Idorsia sheds surplus DMD therapy to Santhera

Santhera has agreed to purchase a sublicense to Duchenne muscular dystrophy (DMD) drug vamorolone, originally developed by ReveraGen, from fellow Swiss biotech and Actelion spinout Idorsia.

The company has also announced a $50 million share placement next month that will cover a $20 million upfront fee to Idorsia to claim its rights to the mid-stage candidate—which cover all markets apart from Japan and South Korea—as well as fund further clinical development.

Vamorolone is billed as a first-in-class ‘dissociative’ steroid that couples the anti-inflammatory efficacy of steroid drugs—used to treat DMD in around half of all patients with the disease—but lacks the safety issues with these drugs which include weight gain and slow growth in children linked to bone and muscle side effects.

According to ReveraGen, vamorolone binds to glucocorticoid receptors just like regular steroid drugs, but modifies their downstream efficacy to minimize ‘transactivation subactivity’ that affects bone structure and function and can cause muscle atrophy. Muscle weakness is the main feature of DMD, so sidestepping that effect is particularly important in these patients.

Vamorolone has already cleared a phase 2a study which according to biomarkers backed its gentler profile, and it is now in a 120-patient pivotal trial run by ReveraGen in Europe that is due to read out in 2020. It slots into Santhera’s pipeline alongside phase 3 DMD candidate idebenone, which is already sold as Raxone for a rare degenerative eye disease.

If approved, it would be a rival to PTC Therapeutics’ Emflaza (deflazacort), which was the first steroid to be FDA-approved for DMD. It was launched by Marathon Pharma last year with an $89,000 annual price tag that drew fierce criticism from policymakers, including Sen. Bernie Sanders, who has just submitted a price control bill in the Senate.

Marathon swiftly passed the rights to Emflaza to PTC for $190 million shortly afterwards, and the latter introduced weight-based pricing that comes in at around $35,000 for a 25 kg child. That’s still well above the $1,000-per-year price tag for generics of the drug in other countries and, according to some commentators, could actually make the drug more expensive than Marathon’s initial price for some patients.

Commercial considerations for vamorolone are still some way off of course, and if it is shown to reduce steroid side effects and maintain in trials, it will be a much-needed therapeutic alternative for patients.

As part of the proposed deal, Idorsia—which was created when Johnson & Johnson bought Actelion for $30 billion last year—is getting a million shares in Santhera, making it the largest shareholder with a 13.3% stake.

Idorsia’s CEO Jean-Paul Clozel said that with four drugs already in late-stage clinical development “we have decided to hand the option to license vamorolone to Santhera because they are ideally placed to maximize the potential of this asset.”