BACKGROUND: BRAF mutation has been recognized as a negative prognostic marker for metastatic colorectal cancer (mCRC), but these data are from common BRAF V600E-mutated mCRC. Combination therapy of BRAF inhibitor and anti-epidermal growth factor receptor (EGFR) antibody has been approved for BRAF V600E-mutated mCRC. However, BRAF non-V600 mutations are rare mutations, and their clinical behavior is not understood. Moreover, the BRAF K601E mutation is extremely rare in mCRC, and there have been no reports on its specific treatment.
METHODS: Herein, we report the case of a 59-year-old female with super aggressive mCRC with multiple metastases, which extended to whole body including mediastinal to abdominal lymph nodes, bones, pleura, and peritoneum. The companion diagnostics of tumor tissues showed RAS/BRAF wild-type without microsatellite instability. She received chemotherapy with mFOLFOX6 (oxaliplatin plus infusional 5-fluorouracil [5-FU] and leucovorin) plus panitumumab, following FOLFIRI (irinotecan plus infusional 5-FU and leucovorin) plus ramucirumab. For the next regimen selection, a comprehensive genomic profiling panel was performed and revealed a BRAF K601E mutation, which was not covered in the initial companion diagnostics. After disease progression, a combination of encorafenib, binimetinib, and cetuximab was selected as third-line chemotherapy. The serum levels of tumor markers were immediately decreased accompanied by improvements in pleural effusion and ascites. However, the disease progressed again, and best supportive care was done instead.
CONCLUSIONS: This case offers novel insights into the clinical behaviors of BRAF non-V600E-mCRC, potentially advancing personalized therapy for rare and aggressive cases.

UNASSIGNED: The development of new and changing melanocytic lesions has been increasingly reported as an adverse dermatologic toxicity of BRAF inhibitor therapy. Melanocytic lesions and melanomas induced by BRAF inhibitor therapy that lack BRAF V600E expression have been less commonly described. One mechanism that has been proposed for the development of BRAF inhibitor-induced melanocytic lesions, including those lacking BRAF V600E expression, is the paradoxical activation of the MAPK signaling pathway in BRAF wild-type (BRAFWT) cells.
UNASSIGNED: Herein, we report a rare case of a 39-year-old woman who developed numerous BRAF V600E-negative eruptive melanocytic nevi following encorafenib, cetuximab, and binimetinib combination therapy, the current standard of care for the treatment of BRAF-mutant metastatic colorectal cancer.
UNASSIGNED: Patients treated with BRAF inhibitors, with or without related combination therapies, who develop BRAFWT melanocytic lesions are at risk for developing both dysplastic nevi and melanoma, thereby warranting baseline dermatoscopic evaluation prior to the initiation of therapy as well as regular follow-up during and after treatment.

UNASSIGNED: Encorafenib and binimetinib, a combination of BRAF and MEK inhibitors, is a standard of care for patients with advanced BRAFV600-mutant melanoma. This combination is known to have gastrointestinal side effects, most of which are mild and managed symptomatically. However, very few studies have reported severe colitis.
UNASSIGNED: We report here 2 patients with advanced melanoma who developed severe ulcerated right colitis manifested by diarrhea and hematochezia while being treated with encorafenib and binimetinib after immune checkpoint therapy.
UNASSIGNED: This rare but serious adverse event was not described in early phase 3 trials but has emerged in recent years, particularly with the sequential use of immune checkpoint inhibitors followed by BRAF/MEK inhibitors. In a comprehensive review of the existing literature, we identified 20 cases of severe colitis due to BRAF/MEK inhibitors. Clinical, endoscopic, and histological features are described to provide insight into the current understanding of this poorly understood clinical entity.

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Two new treatments have recently become standard care for patients with metastatic colorectal cancer (mCRC): encorafenib (BRAF inhibitor) associated with cetuximab (anti-EGFR) in the second or third line of chemotherapy for BRAF V600E tumors, and pembrolizumab (an anti PD-1 immune checkpoint inhibitor) for tumors harboring microsatellite instability (MSI)-high and/or deficient mismatch repair (dMMR). Furthermore, 30% of BRAF V600E mutated mCRC are MSI/dMMR through a sporadic hypermethylation of the promoter of hMLH1. We report here, for the first time, the case of a patient with BRAF V600E, PIK3CA, and SMAD4 mutated and dMMR/MSI mCRC, in whom we observed an atypical response pattern under the sequence of pembrolizumab followed by the doublet encorafenib and cetuximab treatment. The patient was progressive after a single cycle of pembrolizumab followed by a rapid complete response after only 2 months of treatment with encorafenib and cetuximab, discovered during R0 cytoreduction surgery for peritoneal carcinomatosis.

Sixty percent of patients with stage IV melanoma may develop brain metastases, which result in significantly increased morbidity and a poor overall prognosis. Phase 3 studies of melanoma usually exclude patients with untreated brain metastases; therefore, clinical data for intracranial responses to treatments are limited.
A multicenter, retrospective case series investigation of consecutive BRAF-mutant patients with melanoma brain metastases (MBMs) treated with a combination of BRAF inhibitor encorafenib and MEK inhibitor binimetinib was conducted to evaluate the antitumor response. Assessments included the intracranial, extracranial, and global objective response rates (according to the modified Response Evaluation Criteria in Solid Tumors, version 1.1); the clinical benefit rate; the time to response; the duration of response; and safety.
A total of 24 patients with stage IV BRAF-mutant MBMs treated with encorafenib plus binimetinib in 3 centers in the United States were included. Patients had received a median of 2.5 prior lines of treatment, and 88% had prior treatment with BRAF/MEK inhibitors. The intracranial objective response rate was 33%, and the clinical benefit rate was 63%. The median time to a response was 6 weeks, and the median duration of response was 22 weeks. Among the 21 patients with MBMs and prior BRAF/MEK inhibitor treatment, the intracranial objective response rate was 24%, and the clinical benefit rate was 57%. Similar outcomes were observed for extracranial and global responses. The safety profile for encorafenib plus binimetinib was similar to that observed in patients with melanoma without brain metastases.
Combination therapy with encorafenib plus binimetinib elicited intracranial activity in patients with BRAF-mutant MBMs, including patients previously treated with BRAF/MEK inhibitors. Further prospective studies are warranted and ongoing.