Inclusion Criteria:
* Ability to provide written informed consent prior to any study-related procedures and to understand the nature, purpose, and potential risks of the study
* Adult males and females ≥18 years of age at screening
* Life expectancy of at least 3 months
* Histologically or cytologically confirmed unresectable advanced solid tumor (recurrent, metastatic, or locally advanced)
* Disease refractory to, intolerant of, or refusal of standard therapies, including immunotherapy and molecular/biomarker-directed treatments, as determined by the Principal Investigator (PI) or delegate
* Eligible tumor types include:
* Head and neck squamous cell carcinoma
* Thoracic malignancies (small-cell lung cancer, non-small cell lung cancer, esophageal cancer)
* Gastrointestinal malignancies (gastric, liver, colorectal, pancreatic adenocarcinoma)
* Genitourinary malignancies (bladder, renal cell, prostate cancer)
* Gynecologic malignancies (ovarian, endometrial cancer)
* Breast cancer and melanoma
* Evaluable disease per RECIST v1.1
* ECOG performance status 0-1 (or up to 2 at PI discretion)
* Adequate organ function, defined as:
* Total bilirubin ≤1.5 × ULN (≤2.0 × ULN for liver metastases or Gilbert's syndrome)
* AST, ALT, alkaline phosphatase ≤2.5 × ULN (≤5 × ULN if liver metastases, at PI discretion)
* Creatinine clearance ≥50 mL/min (Cockcroft-Gault) or eGFR ≥50 mL/min (CKD-EPI)
* Absolute neutrophil count ≥1,000/mm³
* Platelet count ≥100,000/mm³
* Hemoglobin ≥90 g/L without transfusion within 2 weeks
* Prothrombin time and aPTT ≤1.5 × ULN (or stable INR if on anticoagulation)
Female patients:
-Non-childbearing potential (surgically sterile or postmenopausal), or of childbearing potential with negative pregnancy tests and agreement to effective contraception through 90 days post-dose
Male patients:
* Agreement not to donate sperm for 90 days post-dose
* Agreement to use adequate contraception as applicable
* Suitable venous access for blood sampling
* Willingness and ability to comply with study procedures and protocol requirements
Exclusion Criteria:
* Ongoing toxicities ≥ Grade 2 per NCI CTCAE v5.0 (except alopecia, fatigue, sensory neuropathy, or adequately treated endocrine deficiencies)
* NYHA Class III or IV heart disease, myocardial infarction within 6 months, unstable arrhythmia, or ischemia on ECG
* QTcF \>470 ms (females) or \>450 ms (males)
* Active, uncontrolled bacterial, viral, or fungal infection requiring systemic therapy
* Requirement for systemic corticosteroids or other immunosuppressive therapy that cannot be discontinued ≥14 days prior to dosing
* Prior therapies within restricted timeframes:
* Immune checkpoint inhibitors or biologics within 28 days
* Antineoplastic therapies, surgery, radiotherapy, or radiopharmaceuticals within 21 days
* Unapproved investigational drugs within 5 half-lives
* Nitrosoureas or mitomycin C within 6 weeks
* Concurrent malignancy within 5 years, except specified low-risk cancers
* Pregnancy or breastfeeding
* Known HIV, hepatitis B (HBsAg positive), or hepatitis C infection
* Inability or unwillingness to comply with protocol procedures
* History of anaphylaxis or significant allergy interfering with participation
* Clinically significant cardiovascular, pulmonary, hepatic, renal, hematologic, gastrointestinal, endocrine, neurologic, psychiatric, or immunologic disease within 6 months
* Conditions affecting drug absorption, distribution, metabolism, or excretion
* Receipt of live vaccines within 28 days prior to screening
* Participation in another investigational study within 30 days prior to screening
