Progression-free survival remains poor over sequential lines of systemic therapy in patients with BRAF-mutated colorectal cancer

Antitumor effects of immunotherapy combined with BRAF and MEK inhibitors in BRAF V600E metastatic colorectal cancer

BRAF-mutated colorectal cancer correlates with poor prognosis and limited response to standard treatments. Combining immune checkpoint inhibitors with BRAF/MEK inhibitors shows promise against BRAF-mutant melanoma in both preclinical and clinical trials. Therefore, we hypothesized that the treatment would be effective against BRAF-mutant colorectal cancer. In this study, we assessed the efficacy of combining immune checkpoint inhibitors with BRAF and/or MEK inhibitors in BRAF-mutant colorectal cancers. We treated BRAF V600E colorectal cancer cells HT-29 and SNU-1235 with encorafenib (BRAF inhibitor) and binimetinib (MEK inhibitor) and assessed the degrees of MAPK inhibition, JAK/STAT inhibition, cell viability, apoptosis, and the expression of antigen presenting machinery. We also inoculated HT-29 cells into mice and treated them with an immune checkpoint inhibitor (durvalumab), encorafenib, and binimetinib for 4 weeks. We found that treatment with BRAF inhibitor, MEK inhibitor, or their combination led to significant tumor growth reduction, along with the MAPK and JAK/STAT pathway inhibition, antigen presenting machinery induction, and cytotoxic T cell activation. Our study demonstrates the potential effectiveness of combining immune checkpoint inhibitors with BRAF or MEK inhibitors for BRAF-mutated colorectal cancers.

Expert consensus on the optimal management of BRAFV600E-mutant metastatic colorectal cancer in the Asia-Pacific region

The burden of colorectal cancer (CRC) is high in the Asia-Pacific region, and several countries in this region have among the highest and/or fastest growing rates of CRC in the world. A significant proportion of patients will present with or develop metastatic CRC (mCRC), and BRAFV600E-mutant mCRC represents a particularly aggressive phenotype that is less responsive to standard chemotherapies. In light of recent therapeutic advances, an Asia-Pacific expert consensus panel was convened to develop evidence-based recommendations for the diagnosis, treatment, and management of patients with BRAFV600E-mutant mCRC. The expert panel comprised nine medical oncologists from Australia, Hong Kong, Singapore, and Taiwan (the authors), who met to review current literature and develop eight consensus statements that describe the optimal management of BRAFV600E-mutant mCRC in the Asia-Pacific region. As agreed by the expert panel, the consensus statements recommend molecular testing at diagnosis to guide individualized treatment decisions, propose optimal treatment pathways according to microsatellite stability status, advocate for more frequent monitoring of BRAFV600E-mutant mCRC, and discuss local treatment strategies for oligometastatic disease. Together, these expert consensus statements are intended to optimize treatment and improve outcomes for patients with BRAFV600E-mutant mCRC in the Asia-Pacific region.

An immunohistochemical and molecular genetic study of 60 colorectal carcinoma brain metastases in pursuit of predictive biomarkers for cancer therapy

Colorectal carcinoma brain metastases (n = 60) were studied using next-generation sequencing and immunohistochemistry. RAS and BRAF mutations were detected in 58.2% and 7.3% of cases, respectively. Patients with RAS- and BRAF-mutant tumors could potentially benefit from the treatment with inhibitors. TP53 mutations were detected in 69.1% of metastases. Moreover, altered p53 expression was seen in 91.2% of cases. APC mutations were present in 41.8% of tumors. Diffuse nuclear accumulation of β-catenin was seen in 10.2% of metastases, although only 1 CTNNB1 mutant was identified. Nevertheless, targeting p53 and Wnt/β-catenin pathways may have potential therapeutic implications. Casein kinase 1α1 expression indicating susceptibility to protein kinase inhibitors, was seen in 95% metastases including 10 with strong immunoreactivity. The immune checkpoint marker CD276, a promising target for immunotherapy, was present on tumor cells in 50.8% of metastases and on stromal cells in almost all cases. PRAME, another immunotherapy target, was expressed in 21.7% of tumors. HER2 membrane immunostaining detected in 13.3% of cases implicated potential treatment with HER2 inhibitors. Expression of SLFN11, a predictor of response to DNA-damaging chemotherapies, and a biomarker of sensitivity to PARP inhibitors was seen in 8.3% of tumors. In 6.7% of metastases loss or partial loss of MTAP expression suggested sensitivity to PRMT5 inhibitors. CD44v5 expressed in 35% of cases indicated potential therapeutic utility of anti-CD44v5 monoclonal antibody treatment. Identification of predictive biomarkers through genomic profiling and proteomic analyses is a crucial step toward individually tailored therapeutic regimens for patients with colorectal carcinoma brain metastases.

Second-line systemic treatment for metastatic colorectal cancer: A systematic review and Bayesian network meta-analysis based on RCT

BACKGROUND

The optimal second-line systemic treatment for metastatic colorectal cancer (mCRC) is inconclusive.

METHODS

We searched PubMed, Web of Science, EMBASE, and Cochrane Library for RCTs comparing second-line systemic treatments for mCRC from the inception of each database up to February 3, 2024. Markov Chain Monte Carlo (MCMC) technique was used in this network meta-analysis (NMA) to generate the direct and indirect comparison results among multiple treatments in progression-free survival (PFS), overall response rate (ORR), overall survival (OS), complete response (CR), partial response (PR), grade 3 and above adverse events (Grade ≥ 3AE), and any adverse events (Any AE). The surface under the cumulative ranking curve (SUCRA) was adopted to evaluate the probability of each treatment being the optimum intervention. Subgroup analyses were performed based on the RAS gene status.

RESULTS

A total of 47 randomized controlled trials were included, involving 16,925 patients and 44 second-line systemic treatments. In improving OS, FOLFOX + Bevacizumab + Erlotinib exhibited significant superiority (SUCRA:92.7%). In improving PFS, Irinotecan + CMAB009 (SUCRA:86.4%) had advantages over other treatments. FOLFIRI + Trebananib (SUCRA:88.1%) had a significant advantage in improving ORR. Among multiple second-line treatments, the SUCRA values of FOLFOX + Bevacizumab in PFS, OS, ORR, and PR were 83.4%, 74.0%, 81.1%, and 86.1%, respectively, and the safety was not significantly different from other interventions. Subgroup analyses showed that FOLFIRI + Bevacizumab + panitumumab ranked among the top in survival outcomes in the RAS-mutant population (OS SUCRA: 87.9%; PFS SUCRA: 70.2%); whereas in the RAS-wild-type population, FOLFIRI + Bevacizumab significantly improved survival outcomes (OS SUCRA: 73.2%; PFS SUCRA: 65.1%).

CONCLUSION

For most people, FOLFOX + Bevacizumab may be the best second-line systemic treatment regimen for mCRC. For RAS-mutant populations, FOLFIRI + Bevacizumab + Panitumumab is recommended. However, the therapeutic effect may be affected by the patient's physiological state, and clinicians should apply it based on actual conditions.

Multigene Panel Next-Generation Sequencing Techniques in the Management of Patients with Metastatic Colorectal Carcinoma: The Way Forward for Personalized Treatment? A Single-Center Experience

The efficacy and cost-effectiveness of Multigene Panel Next-Generation Sequencing (NGS) in directing patients towards genomically matched therapies remain uncertain. This study investigated metastatic colorectal cancer (mCRC) patients who underwent NGS analysis on formalin-fixed paraffin-embedded tumor samples. Data from 179 patients were analyzed, revealing no mutations in 39 patients (21.8%), one mutation in 83 patients (46.4%), and two or more mutations in 57 patients (31.8%). KRAS mutations were found in 87 patients (48.6%), including KRAS G12C mutations in 5 patients (2.8%), PIK3CA mutations in 40 patients (22.4%), and BRAF mutations in 26 patients (14.5%). Less common mutations were identified: ERBB2 in five patients (2.8%) and SMO in four patients (2.2%). Additionally, MAP2K1, CTNNB1, and MYC were mutated in three patients (2.4%). Two mutations (1.1%) were observed in ERBB3, RAF1, MTOR, JAK1, and FGFR2. No significant survival differences were observed based on number of mutations. In total, 40% of patients had druggable molecular alterations, but only 1.1% received genomically guided treatment, suggesting limited application in standard practice. Despite this, expanded gene panel testing can identify actionable mutations, aiding personalized treatment strategies in metastatic CRC, although current eligibility for biomarker-guided trials remains limited.

