This phase 1 study is aimed at establishing the safety basis of OT-A201 in the treatment of hematological malignancies and solid tumors. In the dose of escalation part it is to characterize the overall safety and tolerability profile and determine the recommended dose(s) of OT-A201 as monotherapy, and in various combination regimens. Preliminary information about anti-cancer activity will be further explored in the expansion part of the study.

Main Inclusion Criteria:

• Histologically or cytologically confirmed relapsed/refractory hematological malignancy or advanced/metastatic solid cancer
• Measurable disease
• Have had all available therapeutic standards for their disease
• Willingness to undergo baseline biopsy/bone marrow aspiration in case biopsy was not collected after completion of the most recent prior therapy
• ECOG performance status ≤ 1
• Life expectancy > 3 months as assessed by the investigator
• Acceptable clinical lab results

Main Exclusion Criteria:

• Systemic steroids at a daily dose of > 10 mg of prednisone or equivalent within 28 days before study treatment. Transient use of steroids for other medical condition may be allowed
• Ongoing immune-related adverse events irAEs and or AEs ≥ grade 2 from previous therapies not resolved except vitiligo, stable neuropathy up to grade 2, hair loss, and stable endocrinopathies with substitutive hormone therapy
• Within 4 weeks of major surgery
• Documented history of active autoimmune disorder requiring systemic immunosuppressive therapy within the last 12 months
• Prior solid organ transplant
• Primary or secondary immune deficiency
• Active and uncontrolled infection requiring intravenous antibiotic or antiviral treatment
• Seropositive (except after vaccination or confirmed cure for hepatitis) for human immunodeficiency virus (HIV), hepatitis B virus (HBV), or hepatitis C virus (HCV)
• Clinically significant disease