A Study to Learn About How Different Amounts of the Study Medicine PF-07826390 Act in the Body of People With Cancer When Taken Alone or With Other Anti-cancer Medicines.

FIRST-IN-HUMAN (FIH), OPEN-LABEL, PHASE 1 DOSE ESCALATION AND EXPANSION STUDY DESIGNED TO EVALUATE THE SAFETY, TOLERABILITY, PK, PD, AND PRELIMINARY CLINICAL ACTIVITY OF PF-07826390 AS A SINGLE AGENT OR IN COMBINATION TREATMENT FOR PARTICIPANTS WITH ADVANCED SOLID TUMORS.

The purpose of this study is to learn about the:

• safety (the effect of the study medicine on the participant's body),
• effects of the study medicine alone or in combination with sasanlimab -
• the best amount of the study medicine.

This study is seeking participants who have solid tumors (An abnormal mass of tissue) that:

• have advanced (cancer that does not disappear or stay away with treatment) or
• are metastatic (has spread to other parts of the body).

This includes (but limited to) the following cancer types:

• Non-Small Cell Lung Cancer (NSCLC): It's a type of lung cancer where the cells grow slowly but often spread to other parts of the body.
• Colorectal Cancer (CRC): This is a disease where cells in the colon or rectum grow out of control.
• Renal Cell Carcinoma (RCC): This is a cancer that starts in the kidney.

All participants in this study will receive the study medication (PF-07826390) as an IV infusion (given directly into a vein) at the study once every four weeks in 28 day cycles.

The study participants depending on the group enrolled in, will receive the study medication (PF-07826390 alone or in combination with other anti-cancer medications (sasanlimab). Sasanlimab is given as a shot under the skin every 4 weeks.

Participants can continue to take the study medication (PF-07826390) until their cancer is no longer responding. Participants who are taking sasanlimab may receive it for up to 2 years.

The study will look at the experiences of people receiving the study medicines. This will help see if the study medicines are safe and effective.

Participants will be involved in this study for up to 4 years. During this time, participants will have a study visit every week. The participants after stopping the study medicine (at about 2 years) will be followed for another two years to see how the participants are doing.

Inclusion Criteria:

• Histological or cytological diagnosis of advanced, unresectable, and/or metastatic or relapsed/refractory solid tumor
• Part 1A: Participants with solid tumors where anti-PD-(L)1 is an established treatment. Participants must have progressed on or following prior anti-PD-(L)1 therapy if approved, available, tolerable, and eligible
• Part 1B: Participants either meeting Part 1A criterion, or participants with "cold" solid tumors where anti-PD-(L)1 therapy is not an established treatment
• Part 2: Participants with NSCLC (2A Arm 1 and 2B) must have received platinum-based chemotherapy and anti-PD-(L)1 or have intolerability to or refusal of standard therapies. Participants with NSCLC who have not been previously treated with a prior anti-pd-(L) will be enrolled in Part 2C.
• Participants with MSS CRC (Part 2A Arm 2) must have received fluoropyrimidine-, oxaliplatin, and irinotecan-based chemotherapy, an anti-VEGF agent and anti-EGFR inhibitor (if RAS wildtype) and/or other molecularly targeted therapy if appropriate. Participants with RCC (Part 2A Arm 3) must have received prior tyrosine kinase inhibitor (TKI), anti-PD-(L)1 (if not receiving anti-PD-1 on protocol), anti-CTLA-4 (optional), hypoxia-inducible factor 2 alpha (HIF2a) inhibitor, or mTOR inhibitor or have documented intolerance to the standard therapy.
• At least 1 measurable lesion based on RECIST 1.1 that has not been previously irradiated (Part 1 exceptions permitted after review and approval)
• Able to provide pre-treatment (and optional on-treatment) tumor tissue

Exclusion Criteria:

• Treatment with any systemic anticancer therapy within 4 weeks or 5 half-lives (whichever is shorter) prior to planned first dose
• Active or history of clinically significant autoimmune disease or other medical condition that required chronic systemic immunosuppressive therapy within recent 2 years
• Prior treatment with another LILRB1 (ILT2), LILRB2 (ILT4), and/or LILRB1/2 (B1 and B2) antagonist antibodies or pathway targeting agents, including HLA conformers and HLA-G antibodies.
• Lack of adequate organ (bone marrow, renal, liver) function
• History of severe immune-mediated adverse event or cytokine release syndrome that was considered related to prior immune modulatory therapy that required immunosuppressive therapy