Comparison of programmed death-ligand 1 (PD-L1) immunostain for nonsmall cell lung carcinoma between paired cytological and surgical specimens

Abstract

Background:programmed death-ligand 1 (PD-L1) is a ligand for the inhibitory programmed cell death protein 1 (PD-L1), which are targeted by several anti-PD-1 and PD-L1 drugs for lung cancer treatment. In clinical practice, many lung cancer cases only have cytology samples available to test PD-L1. Our current study compared the PD-L1 immunohistochemistry (IHC) between paired cytological and surgical samples.Materials and Methods:Formalin-fixed lung cancer tissue microarray and paired cell blocks and surgical specimens from the same patients with a confirmed diagnosis of lung squamous cell carcinoma (SCC, n = 29) and adenocarcinoma (AC, n = 23) were sectioned for PD-L1 IHC.Results:PD-L1 was expressed on tumor cells in 16 of 29 (55%) SCC surgical specimens and 18 of 29 (62%) paired cytologic specimens with 83% matched immunostains. PD-L1 was expressed on tumor cells in 13 of 23 (57%) AC surgical specimens and in 17 of 23 (74%) paired cytologic specimens with 79% matched immunostains. The PD-L1 was expressed on inflammatory cells in 20 of 23 (87%) AC surgical specimens and in 15 of 23 (65%) paired cytologic specimens with 70% matched immunostains. The PD-L1 was expressed on inflammatory cells in 18 of 29 (62%) SCC surgical specimens and in 12 of 29 (41%) paired cytologic specimens with 79% matched immunostains.Conclusions:PD-L1 immunostain in cytology samples matched very well with paired surgical samples in both SCC and AC cases. The cytologic samples present slightly higher sensitivity for PD-L1 immunostain on tumor cells as compared to surgical biopsies.

Programmed death ligand 1 expression in EBUS aspirates of non–small cell lung cancer: Is interpretation affected by type of fixation?

“…A growing number of studies have now examined the variability of PD‐L1 expression between different types of NSCLC specimens, which include bronchial washings, aspirates of the primary tumor or its metastases (including cells from pleural and pericardial fluids), endoscopic and transthoracic needle biopsies, incisional biopsies of tumor deposits (usually in skin or superficial lymph nodes), and entire resected tumors . Unfortunately, the specimens compared in these studies have almost always differed not only in their nature (cytology vs histology) but also in their site of origin, and the well‐documented heterogeneity of PD‐L1 expression within and between tumor deposits has made the precise basis of any variability difficult to determine.…”

“…Although much has now been published about the variability of PD‐L1 expression between different types of specimens of NSCLC, little attention has been paid specifically to the important question of the effect of fixation. In view of this, we thought it would be of value to determine whether there is any difference in PD‐L1 expression between EBUS‐guided aspirates of NSCLC fixed in alcohol‐based fixatives and those fixed in NBF, the standard laboratory fixative for histology specimens.…”

Cytology cell blocks from malignant pleural effusion are good candidates for PD-L1 detection in advanced NSCLC compared with matched histology samples

“…MPE samples are easy to acquire, and this type of cell block sample is often used as an alternative or sometimes as the only adequate sample for various relevant tests, such as IHC and molecular testing related to targeted therapy [10,11]. In the past few years, studies on the applicability of small biopsies and cytology samples for PD-L1 IHC detection have become very common [12][13][14][15][16][17][18]. To the best of our knowledge, only few data have been published on the reliability of MPE cell blocks for PD-L1 testing; these studies are limited because of the small sample size of the MPE cell blocks [19,20] or the lack of matched experiments [21,22].…”

PD‐L1 expression in cell‐blocks of non‐small cell lung cancer: The impact of prolonged fixation

“…Interestingly, 22 CBs have been included in the Blueprint (BP) PD‐L1 Immunohistochemistry Comparability Phase 2 Project, which aims to harmonize in real life practice the clinical use of different commercial PD‐L1 IHC assays on 81 routine lung cancer samples 5 . Noteworthy, several studies carried out on matched cytological and histological samples from the same patients have reported comparable results between CBs, surgical resections and small biopsy specimens in terms of adequacy rate, level of PD‐L1 expression, and clinical outcomes 6‐18 . Moreover, CBs also represent a valuable source of diagnostic material even in the early stages of the disease.…”