Academic Editor: Elena Levantini
Background: Determining predictive biomarkers for immune checkpoint
inhibitors (ICIs) is a current challenge in oncology. Previous studies on
non-small cell lung cancer (NSCLC) have shown how TP53 gene mutations
are correlated with different responses to ICIs. Strong and diffuse
immuno-expression of p53 by immunohistochemistry (IHC) is interpreted as a likely
indicator of a TP53 gene mutation. We aimed to assess the p53 protein
expression via IHC in NSCLC as a predictive biomarker of the response to ICIs.
Methods: This was a retrospective hospital-based study of patients with NSCLC
treated with Nivolumab in the University Hospital of Salamanca. All diagnostic
biopsies were studied via IHC (measuring p53 protein expression, peroxidase
anti-peroxidase immunohistochemistry technique using Leica BOND Polymer
development kits). Survival analysis was performed by subgroups of expression of
p53 and other factors using the Kaplan-Meier estimator and Cox
proportional-hazards model. Results: Seventy-three patients were included (59 men
and 14 women). The median age was 68 (44–84) years. Thirty-six biopsies were
adenocarcinoma, 34 were squamous, and three were undifferentiated. In 41 biopsies
(56.2%), the cellular expression of p53 was