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 ofthe following oncogenic mutations: EGFR, RAS, PTPN11, or SOS1 mutations, orinactivating mutations of NF1.

• PART 1 (Osimertinib arm) and Part 2 Cohort A: Histologically confirmed diagnosis ofNSCLC with activating EGFR mutation and progression on osimertinib

• Part 3 Cohort A: Histologically confirmed diagnosis of NSCLC with exon 20 insertionEGFR 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, orother gastrointestinal conditions likely to alter absorption of study treatment orresult in inability to swallow

• History of interstitial lung disease

• Cardiac abnormalities