Supplementary Table S1 details the efficacy of MRTX0902 in a panel of cancer cell lines.

Supplementary Table S2 shows the antitumor activity of MRTX0902 and adagrasib in a panel of human KRAS G12C-mutant tumor cell line-derived and patient-derived xenograft models.

Supplementary Table S5 details the antitumor activity of MRTX0902 and avutometinib in human KRAS-MAPK pathway mutant tumor cell line-derived xenograft models.

Supplementary Figure S4 shows levels of KRAS-MAPK pathway modulation associated with coadministration of MRTX0902 and adagrasib in the MIA PaCa-2 (KRAS G12C-mutant) model.

Supplementary Figure S6 details the improved antiproliferative activity observed with the MRTX0902/osimertinib combination in EGFR mutant models, PC9 (EGFR ex19del) and NCI-H1975 (EGFR L858R/T790M).

Supplementary Figure S5 shows levels of KRAS-MAPK pathway modulation associated with coadministration of MRTX0902 and adagrasib in the murine CT26 (KRAS G12C-mutant) model.

Supplementary Figure S3 details the antitumor effects and gene set enrichment analysis data associated with coadministration of MRTX0902 and adagrasib in KRAS G12C-mutant human tumor xenograft models.

Supplementary Materials and Methods section includes detailed protocols for the following: Experimental Preparation of MRTX0902 and Avutometinib, SOS1 Biochemical Binding Assay, SOS1 and SOS2 Functional Assays, KRAS-SOS1 Protein-Protiein Interaction (PPI) HTRF Assay, In-Cell Western Assay, 3D Ultra-Low Attachment (ULA) Viability Assay, Immunoblotting and Densitometry Analysis, DUSP6 Quantification from Naive and Tumor-Bearing Mouse Blood, Bioanalysis and Pharmacokinetic Analysis, Synergy Analysis, CRISPR/Cas9 Screening and Data Analysis Methodology, RNAseq Pre-Processing, RNAseq Data Analysis, and Whole Genome Sequencing.

Supplementary Table S3 displays the various genetic co-alterations present in human KRAS G12C-mutant tumor cell line-derived and patient-derived xenograft models evaluated.

Supplementary Figure S7 shows the improved antiproliferative activity observed with the MRTX0902/avutometinib combination in KRAS-MAPK pathway mutant models, LN229 (PTPN11 A72S) and NCI-H1435 (NF1 K615N).

Supplementary Figure S8 details the antitumor effects associated with coadministration of MRTX0902 and adagrasib in the MIA PaCa-2 (KRAS G12C-mutant) model.

Supplementary Figure S2 shows the antitumor activity of MRTX0902 in the LN229 (PTPN11 A72S-mutant) model, with tumor growth inhibition data displayed in Figure S2A and ERK phosphorylation graphed in Figure S2B.

Supplementary Figure S1 details the genetic vulnerabilities and modifiers of response associated with combination treatment of MRTX0902 with adagrasib in the KRAS G12C-mutant MIA PaCa-2 (S1A, S1B, S1D, and S1E) and LU99 (S1C) cell lines in vitro and in vivo.

Supplementary Table S4 shows the antitumor activity of MRTX0902 and osimertinib in human EGFR-mutant tumor cell line-derived xenograft models.

KRAS mutations are prevalent in brain metastases (BM) from non-small cell lung cancer (NSCLC). The activity of KRAS-G12C selective, brain-penetrant small molecule inhibitor adagrasib was recently demonstrated in preclinical models of BM and patients with BM carrying KRAS-G12C, leading to a clinical trial investigating this therapeutic approach. However, co-existing genomic drivers such as homozygous deletion of CDKN2A/B may impact the utility of adagrasib. We therefore explored the combination therapy employing adagrasib and abemaciclib, a brain-penetrant CDK4/6 inhibitor, in NSCLC BM models driven by KRAS-G12C and CDKN2A loss. In both adagrasib-resistant SW1573 cells and adagrasib-responsive H2122 cells, combination of adagrasib and abemaciclib was slightly synergistic in inhibiting cell viability in vitro through targeting the KRAS-ERK and CDK4/6-Rb signaling pathways. Combination treatment was necessary to activate caspase 3/7-mediated apoptosis in SW1573 cells, while adagrasib alone and in combination comparably elicited apoptosis in H2122 cells. In vivo, combination treatment with adagrasib (75 mg/kg) twice daily and abemaciclib (50 mg/kg) daily was associated with body weight loss (about 10%) in mice bearing orthotopic BM derived with SW1573 or H2122 cells, requiring 50% dose reduction of adagrasib in some animals. Notably, combination treatment, but neither monotherapy, extended animal survival in the SW1573 model. On the other hand, adagrasib monotherapy and combination were similarly effective at prolonging survival, while abemaciclib monotherapy was ineffective in the H2122 model. Pharmacokinetic studies confirmed brain-penetrant properties of both agents and revealed drug-drug interactions as abemaciclib exposures in the plasma and brains were increased by the presence of adagrasib. Immunohistochemistry demonstrated on-target pharmacodynamic effects of both agents in BM in mice. Our work thus supports that the combination treatment of adagrasib and abemaciclib can offer a therapeutic strategy in NSCLC BM genomically characterized by KRAS-G12C and CDKN2A loss.

