Sophiris Bio to press on to Ph III despite mixed data for topsalysin in Ph IIb

US biotech firm Sophiris Bio (Nasdaq: SPHA) has released mixed Phase IIb study results of topsalysin for localized prostate cancer, including top-line safety and biopsy results from the patients who received a second administration of study drug, which appeared to be safe and generally well-tolerated.

Based on the top-line review of the six-month biopsy results following the second administration of topsalysin, the company has concluded that there appears to be no additional clinical benefit gained with a second administration. The decision to include a second administration of topsalysin in any future clinical studies is under review by the company, whose shares plunged 40.29% to $1.23 on the news.

As previously stated, a total of 27% of patients (10/37) demonstrated a clinical response six months following a single administration of topsalysin. Six of the 10 clinical responders experienced a complete ablation of their tumor. Based on these results, the company is moving forward with its plans to propose a single Phase III registration trial design using a single administration of topsalysin, which it will discuss with regulatory agencies in the coming months.