New tissue-preserving therapy for low-risk prostate cancer safe, effective

01/04/17

By Lorraine L. Janeczko

NEW YORK (Reuters Health) - Vascular-targeted photodynamic therapy is safe and effective for low-risk, localized prostate cancer, new industry research suggests.

"To our knowledge, our study is the first prospective comparative trial of the efficacy and safety of focal therapy and the first assessment of active surveillance for prostate cancer in a comparative setting," Dr. Mark Emberton of University College London in the U.K. and colleagues write in The Lancet Oncology, online December 19.

"These findings may potentially give men greater choice," Dr. Emberton told Reuters Health by email. "Men will be able to consider a well-tolerated treatment instead of active surveillance (the standard of care) and the option of tissue preservation instead of surgery or radiotherapy."

The study was designed and funded by Steba Biotech; Dr. Emberton has been a consultant to the company and was paid to participate in the new work.

He and his colleagues compared vascular-targeted photodynamic therapy to active surveillance in an open-label phase 3 randomized controlled trial involving men with Gleason pattern-3 prostate cancer who had received no previous treatment.

The researchers assigned 206 patients at 47 European hospitals to receive vascular-targeted photodynamic therapy, consisting of 4 mg/kg padeliporfin administered intravenously over 10 minutes, with optical fibers inserted into the prostate to cover the desired treatment zone, followed by laser activation for about 22 minutes. Another 207 patients were assigned to receive active surveillance.

At month 24, disease progression was found in 58 (28%) men in the photodynamic therapy group and 120 (58%) men in the active-surveillance group (adjusted hazard ratio, 0.34; p<0.0001).

Among the men receiving photodynamic therapy, 49% had a negative prostate biopsy result versus 14% of those on active surveillance (adjusted risk ratio, 3.67; p<0.0001).

Vascular-targeted photodynamic therapy was well tolerated and sexual and urinary functions were similar between the groups. The most common grade 3-4 adverse events were prostatitis (three cases in the therapy group and one case in the surveillance group); urinary retention (three cases and one case); and erectile dysfunction (two cases and three cases).

In the therapy group, the most common serious adverse events was urinary retention (15 cases, three severe); in the surveillance group, it was myocardial infarction (three cases).

Dr. Emberton told Reuters Health that the good safety profile was a "most reassuring" surprise, as this was the first time that the treatment was provided at non-expert centers.

Dr. Soroush Rais-Bahrami, co-director of the UAB Program for Personalized Prostate Cancer Care at the University of Alabama at Birmingham, told Reuters Health by email, "This study provides an important basis for new focal approaches to treating prostate cancer, particularly in the era of advanced imaging and improved localization and risk stratification of men who may be safe and suitable for focal therapy options."

Dr. Rais-Bahrami, who was not involved in the study, added that the financial and quality-of-life aspects of the new treatment should also be evaluated.

In an accompanying editorial, Dr. Stephen J. Freedland of Cedars-Sinai Medical Center in Los Angeles says the results do not justify routine use of vascular-targeted photodynamic therapy for all men with low-risk prostate cancer.

"First, for men with very low-risk versus low-risk prostate cancer, the risk of progression is very low," he writes. "For these men, the benefits of early treatment, even a less toxic treatment, are hard to justify. Second, for men with higher-risk disease, but still low risk, in whom the risk of progression is higher, upfront aggressive treatment should be considered."

"Third," Dr. Freedland adds, "although still rapidly evolving, with modern imaging (ie, MRI), genomic testing, and imaging-based biopsies, we can better risk stratify those who need aggressive treatment versus those with such low-risk disease that active surveillance is preferred."

"If these methods had been used," he noted, "men could have been better selected for this trial, reducing the high risk of progression with active surveillance alone, thereby even further lowering the potential benefits of vascular-targeted photodynamic therapy."

Steba Biotech employed or had other financial ties to several of the authors, developed the study protocol, interpreted the data and paid for preparation of the manuscript.

Drs. Freedland and Rais-Bahrami stated that they have no conflicts of interest.

SOURCE: bit.ly/2hQCTKg and bit.ly/2iCZg2X

Lancet Oncol 2016.

(c) Copyright Thomson Reuters 2017. Click For Restrictions - http://about.reuters.com/fulllegal.asp