Background: Kirsten rat sarcoma (KRAS) G12D is a point mutation observed in various cancer types including pancreatic ductal cancer, colon adenocarcinoma, and lung cancers. ASP3082 is a novel small-molecule proteolysis-targeting chimeric degrader that binds to, and selectively targets, the KRAS G12D-mutated protein for degradation via recruitment of E3 ubiquitin ligase proteins. In preclinical studies, ASP3082 selectively degraded the KRAS G12D-mutated protein and showed growth inhibitory activity in KRAS G12D-mutated cancer cells but not in KRAS-wildtype cancer cells. Notable antitumor effects of ASP3082 have been demonstrated when intravenously administered weekly in mice xenografted with KRAS G12D-mutated cancer cells. Methods: This first-in-human, open-label, multicenter, phase 1 study evaluates the safety and tolerability of ASP3082 in patients with pancreatic cancer, colorectal cancer, non-small cell lung cancer or other solid tumors. Participants with unresectable, locally advanced, or metastatic solid tumor malignancy with documented KRAS G12D mutation are eligible for enrollment. Part 1 consists of dose-escalation cohorts of 3−12 patients receiving intravenous administration of ASP3082 in a 21-day cycle. Part 2 consists of random assignment of ≤20 patients into 2 cohorts with different ASP3082 dose levels to determine the recommended phase 2 dose. Additional tumor-specific expansion cohorts may enroll ≤20 participants per tumor type. Primary endpoints will evaluate safety and tolerability as noted by dose-limiting toxicities, adverse events, serious adverse events, laboratory test results, electrocardiograms, vital signs, physical exams, and Eastern Cooperative Oncology Group performance status. Secondary endpoints will evaluate objective response rate, duration of response, disease control rate per Response Evaluation Criteria in Solid Tumors version 1.1, pharmacokinetics of single and repeated doses of ASP3082, and changes in KRAS G12D in tumor samples. Exploratory objectives will evaluate potential biomarkers that may correlate with treatment outcomes. Tumor assessment follow-up will continue for ≤45 weeks or until progressive disease. Enrollment in Cohort 1 is complete, and enrollment to Cohort 2 began in September 2022. Clinical trial information: NCT05382559.