Santhera presents new efficacy data with Raxone for Leber's hereditary optic neuropathy

Swiss specialty drugmaker Santhera Pharmaceuticals (SIX: SANN) says that current data from the expanded access program (EAP) demonstrate that 50% of patients have achieved a clinically relevant improvement in their vision and 63% of the patients were protected from further vision loss following Raxone (idebenone) treatment.

Raxone was safe and well tolerated following long-term use in the EAP, which provides further evidence of safety and efficacy for the drug in the treatment of Leber’s hereditary optic neuropathy (LHON) in the routine clinical setting.

Safety and efficacy data were collected in an ongoing EAP for LHON patients with recent onset of symptoms in which they were given access to Raxone in response to an unsolicited request from their treating physician. As of January 31, 2014, 29 physicians in Europe, the USA, Australia and New Zealand had enrolled 61 LHON patients. Participants received Raxone typically at 900mg/day and were assessed for safety and visual acuity (VA) during routine clinical care for up to 21 months. Currently data from 48 patients carrying the G11778A, G3460A or T14484C mutation have provided best corrected VA data from at least one on-treatment visit. Patient demographics such as distribution of mtDNA mutation carried, gender, age and extent of VA loss of enrolled patients were consistent with the known natural history of LHON. Efficacy analyses assessed (i) the proportion of patients with clinically relevant and stable improvement in VA and (ii) the proportion of patients without further deterioration in VA.

Further study findings

In the EAP, 24 of 48 patients (50%) have so far experienced a clinically relevant and stable improvement in VA defined as either (i) improvement from VA nadir of at least 10 letters (logMAR 0.2) on the ETDRS chart or (ii) improvement to reading at least 5 letters on-chart in patients with severe vision loss unable to read any letters on the ETDRS chart at nadir. In both cases, VA recovery had to be stable until the last available visit. Patients have been treated for an average of 11 months (range 3 to 21 months). Analyzed by disease-causing mtDNA mutation carried, 89% of patients with the T14484C mutation, 70% with the G3460A and 31% with the G11778A mutation have had clinically relevant recovery of vision. The percentage of Raxone® treated patients with VA recovery is markedly higher than that observed in a comparable population from a recently completed natural history case record survey of over 350 LHON cases collected from centers in Europe and the USA.

In the EAP, the average treatment effect size in patients with VA recovery was 29 letters from the VA nadir across all mtDNA mutations (49 letters for patients with the T14484C, 26 letters for patients with the G3460A and 13 letters for patients with the G11778A mtDNA mutation). The efficacy of Raxone in promoting recovery of VA occurs rapidly, as 75% of patients have responded within the first 6 months and 83% within 12 months of the initiation of Raxone treatment.