Fusion genes in pancreatic tumors

Gene fusions and rearrangements play a crucial role in tumor biology. They are rare events typically detected in KRAS wild-type (WT) pancreatic tumors. Their identification can inform clinical management by enabling precision oncology, as fusions involving BRAF, FGFR2, RET, NTRK, NRG1, and ALK represent actionable targets in KRAS-WT cancers, and serve diagnostic purposes since fusions involving PRKACA/B represent the diagnostic hallmark of intraductal oncocytic papillary neoplasms (IOPNs). Although they are rare, the therapeutic and diagnostic importance of these genomic events should not be underestimated, highlighting the need for quality-ensured molecular diagnostics in the management of cancer. Herein we review the existing literature on the role of fusion genes in pancreatic tumors and their clinical potential as effective biomarkers and therapeutic targets.

Genomic determinants of biological aggressiveness and poor prognosis of pancreatic cancers: KRAS and beyond

INTRODUCTION

A marked histomolecular heterogeneity characterizes pancreatic cancer. Thus, different tumor histologies with divergent genomic profiles exist within the same category.

AREAS COVERED

Using data from PubMed, SCOPUS, and Embase (last search date: 04/04/2024), this expert-based, narrative review presents and discusses the essential molecular determinants of biological aggressiveness and poor prognosis in pancreatic cancer. First, KRAS mutation still represents one of the most critical difficulties in treating pancreatic cancers. In this district, it is mutated in > 90% of malignant tumors. Notably, actionable alterations for molecular-based therapies are typically lacking in KRAS-mutated pancreatic cancer. Furthermore, transcriptome-based studies clarified that the squamous phenotype is characterized by poorer prognosis and response to standard chemotherapy. We also discuss molecular biomarkers related to dismal prognosis in specific subsets of pancreatic cancer, such as SMAD4 in signet-ring cell carcinoma and TP53 in invasive cancers derived from intraductal tubulopapillary neoplasms.

EXPERT OPINION

The identification of the subgroups of pancreatic cancer with particularly unfavorable prognoses is a critical step for addressing specific research efforts. In addition to implementing and strengthening current precision oncology strategies, the decisive step for improving the survival of patients affected by pancreatic cancer must pass through targeting the KRAS gene.

Molecular and Phenotypic Profiling for Precision Medicine in Pancreatic Cancer: Current Advances and Future Perspectives

Pancreatic cancer is the most common lethal malignancy, with little improvement in patient outcomes over the decades. The development of early detection methods and effective therapeutic strategies are needed to improve the prognosis of patients with this disease. Recent advances in cancer genomics have revealed the genetic landscape of pancreatic cancer, and clinical trials are currently being conducted to match the treatment to underlying mutations. Liquid biopsy-based diagnosis is a promising method to start personalized treatment. In addition to genome-based medicine, personalized models have been studied as a tool to test candidate drugs to select the most efficacious treatment. The innovative three-dimensional organoid culture platform, as well as patient-derived xenografts can be used to conduct genomic and functional studies to enable personalized treatment approaches. Combining genome-based medicine with drug screening based on personalized models may fulfill the promise of precision medicine for pancreatic cancer.

Pancreatic adenocarcinoma: molecular drivers and the role of targeted therapy

Prognosis from pancreatic ductal adenocarcinoma (PDAC) continues to be poor despite the many efforts channeled to improve its management. Although the mainstay treatment is still traditional chemotherapy, recent advances highlighted a promising potential for targeted therapy in the management of this disease. Those advances emphasize the significance of timely genomic profiling of tumor tissue as well as germline testing of patients to identify potential markers of targeted therapy. While targeted therapy is reserved for a relatively small subset of patients with PDAC, ongoing research is uncovering additional markers, and targeted agents, that will hopefully translate to better outcomes for patients.

Duration of therapy for locally advanced pancreatic cancer: Does it matter?

INTRODUCTION

Evidence-based recommendations on duration of multiagent systemic therapy for LAPC are lacking. Herein, we assess the impact of duration of combination systemic therapy on survival of patients with LAPC.

METHODS

The National Cancer Database was interrogated to identify patients with untreated LAPC diagnosed from 2004 to 2014. Patients treated with ≥ 1 month of multiagent chemotherapy (MAC) and ≥ 6 months of follow-up were included. Kaplan-Meier survival curves were generated to examine OS of each MAC duration group. Univariable and multivariable Cox proportional hazards regression was used to examine the association between OS with demographic and clinical variables. Statistical computations were performed using SAS Software Version 9.4.

RESULTS

Of the 3410 patients, 1114 met inclusion criteria. Median age was 64 years. Median treatment duration was 3.2 months (range 1-19.8). Median follow-up was 23.5 months (range 3-120). Median OS of all patients was 9.4 months (95% CI: 8.7-10.1). Median OS of patients receiving ≥ 1-4 months, >4-6 months and > 6 months of MAC was 8.4 months (95% CI: 7.7-9), 10.2 months (95% CI: 9-11.8), and 12.8 months (95% CI 11.6-16). Twelve-month survival was 37% for patients receiving ≥ 1-4 months, 43% for > 4-6 months, and 56% for > 6 months. Female sex (P = .02), higher median household income (P = .03), and longer duration of MAC (P < .001) were independently associated with improved OS following multivariable analysis.

CONCLUSION

This analysis in LAPC patients suggests that combination systemic therapy regimens of 6 months or more may optimize survival outcomes. Further investigation on the duration of systemic therapy question in LAPC is needed.

New Treatment Strategies for Metastatic Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is typically diagnosed at an advanced stage, with systemic therapy being the mainstay of treatment. Survival continues to be limited, typically less than 1 year. The PDAC microenvironment is characterized by a paucity of malignant epithelial cells, abundant stroma with predominantly immunosuppressive T cells and myelosuppressive-type macrophages (M2), and hypovascularity. The current treatment options for metastatic PDAC are modified (m)FOLFIRINOX /FOLFIRINOX or nab-paclitaxel and gemcitabine in patients with good performance status (PS) (ECOG 0-1/KPS 70-100%) and gemcitabine with or without a second agent for those with ECOG PS 2-3. New therapies are emerging, and the current guidelines endorse both germline and somatic testing in PDAC to evaluate actionable findings. Important themes related to new therapeutic approaches include DNA damage repair strategies, immunotherapy, targeting the stroma, and cancer-cell metabolism. Targeted therapy alone (outside small genomically defined subsets) or in combination with standard cytotoxic therapy, thus far, has proven disappointing in PDAC; however, novel therapies are evolving with increased integration of genomic profiling along with a better understanding of the tumor microenvironment and immunology. A small but important sub-group of patients have some of these agents available in the clinics for use. Olaparib was recently approved by the US Food and Drug Administration for maintenance therapy in germline BRCA1/2 mutated PDAC following demonstration of survival benefit in a phase 3 trial. Pembrolizumab is approved for patients with defects in mismatch repair/microsatellite instability. PDAC with wild-type KRAS represents a unique subgroup who have enrichment of potentially targetable oncogenic drivers. Small-molecule inhibitors including ERBB inhibitors (e.g., afatinib, MCLA-128), TRK inhibitors (e.g., larotrectinib, entrectinib), ALK/ROS inhibitor (e.g., crizotinib), and BRAF/MEK inhibitors are in development. In a small subset of patients with the KRASG12C mutation, a KRASG12C inhibitor, AMG510, and other agents are being investigated. Major efforts are underway to effectively target the tumor microenvironment and to integrate immunotherapy into the treatment of PDAC, and although thus far the impact has been modest to ineffective, nonetheless, there is optimism that some of the challenges will be overcome.