Biological Hallmarks and New Therapeutic Approaches for the Treatment of PDAC

Targeting Neoantigens in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer and is currently the third leading cause of cancer-related death in the United States after lung and colon cancer. PDAC is estimated to be the second leading cause of cancer-related death by 2030. The diagnosis at a late stage is the underlying cause for higher mortality and poor prognosis after surgery. Treatment resistance to chemotherapy and immunotherapy results in recurrence after surgery and poor prognosis. Neoantigen burden and CD8+ T-cell infiltration are associated with clinical outcomes in PDAC and paucity of neoantigen-reactive tumor-infiltrating lymphocytes may be the underlying cause for treatment resistance for immunotherapy. This suggests a need to identify additional neoantigens and therapies targeting these neoantigens to improve clinical outcomes in PDAC. In this review, we focus on describing the pathophysiology, current treatment strategies, and treatment resistance in PDAC followed by the need to target neoantigens in PDAC.

Circular RNA circTMEM59 inhibits progression of pancreatic ductal adenocarcinoma by targeting miR-147b/SOCS1: An in vitro study

Purpose

This study aimed to detect the role and mechanism of circTMEM59 in pancreatic ductal adenocarcinoma (PDAC).

Methods

66 paired PDAC tissues and normal samples were harvested from patients diagnosed and undergoing pancreatic cancer surgery in our hospital. The expression of circTMEM59 in PDAC tissues and cell lines was detected. Based on bioinformatics information, the circTMEM59 mimics, miR-147b mimics, miR-147b inhibitor and si-suppressor of cytokine signaling 1 (SOCS1) were transfected into PDAC cells. The expression levels of circTMEM59, miR-147b and SOCS1 were detected by quantitative real-time polymerase chain reaction (qRT-PCR). RNA interaction was confirmed by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Cell invasion and proliferation were evaluated by Transwell and Cell Counting Kit-8 (CCK-8) assays. The protein expression was detected by Western blot.

Results

CircTMEM59 was confirmed to be downregulated in PDAC tumor tissues and cells. Low expression of circTMEM59 was closely correlated with the short survival time and poor clinicopathological characteristics. By up-regulating the expression of circTMEM59 in PDAC cells, cell proliferation, invasion and epithelial-mesenchymal transition (EMT) were inhibited. More importantly, miR-147b could be sponged by circTMEM59, and knockdown of miR-147b inhibited progression of PDAC cells. Further study revealed that SOCS1 was targeted by miR-147b. SOCS1 expression was negatively related to miR-147b expression and positively related to circTMEM59 expression in PDAC tissues. Upregulated miR-147b and downregulated SOCS1 could rescue the effects of circTMEM59 on cell proliferation, EMT and invasion.

Conclusion

Our data indicated that circTMEM59 inhibited cell proliferation, invasion and EMT of PDAC by regulating miR-147b/SOCS1 axis.

A Simple Overview of Pancreatic Cancer Treatment for Clinical Oncologists

Pancreatic cancer (PDAC) is one of the most aggressive solid tumors and is showing increasing incidence. The aim of our review is to provide practical help for all clinical oncologists and to summarize the current management of PDAC using a simple "ABC method" (A-anatomical resectability, B-biological resectability and C-clinical conditions). For anatomically resectable PDAC without any high-risk factors (biological or conditional), the actual standard of care is represented by surgery followed by adjuvant chemotherapy. The remaining PDAC patients should all be treated with initial systemic therapy, though the intent for each is different: for borderline resectable patients, the intent is neoadjuvant; for locally advanced patients, the intent is conversion; and for metastatic PDAC patients, the intent remains just palliative. The actual standard of care in first-line therapy is represented by two regimens: FOLFIRINOX and gemcitabine/nab-paclitaxel. Recently, NALIRIFOX showed positive results over gemcitabine/nab-paclitaxel. There are limited data for maintenance therapy after first-line treatment, though 5-FU or FOLFIRI after initial FOLFIRINOX, and gemcitabine, after initial gemcitabine/nab-paclitaxel, might be considered. We also dedicate space to special rare conditions, such as PDAC with germline BRCA mutations, pancreatic acinar cell carcinoma and adenosquamous carcinoma of the pancreas, with few clinically relevant remarks.

CDKs Functional Analysis in Low Proliferating Early-Stage Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly devastating disease with a poor prognosis and growing incidence. In this study, we explored the potential roles of CDK1, CDK2, CDK4, and CDK6 in the progression of early-stage PDAC. Clinicopathologic and mRNA expression data and treatment information of 140 patients identified with stage I/II PDAC who underwent pancreaticoduodenectomy were obtained from the Cancer Genome Atlas data set. Our bioinformatic analysis showed that higher CDK1, CDK2, CDK4, or CDK6 expression was associated with a shorter median survival of the early-stage PDAC patients. Of note, in the low-proliferating pancreatic cancer group, CDKs expressions were significantly associated with proteins functioning in apoptosis, metastasis, immunity, or stemness. Among the low-proliferating PDAC, higher expression of CDK1 was associated with the shorter survival of patients, suggesting that CDK1 may regulate PDAC progression through cell cycle-independent mechanisms. Our experimental data showed that CDK1 knockdown/inhibition significantly suppressed the expression levels of AHR and POU5F1, two critical proteins functioning in cancer cell metastasis and stemness, in low-proliferating, but not in high-proliferating pancreatic cancer cells. In all, our study suggests that CDKs regulate PDAC progression not only through cell proliferation but also through apoptosis, metastasis, immunity, and stemness.

