Good Overall Agreement Among Three PD-L1 Diagnostic Assays Interview with:

Marianne J. Ratcliffe, PhD Associate director of diagnostics AstraZeneca Alderley Park, UK

Dr. Mariann Ratcliffe

Marianne J. Ratcliffe, PhD
Associate director of diagnostics
Alderley Park, UK What is the background for this study?

Dr. Ratcliffe: PD-L1 status is informative when considering monotherapy treatment and of growing importance when we consider that treatment decision will, in the near future also include combination therapy, an area of focus for AstraZeneca. The Ventana SP263 test has been developed with AstraZeneca, to support selection of PD-L1 testing within the Durvalumab programme, with full analytical validation at a 25% cut point derived from clinical data indicating this cut point best identifies patients more likely to respond to Durvalumab. The Ventana SP263 assay is commercially available in the US and the EU as a Class I device. The Dako 22C3 test has been approved as companion diagnostic for Pembrolizumab, and the Dako 28-8 has been released as a complementary diagnostic as an aid to physicians considering treatment with Nivolumab. What we didn’t know before our study was whether the three assays identify the same patients, and particularly how to cross compare patients identified with the different cut points specified for the different assays. It was therefore an important question to be addressed through a very thorough scientific assessment. What are the main findings?

Dr. Ratcliffe: Our data, generated in 500 commercial samples, demonstrates that three commercially available PD-L1 tests achieved overall percentage agreement of >90%. This was achieved at multiple assay cut-offs. These results indicate that it may be possible to extrapolate the results from one test to that of another test. Further work is required to confirm this finding. What should clinicians and patients take away from your report?

Dr. Ratcliffe: PD-L1 expression is not binary: Using definitions such as positive and negative do not provide the detail we need in a complex setting of immunotherapy. It is highly likely that multiple cut-offs will become clinically relevant when making treatment decisions What recommendations do you have for future research as a result of this study?

Dr. Ratcliffe: The data from the  AstraZeneca. study builds optimism that the assays can align and be interchanged with different algorithms. It is our hope that our data will help the clinical community start a debate on what data set is required to inform practice. AstraZeneca is committed to a personalised healthcare approach in oncology and beyond. We believe that all patients should have access to high quality PDL1 testing to ensure they receive the most appropriate therapy option.


Ratcliffe MJ, Sharpe A, Midha A, et al. A comparative study of PD-L1 diagnostic assays and the classification of patients at PD-L1 positive and PD-L1 negative. Presented at the 2016 AACR Annual Meeting; April 16-20; New Orleans, Louisiana. Poster LB-094

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