Management of Advanced Non–Small Cell Lung Cancer - Episode 9

PD-L1 Testing in NSCLC

The pros and cons of conducting PD-L1 testing in patients with non-small cell lung cancer.

Hossein Borghaei, DO, MS: As far as PD-L1 testing, I’m pretty sure I know how it is at your center because we have very similar systems. But that’s much simpler testing. That’s immunohistochemistry [IHC], which has been around for a very long time. It’s easy to incorporate into pathology workflow for the most part. I don’t know what you think, Charu, but in my view, the uptake of PD-L1 testing was a lot faster than the uptake of any other biomarker, and certainly all the DNA markers. And we can understand that. Obviously, molecular testing is a little more complicated, but IHC has been well incorporated into everything we do. How do you see the data, and what do you think about the uptake of PD-L1 testing?

Charu Aggarwal, M.D., MPH: Yes, and I’d like to add that, as opposed to genomic testing or genotyping, where we tend to restrict it, at least in the pure sense, to nonsquamous or to increase it to potentially never-smokers with a squamous cell histology, we look at PD-L1 across all non-small cell lung cancers, irrespective. It’s very important for us in squamous as well as nonsquamous histology. This is maybe one of the few solid tumors where we’re still using PD-L1 testing of the tumor cells to determine which therapy to administer. We’re not doing that for diseases such as bladder cancer anymore, but it remains very important.

Based on the local availability, it’s a simple stain that can be performed relatively quickly. Many institutions adopted reflex pathways, where as soon as a diagnosis of non-small cell lung cancer is made, regardless of histology, slides are prepped for this additional immunohistochemistry stain, and a PD-L1 result is usually available in two to three days or less. It’s made a huge difference, but it also confuses things, because I’ve seen that treatment decisions will be made based on PD-L1 alone. Based on the heavily commercialization around immunotherapy or direct-to-consumer advertising, patients are asking for it. And I find that if PD-L1 is reported before everything—it should be reported—but it’s more of an issue of it shouldn’t be the sole biomarker that’s used to make a treatment decision. I find that trigger is pulled sometimes quicker than I’d like. These are all good. We need all of these tests to be able to make a treatment decision. The more information we have, the better informed we'll be.

Transcript edited for clarity.