The SOS1 Inhibitor MRTX0902 Blocks KRAS Activation and Demonstrates Antitumor Activity in Cancers Dependent on KRAS Nucleotide Loading.

KRAS is the most frequently mutated oncogene in human cancer and facilitates uncontrolled growth through hyperactivation of the receptor tyrosine kinase (RTK)/mitogen-activated protein kinase (MAPK) pathway. The Son of Sevenless homolog 1 (SOS1) protein functions as a guanine nucleotide exchange factor (GEF) for the RAS subfamily of small GTPases and represents a druggable target in the pathway. Using a structure-based drug discovery approach, MRTX0902 was identified as a selective and potent SOS1 inhibitor that disrupts the KRAS:SOS1 protein-protein interaction to prevent SOS1-mediated nucleotide exchange on KRAS and translates into an anti-proliferative effect in cancer cell lines with genetic alterations of the KRAS-MAPK pathway.

Discovery of Pyridopyrimidinones that Selectively Inhibit the H1047R PI3Kα Mutant Protein.

The H1047R mutation of is highly prevalent in breast cancers and other solid tumors. Selectively targeting PI3Kα over PI3Kα is crucial due to the role that PI3Kα plays in normal cellular processes, including glucose homeostasis. Currently, only one PI3Kα-selective inhibitor has progressed into clinical trials, while three pan mutant (H1047R, H1047L, H1047Y, E542K, and E545K) selective PI3Kα inhibitors have also reached the clinical stage.

Anti-tumor efficacy of a potent and selective non-covalent KRAS inhibitor.

Recent progress in targeting KRAS has provided both insight and inspiration for targeting alternative KRAS mutants. In this study, we evaluated the mechanism of action and anti-tumor efficacy of MRTX1133, a potent, selective and non-covalent KRAS inhibitor. MRTX1133 demonstrated a high-affinity interaction with GDP-loaded KRAS with K and IC values of ~0.

Design and Discovery of MRTX0902, a Potent, Selective, Brain-Penetrant, and Orally Bioavailable Inhibitor of the SOS1:KRAS Protein-Protein Interaction.

SOS1 is one of the major guanine nucleotide exchange factors that regulates the ability of KRAS to cycle through its "on" and "off" states. Disrupting the SOS1:KRAS protein-protein interaction (PPI) can increase the proportion of GDP-loaded KRAS, providing a strong mechanistic rationale for combining inhibitors of the SOS1:KRAS complex with inhibitors like MRTX849 that target GDP-loaded KRAS. In this report, we detail the design and discovery of MRTX0902─a potent, selective, brain-penetrant, and orally bioavailable SOS1 binder that disrupts the SOS1:KRAS PPI.

Fragment-Based Discovery of MRTX1719, a Synthetic Lethal Inhibitor of the PRMT5•MTA Complex for the Treatment of -Deleted Cancers.

The PRMT5•MTA complex has recently emerged as a new synthetically lethal drug target for the treatment of -deleted cancers. Here, we report the discovery of development candidate . is a potent and selective binder to the PRMT5•MTA complex and selectively inhibits PRMT5 activity in -deleted cells compared to -wild-type cells.

Identification of MRTX1133, a Noncovalent, Potent, and Selective KRAS Inhibitor.

KRAS, the most common oncogenic KRAS mutation, is a promising target for the treatment of solid tumors. However, when compared to KRAS, selective inhibition of KRAS presents a significant challenge due to the requirement of inhibitors to bind KRAS with high enough affinity to obviate the need for covalent interactions with the mutant KRAS protein. Here, we report the discovery and characterization of the first noncovalent, potent, and selective KRAS inhibitor, MRTX1133, which was discovered through an extensive structure-based activity improvement and shown to be efficacious in a KRAS mutant xenograft mouse tumor model.

The KRAS Inhibitor MRTX849 Reconditions the Tumor Immune Microenvironment and Sensitizes Tumors to Checkpoint Inhibitor Therapy.

KRAS inhibitors, including MRTX849, are promising treatment options for KRAS-mutant non-small cell lung cancer (NSCLC). PD-1 inhibitors are approved in NSCLC; however, strategies to enhance checkpoint inhibitor therapy (CIT) are needed. mutations are smoking-associated transversion mutations associated with high tumor mutation burden, PD-L1 positivity, and an immunosuppressive tumor microenvironment.

Identification of the Clinical Development Candidate , a Covalent KRAS Inhibitor for the Treatment of Cancer.

Capping off an era marred by drug development failures and punctuated by waning interest and presumed intractability toward direct targeting of KRAS, new technologies and strategies are aiding in the target's resurgence. As previously reported, the tetrahydropyridopyrimidines were identified as irreversible covalent inhibitors of KRAS that bind in the switch-II pocket of KRAS and make a covalent bond to cysteine 12. Using structure-based drug design in conjunction with a focused in vitro absorption, distribution, metabolism and excretion screening approach, analogues were synthesized to increase the potency and reduce metabolic liabilities of this series.

The KRAS Inhibitor MRTX849 Provides Insight toward Therapeutic Susceptibility of KRAS-Mutant Cancers in Mouse Models and Patients.

Despite decades of research, efforts to directly target KRAS have been challenging. MRTX849 was identified as a potent, selective, and covalent KRAS inhibitor that exhibits favorable drug-like properties, selectively modifies mutant cysteine 12 in GDP-bound KRAS, and inhibits KRAS-dependent signaling. MRTX849 demonstrated pronounced tumor regression in 17 of 26 (65%) KRAS-positive cell line- and patient-derived xenograft models from multiple tumor types, and objective responses have been observed in patients with KRAS-positive lung and colon adenocarcinomas.

Discovery of Tetrahydropyridopyrimidines as Irreversible Covalent Inhibitors of KRAS-G12C with In Vivo Activity.

is the most frequently mutated driver oncogene in human cancer, and KRAS mutations are commonly associated with poor prognosis and resistance to standard treatment. The ability to effectively target and block the function of mutated KRAS has remained elusive despite decades of research. Recent findings have demonstrated that directly targeting KRAS-G12C with electrophilic small molecules that covalently modify the mutated codon 12 cysteine is feasible.