Green Cross’ Elaprase Challenger Moves Ahead In US
This article was originally published in PharmAsia News
Executive Summary
Following a robust performance in the domestic market, Green Cross' Hunterase, the closest potential competitor to Shire's Hunter syndrome drug Elaprase, is set to enter mid-stage clinical trials in the US on its way to the world's biggest market with possible dosing and pricing advantages.
SEOUL - Green Cross Corp., a leading South Korean biopharma firm, has received approval from the US FDA to begin a Phase II clinical trial with Hunterase (idursulfase beta), paving the way for only the world’s second Hunter syndrome drug to enter the biggest global market.
The South Korean company's enzyme replacement therapy for the rare lysosomal storage disorder received domestic regulatory approval as an orphan drug in 2012 on the basis of a Phase II study.
That approval was supported by a trial comparing Hunterase with Shire PLC's commercialized drug Elaprase (idursulfase) that was conducted in collaboration with the Samsung Medical Center in Seoul, in which Hunterase reduced the excretion of urinary glycosaminoglycans by 30-40%.
At present, Hunterase holds more than 50% of the South Korean market for its indication, while the remained is held by Elaprase. Last year, sales of Hunterase exceeded KRW20bn ($17.4m), including exports to South America and North Africa.
Like Elaprase, Hunterase is a recombinant version of the iduronate-2-sulfatase enzyme that is lacking in patients with Hunter disease, also known as mucopolysaccharidosis type II.
The inherited genetic disorder, which predominantly affects males, has an estimated incidence of one in 100,000-150,000, and affects the body's ability to break down mucopolysaccharides known as glycosaminoglycans (specifically dermatan sulfate and heparan sulfate). The build-up of these leads to a range of life-threatening problems including stunted development, skeletal and facial deformities, infections, impaired CNS and mental ability and declining cardiac function.
Patient populations of the rare disease stand at about 70 in South Korea, 500 in the US and 2,000 worldwide. The global market for Hunter syndrome therapies, currently estimated at KRW600bn, is expected to grow to KRW1tn in the coming years.
Cost, Dose Advantages?
With a total cost of several hundred thousand dollars per year, Elaprase - which was launched in the US in 2006 and Europe in 2007 - is one of the most expensive drugs ever commercialized.
In South Korea, the reimbursement price of Hunterase is KRW2.28m per 3ml vial, below that of Elaprase’s roughly KRW2.65m.
During the planned US Phase II study, Green Cross will explore the efficacy and safety of Hunterase when its dosage is doubled to 1mg/kg or tripled to 1.5mg/kg in comparison to the standard 0.5mg/kg. In South Korea, Hunterase was approved in the same dosage as Elaprase (0.5mg/kg).
If the study confirms that Hunterase can be administered at these higher dosages, this may confer improved efficacy over Elaprase and would establish Hunterase's superiority over the competing drug, Green Cross noted. "Conducting clinical trials in the US is significant for Hunterase's entry into global markets," said Eun Chul Huh, president of Green Cross.
After completion of the Phase II study in the US, the company may proceed with the regulatory approval process or move on to a global Phase III study, said an official at Green Cross. "We will initially aim to launch the drug in the US and then enter other major global markets including Europe," said the official.
Hunterase won US FDA orphan drug designation in February 2013 (Also see "Korea’s Green Cross Receives U.S. FDA Orphan Drug Status For Elaprase Biobetter" - Scrip, 22 Feb, 2013.), while Elaprase lost its orphan exclusivity in July that year.
New Formulations?
Green Cross is also conducting follow-up studies for Hunterase to diversify administration routes, and plans to soon begin trials in Japan designed to improve the brain disease of Hunter syndrome patients.
According to BioMed Tracker
, several other companies including Sangamo BioSciences Inc. and Esteve SA are conducting preclinical and clinical trials for Hunter syndrome therapies.
As part of an internationalization strategy, Green Cross is also poised to enter major global markets with its plasma-derived products. In January this year, the US FDA accepted for review the company’s biologics application for IVIG-SN (human normal immunoglobulin G for intravenous administration) intended for the treatment of primary immunodeficiency diseases.