A Study to Investigate the Safety and Efficacy of KQB198 as Monotherapy and in Combination in Participants With Advanced Solid Malignancies

Inclusion Criteria: * PART 1 - Histologically confirmed diagnosis of a solid tumor malignancy with any of the following oncogenic mutations: EGFR, RAS, PTPN11, or SOS1 mutations, or inactivating mutations of NF1. * PART 1 - (Osimertinib and Amivantamab arms) and Part 2 Cohort A and Cohort B: Histologically confirmed diagnosis of NSCLC with activating EGFR mutation and progression on osimertinib * Part 3 - Cohort A: Histologically confirmed diagnosis of NSCLC with exon 20 insertion EGFR mutation * Unresectable or metastatic disease * No available treatment with curative intent * Adequate organ function * Measurable disease per RECIST 1.1. Exclusion Criteria: * Prior therapy with a similar mechanism of action to KQB198 * History of intestinal disease, inflammatory bowel disease, major gastric surgery, or other gastrointestinal conditions likely to alter absorption of study treatment or result in inability to swallow * History of interstitial lung disease * Cardiac abnormalities