A Study of SGN-MesoC2 in Advanced Solid Tumors

Inclusion Criteria:

• Aged 18 years or older.

• Histologically- or cytologically-confirmed metastatic or locally advancedunresectable platinum-resistant ovarian cancer, NSCLC, pancreatic ductaladenocarcinoma, endometrial cancer, colorectal cancer, or mesothelioma, who haverelapsed or progressed following standard therapies, or for which no standardtherapies are available.

• An Eastern Cooperative Oncology Group performance status score of 0 or 1.

• At least 1 measurable lesion at baseline based on Response Evaluation Criteria inSolid Tumors Version 1.1 (RECIST v1.1).

• Archival tumor tissue or a fresh tumor biopsy during the screening period.

• Adequate hepatic, renal and bone marrow function.

• Participants must not have received more than 2 lines of cytotoxic systemic therapyin the metastatic setting (Parts B and C only).

Exclusion Criteria:

• Previously received or currently receiving any systemic anticancer therapy or focalradiotherapy within 4 weeks prior to the first dose of MesoC2 or within 2 weeksprior to the first dose of MesoC2 if the underlying disease had progressed ontreatment.

• Prior anti-MSLN antibody or MSLN-directed ADC (Part C only).

• Unresolved toxicities from prior therapy greater than NCI CTCAE v5.0 grade 1 at thetime of study treatment (except alopecia).

• Inadequate hepatic dysfunction, renal function, or hematologic abnormalities.

• Previously untreated brain metastases. Participants who received radiation orsurgery for brain metastases are eligible if therapy was completed at least 4 weeksprior to study treatment initiation, and there was no evidence of central nervoussystem progression nor requirements for chronic corticosteroid therapy