In Significant Reversal, Prostate Drug Met Primary Goal After All

Xconomy San Diego — 

After getting something worse than a lump of coal for Christmas last year, Sophiris Bio got an early present for the 2015 holidays— its experimental prostrate drug met the primary goal of a late-stage study. Shares of Sophiris Bio (NASDAQ: SPHS) more than quadrupled overnight—opening today at $3.28 from yesterday’s close of 86 cents a share.

Last December, shares of Sophiris, based in San Diego and Vancouver, BC, plunged more than 80 percent after the company reported interim results, saying the experimental drug failed to meet a pre-defined threshold of efficacy after three months.

But that was then.

In final results following the 52-week pivotal trial, Sophiris says its drug candidate topsalysin demonstrated a statistically significant improvement among men experiencing lower urinary tract discomfort following a single treatment with the drug. Sophiris has been developing topsalysin as a therapy for treating an enlarged prostate, also known as benign prostatic hyperplasia, (BPH).

Topsalysin is a genetically altered form of the naturally occurring protein proaerolysin. Sophiris says BPH affects most men in their 60s. As the prostate enlarges, the walnut-size gland gradually press against the urethra, leading to an unhappy condition that requires frequent urination or difficult urination. Standard drugs or surgery can lead to erectile dysfunction or cardiovascular side effects.

In a statement today, Sophiris says “the drug continues to demonstrate a favorable safety profile, with no evidence of any treatment related sexual or cardiovascular side effects.”

Sophiris shares settled after the opening, and were hovering above $2.50 in mid-day trading.

How did things turn around so dramatically for Sophiris?

“The thing that’s important to understand about the interim analysis is that it wasn’t a true interim analysis,” Sophiris CEO Randall Woods told me by phone this morning. Rather, the interim results were intended to serve as a snapshot of how well the clinical trial was meeting a pre-defined efficacy threshold after three months, as determined by an independent data monitoring committee.

If the trial met the efficacy threshold at three months, Sophiris intended to proceed with laying the groundwork for another late-stage trial, Wood said. In other words, the interim results “really were for our own internal planning purposes.”

With the positive final outcome reported today, Woods said Sophiris would begin planning for that late-stage trial, which would be needed for the company to seek regulatory approval of the drug. To complete the trial, Sophiris would need to raise additional capital or find a big pharma partner, Woods said.

Sophiris COO Allison Hulme, who oversees research and development, says a final analysis found that patients who received the drug began showing improvement in their urinary discomfort in week eight, but the maximal effect was around the 18th week of the study. “The analysis showed us a good [almost] 8 point improvement [using the International Prostate Symptom Score] that was maintained through the rest of the study,” Hulme said.

Sophiris has genetically modified proaerolysin so that it can be activated by only one enzyme—the Prostate Specific Antigen (PSA), which is found only on the surface of prostate cells and nowhere else in the body.

The drug is deposited by an ultrasound-guided injection in the area where the prostate meets the ureter. Once activated by PSA, the protein drills into the prostate’s cell walls, triggering a programmed cell death known as apoptosis—a process that shrinks the prostate without affecting the ureter or surrounding tissues.