Renascience Inc. said Japan's Minister of Health, Labour and Welfare designated its experimental drug RS5614 an orphan drug for cutaneous angiosarcoma on September 25, 2026. The rare skin cancer, which arises from malignant blood-vessel-lining cells, has a five-year survival rate below 10% and an incidence of 2.5 cases per million in Japan, a rate the company says is rising.
Paclitaxel is the standard first treatment, but median overall survival remains short, at 649 days, and even when chemotherapy is combined with radiotherapy, lasting tumor shrinkage or disappearance is difficult to achieve in most cases. Options after paclitaxel fails are thin: pazopanib produces a 3% response rate in angiosarcoma, and eribulin shows some tumor response but causes serious side effects in 64% of patients.
In a Phase 2 trial run with Tohoku University Hospital and six other Japanese institutions, among patients whose disease had stopped responding to paclitaxel, adding RS5614 (a PAI-1 inhibitor) to paclitaxel produced a 13.3% response rate (95% confidence interval: 1.7% to 40.5%), an 86.7% disease control rate, median progression-free survival of 4.0 months and median overall survival of 20.8 months. Renascience says those survival figures exceed the 2.8-month progression-free survival and 12.1-month overall survival reported for pazopanib in Japan's JCOG1605 trial, though the two studies were not run head-to-head, and the wide confidence interval around the response rate reflects the small number of patients involved. The company finalized its clinical study report on September 7, matching the results it first disclosed in February. No Grade 5 adverse events, or serious side effects tied to the drug, occurred.
The orphan designation is not drug approval. It adds a pricing premium if RS5614 reaches market, lengthens the post-approval re-examination period that functions as market exclusivity, and makes Renascience eligible for subsidies through Japan's National Institute of Biomedical Innovation, Health and Nutrition. The company is now discussing a Phase 3 trial toward regulatory approval with Japan's Pharmaceuticals and Medical Devices Agency (PMDA). Renascience said the designation does not change its earnings forecast for the year ending March 2027.