The use of a novel focal therapy technique called high-frequency irreversible electroporation (H-FIRE) for the treatment of localized prostate cancer resulted in a 6-month clinically significant prostate cancer (csPCa) rate lower than previously seen with other energy platforms, according to Chinese investigators.
Among the 100 patients who received H-FIRE and were biopsied at 6 months, the 6-month csPCa rate of 6.0% (95% CI 2.2-12.6) established superiority versus a pre-defined historical control rate of 20%, reported Chuanliang Xu, MD, PhD, of Changhai Hospital in Shanghai, and colleagues.
Among the six cases of csPCa, just one was inside the treatment zone, resulting in an in-field csPCa rate of 1%, “suggesting the reliability of H-FIRE,” Xu and colleagues wrote in JAMA Surgery.
They contrasted that result with reported in-field recurrence rates of 1.7-26.0% for cryotherapy, 6-100% for high-intensity focused ultrasound, 8-38.0% for laser ablation, and 17-33.0% for photodynamic therapy.
The primary endpoint of 6-month csPCa was defined as any biopsy core with Gleason score of greater than or equal to 7, or Gleason score of 6 plus maximum cancer core length of greater than 3 mm or an increase from the original cancer burden. Treatment superiority was defined by the upper limit of the 95% CI being less than 20%.
The trial was conducted at four medical centers in China between May 2018 and March 2019. Eligible patients were between the ages of 40 and 85, with low- or intermediate-risk PCa, PSA level less than 20 ng/mL, clinical stage of T2c or less, and Gleason score of 7 or less.
Xu and colleagues also reported that a worst-scenario sensitivity analysis (in which patients who underwent H-FIRE, but did not undergo biopsy at 6 months, were assumed to have csPCa) resulted in a 6-month csPCa rate of 11.0% (95% CI 5.8-18.4), still supporting superiority versus the historical control. The same held true with a subgroup analysis that only included the 57 patients with Gleason score of 7 at baseline, which resulted in a 6-month csPCa rate of 3.5% (95% CI 0.4-12.1).
In addition, the authors found:
- Prostate cancer of any kind in 14 patients (two with a Gleason score of 7, and 14 with a Gleason score 0f 6)
- Median PSA levels of 9.0 ng/mL at baseline and 1.1 ng/mL at 6 months
- Median International Prostate Symptom Scores of 9.0 at baseline and 4.5 at 6 months
- Median International Index of Erectile Function 5 scores of 2.0 at baseline and at 6 months
In an accompanying commentary, Shawn Dason, MD, of the Ohio State University in Columbus, and colleagues suggested that even though there was no appropriate control group for this study, “the methodology for the question the authors sought to answer was reasonable.”
Furthermore, the lack of a control group was likely unimportant given the in-field rate of clinically significant cancer of 1%, Dason and his colleagues observed, adding that while patients with Gleason scores of 6 probably did not need treatment and could have benefited from active surveillance, “results in the remaining cohort are compelling enough.”
As for safety, Xu and colleagues reported no intraoperative complications. During the 6-month follow-up, there was an overall complication rate of 37.6%, with the most common complications being elevated white blood cell level in urine (23.9% of 109 patients), followed by epididymitis (4.6%), prolonged gross hematuria (3.7%), urinary retention (2.8%), urinary tract infection (1.8%), and bladder stones (0.9%).
The authors acknowledged that major limitations of the study included the use of a historical control rather than a parallel control group, as well as its relatively small sample size. Thus, “trials that compare H-FIRE with thermal energy platform directly using a larger sample size are needed to verify our preliminary findings,” they observed.
In their commentary, Dason and his colleagues wrote that the data presented in the study “are reasonable in demonstrating histologic efficacy of the ablation technique they studied.”
“Nonetheless, the broader clinical questions essential to establish focal therapy for prostate cancer remain unanswered — namely in whom is this therapy oncologically effective and how should we define oncologic efficacy?” they added. “Answering these questions will ultimately be critical in supporting focal therapy for prostate cancer as a standard of care.”
Disclosures
The trial was funded by Remedicine.
Xu and a co-author reported receiving grants from Remedicine.
The editorialists had no disclosures.
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