Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with a notably poor prognosis, in urgent need of improved treatment strategies. The desmoplastic PDAC tumor microenvironment (TME), marked by a high concentration of cancer-associated-fibroblasts (CAFs), is a dynamic part of PDAC pathophysiology which occasions a variety of effects throughout the course of pancreatic tumorigenesis and disease evolution. A better understanding of the desmoplastic TME and CAF biology in particular, should provide new opportunities for improving therapeutics. That CAFs have a tumor-supportive role in oncogenesis is well known, yet research evidence has shown that CAFs also have tumor-repressive functions. In this review, we seek to clarify the intriguing heterogeneity and plasticity of CAFs and their ambivalent role in PDAC tumorigenesis and progression. Additionally, we provide recommendations to advance the implementation of CAF-directed PDAC care. An improved understanding of CAFs' origins, spatial location, functional diversity, and marker determination, as well as CAF behavior during the course of PDAC progression and metastasis will provide essential knowledge for the future improvement of therapeutic strategies for patients suffering from PDAC.

Novel blood-based protein biomarkers may be of value for efficient, accurate, and non-invasive diagnosis of pancreatic cancer. This study assesses the diagnostic accuracy of newly recognized blood-based protein biomarkers for detecting pancreatic cancer, and investigates their added value to CA19-9, the common blood-based biomarker in clinical use for pancreatic cancer. PubMed, Embase, Web of Science, and the Wiley/Cochrane Library were systematically searched from inception until June 2022. A meta-analysis of aggregate and individual participant data was conducted using frequentist and Bayesian hierarchical random-effects models. The added clinical utility of protein biomarkers was investigated using bootstrap bias-corrected decision curve analyses. Aggregate data from 28 primary studies (6127 participants) were included, of which 8 studies (1790 participants) provided individual participant data. CA19-9 was significantly more accurate than MIC-1 for distinguishing pancreatic cancer from benign disease (AUC, 0.83 vs 0.74; relative diagnostic odds ratio [rDOR], 2.10 [95% CI, 0.98–4.48]; p = 0.002), THBS2 (AUC, 0.87 vs 0.69; rDOR, 4.53 [2.16–9.39]; p < 0.0001), TIMP-1 (AUC, 0.91 vs 0.70; rDOR, 8.00 [3.81–16.9]; p < 0.0001), OPN (AUC, 0.89 vs 0.74; rDOR, 4.22 [1.13–15.6]; p < 0.0001), ICAM-1 (AUC, 0.91 vs 0.68; rDOR 9.30 [0.87–99.5]; p < 0.0001), and IGFBP2 (AUC, 0.91 vs 0.68; rDOR, 4.48 [0.78–24.3]; p < 0.0001). The addition of these novel protein biomarkers to CA19-9 did not significantly improve the AUC, and resulted in minor increases or limited decreases in clinical utility. Novel protein biomarkers have moderate diagnostic accuracy, do not outperform CA19-9 in differentiating pancreatic cancer from benign disease, and show limited added clinical value to CA19-9. We propose recommendations to aid the development of minimally invasive diagnostic tests with sufficient clinical utility to improve the management of patients with suspected pancreatic cancer. Bennink Foundation, Dutch Cancer Foundation (KWF Kankerbestrijding), and AIRC.

Distinction of pancreatic ductal adenocarcinoma (PDAC) in the head of the pancreas, distal cholangiocarcinoma (dCCA), and benign periampullary conditions, is complex as they often share similar clinical symptoms. However, these diseases require specific management strategies, urging improvement of non-invasive tools for accurate diagnosis. Recent evidence has shown that the ratio between CA19-9 and bilirubin levels supports diagnostic distinction of benign or malignant hepatopancreaticobiliary diseases. Here, we investigate the diagnostic value of this ratio in PDAC, dCCA and benign diseases of the periampullary region in a novel fashion. To address this aim, we enrolled 265 patients with hepatopancreaticobiliary diseases and constructed four logistic regression models on a subset of patients (n = 232) based on CA19-9, bilirubin and the ratio of both values: CA19-9/(bilirubin⁻¹). Non-linearity was investigated using restricted cubic splines and a final model, the ‘Model Ratio’, based on these three variables was fitted using multivariable fractional polynomials. The performance of this model was consistently superior in terms of discrimination and calibration compared to models based on CA19-9 combined with bilirubin and CA19-9 or bilirubin alone. The ‘Model Ratio’ accurately distinguished between malignant and benign disease (AUC [95% CI], 0.91 [0.86–0.95]), PDAC and benign disease (AUC 0.91 [0.87–0.96]) and PDAC and dCCA (AUC 0.83 [0.74–0.92]) which was confirmed by internal validation using 1000 bootstrap replicates. These findings provide a foundation to improve minimally-invasive diagnostic procedures, ultimately ameliorating effective therapy for PDAC and dCCA.

