Otsuka’s Samsca has been approved in Japan as a treatment for a rare genetic form of kidney disease.
Samsca (tolvaptan) is the first approved treatment anywhere in the world for autosomal dominant polycystic kidney disease (PKD), which is characterised by the proliferation of fluid-filled cysts in the kidneys and progression to end-stage renal failure.
Treatment with Samsca has been shown in trials to reduce the progression of renal failure by around 50 per cent, providing a treatment option for the approximately 30,000 people in Japan have this form of PKD.
Samsca is also under regulatory review for PKD in Europe but hit a hurdle in the US last year when the FDA – on the advice of an advisory committee – declined to approve the drug without additional evidence of its clinical benefits.
The drug is a first-in-class vasopressin V2-receptor antagonist and is already sold in a number of countries for the treatment of low blood levels of sodium (hyponatraemia), which can be caused by conditions such as organ failure and pneumonia.
Sales for hyponatremia are modest but growing quickly – expected to rise more than 70 per cent to reach around 20bn yen ($195m) in the current fiscal year, and an extension of the license to include PKD could lend additional growth momentum. The drug is also in phase 3 testing as a treatment for oedema in cardiac patients and in phase 2 for oedema in cancer patients.
Meanwhile, Japan’s Ministry of Health, Labor and Welfare (MHLW) has also approved:
• Astellas and Medivation’s oral androgen receptor inhibitor Xtandi (enzalutamide) for the treatment of patients with castration-resistant prostate cancer (CRPC). The drug has already been launched in the US and Europe as a second-line therapy for CRPC. The Japanese approval prompts a $15m milestone payment from Astellas to Medivation.
• AstraZeneca’s SGLT2 inhibitor Forxiga (dapagliflozin) for diabetes. The drug, which will be co-promoted in Japan with Ono Pharmaceutical, is the second drug in the fast-growing new therapeutic class to reach the market in Japan after Astellas’ Suglat (ipragliflozin). It is already on the market in the US and Europe.
• Takeda’s Zacras (azilsartan and amlodipine), a fixed dose combination therapy for hypertension. Takeda launched azilsartan as a monotherapy under the Azilva brand name in Japan in 2012, but has opted not to launch it in Europe after re-assessing the market opportunity for the drug.