ILKN421H

This is a multicenter, open-label, phase II study to evaluate the safety, tolerability, clinical activity, and pharmacokinetics of ILKN421H in combination with pembrolizumab in participants with locally advanced or metastatic NSCLC. The study consists of 4 cohorts in participants with locally advanced or metastatic NSCLC ( squamous \[sq\] or non-squamous \[non-sq\]) without functional genomic alterations including EGFR, ALK and Ros-1, who failed systemic PD-1/L1 inhibitor treatment either alone or in combination with standard chemotherapy (post-IO) (Cohort 1 and 2), or without any prior systemic anti-cancer therapy (1L) with PDL-1 TPS ≥1% (Cohort 3 and 4). Participants will be dosed either with 1.6 mg of ILKN421H (Cohort 1 and Cohort 3) or 2.4 mg of ILKN421H (Cohort 2 and Cohort 4) in combination with 200 mg pembrolizumab. Both treatments will be administered through intravenous (i.v.) infusion every 3 weeks (Q3W) on Day 1 of each cycle with 21-day as one cycle, while ILKN421H will be dosed 4 hours after pembrolizumab. All 4 cohorts will have 3 study periods: * Screening Period: ≤ 28 days prior to first dose of study treatment; * Treatment period: 21-day cycles until unacceptable toxicity, lost to follow-up, disease progression, withdrawal of consent, death, or the sponsor closes the study, whichever occurs first; * Follow-up Period: 30-day safety follow-up and a Long-Term follow-up every 6-month for survival information.