Most patients with advanced colorectal cancer (CRC) eventually develop resistance to systemic combination therapy. miR-195-5p and miR-497-5p are downregulated in CRC tissues and associated with drug resistance. Sensitization to 5-FU, oxaliplatin, and irinotecan by transfection with miR-195-5p and miR-497-5p mimics was studied using cell viability and clonogenic assays in cell lines HCT116, RKO, DLD-1, and SW480. In addition, proteomic analysis of transfected cells was implemented to identify potential targets. Significantly altered proteins were subjected to STRING (protein-protein interaction networks) database analysis to study the potential mechanisms of drug resistance. Cell viability analysis of transfected cells revealed increased sensitivity to oxaliplatin in microsatellite instable (MSI)/P53 wild-type HCT116 and RKO cells. HCT116 transfected cells formed significantly fewer colonies when treated with oxaliplatin. In sensitized cells, proteomic analysis showed 158 and 202 proteins with significantly altered expression after transfection with miR-195-5p and miR-497-5p mimics respectively, of which CHUK and LUZP1 proved to be coinciding downregulated proteins. Resistance mechanisms of these proteins may be associated with nuclear factor kappa-B signaling and G1 cell-cycle arrest. In conclusion, miR-195-5p and miR-497-5p replacement enhanced sensitivity to oxaliplatin in treatment naïve MSI/P53 wild-type CRC cells. Proteomic analysis revealed potential miRNA targets associated with the cell-cycle which possibly bare a relation with chemotherapy sensitivity.

The clinical management of pancreatic ductal adenocarcinoma (PDAC) is limited by the lack of biomarkers that indicate which treatment will benefit an individual patient. The study of Perera and colleagues identified human equilibrative nucleoside transporter-1 (hENT1) mRNA expression as a predictive biomarker in patients suffering from advanced PDAC (1). Remarkably, hENT1high expression was predictive of response to gemcitabine/nab-paclitaxel. hENT1 levels were not predictive in patients treated with (modified) FOLFIRINOX, which currently is the preferred regimen for advanced PDAC. These results can hopefully pave the way for personalized treatment strategies. However, some key points of the study should be further discussed.Expression of hENT1 was evaluated by RNA sequencing after laser-capture microdissection (LCM) of tumor tissue. These techniques require thorough laboratory expertise and are not easy to implement in the clinic. To promote clinical implementation and overcome the lack of robust antibodies for hENT1 protein detection, the proposed validation study in the PASS-01 trial should compare these techniques with multimodal IHC and PCR techniques (2), and possibly mass spectrometry–based proteomics to examine expression and posttranscriptional modificationsRNA sequencing provides expression levels for all genes, thus revealing many potential targets and underlying pathways. However, the authors only evaluated hENT1 levels, not utilizing the full extent of the valuable data. Conversely, LCM relies on removing stromal microenvironment, which plays an integral role in chemoresistance and is correlated to disease progression (3). Thus, it would be of value to explore the expression of compartment-specific predictive markers in LCM-stroma samples. In addition, samples were taken from primary and metastatic tumors (in a cohort including locally advanced and metastatic patients). The next step for implementation would be to evaluate these findings in biopsies from a neoadjuvant-treated cohort and correlate to clinicopathologic response.In a group of matched progression biopsies, hENT1 expression changed during treatment. This is another important finding, suggesting that hENT1 levels should be monitored during treatment. In addition, the change from hENT1low to hENT1high in FOLFIRINOX-treated patients is in agreement with preclinical studies showing increased hENT1 expression, associated with depletion of intracellular nucleotide pools after exposure to the thymidylate synthase (TS) inhibitor 5-fluoruracil (4). Further studies could evaluate whether modulation of hENT1 by pretreatment with FOLFIRINOX or TS-inhibitors may improve the therapeutic benefit of gemcitabine/nab-paclitaxel.To conclude, we congratulate the authors on their thorough research on the predictive role of hENT1 for PDAC, and believe that these results lay the groundworks for future research aimed to understand the link between hENT1 and patient outcomes.See the Response, p. 2945H.W. van Laarhoven reports personal fees from AstraZeneca, Daiichy, Dragonfly, MSD, Astellas, Lilly; grants and personal fees from BMS, Servier; grants from Incyte, Merck, Roche; and personal fees from Novartis outside the submitted work; in addition, H.W. van Laarhoven has a patent for US20210145964A1 pending to Bijlsma/van Laarhoven. No disclosures were reported by the other authors.This article was funded by the Dutch Cancer Society (to G. Kazemier and E. Giovannetti), Bennink Foundation (the Netherlands; to G. Kazemier, L.N.C. Boyd, M. Ali, J.R. Puik, and E. Giovannetti) and Italian Association for Cancer Research (Italy; to E. Giovannetti).

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most aggressive tumours, with a 5-year survival rate of approximately 8 per cent¹. This is mostly due to the delay in early diagnosis and to tumour resistance against treatments, despite considerable recent effort in both preclinical and clinical research^2–5. New studies are needed to identify potential risk factors of progression and incidence of PDAC.