Case Study: Pseudoprogression in Urothelial Cancer

Arlene O. Siefker-Radtke, MD:One thing that I have noticed, and it’s really interesting to observe this: Are patients experiencing pseudoprogression? Pseudoprogression has been reported with single-agent immunotherapy, although in honesty, I have not observed dramatic pseudoprogressions in that disease state. With a combination of bempegaldesleukin plus nivolumab, we see a proliferation of a lymphocyte population in the peripheral blood, and also in the tissues of tumor for patients treated with this combination. So it was not, in a way, too surprising to see patients who had evidence of pseudoprogression as well.

If you look at the slides provided, this is a patient of mine whose tumor obviously grew. It clearly met disease progression by RECIST criteria [in] not only the overall tumor size but even as the solid component of the tumor appeared to increase in size.

What was notable to me was the lack of symptoms this patient experienced. In fact, they felt better and were frankly surprised by the lack of response given the improvement in their clinical symptoms. The lack of worsening clinical symptoms does appear to be a potential feature helping us determine whether a patient may be a pseudoprogressor.

This patient chose to continue on treatment. We did a biopsy confirming that there was still active cancer, although we did see a lymphoid infiltrate mixed with the tumor. With additional treatment, you can see that this tumor continued to respond despite the initial progression, and the patient remains on this treatment at the time of this presentation.

Transcript edited for clarity.