Interim data from Tenaya’s MyClimb natural history study of MYBPC3-associated pediatric HCM reported a 93% prevalence of nonobstructive disease among 213 participants, with transparent genotype-based risk gradients and a potential surrogate marker emerging. Nearly all infants with biallelic truncating variants died or required a transplant before age one. Compound heterozygous children, diagnosed at a median of 2.9 years, saw 63% heart failure–related hospitalizations and 27% transplant or death. Heterozygous children, diagnosed at a median of 6.5 years, had 27% heart failure–related hospitalizations and 13% arrhythmia symptoms. Initial modeling linked every 10 g/m2 increase in left ventricular mass index (LVMI) to a 10% rise in hazard for serious events in compound heterozygous and heterozygous cohorts.
The core news is an ESC 2025 presentation of interim results from the most extensive known noninterventional study in this setting, enrolling participants diagnosed before 18 and pulling from 27 centers across the U.S., Canada, Spain, and the UK. The dataset includes 173 retrospective and 42 prospective records. While descriptive by design, the readout does more than catalog risk; it isolates genotypic status as a major predictor and positions LVMI as a candidate surrogate endpoint in a population where 93% are nonobstructive and lack approved therapies.
Strategically, this is a foundational move to de-risk pediatric gene therapy development for Tenaya’s AAV9 program TN-201. The company is building a genotype-anchored natural history that can support external controls, refine inclusion criteria to high-risk subgroups, and justify an imaging-based surrogate to accelerate pivotal evaluation. The emphasis on nonobstructive disease is notable, as there are no approved pediatric options and limited adult readthrough. Tenaya is signaling a path that leans on biomarker-driven efficacy rather than hard outcomes that are slow to accrue and operationally challenging in rare pediatric cardiomyopathies.
For sites and CROs, the implications are concrete. Enrollment will hinge on rapid, standardized genetic testing and counseling workflows, as well as consistent LVMI measurement across echo and MRI, likely under a central imaging lab. The risk stratification framework points to tighter surveillance for arrhythmias and heart failure events, and to eligibility screens that privilege compound heterozygous and high-LVMI heterozygous patients. Regulators have encouraged stronger natural history controls in rare pediatric gene therapy; this dataset addresses that expectation and could underpin single-arm designs with external comparators. Vendors with strengths in imaging standardization, pediatric cardiac monitoring, and longitudinal data capture will be in demand. For patients and their families, the findings support earlier diagnosis and proactive monitoring, while setting the stage for intervention closer to disease onset.
The next inflection will be whether FDA and EMA accept LVMI as a reasonably likely surrogate for accelerated pathways and how narrowly Tenaya defines “high risk” for pediatric entry criteria. Upcoming TN-201 updates later this year will need to demonstrate dose, safety, and biomarker durability that can be credibly translated to children, alongside a clear immunosuppression strategy given AAV redosing constraints. Watch for expansion of the prospective MyClimb cohort, alignment with regulators on external control methodology, and evidence that imaging variability is controlled to a degree that makes LVMI fit for purpose in a pivotal. Manufacturing readiness and global site activation timelines will determine how quickly any pediatric pivot can move once alignment on endpoints is secured.
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.
