A one-off injection of stem cells into the penis has restored erectile function in some men undergoing prostate removal surgery—even if they didn’t respond to conventional ED drugs like Viagra.
Erectile dysfunction (ED) is a common side effect of a radical prostatectomy and, while some patients can be treated, a sizable proportion get no benefit from conventional drug therapies. There have been a lot of anecdotal reports that stem cell therapy can be a benefit, but clinical evidence is lacking.
Cytori and investigators in Denmark have tried to provide clinical support for the idea via an open-label phase 1 trial of adipose-derived regenerative cells (ADRC) in 21 patients, including 15 who were urinary-continent after surgery and six who were incontinent.
Based on one efficacy scale—the International Index of Erectile Function-5 (IIEF-5)—Cytori’s therapy achieved a significant improvement in sexual function overall, but was unable to hit that target on the accompanying erection hardness score (EHS) measure. However, there may be an explanation for the result, which comes down to how badly the men were affected after the surgery.
A subset of 15 patients who didn’t develop urinary incontinence after the prostatectomy did even better on the IIEF-5 measure, and also saw a statistically significant benefit on EHS. And among that continent group, more than half (53%) recovered enough erectile function to have intercourse during the course of the 12-month study.
The results throw a lifeline to men who can’t resolve ED problems with oral drugs like Pfizer’s Viagra and Eli Lilly’s Cialis, which are both PDE5 inhibitors, or direct injections with prostaglandin-based drugs into the penis. Where these fail, the last resort for patients is typically a penile implant.
Drug treatments for ED represent are a massive market estimated at around $4.5 billion in 2016, although generic competition is eating into branded product sales, so a one-off stem cell therapy offers an intriguing opportunity.
It’s worth noting, however, that private clinics around the world have been offering stem cell treatments for ED “without preceding rigorous clinical data regarding safety and efficacy,” according to the Danish team led by Martha Haahr Ph.D., of Odense University Hospital.
The new 12-month data reinforce six-month results in 17 subjects reported in 2016, but the authors said their study is limited by being unblinded, which means they can’t rule out a placebo effect or indeed the possibility that the improvements would have happened spontaneously over time.
“The next step before stem cell therapy can be made available to patients is to perform a randomized blinded and placebo-controlled trial among continent men,” they wrote in the paper.
It’s a positive trial for Cytori nevertheless, and comes as the biotech is carrying out another trial to see if ADRC therapy can tackle stress urinary incontinence after radical prostatectomy, another common side effect of this type of surgery. Data from this study, called ADRESU, are due in the first half of 2019.