Study to Test the Safety and Tolerability of PF-07257876 in Participants With Selected Advanced Tumors.

Inclusion Criteria:

Histological/cytological diagnosis of selected advanced or metastatic tumor
Prior treatment with PD-1 (Programmed cell death 1) or PD-L1 (programmed death-ligand 1) in NSCLC and SCCHN or platinum-based therapy in Ovarian cancer
Confirmed radiographic progression of disease
PD-L1 IHC positivity ≥1%
Have ≥1 measurable lesion as defined by RECIST 1.1 that has not been previously irradiated
Eastern Cooperative Oncology Group performance status 0-1
Adequate hematologic, renal and liver functions
Resolved acute effects of any prior therapy
Participants in Part 1 must be able to provide archival tumor tissue collected within the prior 6 months or consent to undergo a fresh biopsy during screening. Participants enrolled to the MTD (Maximum Tolerated Dose) cohort in Part 1 must consent to mandatory paired pre-treatment and on-treatment biopsies. Participants in Part 2 must consent to a pre-treatment biopsy and a subset of patients must consent to a paired on-study biopsy as well until the Sponsor deems an adequate number have been received.

Exclusion Criteria:

Participants with known brain metastasis larger than 4 cm or that is symptomatic. New brain metastases detected at screening. Participants with previously diagnosed brain metastases are eligible if they have completed treatment and recovered from acute effects prior to study entry.
Abnormal neurological assessment by investigator
Other active malignancy within 3 years prior to enrollment, except for adequately treated basal cell or squamous cell skin cancer, or carcinoma in situ
Major surgery or radiation therapy within 4 weeks prior to planned first dose
Last systemic anti-cancer therapy within 28 days or 5 half-lives (whichever is shorter) prior to planned first dose (6 weeks for mitomycin C or nitrosoureas)
Active bleeding disorder in the past 6 months prior to first dose
History of clinically significant severe immune mediated adverse event that was considered related to prior immune modulatory therapy and required immunosuppressive therapy (other than hormone replacement therapy)
History of idiopathic pulmonary fibrosis (including pneumonitis), drug-induced pneumonitis, organizing pneumonia (ie, bronchiolitis obliterans, cryptogenic organizing pneumonia), evidence of active pneumonitis on screening chest CT(computer tomography) scan
Anticoagulation with vitamin K antagonists or factor Xa inhibitors is not allowed
Treatment with chronic systemic corticosteroids or other immunosuppressive medications
Participation in other studies involving investigational drug(s) within 4 weeks prior to planned first dose
Active, uncontrolled bacterial, fungal, or viral infection, Hepatitis B, Hepatitis C, or Human immunodeficiency virus (HIV) infection
Active COVID-19/SARS-CoV2
Pregnant or breastfeeding female participant
Organ transplant requiring immunosuppressive treatment or prior allogeneic bone marrow or hematopoietic stem cell transplant
Significant cardiac or pulmonary conditions or events within previous 6 months