BRAFV600E-Mutant Metastatic Colorectal Cancer: Current Evidence, Future Directions, and Research Priorities

BRAFV600E-mutant metastatic colorectal cancer represents a distinct molecular phenotype known for its aggressive biological behavior, resistance to standard therapies, and poor survival rates. Improved understanding of the biology of the BRAF oncogene has led to the development of targeted therapies that have paved the way for a paradigm shift in managing this disease. However, despite significant recent advancements, responses to targeted therapies are short-lived, and several challenges remain. In this review, we discuss how progress in treating BRAFV600E-mutant metastatic colorectal cancer has been made through a better understanding of its unique biological and clinical features. We provide an overview of the evidence to support current treatment approaches and discuss critical areas of need and future research strategies that hold the potential to refine clinical practice further. We also discuss some challenging aspects of managing this disease, particularly the complexity of acquired resistance mechanisms that develop under the selective pressure of targeted therapies and rational strategies being investigated to overcome them.

A comprehensive overview of the molecular features and therapeutic targets in BRAFV600E-mutant colorectal cancer

As one of the most prevalent digestive system tumours, colorectal cancer (CRC) poses a significant threat to global human health. With the emergence of immunotherapy and target therapy, the prognosis for the majority of CRC patients has notably improved. However, the subset of patients with BRAF exon 15 p.V600E mutation (BRAFV600E) has not experienced remarkable benefits from these therapeutic advancements. Hence, researchers have undertaken foundational investigations into the molecular pathology of this specific subtype and clinical effectiveness of diverse therapeutic drug combinations. This review comprehensively summarised the distinctive molecular features and recent clinical research advancements in BRAF-mutant CRC. To explore potential therapeutic targets, this article conducted a systematic review of ongoing clinical trials involving patients with BRAFV600E-mutant CRC.

Utility of Circulating Tumor DNA Assessment in Characterizing Recurrence Sites after Optimal Resection for Metastatic Colorectal Cancer

BACKGROUND

Plasma circulating tumor DNA (ctDNA) is a promising biomarker for metastatic colorectal cancer (mCRC); however, its role in characterizing recurrence sites after mCRC resection remains poorly understood. This single-institution study investigated the timing of ctDNA detection and its levels in the context of recurrence at different sites after mCRC resection.

STUDY DESIGN

Patients who underwent optimal resection of CRC metastases involving the peritoneum, distant lymph nodes, or liver, with serial postoperative tumor-informed ctDNA assessments (Signatera) were included. Recurrence sites, as defined by surveillance imaging or laparoscopy, were categorized as peritoneal-only and other distant sites (liver, lung, lymph nodes, or body wall).

RESULTS

Among the 31 included patients, ctDNA was detected in all 26 (83.4%) patients with postoperative recurrence and was persistently undetectable in 5 patients who did not experience recurrence. At 3 months postsurgery, ctDNA was detected in 2 (25%) of 8 patients with peritoneal-only recurrence and 17 (94.4%) of 18 patients with distant recurrence (p < 0.001). Beyond 3 months, ctDNA was detected in the remaining 6 patients with peritoneal-only disease and 1 patient with distant disease. ctDNA detection preceded the clinical diagnosis of recurrence by a median of 9 weeks in both groups. At recurrence, peritoneal-only recurrent cases exhibited lower ctDNA levels (median 0.4 mean tumor molecules/mL, interquartile range 0.1 to 0.8) compared with distant recurrence (median 5.5 mean tumor molecules/mL, interquartile range 0.8 to 33.3, p = 0.004).

CONCLUSIONS

Peritoneal-only recurrence was associated with delayed ctDNA detection and low levels of ctDNA after optimal resection for mCRC. ctDNA testing may effectively characterize recurrence sites and may help guide subsequent treatments specific to the disease sites involved.

Small-molecule drugs of colorectal cancer: Current status and future directions

Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the world's fourth most deadly cancer. CRC, as a genetic susceptible disease, faces significant challenges in optimizing prognosis through optimal drug treatment modalities. In recent decades, the development of innovative small-molecule drugs is expected to provide targeted interventions that accurately address the different molecular characteristics of CRC. Although the clinical application of single-target drugs is limited by the heterogeneity and high metastasis of CRC, novel small-molecule drug treatment strategies such as dual/multiple-target drugs, drug repurposing, and combination therapies can help overcome these challenges and provide new insights for improving CRC treatment. In this review, we focus on the current status of a range of small molecule drugs that are being considered for CRC therapy, including single-target drugs, dual/multiple-target drugs, drug repurposing and combination strategies, which will pave the way for targeting CRC vulnerabilities with small-molecule drugs in future personalized treatment.

Biomarkers in Cancer Detection, Diagnosis, and Prognosis

Biomarkers are vital in healthcare as they provide valuable insights into disease diagnosis, prognosis, treatment response, and personalized medicine. They serve as objective indicators, enabling early detection and intervention, leading to improved patient outcomes and reduced costs. Biomarkers also guide treatment decisions by predicting disease outcomes and facilitating individualized treatment plans. They play a role in monitoring disease progression, adjusting treatments, and detecting early signs of recurrence. Furthermore, biomarkers enhance drug development and clinical trials by identifying suitable patients and accelerating the approval process. In this review paper, we described a variety of biomarkers applicable for cancer detection and diagnosis, such as imaging-based diagnosis (CT, SPECT, MRI, and PET), blood-based biomarkers (proteins, genes, mRNA, and peptides), cell imaging-based diagnosis (needle biopsy and CTC), tissue imaging-based diagnosis (IHC), and genetic-based biomarkers (RNAseq, scRNAseq, and spatial transcriptomics).

The Impact of BRAF Mutation Status on Survival Outcomes and Treatment Patterns among Metastatic Colorectal Cancer Patients in Alberta, Canada

Colorectal cancer presents via multiple different clinical phenotypes that can arise from a variety of different genetic and molecular alterations. The aim of this study was to describe survival outcomes and treatment patterns of metastatic colorectal cancer (mCRC) patients by v-raf murine sarcoma viral oncogene homolog B1 (BRAF) mutation status. The Alberta Cancer Registry was used to identify all patients >18 years old who had been diagnosed with mCRC in Alberta between 1 January 2017 and 31 December 2019 and had received at least one cycle of systemic therapy. Treatment patterns were compared between wild-type and mutant BRAF mCRC patients. Cox regression models and Kaplan-Meier curves were created to assess survival differences by both treatment pattern and BRAF status. A total of 488 patients were identified with mCRC, of which 42 (11.4%) were confirmed to have a BRAF mutation. The most common first-line treatment regimen was either capecitabine and oxaliplatin (CAPOX) or leucovorin calcium (folinic acid), fluorouracil, and oxaliplatin (FOLFOX). The median overall survival for mCRC patients was 20.01 months. Mutant BRAF patients had a median survival of 8.21 months compared to 20.03 months among those with wild-type BRAF. BRAF mutations among mCRC patients are associated with a considerably poor prognosis, reinforcing the need for clinical BRAF testing among newly diagnosed patients to better understand their prognosis.

