Colorectal Cancer Heterogeneity and the Impact on Precision Medicine and Therapy Efficacy

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.

Efficacy and Safety of Systemic Treatments Among Colorectal Cancer Patients: A Network Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Systemic treatments, namely, either monotherapy or combination therapy, are commonly administered to patients with advanced or metastatic colorectal cancer (CRC). This study aimed to provide the complete efficacy and safety profiles and ranking of systemic therapies for the treatment of unresectable advanced or metastatic CRC.

METHODS

We searched PubMed, Embase, the Cochrane Library, and ClinicalTrials.gov from inception until June 30, 2021, and also the bibliographies of relevant studies. Randomized controlled trials comparing two or more treatments, namely, at least capecitabine, 5-fluorouracil, leucovorin, irinotecan, bevacizumab, cetuximab, oxaliplatin, or panitumumab were investigated. A network meta-analysis using the Bayesian approach was performed to compare the efficacy and safety of treatments. The surface under the cumulative ranking curve (SUCRA) was calculated for the probability of each treatment as the most effective. The overall response rate (ORR), disease control rate (DCR), overall survival (OS), progression-free survival (PFS), adverse events (AEs) grade ≥3, and serious adverse events (SAEs) were evaluated.

RESULTS

One hundred two publications with 36,147 participants were assigned to 39 different treatments. Among 11 treatments with full information on six outcomes, FOLFIRI/FOLFOX/FOLFOXIRI + bevacizumab significantly improved both the ORR and DCR, compared to FOLFIRI. Although FOLFOX and FOLFIRI/FOLFOX + cetuximab significantly prolonged both OS and PFS, treatments were comparable in terms of AEs grade ≥3 and SAEs. The top highest SUCRA values were observed in the FOLFOXIRI + panitumumab group for ORR (96%) and DCR (99%), FOLFIRI + bevacizumab + panitumumab group for OS (62%) and PFS (54%), and FOLFOXIRI + bevacizumab group for AEs grade ≥3 (59%) and SAEs (59%) outcomes.

CONCLUSIONS

These findings suggest an available range of systemic treatment therapies with different efficacy and safety profiles with patients. Further investigations of the side effects and mutation status are required to confirm our findings.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier CRD42019127772.

Current therapy of advanced colorectal cancer according to RAS/RAF mutational status

Colorectal cancer is a clinically and molecularly heterogeneous disease. Currently, extended RAS and BRAF mutation testing is obligatory in routine clinical practice before starting any treatment in the metastatic setting. Treatment decision making also includes assessment of the clinical condition of the patient, definition of the treatment goal, and consideration of the primary tumor site. Biological treatment is part of the first-line drug combination unless contraindicated. Mutational status is significantly associated with the outcome of patients and is strongly predictive for anti-EGFR-targeted therapy. The prognosis of RAS mutant CRC is clearly inferior to wild-type cases. RAS remains an elusive target, and specific treatment options are not yet available. Recently, promising results of a direct KRAS G12C inhibitor have been reported; however, further confirmation is needed. The biomarker landscape in mCRC is evolving; new promising markers are awaited with the chance of more precise targeted treatment.

[Personalized systemic treatment of metastatic colorectal cancer]

This article deals with the treatment of metastatic colorectal cancer (stage IV). The treatment goals and approaches are determined by the resectability status of the metastases: resectable liver and lung metastases are primarily resected and perioperative chemotherapy appears to be dispensable. In potentially resectable metastases, a conversion therapy is attempted to enable a potentially curative resection. In the case of nonresectability the treatment goal is palliative. Induction and maintenance therapy as well as drug holidays are suggested in an attempt to achieve extended survival while maintaining the quality of life, beginning with the best possible individual treatment. For some patients with stage IV, molecular targeted therapies are available. The study situation and approval status are dealt with in detail. With improved molecular characterization of tumors the treatment can be further individualized.