The STEADY-PD clinical trial has failed to show that isradipine is an effective treatment to slow or stop progression in early Parkinson's.
Researchers at the Northwestern Medicine have announced that their phase 3 trial of isradipine for early Parkinson's has failed.
Over the 36-month placebo-controlled study, the repurposed drug failed to significantly improve Unified Parkinson Disease Rating Scale (UPDRS) scores. This suggests that the drug is not able to significantly slow or stop clinical progression in early Parkinson's.
The research was presented at the 2019 American Academy of Neurology (AAN) Annual Meeting, in Philadelphia, Pennsylvania.
Reducing calcium levels in the brain
Isradipine is a calcium channel blocker usually prescribed for the treatment of high blood pressure, in order to reduce the risk of stroke and heart attack. It was thought that isradipine might be protective in Parkinson's because the affected dopamine-producing brain cells are continuously flooded with calcium, which is believed to contribute to damaging oxidative stress and ultimately cell death.
Following promising results in animal models and small-scale clinical trials, in 2014, researchers in the US received $23 million to conduct a phase 3 trial of isradipine in 336 people with Parkinson's.
Study author Tanya Simuni, MD said:
"Of course, this is disappointing news for everyone with Parkinson disease and their families, as well as the research community. However, negative results are important because they provide a clear answer, especially for the drug that is commercially available. We will all continue to work to find a treatment that can slow down or even cure this disease."
Dr Lynn Duffy, Senior Scientific Copy Writer at Parkinson's UK, said:
"It was disappointing to hear that the STEADY-PD trial has not been successful. Around 145,000 people are currently living with Parkinson's in the UK, and existing treatments are unable to slow progression of the condition. We desperately need to find treatments that can slow or stop Parkinson's progression, and will continue to fund and support research until this breakthrough is achieved."