Current Practices in Hepatic Artery Infusion (HAI) Chemotherapy: An International Survey of the HAI Consortium Research Network

BACKGROUND

An increasing number of hepatic artery infusion (HAI) programs have been established worldwide. Practice patterns for this complex therapy across these programs have not been reported. This survey aimed to identify current practice patterns in HAI therapy with the long-term goal of defining best practices and performing prospective studies.

METHODS

Using SurveyMonkeyTM, a 28-question survey assessing current practices in HAI was developed by 12 HAI Consortium Research Network (HCRN) surgical oncologists. Content analysis was used to code textual responses, and the frequency of categories was calculated. Scores for rank-order questions were generated by calculating average ranking for each answer choice.

RESULTS

Thirty-six (72%) HCRN members responded to the survey. The most common intended initial indications for HAI at new programs were unresectable colorectal liver metastases (uCRLM; 100%) and unresectable intrahepatic cholangiocarcinoma (uIHC; 56%). Practice patterns evolved such that uCRLM (94%) and adjuvant therapy for CRLM (adjCRLM; 72%) have become the most common current indications for HAI at established centers. Referral patterns for pump placement differed between uCRLM and uIHC, with most patients referred while receiving second- and first-line therapy, respectively, with physicians preferring to evaluate patients for HAI while receiving first-line therapy for CRLM. Concern for extrahepatic disease was ranked as the most important factor when considering a patient for HAI.

CONCLUSIONS

Indication and patient selection factors for HAI therapy are relatively uniform across most HCRN centers. The increasing use of adjuvant HAI therapy and overall consistency of practice patterns among HCRN centers provides a robust environment for prospective data collection and randomized clinical trials.

Beyond EGFR inhibitors in advanced colorectal cancer: Targeting BRAF and HER2

The addition of antiepidermal growth factor receptor (EGFR) monoclonal antibodies, cetuximab or panitumumab, to conventional chemotherapy has improved clinical outcomes for rat sarcoma virus (RAS) wild-type advanced colorectal cancer patients, however, durable responses and 5-year overall survival rates remain limited. BRAF V600E somatic mutation and human epidermal growth factor receptor (HER2) amplification/overexpression have been separately implicated in primary resistance to anti-EGFR therapeutic strategies via aberrant activation of the mitogen-activated protein kinase (MAPK) signaling pathway, resulting in poorer outcomes. In addition to being a negative predictive biomarker for anti-EGFR therapy, BRAF V600E mutation and HER2 amplification/overexpression serve as positive predictors of response to therapies targeting these respective tumor promoters. This review will highlight key clinical studies that support the rational use of v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) and HER2-targeted therapies, often in combination with other targeted agents, cytotoxic chemotherapy, and immune checkpoint inhibitors. We discuss current challenges with BRAF and HER2-targeted therapies in metastatic colorectal cancer and potential opportunities for improvement.

Ongoing complete response after treatment cessation with dabrafenib, trametinib, and cetuximab as third-line treatment in a patient with advanced BRAFV600E mutated, microsatellite-stable colon cancer: A case report and literature review

Metastatic BRAFV600E mutated colorectal cancer is associated with poor overall survival and modest effectiveness to standard therapies. Furthermore, survival is influenced by the microsatellite status. Patients with microsatellite-stable and BRAFV600E mutated colorectal cancer have the worst prognosis under the wide range of genetic subgroups in colorectal cancer. Herein, we present a patient case of an impressive therapeutic efficacy of dabrafenib, trametinib, and cetuximab as later-line therapy in a 52-year-old woman with advanced BRAFV600E mutated, microsatellite-stable colon cancer. This patient achieved a complete response after 1 year of triple therapy. Due to skin toxicity grade 3 and recurrent urinary tract infections due to mucosal toxicity, a therapy de-escalation to dabrafenib and trametinib was performed, and the double therapy was administered for further 41 months with ongoing complete response. For 1 year, the patient was off therapy and is still in complete remission.

BRAF V600E and RNF43 Co-mutations Predict Patient Outcomes With Targeted Therapies in Real-World Cases of Colorectal Cancer

Anti-BRAF/EGFR therapy is approved for metastatic colorectal cancer (mCRC) with BRAFV600E mutations, although not all patients respond. Novel recent findings indicate the potential of RNF43 mutations to predict outcomes in patients with BRAF-mutated microsatellite stable (MSS) mCRC treated with anti-BRAF/EGFR therapy. This study aimed to independently and rapidly validate BRAFV600E/RNF43 co-mutations as predictive biomarkers of benefit to anti-EGFR/BRAF therapy. Clinical data were derived from electronic health record data from ~280 US cancer clinics between January 2011 and March 2022 from the Flatiron Health-Foundation Medicine real-world clinico-genomic mCRC database. Real-world cases of BRAFV600E-mutated mCRC, with patients receiving anti-BRAF/EGFR therapy (n = 49), were included. Patients who were MSS, with RNF43 mutations, had favorable progression-free survival (hazard ratio [HR] 0.29; 95% CI [CI], 0.13-0.65) and overall survival (HR 0.32, 95% CI, 0.12-0.84) compared with wild type. No difference in outcomes was observed between patient groups with RNF43-mutant versus wild-type receiving standard-of-care chemotherapy. BRAFV600E/RNF43 co-mutations predict mCRC anti-BRAF/EGFR outcomes in diverse clinical settings.

A Phase Ib/II Trial of Combined BRAF and EGFR Inhibition in BRAF V600E Positive Metastatic Colorectal Cancer and Other Cancers: The EVICT (Erlotinib and Vemurafenib In Combination Trial) Study

PURPOSE

BRAF V600E mutant metastatic colorectal cancer represents a significant clinical problem, with combination approaches being developed clinically with oral BRAF inhibitors combined with EGFR-targeting antibodies. While compelling preclinical data have highlighted the effectiveness of combination therapy with vemurafenib and small-molecule EGFR inhibitors, gefitinib or erlotinib, in colorectal cancer, this therapeutic strategy has not been investigated in clinical studies.

PATIENTS AND METHODS

We conducted a phase Ib/II dose-escalation/expansion trial investigating the safety/efficacy of the BRAF inhibitor vemurafenib and EGFR inhibitor erlotinib.

RESULTS

Thirty-two patients with BRAF V600E positive metastatic colorectal cancer (mCRC) and 7 patients with other cancers were enrolled. No dose-limiting toxicities were observed in escalation, with vemurafenib 960 mg twice daily with erlotinib 150 mg daily selected as the recommended phase II dose. Among 31 evaluable patients with mCRC and 7 with other cancers, overall response rates were 32% [10/31, 16% (5/31) confirmed] and 43% (3/7), respectively, with clinical benefit rates of 65% and 100%. Early ctDNA dynamics were predictive of treatment efficacy, and serial ctDNA monitoring revealed distinct patterns of convergent genomic evolution associated with acquired treatment resistance, with frequent emergence of MAPK pathway alterations, including polyclonal KRAS, NRAS, and MAP2K1 mutations, and MET amplification.

CONCLUSIONS

The Erlotinib and Vemurafenib In Combination Trial study demonstrated a safe and novel combination of two oral inhibitors targeting BRAF and EGFR. The dynamic assessment of serial ctDNA was a useful measure of underlying genomic changes in response to this combination and in understanding potential mechanisms of resistance.

Survival comparison of first-line treatment regimens in patients with braf-mutated advanced colorectal cancer: a multicenter retrospective study

BACKGROUND

Patients with V-Raf murine sarcoma viral oncogene homolog B1 (BRAF) V600E-mutated advanced colorectal cancer (CRC) have a poor prognosis, and treatment options that can improve outcome are still under investigation. The purpose of this study was to discuss the differences of overall survival (OS) and progression-free survival (PFS) between patients with BRAF V600E-mutated advanced CRC who were treated with chemotherapy alone and chemotherapy combined with targeted therapy in advanced first-line therapy.

