BRAF-mutant Colorectal Cancer Research Articles

Plasma Concentrations of Gut Hormones Acyl Ghrelin and Peptide YY and Subsequent Risk of Colorectal Cancer and Molecular Tumor Subtypes.

The findings of this study do not support a major role for the metabolic gut hormones ghrelin and PYY in colorectal cancer development but suggest the possibility of an involvement for ghrelin in specific tumor subtypes. Elucidating subtype-specific risk factors and mechanisms of carcinogenesis may have implications for precision prevention.

Economic evaluation of encorafenib with cetuximab in patients with BRAF V600E-mutant metastatic colorectal cancer in France: a cost-effectiveness analysis using data from the BEACON CRC randomised controlled trial

ObjectiveThe BEACON CRC randomised controlled trial (NCT02928224) in BRAF-mutant metastatic colorectal cancer (mCRC) patients showed improved overall survival for the combination treatment of encorafenib (BRAF inhibitor) with cetuximab (EGFR inhibitor)...

Sensitivities and Dependencies of BRAF Mutant Colorectal Cancer Cell Lines with or without PIK3CA Mutations for Discovery of Vulnerabilities with Therapeutic Potential.

Background: Colorectal cancer represents a common malignancy and remains incurable in the metastatic stage. Identification of molecular alterations that are present in colorectal cancer has led to the introduction of targeted therapies that improve outcomes. BRAF and PIK3CA mutations are observed in a subset of colorectal cancers. Colorectal cancers bearing BRAF mutations may be treated with specific BRAF inhibitors. These drugs benefit patients with BRAF mutant colorectal cancers but responses are rather brief, and progression is the rule. In contrast, no PI3K inhibitors have proven successful yet in the disease. Thus, new treatments to supplement the currently available drugs would be welcome to further improve survival. Methods: Profiled colorectal cancer cell lines from the Cancer Cell Line Encyclopedia (CCLE) were examined for BRAF and PIK3CA mutations and were interrogated for molecular characteristics and concomitant alterations that mirror clinical sample alterations. The Genomics of Drug Sensitivity in Cancer (GDSC) project was used for determination of drug sensitivities of BRAF mutated colorectal cell lines with or without concomitant PIK3CA mutations. The Cancer Dependency Map project served as the basis for identification of molecular dependencies and vulnerabilities in these cell lines. Results: CCLE includes 84 colorectal cancer cell lines, which recapitulate the molecular landscape of colorectal cancer. Of these, 23 and 24 cell lines possess BRAF and PIK3CA mutations, respectively. Seven BRAF mutant cell lines have V600E mutations and 14 PIK3CA mutant cell lines have hotspot helical or kinase domain mutations. V600E BRAF mutant cell lines with or without hotspot PIK3CA mutations are heterogeneous in their MSI status and mimic colorectal cancer tissues in other prevalent abnormalities including APC and TP53 mutations. Essential genes for survival include CTNNB1, WRN, and pyrimidine metabolism enzyme CAD. Besides BRAF mutations, BRAF inhibitor sensitivity in colorectal cancer cell lines is conferred by SACS mutations and PRKN locus loss. Conclusions: Colorectal cancer cell lines bearing the frequent BRAF and PIK3CA mutations present many alterations of the parental cancer tissue. Described vulnerabilities represent leads for therapeutic exploration in colorectal cancers with the corresponding alterations.

Response to BRAF-targeted Therapy Is Enhanced by Cotargeting VEGFRs or WNT/β-Catenin Signaling in BRAF-mutant Colorectal Cancer Models.

