Currently Viewing:

Study Finds Need for Standardization of Immune Checkpoint Inhibitor Assays in NSCLC

Alison Rodriguez
The development of immune checkpoint inhibitors, including programmed death-1 and programmed death-ligand 1 (PD-L1) inhibitors, has changed the treatment methods for non–small cell lung cancer (NSCLC). There may be potential interchangeability of the clinical use of certain PD-L1 inhibitors on tumor cell membranes for NSCLC, but not for assessment of PD-L1 expression on immune cells, according to a study.

In a study, published by the Journal of Clinical Oncology, reviewed previously published studies from January 2016 to January 2017 on clinical trial and laboratory-developed PD-L1 immunohistochemistry (IHC) assays (LDAs). The researchers analyzed the effects of diagnostic methods on PD-L1 expression levels in the studies in order to address the practical issues related to tissue samples.

Use of pembrolizumab to treat NSCLC requires PD-L1 IHC testing, but nivolumab and atezolizumab are approved without testing. However, the FDA has approved complimentary PD-L1 tests for both.

“Although PD-L1 IHC testing has value as a biomarker, it has limitations. Research is ongoing to identify novel biomarkers that could be used alone or in combination with PD-L1 expression levels to improve patient selection for immunotherapy,” the researchers concluded.

Following the review, the researchers found that high concordance and interobserver reproducibility were present with the PD-L1 IHC 28-8 pharmDx, PD-L1 IHC 22C3 pharmDx, and Ventana PD-L1 SP263 clinical trial assays for PD-L1 expression on tumor cell membranes. For lower PD-L1 expression was detected with Ventana PD-L1 SP142. Additionally, immune-cell PD-L1 expression was variable and interobserver concordance was poor. Researchers also noted the variable effects on PD-L1 expression for inter- and intraturmoral heterogeneity.

The researchers suggested that the development of LDAs requires standardization before they are used for recommendations in routine clinical use. In addition, the authors noted a need for training or specialized pathologists.

“Interpretation of PD-L1 IHC assays differs from most other IHC assays in the need for appreciation and understanding of the often-heterogeneous morphology of pulmonary tumors,” the authors noted. “Therefore, specialized training is important to maintain consistency and quality of interpretation between pathologists.”

Copyright AJMC 2006-2018 Clinical Care Targeted Communications Group, LLC. All Rights Reserved.
Welcome the the new and improved, the premier managed market network. Tell us about yourself so that we can serve you better.
Sign Up

Sign In

Not a member? Sign up now!