Drug Tolerance is Likely Culprit Behind the Failure of MGluR5 Clinical Trials

Drug Tolerance is Likely Culprit Behind the Failure of MGluR5 Clinical Trials

We have long suspected that the clinical trials of mGluR5 blockers from Novartis and Roche failed because the drug triggered tolerance, losing effect over time. With a $90,000 grant from FRAXA, Dr. Patrick McCamphill, a Postdoctoral Fellow in the MIT lab of Dr. Mark Bear, is investigating. He does indeed find tolerance, and now he is looking for ways to overcome it.

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Pharmacological Tolerance in the Treatment of Fragile X Syndrome

Pharmacological Tolerance in the Treatment of Fragile X Syndrome

With a $90,000 grant from FRAXA Research Foundation over 2018-2019, Dr. Patrick McCamphill, postdoctoral fellow in Dr. Mark Bear’s lab at Massachusetts Institute of Technology (MIT), is investigating drug tolerance to mGluR5 antagonists, arbaclofen, and other potential Fragile X treatments. He is also exploring ways to overcome it.

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Mechanisms of Tolerance to Chronic mGluR5 Inhibition

Mechanisms of Tolerance to Chronic mGluR5 Inhibition

Over the past few years, both Novartis and Roche sponsored large-scale clinical trials of metabotropic glutamate receptor 5 (mGlu5) negative allosteric modulators (NAMs) to treat Fragile X syndrome (FXS). With a $90,000 grant from FRAXA Research Foundation in 2015-2017, Dr. Mark Bear’s team will explore if mGlu5 NAMs dosed chronically causes tolerance, and if so, how it develops and to probe new avenues to prevent or circumvent it.

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Did Tolerance Result in Fragile X mGluR5 Clinical Trial Failures?

Did Tolerance Result in Fragile X mGluR5 Clinical Trial Failures?

Although the clinical trials failed to show efficacy in the patient population and Novartis and Roche discontinued their Fragile X development programs, Dr. Senter has worked with Mark Bear, PhD to carefully review parent observations. Those caregiver reports suggested tolerance to mGlu5 antagonists antagonists developed quickly, consistent with some preclinical findings in the mouse model.

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