FDA Greenlights Zevra's Rare Disease Drug After Resubmission

The FDA has granted approval to Zevra Therapeutics for the treatment of Niemann-Pick disease type C, a rare genetic disorder characterized by the accumulation of certain fatty substances in the body. This progressive condition often leads to severe neurological complications. The newly approved medication, Arimoclomol, will be marketed under the name Miplyffa and is intended for patients aged two years and older who exhibit neurological symptoms of the disease. The treatment involves taking the pill three times daily.

Despite the approval, Zevra has yet to disclose the pricing for Miplyffa. The company plans to hold a conference call on Monday but has not clarified whether it has received a priority review voucher from the FDA, although it is eligible for one. Zevra’s stock, traded under the ticker ZVRA, experienced a temporary trading halt shortly after the market opened on Friday.

Niemann-Pick disease falls under a broader category of lysosomal storage disorders, where essential enzymes for recycling substances in the body malfunction, leading to the buildup of toxic substances. This accumulation can cause damage to various organs. Analyst Lachlan Hanbury-Brown from William Blair estimates that there are approximately 300 to 350 patients with this condition in the United States.

The FDA's decision came after a closely watched advisory committee meeting in August, where experts voted 11-5 in favor of the drug. Those who supported the approval cited clinical trial data and patient testimonies suggesting that the drug may help stabilize the disease and, in some cases, improve symptoms, despite not being dramatically effective.

Initially, the FDA had rejected Arimoclomol in 2021. Following this, Zevra conducted a reanalysis of the key clinical trial data, employing a revised scale for the primary endpoint. This new scale concentrated on measures of swallowing, a skill that deteriorates as the disease progresses, and excluded cognitive measures that had previously raised concerns about data reliability.

Patients participating in the clinical trials received Arimoclomol alongside standard care. Notably, 78% of these patients also used Zavesca off-label. Zavesca, marketed by Johnson & Johnson for some Gaucher disease patients in the U.S., is approved for Niemann-Pick in the EU, Canada, and Japan, but not in the U.S., where it was rejected by the FDA in 2010.

One of the significant challenges discussed by the advisory committee was distinguishing the effects of Miplyffa from those of Zavesca. However, FDA officials indicated that Arimoclomol would likely be administered in addition to standard care, which often includes off-label use of Zavesca.

Originally developed by the Danish biotech company Orphazyme, Arimoclomol became part of Zevra’s portfolio after it acquired Orphazyme and the drug for $12.8 million in 2022. Orphazyme gained notoriety as a "meme stock" with high valuations before the FDA's rejection of the drug. Zevra, formerly known as KemPharm, rebranded itself in early 2023.

This FDA approval marks a significant milestone for Zevra and offers a new therapeutic option for patients battling Niemann-Pick disease type C. As the company moves forward, it will be crucial to monitor how Miplyffa is integrated into existing treatment regimens and its impact on patient outcomes.