Changes In Serum CXCL13 Levels Are Associated With Outcomes of Colorectal Cancer Patients Undergoing First-Line Oxaliplatin-Based Treatment

Metastatic colorectal cancer (mCRC) currently lacks reliable biomarkers for precision medicine, particularly for chemotherapy-based treatments. This study examines the behavior of 11 CXC chemokines in the blood of 104 mCRC patients undergoing first-line oxaliplatin-based treatment to pinpoint predictive and prognostic markers. Serum samples were collected before treatment, at response evaluation (EVAR), and at disease progression or last follow-up. Chemokines were assessed in all samples using a Luminex® custom panel. CXCL13 levels increased at EVAR in responders, while in non-responders it decreased. Increasing levels of CXCL13 at EVAR, independently correlated with improved progression-free survival (PFS) and overall survival (OS). Nanostring® analysis in primary tumor samples showed CXCL13 gene expression's positive correlation not only with gene profiles related to an immunogenic tumor microenvironment, increased B cells and T cells (mainly CD8+) but also with extended OS. In silico analysis using RNAseq data from liver metastases treated or not with neoadjuvant oxaliplatin-based combinations, and deconvolution analysis using the MCP-counter algorithm, confirmed CXCL13 gene expression's association with increased immune infiltration, improved OS, and Tertiary Lymphoid Structures (TLSs) gene signatures, especially in neoadjuvant-treated patients. CXCL13 analysis in serum from 36 oxaliplatin-treated patients from the METIMMOX study control arm, reported similar findings. In conclusion, the increase of CXCL13 levels in peripheral blood and its association with the formation of TLSs within the metastatic lesions, emerges as a potential biomarker indicative of the therapeutic efficacy in mCRC patients undergoing oxaliplatin-based treatment.

Epidermal growth factor receptor antagonists in colorectal cancer: emerging strategies for precision therapy

INTRODUCTION

The global prevalence of colorectal cancer highlights the need to enhance treatment strategies for improved patient outcomes. The pivotal role of epidermal growth factor receptor (EGFR) signaling in regulating cellular processes for this disease pinpoints its value as a therapeutic target, despite the emergence of resistance mechanisms over time.

AREAS COVERED

This review discusses the clinical evidence supporting the use of EGFR inhibitors in molecularly-selected patients based on molecular characteristics (notably BRAF V600E and KRAS G12C) including combination approaches targeting different points in in the signaling pathway, as well as strategies such as EGFR inhibitor rechallenge. The role of HER2 inhibitors and emerging approaches such as bispecific antibodies are also reviewed.

EXPERT OPINION

Recently, inhibitors targeting the KRAS G12C variant have emerged, albeit with modest monotherapy activity compared to other tumor types, emphasizing the influence of histologic origins on the EGFR signaling pathway. Integration of EGFR inhibitors into precision medicine has facilitated tailored therapies addressing resistance mechanisms. Patient selection for EGFR inhibitor rechallenge guided by ctDNA findings is crucial, with ongoing investigations exploring novel combinations to enhance EGFR blockade, highlighting the transformative potential of precision medicine in shaping the future of mCRC treatment toward personalized and targeted approaches.

Cetuximab as a Key Partner in Personalized Targeted Therapy for Metastatic Colorectal Cancer

Cetuximab, a chimeric IgG1 monoclonal antibody targeting the epidermal growth factor receptor (EGFR), has revolutionized personalized treatment of metastatic colorectal cancer (mCRC) patients. This review highlights the mechanism of action, characteristics, and optimal indications for cetuximab in mCRC. Cetuximab has emerged as a pivotal partner for novel therapies in specific molecular subgroups, including BRAF V600E, KRAS G12C, and HER2-altered mCRC. Combining cetuximab with immunotherapy and other targeted agents further expands the therapeutic landscape, offering renewed hope for mCRC patients who face the development of resistance to conventional therapies. Ongoing clinical trials have continued to uncover innovative cetuximab-based treatment strategies, promising a brighter future for mCRC patients. This review provides a comprehensive overview of cetuximab's role and its evolving importance in personalized targeted therapy of mCRC patients, offering valuable insights into the evolving landscape of colorectal cancer treatment.

The impact of clinical and translational research on the quality of life during the metastatic colorectal cancer patient journey

The journey of metastatic colorectal cancer patients is complex and challenging, requiring coordination and collaboration between multiple healthcare providers. Understanding patients' needs, fears, feelings, concerns, and behaviors is essential for providing individualized patient-centered care. In recent years, mCRC patients have experienced improvements in clinical outcomes, from 16 months of overall survival to 32 months, thanks to research. However, there is still room for improvement, and integrating clinical and translational research into routine practice can help patients benefit from treatments and techniques that would not be an option. In the Journey of mCRC patients, living well with cancer and quality of life becomes a priority given the outcomes of the disease. Patient reported outcomes (PRO) and Patient Reported Outcome Measures (PROMs) are becoming therefore new estimands in Oncology. Patient advocates represent important figures in this process by prioritizing issues and research questions; evaluating research designs and the performance of the research; the analysis and interpretation of data; and how results are disseminated. Multidisciplinary Tumor Boards and shared decision-making is essential for designing treatment strategies for individual patients. Quality of Life is often prioritized only when it comes to refractory advanced disease and end-of-life care, but it has to be integrated from the beginning, as the emotional impact of diagnosis leads to a vulnerable situation where patients' needs and preferences can be easily overseen. First-line treatment will be chosen among more treatment options than subsequent lines, with longer progression-free survival and a bigger impact on the outcomes. Practicing patient-centered care and optimizing first-line treatment for colorectal cancer patients requires a comprehensive understanding of patient experience and treatment outcomes, which can guide clinical practice and inform regulatory decisions for the benefit of patients.

