PURPOSE: To investigate whether intermittent treatment after an induction phase of first-line schedule of fluorouracil, leucovorin, and irinotecan (FOLFIRI) plus panitumumab (PAN) prevents or delays the onset of resistance and improves safety and compliance with treatment in patients with unresectable RAS / BRAF wild-type (wt) metastatic colorectal cancer (mCRC). PATIENTS AND METHODS: IMPROVE (ClinicalTrials.gov identifier: NCT04425239 ) was an open-label, multicenter, randomized phase II noncomparative trial. Patients with unresectable RAS / BRAF wt mCRC were randomly assigned (1:1) to receive FOLFIRI plus PAN continuously until progression (arm A) or intermittently, with treatment-free intervals (arm B) until progression on treatment, toxicity, or death. The primary end point was progression-free survival on treatment (PFSot) at 12 months. Assuming a null hypothesis of median PFSot time ≤7 months and target PFSot ≥10 months, 65 patients per arm were needed to achieve 80% power and 10% type I error, according to the binomial test. RESULTS: Between May 2018 and June 2021, 69 patients were randomly assigned to arm A and 68 to arm B. The median number of treatment cycles was 13 in arm A and 16 in arm B. At a median follow-up of 43.2 months (IQR, 35.0-50.5), median PFSot was 11.2 and 17.5 months with 12-month PFSot rates of 45.7% and 58.5%, for arms A and B, respectively. The overall response rates were 68.1% and 61.2%, and median overall survival rates were 36.3 and 35.1 months in arms A and B, respectively. The overall rate of grade >2 skin PAN-related adverse events was 30.3% in arm A and 17.9% in arm B. CONCLUSION: Intermittent FOLFIRI plus PAN after the induction phase was feasible, and the primary end point was met with reduced toxicity while allowing patients more time off treatment.

Novel targeted therapies for metastatic colorectal cancer are needed to personalize treatments by guiding specific biomarkers selected on the genetic profile of patients. RAS and BRAF inhibitors have been developed for patients who become unresponsive to standard therapies. Sotorasib and adagrasib showed promising results in phase I/II basket trial and a phase III trial was planned with a combination of these RAS inhibitors and anti-EGFR monoclonal antibodies. Encorafenib and binimetinib were administered in phase II clinical trials for BRAF mutated patients. Pembrolizumab is now recommended in patients exhibiting microsatellite instability. Larotrectinib and entrectinib showed a fast and durable response with few and reversible adverse events in cases with NTRK fusions. Trastuzumab and trastuzumab deruxtecan exhibited promising and durable activity in HER-2-positive patients. In this review, the reasons for an extension of the molecular profile of patients were assessed and placed in the context of the advancements in the understanding of genetics. We highlight the differential effect of new targeted therapies through an ever-deeper characterization of tumor tissue. An overview of ongoing clinical trials is also provided.

The results of new randomized clinical trials show that immunotherapy is the preferred treatment for a small proportion of metastatic colorectal cancers (mCRCs). For microsatellite instability-high mCRC, pembrolizumab, nivolumab, and ipilimumab are currently authorized as first- and second-line immune checkpoint agents. However, the problem concerns tumors with microsatellite stability where the “cold” microenvironment does not allow immunotherapy to function properly. All efforts are now aimed at ensuring that this microenvironment is inflamed and “hot”. In this review, we examine recent studies on immunotherapy for mCRC and assess novel drivers of immunotherapy response.

Although colorectal cancer is increasingly being diagnosed in older patients, their number is largely underrepresented in phase II or III clinical trials. Consequently, guidelines and the SIOG recommendations are not sufficiently clear regarding the treatment of these patients, particularly when chemotherapy is combined with monoclonal antibodies (bevacizumab, cetuximab, and panitumumab). Targeted therapy based on the use of anti-epidermal growth factor receptors (EGFRs) is conditioned by the potential for increased toxicity, making it more difficult to treat an older, rat sarcoma virus (RAS) and B rapidly accelerated fibrosarcoma (BRAF) wild-type patient. In light of a more detailed characterization of the older population, modernly differentiable between fit, vulnerable, or frail patients on the basis of the comprehensive geriatric assessment, and of the analysis of more recent studies, this review fully collects data from the literature, differentiating the results on functional status patients.

Alfredo Colombo and Concetta Maria Porretto. Int J Gastrointest Interv 2023;12:110-4. https://doi.org/10.18528/ijgii230011