General Inclusion:

          -  Written informed consent, according to local guidelines, signed and dated by the
             patient or by a legal guardian prior to the performance of any study-specific
             procedures, sampling or analyses

          -  Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0 or 1

          -  Measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1

          -  Acceptable renal, hepatic, hematologic and coagulation functions

          -  Negative pregnancy test for women of childbearing potential

          -  Male participants with female partners of childbearing potential and female
             participants of childbearing potential are required to follow highly effective
             contraception

          -  Availability of archived tumor samples or willingness to provide fresh tumor biopsy
             during screening for EphA2 assessment

        Additional inclusion criteria for Phase I (dose escalation phase, with BT5528 alone or in
        combination with nivolumab):

          -  Metastatic recurrent histologically confirmed malignant solid tumors confirmed to have
             EphA2 tumor expression. Confirmation of EphA2 expression prior to enrollment is not
             required for participants with ovarian cancer and specific other individual tumor
             types.

          -  Exhausted all appropriate treatment options per local guidelines

        Additional inclusion criteria for Phase II (dose expansion phase, with BT5528 alone or in
        combination with nivolumab):

          -  Participants with metastatic recurrent disease histologically confirmed to be
             adenocarcinoma subtype of NSCLC (adeno-NSCLC) or other tumor subtypes are eligible and
             must have exhausted all appropriate treatment options per local guidelines including
             progression on or after platinum-based chemotherapy and appropriate therapies for
             driver mutations (if applicable).

          -  Confirmed EphA2 tumor expression prior to enrollment, unless waived for specific tumor
             types

        Exclusion criteria (all participants):

          -  Chemotherapy treatments within 14 days prior to first dose of study treatment, other
             anticancer treatments, treatment within 28 days or 5 half-lives, whichever is the
             shorter

          -  Experimental treatments within 4 weeks of first dose of BT5528

          -  Current treatment with strong inhibitors or inducers of CYP3A4 or strong inhibitors of
             P-gp

          -  Uncontrolled, symptomatic brain metastases

          -  Any condition, therapy or laboratory abnormality that might confound the results of
             the study, interfere with the patient's participation, or is not in the best interest
             of the patient to participate in the opinion of the investigator including but not
             limited to specific cardiovascular criteria

          -  Thromboembolic events and/or bleeding disorders 3 months (e.g., deep vein thrombosis
             [DVT] or pulmonary embolism [PE]) prior to first dose

        Additional Exclusion Criteria (BT5528 in combination with nivolumab):

          -  Prior organ transplant (including allogeneic)

          -  Diagnosis of clinically relevant immunodeficiency

          -  Active systemic infection requiring therapy

          -  More than 10 mg daily prednisone equivalent or other strong immunosuppressant

          -  History of autoimmune disease except alopecia or vitiligo

          -  History of interstitial lung disease