Biopsy and re-biopsy for PD-L1 expression in NSCLC. association between PD-L1 and checkpoint inhibitor efficacy through treatment in NSCLC. A pilot study.

INTRODUCTION: Lung cancer is diagnosed at a late stage due to lack of early disease symptoms. Therefore an efficient treatment is necessary for prolonged disease free survival. PATIENTS AND METHODS: In our study we recruited 124 patients NSCLC patients with adenocarcinoma and squamus cell carcinoma. All recuited patients had Programmed death-ligand 1 expression ≥50 (PD-L1)with DAKO technique. Immunotherapy was administered with as first line treatment. Re-biopsies were performed in the main lung lesion every 4 months with the restaging of the patient and also in the metastastic sites in other organs that occurred during treatment. PD-L1 expressed was evaluated in the biopsies of the metastatic sites. RESULTS: It appears thereafter that the PD-L1 expression could easily be claimed as a promising bio-index with a cutoff value 65, below which a negative prognosis of the disease progress will be evident and above that value a positive continuation of the disease will be prominent. CONCLUSION: The findings of this study suggest that the PD-L1-65 index works adequately either concerning the neo-metastatic sites or the patient disease responses. Re-biopsies in new metastastic sites are necessary since we probably have a new cancer and chemotherapy should be added. More studies should confirm are results and change the NSCLC treatment approach of these patients.