Roles of microbiota in pancreatic cancer development and treatment.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with poor prognosis. This is due to the fact that most cases are only diagnosed at an advanced and palliative disease stage, and there is a high incidence of therapy resistance. Despite ongoing efforts, to date, the mechanisms underlying PDAC oncogenesis and its poor responses to treatment are still largely unclear. As the study of the microbiome in cancer progresses, growing evidence suggests that bacteria or fungi might be key players both in PDAC oncogenesis as well as in its resistance to chemo- and immunotherapy, for instance through modulation of the tumor microenvironment and reshaping of the host immune response. Here, we review how the microbiota exerts these effects directly or indirectly via microbial-derived metabolites. Finally, we further discuss the potential of modulating the microbiota composition as a therapy in PDAC.

Tumor Response Evaluation Using iRECIST: Feasibility and Reliability of Manual Versus Software-Assisted Assessments.

OBJECTIVES: To compare the feasibility and reliability of manual versus software-assisted assessments of computed tomography scans according to iRECIST in patients undergoing immune-based cancer treatment. METHODS: Computed tomography scans of 30 tumor patients undergoing cancer treatment were evaluated by four independent radiologists at baseline (BL) and two follow-ups (FU), resulting in a total of 360 tumor assessments (120 each at BL/FU1/FU2). After image interpretation, tumor burden and response status were either calculated manually or semi-automatically as defined by software, respectively. The reading time, calculated sum of longest diameter (SLD), and tumor response (e.g., "iStable Disease") were determined for each assessment. After complete data collection, a consensus reading among the four readers was performed to establish a reference standard for the correct response assignments. The reading times, error rates, and inter-reader agreement on SLDs were statistically compared between the manual versus software-assisted approaches. RESULTS: The reading time was significantly longer for the manual versus software-assisted assessments at both follow-ups (median [interquartile range] FU1: 4.00 min [2.17 min] vs. 2.50 min [1.00 min]; FU2: 3.75 min [1.88 min] vs. 2.00 min [1.50 min]; both p < 0.001). Regarding reliability, 2.5% of all the response assessments were incorrect at FU1 (3.3% manual; 0% software-assisted), which increased to 5.8% at FU2 (10% manual; 1.7% software-assisted), demonstrating higher error rates for manual readings. Quantitative SLD inter-reader agreement was inferior for the manual compared to the software-assisted assessments at both FUs (FU1: ICC = 0.91 vs. 0.93; FU2: ICC = 0.75 vs. 0.86). CONCLUSIONS: Software-assisted assessments may facilitate the iRECIST response evaluation of cancer patients in clinical routine by decreasing the reading time and reducing response misclassifications.

Trifluridine/Tipiracil Based Chemoradiation in locally Advanced Rectal Cancer: The Phase I/II TARC Trial.

BACKGROUND: Optimizing functional outcomes and securing long-term remissions are key goals in managing patients with locally advanced rectal cancer. In this proof-of-concept study, we set out to further optimize neoadjuvant therapy by integrating the radiosensitizer trifluridine/tipiracil and explore the potential of cell free tumor DNA (ctDNA) to monitor residual disease. METHODS: About 10 patients were enrolled in the phase I dose finding part which followed a 3 + 3 dose escalation design. Tipiracil/trifluridine was administered concomitantly to radiotherapy. ctDNA monitoring was performed before and after chemoradiation with patient-individualized digital droplet PCRs. RESULTS: No dose-limiting toxicities were observed at the maximum tolerated dose level of 2 × 35 mg/m² trifluridine/tipiracil. There were 9 grade 3 adverse events, of which 8 were hematologic with anemia and leukopenia. Chemoradiation yielded a pathological complete response in 1 out of 8 assessable patients, downstaging in nearly all patients, and 1 clinical complete response referred for watchful waiting. Three of 4 assessable patients with residual tumor cells at pathological assessment remained liquid biopsy positive after chemoradiation, but 1 turned negative. CONCLUSION: In this exploratory phase I trial, the novel combination of neoadjuvant trifluridine/tipiracil and radiotherapy proved to be feasible, tolerable, and effective. However, the application of liquid biopsy as a potential marker for therapeutic de-escalation in the neoadjuvant setting requires additional research and prospective validation. The trial was registered at ClinicalTrials.gov: NCT04177602.