Molecular mechanisms underlying the resistance of BRAF V600E-mutant metastatic colorectal cancer to EGFR/BRAF inhibitors

BRAF V600E-mutant colorectal cancer with CNS metastases treated successfully with encorafenib, binimetinib and cetuximab

This report describes a case of BRAF V600E-mutated colorectal cancer with CNS metastases in which treatment with encorafenib, binimetinib and cetuximab was effective. There is limited information on the ability of encorafenib, binimetinib and cetuximab to enter the CNS.The patient was a 53-year-old man was diagnosed with ascending colon cancer (cT3N3M1c stage IVc). BRAF V600E mutation was confirmed. FOLFOX was started, but CNS metastases soon appeared. Encorafenib, binimetinib and cetuximab were administered and had a favorable effect on the CNS lesions. The patient initially responded well, but his disease progressed 2 months later. Further research is needed to improve management strategies for BRAF V600E-mutated colorectal cancer with CNS metastases.

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.

Liquid biopsy in colorectal cancer: Onward and upward

Colorectal cancer (CRC) remains a leading cause of cancer-related deaths worldwide. In recent years, liquid biopsy has emerged as one of the most interesting areas of research in oncology, leading to innovative trials and practical changes in all aspects of CRC management. RNAs and cell free DNA (cfDNA) methylation are emerging as promising biomarkers for early diagnosis. Post-surgical circulating tumour DNA (ctDNA) can aid in evaluating minimal residual disease and personalising adjuvant treatment. In rectal cancer, ctDNA could improve response assessment to neoadjuvant therapy and risk stratification, especially in the era of organ-preservation trials. In the advanced setting, ctDNA analysis offers the opportunity to monitor treatment response and identify driver and resistance mutations more comprehensively than traditional tissue analysis, providing prognostic and predictive information. The aim of this review is to provide a detailed overview of the clinical applications and future perspectives of liquid biopsy in CRC.

Ezrin Inhibition Overcomes Acquired Resistance to Vemurafenib in BRAFV600E-Mutated Colon Cancer and Melanoma Cells In Vitro

Despite the advancements in targeted therapy for BRAFV600E-mutated metastatic colorectal cancer (mCRC), the development of resistance to BRAFV600E inhibition limits the response rate and durability of the treatment. Better understanding of the resistance mechanisms to BRAF inhibitors will facilitate the design of novel pharmacological strategies for BRAF-mutated mCRC. The aim of this study was to identify novel protein candidates involved in acquired resistance to BRAFV600E inhibitor vemurafenib in BRAFV600E-mutated colon cancer cells using an integrated proteomics approach. Bioinformatic analysis of obtained proteomics data indicated actin-cytoskeleton linker protein ezrin as a highly ranked protein significantly associated with vemurafenib resistance whose overexpression in the resistant cells was additionally confirmed at the gene and protein level. Ezrin inhibition by NSC305787 increased anti-proliferative and pro-apoptotic effects of vemurafenib in the resistant cells in an additive manner, which was accompanied by downregulation of CD44 expression and inhibition of AKT/c-Myc activities. We also detected an increased ezrin expression in vemurafenib-resistant melanoma cells harbouring the BRAFV600E mutation. Importantly, ezrin inhibition potentiated anti-proliferative and pro-apoptotic effects of vemurafenib in the resistant melanoma cells in a synergistic manner. Altogether, our study suggests a role of ezrin in acquired resistance to vemurafenib in colon cancer and melanoma cells carrying the BRAFV600E mutation and supports further pre-clinical and clinical studies to explore the benefits of combined BRAF inhibitors and actin-targeting drugs as a potential therapeutic approach for BRAFV600E-mutated cancers.

The BEETS (JACCRO CC-18) trial: an observational and translational study of BRAF-mutated metastatic colorectal cancer

For BRAF V600E-mutated metastatic colorectal cancer (mCRC), the BEACON phase 3 trial showed survival benefit of triplet therapy with cetuximab (anti-EGFR antibody), encorafenib (BRAF inhibitor) and binimetinib (MEK inhibitor) as well as doublet therapy with cetuximab and encorafenib over irinotecan-based chemotherapy plus anti-EGFR antibody. Both regimens are standards of care in Japan, but definite biomarkers for predicting efficacy and selecting treatment remain lacking. The mechanisms underlying resistance to these regimens also warrant urgent exploration to further evolve treatment. This prospective observational/translational study evaluated real-word clinical outcomes with cetuximab and encorafenib with or without binimetinib for BRAF-mutated mCRC patients and investigated biomarkers for response and resistance by collecting blood samples before and after treatment. Clinical Trial Registration: UMIN000045530 (https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000051983).

