Implementation of PD-L1 analysis among patients with non-small cell lung cancer in a single center

Nowadays, cancer immunotherapy is rapidly evolving and monoclonal antibodies targeting the programmed death‑1 receptor (PD‑1)/PD ligand 1 (PD‑L1) pathway have been approved for the treatment of NSCLC; however, there is lack of evidence regarding the current use of PD‑L1 analysis in the everyday clinical practice. For this purpose we conducted a retrospective observational study in our lung cancer oncology unit. Eligible patients were adults of both sexes with non‑small cell lung cancer who were treated in our department from April 2017 through December 2018. In total 123 patients were investigated regarding PD‑L1 expression using the immunohistochemistry assay 22C3. 108 out of 123 patients were male (87.8%) with a mean age of 67.5±9.3 years. 52 patients (42.3%) were diagnosed with squamous cell carcinoma, 63 (51.2%) with adenocarcinoma and 8 with NOS, adenosquamous and large cell carcinoma. Out of the 123 specimens, 4 were non eligible for PD‑L1 IHC analysis (<100 malignant cells/optical field). Sixty seven patients (54.5%) had PD‑L1 TPS scores <1% and 20 (16%) had PD‑L1 TPS scores ≥50%. Also 41 patients (33.3%) were treated with anti‑PD‑1 drugs (14 as first line, 19 as second and 8 as third). Eighteen of the patients who were treated with anti‑PD‑1 drugs were initially staged as IVA (43.9%) and 7 as IVB (17.1%). 14 out of 31 patients (20.4%) had disease control (8 SD and 6 PR/CR). In this retrospective analysis we found that the percentage of patients with PD‑L1 expression ≥50% was 16% which is much lower than it was usually noticed in clinical trials. This could be probably attributed to the high percentage of patients with early or locally advanced tumors who were included.