Immunohistochemical Assessment of the P53 Protein as a Predictor of Non-Small Cell Lung Cancer Response to Immunotherapy.

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 <5% (Group A), and in 32 biopsies (43.8%), the expression was ≥5% (Group B). In the general analysis, no differences were observed in overall survival (OS) (A: 12 months vs B: 20 months; p = 0.070) or progression-free survival (PFS) (A: 4 m vs B: 7 m; p = 0.064). Significant differences were observed in adenocarcinomas for both OS (A: 8 m vs B: median not reached; p = 0.002) and PFS (A: 3 m vs 8 m; p = 0.013). No differences in PFS and OS were observed in squamous cell carcinoma. Significant differences were observed in OS in the PD-L1 negative group (0% expression) (A: 13 m vs B: 39 m; p = 0.024), but not in PFS (A: 3 m vs B: 7 m; p = 0.70). No differences were observed in the PD-L1 positive group. CONCLUSIONS: A trend toward a greater response to ICIs was observed in the PFS and OS of patients with high expression of p53 by IHC (TP53 mutation), especially in the PD-L1 negative adenocarcinoma subgroup. These results will make it possible to make future modifications to the clinical guidelines of NSCLC according to the expression of p53.

Influence of DNA Mismatch Repair (MMR) System in Survival and Response to Immune Checkpoint Inhibitors (ICIs) in Non-Small Cell Lung Cancer (NSCLC): Retrospective Analysis.

Mutations in the mismatch repair (MMR) system predict the response to immune checkpoint inhibitors (ICIs) like colon or gastric cancer. However, the MMR system's involvement in non-small cell lung cancer (NSCLC) remains unknown. Addressing this issue will improve clinical guidelines in the case of mutations in the main genes of the MMR system (MLH1, MSH2, MSH6, and PMS2). This work retrospectively assessed the role that these gene mutations play in the response to and survival of ICIs in NSCLC. Patients with NSCLC treated with nivolumab as the second-line treatment in the University Hospital of Salamanca were enrolled in this study. Survival and response analyses were performed according to groups of MMR system gene expression (MMR expression present or deficiency) and other subgroups, such as toxicity. There was a statistically significant relationship between the best response obtained and the expression of the MMR system (p = 0.045). The presence of toxicity grade ≥ 3 was associated with the deficiency expression of MMR (dMMR/MSI-H) group (p = 0.022; odds ratio = 10.167, 95% confidence interval (CI) 1.669-61.919). A trend towards greater survival and response to ICIs was observed in NSCLC and dMMR. Assessing the genes in the MMR system involved in NSCLC is key to obtaining personalized immunotherapy treatments.

[Patients with clinical criteria for Lynch syndrome with and without mutations in DNA repair genes (MLH1 and MSH2). A challenge for the clinician]. / Pacientes con criterios clínicos de síndrome de Lynch con y sin mutación en genes reparadores del ADN (MLH1 y MSH2). Un reto para el clínico.

BACKGROUND AND OBJECTIVES: The objective was to study the clinicopathologic characteristics of patients diagnosed of colorectal cancer (CRC) with clinical criteria for Lynch syndrome, in our region, in order to assess and improve the care of them and their families in the Genetic Counseling Unit of our hospital. PATIENTS AND METHODS: This was an observational, transversal retrospective study. The studied sample was made up of all the patients with clinical criteria for Lynch syndrome, who underwent a molecular analysis test in the Genetic Counseling Unit of Salamanca, during the period 2004-2009. We included patient and tumor related variables and the presence or absence of mutations in MLH1 and MSH2. RESULTS: A total of 76 patients were included in the analysis. Fifteen of them carried a mutation either in MLH1 or in MSH2. The mean age at diagnosis of colorectal cancer was 51.2 and 54.3 years in the group with and without mutation respectively, with a similar gender distribution in both groups. A wide phenotypic heterogeneity was found in the sample. CONCLUSIONS: Lynch syndrome is an entity difficult to categorize from a clinical point of view. Therefore, it is important to be alert for a better management of these patients and their families.