P = 0.04). No heterogeneity observed, indicating consistent results. Further research on BRCA1 is warranted.

CONCLUSION

Detecting the BRCA1/2 mutation gene offers numerous advantages, particularly in its correlation with FPC. For diagnostic and prognostic purposes, testing is strongly recommended for first-degree relatives, who face a significantly higher risk (2.26-10 times) of being affected. Additionally, FPC patients with identified BRCA1/2 mutations exhibit a more favorable prognosis compared to the non-mutated population. This is attributed to the availability of targeted BRCA1/2 therapy, which maximizes treatment outcomes.

Molecular Characterization and Therapeutic Opportunities in KRAS Wildtype Pancreatic Ductal Adenocarcinoma

PURPOSE

To investigate the molecular characteristics of and potential for precision medicine in KRAS wildtype pancreatic ductal adenocarcinoma (PDAC).

PATIENTS AND METHODS

We investigated 27 patients with KRASWT PDAC at our institution. Clinical data were obtained via chart review. Tumor specimens for each subject were interrogated for somatic single nucleotide variants, insertion and deletions, and copy number variants by DNA sequencing. Gene fusions were detected from RNA-seq. A patient-derived organoid (PDO) was developed from a patient with a MET translocation and expanded ex vivo to predict therapeutic sensitivity prior to enrollment in a phase 2 clinical trial.

RESULTS

Transcriptomic analysis showed our cohort may be stratified by the relative gene expression of the KRAS signaling cascade. The PDO derived from our patient harboring a TFG-MET rearrangement was found to have in vitro sensitivity to the multi-tyrosine kinase inhibitor crizotinib. The patient was enrolled in the phase 2 SPARTA clinical trial and received monotherapy with vebrelitinib, a c-MET inhibitor, and achieved a partial and durable response.

CONCLUSIONS

KRASWT PDAC is molecularly distinct from KRASMUT and enriched with potentially actionable genetic variants. In our study, transcriptomic profiling revealed that the KRAS signaling cascade may play a key role in KRASWT PDAC. Our report of a KRASWT PDAC patient with TFG-MET rearrangement who responded to a cMET inhibitor further supports the pursuit of precision oncology in this sub-population. Identification of targetable mutations, perhaps through approaches like RNA-seq, can help enable precision-driven approaches to select optimal treatment based on tumor characteristics.

PD-L1 expression in pancreaticobiliary adenosquamous carcinoma: a single-institution case series

Background

The programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway is a potent negative regulator of T-cell-mediated immune response that is upregulated in many neoplasms. Pancreaticobiliary adenosquamous carcinoma (PB-ASC) is an aggressive cancer that carries a poorer prognosis compared with pure pancreaticobiliary adenocarcinoma (PB-AC). To date, there is little published information regarding PD-L1 expression in PB-ASC. The aim of the study was to examine the relationship between PD-L1 expression and tumor-infiltrating lymphocytes in PB-ASC and PB-AC.

Methods

We evaluated 15 PB-ASCs (10 pancreatic, 5 gallbladder) and 34 control PB-ACs (22 pancreatic ductal, and 12 gallbladder) for tumor expression of PD-L1 using anti-PD-L1 (E1L3N) antibody. All tumors were classified into three immune phenotypes: immune inflamed (II), immune excluded (IE), and immune desert (ID) according to the distribution of tumor-infiltrating lymphocytes in tumor tissues.

Results

The frequency of PD-L1 expression was significantly higher in PB-ASC (10/15; 66.7%) than in PB-AC (3/34; 8.8%). In PB-ASC, PD-L1 expression occurred exclusively in the squamous component in six cases, exclusively in the glandular component in one case, and in both the squamous and the glandular components in three cases. PD-L1 expression in PB-ASC was irrespective of the tumor immune status, whereas its expression in PB-AC was observed only in tumors with the II or IE phenotype. The ID phenotype was relatively rare (4/15; 26.7%) in PB-ASC compared with PB-AC (22/34; 65%; P=0.02).