METHODS

Grouping of 61 patients according to first-line treatment regimen (chemotherapy alone/chemotherapy combined with bevacizumab). Kaplan-Meier method and log-rank test were used to compare OS and PFS. Cox proportional hazards regression model was used to measure the risk of first-line medication therapies while correcting for confounding factors that may affect PFS and OS.

RESULTS

There was no significant difference in OS between patients treated with chemotherapy alone and those treated with chemotherapy combined with bevacizumab (P = 0.93; HR, 1.027; 95% CI, 0.555-1.901). Likewise, there was no significant difference in PFS between the two groups (P = 0.29; HR, 0.734; 95% CI, 0.413-1.304). Subgroup analysis showed that OS and PFS of different treatment regimens were not significantly different among subgroups. Multivariate analysis suggested that surgical treatment of primary tumor (P = 0.001; HR, 0.326; 95% CI, 0.169-0.631) and presence of liver metastasis (P = 0.009; HR, 2.399; 95% CI, 1.242-4.635) may serve as independent prognostic indicators in patients with BRAF-mutated advanced CRC. Surgical treatment of the primary tumor (P = 0.041; HR, 0.523; 95% CI, 0.280-0.974) was significantly associated with PFS too.

CONCLUSION

For patients with BRAF V600E-mutated advanced CRC, chemotherapy alone did not differ significantly in OS and PFS compared with chemotherapy + bevacizumab for advanced first-line therapy. Chemotherapy combined with targeted therapy did not render a survival benefit to these patients, demonstrating that the importance of developing new treatment options for this population.

A reversible SRC-relayed COX2 inflammatory program drives resistance to BRAF and EGFR inhibition in BRAFV600E colorectal tumors

BRAF^V600E mutation confers a poor prognosis in metastatic colorectal cancer (CRC) despite combinatorial targeted therapies based on the latest understanding of signaling circuitry. To identify parallel resistance mechanisms induced by BRAF-MEK-EGFR co-targeting, we used a high-throughput kinase activity mapping platform. Here we show that SRC kinases are systematically activated in BRAF^V600E CRC following targeted inhibition of BRAF ± EGFR and that coordinated targeting of SRC with BRAF ± EGFR increases treatment efficacy in vitro and in vivo. SRC drives resistance to BRAF ± EGFR targeted therapy independently of ERK signaling by inducing transcriptional reprogramming through β-catenin (CTNNB1). The EGFR-independent compensatory activation of SRC kinases is mediated by an autocrine prostaglandin E₂ loop that can be blocked with cyclooxygenase-2 (COX2) inhibitors. Co-targeting of COX2 with BRAF + EGFR promotes durable suppression of tumor growth in patient-derived tumor xenograft models. COX2 inhibition represents a drug-repurposing strategy to overcome therapeutic resistance in BRAF^V600E CRC.

Recent and Future Strategies to Overcome Resistance to Targeted Therapies and Immunotherapies in Metastatic Colorectal Cancer

Colorectal cancer (CRC) is the third most common cause of cancer-related deaths worldwide, and 20% of patients with CRC present at diagnosis with metastases. The treatment of metastatic CRC is based on a fluoropyrimidine-based chemotherapy plus additional agents such as oxaliplatin and irinotecan. To date, on the basis of the molecular background, targeted therapies (e.g., monoclonal antibodies against epidermal growth factor receptor or inhibiting angiogenesis) are administered to improve the treatment of metastatic CRC. In addition, more recently, immunological agents emerged as effective in patients with a defective mismatch repair system. The administration of targeted therapies and immunotherapy lead to a significant increase in the survival of patients; however these drugs do not always prove effective. In most cases the lack of effectiveness is due to the development of primary resistance, either a resistance-inducing factor is already present before treatment or resistance is acquired when it occurs after treatment initiation. In this review we describe the most relevant targeted therapies and immunotherapies and expand on the reasons for resistance to the different approved or under development targeted drugs. Then we showed the possible mechanisms and drugs that may lead to overcoming the primary or acquired resistance in metastatic CRC.

TRESBIEN (OGSG 2101): encorafenib, binimetinib and cetuximab for early recurrent stage II/III BRAF V600E-mutated colorectal cancer

The BRAF V600E mutation accounts for approximately 5% of colorectal cancer (CRC) cases and is an extremely poor prognostic factor. However, there are no clear recommendations regarding first-line therapy for patients with early recurrent BRAF V600E-mutated CRC, during or after adjuvant chemotherapy. Recently, a novel combination of encorafenib, binimetinib and cetuximab, showed a higher response rate than standard chemotherapy in patients with BRAF V600E-mutated CRC. Here we describe our plan for the TRESBIEN study (OGSG 2101), which is an open-label, multicenter, single-arm, phase II study designed to evaluate whether encorafenib, binimetinib and cetuximab are effective for patients with early recurrent BRAF V600E-mutated colorectal cancer, during or after adjuvant chemotherapy. The planned number of subjects is 25.

WJOG13219G: The Efficacy and Safety of FOLFOXIRI or Doublet plus Anti-VEGF Therapy in Previously Untreated BRAFV600E Mutant Metastatic Colorectal Cancer: A Multi-Institutional Registry-Based Study (BRACELET Study)

BACKGROUND

The real-world survival benefit of FOLFOXIRI (fluorouracil, leucovorin, oxaliplatin, and irinotecan) plus anti-VEGF therapy (Triplet) over doublet chemotherapy (Doublet) remains controversial in patients with BRAF^V600E mutant metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

WJOG13219G was a multicenter, retrospective, registry-based study of patients with BRAF^V600E mutant mCRC who received first-line triplet or doublet chemotherapy from January 2014 to December 2019 in Japan. Inverse probability of treatment weighting (IPTW) was used to adjust for patient background.

RESULTS

The analysis included 79 and 91 patients in the Triplet and Doublet groups, respectively. The Triplet group was significantly younger and had better performance status. No statistical difference was noted in progression-free survival (PFS; HR, 0.82; 95% CI, 0.60-1.13; P = .22) and overall survival (OS; HR, 0.88; 95% CI, 0.62-1.25; P = .48) between both groups. IPTW analysis also showed no difference between the 2 groups in PFS (HR, 0.86; 95% CI, 0.69-1.08; P = .20) and OS (HR, 0.93; 95% CI, 0.73-1.20; P = .59). The Triplet and Doublet groups had an objective response rate of 53% and 41%, respectively (P = .10). At least one grade 3 or 4 adverse event was seen in 51 (65%) and 43 (47%) patients in the Triplet and Doublet groups, respectively, with the incidence of neutropenia being significantly higher in the former.

CONCLUSION

Triplet therapy had no survival benefit versus doublet therapy in the overall and IPTW cohorts or specific subgroups for real-world patients with BRAF^V600E mutant mCRC.

RNF43 mutations predict response to anti-BRAF/EGFR combinatory therapies in BRAFV600E metastatic colorectal cancer

Anti-BRAF/EGFR therapy was recently approved for the treatment of metastatic BRAF^V600E colorectal cancer (mCRC^BRAF-V600E). However, a large fraction of patients do not respond, underscoring the need to identify molecular determinants of treatment response. Using whole-exome sequencing in a discovery cohort of patients with mCRC^BRAF-V600E treated with anti-BRAF/EGFR therapy, we found that inactivating mutations in RNF43, a negative regulator of WNT, predict improved response rates and survival outcomes in patients with microsatellite-stable (MSS) tumors. Analysis of an independent validation cohort confirmed the relevance of RNF43 mutations to predicting clinical benefit (72.7% versus 30.8%; P = 0.03), as well as longer progression-free survival (hazard ratio (HR), 0.30; 95% confidence interval (CI), 0.12–0.75; P = 0.01) and overall survival (HR, 0.26; 95% CI, 0.10–0.71; P = 0.008), in patients with MSS-RNF43^mutated versus MSS-RNF43^wild-type tumors. Microsatellite-instable tumors invariably carried a wild-type-like RNF43 genotype encoding p.G659fs and presented an intermediate response profile. We found no association of RNF43 mutations with patient outcomes in a control cohort of patients with MSS-mCRC^BRAF-V600E tumors not exposed to anti-BRAF targeted therapies. Overall, our findings suggest a cross-talk between the MAPK and WNT pathways that may modulate the antitumor activity of anti-BRAF/EGFR therapy and uncover predictive biomarkers to optimize the clinical management of these patients.

