Reata acquirer, Biogen, has licensed ex-North American rights to Stoke's zorevunersen, a proposed treatment for the neurodevelopmental disorder, Dravet syndrome. (1,2,3)
Some notable aspects of the deal:
Zorevunersen is Stoke Therapeutics’ lead asset. It is due to commence testing in Phase 3 next quarter.
Stokes’ other neurodevelopmental assets (all antisense oligonucleotides) are still at pre-clinical stage and all are encumbered. In January 2022, Acadia acquired global rights to two assets (for Rett syndrome and an undisclosed indication). Acadia will be responsible for clinical development and commercializationof these two assets and agreed to a 50:50 collaboration to develop and commercialize a drug for a third indication, SYNGAP1.
There are already drugs approved specifically for Dravet syndrome but these only address the severe epilepsy related to the disease. These drugs are Epidiolex (Jazz Pharmaceuticals) and Fintepla (UCB). GW Pharma, which developed Epidiolex, the first approved drug for Dravet, was acquired by Jazz for up to US$7.2bn in 2021. (4) Zogenix, which developed the repurposed drug, Fintepla, was acquired by UCB in 2022 for up to US$1.9bn (5).
In addition to Epidiolex and Fintepla, multiple other anti-epileptic drugs are prescribed for Dravet. These are all oral treatments, whereas zorevunersen is dosed intrathecally every 4 months.
Although Stoke is aiming to demonstrate improved seizure reduction on top of SOC, the key point of difference for zorevunersen is that it has also demonstrated improvement in cognition and behaviour (measured by Vineland-3 GSV scores).(6)
It is estimated that there is a 16,000 Dravet syndrome patient population in the EU4 (Germany, France, Italy and Spain) + UK and 7,000 in Japan. The US population is estimated to be 16,000.(6)
Under the terms of the deal, Stoke will receive an upfront payment of US$165 million. Stoke will continue to lead development. External clinical development costs for zorevunersen will be shared (70% Stoke, 30% Biogen). In addition, Stoke may receive up to US$385m in development and commercial milestone payments. Stoke will also be eligible to receive tiered royalties ranging from low double digits to high teens on net sales in the Biogen territory.
Biogen has also acquired an option to license rights outside North America (US, Canada and Mexico) to certain future follow-on ASO products targeting SCN1A (the gene targeted by zorevunersen in Dravet syndrome), in exchange for separate milestone, cost sharing, and royalty considerations.
The Head of Development at Biogen said that the Stoke collaboration broadens Biogen’s late-stage pipeline with the addition of a Phase 3-ready disease modifying therapy and allows the company to leverage its rare disease product commercialization expertise and global footprint.
Some thoughts:
Biogen has yet again demonstrated its appetite for late-stage, rare, neurodevelopmental assets.
Earlier this month, Biogen CEO, Chris Viehbacher, said that he wasn’t keen on taking a lot of risk on Phase 3 clinical trials because “that gets expensive”. Here he has locked up ROW rights for a Phase 3 asset for US$165m, left development and regulatory responsibility to Stoke and limited further risk to 30% of external clinical development costs.(7)
Viehbacher has also put a spoke in the wheel for Acadia, if it had ambitions to acquire Stoke. A Stoke acquisition is something that has been suggested by analysts and Stoke currently has a market cap less than half of Neuren.
Jon Pilcher has previously said that he would not sell US licensing rights for NNZ-2591 as was done for trofinetide. But outlicensing other territorial rights has not been ruled out.
There is a possibility (though low, I think) that Dravet syndrome could be one of the further proposed indications for NNZ-2591.
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