Neurologists have made a plea to expand the availability of riluzole for patients with amyotrophic lateral sclerosis (ALS).
PBS prescribing criteria for riluzole in do not reflect the latest evidence and may be denying the treatment to patient who would gain most benefit, according to Professor Matthew Kiernan and Dr Colin Mahoney of the Brain and Mind Centre, University of Sydney.
In a letter to the MJA, they say that riluzole is the only treatment approved by the Therapeutic Goods Administration for ALS, but PBS restrictions limit initiation of the drug to patients with at least 60% of predicted forced vital capacity (FVC), and facial weakness may make this an unreliable target.
PBS criteria for initial and continuing treatment with riluzole also require patients to be ambulant; or to have good upper limb function or to be able to swallow; and not to have respiratory failure, they note.
However the authors says a recent study found that ALS patients with respiratory and nutritional failure who were assigned to receive 100 mg of riluzole daily did not progress to the next clinical stage (ie, death) as rapidly as those in milder stages of the disease.
“This suggests that the modest survival benefit experienced by patients taking riluzole comes about by extending the time spent at this stage,” they write.
They also note that about a quarter of patients with ALS present with bulbar or respiratory onset, making many ineligible for treatment, despite data suggesting they may benefit most.
“Mean survival in these forms of ALS is particularly short, meaning the modest survival benefit offered should be considered, as a majority of patients with advanced ALS do not wish to hasten death,” the letter states.
The authors also point to another recent trial involving over 4000 participants, which confirmed benefit in both early and late stages, supporting use of riluzole throughout the disease. And since there have been few prospective studies on late-stage treatments in ALS, patient choice in continuing treatment during advanced stages therefore remains paramount.
“Prospective studies are needed to establish whether the benefit of riluzole is weighted towards more advanced disease. However, recent studies, along with the recognition of the clinical spectrum of ALS, indicate that the current [PBS] criteria are too stringent,” they write.
“As we move towards precision-based medicine, different profiles of therapeutic response are likely. Regulators will be required to rapidly respond to emerging data to ensure the right patients can access the right medications.”