• Histologically- or cytologically-confirmed advanced or metastatic malignancy, defined as:

• One of the following tumor types:

• Unresectable locally-advanced or metastatic non-small cell lung cancer (NSCLC), gastric/gastroesophageal (GE) junction carcinoma, cutaneous melanoma, head and neck squamous cell carcinoma (HNSCC), bladder cancer, cervical cancer, ovarian cancer, or triple negative breast cancer (TNBC)

• Lymphomas, including:

• Classical Hodgkin lymphoma (cHL)

• Diffuse large B-cell lymphoma (DLBCL)

• Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS)

• Lymphoma: Participants should have disease progression on or after treatment with standard therapies expected to provide benefit in the judgement of the investigator.

• cHL: Participants must have received at least 3 prior systemic therapies. Participants should have had disease recurrence or progression following brentuximab vedotin therapy or have been ineligible to receive brentuximab vedotin. Participants who have not received autologous stem cell transplant (SCT) must have refused or been deemed ineligible. Participants should have received or not be eligible to have received an anti-PD-1 agent.

• DLBCL: Participants must have received at least 2 prior systemic chemo-immunotherapy regimens, including an anti-CD20 agent and combination chemotherapy. Unless clinically contraindicated, participants should have had disease that has relapsed after or be refractory to intensive salvage chemotherapy, including autologous SCT.

• PTCL-NOS: Participants must have had at least 1 prior systemic therapy. Participants must have received or have been ineligible to receive the combination of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or CHOP-like therapy. Participants with CD30-positive disease must have received or be ineligible to receive brentuximab vedotin. Participants must have also received intensive salvage therapy (defined as combination chemotherapy ± autologous SCT) unless they refused or were deemed ineligible.

• Measurable disease defined as:

• Solid tumors: Measurable disease according to RECIST V1.1

• Lymphomas: Fluorodeoxyglucose (FDG)-avid disease by positron emission tomography (PET) and measurable disease of ≥15 mm in the greatest transverse diameter by computed tomography (CT) scan, as assessed by the site radiologist.

• A representative archival tumor tissue sample should be available as follows: Participants must provide archived tumor tissue, if available, from the most recent biopsy (≤12 months from screening). If archived tissue is not available, a fresh baseline tumor biopsy will be requested for any participant enrolled in Part B whose tumors are considered accessible and appropriate in the opinion of the investigator.

• ECOG Performance Status score of 0 or 1

• ECOG Performance Status score of 0 or 1

• NSCLC: histological or cytological confirmed metastatic disease. Participants must have received no prior anti-PD-1/PD-L1 therapy allowed.

• HNSCC: histological or cytological confirmed metastatic disease. Participants must have received no prior exposure to anti-PD-1/PD-L1 therapy.

• Cutaneous Melanoma: histological or cytological confirmed metastatic disease. Participants must not have received anti-PD-1/PD-L1 targeted therapy.

• Measurable disease by CT or magnetic resonance imaging (MRI) as defined by RECIST V1.1

• Participants must provide archived tumor tissue, if available, from the most recent biopsy (≤12 months from screening). If archived tissue is not available, a fresh screening tumor biopsy will be requested for any participant whose tumors are considered accessible and appropriate in the opinion of the investigator.

• Prior use of any anti-TIGIT mAb.

• Participants with a condition requiring systemic treatment with either corticosteroids (>10 mg daily prednisone or equivalent) or other immunosuppressive medications within 14 days of enrollment. Inhaled or topical steroids and adrenal replacement steroid doses >10 mg daily prednisone or equivalents are permitted in the absence of active immune disease.

• Known hypersensitivity to any excipient contained in the drug formulation of SEA-TGT