Dr. O'Donnell on Challenges With PD-L1 Testing in Bladder Cancer

Peter O’Donnell, MD, associate professor of medicine, University of Chicago Medicine, discusses challenges with PD-L1 testing in patients with bladder cancer.

If a patient is cisplatin-ineligible in the frontline setting and is being considered for immunotherapy, PD-L1 testing should be incorporated into their workup, says O’Donnell. However, there are several challenges that remain in testing for the biomarker.

The biggest difficulty is that physicians have 2 FDA-approved diagnostic assays for use in practice and they both have different cut points in how they define the parameters of a positive patient. They also have different algorithms on how to calculate the percentage of positive cells. Moreover, both are linked to an individual drug—one assay is linked to pembrolizumab (Keytruda) use, and the other is linked to atezolizumab (Tecentriq) use. These variances can cause confusion among the medical community, says O’Donnell. If a patient is eligible for one of these therapies, the treating physician should be familiar with how to order each assay and do the proper corresponding scoring, he concludes.