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.

Secretome Screening of BRAFV600E-Mutated Colon Cancer Cells Resistant to Vemurafenib

Patients with metastatic colorectal cancer (mCRC) carrying BRAFV600E mutation have worse response to chemotherapy and poor prognosis. The BRAFV600E inhibitor vemurafenib has shown modest efficacy as monotherapy in BRAF-mutated mCRC due to the development of resistance. The aim of this study was to conduct a comparative proteomics profiling of the secretome from vemurafenib-sensitive vs. -resistant colon cancer cells harboring BRAFV600E mutation in order to identify specific secretory features potentially associated with changes in the resistant cells' phenotype. Towards this aim, we employed two complementary proteomics approaches including two-dimensional gel electrophoresis coupled with MALDI-TOF/TOF mass spectrometry and label-free quantitative LC-MS/MS analysis. Obtained results pointed to aberrant regulation of DNA replication and endoplasmic reticulum stress as the major secretome features associated with chemoresistant phenotype. Accordingly, two proteins implicated in these processes including RPA1 and HSPA5/GRP78 were discussed in more details in the context of biological networks and their importance as potential secretome targets for further functional and clinical evaluation. Expression patterns of RPA1 and HSPA5/GRP78 in tumor tissues from colon cancer patients were also found in additional in silico analyses to be associated with BRAFV600E mutation status, which opens the possibility to extrapolate our findings and their clinical implication to other solid tumors harboring BRAFV600E mutation, such as melanoma.

Clinical significance and diagnostic value of QPCT, SCEL and TNFRSF12A in papillary thyroid cancer

PURPOSE

To identify specific novel genes that could be used as diagnostic and prognostic factors in papillary thyroid carcinoma (PTC).

METHODS

Screening of differential genes by RNA sequencing (RNA-Seq) in normal thyroid, Hashimoto's thyroiditis, PTC combined with Hashimoto's thyroiditis and PTC tissues. The genes QPCT, SCEL and TNFRSF12A were selected by qRT-PCR and immunohistochemical pre-experiments. The GEPIA2 database, qRT-PCR, and immunohistochemical studies were used to confirm the target genes QPCT, SCEL, and TNFRSF12A. ROC curves were used to assess the diagnostic usefulness of these 3 genes for PTC in more detail.

RESULTS

Functional enrichment analysis showed that QPCT, SCEL and TNFRSF12A were enriched in the pathways for peptidyl-pyroglutamic acid biosynthesis, keratinocyte differentiation, WNT signaling, apoptosis. GEPIA2 database analysis revealed that QPCT, SCEL and TNFRSF12A were high in thyroid cancer, and TC patients with lower TNFRSF12A levels had short survival. QPCT, SCEL and TNFRSF12A were elevated in PTC and thyroid adenoma. The mRNA diagnostic values were as follows: for QPCT, AUROC = 0.891, 95% CI, 0.835-0.947; for SCEL, AUROC = 0.921, 95% CI, 0.869-0.974; for TNFRSF12A, AUROC = 0.884, 95% CI, 0.809-0.958. Immunohistochemical results showed that QPCT, SCEL, and TNFRSF12A differed to varying degrees between subgroups of thyroid tissue. SCEL was associated with BRAF V600E mutation status and stratification of recurrence risk, while TNFRSF12A was associated with Cyclin D1. The protein diagnostic values were as follows: for QPCT, AUROC = 0.752, 95% CI, 0.685-0.819; for SCEL, AUROC = 0.715, 95% CI, 0.645-0.784; for TNFRSF12A, AUROC = 0.660, 95% CI, 0.587-0.734.

CONCLUSION

QPCT, SCEL and TNFRSF12A are expected to be diagnostic markers for PTC.