Immunotherapy for Colorectal Cancer with High Microsatellite Instability: The Ongoing Search for Biomarkers

Microsatellite instability (MSI) is a biological condition associated with inflamed tumors, high tumor mutational burden (TMB), and responses to immune checkpoint inhibitors. In colorectal cancer (CRC), MSI tumors are found in 5% of patients in the metastatic setting and 15% in early-stage disease. Following the impressive clinical activity of immune checkpoint inhibitors in the metastatic setting, associated with deep and long-lasting responses, the development of immune checkpoint inhibitors has expanded to early-stage disease. Several phase II trials have demonstrated a high rate of pathological complete responses, with some patients even spared from surgery. However, in both settings, not all patients respond and some responses are short, emphasizing the importance of the ongoing search for accurate biomarkers. While various biomarkers of response have been evaluated in the context of MSI CRC, including B2M and JAK1/2 mutations, TMB, WNT pathway mutations, and Lynch syndrome, with mixed results, liver metastases have been associated with a lack of activity in such strategies. To improve patient selection and treatment outcomes, further research is required to identify additional biomarkers and refine existing ones. This will allow for the development of personalized treatment approaches and the integration of novel therapeutic strategies for MSI CRC patients with liver metastases.

Unravelling the Complexity of Colorectal Cancer: Heterogeneity, Clonal Evolution, and Clinical Implications

Colorectal cancer (CRC) is a global health concern and a leading cause of death worldwide. The disease's course and response to treatment are significantly influenced by its heterogeneity, both within a single lesion and between primary and metastatic sites. Biomarkers, such as mutations in KRAS, NRAS, and BRAF, provide valuable guidance for treatment decisions in patients with metastatic CRC. While high concordance exists between mutational status in primary and metastatic lesions, some heterogeneity may be present. Circulating tumor DNA (ctDNA) analysis has proven invaluable in identifying genetic heterogeneity and predicting prognosis in RAS-mutated metastatic CRC patients. Tumor heterogeneity can arise from genetic and non-genetic factors, affecting tumor development and response to therapy. To comprehend and address clonal evolution and intratumoral heterogeneity, comprehensive genomic studies employing techniques such as next-generation sequencing and computational analysis are essential. Liquid biopsy, notably through analysis of ctDNA, enables real-time clonal evolution and treatment response monitoring. However, challenges remain in standardizing procedures and accurately characterizing tumor subpopulations. Various models elucidate the origin of CRC heterogeneity, highlighting the intricate molecular pathways involved. This review focuses on intrapatient cancer heterogeneity and genetic clonal evolution in metastatic CRC, with an emphasis on clinical applications.

Treatment of BRAF-V600E mutant metastatic colorectal cancer: new insights and biomarkers

INTRODUCTION

The presence of a BRAF-V600E mutation in metastatic colorectal cancer (mCRC) is observed in approximately 12% of cases and is associated with poor prognosis and aggressive disease. Unlike melanoma, the development of successful BRAF blockade in colorectal cancer has been complex. The phase III BEACON trial made significant progress in the development of BRAF inhibitors by establishing encorafenib-cetuximab as the new standard of care for patients with mCRC who have progressed to one or two previous lines of treatment. Nonetheless, not all patients respond to encorafenib-based combinations, and some responses are short-lived. Identifying new strategies to boost antitumor activity and improve survival is paramount.

AREAS COVERED

The development of targeted therapy for BRAF-V600E mCRC starting with BRAF inhibitors as monotherapy through novel combinations with anti-VEGF or anti-PD1 agents to enhance antitumor activity is reviewed, with a particular focus on the development of predictive and prognostic biomarkers.

EXPERT OPINION

There is a crucial need to better understand tumor biology and develop accurate and reliable biomarkers to enhance the antitumor activity of encorafenib-based combinations. The RNF43 mutation is an accurate and reliable predictive biomarker of response, and combinations that target crosstalk between the MAPK pathway, the immune system, and WNT pathways seem promising.

Impact of the COVID-19 pandemic in the early-onset colorectal cancer

The COVID19 pandemic has affected the spectrum of cancer care worldwide. Early onset colorectal cancer (EOCRC) is defined as diagnosis below the age of 50. Patients with EOCRC faced multiple challenges during the COVID19 pandemic and in some institutions it jeopardized cancer diagnosis and care delivery. Our study aims to identify the clinicopathological features and outcomes of patients with EOCRC in our Centre during the first wave of the pandemic in comparison with the same period in 2019 and 2021.

