title: Exceptional response to cetuximab monotherapy in a patient with metastatic oropharyngeal squamous cell carcinoma: a molecular insight.
abstract: BACKGROUND
  Metastatic head and neck squamous cell carcinoma (HNSCC) carries a very poor prognosis. A better understanding of the molecular driver of the disease and the identification of biomarkers of response remain paramount for an effective personalized therapy.
  
  
  METHODS
  We report an original case of a 56-year-old patient diagnosed with metastatic HNSCC to both kidneys, who experienced a long-lasting complete response to a single-agent cetuximab, a monoclonal antibody-targeting EGFR. Comprehensive multiplatform biomarker analysis of the tumor revealed the presence of phosphatidyl-inositol 3 kinase mutation, EGFR overexpression, and the absence of PD-1/PD-L1 expression. Since PI3K, a downstream effector of EGFR, is activated, the tumor regression may have occurred mainly through a cetuximab-induced immune-mediated response, rather than EGFR signal blockade. It is plausible that this effect was enhanced by the lack of PD-1 and PD-L1 expression.
  
  
  CONCLUSIONS
  Our case proposes that the absence of PD-1 and PD-L1 expression in conjunction with EGFR overexpression may correlate with better response to cetuximab in HNSCC. This hypothesis needs to be examined through a large clinical trial.
authors.affiliation: Department of Medicine, Division of Hematology-Oncology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
authors.forename: Prakash
authors.initials: P
authors.lastname: Peddi
authors.affiliation: Department of Radiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
authors.forename: Bhavna
authors.initials: B
authors.lastname: Paryani
authors.affiliation: Department of Radiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
authors.forename: Amol
authors.initials: A
authors.lastname: Takalkar
authors.affiliation: Department of Head and Neck Surgery, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
authors.forename: Paige
authors.initials: P
authors.lastname: Bundrick
authors.affiliation: Oncology Department, Herbert J Thomas Memorial Hospital, South Charleston, WV, USA.
authors.forename: John
authors.initials: J
authors.lastname: Ponugupati
authors.affiliation: Baylor Scott & White Medical Center - Waxahachie, Waxahachie, TX, USA.
authors.forename: Binu
authors.initials: B
authors.lastname: Nair
authors.affiliation: Department of Medicine, Division of Hematology-Oncology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
authors.forename: Hazem
authors.initials: H
authors.lastname: El-Osta
keywords: EGFR blockade; biomarker; cetuximab; exceptional response; head and neck squamous cell carcinoma