In the IMCISION trial in patients with HNSCC comparing major pathological response (MPR) between treatment arms with nivolumab or nivolumab plus ipilimumab prior to extensive surgery, biomarkers such as higher PD-L1 expression, increased intratumoral CD8+ T cell infiltration, and the presence of APOBEC-associated mutations were all linked to MPR following neoadjuvant immunotherapy with nivolumab and ipilimumab [59]. Here, CD8A is linked to head and neck squamous cell carcinoma.