A Study of MGC026 in Participants With Advanced Solid Tumors

Inclusion Criteria:

• Adults ≥ 18 years old, able to provide informed consent

• Adequate performance and laboratory parameters

• Availability of archival or formalin-fixed paraffin-embedded tumor tissue sample.Participants may undergo a fresh tumor biopsy to obtain a specimen for testing if anarchival tumor sample is not available. Participants with no available archivaltissue sample who cannot safely undergo a fresh biopsy as determined by consultationbetween the sponsor and investigator are eligible

• Unresectable, locally advanced or metastatic solid tumors including: squamous cellcancer (SCC) of the head and neck, esophageal SCC, squamous and non-squamousnon-small cell lung cancer, small cell lung cancer, bladder cancer, sarcoma,endometrial cancer, melanoma, castration resistant prostate cancer, breast cancer,ovarian cancer, cervical cancer, colorectal cancer gastric or gastroesophagealcancer, pancreatic carcinoma, clear cell renal cell cancer or hepatocellular cancer.

• Measurable disease per RECIST v1.1. Participants with metastatic CRPC withoutmeasurable disease are eligible.

• Must be willing to use highly effective methods of birth control from the time ofconsent through 7 months after discontinuation of MGC026.

• Not pregnant or breastfeeding.

Exclusion Criteria:

• Any underlying medical or psychiatric condition impairing participant's ability toreceive, tolerate, or comply with the planned treatment or study procedures.

• Another cancer that required treatment within the past 2 years, with the exceptionof those with low risk of cancer spreading or death such as adequately treated nonmelanomatous skin cancer, localized prostate cancer (Gleason Score < 6), orcarcinoma in situ.

• Patients with history of prior central nervous system (CNS) metastasis must havebeen treated, be asymptomatic, and not have concurrent treatment for CNS disease,progression of CNS metastases on magnetic resonance imaging, computed tomography orpositron emission tomography, or history of leptomeningeal disease or cordcompression at the time of enrollment.

• Treatment with surgery, systemic cancer therapy, immunotherapy, chimeric antigenreceptor-T therapy, or anti-hormonal within protocol specified intervals.

• Prior treatment with any B7-H3 targeted agent for cancer or any ADC with atopoisomerase payload.

• Prior autologous or allogeneic stem cell or solid organ transplant.

• Clinically significant cardiovascular, pulmonary, or gastrointestinal disorders.

• Active viral, bacterial, or systemic fungal infection requiring parenteral treatmentwithin 1 week of first study drug administration.

• Known history of hepatitis B or C infection or known positive test for hepatitis Bsurface antigen or core antigen, or hepatitis C polymerase chain reaction.

• Known positive testing for human immunodeficiency virus or history of acquiredimmune deficiency syndrome.

• History of primary immunodeficiency.

• Major trauma or major surgery within 4 weeks of first study drug administration.

• Known hypersensitivity to recombinant proteins.