The presence of inactivating mutations in RNF43, a negative regulator of WNT, in tumor cells predicts improved response rates and survival outcomes in patients with metastatic BRAF^V600E colorectal cancer treated with anti-BRAF/EGFR therapy.

Colon Cancer Pharmacogenetics: A Narrative Review

Currently, metastatic colon cancer is treated with monotherapeutic regimens such as folinic acid, fluorouracil, and oxaliplatin (FOLFOX), capecitabine and oxaliplatin (CapeOX), and leucovorin, fluorouracil, and irinotecan hydrochloride (FOLFIRI). Other treatments include biological therapies and immunotherapy with drugs such as bevacizumab, panitumumab, cetuximab, and pembrolizumab. After the research, it was found that some mutations make those treatments not as effective in all patients. In this bibliographic review, we investigated the pharmacogenetic explanations for how mutations in the genes coding for rat sarcoma virus (RAS) and rapidly accelerated fibrosarcoma (RAF) reduce the effectiveness of these treatments and allow the continued proliferation of tumors. Furthermore, we note that patients with mutations in the dihydropyrimidine dehydrogenase (DPDY) gene usually require lower doses of therapies such as 5-fluorouracyl (5-FU) and capecitabine to avoid severe adverse effects. Some other mutations in the thymidylate synthase gene (TSYM), methylenetetrahydrofolate reductase gene (MTHFR), and ATP binding cassette transporter B (ABCB1 and ABCB2) affect efficacy and security of the treatments. It is important to address the clinical implication of the oncologist in the study of gene mutations than can influence in the antitumoral response and safety of colon cancer treatments.

FBXW7 and Its Downstream NOTCH Pathway Could be Potential Indicators of Organ-Free Metastasis in Colorectal Cancer

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths globally. Metastasis is associated with a poor prognosis, yet the underlying molecular mechanism(s) remained largely unknown. In this study, a total of 85 CRC patients were included and the primary tumor lesions were evaluated by next-generation sequencing using a targeted panel for genetic aberrations. Patients were sub-divided according to their metastasis pattern into the non-organ metastases (Non-OM) and organ metastases (OM) groups. By comparing the genetic differences between the two groups, we found that mutations in FBXW7 and alterations in its downstream NOTCH signaling pathway were more common in the Non-OM group. Moreover, correlation analysis suggested that FBXW7 mutations were independent of other somatic alterations. The negative associations of alterations in FBXW7 and its downstream NOTCH signaling pathway with CRC organ metastasis were validated in a cohort of 230 patients in the TCGA CRC dataset. Thus, we speculated that the genomic alterations of FBXW7/NOTCH axis might be an independent negative indicator of CRC organ metastases.

Immune Profile of BRAF-Mutated Metastatic Colorectal Tumors with Good Prognosis after Palliative Chemotherapy

Background: BRAF-mutated colorectal cancers (BRAF-MT CRCs) are known to have poor prognoses. BRAF-MT CRC was reported to be possibly related to the immune-activated phenotype. Objectives: This study aimed to investigate the association between the immune microenvironment and prognosis of BRAF-MT CRC. Methods: We evaluated clinical outcomes and investigated the immune profile of the BRAF-MT CRC tumors using the multiplex immunohistochemistry of immune-related markers: cytokeratin, programmed death ligand-1 (PD-L1), programmed cell death protein-1 (PD-1), and a cluster of differentiation 8 (CD8). Results: Out of 2313 tumors, 123 were BRAF-MT tumors. Among them, 86 tumors with available tissue were included. Out of 86 patients, 75 patients were non-good responders (GR), whereas 11 patients were GR. Median progression-free survival after first-line chemotherapy (4.6 vs. 12.4 months, p = 0.008) and overall survival (11.8 vs. 45.0 months) were longer in the GR group (p < 0.001). Median CD8+ T cell (254.29 vs. 656.0, p = 0.092), PD-L1+ tumor cell (0.95 vs.15.56, p = 0.050), PD-L1+ stromal cell (3.17 vs. 72.38, p = 0.025), PD-L1+ tumor and stromal cell (5.08 vs. 74.92, p = 0.032), and PD-1+ stromal cell (45.08 vs. 325.40, p = 0.046) counts were greater in the GR group. Conclusion: The clinical outcomes of unselected patients with BRAF-MT CRC were generally similar to those in previous studies. Based on the immune profile analysis, higher PD-L1 expression and CD8-positive cell infiltration were observed in BRAF-MT tumors with a good prognosis.

Systematic review of randomised clinical trials and observational studies for patients with RAS wild-type or BRAFV600E-mutant metastatic and/or unresectable colorectal cancer

Approximately 8-10% of metastatic colorectal cancer (mCRC) tumours harbour BRAF^V600E mutations. Eleven randomised controlled trials (RCTs) and 24 non-RCTs were identified. Seven studies evaluated BRAF inhibitors. Single-agent BRAF inhibitors had minimal efficacy, whereas BRAF inhibitor plus anti-EGFR therapy improved outcomes. In BEACON CRC, overall survival (OS) was significantly longer for patients receiving encorafenib plus cetuximab ± binimetinib when compared with irinotecan/FOLFIRI plus cetuximab as second- and third-line therapy. Seven prospective non-RCTs reported worse OS and progression-free survival (PFS) for patients with BRAF^V600E-mutant vs BRAF wild-type mCRC. Eight RCTs reported that PFS and OS were generally shorter for patients with BRAF^V600E-mutant mCRC vs those with KRAS or RAS wild-type mCRC. Patients with BRAF^V600E-mutant mCRC have worse outcomes with conventional therapy vs patients with BRAF wild-type tumours. BRAF inhibitors in conjunction with anti-EGFR therapy improves outcomes for patients with BRAF^V600E-mutant mCRC vs conventional therapy or a BRAF inhibitor alone.

Exploring biological heterogeneity and implications on novel treatment paradigm in BRAF-mutant metastatic colorectal cancer

Approximatively 8-15% of patients with metastatic colorectal cancer (mCRC) harbor mutation in BRAF gene. Recent advances in molecular biology enabled a better knowledge of the molecular heterogeneity within BRAF mutant (BRAF^MT) CRCs, including high rate of overlapping with MSI-H status and detection of non-V600E mutations related to more favorable behavior. Treatment armamentarium has been rapidly growing in this subgroup and includes targeted combinations and immunotherapy for concomitant MSI-H patients, thereby making BRAF^MT mCRC an innovative model for precision oncology. Nevertheless, duration of responses to targeted strategies remains unsatisfactory due to the development of secondary resistance, which is currently the field of major clinical research on BRAF^MT mCRC. This review explores the molecular, clinical and therapeutic landscape of BRAF^MT mCRC as well as an update on current treatment strategies and future perspectives in light of the heterogeneity of BRAF-mutated disease. Furthermore, a novel treatment algorithm for BRAF^MT mCRC will be proposed.

Colorectal cancer carcinogenesis: From bench to bedside

Colorectal cancer (CRC) remains one of the main causes of cancer death in developed countries. Yet, it is potentially preventable, by removing the precursor lesions - adenomas or serrated lesions. Several studies proved that this intervention reduces CRC mortality and that the first colonoscopy’s results can guide surveillance strategies. More recently, it became clear that several carcinogenesis pathways may lead to sporadic CRC. CRC is a heterogeneous disease, characterized by multiple molecular subtypes. Three main pathways have been implicated in the development of CRC: Chromosomal instability, microsatellite instability, and the “serrated” pathways, with overlapping features between them. This and other molecular and genetic based CRC classifications are known to have clinical implications, spanning from familial risk assessment to therapy choices. The authors review basic science data and provide insight on current implications for the management of patients with CRC.

