Triple-Regimen of Vemurafenib, Irinotecan, and Cetuximab for the Treatment of BRAFV600E-Mutant CRC: A Case Report and Review

Signature Gene Mutations in Colorectal Cancer: Potential Neoantigens for Cancer Vaccines

Colorectal cancer (CRC), the third most common cancer worldwide, is one of the deadliest cancers. CRC is known as a cold tumor, characterized by a low immune response that makes it difficult for immune cells to infiltrate and exhibits strong resistance to immunotherapy with checkpoint inhibition. This restricted response is largely attributed to signature gene mutations including mismatch repair (MMR) genes, KRAS, BRAF, APC, and TP53, which are also the main oncogenes in CRC. Mutated signature genes continuously upregulate abnormal signaling pathways, leading to excessive proliferation, cancer progression, and metastasis. Furthermore, it reorganizes the tumor microenvironment (TME) by recruiting immunosuppressive cells. However, the mutation can produce neoantigens that can provoke an immune response, making it a potential target for immunotherapy. In particular, cancer vaccines that leverage the strong neoantigenic properties of these mutations are considered promising for overcoming immune resistance and eliciting anti-tumor responses. In this review, we will describe signature gene mutations in CRC and focus on cancer vaccines targeting these mutations as potential therapies for CRC.

Safety and Efficacy of Regorafenib and 5-Fluorouracil Combination Therapy in Refractory Metastatic Colorectal Cancer After Third-Line Treatment: An Institutional Experience

Background: Colorectal carcinoma (CRC) is one of the most common cancer types along with breast, prostate, and lung cancer. Many patients with CRC present with metastatic disease despite receiving standard first- and second-line therapies; thus emerges the demand for implementing new therapies that could improve outcomes among CRC patients. This case series was conducted to assess the efficacy and safety of regorafenib plus 5-fluorouracil (5-FU) in patients with refractory metastatic CRC (mCRC). Methods: We conducted a retrospective analysis of data from adult patients aged 18 and above who were diagnosed with refractory mCRC and received regorafenib plus 5-FU combination therapy at Houston Methodist Hospital between November 2017 and October 2023. Our study focuses on assessing key outcomes, including Overall Survival [OS], Progression-Free Survival [PFS], and safety. Results: Among the 12 patients we included in this study who underwent regorafenib plus 5-FU combination therapy for refractory mCRC after receiving at least three prior lines of treatment, the best response for six patients (50%) was successfully achieved, with disease control within 7-12 weeks from therapy initiation. Patients had an overall good tolerance for this treatment regimen and reported only the most common adverse events, including Hand-Foot Syndrome (HFS), mucositis, and hypertension (HTN), which were mostly resolved with dose adjustment of medications. Conclusions: This study highlights that using a combination of regorafenib plus 5-FU can be a potential treatment option for patients with refractory mCRC. Additional research, including prospective clinical trials, is required to assess the effectiveness and safety of regorafenib and 5-FU combination therapy in comparison to other currently limited treatment options.

BRAF Targeting Across Solid Tumors: Molecular Aspects and Clinical Applications

BRAF mutations are critical drivers in cancers such as melanoma, colorectal cancer, and non-small-cell lung cancer. The most common mutation, BRAF V600E, is a key therapeutic target. Targeted treatments with BRAF and MEK inhibitors have significantly improved progression-free and overall survival in melanoma patients. However, in cancers like metastatic colorectal cancer, BRAF mutations are associated with poor outcomes due to aggressive disease behavior and resistance to conventional chemotherapy. Despite progress, resistance to BRAF/MEK inhibitors remains a major challenge, often driven by secondary mutations in the mitogen-activated protein kinase (MAPK) pathway, activation of alternative pathways such as phosphoinositide 3-kinases (PI3Ks)/protein kinase B (AKT), or changes in the tumor microenvironment. These challenges have motivated ongoing research into combining BRAF inhibitors with immunotherapies to enhance and prolong treatment effectiveness. Future research must also account for the role of the cancer's tissue of origin, as the biological context significantly influences response to targeted therapies, highlighting the need for a deeper understanding of tumor biology, micro-environment, and genetics.

Antitumor activity of the new tyrphostin briva against BRAFV600E-mutant colorectal carcinoma cells

Because of a reduced sensitivity of BRAF-mutant colorectal cancers to BRAF inhibitor treatment when compared with BRAF-mutant melanoma, it is essential to develop efficient drugs to cope with this disease. The new 2-(4-bromophenyl)-3-arylacrylonitrile compound Briva was prepared in one step from commercially available starting compounds. Briva and two known thiophene analogs (Thio-Iva and Thio-Dam) were tested for their cytotoxic activity against various tumor cell lines including colorectal and breast cancer cells. The antitumor activities of the test compounds were assessed in vitro via the MTT assay, DAPI staining of nuclei, RT-PCR and immunoblotting, wound healing, clonogenic assay, collagen I adhesion assay, and kinase inhibition assays. A selective activity of Briva was observed against BRAFV600E-mutant HT-29 and COLO-201 colorectal carcinoma (CRC) cells. Briva caused inhibition of HT-29 clonogenic tumor growth and was found to induce cytotoxicity by activating the intrinsic apoptosis pathway. In addition, Briva reduced HT-29 cell adhesion and migration. Kinase inhibition experiments revealed that Briva inhibits VEGFR2. Thus, Briva can be considered as a promising antitumor compound against BRAFV600E-mutant colon carcinoma by targeting VEGFR2 tyrosine kinase and consequently reducing cell adhesion and metastasis formation.

Case report: Efficacy and safety of regorafenib plus fluorouracil combination therapy in the treatment of refractory metastatic colorectal cancer

Background

More than half of patients with colorectal cancer (CRC) present with metastatic disease or develop recurrent disease on first-line and second-line options. Treatment beyond the second line remains an area of unmet need for patients with progressive or recurrent disease.

Methods

We retrospectively reviewed data of adult (>18 years old) patients with mCRC who received regorafenib + 5FU combination therapy at Houston Methodist Hospital with outcomes of interest including response rate, discontinuation due to side effects, and overall survival.

Results

Seven patients received regorafenib + 5FU combination therapy for mCRC after receiving at least two other lines of therapy (including at least one fluorouracil-based therapy). Four patients (57%) achieved disease control in 7-12 weeks after therapy initiation while three patients developed recurrent disease. In patients who achieved disease control, no new adverse events were reported among patients with this combination.

Conclusion

Regorafenib and Fluorouracil combination could be considered an option beyond the second line for patients with treatment-refractory metastatic colorectal cancer. Further studies, including a prospective trial, are needed to investigate the efficacy and safety of regorafenib plus 5FU therapy compared to other limited available therapies.

Timeline of FDA-Approved Targeted Therapy for Cholangiocarcinoma

Cholangiocarcinoma (CCA) represents approximately 3% of gastrointestinal malignancies worldwide and constitutes around 10-15% of all primary liver cancers, being only second to hepatocellular carcinoma. Mortality from CCA has been on the rise in recent decades, and in the United States alone there has been a 36% increase in CCA from 1999 to 2014, with over 7000 CCA mortalities since 2013. Targeted therapies, which have been gaining interest due to their greater specificity toward cancer cells, have only recently started gaining FDA approval for the treatment of CCA. In this manuscript, we will go through the timeline of current FDA-approved targeted therapies as well as those that have gained FDA breakthrough therapy designation.