Audentes Therapeutics (NASDAQ:BOLD) does not plan to increase the dose for its next drug treatment cohort in its Phase I/II ASPIRO trial of gene therapy AT132 against X-linked myotubular myopathy (XLMTM) despite the company saying otherwise, said a source familiar. Rather, due in part to a potentially worrisome safety signal, the company intends to keep dosing patients at the same level as announced in recent data, the source said.
According to ClinicalTrials.gov (NCT03199469), the study has three interventional cohorts. Cohort 1 was given 1.0 x 10^14 vg/kg of AT132, cohort 2 is planned for a 3.0 x 10^14 vg/kg dose and cohort 3 will be given 5.0 x 10^14 vg/kg of AT132.
The company recently announced positive interim data from the first cohort's three patients dosed in the 12-patient trial. When the interim data was announced the stock rose by 14.8%. Audentes also stated in its most recent financial filing that based on AT132’s encouraging preliminary profile in these patients it plans to enroll an additional three patients at the same 1x1014 vg/kg dose, prior to opening a new dose cohort.
But according to conversations with the company, the source said it also currently expects to treat the next cohort at the lowest dose rather than going to the higher dose stated on ClinicalTrials.gov. Although the current data indicate promising efficacy, worrisome enzyme findings that indicate a possible immune response also influence the decision to restrict the dose potential, the source said.