BRAF, MEK, and EGFR Triplet Inhibitors as Salvage Therapy in BRAF-Mutated Metastatic Colorectal Cancer-A Case Series Study Target Therapy of BRAF-Mutated mCRC

Backgroundand objectives: Patients with BRAF-mutated metastatic colorectal cancer have considerably poorer responses to conventional systemic treatment. The real-world effects of triplet therapy with BRAF, mitogen-activated protein kinase kinase, and epidermal growth factor receptor inhibitors in Asia have not been well-reported. Materials and Methods: This single-center case series included patients with BRAF-mutated metastatic colorectal cancer undergoing triplet therapy after failure of prior systemic treatment from 2016 to 2020. The primary outcome was progression-free survival, and secondary outcomes were overall survival, response rate, disease control rate, and adverse events. Results: Nine eligible patients with BRAF-mutated metastatic colorectal cancer receiving triplet therapy were enrolled, with a median follow-up time of 14.5 months (range, 1-26). Most patients (88.8%) had two or more prior systemic treatments, and the triplet regimen was mainly dabrafenib, trametinib, and panitumumab. The overall response rate and disease control rate were 11.1% and 33.3%, respectively. Median progression-free survival and overall survival were 2.9 and 7.4 months, respectively, and a trend toward better overall survival was found with left-sided metastatic colorectal cancer compared with right-sided disease (9.2 vs. 6.9 months, p = 0.093). Adverse events were mostly Grade 1-2, including nausea, hypertension, gastrointestinal symptoms, and skin disorders. Conclusions: In this single-center case series, triplet therapy with BRAF, mitogen-activated protein kinase kinase, and epidermal growth factor receptor inhibitors in BRAF-mutated metastatic colorectal cancer had an acceptable safety profile and reasonable efficacy.

Modeling of Personalized Treatments in Colon Cancer Based on Preclinical Genomic and Drug Sensitivity Data

Simple Summary

This experimental preclinical study developed a strategy to identify signatures for the personalized treatment of colon cancer focusing on target-specific drug combinations. Tumor growth inhibition was analyzed in a preclinical phase II study using 25 patient-derived xenograft models (PDX) treated with drug combinations blocking alternatively activated oncogenic pathways. Results reveal an improved response by combinatorial treatment in some defined molecular subgroups and potential alternative treatment options in KRAS- and BRAF-mutated colon cancer.

Abstract

The current standard therapies for advanced, recurrent or metastatic colon cancer are the 5-fluorouracil and oxaliplatin or irinotecan schedules (FOxFI) +/− targeted drugs cetuximab or bevacizumab. Treatment with the FOxFI cytotoxic chemotherapy regimens causes significant toxicity and might induce secondary cancers. The overall low efficacy of the targeted drugs seen in colon cancer patients still is hindering the substitution of the chemotherapy. The ONCOTRACK project developed a strategy to identify predictive biomarkers based on a systems biology approach, using omics technologies to identify signatures for personalized treatment based on single drug response data. Here, we describe a follow-up project focusing on target-specific drug combinations. Background for this experimental preclinical study was that, by analyzing the tumor growth inhibition in the PDX models by cetuximab treatment, a broad heterogenic response from complete regression to tumor growth stimulation was observed. To provide confirmation of the hypothesis that drug combinations blocking alternatively activated oncogenic pathways may improve therapy outcomes, 25 models out of the well-characterized ONCOTRACK PDX panel were subjected to treatment with a drug combination scheme using four approved, targeted cancer drugs.

Taiwan Society of Colon and Rectal Surgeons Consensus on mCRC Treatment

Therapeutic options for metastatic CRC (mCRC) have changed significantly in recent years, greatly increasing the complexity of therapeutic decision-making. Although oncology guidelines have helped improve the care process, guidelines may also limit the flexibility to individualize in-clinic decision-making. This consensus paper addresses specific gaps in the current international guidelines to assist Taiwanese colon and rectal experts make specific therapeutic choices. Over 3 years and three meetings with selected experts on "real-world" Taiwanese practice patterns for mCRC, consensus was achieved. The experts also discussed specific questions during in-depth one-on-one consultation. Outcomes of the discussion were then correlated with published evidence by an independent medical writer. The final consensus includes clinically implementable recommendations to provide guidance in treating Taiwanese mCRC patients. The consensus includes criteria for defining fit and unfit intensive treatment patients, treatment goals, treatment considerations of molecular profiles, treatment consideration, and optimal treatment choices between different patient archetypes, including optimal treatment options based on RAS, BRAF, and microsatellite instability (MSI) status. This consensus paper is the second in the Taiwan Society of Colon and Rectal Surgeons (TSCRS) Consensus series to address unmet gaps in guideline recommendations in lieu of Taiwanese mCRC management. Meticulous discussions with experts, the multidisciplinary nature of the working group, and the final drafting of the consensus by independent medical professionals have contributed to the strong scientific value of this consensus.

BRAF testing in metastatic colorectal carcinoma and novel, chemotherapy-free therapeutic options

In the past 25 years, treatment of metastatic colorectal cancer (mCRC) has undergone profound changes. The approval of newer chemotherapeutics such as irinotecan and oxaliplatin was followed in 2005 by the first targeted therapies, for example, monoclonal antibodies directed against the epidermal growth factor receptor (EGFR), as cetuximab and panitumumab, or the angiogenesis inhibitors bevacizumab, ramucirumab, and aflibercept. With the rapidly progressing molecular characterization of mCRC in the last 10 years and the classification of the disease in four consensus subtypes, further changes are emerging, which will promote, among other things, the introduction of protein-kinase inhibitors developed for specific molecular aberrations as well as immune checkpoint inhibitors into the treatment algorithm.Thorough molecular pathologic testing is indispensable today for guideline-compliant treatment of mCRC patients. In addition to RAS testing as a precondition for the therapy decision with regard to cetuximab and panitumumab, BRAF testing is of considerable relevance to allow decision making with regard to the newly approved chemotherapy-free combination of the BRAF inhibitor encorafenib and cetuximab in cases where a BRAF-V600E mutation is detected. Additional diagnostic tests should also include genome instability (microsatellite instability). Overall, more and more molecular alterations need to be investigated simultaneously, so that the use of focused next-generation sequencing is increasingly recommended.This overview describes the prognostic relevance of BRAF testing in the context of molecular pathologic diagnostics of mCRC, presents new treatment options for BRAF-mutated mCRC patients, and explains which modern DNA analytical and immunohistochemical methods are available to detect BRAF mutations in mCRC patients.

[BRAF-V600E testing in metastatic colorectal cancer and new, chemotherapy-free therapy options. German version]

In the past 25 years, treatment of metastatic colorectal cancer (mCRC) has undergone profound changes. The approval of newer chemotherapeutics such as irinotecan and oxaliplatin was followed in 2005 by the first targeted therapies, for example, monoclonal antibodies directed against the epidermal growth factor receptor (EGFR), as cetuximab and panitumumab, or the angiogenesis inhibitors bevacizumab, ramucirumab, and aflibercept. With the rapidly progressing molecular characterization of mCRC in the last 10 years and the classification of the disease in four consensus subtypes, further changes are emerging, which will promote, among other things, the introduction of protein-kinase inhibitors developed for specific molecular aberrations as well as immune checkpoint inhibitors into the treatment algorithm.Thorough molecular pathologic testing is indispensable today for guideline-compliant treatment of mCRC patients. In addition to RAS testing as a precondition for the therapy decision with regard to cetuximab and panitumumab, BRAF testing is of considerable relevance to allow decision making with regard to the newly approved chemotherapy-free combination of the BRAF inhibitor encorafenib and cetuximab in cases where a BRAF-V600E mutation is detected. Additional diagnostic tests should also include genome instability (microsatellite instability). Overall, more and more molecular alterations need to be investigated simultaneously, so that the use of focused next-generation sequencing is increasingly recommended.This overview describes the prognostic relevance of BRAF testing in the context of molecular pathologic diagnostics of mCRC, presents new treatment options for BRAF-mutated mCRC patients, and explains which modern DNA analytical and immunohistochemical methods are available to detect BRAF mutations in mCRC patients.

