6xfp
Crystal Structure of BRAF kinase domain bound to Belvarafenib
Structural highlights
DiseaseBRAF_HUMAN Note=Defects in BRAF are found in a wide range of cancers.[1] Defects in BRAF may be a cause of colorectal cancer (CRC) [MIM:114500.[2] Defects in BRAF are involved in lung cancer (LNCR) [MIM:211980. LNCR is a common malignancy affecting tissues of the lung. The most common form of lung cancer is non-small cell lung cancer (NSCLC) that can be divided into 3 major histologic subtypes: squamous cell carcinoma, adenocarcinoma, and large cell lung cancer. NSCLC is often diagnosed at an advanced stage and has a poor prognosis.[3] [4] Defects in BRAF are involved in non-Hodgkin lymphoma (NHL) [MIM:605027. NHL is a cancer that starts in cells of the lymph system, which is part of the body's immune system. NHLs can occur at any age and are often marked by enlarged lymph nodes, fever and weight loss.[5] [6] Defects in BRAF are a cause of cardiofaciocutaneous syndrome (CFC syndrome) [MIM:115150; also known as cardio-facio-cutaneous syndrome. CFC syndrome is characterized by a distinctive facial appearance, heart defects and mental retardation. Heart defects include pulmonic stenosis, atrial septal defects and hypertrophic cardiomyopathy. Some affected individuals present with ectodermal abnormalities such as sparse, friable hair, hyperkeratotic skin lesions and a generalized ichthyosis-like condition. Typical facial features are similar to Noonan syndrome. They include high forehead with bitemporal constriction, hypoplastic supraorbital ridges, downslanting palpebral fissures, a depressed nasal bridge, and posteriorly angulated ears with prominent helices. The inheritance of CFC syndrome is autosomal dominant.[7] Defects in BRAF are the cause of Noonan syndrome type 7 (NS7) [MIM:613706. Noonan syndrome is a disorder characterized by facial dysmorphic features such as hypertelorism, a downward eyeslant and low-set posteriorly rotated ears. Other features can include short stature, a short neck with webbing or redundancy of skin, cardiac anomalies, deafness, motor delay and variable intellectual deficits.[8] [9] Defects in BRAF are the cause of LEOPARD syndrome type 3 (LEOPARD3) [MIM:613707. LEOPARD3 is a disorder characterized by lentigines, electrocardiographic conduction abnormalities, ocular hypertelorism, pulmonic stenosis, abnormalities of genitalia, retardation of growth, and sensorineural deafness.[10] [11] Note=A chromosomal aberration involving BRAF is found in pilocytic astrocytomas. A tandem duplication of 2 Mb at 7q34 leads to the expression of a KIAA1549-BRAF fusion protein with a constitutive kinase activity and inducing cell transformation.[12] FunctionBRAF_HUMAN Involved in the transduction of mitogenic signals from the cell membrane to the nucleus. May play a role in the postsynaptic responses of hippocampal neuron. Publication Abstract from PubMedAlthough RAF monomer inhibitors (type I.5, BRAF(V600)) are clinically approved for the treatment of BRAF(V600)-mutant melanoma, they are ineffective in non-BRAF(V600) mutant cells(1-3). Belvarafenib is a potent and selective RAF dimer (type II) inhibitor that exhibits clinical activity in patients with BRAF(V600E)- and NRAS-mutant melanomas. Here we report the first-in-human phase I study investigating the maximum tolerated dose, and assessing the safety and preliminary efficacy of belvarafenib in BRAF(V600E)- and RAS-mutated advanced solid tumours (NCT02405065, NCT03118817). By generating belvarafenib-resistant NRAS-mutant melanoma cells and analysing circulating tumour DNA from patients treated with belvarafenib, we identified new recurrent mutations in ARAF within the kinase domain. ARAF mutants conferred resistance to belvarafenib in both a dimer- and a kinase activity-dependent manner. Belvarafenib induced ARAF mutant dimers, and dimers containing mutant ARAF were active in the presence of inhibitor. ARAF mutations may serve as a general resistance mechanism for RAF dimer inhibitors as the mutants exhibit reduced sensitivity to a panel of type II RAF inhibitors. The combination of RAF plus MEK inhibition may be used to delay ARAF-driven resistance and suggests a rational combination for clinical use. Together, our findings reveal specific and compensatory functions for the ARAF isoform and implicate ARAF mutations as a driver of resistance to RAF dimer inhibitors. ARAF mutations confer resistance to the RAF inhibitor belvarafenib in melanoma.,Yen I, Shanahan F, Lee J, Hong YS, Shin SJ, Moore AR, Sudhamsu J, Chang MT, Bae I, Dela Cruz D, Hunsaker T, Klijn C, Liau NPD, Lin E, Martin SE, Modrusan Z, Piskol R, Segal E, Venkatanarayan A, Ye X, Yin J, Zhang L, Kim JS, Lim HS, Kim KP, Kim YJ, Han HS, Lee SJ, Kim ST, Jung M, Hong YH, Noh YS, Choi M, Han O, Nowicka M, Srinivasan S, Yan Y, Kim TW, Malek S Nature. 2021 May 5. pii: 10.1038/s41586-021-03515-1. doi:, 10.1038/s41586-021-03515-1. PMID:33953400[13] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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