The oral splicing modifier RG7800 increases full length survival of motor neuron 2 mRNA and survival of motor neuron protein: Results from trials in healthy adults and patients with spinal muscular atrophy.

Spinal muscular atrophy (SMA) is a rare genetic and progressively debilitating neuromuscular disease. It is the leading genetic cause of death among infants. In SMA, low levels of survival of motor neuron (SMN) protein lead to motor neuron death and muscle atrophy as the SMN protein is critical to motor neuron survival. SMA is caused by mutations in, or deletion of, the SMN1 gene. A second SMN gene, SMN2, produces only low levels of functional SMN protein due to alternative splicing which excludes exon 7 from most transcripts, generating truncated, rapidly degraded SMN protein. Patients with SMA rely on limited expression of functional SMN full-length protein from the SMN2 gene, but insufficient levels are generated. RG7800 is an oral, selective SMN2 splicing modifier designed to modulate alternative splicing of SMN2 to increase the levels of functional SMN protein. In two trials, oral administration of RG7800 increased in blood full-length SMN2 mRNA expression in healthy adults and SMN protein levels in SMA patients by up to two-fold, which is expected to provide clinical benefit.

Effect of the mGluR5-NAM Basimglurant on Behavior in Adolescents and Adults with Fragile X Syndrome in a Randomized, Double-Blind, Placebo-Controlled Trial: FragXis Phase 2 Results.

Preclinical data suggest that inhibition of the metabotropic glutamate receptor 5 (mGluR5) receptor might hold therapeutic benefits in Fragile X syndrome (FXS). Treatment of Fmr1 knockout mice with mGluR5-negative allosteric modulators (NAMs) has been reported to correct a broad range of phenotypes related to FXS. The early short-term clinical trials with mGluR5 NAMs, including basimglurant, assessing the effects in individuals with FXS, were supportive of further exploration in larger, well-controlled trials. We evaluated basimglurant, a potent and selective mGluR5 NAM, in a 12-week, double-blind, parallel-group study of 183 adults and adolescents (aged 14-50, mean 23.4 years) with FXS. Individuals with an FMR1 full mutation were randomized to placebo or one of two doses of basimglurant. The primary efficacy endpoint was the change from baseline in behavioral symptoms using the Anxiety Depression and Mood Scale (ADAMS) total score. All treatment arms showed marked behavioral improvements from baseline to week 12 with less improvement in the basimglurant 1.5 mg arm than placebo; however, basimglurant 0.5 mg was inferior to placebo in the ADAMs total score. Treatment with basimglurant was overall well-tolerated. A higher incidence of adverse events classified as psychiatric disorders were reported in patients treated with basimglurant, including three patients with hallucinations or psychosis. In this phase 2 clinical trial, basimglurant did not demonstrate improvement over placebo. Evaluation of the overall risk-benefit in younger patient populations is an important consideration for the design of potential further investigations of efficacy with this class of medications.