Encorafenib Plus Cetuximab as a New Standard of Care for Previously Treated BRAF V600E-Mutant Metastatic Colorectal Cancer: Updated Survival Results and Subgroup Analyses from the BEACON Study

BEACON CRC evaluated encorafenib plus cetuximab with or without binimetinib versus investigators' choice of irinotecan or FOLFIRI plus cetuximab in patients with BRAFV600E–mutant metastatic colorectal cancer (mCRC), after progression on 1-2 prior regimens. In the previously reported primary analysis, encorafenib, binimetinib plus cetuximab (ENCO/BINI/CETUX; triplet) and encorafenib plus cetuximab (ENCO/CETUX; doublet) regimens improved overall survival (OS) and objective response rate (ORR; by blinded central review) versus standard of care. The purpose of this analysis was to report updated efficacy and safety data.

Precision oncology in metastatic colorectal cancer - from biology to medicine

Remarkable progress has been made in the development of biomarker-driven targeted therapies for patients with multiple cancer types, including melanoma, breast and lung tumours, although precision oncology for patients with colorectal cancer (CRC) continues to lag behind. Nonetheless, the availability of patient-derived CRC models coupled with in vitro and in vivo pharmacological and functional analyses over the past decade has finally led to advances in the field. Gene-specific alterations are not the only determinants that can successfully direct the use of targeted therapy. Indeed, successful inhibition of BRAF or KRAS in metastatic CRCs driven by activating mutations in these genes requires combinations of drugs that inhibit the mutant protein while at the same time restraining adaptive resistance via CRC-specific EGFR-mediated feedback loops. The emerging paradigm is, therefore, that the intrinsic biology of CRC cells must be considered alongside the molecular profiles of individual tumours in order to successfully personalize treatment. In this Review, we outline how preclinical studies based on patient-derived models have informed the design of practice-changing clinical trials. The integration of these experiences into a common framework will reshape the future design of biology-informed clinical trials in this field.

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.

Exploring clinical and gene expression markers of benefit from FOLFOXIRI/bevacizumab in patients with BRAF-mutated metastatic colorectal cancer: Subgroup analyses of the TRIBE2 study

BACKGROUND

Recent data from the TRIBE2 study have failed to suggest a higher magnitude of benefit from upfront FOLFOXIRI/bevacizumab in patients with BRAF-mutant metastatic colorectal cancer (mCRC) as previously reported in the TRIBE study.

PATIENTS AND METHODS

Clinical characteristics and gene expression signatures of patients with BRAF-mutant mCRC enrolled in the TRIBE2 study were evaluated with the aim of understanding that patients may derive benefit from the intensification of the upfront chemotherapy.

RESULTS

Of 46 BRAF-mutant tumour samples analysed, 24 (52%) and 22 (48%) were classified as BM1 and BM2, respectively, and 27 (59%) and 19 (41%) were assigned to ligand-independent (LI) and ligand-dependent (LD) Wnt pathway subgroups, respectively. No prognostic impact was shown for both BM1/BM2 and LI/LD subtypes. No interaction was evident between BM1/BM2 or LI/LD signatures and the benefit provided by FOLFOXIRI/bevacizumab. Significant interaction effect was evident in terms of progression-free survival between treatment arm and primary tumour sidedness (P = 0.05) and Eastern Cooperative Oncology Group performance status (ECOG-PS; P < 0.001).

CONCLUSIONS

Gene expression analysis failed to identify patients with BRAF-mutant mCRC candidate to upfront FOLFOXIRI/bevacizumab. ECOG-PS >0 and left-sidedness seem associated with no benefit from the intensified treatment.

Impact of BRAF mutations on clinical outcomes following liver surgery for colorectal liver metastases: An updated meta-analysis

BACKGROUND

Data regarding clinical outcomes of patients undergoing hepatic resection for BRAF-mutated colorectal liver metastases (CRLM) are scarce. Most of the studies report an impaired median overall survival (OS) in BRAF-mutated patients, but controversial Results regarding both recurrence-free survival (RFS) and recurrence patterns. The purpose of this updated meta-analysis was to better precise the impact of BRAF mutations on clinical outcomes following liver surgery for CRLM study, especially on recurrence.

METHODS

A systematic literature review was performed to identify articles reporting clinical outcomes including both OS and RFS, recurrence patterns, and clinicopathological details of patients who underwent complete liver resection for CRLM, stratified according to BRAF mutational status.

RESULTS

Thirteen retrospective studies, including 5192 patients, met the inclusion criteria. The analysis revealed that both OS (OR = 1.981; 95% CI = [1.613-2.432]) and RFS (OR = 1.49; 95% CI [1.01-2.21]) were impaired following liver surgery for CRLM in BRAF-mutated patients. Risks of both hepatic (OR = 0.42; 95% CI [0.18-0.98]) and extrahepatic recurrences (OR = 0.53; 95% CI [0.33-0.83] were significantly higher in BRAF-mutated patients. These patients tended to have higher rates of right-sided colon primary tumors, primary positive lymph nodes, and multiple CRLM.

CONCLUSIONS

This meta-analysis confirms that BRAF mutations impair both OS and RFS following liver surgery. Therefore, BRAF mutational status should probably be included in further prognostic scores for the assessment of the expected clinical outcomes following surgery for CRLM.

UGT1A1 Polymorphism for Irinotecan Dose Escalation in Patients with BRAF-Mutated Metastatic Colorectal Cancer Treated with First-Line Bevacizumab and FOLFIRI

Background

Patients with metastatic colorectal cancer (mCRC) and BRAF V600E mutation have a poor prognosis, with a median progression-free survival (PFS) of only 5–7 months after initial therapy. The current standard first-line chemotherapy for these patients includes FOLFOX or FOLFIRI plus bevacizumab. In this study, we explored the effects and oncological outcomes of UGT1A1 polymorphism for irinotecan escalation in patients with BRAF-mutated mCRC. Patients and Methods. This retrospective study included 17 patients with BRAF-mutated mCRC between April 2016 and December 2019. UGT1A1 genotyping was performed on all patients prior to initiating bevacizumab plus FOLFIRI chemotherapy. The primary endpoint was PFS, and the secondary endpoints were toxicity, response rate, disease control rate, and overall survival (OS).

Results

Fifteen and two patients had UGT1A1 1∗/1∗ and 1∗/28∗, respectively. Eight underwent irinotecan dose escalation with tolerable adverse effects (AEs), and nine maintained an irinotecan dose of 180 mg/m² or required deescalation to 150 mg/m² due to intolerable AEs. After a median follow-up period of 15.7 (range, 3–54) months, the median PFS and OS were 9.4 and 15.7 months, respectively. Grade 3/4 AEs were observed in three (6%) patients. The disease control and partial response rates were 64.7% and 11.8%, respectively, indicating that most patients (14, 82.3%) could maintain this as a first-line line therapy with stable disease or proceed to second-line therapy if disease progression occurred, thereby maintaining acceptable performance status.

Conclusions

The oncological outcomes of patients with BRAF-mutated mCRC treated using FOLFIRI plus bevacizumab with irinotecan dose escalation as a first-line therapy are acceptable with tolerable AEs; this may be a feasible treatment option in such patients. Pretherapeutic UGT1A1 genotyping-guided dose adjustment can achieve favorable outcomes.

