The purpose of this study is to evaluate investigational treatments (study drug) in people with recurrent or metastatic PD-L1-positive, HPV-negative head and neck squamous cell carcinoma without prior treatment. The goal is to determine the optimal dose level, safety, and tolerability for the study drug BCA101. This is a phase 2 study; BCA101 is not FDA approved by the U.S. Food and Drug Administration (FDA). Treatment for this study may be up to 5 years. The procedures include taking study drug intravenously, blood and urine samples, and CT scans. Risks include diarrhea, nausea, vomiting, mouth sore, nose bleed, headache, and skin rash. You may or may not receive a direct benefit from participating in this trial, however, information learned from the trial may help other people in the future.