A Study of Olomorasib (LY3537982) in Participants With Advanced Colorectal Cancer and a KRAS G12C Mutation

Inclusion Criteria: * Histologically or cytologically confirmed colorectal cancer (CRC) with Stage III or Stage IV disease, not suitable for curative intent radical surgery or radiation therapy. * Must have disease with evidence of KRAS G12C mutation * Have measurable disease per RECIST v1.1. * Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. * Ability to swallow capsules. * Have adequate laboratory parameters. * Have not received treatment for their CRC that has spread to other parts of the body. * 1-2 cycles of FOLFOX prior to study enrollment will be allowed for cases where immediate treatment is clinically indicated. Exclusion Criteria: * Have active inflammatory bowel disease requiring immunosuppressive medication or previous clear history of inflammatory bowel disease. * Have a clinically significant active malabsorption syndrome or other conditions likely to affect gastrointestinal absorption of the orally administered study treatments. * Have known untreated active central nervous system metastases or carcinomatous meningitis. * Have known additional malignancy that is progressing or has required treatment within the past 2 years. * Have uncontrolled, significant cardiovascular disease or cerebrovascular disease. * Have an active fungal, bacterial, or active, untreated viral infection. * Have human immunodeficiency virus (HIV) with a history of Kaposi's sarcoma or Multicentric Castleman's Disease. * Have known B-Raf proto-oncogene, serine/threonine kinase (BRAF) V600E gene mutation. * Have confirmed Microsatellite Instability-High/deficient Mismatch Repair (MSI-H/dMMR). * Individuals with known low or absent dihydropyrimidine dehydrogenase activity. * Have known positive Immunoglobulin E (IgE) antibodies against galactose-α-1,3-galactose (alpha-gal). * Have received adjuvant, neoadjuvant, concurrent chemoradiotherapy, or consolidation therapy if treatment was completed less than 6 months prior to enrollment. * Are pregnant, breastfeeding, or intend to become pregnant during the study.