A Study to Learn About the Study Medicine (Called PF-07220060 in Combination With PF-07104091) In Participants With Breast Cancer and Solid Tumors

Exclusion Criteria

• All Study Parts: Permanent treatment discontinuation from prior CDK 4 and/or CDK2 inhibitor due to treatment related toxicity.

• Part 2B and 1C: Prior treatment with any CDK 4/6 inhibitor, or SERDs (e.g. fulvestrant), or everolimus, or any agent whose mechanism of action is to inhibit the PI3K-mTOR pathway for advanced disease.

• Parts 2B and 2C: Prior treatment with any CDK4/6 inhibitor for advanced disease.

• Parts 2B and 2C: Prior treatment with an investigational endocrine therapy for advanced disease.

• Part 2C: Prior neoadjuvant or adjuvant treatment with a nonsteroidal aromatase inhibitor AI (ie, anastrozole or letrozole) with disease recurrence while on or within 12 months of completing treatment.

• Part 2C: Any prior systemic treatment for advanced disease.

• Prior irradiation to >25% of the bone marrow

• Current use of drugs which have a risk for QTc prolongation

• Current use or anticipated need for food or drugs that are known strong CYP3A4/5, strong UGT2B7 or UGT1A9 inhibitors or inducers

• Participation in other studies involving investigational drug(s) within 4 weeks prior to study entry

  • Participants with any other active malignancy within 3 years prior to enrollment except for adequately treated basal cell or squamous cell skin cancer, or carcinoma in situ of the cervix, Bowen's disease
  • Major surgery within 4 weeks prior to study entry
  • Radiation therapy within 4 weeks prior to study entry.
  • Clinically important hypertension
  • Known or suspected hypersensitivity to PF-07220060, PF-07104091, letrozole, fulvestrant, or goserelin (or equivalent to induce chemical menopause if applicable)

• Known abnormalities in coagulation. Anticoagulation with subcutaneous heparin or prophylactic doses of anticoagulant are allowed

• Known active uncontrolled or symptomatic central nervous system (CNS) metastases

• Active inflammatory GI disease

• Current use or anticipated need for Proton Pump Inhibitors (PPI) within 14 days prior to first dose of the study intervention

• Previous high-dose chemotherapy requiring stem cell rescue

• Participants with active, uncontrolled bacterial, fungal, or viral infection, including hepatitis B virus (HBV), hepatitis C virus (HCV), and known human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) related illness

• Other protocol specific exclusion criteria may apply