The fact that 10% of colorectal cancer tumors harbor BRAF V600E mutations suggested targeting BRAF as a potential therapy. However, BRAF inhibitors have only limited single-agent efficacy in this context. The potential for combination therapy has been shown by the BEACON trial where targeting the EGF receptor with cetuximab greatly increased efficacy of BRAF inhibitors in BRAF-mutant colorectal cancer. Therefore, we explored whether efficacy of the mutant BRAF inhibitor vemurafenib could be enhanced by cotargeting of either oncogenic WNT/β-catenin signaling or VEGFR signaling. We find the WNT/β-catenin inhibitors pyrvinium, ICG-001 and PKF118-310 attenuate growth of colorectal cancer cell lines in vitro with BRAF-mutant lines being relatively more sensitive. Pyrvinium combined with vemurafenib additively or synergistically attenuated growth of colorectal cancer cell lines in vitro. The selective and potent VEGFR inhibitor axitinib was most effective against BRAF-mutant colorectal cancer cell lines in vitro, but the addition of vemurafenib did not significantly increase these effects. When tested in vivo in animal tumor models, both pyrvinium and axitinib were able to significantly increase the ability of vemurafenib to attenuate tumor growth in xenografts of BRAF-mutant colorectal cancer cells. The magnitude of these effects was comparable with that induced by a combination of vemurafenib and cetuximab. This was associated with additive effects on release from tumor cells and tumor microenvironment cell types of substances that would normally aid tumor progression. Taken together, these preclinical data indicate that the efficacy of BRAF inhibitor therapy in colorectal cancer could be increased by cotargeting either WNT/β-catenin or VEGFRs with small-molecule inhibitors.

Surgical Resection for Local and Lateral Lymph Node Recurrence of MSI-high Cecal Cancer with the BRAF V600E Mutation.

An 84-year-old female underwent open right hemicolectomy with D3 lymph node dissection for cecal cancer, pathologically identified as pT4aN2M0 Stage IIIc and BRAF mutation-positive. Due to early recurrence of abdominal wall and right lateral lymph nodes, the patient was treated with FOLFOXIRI+Bevacizumab. Imaging after 5 courses of chemotherapy found tumor shrinkage and no new metastases. The patient did not tolerate chemotherapy well, and tumor resection was performed. Microsatellite instability (MSI) testing using multiplex polymerase chain reaction (PCR) fragment analysis revealed MSI-high status. The patient is currently recurrence-free without chemotherapy at 1 year postoperatively. BRAF-mutated colorectal cancer has a poor prognosis, and may require resection of the metastatic or recurrent tumor after comprehensive evaluation.

26P NOTCH1 driven metastasis in BRAF mutated colorectal cancer

10% of colorectal cancers (CRC) will have a BRAF mutation (BM). This represents a poor prognostic group. We have developed a novel, metastatic genetically engineered mouse model (GEMM) of BM CRC and derived a prognostic RNA signature.

Tumor Antigenicity and a Pre-Existing Adaptive Immune Response in Advanced BRAF Mutant Colorectal Cancers.

Simple SummaryBRAF mutant metastatic CRCs (BRAF-mCRCs) are considered a unique clinical entity characterized by a dismal prognosis and that do not respond efficiently to both standard chemotherapy and to orally selective inhibitors of BRAFV600E. In this study, the gene expression profiles of 89 immunotherapy-naïve BRAF-CRCs were generated using the PanCancer IO 360 gene expression panel to improve the knowledge of the mechanisms involved in tumor-suppressive immune functions in BRAF-mCRCs. A significant fraction of BRAF-mCRCs shows a hot/inflamed profile and may be potential candidates for responding to immunotherapy. Only a partial overlap between these hot signatures and the presence of microsatellite instability (MSI) was observed, demonstrating that MSI tumors showed a not differential expression of MHC Class I antigen presentation pathway compared with microsatellite-stable tumors. The analysis of gene expression profiles is a promising strategy both for immune profiling of primary tumors before any treatment and for following the evolution of metastatic disease during therapy.The main hypothesis of this study is that gene expression profiles (GEPs) integrating both tumor antigenicity and a pre-existing adaptive immune response can be used to generate distinct immune-related signatures of BRAF mutant colorectal cancers (BRAF-CRCs) to identify actionable biomarkers predicting response to immunotherapy. GEPs of 89 immunotherapy-naïve BRAF-CRCs were generated using the Pan-Cancer IO 360 gene expression panel and the NanoString nCounter platform and were correlated with microsatellite instability (MSI) status and with CD8+ tumor-infiltrating lymphocyte (TIL) content. Hot/inflamed profiles were found in 52% of all cases, and high scores of Tumor Inflammation Signature were observed in 42% of the metastatic BRAF-CRCs. A subset of MSI tumors showed a cold profile. Antigen Processing Machinery (APM) signature was not differentially expressed in MSI tumors compared with MSS cases. By contrast, the APM signature was significantly upregulated in CD8+ BRAF-CRCs versus CD8− tumors. Our study demonstrates that a significant fraction of BRAF-CRCs may be a candidate for immunotherapy and that the simultaneous analysis of MSI status and CD8+ TIL content increases accuracy in identifying patients who can potentially benefit from immune checkpoint inhibitors. GEPs may be very useful in expanding the spectrum of patients with BRAF-CRCs who can benefit from immune checkpoint blockade.

