Dosing in a phase 2 clinical trial to assess the safety of RG7800 in patients with spinal muscular atrophy (SMA) has been temporarily stopped based on emerging data from preclinical animal studies. PTC Therapeutics announced that long term preclinical animal data has revealed ‘an eye finding’ that the company wants to better understand before proceeding further with the phase 2 study. The company did not elaborate further on the eye finding except to say that it was observed in some animals in which the RG7800 concentrations were higher than those being used in the human studies.
Last month at the American Academy of Neurology Annual Meeting, the company announced that phase 1 results in human volunteers given RG7800 demonstrated a significant and dose-dependent increase in the production of full length SMN2 mRNA. The Phase 1 clinical study was completed in the spring of 2014 and was well tolerated at all dose levels studied.
Dosing of the phase 2 ‘MOONFISH’ study had begun and according to PTC Therapeutics, a preliminary review of the data did show RG7800 was well tolerated and increased full length SMN2 mRNA in patients with SMA.
So far, the eye finding has not been observed in any humans give RG7800 but the company has halting dosing to evaluate these animal study findings and to determine how to proceed with the phase 2 study.
Meanwhile, PTC Therapeutics’ Translarna (ataluren) program continued to be on track. Ataluren was approved in Europe to treatment patients with nonsense mutation Duchene muscular dystrophy and as of April 30th, 82 Duchenne patients are taking the commercial therapy through either reimbursed early access programs or commercial sales.
In the United States, PTC Therapeutics began submitting a rolling New Drug Application to the FDA for the approval of Translarna in nonsense mutation DMD in December 2014 and the company is gearing up for a potential launch in 2016.
Ataluran is also being testing in patients with cystic fibrosis (phase 3 study_ and aniridia (phase 2 study).
PTC Therapeutics Reports First Quarter 2015 Financial Results and Provides Corporate Update [press release]. South Plainfield, NJ: PTC Therapeutics; May 4, 2015. http://ir.ptcbio.com/releasedetail.cfm?ReleaseID=910618