Patients with EOCRC visited for the first time at Vall d'Hebron University Hospital in Spain from the 1st March to 31st August of 2019, 2020 and 2021 were included in the analysis. 177 patients with EOCRC were visited for the first time between 2019 and 2021, of which 90 patients met the inclusion criteria (2019: 30 patients, 2020: 29 patients, 2021: 31 patients). Neither differences in frequency nor in stage at diagnosis or at first visit during the given periods were observed. Of note, indication of systemic therapy in the adjuvant or metastatic setting was not altered. Days to treatment initiation and enrollment in clinical trials in this subpopulation was not affected due to the COVID-19 outbreak.

Plasmatic BRAF-V600E allele fraction as a prognostic factor in metastatic colorectal cancer treated with BRAF combinatorial treatments

BACKGROUND

Combination of a BRAF inhibitor (BRAFi) and an anti-epidermal growth factor receptor (EGFR), with or without a MEK inhibitor (MEKi), improves survival in BRAF-V600E-mutant metastatic colorectal cancer (mCRC) over standard chemotherapy. However, responses are heterogeneous and there are no available biomarkers to assess patient prognosis or guide doublet- or triplet-based regimens. In order to better characterize the clinical heterogeneity observed, we assessed the prognostic and predictive role of the plasmatic BRAF allele fraction (AF) for these combinations.

PATIENTS AND METHODS

A prospective discovery cohort including 47 BRAF-V600E-mutant patients treated with BRAFi-anti-EGFR ± MEKi in clinical trials and real-world practice was evaluated. Results were validated in an independent multicenter cohort (n= 29). Plasmatic BRAF-V600E AF cut-off at baseline was defined in the discovery cohort with droplet digital PCR (ddPCR). All patients had tissue-confirmed BRAF-V600E mutations.

RESULTS

Patients with high AF have major frequency of liver metastases and more metastatic sites. In the discovery cohort, median progression-free survival (PFS) and overall survival (OS) were 4.4 and 10.1 months, respectively. Patients with high BRAF AF (≥2%, n = 23) showed worse PFS [hazard ratio (HR) 2.97, 95% confidence interval (CI) 1.55-5.69; P = 0.001] and worse OS (HR 3.28, 95% CI 1.58-6.81; P = 0.001) than low-BRAF AF patients (<2%, n = 24). In the multivariable analysis, BRAF AF levels maintained independent significance. In the validation cohort, high BRAF AF was associated with worse PFS (HR 3.83, 95% CI 1.60-9.17; P = 0.002) and a trend toward worse OS was observed (HR 1.86, 95% CI 0.80-4.34; P = 0.15). An exploratory analysis of predictive value showed that high-BRAF AF patients (n = 35) benefited more from triplet therapy than low-BRAF AF patients (n = 41; PFS and OS interaction tests, P < 0.01).

CONCLUSIONS

Plasmatic BRAF AF determined by ddPCR is a reliable surrogate of tumor burden and aggressiveness in BRAF-V600E-mutant mCRC treated with a BRAFi plus an anti-EGFR with or without a MEKi and identifies patients who may benefit from treatment intensification. Our results warrant further validation of plasmatic BRAF AF to refine clinical stratification and guide treatment strategies.

Liver transplantation in metastatic colorectal cancer: are we ready for it?

Colorectal cancer (CRC) is a prevalent disease worldwide, with more than 50% of patients developing metastases to the liver. Five-year overall survival remains modest among patients with metastatic CRC (mCRC) treated with conventional therapies however, liver transplantation in a highly selected population can improve clinical outcomes with an impressive 5-year overall survival of 83%. Despite liver transplantation appearing to be a promising therapeutical option for well-selected patients with mCRC with the liver-limited disease, these data come from small monocentric trials which included a heterogeneous population. Currently, several clinical trials are evaluating liver transplantation in this scenario, aiming for a more accurate patient selection by integrating liquid biopsy, tissue profiling, and nuclear medicine to the already known clinical biomarkers that eventually may lead to a survival improvement. In this paper, the clinical outcomes and inclusion criteria from the most relevant clinical trials and clinical series involving liver transplantation in patients with liver-limited disease colorectal cancer are reviewed as well as the trials currently recruiting.

Establishment of patient-derived tumor organoids to functionally inform treatment decisions in metastatic colorectal cancer

BACKGROUND

Metastatic colorectal cancer (mCRC) patients tend to have modest benefits from molecularly driven therapeutics. Patient-derived tumor organoids (PDTOs) represent an unmatched model to elucidate tumor resistance to therapy, due to their high capacity to resemble tumor characteristics.

MATERIALS AND METHODS

We used viable tumor tissue from two cohorts of patients with mCRC, naïve or refractory to treatment, respectively, for generating PDTOs. The derived models were subjected to a 6-day drug screening assay (DSA) with a comprehensive pipeline of chemotherapy and targeted drugs against almost all the actionable mCRC molecular drivers. For the second cohort DSA data were matched with those from PDTO genotyping.

