We are doing this study to find the most effective, safe dose of an experimental drug called petosemtamab (the study drug). We also want to know how well it works compared to the standard treatments used for metastatic/recurrent head and neck squamous cell carcinoma (HNSCC).

Metastatic/Recurrent Head and Neck Squamous Cell Carcinoma (HNSCC)

Adults ages 18+ who:

• Are diagnosed with HNSCC that is metastatic or locally advanced
• Had their disease progress during or after anti-PD-1 therapy and platinum-containing therapy
• Have a primary tumor in one of the following locations: oropharynx, oral cavity, hypopharynx, or larynx

For more information about who can join this study, please contact the study team at 919-681-6807.

There are 3 periods in this study:

• Screening period - to find out if you are eligible
• Study drug period - the period when you will receive either the study drug or an assigned standard of care treatment
• Follow-up period - to see how you are doing after you stop taking the study drug or your assigned treatment

If you are found to be eligible during screening, you will proceed to the study drug period. During this period, you will get a random assignment (by chance) to either take the study drug or take whatever standard therapy the study doctor believes is most appropriate for you.

• If you are assigned to take the study drug, you will get it as an intravenous (IV) infusion every 2 weeks.
• If you are assigned to get a standard treatment, the study doctor will choose 1 of the following 3 drugs to treat you: cetuximab, methotrexate, or docetaxel. Each of these drugs is given weekly.

The follow-up period will begin whenever you discontinue taking the study drug or chosen treatment.