Molecular genetic characteristics of colorectal cancer depending on the status of microsatellite instability

Introduction. The emergence of new markers that determine the choice of therapy for metastatic colorectal cancer (CRC) has led to an increase in overall survival. The optimal treatment tactics now take into account both clinical and molecular-genetic characteristics of the tumor.Aim. Investigation of the features of the KRAS, NRAS and BRAF mutations and amplification of the HER2 gene depending on microsatellite instability (MSI) in CRC.Materials and methods. The study included 400 patients with CRC. MSI, BRAF V600E mutation, mutations in the KRAS and NRAS genes was identified to them. MSI was determined by fragment analysis, and mutations in the KRAS, NRAS, BRAF genes by realtime PCR. HER2 amplification was determined in 100 patients with a negative RAS/BRAF. NTRK translocations were determined in all patients with MSI. Data on preoperative levels of CEA and CA19-9 were obtained from 185 patients.Results and discussion. The prevalence of MSI was 6.8%. The prevalence of KRAS, NRAS, BRAF mutations in CRC with MSI was 66.7%, and in CRC with MSS - 52.3%. In patients with MSI, the level of CEA was lower than in MSS (p = 0.0061). The overall prevalence of KRAS and NRAS mutations was 45% and 2.5%. The overall prevalence of the BRAF V600E mutation was 5.8% and was more common in MSI-positive tumors (p < 0.0001). Regardless of MSI, BRAF-positive tumors were characterized by right-sided localization (p < 0.0001), category T3-4 (p = 0.013), lymph node involvement (p = 0.004), carcinomatosis (p = 0.046), high levels of CA19-9 (p = 0.014). HER2 amplification was found in 7% of wild-type RAS/BRAF cases and was associated with rectal cancer (p = 0.044), category T3-4 (p = 0.041), and distant metastases (p = 0.038). HER2 amplifications and NTRK translocations were not detected in cases with MSI.Conclusion. MSI-positive CRC had a higher prevalence of mutations in major genes. CRC with the BRAF V600E mutation and HER2 amplification had aggressive clinical and morphological parameters.

Abstract LB204: Theclass Iselective, oral HDAC inhibitor OKI-179 increases tumor regressions when combined with the MEK inhibitor binimetinib inmodels of NRAS melanoma

