• Disease indication

‣ Participants must have histologically or cytologically confirmed metastatic or unresectable solid malignancy within one of the tumor types listed below (dependent on study part).

• Non-small cell lung cancer (NSCLC)

∙ Head and neck squamous cell cancer (HNSCC)

∙ Advanced HER2-negative breast cancer

∙ Esophageal squamous cell carcinoma (ESCC)

∙ Esophageal/Gastro-esophageal junction adenocarcinoma (EAC/GEJ)

∙ Cutaneous squamous cell cancer (cSCC)

∙ Exocrine pancreatic adenocarcinoma

∙ Bladder cancer

∙ Cervical cancer

∙ Gastric cancer

∙ High grade serous ovarian cancer (HGSOC)

⁃ Part A only: Participants must have disease that is relapsed or refractory or be intolerant to standard-of-care therapies and should have no appropriate standard-of-care therapeutic options.

⁃ Part B only: Participants must have disease that is relapsed or refractory or be intolerant to standard-of-care therapies. Participants must have received platinum-based therapy and a PD-1/PD-(L)1 inhibitor, if applicable and available.

⁃ Part C only: For pembrolizumab combination cohorts, participants must be eligible for pembrolizumab per local standard of care. For pembrolizumab with cisplatin or carboplatin, participants must be eligible for both pembrolizumab and the platinum agent per local standard of care. Participants must be treatment naïve for locally advanced or metastatic systemic therapy (prior definitively intended or \[neo\]adjuvant therapy is allowed).

⁃ Part D only: Participants must be treatment naïve for locally advanced or metastatic systemic therapy.

• Participants enrolled in the following study parts should have a tumor site accessible for biopsy and agree to biopsy as follows:

‣ Disease-specific expansion cohorts (Part B and Part D): A baseline fresh tumor biopsy is required. An archival biopsy collected within 90 days prior to first dose of study drug may be used.

⁃ Biology expansion cohort: pretreatment biopsy and on-treatment (Cycle 1) biopsy

• An Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1

• Measurable disease per the RECIST v1.1 at baseline