The FDA placed a clinical hold on Tenaya Therapeutics’ heart disease gene therapy trial, requesting the company standardize immunosuppression procedures across participating sites. Tenaya must align site‑level practices to address agency concerns before patient dosing can resume. The hold underscores regulator focus on consistent peri‑trial management in in vivo gene therapy studies and may delay Tenaya’s development timelines. Sponsors running immunosuppressed gene‑therapy protocols should expect increased scrutiny on regimen harmonization, monitoring and reporting as agencies weigh safety across multicenter programs.