Abstract Activating RAS pathway mutations are found in >30% of human tumors, and often associated with poor outcomes. While RAS-pathway targeted drugs have been approved, their activity as single-agents remains modest, supporting the need for rational targeted combinations to improve patient outcomes. Multiple studies have proposed a chemical synthetic lethality between Class I histone deacetylase inhibitors (HDACi), and RAS-pathway inhibitors in RAS-pathway mutated models. This synthetic lethality occurs due to a combined effect to inhibit double-stranded (ds) DNA repair and other survival pathways to drive apoptosis and tumor regressions. The use of HDACi in solid tumors and combinations has been challenged by poor potency, selectivity, safety and convenience, highlighting the need for a better HDACi in the clinic. OKI-179, a novel largazole derivative, is a potent, Class I-selective, oral HDACi that has completed Ph 1 clinical trials in patients with solid tumors. The clinical profile shows the potential to achieve exposure consistent with preclinical activity with strong pharmacodynamic activity at tolerated doses, supporting the development of OKI-179 in solid tumor combinations. Here we show synergistic activity of combining OKI-179 with the MEK inhibitor binimetinib (bini) or bini + RAF-inhibitor encorafenib (enco/bini) in both CDX and PDX models of NRAS-mutated melanoma and BRAF-mutated colorectal cancer (CRC). In vitro, combining OKI-179 with bini in SKMEL-2 NRASMT melanoma cells shows strong synergy, inducing a significant increase in cell death compared to single agents at clinically achievable drug concentrations. This activity was associated with a significant increase in gH2AX, a marker of ds DNA breaks, and apoptosis as measured by cleaved PARP. The activity of this combination was further investigated in vivo in established PDx models of NRAS-mutant melanoma, MEL278 and MM415. As single agents, both bini (3.5 mg/kg PO bid,21 d) and OKI-179 (80 mg/kg PO; 5/wk x 3 wk), doses that mimic the clinical exposure of these molecules, showed modest tumor growth inhibition (TGI). Combining bini and OKI-179 induced significantly greater TGI, including regression in 28-50% of the tumors, as compared to 0-6% for bini alone. A similar outcome was also observed in HT29 tumors (BRAFmt CRC) where the combination of OKI-179 and enco/bini showed regression in 50% of tumors, compared to 0% for OKI-179 or enco/bini alone. This supports the potential for additive efficacy of HDACi combined with RAS-pathway inhibitors across RAS-pathway mutations and tumor types. No additivity was observed in only one model (CRC563 - BRAFmt). These data show the potential for OKI-179 to synergize with RAS-pathway inhibitors across multiple indications. To investigate, a Phase1b/2 trial of OKI-179 with binimetinib in NRAS melanoma will initiate in early 2022. Citation Format: Richard Woessner, Patrice Lee, Eric Brown, Duncan H. Walker, James Winkler, Tony Piscopio. Theclass Iselective, oral HDAC inhibitor OKI-179 increases tumor regressions when combined with the MEK inhibitor binimetinib inmodels of NRAS melanoma [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 LB204.

Abstract 338: Anti-EGF antibodies significantly improve the activity of BRAF and KRAS inhibitors in preclinical models