RESULTS

A total of 40 PDTOs included in the two cohorts were derived from mCRC primary tumors or metastases. The first cohort included 31 PDTOs derived from patients treated in front line. For this cohort, DSA results were matched with patient responses. Moreover, RAS/BRAF mutational status was matched with DSA cetuximab response. Ten out of 12 (83.3%) RAS wild-type PDTOs responded to cetuximab, while all the mutant PDTOs, 8 out of 8 (100%), were resistant. For the second cohort (chemorefractory patients), we used part of tumor tissue for genotyping. Four out of nine DSA/genotyping data resulted applicable in the clinic. Two RAS-mutant mCRC patients have been treated with FOLFOX-bevacizumab and mitomycin-capecitabine in third line, respectively, based on DSA results, obtaining disease control. One patient was treated with nivolumab-second mitochondrial-derived activator of caspases mimetic (phase I trial) due to high tumor mutational burden at genotyping, experiencing stable disease. In one case, the presence of BRCA2 mutation correlated with DSA sensitivity to olaparib; however, the patient could not receive the therapy.

CONCLUSIONS

Using CRC as a model, we have designed and validated a clinically applicable methodology to potentially inform clinical decisions with functional data. Undoubtedly, further larger analyses are needed to improve methodology success rates and propose suitable treatment strategies for mCRC patients.

Sex and gender perspectives in colorectal cancer

Historically women were frequently excluded from clinical trials and drug usage to protect unborn babies from potential harm. As a consequence, the impact of sex and gender on both tumour biology and clinical outcomes has been largely underestimated. Although interrelated and often used interchangeably, sex and gender are not equivalent concepts. Sex is a biological attribute that defines species according to their chromosomal makeup and reproductive organ, while gender refers to a chosen sexual identity. Sex dimorphisms are rarely taken into account, in either preclinical or clinical research, with inadequate analysis of differences in outcomes according to sex or gender still widespread, reflecting a gap in our knowledge for a large proportion of the target population. Underestimation of sex-based differences in study design and analyses has invariably led to 'one-drug' treatment regimens for both males and females. For patients with colorectal cancer (CRC), sex also has an impact on the disease incidence, clinicopathological features, therapeutic outcomes, and tolerability to anticancer treatments. Although the global incidence of CRC is higher in male subjects, the proportion of patients presenting right-sided tumours and BRAF mutations is higher among females. Concerning sex-related differences in treatment efficacy and toxicity, drug dosage does not take into account sex-specific differences in pharmacokinetics. Toxicity associated with fluoropyrimidines, targeted therapies, and immunotherapies has been reported to be more extensive for females with CRC than for males, although evidence about differences in efficacy is more controversial. This article aims to provide an overview of the research achieved so far into sex and gender differences in cancer and summarize the growing body of literature illustrating the sex and gender perspective in CRC and their impact in relation to tumour biology and treatment efficacy and toxicity. We propose endorsing research on how biological sex and gender influence CRC as an added value for precision oncology.

Advances in immune checkpoint inhibitor combination strategies for microsatellite stable colorectal cancer

Immune checkpoint inhibitors have reshaped the prognostic of several tumor types, including metastatic colorectal tumors with microsatellite instability (MSI). However, 90-95% of metastatic colorectal tumors are microsatellite stable (MSS) in which immunotherapy has failed to demonstrate meaningful clinical results. MSS colorectal tumors are considered immune-cold tumors. Several factors have been proposed to account for this lack of response to immune checkpoint blockade including low levels of tumor infiltrating lymphocytes, low tumor mutational burden, a high rate of WNT/β-catenin pathway mutations, and liver metastases which have been associated with immunosuppression. However, studies with novel combinations based on immune checkpoint inhibitors are showing promising activity in MSS colorectal cancer. Here, we review the underlying biological facts that preclude immunotherapy activity, and detail the different immune checkpoint inhibitor combinations evaluated, along with novel immune-based therapies, to overcome innate mechanisms of resistance in MSS colorectal cancer.

Identification and external validation of clinical-molecular features to predict benefit from oxaliplatin reintroduction/rechallenge in patients with refractory metastatic colorectal cancer (mCRC)

