A Study of [225Ac]Ac-AKY-2519 in Patients With B7-H3 Expressing Solid Tumors

This is a Phase 1b, 2-part, multi-center, open-label study to evaluate the safety, tolerability, dosimetry, and pharmacokinetics (PK) of \[64Cu\]Cu-AKY-2519 and/or \[225Ac\]Ac-AKY-2519, as well as the preliminary anti-tumor activity of \[225Ac\]Ac-AKY-2519 in participants with B7-H3 imaging positive solid tumors.

Inclusion Criteria: * Age ≥ 18 years * Histologic or cytologic confirmation of locally advanced or metastatic NSCLC, ES-SCLC, HNSCC, ESCC, CRC or prostatic adenocarcinoma * Radiologic confirmation on CT of at least one measurable tumor lesion per RECIST v1.1 * ECOG Performance Status of 0 or 1 * Adequate end-organ function * Ability to give informed consent and comply with study requirements * Patients with CNS metastases are eligible if they have received therapy and are neurologically stable, asymptomatic and not receiving corticosteroids Exclusion Criteria: * Prior treatment with a B7-H3 targeted therapy * Prior treatment with a targeted radiotherapy * Received an investigational agent within the previous 28 days * Prior treatment with a cytotoxic chemotherapy, targeted therapy, biologic agent, immunotherapy or external-beam radiotherapy within the previous 28 days * Impaired cardiac function or clinically significant cardiac disease * Concurrent serious medical condition that would impair study participation or impact the assessment of treatment related toxicity