Abstract Background: The EGF/EGFR pathway is involved in the emergence of resistance to BRAF and MEK inhibitors and the combination of encorafenib with the anti-EGFR antibody cetuximab has been recently approved in BRAF-positive, advanced colorectal cancer (CRC). Vaccination against EGF represents an alternative to the administration of monoclonal antibodies against EGFR 1-2. In this study, we tested if antibodies generated by vaccination with IN01 (biologic fusion molecule), could improve the antitumor activity of encorafenib and sotorasib in BRAF and KRAS colorectal (CRC) and non-small cell lung cancer (NSCLC) cell lines. Methods: Cell lines with BRAF V600E (HT29, CRC) and KRAS G12C mutations (H2122 and H23, NSCLC) were used. Anti-EGF VacAbs were obtained by immunizing rabbits with recombinant human EGF. Cell lines were treated with encorafenib or sotorasib in combination with anti-EGF VacAbs and the antitumor effects compared to the combination of encorafenib/cetuximab and sotorasib/panitumumab. Cell viability was determined by MTT, changes of total and phosphorylated proteins by Western blotting and emergence of resistance by direct microscopic examination in low density cultures. Results: Anti-EGF VacAbs suppressed the EGF-induced proliferation and blocked the EGFR signaling pathways more efficiently than cetuximab and panitumumab in KRAS and BRAF cell lines. In combination, anti-EGF VacAbs significantly enhanced the antitumor activity of encorafenib (in HT29 cells) and sotorasib (in H2122 and H23 cells), further suppressing EGFR, PRAS40 and ERK 1/2 phosphorylation. Also, the antitumor effects of the anti-EGF VacAbs in combination were superior to those of cetuximab and panitumumab. Finally, the addition of anti-EGF VacAbs to the culture medium significantly delayed the emergence of resistant clones to encorafenib (in HT29) and sotorasib (in H23). Again, the effect was more pronounced than the delay observed when adding cetuximab or panitumumab. Resistant clones generated under all combinations are being analyzed by NGS and Western blotting to determine the possible mechanisms of acquired resistance. Conclusions: Anti-EGF VacAbs potentiate the antitumor effects of encorafenib and sotorasib in cancer cell lines more efficiently than cetuximab and panitumumab. Our data provide a rationale for clinical trials testing the combination of anti-EGF VacAbs with targeted inhibitors in BRAF and KRAS mutant CRC and NSCLC patients. (1)“Anti-Epidermal Growth Factor Vaccine Antibodies Enhance the Efficacy of Tyrosine Kinase Inhibitors and Delay the Emergence of Resistance in EGFR Mutant Lung Cancer Cells” García-Roman S, Molina-Vila MA, et al. J Thorac Oncol. 2018. (2) “Anti-epidermal growth factor vaccine antibodies increase the antitumor activity of kinase inhibitors in ALK and RET rearranged lung cancer cells” García-Roman S, Molina-Vila MA, et al. Transl. Oncol. 2020. Citation Format: Silvia Garcia-Roman, Miguel A. Molina-Vila, Erik d'Hondt, Rafael Rosell. Anti-EGF antibodies significantly improve the activity of BRAF and KRAS inhibitors in preclinical models [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 338.

Abstract 1180: Discovery of CC-91516, a potent and selective ERK/NLK inhibitor, with anti-tumor activity in preclinical cancer models harboring BRAF or CTNNB1 mutation

Abstract CC-91516 (also called CC0776314), a selective and potent inhibitor of ERK1/2 and NLK, was discovered via a phenotypic screen of a kinase-focused library for compounds that synergize with mTOR kinase inhibitor CC-223 to induce apoptosis in combination with CC-223. Broad kinase selectivity profiling identified ERK1/2 and NLK as targets of CC-91516. Crystal structure of CC-91516 in complex with ERK2 reveals that its 2, 4, 6-trichlorophenyl moiety binds to a unique back pocket of the adenosine-5′-triphosphate (ATP) binding site of ERK2, which is not accessible to other ERK inhibitors such as BVD-523 and GDC-0994. This unique binding mode of CC-91516 leads to a slow off-rate for its ERK binding with long residence time disrupting both the active and inactive ERK forms. Consequentially, CC-91516 causes sustained inhibition of the MAPK pathway in BRAF mutant colorectal cancer cells. In addition, CC-91516 also regulates Wnt/β-catenin and YAP pathways in multiple cancer cell lines. CC-91516 shows potent yet selective anti-proliferative activity against a large panel of cancer cell lines. Activating mutations in BRAF or CTNNB1 gene associate with sensitivity to CC-91516-mediated anti-proliferative activity while mutations in RB and PI3K/PTEN pathway associate with resistance. CC-91516 inhibits ex vivo colony formation of PDX models with BRAF and CTNNB1 mutations. In addition, CC-91516 potently induces apoptosis, inhibits survival, and overcomes resistance to MEK inhibitor trametinib of BRAF or CTNNB1 mutant cancer cells in long-term culture assay in vitro. CC-91516 has good oral bioavailability and shows excellent anti-tumor activity in vivo against both BRAF and CTNNB1 mutant xenograft models. DMPK and toxicology studies showed robust oral exposure across preclinical species. In summary, CC-91516 has demonstrated preclinical anti-tumor activities and DMPK and safety profiles in support of its clinical development. Citation Format: Shuichan Xu, Tam Tran, Dan Zhu, Tao Shi, David Mikolon, Jim Leisten, Philip Chamberlain, Laurie LeBrun, Sogole Bahmanyar, Ning Jiang, Jingjing Zhao, Mehnaz Malek, Ellen Filvaroff, Heather Raymon, Robert Hubbard, John Boylan. Discovery of CC-91516, a potent and selective ERK/NLK inhibitor, with anti-tumor activity in preclinical cancer models harboring BRAF or CTNNB1 mutation [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 1180.

