As a proof of concept study, we analysed the MMP11 plasma levels in the NMRI (nu/nu) tumor-free healthy mice and in the NMRI (nu/nu) mice bearing subcutaneous head and neck squamous cell carcinoma (HNSCC) xenograft tumors and found a statistical trend toward increased MMP11 levels in the tumor-bearing mice (Figure S6D). This evidence concerns the gene MMP11 and head and neck squamous cell carcinoma.