The safety, pharmacokinetics, and efficacy of HA121-28 were assessed in advanced solid tumors (phase 1, ClinicalTrials.gov NCT03994484) and advanced RET fusion-positive non-small-cell lung cancer (RET-TKI naive NSCLC, phase 2, ClinicalTrials.gov NCT05117658). The gene discussed is RET; the disease is non-small cell lung carcinoma.