Insight on BRAFV600E mutated colorectal cancer immune microenvironment.

Colorectal cancer (CRC) is the second deadliest malignancy for both sexes. The BRAFV600E mutation, one of the most common driver mutations in CRC, is known for its poor prognosis due to the increased risk of metastasis. The effect of the BRAFV600E mutation on the tumor microenvironment was the topic of the study reported in World Journal of Gastrointestinal Oncology, with special focus on immune status. The authors presented insightful findings that were exclusively based on macrophage polarity and cytokine levels, without investigating other relevant immune elements. A more comprehensive look into the dynamic immune activity of cancer environments will warrant more meaningful practical findings. In this letter, we discuss other significant immune factors and their possible implications on the tumor microenvironment of BRAF-mutated CRC.

BRAF-Mutated Advanced Colorectal Cancer: A Rapidly Changing Therapeutic Landscape.

BRAF-mutated advanced colorectal cancer is a relatively small but critical subset of this tumor type on the basis of prognostic and predictive implications. BRAF alterations in colorectal cancer are classified into three functional categories on the basis of signaling mechanisms, with the class I BRAFV600E mutation occurring most frequently in colorectal cancer. Functional categorization of BRAF mutations in colorectal cancer demonstrates distinct mitogen-activated protein kinase pathway signaling. On the basis of recent clinical trials, current standard-of-care therapies for patients with BRAFV600E-mutated metastatic colorectal cancer include first-line cytotoxic chemotherapy plus bevacizumab and subsequent therapy with the BRAF inhibitor encorafenib and antiepidermal growth factor receptor antibody cetuximab. Treatment regimens currently under exploration in BRAFV600E-mutant metastatic colorectal cancer include combinatorial options of various pathway-targeted therapies, cytotoxic chemotherapy, and/or immune checkpoint blockade, among others. Circumvention of adaptive and acquired resistance to BRAF-targeted therapies is a significant challenge to be overcome in BRAF-mutated advanced colorectal cancer.

Clinical and genomic distinction of class 1/2/3 BRAF-mutant colorectal cancer and differential prognosis.

3533 Background: Mutations occurring at the V600 amino acid of BRAF is the most common BRAF mutations in colorectal cancer (CRC), which lead to RAS-independent active monomers (Class 1) and are the targets of BRAF inhibitors. BRAF non-V600 mutants can be further classified as RAS-independent active dimers (Class 2) and RAS-dependent impaired kinase (Class 3). The clinical and genetic distinction of CRC patients carrying different subtypes of BRAF mutations remain to be revealed. Methods: A multicenter retrospective study investigated the mutational profiles of 2,118 CRC patients whose baseline tumor samples were analyzed between June 2015 and June 2020 using capture-based hybrid NGS targeting 400+ cancer-related genes. Clinical characteristics including age, sex, stage, and tumor location were analyzed. A public cBioPortal cohort of 471 metastatic CRC patients was used for survival analysis. Results: A total of 473 patients were identified to contain BRAF mutations and can be sub-grouped into Class 1 (N = 246), Class 2 (N = 29), Class 3 (N = 53), and others (N = 145). All Class 1 BRAF mutations were V600E, while the Class 2 and Class 3 mutations were predominantly G469 (52%) and D594 (56%), respectively. No difference in patient’s age, sex, and stage was observed among BRAF Class 1-3 subgroups, but the anatomical location of the tumor differed among subgroups, particularly between Class 1 and Class 3 BRAF-mutant patients significantly (p = 0.027). Specifically, 39% of tumors carrying Class 1 mutations occurred at the right colon, while the most frequent location of tumors with Class 3 mutations was rectum (58%). Mutational profiling revealed that KRAS and APC mutations were enriched in Class 2/3 compared to Class 1 BRAF-mutant patients, while RNF43 and SMAD4 mutations were more frequently observed in Class 1 patients. Mutations causing the activation of the Wnt or RTK/RAS signaling pathways were also more common in Class 2/3 subgroups comparing to Class 1 patients. Furthermore, based on the analysis of mutation allele frequency, Class 1 BRAF mutations tended to be drivers while Class 2/3 BRAF mutations were more likely to be passengers. In addition, mutational signature profiling showed that the NER signature was enriched in Class 1 BRAF-mutant patients but the APOBEC signature in Class2/3 classes. The tumor mutational burden of Class 2 BRAF tumors was higher than the other two subgroups (median: 10.4 vs 7.6 and 8.4), and microsatellite instability-high tumors were more common in Class 1 (11% vs 7% and 4%). In the cBioPortal cohort, Class 1 BRAF-mutant patients had the worst overall survival whereas Class 3 patients demonstrated the best prognosis. Conclusions: The clinical and genetic features of CRC patients harboring Class 2 and 3 BRAF mutations were different from those carrying Class 1 BRAF mutations in aspects including tumor location, concurrent mutations, mutational signatures, as well as survival outcomes.