Conclusions

PB-ASCs are notably enriched in inflammatory response and showed significantly higher PD-L1 expression than PB-AC (P<0.001), suggesting a potential therapeutic role for immune checkpoint inhibitors in managing patients with PB-ASC.

Tofacitinib to prevent anti-drug antibody formation against LMB-100 immunotoxin in patients with advanced mesothelin-expressing cancers

Background

LMB-100 is a mesothelin (MSLN)-targeting recombinant immunotoxin (iTox) carrying a Pseudomonas exotoxin A payload that has shown promise against solid tumors, however, efficacy is limited by the development of neutralizing anti-drug antibodies (ADAs). Tofacitinib is an oral Janus Kinase (JAK) inhibitor that prevented ADA formation against iTox in preclinical studies.

Methods

A phase 1 trial testing LMB-100 and tofacitinib in patients with MSLN-expressing cancers (pancreatic adenocarcinoma, n=13; cholangiocarcinoma, n=1; appendiceal carcinoma, n=1; cystadenocarcinoma, n=1) was performed to assess safety and to determine if tofacitinib impacted ADA formation. Participants were treated for up to 3 cycles with LMB-100 as a 30-minute infusion on days 4, 6, and 8 at two dose levels (100 and 140 µg/kg) while oral tofacitinib was administered for the first 10 days of the cycle (10 mg BID). Peripheral blood was collected for analysis of ADA levels, serum cytokines and circulating immune subsets.

Results

The study was closed early due to occurrence of drug-induced pericarditis in 2 patients. Pericarditis with the combination was not reproducible in a transgenic murine model containing human MSLN. Two of 4 patients receiving all 3 cycles of treatment maintained effective LMB-100 levels, an unusual occurrence. Sustained increases in systemic IL-10 and TNF-α were seen, a phenomenon not observed in prior LMB-100 studies. A decrease in activated T cell subsets and an increase in circulating immunosuppressive myeloid populations occurred. No radiologic decreases in tumor volume were observed.

Discussion

Further testing of tofacitinib to prevent ADA formation is recommended in applicable non-malignant disease settings.

Clinical trial registration

https://www.clinicaltrials.gov/study/NCT04034238.

Tissue processing of endoscopic ultrasound-guided fine-needle aspiration specimens from solid pancreatic lesions

Now that tissue cores can be obtained using fine-needle biopsy (FNB) needles, the ways tissues are handled for endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) are changing. Direct smear, touch smear of core tissues, and centrifugation have been used for cytological examinations, and liquid-based cytology (LBC), which allows immunostaining and genetic tests that use residual samples, is emerging as an alternative. We emphasize that liquid cytology (Cytospin™ cytology and LBC) is still important, because it enables the diagnosis of pancreatic ductal adenocarcinoma (PDAC) when cancerous cells are scarce in specimens. Cell blocks are being replaced by core tissues obtained via FNB needles. Recent reports indicate that rapid on-site evaluation (ROSE) is not necessary when FNB needles are used, and macroscopic on-site evaluation is used to evaluate specimen adequacy. Macroscopic findings of specimens are helpful in the diagnostic workup and for clarifying specimen-handling methods. In addition to the red strings and white cores observed in PDAC, mixed red and white strings, gray tissues, and gelatinous tissues are observed. Gray (necrotic) tissues and gelatinous (mucus) tissues are more suitable than histology for cell block or cytological processing. Tumor cells in neuroendocrine tumors (NETs) are numerous in red strings but cannot be observed macroscopically. ROSE might thus be necessary for lesions that may be NETs. Core tissues can be used for genetic tests, such as those used for KRAS mutations and comprehensive genomic profiling. Cytological materials, including slides and LBC specimens, can also be genetic test materials.

