Background: Mutations in KRAS are among the most frequent oncogenic drivers with the G12C variant found in ~13% of NSCLC. Outcomes for KRAS G12C-mutant NSCLC may be improved by combining KRAS G12C inhibitors with current 1L standard of care (SOC). Olomorasib is a potent and highly selective second-generation inhibitor of KRAS G12C, which delivers >90% sustained target occupancy in preclinical models. In the LOXO-RAS-20001 phase 1/2 study, olomorasib in combination with pembrolizumab demonstrated preliminary efficacy and a favorable safety profile.¹Methods: SUNRAY-01 (NCT06119581) is a pivotal, global, phase 3 study in 1L advanced KRAS G12C-mutated NSCLC designed to seamlessly 1) optimize the dosing of olomorasib in combination with 1L SOC, and then 2) compare efficacy and safety of olomorasib plus SOC with placebo plus SOC. In the open-label randomized dose optimization (pembrolizumab plus olomorasib 50 mg vs 100 mg BID) and single arm safety lead-in (olomorasib plus pembrolizumab, pemetrexed, platinum), the optimal dose of olomorasib for combination therapy will be determined before the phase 3 study (parts A and B) is opened for enrollment. In part A, 384 participants with PD-L1 expression ≥50% are randomized (1:1) to pembrolizumab plus olomorasib or placebo. In part B, 552 participants are randomized (1:1) to pembrolizumab, pemetrexed, platinum plus olomorasib or placebo regardless of PD-L1 expression. Allocation of participants with PD-L1 expression ≥50% to either part A or part B will be at the discretion of the investigator. The primary objective is to compare efficacy based on PFS per RECIST v1.1 by blinded independent central review. Secondary endpoints include OS, ORR, DOR, DCR, TTR, PFS2, safety and tolerability, and patient-reported outcomes. Eligible participants (≥18 years) must have a KRAS G12C mutation in tumor or blood and known PD-L1 expression (0-100%), stage IIIB, IIIC, or IV NSCLC not suitable for curative intent radical surgery or radiation therapy, measurable disease per RECIST v1.1, and an ECOG PS 0-1. Participants can be enrolled based on local KRAS and PD-L1 testing results. Participants should not have received prior systemic therapy for advanced or metastatic NSCLC, however 1 cycle of SOC treatment prior to enrollment is allowed if immediate treatment is clinically indicated. Participants with asymptomatic (lesions ≤1.5 cm) or previously treated radiographically stable brain metastases are eligible. Key exclusion criteria include history of pneumonitis/interstitial lung disease and clinically significant active cardiovascular disease or malabsorption syndrome. The study opened for enrollment in December 2023. Reference: 1. Murciano-Goroff et al. 2023 Cancer Res 83 (8 Suppl): CT028. Clinical trial information: NCT06119581.