FDA clears 2 therapies for rare conditions

August 18, 2020
Christine Blank
Christine Blank

Drug for a specific Duchenne muscular dystrophy mutation is only the second drug approved for the mutation.

The FDA recently approved two novel treatments for rare conditions: one for a certain mutation in Duchenne muscular dystrophy (DMD) and another for neuromyelitis optica spectrum disorder (NMOSD) for those who have a specific antibody.

The agency granted accelerated approval to viltolarsen injection (Viltepso, NS Pharma) to treat DMD in patients who have a confirmed mutation of the DMD gene that is amenable to exon 53 skipping. This is the second FDA-approved targeted treatment for patients with this type of mutation, which affects around 8% of DMD patients.

Related: Top 3 drugs to watch in second half 2020

Viltepso was evaluated in two clinical studies with a total of 32 patients. In one study, dystrophin levels increased, on average, from 0.6% of normal at baseline to 5.9% of normal at week 25.

“The FDA concluded that the applicant’s data demonstrated an increase in dystrophin production that is reasonably likely to predict clinical benefit in patients with DMD who have a confirmed mutation of the dystrophin gene amenable to exon 53 skipping,” the agency said in a press release.

However, a clinical benefit of the drug has not been established, FDA said. As part of the accelerated approval process, the agency is requiring the company to conduct a clinical trial to confirm the drug’s clinical benefit.

FDA also cleared satralizumab-mwge (Enspryng, Genentech) for NMOSDin adults with a particular antibody: patients who are anti-aquaporin-4 or AQP4 antibody-positive.

Enspryng is the third approved treatment for the disorder, a rare autoimmune disease of the central nervous system that mainly affects the optic nerves and spinal cord.

Related: FDA clears novel psoriatic arthritis treatment

“Until last year, there were no FDA-approved treatments for patients with this rare, debilitating and sometimes fatal disease. Now there are three,” said Billy Dunn, MD, director of the Office of Neuroscience in the FDA’s Center for Drug Evaluation and Research, in a press release. “Today’s approval of Enspryng highlights the FDA’s commitment to rapidly advancing safe and effective therapies for NMOSD and other neurological diseases.”

The effectiveness and safety of Enspryng was demonstrated in two, 96-week clinical studies. In the first study, Enspryng reduced the number of NMOSD relapses by 74% in patients who were anti-AQP4 positive compared to treatment with a placebo (inactive treatment).

In the second study, treatment with Enspryng reduced the number of relapses in patients who were anti-AQP4 positive by 78% compared to treatment with a placebo.

The prescribing information for Enspryng includes a warning for increased risk of infection, including serious and potentially fatal infections — such as potential reactivation of hepatitis B and tuberculosis. Other warnings and precautions for Enspryng include elevated liver enzymes, decreased neutrophil counts and hypersensitivity reactions.

Read more: FDA clears first drug to treat spinal muscular atrophy