The relationship between DNA mismatch repair gene and other prognostic parameters in pancreatic adenocarcinoma

The aim of the study was to determine DNA mismatch repair (MMR) proteins by immunohistochemically using MLH1, MSH2, MSH6, and PMS2 antibodies in patients diagnosed as pancreatic ductal adenocarcinoma and to assess its relationship with histopathological and clinical prognostic parameters. Fifty cases with a diagnosis of pancreatic ductal adenocarcinoma who underwent surgical resection, were included in the study. Demographic and histopathological features of the patients were collected from the medical records. The relationships between microsatellite status and prognostic parameters were determined. The mean age of the patients was 66.5 ± 9.5 years (range: 47-87) and male/female ratio was 1.63 (31/19). No errors were detected in DNA MMR proteins in any of the cases, and were classified as microsatellite stable. The mean tumor diameter was 4.01 ± 1.77 cm and 74% of the tumors were localized in the pancreatic head. All of the cases had lymphatic invasion, whereas vascular invasion was detected in only 78% and perineural invasion in 98% of the patients. When the relationship between prognostic parameters and survival was evaluated, statistically significant correlation was observed in patient age and histopathological parameters such as tumor diameter, status of surgical margins, and vascular invasion (p < 0.05). Age, tumor size, presence of tumor at surgical margins, vascular invasion, and adjuvant treatment were correlated with survival. Although microsatellite instability was not detected in our cases, it is important to determine the microsatellite status by immunohistochemistry for predicting the chemotherapy response and determining the immunotherapy option in pancreatic adenocarcinomas.

Spectrum of somatic mutational features of colorectal tumors in ancestrally diverse populations

Ancestrally diverse and admixed populations, including the Hispanic/Latino/a/x/e community, are underrepresented in cancer genetic and genomic studies. Leveraging the Latino Colorectal Cancer Consortium, we analyzed whole exome sequencing data on tumor/normal pairs from 718 individuals with colorectal cancer (128 Latino, 469 non-Latino) to map somatic mutational features by ethnicity and genetic ancestry. Global proportions of African, East Asian, European, and Native American ancestries were estimated using ADMIXTURE. Associations between global genetic ancestry and somatic mutational features across genes were examined using logistic regression. TP53 , APC , and KRAS were the most recurrently mutated genes. Compared to non-Latino individuals, tumors from Latino individuals had fewer KRAS (OR=0.64, 95%CI=0.41-0.97, p=0.037) and PIK3CA mutations (OR=0.55, 95%CI=0.31-0.98, p=0.043). Genetic ancestry was associated with presence of somatic mutations in 39 genes (FDR-adjusted LRT p<0.05). Among these genes, a 10% increase in African ancestry was associated with significantly higher odds of mutation in KNCN (OR=1.34, 95%CI=1.09-1.66, p=5.74×10 -3 ) and TMEM184B (OR=1.53, 95%CI=1.10-2.12, p=0.011). Among RMGs, we found evidence of association between genetic ancestry and mutation status in CDC27 (LRT p=0.0084) and between SMAD2 mutation status and AFR ancestry (OR=1.14, 95%CI=1.00-1.30, p=0.046). Ancestry was not associated with tumor mutational burden. Individuals with above-average Native American ancestry had a lower frequency of microsatellite instable (MSI-H) vs microsatellite stable tumors (OR=0.45, 95%CI=0.21-0.99, p=0.048). Our findings provide new knowledge about the relationship between ancestral haplotypes and somatic mutational profiles that may be useful in developing precision medicine approaches and provide additional insight into genomic contributions to cancer disparities.

Significance

Our data in ancestrally diverse populations adds essential information to characterize mutational features in the colorectal cancer genome. These results will help enhance equity in the development of precision medicine strategies.

High hypoxia status in pancreatic cancer is associated with multiple hallmarks of an immunosuppressive tumor microenvironment

Introduction

Pancreatic ductal adenocarcinoma (PDAC), the most common form of pancreatic cancer, is a particularly lethal disease that is often diagnosed late and is refractory to most forms of treatment. Tumour hypoxia is a key hallmark of PDAC and is purported to contribute to multiple facets of disease progression such as treatment resistance, increased invasiveness, metabolic reprogramming, and immunosuppression.

