The purpose of this study is to evaluate the safety, tolerability and maximum tolerated dose of tislelizumab in combination with pamiparib plus chemoradiotherapy (chemotherapy and radiation) in individuals with recurrent head and neck cancer, which means that the person's cancer has come back after treatment.~During the study, participants will first receive one dose of tislelziumab. Tislelzumab is an experimental drug, meaning, it is not approved by the U.S. Food and Drug Administration (FDA) to treat cancer. Next, participants will receive pamiparib in combination with CRT (chemotherapy and radiation). Pamiparib is also an experimental drug and not approved by the FDA.~Chemoradiotherapy will consist of chemotherapy drugs, 5-FU and hydroxyurea, plus radiation therapy. 5-FU is approved by the FDA to treat many types of cancer such as colon cancer but has not been approved for the treatment of head and neck cancer. Its use is experimental in this study. Hydroxyurea is approved by the FDA to treat many types of cancer, including in combination with radiation therapy for the local control of squamous carcinoma of the head and neck. The combination of tislelizumab, hydroxyurea with 5-FU, radiation, and pamiparib, is considered experimental in this study.~Participation in the study should last for about 15 months while participants receive tislelizumab and chemoradiotherapy with pamiparib. Afterwards, they will return to the clinic for follow up every 4 months for 2 years, every 6 month for the next 2 years, and then once a year for the rest of their life.
The purpose of this study is to evaluate the safety, tolerability and maximum tolerated dose of tislelizumab in combination with pamiparib plus chemoradiotherapy (chemotherapy and radiation) in individuals with recurrent head and neck cancer, which means that the person's cancer has come back after treatment.~Participation in the study should last for about 15 months while participants receive tislelizumab and chemoradiotherapy with pamiparib. Afterwards, they will return to the clinic for follow up every 4 months for 2 years, every 6 month for the next 2 years, and then once a year for the rest of their life.