A Study of PEP07 (Checkpoint Kinase 1 Inhibitor) in Patients with Advanced or Metastatic Solid Tumors

Inclusion Criteria: 1\. Subjects must be ≥ 20 years of age 2a. For subject in the dose escalation stage: Subjects with advanced or metastatic solid tumors who have failed on or are intolerant to standard treatment or have no access to standard treatment. 2b. For subject in the dose expansion stage: Subjects with histologically or cytologically confirmed malignant solid tumors which are advanced or metastatic, who have failed on or are intolerant to standard treatment or have no access to standard treatment. 3\. At least one measurable lesion according to the RECIST version 1.1. 4\. Subjects must have ECOG Performance score of 0-1. 5\. Subject must have adequate renal function as demonstrated by a calculated creatinine clearance ≥ 50 mL/min; determined via urine collection for 24-hour creatinine clearance or by the Cockcroft Gault formula. 6\. Subject must have adequate liver function as demonstrated by: * Aspartate aminotransferase (AST) ≤ 2.5 × ULN (≤ 5 × ULN, if attributable to liver metastases) * Alanine aminotransferase (ALT) ≤ 2.5 × ULN (≤ 5 × ULN, if attributable to liver metastases) * Bilirubin ≤ 1.5 × ULN 7\. Subject must have adequate bone marrow function as demonstrated by: * Absolute neutrophil count (ANC) ≥ 1500/mm3 * Platelet counts ≥ 100,000/mm3 * Hemoglobin ≥ 9 g/dL 8\. Female subjects with reproductive potential must have a negative serum pregnancy test within 7 days prior to the first dose of study treatment. Women of childbearing potential as well as males of reproductive potential must agree to refrain from unprotected sex and ensure highly effective contraception with partner during study period and until 6 months after the last dose of study drug. 9\. Provision of signed and dated informed consent form. Exclusion Criteria: 1. Pregnant or breastfeeding females. 2. Subjects have received anti-cancer therapy including chemotherapy, radiotherapy, hormonal or any investigational therapy within 14 days or 5 half-lives (whichever is shorter) or immunotherapy within 30 days prior to the first dose of study treatment. 3. Subjects have received strong or moderated cytochrome P450 3A4 (CYP3A4) inhibitors or CYP inducers such as ketoconazole, erythromycin, netupitant, isavuconazole etc. within 5 half-lives or 7 days (whichever is the shortest) prior to the first dose of study treatment. 4. Known history of or positive screening result for human immunodeficiency virus (HIV) antibody. 5. Viral hepatitis type B or C which require antiviral therapy, and/or have HBsAg (+) with HBV DNA ≥ 1000 IU/mL, or anti-HCV Ab (+) with HCV RNA (+). If a patient with HBsAg (+) then HBV DNA needs to be tested. If a patient with anti-HCV Ab (+) then the patient needs to be followed for HCV RNA (-) to be enrolled. 6. Uncontrolled systemic infection /or requiring isolation. 7. Patients with previous history of other malignant diseases within the last 5 years (other than adequately treated non-melanotic skin cancer, in-situ carcinoma of the uterine cervix or myelodysplastic syndromes). 8. Subjects with ongoing ≥ Grade 2 (CTCAE v5.0) toxicity (except alopecia and hot flashes) related to previous treatment. 9. Subjects have baseline QTcF interval \> 450 msec at screening (within 28 days prior to the first dose of study treatment, mean of triplicate readings within approximately 5 minutes). 10. Subjects have cardiovascular disability status of New York Heart Association (NYHA) ≥ Class III, left ventricular ejection fraction \< 45% at baseline, history of cardiac ischemia within the past 6 months, or prior history of cardiac arrhythmia requiring treatment. 11. Subjects have undergone any major surgery within 3 weeks prior to the first dose of study treatment. 12. Subjects with known active central nervous system (CNS) or leptomeningeal metastases. Subjects with previously-treated brain or meningeal metastases may participate and be eligible for treatment provided they are stable and asymptomatic (without evidence of progression by imaging of the brain at least 4 weeks prior to the first dose of study treatment), and are not using excessive steroids (defined as a prednisolone dose ≤ 10 mg daily or equivalent) for at least 2 weeks prior to the first dose of study treatment. 13. Subjects have had any of the following within 6 months prior to the first dose of study treatment: myocardial infarction, severe/unstable angina pectoris, coronary/peripheral artery bypass graft, symptomatic congestive heart failure, cerebrovascular accident or transient ischemic attack, or seizure disorder. 14. Subjects have any other medical or psychiatric condition that, in the opinion of the investigator, might interfere with the subject's participation in the trial or interfere with the interpretation of trial results.