Methods

We used the Buffa gene signature as a hypoxia score to profile transcriptomics datasets from PDAC cases. We performed cell-type deconvolution and gene expression profiling approaches to compare the immunological phenotypes of cases with low and high hypoxia scores. We further supported our findings by qPCR analyses in PDAC cell lines cultured in hypoxic conditions.

Results

First, we demonstrated that this hypoxia score is associated with increased tumour grade and reduced survival suggesting that this score is correlated to disease progression. Subsequently, we compared the immune phenotypes of cases with high versus low hypoxia score expression (HypoxiaHI vs. HypoxiaLOW) to show that high hypoxia is associated with reduced levels of T cells, NK cells and dendritic cells (DC), including the crucial cDC1 subset. Concomitantly, immune-related gene expression profiling revealed that compared to HypoxiaLOW tumours, mRNA levels for multiple immunosuppressive molecules were notably elevated in HypoxiaHI cases. Using a Random Forest machine learning approach for variable selection, we identified LGALS3 (Galectin-3) as the top gene associated with high hypoxia status and confirmed its expression in hypoxic PDAC cell lines.

Discussion

In summary, we demonstrated novel associations between hypoxia and multiple immunosuppressive mediators in PDAC, highlighting avenues for improving PDAC immunotherapy by targeting these immune molecules in combination with hypoxia-targeted drugs.

REV7 is involved in outcomes of platinum-based chemotherapy in pancreatic cancer by controlling the DNA damage response

REV7 is a multifunctional protein implicated in various biological processes, including DNA damage response. REV7 expression in human cancer cells affects their sensitivity to DNA-damaging agents. In the present study, we investigated the significance of REV7 in pancreatic ductal adenocarcinoma (PDAC). REV7 expression was immunohistochemically examined in 92 resected PDAC specimens and 60 endoscopic ultrasound-guided fine-needle aspiration biopsy (EUS-FNAB) specimens of unresectable PDAC treated with platinum-based chemotherapy, and its association with clinicopathologic features was analyzed. Although REV7 expression was not significantly associated with the progression of primary tumors (T-factor and Stage) in either resected or unresectable PDAC, decreased levels of REV7 expression in EUS-FNAB specimens of unresectable PDAC were significantly associated with better outcomes of platinum-based chemotherapy and a favorable prognosis. REV7-deficient PDAC cell lines showed suppressed cell growth and enhanced sensitivity to cisplatin in vitro. Tumor-bearing mice generated using REV7-deficient PDAC cell lines also showed enhanced sensitivity to cisplatin in vivo. RNA sequencing analysis using WT and REV7-deficient PDAC cell lines revealed that REV7 inactivation promoted the downregulation of genes involved in the DNA repair and the upregulation of genes involved in apoptosis. Our results indicate that decreased expression of REV7 is associated with better outcomes of platinum-based chemotherapy in PDAC by suppressing the DNA damage response. It is also suggested that REV7 is a useful biomarker for predicting the outcome of platinum-based chemotherapy and the prognosis of unresectable PDAC and is a potential target for PDAC treatment.

Genomic profile and clinical features of MSI-H and TMB-high pancreatic cancers: real-world data from C-CAT database

BACKGROUND

Microsatellite instability high (MSI-H) and tumor mutational burden high (TMB-high) pancreatic cancer are rare, and information is lacking. Based on the C-CAT database, we analyzed the clinical and genomic characteristics of patients with these subtypes.

METHODS

We retrospectively reviewed data on 2206 patients with unresectable pancreatic adenocarcinoma enrolled in C-CAT between July 2019 and January 2022. The clinical features, proportion of genomic variants classified as oncogenic/pathogenic in C-CAT, overall response rate (ORR), disease control rate (DCR), and time to treatment failure (TTF) of chemotherapy as first-line treatment were evaluated.

