Real-world study on microsatellite instability and mismatch repair deficiency testing patterns among patients with metastatic colorectal cancer in Spain.

PURPOSE: Clinical practice guidelines recommend that all patients with metastatic colorectal cancer (mCRC) should be tested for mismatch repair deficiency (dMMR) or microsatellite instability-high (MSI-H). We aimed to describe the dMMR/MSI-H testing practice in patients with mCRC in Spanish centers. METHODS: Multicenter, observational retrospective study that included patients newly diagnosed with mCRC or who progressed to a metastatic stage from early/localized stages. RESULTS: Three hundred patients were included in the study from May 2020 through May 2021, with a median age of 68 years, and two hundred twenty-five (75%) had stage IV disease at initial diagnosis; two hundred eighty-four patients received first-line treatment, and dMMR/MSI-H testing was performed in two hundred fifty-one (84%) patients. The results of the dMMR/MSI-H tests were available in 61 (24%) of 251 patients before the diagnosis of metastatic disease and in 191 (81%) of 236 evaluable patients for this outcome before the initiation of first-line treatment. Among the 244 patients who were tested for dMMR/MSI-H with IHC or PCR, 14 (6%) were MMR deficient. The most frequent type of first-line treatment was the combination of chemotherapy and biological agent, that was received by 71% and 50% of patients with MMR proficient and deficient tumors, respectively, followed by chemotherapy alone, received in over 20% of patients in each subgroup. Only 29% of dMMR/MSI-H tumors received first-line immunotherapy. CONCLUSION: Our study suggests that a high proportion of patients with mCRC are currently tested for dMMR/MSI-H in tertiary hospitals across Spain. However, there is still room for improvement until universal testing is achieved. TRIAL REGISTRATION: Not applicable.

FOLFOXIRI plus bevacizumab versus FOLFOX plus bevacizumab for patients with metastatic colorectal cancer and ≥3 circulating tumour cells: the randomised phase III VISNÚ-1 trial.

PURPOSE: 5-Fluorouracil/leucovorin, oxaliplatin, irinotecan (FOLFOXIRI) plus bevacizumab is more effective than doublets plus bevacizumab as first-line therapy for metastatic colorectal cancer, but is not widely used because of concerns about toxicity and lack of predictive biomarkers. This study was designed to explore the role of circulating tumour cell (CTC) count as a biomarker to select patients for therapy with FOLFOXIRI-bevacizumab. PATIENTS AND METHODS: VISNÚ-1 was a multicentre, open-label, randomised, phase III study in patients with previously untreated, unresectable, metastatic colorectal carcinoma and ≥3 CTC/7.5 mL blood. Patients received bevacizumab 5 mg/kg plus FOLFOXIRI (irinotecan 165 mg/m2, oxaliplatin 85 mg/m2, leucovorin 400 mg/m2 and 5-fluorouracil 3200 mg/m2) or FOLFOX (oxaliplatin 85 mg/m2, leucovorin 400 mg/m2, 5-fluorouracil 400 mg/m2 then 2400 mg/m2) by intravenous administration every 2 weeks. The primary outcome was progression-free survival (PFS). RESULTS: The intention-to-treat population comprised 349 patients (FOLFOXIRI-bevacizumab, n=172; FOLFOX-bevacizumab, n=177). Median PFS was 12.4 months (95% CI 11.2 to 14.0) with FOLFOXIRI bevacizumab and 9.3 months (95% CI 8.5 to 10.7) with FOLFOX-bevacizumab (stratified HR, 0.64; 95% CI 0.49 to 0.82; p=0.0006). Grade≥3 adverse events were more common with FOLFOXIRI-bevacizumab 85.3% vs 75.1% with FOLFOX-bevacizumab (p=0.0178). Treatment-related deaths occurred in 8 (4.7%) and 6 (3.4%) patients, respectively. CONCLUSIONS: First-line FOLFOXIRI-bevacizumab significantly improved PFS compared with FOLFOX-bevacizumab in patients with metastatic colorectal cancer and ≥3 CTCs at baseline, which indicate a poor prognosis. CTC count may be a useful non-invasive biomarker to assist with the selection of patients for intensive first-line therapy.

Immune microenvironment in colorectal cancer: a new hallmark to change old paradigms.

Impact of immune microenvironment in prognosis of solid tumors has been extensively studied in the last few years. Specifically in colorectal carcinoma, increased knowledge of the immune events around these tumors and their relation with clinical outcomes have led to consider immune microenvironment as one of the most important prognostic factors in this disease. In this review we will summarize and update the current knowledge with respect to this intriguing and complex new hallmark of cancer, paying special attention to infiltration by T-infiltrating lymphocytes and their subtypes in colorectal cancer, as well as its eventual clinical translation in terms of long-term prognosis. Finally, we suggest some possible investigational approaches based on combinatorial strategies to trigger and boost immune reaction against tumor cells.