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Background: Oxaliplatin is a backbone cytotoxic treatment for mCRC patients, particularly in the front-line setting. In the refractory disease, current treatment options are scarce and with limited efficacy. Several retrospective studies have explored the efficacy of oxaliplatin reintroduction/rechallenge (OxRe) in this scenario. However, more evidence is still needed to determine which patients do benefit from this treatment strategy. Methods: The discovery cohort includes all patients treated with oxaliplatin in a third- or fourth-line setting at VHIO between 2015 and 2021 (N = 102). Results were externally validated in a real-world cohort of patients treated at community oncology practices from Oncoclínicas Group in Brazil (N = 157). We analyzed the impact of clinical-molecular features in uni- and multivariable prognostic models in terms of median progression free survival (mPFS) (discovery cohort) and median time to treatment discontinuation (mTTD) (validation cohort). For both cohorts separately, data was extracted from EHRs in structured formats (demographics, tumor characteristics, pharmacy records) and combined with elements from unstructured sources (physician notes on progression and survival status) using technology-based abstraction techniques. Results: In the discovery cohort, 102 out of 735 mCRC patients (13,9%) were eligible. Median oxaliplatin-free interval (from Oxl stop to OxRe) was 17 months (CI95% 13.0-23.2). In OxRe setting, mPFS was 4.0 months (CI95% 3.29-5.03). In PFS multivariate analysis, determinants of favorable outcome were left tumor location (p = 0.01), oxaliplatin-free interval (p = 0.03), administration of Bev in refractory setting (p = 0.001), and not receiving Bev in first-line treatment (p = 0.008). Overall, 27% of all patients had a mPFS > 6 months with OxRe. In the validation cohort, out of 4,317 patients with mCRC, 157 (4%) were treated with OxRe. Median oxaliplatin-free interval was 15 months. Median time to treatment discontinuation (mTTD) of the OxRe was 3.4 months (CI95% 2.8-4.2). In multivariable model, the only independent prognostic factor was addition of Bev to OxRe (p = 0.036). Interestingly, 31% of all patients had mTTD > 6 months, largely enriched (65%) in patients with first Bev exposure at the time of OxRe. Conclusions: This study suggests that in refractory mCRC patients re-exposed to oxaliplatin-based chemotherapy, the addition of Bev is associated with improved outcomes. One-third of the patients are long-term responders (PFS/TTD > 6 months), reinforcing the value of this strategy in selected populations and the relevance of anti-angiogenic agents in refractory mCRC.

A Comprehensive Biomarker Analysis of Microsatellite Unstable/Mismatch Repair Deficient Colorectal Cancer Cohort Treated with Immunotherapy

The search for immunotherapy biomarkers in Microsatellite Instability High/Deficient Mismatch Repair system (MSI-H/dMMR) metastatic colorectal cancer (mCRC) is an unmet need. Sixteen patients with mCRC and MSI-H/dMMR (determined by either immunohistochemistry or polymerase chain reaction) treated with PD-1/PD-L1 inhibitors at our institution were included. According to whether the progression-free survival with PD-1/PD-L1 inhibitors was longer than 6 months or shorter, patients were clustered into the IT-responder group (n: 9 patients) or IT-resistant group (n: 7 patients), respectively. In order to evaluate determinants of benefit with PD-1/PD-L1 inhibitors, we performed multimodal analysis including genomics (through NGS panel tumour-only with 431 genes) and the immune microenvironment (using CD3, CD8, FOXP3 and PD-L1 antibodies). The following mutations were more frequent in IT-resistant compared with IT-responder groups: B2M (4/7 versus 2/9), CTNNB1 (2/7 versus 0/9), and biallelic PTEN (3/7 versus 1/9). Biallelic ARID1A mutations were found exclusively in the IT-responder group (4/9 patients). Tumour mutational burden did not correlate with immunotherapy benefit, neither the rate of indels in homopolymeric regions. Of note, biallelic ARID1A mutated tumours had the highest immune infiltration and PD-L1 scores, contrary to tumours with CTNNB1 mutation. Immune microenvironment analysis showed higher densities of different T cell subpopulations and PD-L1 expression in IT-responders. Misdiagnosis of MSI-H/dMMR inferred by discordances between immunohistochemistry and polymerase chain reaction was only found in the IT-resistant population (3/7 patients). Biallelic ARID1A mutations and Wnt signalling activation through CTNNB1 mutation were associated with high and low T cell immune infiltrates, respectively, and deserve special attention as determinants of response to PD-1/PD-L1 inhibitors. The non-MSI-H phenotype in dMMR is associated with poor benefit to immunotherapy. Our results suggest that mechanisms of resistance to immunotherapy are multi-factorial.

Pharmacokinetics and pharmacodynamics of approved monoclonal antibody therapy for colorectal cancer

INTRODUCTION

The introduction of monoclonal antibodies to the chemotherapy backbone treatment has challenged the paradigm of metastatic colorectal cancer (mCRC) treatment. Their mechanism of action and pharmacokinetics are complex but important to understand in order to improve patient selection and treatment outcomes for mCRC population.

AREAS COVERED

This review examines the scientific data, pharmacodynamics, and pharmacokinetics of approved monoclonal antibodies used to treat mCRC patients, including agents targeting signaling via VEGFR (bevacizumab and ramucirumab), EGFR (cetuximab and panitumumab), HER2/3 target therapy, and immunotherapy agents such as pembrolizumab or nivolumab. Efficacy and mechanism of action of bispecific antibodies are also covered.

EXPERT OPINION

mCRC is a heterogeneous disease and the optimal selection and sequence of treatments is challenging. Monoclonal antibodies have complex pharmacokinetics and pharmacodynamics, with important interactions between them. The arrival of bioequivalent molecules to the market increases the need for the characterization of pharmacokinetics and pharmacodynamics of classic monoclonal antibodies to reach bioequivalent novel molecules.