This study investigated absorption, metabolism, and excretion of adagrasib after a single oral 600 mg dose (1 µCi [14C]-adagrasib) in 7 healthy subjects and compared the metabolite profile to the profile at steady-state in 4 patients dosed at 600 mg twice daily. Plasma, urine, and feces were collected post [14C]-adagrasib administration and total radioactivity and pooled sample metabolite profiles were determined. Adagrasib pharmacokinetics were determined in plasma and urine. The steady-state plasma metabolite profile was examined in patients and in vitro studies were performed to understand adagrasib’s potential to inhibit CYP enzymes and identify CYPs involved in its metabolism. The total mean recovery of the administered radioactivity was 79.2

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. MRTX0902 augmented the antitumor activity of the KRAS G12C inhibitor adagrasib when dosed in combination in eight out of 12 KRAS G12C-mutant human non-small cell lung cancer and colorectal cancer xenograft models. Pharmacogenomic profiling in preclinical models identified cell cycle genes and the SOS2 homolog as genetic co-dependencies and implicated tumor suppressor genes (NF1 and PTEN) in resistance following combination treatment. Lastly, combined vertical inhibition of RTK/MAPK pathway signaling by MRTX0902 with inhibitors of EGFR or RAF/MEK led to greater downregulation of pathway signaling and improved antitumor responses in KRAS-MAPK pathway-mutant models. These studies demonstrate the potential clinical application of dual inhibition of SOS1 and KRAS G12C and additional SOS1 combination strategies that will aide in the understanding of SOS1 and RTK/MAPK biology in targeted cancer therapy.

The H1047R mutation of PIK3CA is highly prevalent in breast cancers and other solid tumors. Selectively targeting PI3KαH1047R over PI3KαWT is crucial due to the role that PI3KαWT plays in normal cellular processes, including glucose homeostasis. Currently, only one PI3KαH1047R-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. Herein, we report the design and discovery of a series of pyridopyrimidinones that inhibit PI3KαH1047R with high selectivity over PI3KαWT, resulting in the discovery of compound 17. When dosed in the HCC1954 tumor model in mice, 17 provided tumor regressions and a clear pharmacodynamic response. X-ray cocrystal structures from several PI3Kα inhibitors were obtained, revealing three distinct binding modes within PI3KαH1047R including a previously reported cryptic pocket in the C-terminus of the kinase domain wherein we observe a ligand-induced interaction with Arg1047.

Adagrasib is a potent, highly selective, orally available, small molecule, covalent inhibitor of G12C mutated KRAS. As both a substrate and strong inhibitor of cytochrome P450 (CYP) 3A4, adagrasib inhibits its own CYP3A4-mediated metabolism following multiple dosing, resulting in time-dependent drug-drug interaction (DDI) liabilities. A physiologically-based pharmacokinetic (PBPK) model was developed and verified using a combination of physicochemical, in vitro and clinical pharmacokinetic (PK) data from healthy volunteers and cancer patients. The PBPK model well-described the single and multiple-dose adagrasib PK data as well as DDI data with itraconazole, rifampin, midazolam, warfarin, dextromethorphan, and digoxin, with model predictions within 1.5-fold of the observed clinical data. The PBPK model was used to predict untested scenarios including the clinical victim and perpetrator DDI liabilities at the approved dosing regimen of 600 mg twice daily (b.i.d.) in cancer patients. Strong, moderate, and weak inhibitors of CYP3A4 are predicted to have a negligible effect on the steady-state exposure of adagrasib 600 mg b.i.d. resulting from the significant inactivation of CYP3A4 by adagrasib. Additionally, strong and moderate inducers of CYP3A4 are predicted to decrease adagrasib exposure by 68% and 22%, respectively. As a perpetrator, adagrasib 600 mg b.i.d. is predicted to be a strong inhibitor of CYP3A4, a moderate inhibitor of CYP2C9 and CYP2D6, and an inhibitor of P-glycoprotein (P-gp). These results successfully supported regulatory interactions with the United States Food and Drug Administration regarding dosing recommendations for when adagrasib is used concomitantly with other medications, supporting a range of label claims in lieu of clinical trials.

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:KRASG12C protein-protein interaction (PPI) can increase the proportion of GDP-loaded KRASG12C, providing a strong mechanistic rationale for combining inhibitors of the SOS1:KRAS complex with inhibitors like MRTX849 that target GDP-loaded KRASG12C. 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:KRASG12C PPI. Oral administration of MRTX0902 in combination with MRTX849 results in a significant increase in antitumor activity relative to that of either single agent, including tumor regressions in a subset of animals in the MIA PaCa-2 tumor mouse xenograft model.