This is an open-label, multi-center, Phase 1 study designed to evaluate the safety, tolerability, pharmacokinetics, and efficacy of BBO-8520, a direct inhibitor of KRASG12C (ON and OFF), alone and in combination with the ICI pembrolizumab and BBO-10203 in subjects with locally advanced and unresectable or metastatic non-small cell lung cancer with a KRAS (Kirsten rat sarcoma) G12C mutation. The study includes dose escalation phase and dose expansion phase