Feasibility study explores focal therapy plus radiation in prostate cancer

In this interview, Timothy D. McClure, MD, highlights the RTIRE study (NCT05345444), exploring treatment with focal therapy followed by low dose, whole gland radiation in patients with prostate cancer. Overall, the trial plans to enroll 42 patients to assess the feasibility of focal therapy with irreversible electroporation (IRE) in combination with stereotactic body radiation therapy (SBRT).According to the investigators, this combination may provide an optimal treatment option for patients with intermediate-risk prostate cancer.¹

Timothy D. McClure, MD

McClure is an assistant professor of urology at Weill Cornell Medicine in New York, New York.

This transcription has been edited for clarity.

At this year’s AUA, you gave a presentation titled, “Symbiosis of Treatments to Improve Outcomes on Focal Therapy”. Could you highlight some of the key take-home messages from that session?

This was a talk I gave during the Focal Therapy Society meeting. There's obviously a huge interest in focal therapy for prostate cancer, largely because we want to try to prevent the overtreatment of prostate cancer and also develop better approaches to deliver high-quality treatment options for patients. The issue with focal therapy, however, is there's recurrence. Focal therapy is the concept where you treat just 1 part of the prostate, specifically with ablation techniques such as focal cryoablation or IRE. Then you follow the remaining prostate that doesn't have cancer at the time of the initial treatment, and you hope that the patients can avoid definitive treatment in the future. The downside to it is that some studies [show that] 40% of patients will have recurrence in the prostate after having focal therapy, which is not great.

My talk highlighted a clinical trial I am running that addresses this limitation to focal therapy.This trial, called RTIRE, is combining focal therapy, specifically IRE with low dose whole gland radiotherapy. In the trial we treat just the area of cancer that we can see on an MRI. Then after focal IRE, patients undergo 2 session of low-dose, whole gland radiation. We hypothesis that this will sterilize the remaining prostate and reduce the recurrence rate.

Could you expand on some of the initial outcomes were that were presented at the meeting?

We discussed the first 10 patients in this trial and reported on patient-reported outcomes with regards to sexual and urinary function as well as 1 year biopsy results. The large majority of those patients returned to baseline with regard to their sexual function and urinary function. We also reviewed the PSA kinetics, which mimic that which is seen with patients undergoing standard of care higher dose radiation. Our 1 year post-treatment biopsies have been negative to date, suggesting that the combined treatment effect does provide good oncologic efficacy, assuming that a biopsy at a year is a good surrogate for oncologic efficacy. But, at least in short-term, it is encouraging.

What are the next steps planned with this study?

This trial is nearing completion. However, we are planning on moving on to a randomized control trial comparing this novel approach to stand of care radiation therapy.

Reference

1. Radiation Therapy and IRreversible Electroporation for Intermediate Risk Prostate Cancer (RTIRE) (RTIRE). ClinicalTrials.gov. Last updated December 20, 2023. Accessed June 13, 2024. https://clinicaltrials.gov/study/NCT05345444