P-11 Venous thromboembolism in colorectal cancer patients with BRAF mutation

Venous thromboembolism (VTE) is a frequent complication in colorectal cancer (CRC) patients. In these patients, some molecular biomarkers, such as KRAS mutation, have been associated with an increased risk of thrombosis. However, little is known about the characteristics of VTE associated with less prevalent molecular biomarkers. The aim of this analysis is to describe the characteristics of VTE of a cohort of ambulatory CRC patients harboring BRAF mutation. We performed a retrospective review of consecutive patients with BRAF-mutated CRC attended in the Medical Oncology Department of 10 hospitals from the network of the Cancer & Thrombosis Section of the Spanish Society of Medical Oncology (SEOM). Between January 2014 and June 2018, 165 patients were identified and included in the analysis. Mean age was 63.47 years (standard deviation [SD] 11.50 years) and 46.7% (n=77) were men. With a median follow-up of 15 months (interquartile range [IQR] 9-25), forty patients (24.2%) developed a VTE (32.4% pulmonary embolism, 24.3% lower-extremity deep-vein thrombosis [DVT], 2.7% upper-extremity DVT, 16.2% visceral thrombosis, 18.9% catheter related-thrombosis, 5.4% others). Most patients had metastatic disease (90.0%) and was receiving systemic therapy (73.7%). Median time from CRC diagnosis to VTE was 5.06 months (IQR 2.85-10.81). 50.0% of events were diagnosed incidentally and 75.0% in the ambulatory setting. Most patients (87.5%) received anticoagulant treatment (low-molecular-weight heparins [LMWH] 33 patients, direct oral anticoagulants [DOACs] 1 patient, others 1 patient), 35.9% for more than 6 months. 6 patients (15.4%) experienced VTE recurrence and 7 patients (19.4%) bleeding (mayor or fatal bleeding 4 patients). Median survival was 20.86 months for non-VTE patients and 11.30 months for VTE patients (hazard-ratio [HR] 2.13; CI 95% 1.38-3.28; p=0.001). VTE is associated with increased morbidity and mortality in patients with BRAF-mutated CRC.

P-57 An observational/translational study of BRAF inhibitor combination therapy for BRAF-mutant metastatic colorectal cancer including biomarker research: BEETS trial (JACCRO CC-18)

BRAF inhibitor combination therapy became the standard of care for BRAF -mutated metastatic colorectal cancer (mCRC) based on the BEACON CRC trial, which showed a survival benefit of the three-drug combination regimen with BRAF and MEK inhibitors plus anti-EGFR antibody as well as the two-drug combination regimen with BRAF inhibitor and anti-EGFR antibody over standard chemotherapy. The two-drug combination regimen is approved in Europe and the US, while both three- and two-drug combination regimens are approved in Japan.

