Results from major Parkinson’s clinical trials, of the blood pressure medication isradipine and the cancer treatment nilotinib, found that these drugs had no effect on the progression of the disease. Now, post-hoc analyses of the trial data have identified some interesting results that may deserve further investigation.

A post-hoc analysis involves further study of data after an investigation has ended; and trying to find patterns that were not part of the initial primary outcomes. A post-hoc study is carried out using data that has already been collected, but instead, this data forms new analyses carried out for new outcomes.

Many of the datasets generated by large clinical trials are very big and provide rich resources for such analyses; even studies that did not have positive efficacy results can offer ample opportunity for ‘deep diving’ into new analyses for new objectives.

Recently, researchers have conducted post-hoc studies of two Parkinson’s clinical trials, with some interesting results.

Researchers involved with the STEADY-PD clinical trial evaluating the disease modifying potential of the blood pressure medication isradipine in people with Parkinson’s, have re-analysed the trial data and found that a higher dosage may have some beneficial effects on Parkinson’s progression, for example a later initiation of Parkinson’s medication.

This post-hoc analysis is consistent with another such analysis of a different isradipine clinical study, which found similar results. Cure Parkinson’s Director of Research, Dr Richard Wyse, was involved in this new report.

The second report re-analysed data from a clinical trial conducted at Georgetown University which evaluated the cancer treatment nilotinib in people with Parkinson’s.

Their re-examination points towards some results suggesting positive effects, but these findings will require further investigation. A parallel clinical trial of nilotinib (supported by Cure Parkinson’s and Van Andel Institute) did not find the same results and indicated that the drug was insufficiently accessing the brain.

It is important to understand that these studies involve re-analysing data in a biased fashion – searching results for any interesting correlations or effects, and as such, these investigations should be considered as ‘hypothesis generating’ exercises. Researchers use these sorts of analyses to find new ideas for experiments that can then be tested, and further research will be required before isradipine or nilotinib can be re-examined in people with Parkinson’s.

Dr Simon Stott, Deputy Director of Research, Cure Parkinson’s

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