Carcinoma, Squamous Cell of Head and Neck

The purpose of the study is to explore the safety and effects of the study drug (PF-08046876) in people diagnosed with advanced cancer of the bladder, lung, head and neck, esophagus, or pancreas. PF-08046876 is an investigational anticancer therapy called an 'antibody drug conjugate' or 'ADC'. ADCs are anticancer drugs designed to stick to cancer cells and kill them. The study drug will be given to participants through a needle in a vein (intravenous infusion). This study includes multiple parts. In the first part of the study, there will be different groups of people receiving different doses of the study drug. The study may also test different schedules.