Inclusion Criteria:
Phase 1a Dose-Escalation Cohorts:
1. Age 18 years or older with a pathologically confirmed, advanced, unresectable or metastatic solid tumor that is refractory to, or intolerant of, available existing therapy or therapies known to provide clinical benefit for the condition, if available, and with measurable disease.
Phase 1b Dose-Expansion Cohorts:
2. Age 18 years or older with a pathologically confirmed, advanced, unresectable or metastatic solid tumor that is refractory to, or intolerant of, available existing therapy or therapies known to provide clinical benefit for the condition, if available, or who has declined such therapy; presence of CCNE1 amplification; and measurable disease.
Common Eligibility Criteria:
3. Eastern Cooperative Oncology Group performance status of 0 or 1.
4. Adequate end-organ function, defined as creatinine clearance greater than 60 mL/min, aspartate aminotransferase and alanine aminotransferase less than 3 times the upper limit of normal, and total bilirubin less than 1.5 times the upper limit of normal, except for participants with Gilbert's disease.
5. Absolute neutrophil count at least 1.5 × 10\^9/L and platelet count at least 100 × 10\^9/L.
6. Female participants of childbearing potential must be willing to abstain from heterosexual intercourse or use a protocol-recommended method of contraception from screening throughout study treatment and for 90 days after the last dose of ZE94-0605.
7. Male participants of reproductive potential who have intercourse with females of childbearing potential must be willing to abstain from heterosexual intercourse or use a protocol-recommended method of contraception from the start of study treatment throughout study treatment and for 90 days after the last dose of ZE94-0605. Male participants must also refrain from sperm donation during this period.
8. Willingness to comply with scheduled visits, the drug-administration plan, imaging studies, laboratory tests, other study procedures, and study restrictions.
Exclusion Criteria:
1. History of another malignancy, except adequately treated local basal cell carcinoma or squamous cell carcinoma of the skin, cervical carcinoma in situ, superficial bladder cancer, asymptomatic prostate cancer without known metastatic disease, or another cancer that has been in complete remission without treatment for at least 2 years before enrollment or has a life expectancy of 24 months and does not require therapy that would confound interpretation of this study. Such cases must be discussed with the Medical Monitor before screening.
2. Known active hepatitis C, hepatitis B, or human immunodeficiency virus infection.
3. Pregnancy or breastfeeding.
4. Concurrent participation in an investigational-drug trial with therapeutic intent, defined as receipt of prior study therapy within 14 days before study treatment.
5. Inability to tolerate oral medication, including symptomatic disease that significantly affects gastrointestinal function, such as inflammatory bowel disease or resection of the stomach or small bowel.
6. Receipt of an investigational agent for any indication within 5 half-lives of the agent. If the half-life is unknown, the participant must wait 1 week before the first dose of study treatment. An investigational agent is one for which there is no approved indication from the U.S. Food and Drug Administration.
7. Psychological, familial, social, or geographic factors; another significant medical condition; or a laboratory abnormality that precludes informed consent or protocol compliance, may hamper adherence to study treatment or follow-up, or would confound interpretation of study results.
8. Uncontrolled intercurrent illness, including but not limited to symptomatic congestive heart failure, unstable angina pectoris, serious cardiac arrhythmia, New York Heart Association Class III or IV heart failure, severe uncontrolled ventricular arrhythmias, or electrocardiographic evidence of acute ischemia or active conduction-system abnormalities. Participants with medical comorbidities that would preclude safety evaluation of ZE94-0605 must not be enrolled.
9. QT interval corrected using Fridericia's formula (QTcF) greater than or equal to 470 milliseconds, unless the participant has a pacemaker. Participants with an incomplete or complete right or left bundle branch block may participate if cleared for enrollment by a cardiology evaluation.