Encorafenib plus cetuximab for the treatment of BRAF-V600E-mutated metastatic colorectal cancer

B-type RAF (BRAF)-V600E mutations in metastatic colorectal cancer (mCRC) have been described in up to 12% of the patients. This mutation confers a bad prognostic and poor response with standard chemotherapy. Unlike the scenario for BRAF mutant melanoma, successful BRAF blockade in mCRC has emerged as a complex path, primarily due to the complex underlying biology of mCRC. The BEACON trial has reshaped the therapeutic landscape of BRAF mCRC demonstrating the benefit of the BRAF inhibitor encorafenib in combination with the anti-epidermal growth factor receptor cetuximab. This paper aims to review the main features of BRAF mCRC as well as to review the development of targeted therapy and biomarkers in this specific population. Finally, a deep insight into the underlying biology and molecular classification of BRAF-V600E mCRC has also been performed. The words 'BRAF-V600E mutation', 'colorectal cancer', 'BRAF inhibitors', 'consensus molecular subtypes', 'encorafenib', and 'cetuximab' were used to identify the clinical trials from phase I to phase III related to the development of BRAF inhibitors in this population. A deep search among international meetings (American Society of Clinical Oncology and European Society of Medical Oncology) has been performed to incorporate the last trials presented. BRAF-V600E mCRC is a challenging disease, mostly because of its molecular biology. The BEACON trial has been the most important therapeutic change in the last decade. Nevertheless, new information regarding biomarkers or novel combinations including BRAF inhibitors plus immune checkpoint inhibitors are also promising.

Abstract 3489: Luminex-based analysis of serum CXC chemokines showing their usefulness as prognostic and/or predictive biomarkers in metastatic colorectal cancer patients

Introduction: CXC chemokines are a family of small, secreted, chemotactic molecules acting through the binding to their corresponding CXC receptors (CXCRs) and stimulating the migration of cells, most notably those of the immune system. They have been associated with both pro-tumor and anti-tumor activity. Previously, we reported increased expression and secretion levels of CXCL1, 2 and 8 in oxaliplatin (OXA)-resistant colorectal cancer (CRC) cell lines. The aim of this study is to evaluate the usefulness of measuring the serum levels of a CXC chemokine panel in CRC patients as prognostic and/or predictive biomarkers of first-line treatment.

Material and Methods: In this multicenter study sera from advanced CRC patients to be treated with OXA-based schedules were collected at three different time points between November 2016 and June 2021: before treatment (PRET), at first response evaluation (EVAR) and at the time of progression/end of study (PROG). Levels of CXCL1, 2, 5, 6, 8, 9, 10, 11, 12, 13, 16 chemokines were analyzed using a custom Bio-plex Pro Human assay (Bio-Rad, USA) in a Luminex® 200 equipment. Comparisons of chemokines’ levels between Responders (R) and Non-Responders (NR) at different time-points were carried out using the Mann Whitney U and Wilcoxon tests. Log Rank and Cox regression were used to study differences in progression-free (PFS) and overall survival (OS); Chi-square or Fisher’s tests were used to study associations between categorical variables. All differences were considered statistically significant when p values ≤ 0.05.

Results: A total of 107 patients were enrolled in this study: 72% male; median age 66 years old; metastasis: 78% liver, 41% lung; mutations: 44% KRAS, 4% BRAF; treatments: FOLFOX/XELOX = 30%/4% plus Bevacizumab/anti-EGFR = 36%/24%; 64% responders (complete response + partial response); 13% stable disease; 11% progressors. All chemokines could be detected in the samples. Levels below median (LBM) of CXCL1, 8, 11 and 13 correlated with better OS (HR=0.55 p=0.02; HR=0.47 p=0.005; HR=0.6 p=0.05; HR=0.54 p=0.02, respectively). LBM of CXCL16 correlated with better OS and PFS (HR=0.6 p=0.04; HR=0.6 p=0.005) and of CXCL5 with better PFS (HR 0.6 p 0.011); mean CXCL9 levels were lower in responders’ PRET samples (p=0.03) and LBM correlated with better OS (HR=0.5 p=0.019). In responders, all chemokines except CXCL10, 13 and 16 presented decreased levels at EVAR vs. PRET. Moreover, CXCL1, 2, 5, 8, 11 and 16 levels increased at PROG vs. EVAR. In non-responders, non-conclusive results were found.

Conclusion: our results show that serum levels of specific CXC chemokines may be used as prognostic/predictive markers in metastatic CRC. Further analysis will be performed, and an update of this study will be presented in the AACR meeting.

Citation Format: Sara Cabrero-de las Heras, Ferran Losa, Xavier Hernández-Yagüe, Gemma Soler, Cristina Bugés, Iosune Baraibar, Andrea Plaja, Eduard Teixidor, Eva Martínez-Balibrea. Luminex-based analysis of serum CXC chemokines showing their usefulness as prognostic and/or predictive biomarkers in metastatic colorectal cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3489.

