⁃ Male/female participants who are at least 18 years of age on the day of signing informed consent with newly diagnosed, previously untreated, histologically and/or cytologically confirmed diagnosis of Stage II-IVb PNS SCC will be enrolled in this study.

⁃ Male participants:

⁃ A male participant must agree to use a contraception as detailed in Appendix 3 of this protocol during the treatment period and for at least 150 days after the last dose of study treatment and refrain from donating sperm during this period.

• Female participants:

⁃ A female participant is eligible to participate if she is not pregnant (see Appendix 3), not breastfeeding, and at least one of the following conditions applies:

‣ Not a woman of childbearing potential (WOCBP) as defined in Appendix 3 OR

‣ A WOCBP who agrees to follow the contraceptive guidance in Appendix 3 during the treatment period and for at least 150 days after the last dose of study treatment.

• The participant (or legally acceptable representative if applicable) provides written informed consent for the trial.

∙ Have measurable disease based on RECIST 1.1.

∙ Have provided archival tumor tissue sample or newly obtained core or excisional biopsy of a tumor lesion not previously irradiated. Formalin-fixed, paraffin embedded (FFPE) tissue blocks are preferred to slides. Newly obtained biopsies are preferred to archived tissue.

∙ Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1. Have adequate organ function as defined in the following table (Table 1). Blood must be collected within 14 days prior to the start of study treatment.