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Crystal structure of GMPPNP bound KRAS G12C in complex with CYPA and RMC-4791
Structural highlights
DiseaseRASK_HUMAN Defects in KRAS are a cause of acute myelogenous leukemia (AML) [MIM:601626. AML is a malignant disease in which hematopoietic precursors are arrested in an early stage of development.[1] Defects in KRAS are a cause of juvenile myelomonocytic leukemia (JMML) [MIM:607785. JMML is a pediatric myelodysplastic syndrome that constitutes approximately 30% of childhood cases of myelodysplastic syndrome (MDS) and 2% of leukemia. It is characterized by leukocytosis with tissue infiltration and in vitro hypersensitivity of myeloid progenitors to granulocyte-macrophage colony stimulating factor. Defects in KRAS are the cause of Noonan syndrome type 3 (NS3) [MIM:609942. Noonan syndrome (NS) [MIM:163950 is a disorder characterized by dysmorphic facial features, short stature, hypertelorism, cardiac anomalies, deafness, motor delay, and a bleeding diathesis. It is a genetically heterogeneous and relatively common syndrome, with an estimated incidence of 1 in 1000-2500 live births. Rarely, NS is associated with juvenile myelomonocytic leukemia (JMML). NS3 inheritance is autosomal dominant.[2] [3] [4] [5] [6] [7] Defects in KRAS are a cause of gastric cancer (GASC) [MIM:613659; also called gastric cancer intestinal or stomach cancer. Gastric cancer is a malignant disease which starts in the stomach, can spread to the esophagus or the small intestine, and can extend through the stomach wall to nearby lymph nodes and organs. It also can metastasize to other parts of the body. The term gastric cancer or gastric carcinoma refers to adenocarcinoma of the stomach that accounts for most of all gastric malignant tumors. Two main histologic types are recognized, diffuse type and intestinal type carcinomas. Diffuse tumors are poorly differentiated infiltrating lesions, resulting in thickening of the stomach. In contrast, intestinal tumors are usually exophytic, often ulcerating, and associated with intestinal metaplasia of the stomach, most often observed in sporadic disease.[8] [9] [10] Note=Defects in KRAS are a cause of pylocytic astrocytoma (PA). Pylocytic astrocytomas are neoplasms of the brain and spinal cord derived from glial cells which vary from histologically benign forms to highly anaplastic and malignant tumors.[11] Defects in KRAS 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. Note=KRAS mutations are involved in cancer development. FunctionRASK_HUMAN Ras proteins bind GDP/GTP and possess intrinsic GTPase activity. Publication Abstract from PubMedTri-complex inhibitors (TCIs) are molecular glues that bind the active, guanosine triphosphate (GTP)-bound state of RAS and recruit cyclophilin A (CYPA) to form a synthetic complex that blocks oncogenic signaling. Although these agents have shown clinical activity in RAS mutant cancers, resistance mechanisms remain poorly defined. Here, we analyzed paired baseline and end-of-treatment samples from 40 patients treated with the RAS inhibitor daraxonrasib and identified recurrent alterations in 18 cases. Structural and functional analyses revealed that acquired mutations confer resistance by disrupting interactions essential for daraxonrasib binding to RAS, including RAS Y64 mutations, or by enhancing the RAS-RAF interaction, thereby favoring native RAS-RAF signaling, including RAS Y71 or kinase-dead/hypoactive BRAF mutations. We then identified a TCI that targets RAS Y64 mutants and combination therapies to target resistance driven by kinase-dead BRAF. These findings uncover convergent resistance mechanisms that undermine the molecular glue function and offer a mechanistic blueprint for enhancing therapeutic efficacy in RAS-driven malignancies. Disrupted molecular glue complex drives RAS inhibitor resistance.,Sang B, Ye LF, Fu Z, Pourfarjam Y, Cuevas-Navarro A, Fan S, Hu F, Washington A, Rodriguez DJ, Vides A, Kar S, Ahler E, Lin KK, Hegde A, Smith JAM, Wolpin BM, Punekar SR, Spira AI, Garrido-Laguna I, Hong DS, Dar AC, Yaeger R, Arbour KC, Lito P Cell. 2026 May 14;189(10):2918-2933.e17. doi: 10.1016/j.cell.2026.03.031. Epub , 2026 May 5. PMID:42092352[12] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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