This phase I trial is trying to understand how safe and effective a targeted therapy (HP518) is in people with prostate cancer.A Phase 1 Open-Label Study to Assess the Safety, Pharmacokinetics, and Anti-tumor Activity of Oral HP518 in Patients With Metastatic Castration-Resistant Prostate Cancer

Exclusion

1. Has received more than 1 line of chemotherapy for prostate cancer.

2. Use of enzalutamide, and/or other second-generation AR inhibitors and/or abiraterone as follows:

   • Received any agent within 4 weeks prior to the start of study drug.
   • Discontinued agent without evidence of radiographic or PSA progression.
3. Has had any anticancer treatments, including immunotherapy, chemotherapy, or radiotherapy (eg, 177Lu-PSMA-617, radium 223, PARP inhibitor) within 4 weeks prior to the first dose of HP518.
4. Has gastrointestinal disorder affecting absorption (e.g., gastrectomy).
5. Has significant cardiovascular disease.
6. Use of an investigational agent, without evidence of radiographic or PSA progression, within 4 weeks prior to the first dose of HP518 or a period required by local regulation, whichever is longer.