This is a Phase I, multicenter, open-label, 3+3 dose escalation study to determine the safety and preliminary efficacy of PRJ1-3024 in subjects with relapsed/refractory solid tumors.

The study will evaluate the safety, tolerability, PK, and pharmacodynamics of PRJ1-3024 and will determine the maximum tolerated dose in subjects with advanced solid tumors.

PRJ1-3024 will be evaluated as an oral therapeutic that tests the anti-tumor activity of PRJ1-3024 in patients with solid tumors and has not yet been tested in humans.

This study will find the safe and tolerable recommended dose in subjects with advanced solid tumors as a open-label, 3+3 dose escalation study.

Key Inclusion Criteria:

• Histologically or cytologically confirmed locally advanced (unresectable) or metastatic r/r solid tumors for which no standard therapy is available or for whom standard therapy is considered unsuitable or intolerable.
• Male or non-pregnant, non-lactating female subjects age ≥18 years.
• ECOG Performance Status 0~2.
• Has at least 1 measurable lesion as defined by RECIST 1.1 criteria .
• Life expectancy of >3 months, in the opinion of the Investigator.
• Able to take oral medications and willing to record daily adherence to investigational product.
• Adequate hematologic parameters unless clearly due to the disease under study.
• Adequate renal and hepatic function
• Able to understand and willing to sign a written informed consent form.

Key Exclusion Criteria:

• History of another malignancy
• Known symptomatic brain metastases requiring >10 mg/day of prednisolone.
• Significant cardiovascular disease
• Known active HBV, HCV, AIDS-related illness.
• Has received a live vaccine within 30 days
• History of active autoimmune disorders or ongoing immunosuppressive therapy.
• Receiving concurrent anti-cancer therapy, investigational product, strong inhibitors or inducers of cytochrome P450 3A (CYP3A) .
• Prior treatment with hematopoietic progenitor kinase 1 (HPK1) inhibitors.