Prognostic impact of PD-L1 in oropharyngeal cancer after primary curative radiotherapy and relation to HPV and tobacco smoking

• Published in: Acta oncologica 2020-06, Vol.59 (6), p.666-672
• Main Authors: Lilja-Fischer, Jacob K., Eriksen, Jesper G., Georgsen, Jeanette B., Vo, Thao T., Larsen, Stine R., Cheng, Jonathan, Busch-Sørensen, Michael, Aurora-Garg, Deepti, Steiniche, Torben, Overgaard, Jens
• Format: Article
• Language: English
• Subjects: Aged; Alphapapillomavirus; B7-H1 Antigen - analysis; B7-H1 Antigen - metabolism; Carcinoma, Squamous Cell - chemistry; Carcinoma, Squamous Cell - etiology; Carcinoma, Squamous Cell - mortality; Carcinoma, Squamous Cell - radiotherapy; Confidence Intervals; Female; Follow-Up Studies; Human papillomavirus 16; Humans; Male; Middle Aged; Neoplasm Proteins - analysis; Neoplasm Proteins - metabolism; Oropharyngeal Neoplasms - chemistry; Oropharyngeal Neoplasms - etiology; Oropharyngeal Neoplasms - mortality; Oropharyngeal Neoplasms - radiotherapy; Papillomavirus Infections - complications; Papillomavirus Infections - metabolism; Prognosis; Tobacco Smoking - adverse effects; Tobacco Smoking - metabolism
• ISSN: 0284-186X; 1651-226X
• DOI: 10.1080/0284186X.2020.1729407

Background: Incidence of oropharyngeal squamous cell carcinoma (OPSCC) is rising rapidly in many western countries due to Human papillomavirus (HPV) and tobacco smoking, with a considerable overlap. Immunotherapy directed at the PD1/PD-L1 axis have shown promise in head and neck cancer and other cancer types. PD-L1 expression may indicate a poorer prognosis, and at the same time indicate a possible benefit of anti-PD-L1 immunotherapeutic agents. The primary aim of this study was to establish the prognostic effect of PD-L1 expression after primary curative radiotherapy alone. Material and methods: A cohort of 303 OPSCC patients treated with primary, curative intended radiotherapy was established. PD-L1 expression was evaluated by immunohistochemistry on formalin fixed, paraffin embedded tissue sections. PD-L1 positivity was defined as a Combined Positive Score (CPS) ≥1, indicating staining of either tumor cells, lymphocytes or macrophages. Results: Median follow-up was 5.3 years. With 199 deaths, there was no difference in overall survival between patients with PD-L1+ and PD-L1− tumors (adjusted hazard ratio [aHR] and 95% confidence interval [CI]: 1.0 [0.71-1.4]). Also, locoregional failure was similar between the two groups (aHR 1.1 [CI: 0.68 − 1.7]). Tumors were PD-L1+ in 76% of cases, significantly more among HPV p16+ tumors (82% vs. 70%, p = .01). Interestingly, higher prevalence of PD-L1+ expression was seen in HPV p16+ patients with