RESULTS

Numbers of patients with MSI-H and TMB-high were 7 (0.3%) and 39 (1.8%), respectively. All MSI-H patients were TMB-high. MSI-H and TMB-high patients harbored more mismatch repair genes, such as MSH2, homologous recombination-related genes, such as ATR and BRCA2, and other genes including BRAF, KMT2D, and SMARCA4. None of the 6 MSI-H patients who received chemotherapy achieved a clinical response, including 4 patients treated with gemcitabine plus nab-paclitaxel (GnP) therapy, whose DCR was significantly lower than that of microsatellite stable (MSS) patients (0 vs. 67.0%, respectively, p = 0.01). Among the TMB-high and TMB-low groups, no significant differences were shown in ORR, DCR (17.1 vs. 23.1% and 57.1 vs. 63.1%, respectively), or median TTF (25.9 vs. 28.0 weeks, respectively) of overall first-line chemotherapy.

CONCLUSIONS

MSI-H and TMB-high pancreatic cancers showed some distinct genomic and clinical features from our real-world data. These results suggest the importance of adapting optimal treatment strategies according to the genomic alterations.

Gastrointestinal Malignancy: Genetic Implications to Clinical Applications

Advances in molecular genetics have revolutionized our understanding of the pathogenesis, progression, and therapeutic options for treating gastrointestinal (GI) cancers. This chapter provides a comprehensive overview of the molecular landscape of GI cancers, focusing on key genetic alterations implicated in tumorigenesis across various anatomical sites including GIST, colon and rectum, and pancreas. Emphasis is placed on critical oncogenic pathways, such as mutations in tumor suppressor genes, oncogenes, chromosomal instability, microsatellite instability, and epigenetic modifications. The role of molecular biomarkers in predicting prognosis, guiding treatment decisions, and monitoring therapeutic response is discussed, highlighting the integration of genomic profiling into clinical practice. Finally, we address the evolving landscape of precision oncology in GI cancers, considering targeted therapies and immunotherapies.

Immunotherapy in Gastrointestinal Cancers

Immunotherapy has revolutionised cancer treatment over the past decade. Long-term durable responses can be achieved in some cancer patient populations that were previously facing terminal disease. In this chapter, we summarise current phase 3 clinical trial evidence for the use of immunotherapy in gastrointestinal cancers (oesophageal squamous cell carcinoma, oesophago-gastric adenocarcinoma, pancreatic cancer, biliary cancer, hepatocellular carcinoma, colorectal cancer, and squamous cell cancer of the anus). We discuss meaningful biomarkers used in clinical trials to select patients most likely to benefit from immunotherapy, such as mismatch-repair deficiency (MMRd)/microsatellite instability (MSI) and programmed-death-ligand-1 (PD-L1) immunohistochemistry (IHC) expression. Clinical questions are arising regarding the role of immunotherapy in the adjuvant/perioperative setting, optimal timing of surgery in patients who respond to immunotherapy, and toxicities specific to patients with gastrointestinal malignancies. We outline the current landscape and future horizon of immunotherapy in gastrointestinal cancers, such as strategies to increase effectiveness of checkpoint blockade through combinations with other checkpoint inhibitors, cytotoxic chemotherapy, targeted agents, radiotherapy, CAR-T therapy, and cancer vaccines.

Therapeutic developments in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) has a rising incidence and is one of the most lethal human malignancies. Much is known regarding the biology and pathophysiology of PDAC, but translating this knowledge to the clinic to improve patient outcomes has been challenging. In this Review, we discuss advances and practice-changing trials for PDAC. We briefly review therapeutic failures as well as ongoing research to refine the standard of care, including novel biomarkers and clinical trial designs. In addition, we highlight contemporary areas of research, including poly(ADP-ribose) polymerase inhibitors, KRAS-targeted therapies and immunotherapies. Finally, we discuss the future of pancreatic cancer research and areas for improvement in the next decade.

