Genentech’s IL-6 Inhibitor Bags FDA Approval for Neuromyelitis Optica Spectrum Disorder

On August 14th, Genentech announced the USFDA approval for Enspryng (satralizumab-mwge), the first subcutaneous treatment for adults living with AQP4 positive NMOSD.

By T. Chakraborty, Ph.D.

Neuromyelitis Optica Spectrum Disorder (NMOSD), also known as Devic disease, is a chronic disorder of the brain and spinal cord resulting in inflammation of the optic nerve and the spinal cord, leading to blindness, muscle weakness, and paralysis. NMOSD is known to be associated with anti-aquaporin-4 (AQP4) antibodies that damage astrocytes resulting in inflammatory lesions. Globally, NMOSD affects approximately 10 per 100,000 people and is common among women in their 30s and 40s.

Additionally, African or Asian descent individuals are vulnerable to this disease. Although the majority of the NMOSD cases can be confirmed through diagnostic tests, patients are often misdiagnosed with multiple sclerosis due to overlapping symptoms and relapse-conditions of the disease [1].

FDA Approval

Levi Garraway, M.D., Ph.D., Chief Medical Officer and Head of Global Product Development, said, “Today’s FDA approval of Enspryng, the first subcutaneous NMOSD treatment using novel recycling antibody technology, builds upon the work we’ve done in multiple sclerosis with Ocrevus to develop first-in-class medicines and further the scientific understanding of neuroimmunological diseases. We thank the NMOSD community, including patients and investigators who participated in Enspryng clinical trials.”[2]

Professor Jeffrey Bennett from the University of Colorado, and investigator for the Enspryng trials, added, “For people with NMOSD, relapses can cause devastating, irreversible and disabling neurological effects. Having an approved therapy that can be administered subcutaneously in the home and has demonstrated an impact on the frequency of relapses is an important advancement for patients.”[2]

Enspryng, a Humanized Monoclonal Antibody

Enspryng is the sole approved therapy for NMOSD and works by inhibiting interleukin-6 (IL-6) receptor activity. Additionally, Genentech designed the treatment by using novel recycling antibody technology, which allows for longer antibody circulation as compared to the conventional technology. Enspryng can be administered to the patient once every four weeks after the initial dose by caregivers or by the patient living with NMOSD.

Victoria Jackson, founder, The Guthy-Jackson Charitable Foundation commented, “We are very optimistic the addition of this newly approved treatment option will make a meaningful difference for those living with NMOSD, those who love and support them and the doctors who treat them. When my daughter was diagnosed with NMOSD in 2008, there were no approved treatment options and a critical lack of resources and understanding for people living with this disabling disorder. After years of dedicated effort and collaboration, the FDA approval of Enspryng exemplifies how patients, industry, and academia can find solutions together.”[2]

Enspryng will be made available in the US in the next couple of weeks. It has been previously approved in Canada, Japan, and Switzerland while under review in the EU and China.

Clinical Trials

The FDA approval was based on results from two landmark clinical trials, namely SAkuraStar and SAkuraSky. SAkuraStar is a Phase III randomized, double-blind, the multicenter study aimed to evaluate the safety and efficacy of the drug Enspryng as a monotherapy. Around 95 patients with NMOSD were enrolled for this study, and they were treated either with Enspryng monotherapy or placebo.

The patients were treated for 1.5 years, and the primary endpoint of the study was the time to first protocol-defined relapse (PDR). 67% of the patient population was AQP4 antibody-positive patients. In the AQP4 antibody-positive subgroup, approximately 77% of the patients treated with Enspryng were relapse-free at 96 weeks, while 41.1% were relapse-free in the placebo group. The results from this trial were presented at the 35th Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS), last year, and later published in The Lancet Neurology [2].

SAkuraSky is also a Phase III randomized, double-blind study to test the efficacy and safety of Enspryng in combination with other immunosuppressant therapy. Around 76 patients with NMOSD were either treated with Enspryng or placebo added to baseline therapy (azathioprine, mycophenolate mofetil, and/or corticosteroids). The study was concluded when the number of PDR reached 26. Roughly 70% of the patient population was AQP4 positive. 91.1% of patients treated with Enspryng in the AQP4 antibody-positive subgroup patients were relapse-free at 96 weeks, compared to only 56.8% with placebo. These exciting results were published in the New England Journal of Medicine (NEJM) [2].

The most prevalent adverse events from the treatment of Enspryng include nasopharyngitis, headache, upper respiratory tract infection, gastritis, rash, and others.

Related Article: Genentech Enters Spinal Muscular Atrophy Market with Risdiplam’s FDA Approval

References

1. https://rarediseases.org/rare-diseases/neuromyelitis-optica/
2. https://www.gene.com/media/press-releases/14873/2020-08-14/fda-approves-genentechs-enspryng-for-neu

Author

Tulip Chakraborty