BRAF-mutant metastatic colorectal cancer: Prognostic and predictive value of primary tumor location—A pooled analysis of the AIO studies FIRE-1, CIOX, XELAVIRI, FIRE-3, and VOLFI.

3576 Background: Primary tumor location (PTL: left vs. right) is an established prognostic marker in metastatic colorectal cancer (mCRC) and has predictive impact for anti-EGFR antibody (mAb) efficacy in patients with RAS ( KRAS and NRAS) wild-type (WT) mCRC. This analysis of five pooled studies evaluates PTL as a prognostic and - concerning anti-EGFR mAb efficacy - predictive marker in BRAF V600E-mutant/ RAS WT and mCRC. Methods: The analysis is based on individual patient data of five pooled 1st-line studies with varying treatment strategies: the pooled population comprises of BRAF V600E-mutant/ RAS WT ( BRAFmt) mCRC with known PTL. For analysis, treatment was stratified into two groups: treated with or without anti-EGFR mAb. Dichotomous variables (overall response rate, ORR; characteristics) were compared by Chi-Square or Fisher’s exact test and time-to event endpoints (progressive-free survival, PFS; overall survival, OS) by Kaplan-Meier method, log rank test and Cox regression. Results: Of 102 patients (pts) with BRAFmt mCRC, 55 pts (54%) presented with right-sided primary tumors (RPT), 47 (46%) presented with left-sided primary tumors (LPT). Pts with RPT were more likely to be female ( p= 0.04). ORR was inferior in RPT compared to LPT (35% vs. 55%; p= 0.04). No difference was seen in PFS (HR 0.8 (95% CI 0.6-1.3; p= 0.32) or OS (HR 0.8; 95% CI 0.8-1.3; p= 0.46). In male pts PTL trended to be associated with longer OS (HR 0.6; 95% CI 0.3-1.0; p= 0.06). 25 pts with RPT (45%) and 21 with LPT (45%) received anti-EGFR mAb. In pts with LPT anti-EGFR mAb based treatment was associated with higher ORR (81% vs. 35%; p< 0.01). No effect was seen in RPT (ORR 35% vs. 36%; p= 0.82). Anti-EGFR mAb treatment resulted in inferior PFS in RPT (HR 2.0; 95% CI 1.1-3.5; p= 0.02) and showed a trend towards improved PFS in LPT (HR 0.6; 95% CI 0.3-1.1; p= 0.11). Pts with RPT had a worse OS when treated with anti-EGFR mAb (HR 1.8; 95% CI 1.0-3.1; p= 0.05), whereas pts with LPT appeared to have a favorable outcome when treated with an anti-EGFR mAb containing regimen (HR 0.4; 95% CI 0.2-0.7; p< 0.01). Conclusions: This exploratory analysis of five studies suggests that PTL has limited prognostic impact in BRAFmt mCRC but might carry predictive information regarding anti-EGFR mAb efficacy in a 1st-line treatment setting. Further prospective studies are needed to validate these results and to grasp the differences in the heterogeneous group of BRAFmt pts. Clinical trial information: FIRE-1 was before mandatory registration, NCT00254137, NCT00433927, NCT01249638, NCT01328171.

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

Simple SummaryThe present study demonstrated that the distinct subgroup of BRAF-MT CRC showed a good response after palliative chemotherapy. Based on the immune profile analysis, higher PD-L1 expression and CD8-positive cell infiltration were shown in this study population. Furthermore, the assessment of the immune profile of BRAF-MT tumors can be helpful to better understand tumor biology and the different clinical outcomes of BRAF-MT CRC. 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.

PO-20: Incidence of venous thromboembolism in patients with BRAF-mutated colorectal cancer

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The evolving landscape of BRAF inhibitors in BRAF mutant colorectal cancer and the added value of cytotoxic chemotherapy

The evolving landscape of BRAF inhibitors in BRAF mutant colorectal cancer and the added value of cytotoxic chemotherapy