Five of six evaluable patients in Tenaya’s MyPEAK-1 trial are now NYHA Class I — meaning they report no heart failure symptoms interfering with daily life — after a single infusion of TN-201 gene therapy, a result that cuts against the conventional assumption that structural cardiac disease in MYBPC3-associated HCM is largely irreversible once established. The interim data from the Phase 1b/2 study now cover 78–104 weeks for the three Cohort 1 patients and 26–52 weeks for the four patients in Cohort 2, with reductions in left ventricular mass index sustained across both cohorts and no new TN-201-associated safety events since the prior readout.
The structural signal is the centerpiece here. All six evaluable patients showed reductions in LVMI, and five of six showed reductions in one or more measures of wall thickness — the literal anatomical hallmark of the disease. Serial cardiac biopsies confirmed that TN-201 DNA transduction and mRNA expression were robust, with MyBP-C protein levels rising by an average of 4% across the cohort. That number sounds modest, but in a haploinsufficiency model where the disease state is defined by a protein deficit, restoring partial expression and watching the myocardium remodel over months is a mechanistically coherent result. Cohort 2 patients at the 6E13 vg/kg dose are reaching similar or greater clinical benefit faster than Cohort 1 did, with a mean KCCQ Clinical Summary Score improvement of 36 points — well above the 5-point threshold for clinical importance — and two of three patients posting 6-minute walk test gains of 50–255 meters against a 30-meter meaningful-change benchmark.
The regulatory backdrop adds real weight. TN-201 has now received EMA PRIME designation, a pathway reserved for therapies with preliminary evidence of substantial improvement over existing approaches in serious conditions. Separately, a pediatric indication has been accepted into the FDA’s Rare Disease Evidence Principles process, designed to offer greater predictability for very small patient populations. MYBPC3 variants account for roughly 20% of the HCM population, translating to an estimated 120,000 patients in the United States alone — a population large enough to support a meaningful commercial program if efficacy holds in a larger cohort.
The trial remains small and open-label, and the durability data beyond two years does not yet exist. But the dose-response pattern emerging between Cohort 1 and Cohort 2 is the specific signal that will define TN-201’s development trajectory: if the 6E13 vg/kg dose consistently delivers faster and deeper reductions in LVMI than the lower dose without a corresponding safety penalty, Tenaya’s path to a registrational design becomes substantially clearer. Watch the Cohort 2 one-year CPET data when it completes — peak VO2 response will determine whether the functional gains visible on echocardiogram and KCCQ translate to objective cardiopulmonary improvement at the higher dose.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
