Anti PD-L1 antibody: is there a histologic-oriented efficacy? Focus on atezolizumab in squamous cell non-small cell lung cancer

Squamous cell lung cancer (SqCLC) is the second most common histotype of non-small cell lung cancer (NSCLC) and is characterized by severe prognosis and lack of specific target agents. Atezolizumab is the first anti Programmed Death Ligand-1 (PDL-1) inhibitor approved for NSCLC patients of both histology in case of disease progression after first or further lines of therapy. Numerous studies are investigating the potential role of atezolizumab in different therapeutic setting, including Sq- CLC subtype. We searched for published clinical trials in Pubmed database, using the terms "atezolizumab", "squamous cell lung cancer", "NSCLC"and "non-small cell lung cancer". We also searched for recently concluded and not yet published or ongoing trials in clinicaltrials.gov and in data from the latest international congresses. The aim of this review is to summarize current evidence on atezolizumab in SqCLC, from first line setting to novel potential indications from ongoing trials. Strengths and weaknesses of atezolizumab treatment were highlighted to speculate the role of this immune checkpoint inhibitor in novel future clinical scenarios.