Molecular characterization and subsequent treatments after encorafenib-cetuximab +/- binimetinib in BRAF V600E-mutated colorectal cancer

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Background: The BRAF-V600E mutation confers poor prognosis in patients with mCRC. E-C+/-B improve clinical outcomes compared with standard of care. Data about subsequent treatment lines and the impact of NGS in the treatment choice after the BRAF targeted treatment are still limited. We have analyzed the global overall survival (OS) and the impact of NGS to guide subsequent treatments (approved targeted therapies (TT) or clinical trials (CT)) after E-C+/-B. Methods: Patients who had received E-C+/-B were included. Clinical data was collected prospectively. Tissue NGS was performed prospectively and retrospectively using an in-house NGS panel (VHIO-300). Subsequent treatments’ clinical outcomes were described. Percentage of patients who received TT or CT based on NGS results is reported. Clinical outcomes were calculated using survival Kaplan-Meier curves. Results: From 2017 to 2021, 59 patients with refractory mCRC received E-C+/-B at our institution. 50 patients have already progressed to the BRAF inhibitor combination and 9 patients remain on BRAF inhibitor treatment. Tumor tissue for NGS testing before BRAF inhibitor treatment was available in 70% of patients (41/59). BRAF-V600E mutation was confirmed in tissue using ddPCR in all patients. The most frequent alterations were: BRAF-V600E 93%, TP53 64%, RNF43 30%, APC 20%, PIK3CA 14%, NOTCH1/2 9%, RANBP2 8%, PTEN 8%, MET amplification 5%. MSI incidence was 10%, 2 out of 6 (33%) received subsequent immunotherapy. After the BRAF inhibitor combination, 23 patients (38%) did not receive subsequent treatment (clinical deterioration or death). The 27 remaining patients (62%) received 41 subsequent treatments (37% of them were TT or CT). Median subsequent lines after the BRAF inhibitor combination were 1 (0-3). NGS led to targeted therapy in 20% of the patients: BRAF inhibitors combos (20%), microtubule inhibitors (13%), antiPD1 (13%), NOTCH inhibitors (6%), and MET inhibitor (6%). ORR among patients who received matched TT or CT was 6% and DCR (CR+PR+SD) was 47%. The median OS after the BRAF inhibitor was 3.8 months; 10.1 months vs 3.0 months (HR 0.43 (95%CI 0.2-0.95), p = 0.04) for those patients who received TT or CT vs patients who did not receive TT or CT. When MSI patients were excluded mOS was 5.2 vs 3.0 months (HR 0.61 (95%CI 0.27-1.37), p = 0.23) respectively. There were no differences in terms of OS regarding the number of previous lines (0-1 vs 2-3, HR 0.75 (95%CI 0.4-1.42), p = 0.37) or with the BRAF inhibitor regimen used (E-C vs E-C-B) (HR 0.84, (95%CI 0.44-1.6), p = 0.61) Conclusions: This study suggests that patients with BRAF-V600E mutant mCRC could have benefit when treated with TT and/or in CT after a BRAF inhibitor-based therapy, including immunotherapy. Genomic analysis might help to guide subsequent treatments. Because of molecular heterogeneity, these patients should be discussed in Molecular Tumor Boards.

Impact of circulating tumor DNA (ctDNA) mutant allele fraction in response to anti-angiogenic therapy in RAS-mutant metastatic colorectal cancer (mCRC): Clinical data in the first-line setting and correlation in patient-derived xenograft (PDX) models

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Background: Currently, there are no well-established biomarkers available to select mCRC patients (pts) who will benefit most from antiangiogenic therapy. RAS mutant (mt) allele fraction in plasma (plMAF) is an independent prognostic factor in mCRC. Preliminary data from our group suggests the possible predictive role of plMAF in RAS mt pts treated with 1st line chemotherapy (ct) +/- bevacizumab (bev). Methods: Data prospectively/retrospectively collected from RASmt mCRC pts who received 1st line ct+/-bev treatment in our center, selecting the subset of pts with plMAF sample evaluable with digital PCR (BEAMing) at baseline. Pts were stratified as high (≥ 5.8%) or low ( < 5.8%) plMAF, based on a previously established prognostic cutoff (Elez et al, Mol Onc 2019). We investigated the associations between clinic-pathological variables, overall survival (OS), and progression-free survival (PFS) stratified by plMAF RAS levels using Cox regression models. OS and PFS were calculated by Kaplan-Meier method. Murine PDX were developed from mCRC pts including models from patients with KRASG12/G13 mutations to explore recapitulation of the clinical findings. Results: From October ‘17 to December ‘21, 102 basal plasma samples were analyzed by BEAMing. 47 pts (46%) were classified as high, 39 pts (38%) as low, and 16 (16%) as no-mt detected by BEAMing (non-shedding). OS was significant longer in low plMAF pts than in high plMAF pts (median OS 15.9 vs 37.1 months (mo); HR 0.43; p = 0.001). In high plMAF pts, a trend towards a better PFS was observed in those pts treated with ct+bev compared to ct alone (median 9.4 vs 6.1 mo; HR 0.6; p = 0.18). No differences were observed in low plMAF pts treated with ct +/- bev (median 14.5 vs 14.9 mo; HR 1.2; p = 0.58). Results were not modified when adjusted by the presence of liver metastases. The multivariate PFS model showed no association between RAS plMAF and clinicopathological variables, except for treatment benefit with ct+bev and better outcomes in pts with resectable liver metastases. Interestingly, human ctDNA in one murine PDX model from non-shedding pt was not detectable, whereas human ctDNA was present in another PDX model with a plMAF of 36.2%. Conclusions: This study suggests that plMAF could be a promising predictive biomarker of response to bev in 1st line RASmt mCRC, but more pts need to be analyzed to confirm this effect. Our results confirm the prognostic role of RASmt plMAF in mCRC. plMAF could partially depend on tumor cell shedding degree and characteristics on the tumor vasculature architecture, this is being investigated in ongoing imaging studies and PDX models. These models will also help to understand the biology behind tumor response to bev and its connection with ctDNA shedding.

