Dr. Siefker-Radtke on PD-L1 as a Biomarker in Bladder Cancer

Arlene O. Siefker-Radtke, MD, associate professor, Department of Genitourinary Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, clinical co-leader, Bladder SPORE Executive Committee, discusses why researchers and physicians should reconsider the utility of PD-L1 as a biomarker for patients with bladder cancer.

PD-L1 hasn’t been a good marker for patients with urothelial cancer, she explains. There have been hints in some clinical trials that the response rate might be improved when looking at the PD-L1 expression on the immune infiltrate in addition to PD-L1 expression on the tumor cell.

However, response rates in PD-L1—negative tumors are higher with immunotherapy than single-agent taxane. PD-L1 is a very dynamic biomarker, she says, adding that it can be upregulated in patients who have had chemotherapy, BCG when given intravesically, or treatment with a PD-L1 inhibitor. Researchers have not yet had concrete data showing not to consider checkpoint inhibition when PD-L1 is low, because some patients still respond to such treatment.

At the moment, Siefker-Radtke says that she cannot recommend PD-L1 expression as a must-have biomarker because patients who don’t have it may still have benefit, may still respond, and may even have long-term durable responses that improve their overall survival.