Squamous-cell carcinoma (SCC) of the lung is the second most frequent histology in non-small cell lung cancer (NSCLC). Over the last decade new approaches targeting specific pathways in NSCLC have emerged but very few advances were made in its treatment. The PI3K-AKT-mTOR pathway is implicated in multiple cancer processes and PIK3CA mutations are being investigated in SCC as potential therapeutic target. The aim of the study was to evaluate the histological characteristics, mutations in PIK3CA and PD-L1 expression in these tumors.
Surgically resected lung SCC samples (FFPE) from 100 patients, stage I-III, were included in this study. Clinicopathologic characteristics included tumor size, TNM, smoking status, lymphovascular and pleural invasion, histopathological grade, stromal lymphoplasmacytic reaction and type of tumoral growing. DNA was isolated from 92 samples according to standard procedures and PIK3CA mutation analysis was done using Cobas 4800 platform. PD-L1 expression was analyzed in 74 cases by immunohistochemistry with PDL1 22C3 pharmDX assay. The PD-L1 expression was evaluated by tumor proportion scores (TPS) as IASLC guidelines.
The mean age was 68 years (53-86), 14 females and 86 males. About staging: 53 patients had stage I, 27 stage II, and 19 stage III. 53% and 35% showed vascular and pleural invasion respectively. Low to moderate stromal lymphoplasmacytic reaction was found in 34% and severe in 11%. PI3KCA mutation was found in 9/92 (9,8%) patients: E545X (n = 2), E542K (n = 5), H1047X (n = 1), C420R (n = 1). PD-L1-expression was found in 31 out of 74 cases (42%): 14 cases with TPS between 1-49%; 17 cases with TPS >50%. 5/9 (55%) of PIK3CA mutated cases were PD-L1 positive (2 of them >50%). In PIK3CA non-mutated cases 26 out of 67 (39%) showed PD-L1 expression: 11 cases with TPS between 1-49%; 15 cases with TPS >50%.
PIK3CA mutation was found in 9,8% of SCC of the lung, most of them in exon 9. PD-L1 expression was found in 42% of the SCC in our series. 55% of PIK3CA mutated patients were positive for PD-L1 expression. No correlation has been found between PD-L1 expression and PIK3CA mutation in SCC. It is important to know more about the relation of these factors to select the patients for immunotherapy and new target agents.
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All authors have declared no conflicts of interest.