Phase 1/2a Two-Arm Dose-Escalation Study of BAX69 in Subjects With Malignant Ascites of Ovarian Cancer

Inclusion Criteria: 1. Provision of a signed informed consent 2. Female participants of non-childbearing potential, ≥18 years of age 3. Anticipated life expectancy \>3 months at the time of screening 4. Metastatic ovarian epithelial cancer that are platinum-resistant, and has no better option available in the investigator's opinion 5. Recurrent symptomatic malignant ascites having required at least 2 paracenteses within a 45-day interval prior to baseline paracentesis 6. Participants who have an indwelling draining IP catheter (to be drained only under medical supervision) 7. Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 to 2 8. Adequate hematological function, defined as: * Platelet count ≥100,000/μL * Prothrombin time (PT) and activated partial thromboplastin time (aPTT) \<1.5 times the upper limit of normal (ULN) * Absolute neutrophil count ≥1,000/μL * Hemoglobin ≥9 g/dL, without the need for transfusion in the 2 weeks prior to screening 9. Adequate renal function, defined as serum creatinine ≤2.0 times ULN and creatinine clearance \>50 mL/min or estimated glomerular filtration rate (eGFR) \>50 mL/min/1.73 m\^2 10. Adequate liver function, defined as: * Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤2.5 times ULN for participants without liver metastases, or ≤5 times ULN in the presence of liver metastases * Bilirubin ≤2.0 times ULN, unless participant has known Gilbert's syndrome 11. Adequate venous access 12. Participant is willing and able to comply with the requirements of the protocol Exclusion Criteria: 1. Known central nervous system metastasis that is unstable within the last 2 months 2. Prior malignancy within the past 3 years, with the exception of curatively treated basal or squamous cell carcinoma of the skin, ductal carcinoma in situ of breast, in situ cervical carcinoma, and superficial bladder cancer 3. Residual AEs \>Grade 2 from previous treatment 4. Myocardial infarction within 6 months prior to C1D1 treatment, and/or prior diagnoses of congestive heart failure (New York Heart Association Class III or IV), unstable angina, unstable cardiac arrhythmia requiring medication; and/or the participant is at risk for polymorphic ventricular tachycardia (eg, hypokalemia, family history or long QT syndrome) 5. Uncontrolled hypertension defined as systolic blood pressure ≥160 mmHg and/or diastolic blood pressure ≥100 mmHg confirmed upon repeated measures 6. Left ventricular ejection fraction \<50% as determined by echocardiogram (ECHO) performed at screening or within 30 days prior to C1D1 7. QT/QTc interval \>480 msec, before C1D1 treatment administration, as determined by screening electrocardiogram (ECG) 8. Received anti-tumor therapy (chemotherapy, investigational product, radiotherapy, retinoid therapy, or hormonal therapy) within 2 weeks (less than 14 days) prior to C1D1 with no residual toxicity \>Grade 1; antibody therapy, molecular targeted therapy within 5 half-lives prior to C1D1 9. Major surgery within 4 weeks (less than 28 days) prior to C1D1 10. Active joint inflammation or other immune disorder involving joints (osteoarthritis is not exclusionary) 11. Active infection involving IV antibiotics within 2 weeks prior to C1D1 12. Positive serology test for hepatitis B virus (HBV), hepatitis C virus (HCV), or active tuberculosis 13. Positive serology test for human immunodeficiency virus (HIV) type 1 and 2, or known history of other immunodeficiency disease 14. Participant has received a live vaccine within 2 weeks (less than 14 days) prior to C1D1 15. Known hypersensitivity to any component of recombinant protein production by Chinese Hamster Ovary (CHO) cells 16. Any disorder or disease, or clinically significant abnormality on laboratory or other clinical test(s) (eg, blood tests and ECG), that in medical judgment of the investigator may impede the participant's participation in the study, pose increased risk to the participant, and/or confound the results of the study 17. Participant is a family member or employee of the investigator