Abstract 207P
Background
Tumor-programmed death ligand 1 (PD-L1) expression is a key biomarker analyzed in patients diagnosed with advanced non-small cell lung cancer (NSCLC). It is important to determine the real-world prevalence of PD-L1 expression and indicate differences in clinically relevant patient subgroups-including the elderly population.
Methods
Samples of patients (pts) who qualified for the first-line treatment of advanced NSCLC in 2017–2022 were analyzed. Immunohistochemistry was performed using the PD-L1 kit (PD-L1 IHC 22C3 pharmDX; Dako). Descriptive analysis, applying chi-square test to compare PD-L1 categories between groups, and logistic regression to calculate odds ratios were performed.
Results
A samples of 1710 pts were analyzed. The median age was 68 years, 34.5% of pts were <65 while 17.3% were >75 years old. The prevalence of squamous-cell carcinoma in the entire population was 35.7%, adenocarcinoma 51.5%, NOS 2.7% and other types 10.1%. PD-L1 expression ≥50% was found in 33.3% of pts, while 1–49% and <1% in 23.8% and 42.8% of pts, respectively. In 5% of the cases, no reliable test result was obtained due to insufficient cellularity of specimens (<100). PD-L1 expression <1% was observed more frequently in patients with non-squamous carcinoma (46.3% vs 37.1%; p = 0.001). Other variables - gender and type of sample (excisional biopsy, thick needle biopsy) - of the entire population, had no impact on the prevalence of PD-L1 expression. Additional analysis was performed in subgroups in relation to age. In the group of patients >65 years of age, no differences were observed for expression levels >1% (p = 0.280) and >50% (p = 0.368), similarly in the group of patients >75 years of age – p = 0.169 and p = 0.882, respectively. However, subgroup analysis indicated a higher probability of <1% expression in patients >65 years of age with a diagnosis of non-squamous carcinoma (OR 0.65, p = 0.00; 95% CI 0.49–0.85).
Conclusions
Analysis of a large cohort of patients indicated an association between non-squamous cancer type in elderly pts and a higher incidence of PD-L1 <1% expression. In 5% of analyzed pts, tests were not feasible. Alternative diagnostic methods for PD-L1, including soluble forms of biomarkers, are needed.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
M. Knetki-Wroblewska: Financial Interests, Personal, Invited Speaker: Bristol Myers Squibb, Roche, MSD, Takeda, Amgen, AstraZeneca, Boehringer Ingelheim, Ipsen; Financial Interests, Personal, Advisory Board: Takeda, Boehringer Ingelheim, Bristol Myers Squib. P. Wiśniewski: Financial Interests, Personal, Invited Speaker: MSD. M. Krzakowski: Financial Interests, Personal, Advisory Board: MSD, Roche, AstraZeneca, BMS, Amgen; Financial Interests, Personal, Other, Travel grant: Roche, AstraZeneca. M. Prochorec-Sobieszek: Financial Interests, Personal, Invited Speaker: MSD. All other authors have declared no conflicts of interest.