Study to Test the Safety and Tolerability of PF-07209960 in Advanced or Metastatic Solid Tumors

Inclusion Criteria:

* Histological/cytological diagnosis of selected locally advanced or metastatic solid tumor
* Demonstrated radiographic progression on most recent tumor assessment imaging
* Have ≥1 measurable lesion as defined by RECIST 1.1 that has not been previously irradiated
* Eastern Cooperative Oncology Group performance status 0-2 for Part 1 and 0-1 for Part 2
* Adequate hematologic, renal, liver, and coagulation functions
* LVEF ≥50% by echocardiogram or MUGA
* Resolved acute effects of any prior therapy
* Participants in Dose Expansion (Part 2) must have ≥2 prior lines of standard of care therapy
* Able to provide tumor tissue for submission to the Sponsor, including mandatory pre-treatment tumor biopsy (adequate archival tissue within the past 1 year is accepted in lieu of new biopsy) for all participants. Participants in Part 2 must also be able to undergo new (de novo) tumor biopsy at baseline (pre-treatment) and on-treatment biopsy until the Sponsor deems that an adequate number of biopsied samples have been received.

Exclusion Criteria:

* Known active symptomatic brain or leptomeningeal metastases requiring steroids.
* 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 4 weeks prior to planned first dose (6 weeks for mitomycin C or nitrosoureas). Participants who received anti-PD-1 therapy require an interval of 90 days prior to first dose
* Participation in other studies involving investigational drug(s) within 4 weeks prior to planned first dose
* Active and clinically significant bacterial, fungal, or viral infection; Hepatitis B or Hepatitis C infection, AIDS-related illness (HIV+ and in good immune health as defined in the protocol may be eligible)
* Active COVID-19/SARS-CoV2
* Anticoagulation with vitamin K antagonists is not allowed
* 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 interstitial lung disease or pneumonitis
* Organ transplant requiring immunosuppressive treatment or prior allogeneic bone marrow or hematopoietic stem cell transplant
* Pregnant or breastfeeding female participant