PTC Therapeutics Provide Preliminary Clinical Data on RG7916
11 July 2017
PTC Therapeutics presented an update on their splice-modifying drug, RG7916, at the 2017 Cure SMA Conference in Orlando, USA.
RG7916 is a small molecule, oral drug that targets and encourages the SMN2 backup gene to produce more functional SMN protein, which is lacking in people with SMA. The FDA recently granted Orphan Drug Status to RG7916 (click here for more information).
Early data from a Phase II trial, known as SUNFISH, indicate that SMA Type 2 and 3 patients treated with RG7916 showed a robust increase (approximately four-fold) in the availability of full length SMN messenger RNA (mRNA) made from the SMN2 gene (click here for more information on mRNA and this process).
Although SMN protein levels were not reported on, this rise in the amount of full length SMN RNA will likely result in increased levels of the SMN protein made by SMN2. However, it should be kept in mind that SMN mRNA levels were measured in patient blood samples, and therefore do not necessarily reflect exactly what is happening in the motor neurons of these patients.
In addition, no adverse drug-related events causing withdrawal from the trial have yet been observed, indicating that RG7916 is likely safe and generally well tolerated by the SMA patients.
SUNFISH is a two part Phase II trial being conducted with children, young people, and adults aged 2-25 years old who have SMA Type 2 or 3. The first part of the trial is designed to evaluate the safety, pharmacokinetics, and pharmacodynamics of the drug in patients, and to select a dose for the second part of the study. The second half of the study will be used to assess both safety and efficacy of RG7916.
Both parts of the trial are randomised, placebo-controlled, and double blind, meaning that patients will be randomly allocated to either a placebo or RG7916 treatment group, and that this will be concealed from the patients and people administering the treatments.
SUNFISH is one of three ongoing clinical trials of RG7916 (click here for further information on these trials).
Results should soon be posted from a 2016 Phase 1 trial of RG7916, designed to assess its safety in healthy volunteers (click here for more information).