Utilization of ctDNA in the EV/Pembrolizumab Setting

Karine Tawagi, MD, of the University of Illinois College of Medicine, describes how she is using ctDNA in her practice in the EV/pembrolizumab setting, and how frequently she is ordering it for her patients.

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Dr. Tawagi: In one of the abstracts presented at the meeting today, we saw some data on ctDNA for metastatic urothelial carcinoma for chemotherapy alone or immunotherapy alone. We saw that patients on chemotherapy had a quicker decline of their ctDNA. However, patients that had a response of ctDNA down-trending with immunotherapy had more meaningful long-term clinical responses. We also saw that ctDNA going down was associated with improved response rate, improved PFS, and improved OS.

In terms of how I’m using it, I am obtaining it (not based on any data in the EV/pembrolizumab world) as an adjunct to our imaging. Some providers may choose to do it every 3 weeks with the day 1 of every cycle, or every 6 weeks. In general, for metastatic urothelial cancer, we are doing imaging every 3 months. Perhaps we just want a touch point to see how the ctDNA is looking, to help as an extra point of guidance in terms of dose adjustments, if necessary, with EV. If we see toxicity, and if it is rising rapidly, that may be a reason to repeat imaging a little bit sooner.

View her continued comments.