Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.12.2 (MEK)
 18,161 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pleomorphic xanthoastrocytoma (PXA) is a World Health Organization Grade 2 glioma that is uncommon (<1 % all adult gliomas) and seen primarily in children and young adults. PXA has been demonstrated to manifest the V600E BRAF mutation in nearly 70 % of all tumors, a mutation that constitutively activates the BRAF/MEK signaling pathway. Assess response and toxicity of a BRAF inhibitor, vemurafenib, in recurrent PXA manifesting the V600E mutation. Four adults [2 males; 2 female: median age 45 years (range 34-53)] with surgery, radiation and alkylator refractory recurrent PXA demonstrating the BRAF mutation (V600E) were treated with vemurafenib. A cycle of vemurafenib was defined as 4 weeks of continuous therapy. All toxicities seen were grade 2 and included arthralgia, photosensitivity, fatigue and nausea (1 patient each). The median number of cycles of therapy was 5 (range 2-10). Radiographic response was progressive disease in 1, stable disease in 2 and partial response in 1. Median progression free survival was 5 months (range 2-10 months). Median overall survival was 8 months (range 4-14 months). In this small retrospective series of select patients with recurrent PXA manifesting the BRAF V600E activating mutation, vemurafenib appears to have single agent activity with manageable toxicity. Confirmation in a larger series of similar patients is required.
 ...
PMID:Salvage therapy with BRAF inhibitors for recurrent pleomorphic xanthoastrocytoma: a retrospective case series. 2375 28

Pleomorphic xanthoastrocytoma (PXA) is a World Health Organization (WHO) Grade II glioma occurring primarily in children and young adults. Most PXAs harbor the known activating mutation BRAF V600E. We report a case of locally recurrent PXA with anaplastic features in a 10-yr-old female. The PXA was negative by immunohistochemical (IHC) staining for BRAF V600E mutation. Whole-exome and transcriptome sequencing of the tumor confirmed the absence of BRAF V600E, but identified copy-number alterations (including loss of the tumor suppressor CDKN2A) and a novel TMEM106B-BRAF fusion. Based on similar BRAF fusion proteins, this novel fusion is predicted to result in activation of BRAF signaling. Demonstration of positive IHC for phospho-ERK1/2 and phospho-MEK1/2 supported this prediction, and implicated MEK inhibitors as a potential therapeutic strategy.
 ...
PMID:A novel, potentially targetable TMEM106B-BRAF fusion in pleomorphic xanthoastrocytoma. 2829 58

Pleomorphic xanthoastrocytoma is a rare brain tumor with unique high frequency of BRAF V600E mutation which is plausible for targeted therapy. The anaplastic variant has generally worse prognosis. We present an adolescent patient with a disseminated relapse of anaplastic pleomorphic xanthoastrocytoma following surgery, radiotherapy, and chemotherapy. She had a dramatic and prolonged response to a BRAF inhibitor (Dabrafinib) and later to addition of a MEK inhibitor (Trametinib) on tumor progression. With minimal side effects and a good quality of life, the patient is alive more than 2 years after initiation of targeted therapy. This experience confirms the potential role of targeted treatments in high-grade BRAF-mutated brain tumors.
 ...
PMID:Sustained Response to Targeted Therapy in a Patient With Disseminated Anaplastic Pleomorphic Xanthoastrocytoma. 2920 Jan 56

Pleomorphic xanthoastrocytoma (PXA) is a rare primary central nervous system tumor which frequently harbors mutations in BRAF. Anaplastic PXA follow a more aggressive course than their nonanaplastic counterparts. We present the case of an anaplastic PXA initially treated with the BRAF inhibitor vemurafenib. After progression of disease the MEK inhibitor trametinib was added to the regimen leading to radiographic improvement. The rationale for combined BRAF and MEK inhibition in PXA is reviewed.
 ...
PMID:Response to BRAF/MEK Inhibition After Progression With BRAF Inhibition in a Patient With Anaplastic Pleomorphic Xanthoastrocytoma. 3016 70

Pleomorphic xanthoastrocytoma (PXA) is a slow-growing neoplasm that predominantly affects the pediatric and young adult population. This neoplasm has a good prognosis, with a median 10-year survival rate of 70%. The majority of tumors are supratentorial and arise in the temporal lobe, while spinal tumors are extremely rare, with only 8 reported cases. Molecular perturbations involving the MAPK/ERK signaling pathway have been described in PXAs. The most common mutation is BRAF V600E in 60%-80% of cases. Other mechanisms activating this pathway in the absence of this mutation are rare and include CRAF (RAF1) fusion genes. We report a PXA case in the cervical spinal cord of a 49-year-old man with slowly progressive coordination difficulties and extremity numbness. The tumor was negative for the V600E mutation, but 2 RNA sequencing platforms detected a QKI-RAF1 fusion (t(6; 3)(q26; p25)), which has not been previously reported in PXAs. This fusion is known to activate MAPK/ERK and PI3K/mTOR signaling. Although first- and second-generation RAF inhibitors are predicted to be ineffective, this fusion may be targetable by the novel RAF inhibitor LY3009120 and to some extent by the MEK inhibitor trametinib. Genetic analysis to screen for MAPK/ERK pathway mutations is warranted on PXAs negative for the V600E mutation.
 ...
PMID:Spinal Pleomorphic Xanthoastrocytoma With a QKI-RAF1 Fusion. 3051 58