This study investigates the safety and tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of EIK1003 in participants with advanced solid tumors.

This study will evaluate the safety, tolerability and preliminary efficacy of IMP1734 as monotherapy in patients with recurrent, advanced/metastatic solid tumors. This study includes 2 parts: Part 1 and Part 2. Part 1 includes a monotherapy dose escalation of EIK1003 followed by combination dose escalations in metastatic prostate cancer (mPC), ovarian and breast cancer.

Part 1, dose escalation, the study will identify the maximum tolerated dose (MTD) or maximum achievable dose (MAD) in solid tumor.

Part 2 will explore dose optimization with selection of an optimal dose for future clinical development of EIK1003.

Key Inclusion Criteria

• Breast cancer; must have received at least one prior chemotherapy in neoadjuvant/adjuvant/metastatic setting, must have received hormonal therapy if HR+,
• HGSOC or high grade endometrioid EOC, fallopian tube or primary peritoneal cancer; must have received at least one prior platinum-based chemotherapy for advanced disease
• mCRPC with ongoing ADT, must have received NHA and up to 1 prior line of taxane chemotherapy
• Age ≥ 18 years at the time of informed consent
• Eastern Cooperative Oncology Group (ECOG) performance status ≤1
• Adequate organ function
• Life expectancy ≥ 12 weeks
• Should have evaluable disease as defined by RECIST1.1 and/or CA125 or PSA
• Female subjects of childbearing potential and male subjects must agree to use an effective method of contraception from study entry up to 6 months after the last dose of IMP1734
• deleterious or suspected deleterious germline or somatic mutations of select HRR genes
• up to 1 prior line of PARP inhibitor containing treatment

Key Exclusion Criteria:

• Any investigational or approved anti-cancer therapies administered within 28 days/ before the first dose of IMP1734

• Have received prior PARP1 selective inhibitors

• Mean resting QTcF > 470 ms or QTcF < 340 ms

• Active or untreated central nervous system (CNS) metastases and/or carcinomatous meningitis.

• Infections

  - An active hepatitis B/C infection

• Any known predisposition to bleeding

• Unable to swallow oral medications OR have malabsorption syndrome or any other uncontrolled gastrointestinal condition that might impair the bioavailability