An overview of up-and-coming immune checkpoint inhibitors for pancreatic cancer

INTRODUCTION

Immune checkpoint inhibitors (ICIs) targeting programmed cell death protein-1 (PD-1/PD-L1) pathway as well as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) have demonstrated substantial potential in several malignancies. Pancreatic adenocarcinoma (PC) still carries a high mortality despite tremendous advances in the anti-cancer arsenal.

AREAS COVERED

In this review, we discuss completed and ongoing studies on various ICIs in PC. ICIs have not yielded significant benefits as monotherapy. However, the combination with currently utilized therapies as well as with several other newer forms of therapy has delineated encouraging results. Larger trials are currently underway to definitively characterize the utility of ICIs in the treatment algorithm of PC. ICIs are approved for cancers with mismatch repair deficiency (dMMR) or microsatellite instability-high tumors (MSI-H) as a tumor-agnostic treatment strategy usually referred to as hot tumors.

EXPERT OPINION

Studies evaluating different drugs to transform the tumor microenvironment (TME) from 'cold' to 'hot' have not shown promise in PC. There still needs to be more prospective trials evaluating the efficacy of the combination of ICIs with different therapeutic modalities in PC that can augment the immunogenic potential of those 'cold' tumors. Exploratory biomarker analysis may help us identify those subsets of PC patients who may particularly benefit from ICIs.

Current status and perspectives of genetic testing in gastrointestinal cancer (Review)

Genetic testing has become widespread in daily medical care for gastrointestinal (GI) cancers. However, unlike breast cancer and non-small cell lung cancer, in which personalized medicine targeting various driver genes is standardized, the incidence of targeted gene abnormalities in GI cancers is low. Nevertheless, such abnormalities may be linked to therapeutic agents and the further development of therapeutic agents for personalized medicine for GI cancers is desired. A liquid biopsy is of great benefit in offering clinical decision support, in applications such as GI cancer screening, surgical interventions, monitoring disease status and enhancing patient survival outcomes, all of which would contribute to personalized medicine. Germline genetic testing is required for several types of GI cancer, which shows clinical indications of hereditary predisposition. The increasing use of multigene panel testing has redefined gene-cancer associations, and consequently the estimate of cancer risk that vary from low to high penetrance. Comprehensive genetic testing can enable the detection of novel treatment targets and the discovery of undefined multiple diagnostic/predictive markers, which may enhance the molecular-level understanding of GI cancers. Genetic testing can also aid the design of more appropriate and adequate genomic-driven therapies for patients who may benefit from other standardized therapeutic methods.

Establishment and Thorough Characterization of Xenograft (PDX) Models Derived from Patients with Pancreatic Cancer for Molecular Analyses and Chemosensitivity Testing

Patient-derived xenograft (PDX) tumor models are essential for identifying new biomarkers, signaling pathways and novel targets, to better define key factors of therapy response and resistance mechanisms. Therefore, this study aimed at establishing pancreas carcinoma (PC) PDX models with thorough molecular characterization, and the identification of signatures defining responsiveness toward drug treatment. In total, 45 PC-PDXs were generated from 120 patient tumor specimens and the identity of PDX and corresponding patient tumors was validated. The majority of engrafted PDX models represent ductal adenocarcinomas (PDAC). The PDX growth characteristics were assessed, with great variations in doubling times (4 to 32 days). The mutational analyses revealed an individual mutational profile of the PDXs, predominantly showing alterations in the genes encoding KRAS, TP53, FAT1, KMT2D, MUC4, RNF213, ATR, MUC16, GNAS, RANBP2 and CDKN2A. Sensitivity of PDX toward standard of care (SoC) drugs gemcitabine, 5-fluorouracil, oxaliplatin and abraxane, and combinations thereof, revealed PDX models with sensitivity and resistance toward these treatments. We performed correlation analyses of drug sensitivity of these PDX models and their molecular profile to identify signatures for response and resistance. This study strongly supports the importance and value of PDX models for improvement in therapies of PC.