The US Food and Drug Administration placed a clinical hold on Tenaya Therapeutics’ gene‑therapy study for a heart disease indication, citing the need to standardize immunosuppression regimens across trial sites. The sponsor must align trial practices and submit corrective plans before dosing can resume. Tenaya’s program involves systemic gene delivery with concomitant immunosuppression; regulators flagged variability in site‑level immunosuppression as a patient‑safety and data‑integrity concern. The hold pauses enrollment and treatment in the affected study. The action highlights regulatory scrutiny of complex gene‑therapy protocols and the operational challenge of harmonizing immunomodulatory support in multi‑site trials.