Gene Therapy for Cerebral Adrenoleukodystrophy Earns FDA Accelerated Approval

According to a press release, the gene therapy company bluebird bio, inc. has recently announced that its gene therapy elivaldogene autotemcel (marketed as SKYSONA) has received Accelerated Approval status from the US Food and Drug Administration (FDA). This therapy is for the treatment of cerebral adrenoleukodystrophy (CALD) in boys age 4-17. This follows the lifting of a clinical hold on the therapy development program.

About Adrenoleukodystrophy (ALD)

Adrenoleukodystrophy is a genetic disease which is linked to the X chromosome. It is most characterized by the accumulation of fatty acids because the enzymes that process them are not functioning normally. This leads to damage of the myelin sheath, an insulating, fatty layer that coats nerve cells and is essential to their function. Adrenoleukodystrophy is caused by mutations that affect the ABCD1 gene. The presentation of this disease varies significantly. This makes the process of diagnosis very difficult in many cases. Some patients have no symptoms, but when they do appear, they often include neurodegeneration, paraparesis, neuropathy, behavioral abnormalities, adrenal insufficiency, and dementia. Symptoms often progress in severity without treatment. Treatment of adrenoleukodystrophy may include gene therapy, stem cell transplant, and changes in diet. These treatments are often only effective in the early stages of the disease. To learn more about adrenoleukodystrophy, click here.

Trial Findings

The Accelerated Approval follows data from a phase 2/3 clinical trial of patients with early, active cerebral adrenoleukodystrophy. These patients had limited alterations to their neurological functioning and were monitored for the appearance of six Major Functional Disabilities (MFDs), including tube feeding requirement, wheelchair dependence, loss of communication, incontinence, cortical blindness, and total loss of voluntary movements. The study found that patients treated with SKYSONA had a 72 percent chance of MFD-free survival at two years, compared to 43 percent chance in the placebo group. These findings suggest that the therapy can slow disease progression. A follow up study will monitor the patients that choose to enroll over 15 years.

About Accelerated Approval

Accelerated Approval is a protocol that can allow for more rapid access to experimental drugs that treat life-threatening diseases. This approval is based on data from “surrogate endpoints” which are believed to predict clinical benefit. This protocol requires companies to continue confirmatory studies of the therapy in question in order to prove clinical benefit as predicted by the surrogate endpoints. The drug is then granted traditional approval if the benefit is proven; otherwise, it is taken off the market.

SKYSONA will carry a boxed warning for hematological malignancy (blood cancer).   


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