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# FDA Clinical Hold on Larimar CTI-1601
- URL: https://www.fdaweb.com/fda-clinical-hold-on-larimar-cti-1601/
- Published: 2021-05-26T12:00:00.000Z
- Updated: 2026-09-14T17:00:35.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5149408

FDA has placed a clinical hold on the Larimar Therapeutics clinical program for its CTI-1601, a recombinant fusion protein intended to deliver human frataxin into the mitochondria of patients with Friedreich’s ataxia who are unable to produce enough of the protein. The company [says](https://investors.larimartx.com/news-releases/news-release-details/larimar-therapeutics-reports-fda-clinical-hold-cti-1601-and?ref=fdaweb.com) the hold follows its notifying FDA of mortalities occurring at the highest dose levels in an ongoing 180-day non-human primate toxicology study intended to support extended dosing of patients with CTI-1601.

The agency reportedly told Larimar it needs a full study report from the ongoing primate study and said the company may not initiate additional clinical trials until it has submitted the report and been notified by FDA that additional trials can begin.

FDA has granted CTI-1601 rare pediatric disease, fast track, and orphan drug designations.