Assessment of stromal SCD-induced drug resistance of PDAC using 3D-printed zPDX model chips

Lipid metabolism is extensively reprogrammed in pancreatic ductal adenocarcinoma (PDAC). Stearoyl-coenzyme A desaturase (SCD) is a critical lipid regulator that was unexplored in PDAC. Here, we characterized the existence of cancer-associated fibroblasts (CAFs) with high SCD expression, and revealed them as an unfavorable prognostic factor. Therefore, primary CAFs and pancreatic cancer cells were harvested and genetically labeled. The mixture of CAFs and cancer cells were co-injected into scd^-/-; prkdc^-/-, or hIGF1/INS-expressing zebrafish to generate patient-derived xenograft models (zPDX). The models were aligned in 3D-printed chips for semi-automatic drug administration and high-throughput scanning. The results showed that chaperoning of the SCD-high CAFs significantly improved the drug resistance of pancreatic cancer cells against gemcitabine and cisplatin, while the administration of SCD inhibitors neutralized the protective effect. Our studies revealed the prognostic and therapeutic value of stromal SCD in PDAC, and proposed the application of zPDX model chips for drug testing.

It Takes Two to Tango: Potential Prognostic Impact of Circulating TGF-Beta and PD-L1 in Pancreatic Cancer

Background: Pancreatic ductal adenocarcinoma (PDAC) is a highly devastating disease with rising incidence and poor prognosis. The lack of reliable prognostic biomarkers hampers the individual evaluation of the survival and recurrence potential. Methods: Here, we investigate the value of plasma levels of two potential key players in molecular mechanisms underlying PDAC aggressiveness and immune evasion, soluble TGF-beta (sTGF-beta) and sPD-L1, in both metastatic and radically-resected PDAC. To this aim we prospectively enrolled 38 PDAC patients and performed appropriate statistical analyses in order to evaluate their correlation, and role in the prediction of disease relapse/progression, and patients’ outcome. Results: Metastatic patients showed lower levels of circulating sTGF-beta and higher levels of sPD-L1 compared to radically-resected patients. Moreover, a decrease in sTGF-beta levels (but not sPD-L1) was significantly associated with disease relapse in radically-resected patients. We also observed lower sTGF-beta at disease progression after first-line chemotherapy in metastatic patients, though this change was not statistically significant. We found a significant correlation between the levels of sTGF-beta and sPD-L1 before first-line chemotherapy. Conclusions: These findings support the possible interaction of TGF-beta and PD-L1 pathways and suggest that sTGF-beta and sPD-L1 might synergize and be new potential blood-based biomarkers.

A Review on the Efficacy and Safety of Nab-Paclitaxel with Gemcitabine in Combination with Other Therapeutic Agents as New Treatment Strategies in Pancreatic Cancer

Pancreatic cancer has one of the highest mortality rates among cancers, and a combination of nab-paclitaxel with gemcitabine remains the cornerstone of first-line therapy. However, major advances are required to achieve improvements in patient outcomes. For this reason, several research groups have proposed supplementing treatment with other therapeutic agents. Ongoing studies are being conducted to find the optimal treatment in a first-line setting. In this work, we used a search strategy to compare studies on the efficacy and safety of nab-paclitaxel with gemcitabine in combination with other therapeutic agents based on the criteria of the Preferred Reporting Items for Systematic Reviews. We found seven studies in different clinical phases that met the inclusion criteria. The seven therapeutic agents were ibrutinib, necuparanib, tarextumab, apatorsen, cisplatin, enzalutamide, and momelotinib. Although these therapeutic agents have different mechanisms of action, and molecular biology studies are still needed, the present review was aimed to answer the following question: which formulations of the nab-paclitaxel/gemcitabine regimen in combination with other therapeutic agents are safest for patients with previously untreated metastatic pancreas ductal adenocarcinoma? The triple regimen is emerging as the first-line option for patients with pancreatic cancer, albeit with some limitations. Thus, further studies of this regimen are recommended.

Should patients on levothyroxine therapy be screened for pancreatic cancer?

BACKGROUND

Pancreatic ductal adenocarcinoma is an aggressive disease with increasing incidence. Thyroid hormones play different roles in development and physiological processes of the entire digestive system, including pancreas. Therefore, many have hypothesized that thyroid hormone supplementation for hypothyroidism disorders might increase the risk of malignancy.

PATIENTS AND METHODS

We conducted retrospective observational mono-centre study. The aim was to examine the prevalence of thyroid disorders among patients with pancreatic cancer. Moreover, we investigated the impact of thyroid hormone supplementation in pancreatic cancer patients' outcome and the correlation with various clinicopathologic parameters.

RESULTS

A total of 92 consecutive pancreatic cancer patients were retrospectively reviewed: 18.5% patients had a history of hypothyroidism and all received a replacement hormone therapy with levothyroxine, in particular 20% in metastatic group and 11% in radically resected PDAC patients' group. Nor in radically resected neither in metastatic group, we did not observe any statistically significant difference in outcome between the group with or without thyroid disorders. On multivariate analyses, cox proportional hazards model analysis showed that only the presence of perineural invasion was associated with a significantly higher hazard ratio for overall survival in metastatic PDAC patients (HR=2.7; 95%CI=1.029-6.925; p=0.009).

CONCLUSIONS

We observed higher prevalence of thyroid disorders in PDAC patients. Further studies are warranted to explore the impact of levothyroxine therapy on outcome in PDAC patients.