A Study to Investigate the Safety and Efficacy of KQB365 as Monotherapy and in Combination in Participants With Advanced Solid Malignancies

Inclusion Criteria: * PART 1 (monotherapy and combo therapy with KQB198): Histologically confirmed diagnosis of a solid tumor malignancy with either a KRAS G12C or KRAS G12S mutation. * PART 1 (combo therapy with Cetuximab) \& PART 2: Histologically confirmed diagnosis of adenocarcinoma of the colon or rectum with either a KRAS G12C or KRAS G12S mutation. * Unresectable or metastatic disease * No available treatment with curative intent * Adequate organ function * Measurable disease per RECIST v1.1 Exclusion Criteria: * Active primary central nervous system tumors * Cardiac abnormalities * Active interstitial lung disease * Unable to swallow or GI condition that prevents absorption for patients in KQB198 combination cohorts