A Study of PF-08046049/SGN-BB228 in Advanced Melanoma and Other Solid Tumors

Inclusion Criteria:

• All Parts: Participants must have disease that is relapsed, refractory, orintolerant to standard of care. Participants must have histologically orcytologically confirmed metastatic malignancy.

• Participants must have one of the following tumor types:

• Parts A and B: Participants must have metastatic or unresectable cutaneousmelanoma.

• Part C: Participants must have one of the following tumor types:

• Cutaneous Melanoma

• Non-small Cell Lung Cancer (NSCLC)

• Colorectal Cancer (CRC)

• Pancreatic Cancer

• Mesothelioma

• A pre-treatment biopsy or submission of archival tissue is required

• For participants with cutaneous melanoma

• Must have been previously treated with an anti-programmed death-1 (anti-PD-1)or anti-programmed death ligand-1 (anti-PD-L1) agent given alone or with othertherapies.

• Participants with a targetable BRAF mutation must have been treated with, beenintolerant of, or been deemed ineligible to receive treatment with BRAF/MEKtargeted therapy prior to study entry.

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

• Measurable disease per RECIST v1.1 at baseline

Exclusion Criteria:

• History of another malignancy within 3 years before the first dose of study drug, orany evidence of residual disease from a previously diagnosed malignancy. Exceptionsare malignancies with a negligible risk of metastasis or death.

• Active central nervous system metastases or leptomeningeal disease. Participantswith previously treated brain metastases may participate provided they are:

• clinically stable for at least 4 weeks prior to study entry after brainmetastasis treatment,

• they have no new or enlarging brain metastases,

• and are off of corticosteroids prescribed for symptoms associated with brainmetastases for at least 7 days prior to the first dose of study drug.

• Prior therapies cannot include any drugs targeting CD228 or 4-1BB

• Immunotherapy, biologics, and/or other approved or investigational antitumortreatment that is not completed 4 weeks prior to first dose of study drug, or within 2 weeks prior to the first dose of study drug if the underlying disease hasprogressed on treatment

• Melanoma subtypes including acral, uveal, and mucosal are excluded