Ongoing and evolving clinical trials enhancing future colorectal cancer treatment strategies

INTRODUCTION

Molecular profiling has led to significantly longer survival in metastatic colorectal cancer (CRC) patients. Clinical guidelines recommend testing for KRAS/NRAS, BRAF and MSI status and over the last few years several promising new biomarkers have also been identified. Circulating tumor DNA has reshaped the prognosis of localized CRC. These genomic findings can guide treatment management to improve clinical outcomes.

AREAS COVERED

Preclinical and clinical data over the last decade were reviewed for known and novel biomarkers with clinical implications in refractory and metastatic CRC. In the localized stage, al clinical trials involving new approaches such as liquid biopsy or neoadjuvant immunotherapy are also discussed. Molecular alterations and targeted agents are described, and data from completed and ongoing studies with targeted therapy and immunotherapies are presented.

EXPERT OPINION

The implementation of liquid biopsies in the localized CRC setting has reshaped management of this disease. The expanded use of biomarkers to guide the treatment of patients with CRC has revealed a level of complexity arising from interactions between different biomarkers. Prevalence of most established targetable biomarkers is low, however the number of identified biomarkers in CRC is increasing. Thus, metastatic CRC may ultimately be considered an umbrella diagnosis encompassing numerous rare disease subtypes.

Combined Treatment with Immunotherapy-Based Strategies for MSS Metastatic Colorectal Cancer

In recent years, deepening knowledge of the complex interactions between the immune system and cancer cells has led to the advent of effective immunotherapies that have revolutionized the therapeutic paradigm of several cancer types. However, colorectal cancer (CRC) is one of the tumor types in which immunotherapy has proven less effective. While there is solid clinical evidence for the therapeutic role of immune checkpoint inhibitors in mismatch repair-deficient (dMMR) and in highly microsatellite instable (MSI-H) metastatic CRC (mCRC), blockade of CTLA-4 or PD-L1/PD-1 as monotherapy has not conferred any major clinical benefit to patients with MMR-proficient (pMMR) or microsatellite stable (MSS) mCRC, reflecting 95% of the CRC population. There thus remains a high unmet medical need for the development of novel immunotherapy approaches for the vast majority of patients with pMMR or MSS/MSI-low (MSI-L) mCRC. Defining the molecular mechanisms for immunogenicity in mCRC and mediating immune resistance in MSS mCRC is needed to develop predictive biomarkers and effective therapeutic combination strategies. Here we review available clinical data from combinatorial therapeutic approaches using immunotherapy-based strategies for MSS mCRC.

The Evolving Role of Consensus Molecular Subtypes: a Step Beyond Inpatient Selection for Treatment of Colorectal Cancer

OPINION STATEMENT

The heterogenous nature of colorectal cancer (CRC) renders it a major clinical challenge. Increasing genomic understanding of CRC has improved our knowledge of this heterogeneity and the main cancer drivers, with significant improvements in clinical outcomes. Comprehensive molecular characterization has allowed clinicians a more precise range of treatment options based on biomarker selection. Furthermore, this deep molecular understanding likely extends therapeutic options to a larger number of patients. The biological associations of consensus molecular subtypes (CMS) with clinical outcomes in localized CRC have been validated in retrospective clinical trials. The prognostic role of CMS has also been confirmed in the metastatic setting, with CMS2 having the best prognosis, whereas CMS1 tumors are associated with a higher risk of progression and death after chemotherapy. Similarly, according to mesenchymal features and immunosuppressive molecules, CMS1 responds to immunotherapy, whereas CMS4 has a poorer prognosis, suggesting that a CMS1 signature could identify patients who may benefit from immune checkpoint inhibitors regardless of microsatellite instability (MSI) status. The main goal of these comprehensive analyses is to switch from "one marker-one drug" to "multi-marker drug combinations" allowing oncologists to give "the right drug to the right patient." Despite the revealing data from transcriptomic analyses, the high rate of intra-tumoral heterogeneity across the different CMS subgroups limits its incorporation as a predictive biomarker. In clinical practice, when feasible, comprehensive genomic tests should be performed to identify potentially targetable alterations, particularly in RAS/BRAF wild-type, MSI, and right-sided tumors. Furthermore, CMS has not only been associated with clinical outcomes and specific tumor and patient phenotypes but also with specific microbiome patterns. Future steps will include the integration of clinical features, genomics, transcriptomics, and microbiota to select the most accurate biomarkers to identify optimal treatments, improving individual clinical outcomes. In summary, CMS is context specific, identifies a level of heterogeneity beyond standard genomic biomarkers, and offers a means of maximizing personalized therapy.