Defining and Targeting BRAF Mutations in Solid Tumors

OPINION STATEMENT

BRAF mutations are present in up to 8% of human cancers, and comprise a viable therapeutic target in many patients harboring these mutations. Specific BRAF-targeted therapies, such as vemurafenib, dabrafenib, and encorafenib, have transformed treatment of many BRAF-mutated cancers, producing meaningful clinical benefit with more tolerable safety profiles compared to prior standard-of-care treatments. BRAF inhibitors were first approved for use in metastatic melanoma, although resistance almost always limited their long-term effectiveness. Combination therapy with BRAF and MEK inhibitors has proven effective in delaying the onset of resistance, and produces additional clinical benefit across cancers. Although not promising initially in treatment of BRAF-mutated colorectal carcinoma, BRAF inhibitors in colorectal cancer were successfully combined with EGFR inhibitors, resulting in significant treatment response. Refining the use of BRAF and MEK inhibitors in less common tumor types (and for non-V600 mutations) and delaying the development of resistance remain pertinent future considerations in treating BRAF-mutated cancers. In this review, we will discuss the prevalence of BRAF mutations across human cancers and evidence on the efficacy and safety of current management strategies for various BRAF-mutant solid tumors.

Randomized Trial of Irinotecan and Cetuximab With or Without Vemurafenib in BRAF-Mutant Metastatic Colorectal Cancer (SWOG S1406)

PURPOSE

BRAFV600E mutations are rarely associated with objective responses to the BRAF inhibitor vemurafenib in patients with metastatic colorectal cancer (CRC). Blockade of BRAFV600E by vemurafenib causes feedback upregulation of EGFR, whose signaling activities can be impeded by cetuximab.

METHODS

One hundred six patients with BRAFV600E-mutated metastatic CRC previously treated with one or two regimens were randomly assigned to irinotecan and cetuximab with or without vemurafenib (960 mg PO twice daily).

RESULTS

Progression-free survival, the primary end point, was improved with the addition of vemurafenib (hazard ratio, 0.50, P = .001). The response rate was 17% versus 4% (P = .05), with a disease control rate of 65% versus 21% (P < .001). A decline in circulating tumor DNA BRAFV600E variant allele frequency was seen in 87% versus 0% of patients (P < .001), with a low incidence of acquired RAS alterations at the time of progression. RNA profiling suggested that treatment benefit did not depend on previously established BRAF subgroups or the consensus molecular subtype.

CONCLUSION

Simultaneous inhibition of EGFR and BRAF combined with irinotecan is effective in BRAFV600E-mutated CRC.

The EMA assessment of encorafenib in combination with cetuximab for the treatment of adult patients with metastatic colorectal carcinoma harbouring the BRAFV600E mutation who have received prior therapy

On 2 June 2020, a marketing authorisation valid through the European Union (EU) was issued for encorafenib in combination with cetuximab in adult patients with metastatic colorectal carcinoma (mCRC) with the BRAFV600E mutation who had received prior systemic therapy. Encorafenib plus cetuximab was evaluated in a randomised phase III trial of encorafenib plus binimetinib plus cetuximab versus encorafenib plus cetuximab versus cetuximab plus irinotecan or FOLFIRI (control arm) to adult patients with BRAFV600E mCRC who had received prior therapy for metastatic disease. The median overall survival was 9.3 months [95% confidence interval (CI): 8.05-11.30] versus 5.88 months (95% CI: 5.09-7.10) for encorafenib plus cetuximab (doublet) versus the control arm, respectively [hazard ratio (HR) 0.61, 95% CI: 0.48-0.77]. Progression-free survival (PFS) was 4.27 months (95% CI: 4.07-5.45) versus 1.54 months (95% CI: 1.48-1.91) (HR 0.44; 95% CI: 0.35-0.55). The most frequent adverse events in patients receiving encorafenib plus cetuximab were fatigue, nausea, diarrhoea, acneiform dermatitis, abdominal pain, arthralgia, decreased appetite, vomiting and rash. The aim of this manuscript is to summarise the scientific review of the application leading to regulatory approval in the EU.

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Encorafenib was approved in combination with cetuximab for patients with previously treated BRAF plus colorectal carcinoma.

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The original submission also included binimetinib, which was withdrawn during the procedure.

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The benefit–risk balance was considered positive due to a large benefit on PFS and strong biologic rationale.

The Evolutionary Landscape of Treatment for BRAFV600E Mutant Metastatic Colorectal Cancer

The BRAFV600E mutation is found in 8-10% of metastatic colorectal cancer (mCRC) patients and it is recognized as a poor prognostic factor with a median overall survival inferior to 20 months. At present, besides immune checkpoint inhibitors (CPIs) for those tumors with concomitant MSI-H status, recommended treatment options include cytotoxic chemotherapy + anti-VEGF in the first line setting, and a combination of EGFR and a BRAF inhibitor (cetuximab plus encorafenib) in second line. However, even with the latter targeted approach, acquired resistance limits the possibility of more than an incremental benefit and survival is still dismal. In this review, we discuss current treatment options for this subset of patients and perform a systematic review of ongoing clinical trials. Overall, we identified six emerging strategies: targeting MAPK pathway (monotherapy or combinations), targeting MAPK pathway combined with cytotoxic agents, intensive cytotoxic regimen combinations, targeted agents combined with CPIs, oxidative stress induction, and cytotoxic agents combined with antiangiogenic drugs and CPIs. In the future, the integration of new therapeutic strategies targeting key players in the BRAFV600E oncogenic pathways with current treatment approach based on cytotoxic chemotherapy and surgery is likely to redefine the treatment landscape of these CRC patients.

New advances in the clinical management of RAS and BRAF mutant colorectal cancer patients

INTRODUCTION

In colorectal carcinogenesis, genetic alterations in RAS and BRAF oncogenes play an important role for cancer initiation and/or progression and represent a key focus in the search for targeted therapies. Despite many years of research and a great amount of studies, until very recently this pathway was considered extremely hard to downregulate to obtain a significant clinical impact in colorectal cancer patients. But better times are coming with the advent of new promising drugs and combinations strategies.

AREAS COVERED

In this review, we go over the biological characteristics of the MAPK pathway in colorectal tumors, while illustrating the clinical correlation of RAS and BRAF mutations, particularly its prognostic and predictive value. We also present newly data about recent improvements in the treatment strategy for patients harboring these types of tumors.

EXPERT COMMENTARY

With great advances in the knowledge of molecular basis of RAS and BRAF mutant colorectal cancer in conjunction with biotechnology development and the constant effort for improvement, in the near future many new therapeutic options would be available for the management of this group of patient with dismal prognosis.

The Role of BRAF in Metastatic Colorectal Carcinoma-Past, Present, and Future

With a global incidence of 1.8 million cases, colorectal cancer represents one of the most common cancers worldwide. Despite impressive improvements in treatment efficacy through cytotoxic and biological agents, the cancer-related death burden of metastatic colorectal cancer (mCRC) is still high. mCRC is not a genetically homogenous disease and various mutations influence disease development. Up to 12% of mCRC patients harbor mutations of the signal transduction molecule BRAF, the most prominent being BRAFV600E. In mCRC, BRAFV600E mutation is a well-known negative prognostic factor, and is associated with a dismal prognosis. The currently approved treatments for BRAF-mutated mCRC patients are of little impact, and there is no treatment option superior to others. However, the gradual molecular understanding over the last decades of the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway, resulted in the development of new therapeutic strategies targeting the involved molecules. Recently published and ongoing studies administering a combination of different inhibitors (e.g., BRAF, MEK, and EGFR) showed promising results and represent the new standard of care. In this review, we present, both, the molecular and clinical aspects of BRAF-mutated mCRC patients, and provide an update on the current and future treatment approaches that might direct the therapy of mCRC in a new era.