GW Still Sees Future For Sativex In US
MS Spasticity Drug Struggling in Europe
Executive Summary
The UK firm is starting an additional Phase III trial of 450 patients to supplement positive data from the three European Phase III trials it has already concluded in a bid to convince the FDA of Sativex's potential.
While the main focus at GW Pharmaceuticals PLC is on growing its epilepsy seizure drug Epidiolex, the company is looking to kickstart its multiple sclerosis spasticity therapy Sativex, an older cannabis-based drug that has failed to have much impact since its first approval back in 2005.
Sativex (nabiximols) is an oromucosal spray that contains delta-9-tetrahydrocannibinol (THC) and cannabidiol (CBD). Since its first thumbs-up in Canada over 14 years ago, it is now approved in over 25 countries for MS spasticity, following a spate of approvals in Europe from 2010.
GW does not market Sativex but has licensing agreements in Europe, Canada, Israel, Mexico, and South America with Bayer AG and Almirall SA. However it has not exactly proved to be a cash cow and GW's third-quarter 2019 results revealed that net sales of Sativex were just $2.8m.
The company told Scrip that the sales figure was based on GW selling Sativex to its commercial partners. There are provisions for milestone and royalties "but these are only listed when receipt of these payments become certain and there’s no risk of revenue reversal."
Sativex has struggled to get reimbursed in Europe. As recently as August 2019, NICE, the health technology assessment body for England and Wales, has issued a new draft guideline reiterating previous guidance from 2014 which told doctors not to prescribe Sativex for spasticity in MS because it is not a cost-effective treatment. (Also see "UK’s NICE Not Convinced By Cannabis-Based Medicines " - Pink Sheet, 9 Aug, 2019.)
The guideline also said that cannabis-based medicinal products should not be used to treat spasticity except as part of a clinical trial. The NICE committee stated in August that "there were reductions in some measures of patient-reported spasticity and no difference in adverse events in the treatment or placebo groups although much of the evidence was assessed as low quality."
NICE agreed that the longer-term benefits of the THC/CBD spray "are likely to outweigh any potential harms, although it was not clear how benefits related to improvements in quality of life.”
The prospects for Sativex across the Atlantic also looked grim a couple of years ago. In December 2017, after three Phase III failures looking at expanding the drug into cancer pain, long-time partner Otsuka Pharmaceutical Co. Ltd. decided to hand back the US rights. The companies first linked up in 2007, when Otsuka agreed to pay an $18m upfront fee and up to $273m in potential milestones in exchange for an exclusive license to develop and market Sativex in the US. (Also see "Interview: GW Pharma Gears Up For Pivotal 2018" - Scrip, 12 Dec, 2017.)
However, since getting back the rights from Otsuka, GW has been advancing plans for Sativex in the US and on the firm's Q3 call, chief medical officer Volker Knappertz said "we see this product as a major late-stage pipeline opportunity with potential for extended exclusivity."
He claimed, "We have spent the last several months evaluating the development strategy and commercial potential for Sativex across a range of neurological and psychiatric indications." First up, and "based on an ongoing dialogue with the US Food and Drug Administration," GW's plan is to perform one additional Phase III trial of approximately 450 patients starting in the first quarter to supplement positive data from the three European Phase III trials it has already carried out.
Knappertz said the new trial was “intended to address the FDA's preference for a primary endpoint that focuses directly on the physical manifestations of spasticity. To complement this trial, GW is also initiating two mechanistic studies of about 35 patients each, so "we have a comprehensive data package in place together with over 80,000 patient-years of safety data," he added.
Over 35% of MS patients have moderate to severe spasticity and represent candidates for this treatment, Knappertz said. Discussions with MS experts in the US have revealed an appetite for Sativex, he added, "in a space where there continues to be a substantial need for new therapies as there have been no new oral anti-spasticity treatments introduced for over 20 years."
Knappertz said that during 2020 and 2021, GW hopes to initiate clinical programs in additional follow-on indications for Sativex. "We see a truly exciting opportunity for this product to address market needs in several indications over the coming years."
His enthusiasm was shared by analysts at SVB Leerink. In an investor note on 6 November, they said the spray "receives minimal attention, but we believe it could become a $380m drug in 2029 in terms of global sales."