A Study of SY 5609, a Selective CDK7 Inhibitor, in Advanced Solid Tumors

Inclusion criteria

• Age ≥ 18 years
• Advanced Solid Tumors for which standard curative or palliative measures do not exist or are no longer effective (Group 1 only).
• Postmenopausal women with HR-positive, HER2-negative advanced or metastatic breast cancer. Participants must have failed prior treatment with a cyclin-dependent kinase (CDK) 4/6 inhibitor in combination with hormonal therapy in a previous line of therapy (Group 2 only).
• Participants with histologically or cytologically confirmed PDAC with measurable metastatic lesion(s) (Groups 3 and 4 only).
• Participants must have at least 1 measurable lesion by Response Evaluation Criteria in Solid Tumors (RECIST) v1.1.
• All toxicities (except alopecia) from prior cancer treatments must have resolved to ≤ Grade 1 before enrollment.
• For women of childbearing potential (WCBP): negative serum β human chorionic gonadotropin pregnancy test within 1 week before the first dose of SY 5609
• Adequate organ and marrow function
• Participants must be willing and able to comply with all aspects of the protocol
• Participants must provide written informed consent before any study-specific screening procedures.
• Albumin ≥ 3.0 grams/deciliters (g/dL) (Groups 3 and 4 only).

Exclusion criteria

• Chemotherapy or limited field radiotherapy within 2 weeks, wide field radiotherapy within 4 weeks, or nitrosoureas or mitomycin C within 6 weeks before entering the study
• Major surgery within 2 weeks before starting the study treatment, or not recovered to baseline status from the effects of surgery received > 2 weeks prior
• Received any other investigational agents within 4 weeks before enrollment, or < 5 half-lives since completion of previous investigational therapy, whichever is shorter
• Received previous noncytotoxic, US Food and Drug Administration-approved anticancer agent within previous 2 weeks, or < 5 half-lives since completion of previous therapy, whichever is shorter
• Known brain metastases or carcinomatous meningitis
• Immunocompromised participants with increased risk of opportunistic infections
• Participants with known active or chronic hepatitis B or active hepatitis C infection. Participants with a history of hepatitis C virus (HCV) infection who have completed curative therapy for HCV at least 12 weeks before Screening and have a documented undetectable viral load at Screening are eligible for enrollment.
• Baseline QT interval corrected (QTc) with Fridericia's method > 480 milliseconds

• NOTE: criterion does not apply to participants with a right or left bundle branch block (QTc interval)
• Female participants who are pregnant or breastfeeding
• History of clinically significant cardiac disease or clinically relevant uncontrolled cardiac risk factors
• Uncontrolled intercurrent illness.
• Poorly controlled ascites requiring paracentesis within 1 month prior to entering the study. (Groups 3 and 4 only)