FDA Keeps Hold on CTI-1601 Clinical Testing, Awaits More Data

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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The U.S. Food and Drug Administration (FDA) will maintain a hold on the clinical development of CTI-1601, Larimar Therapeutics’ experimental treatment for Friedreich’s ataxia (FA), which was originally paused for safety concerns and a request for more data.

Larimar is now analyzing data from previous studies — which include the deaths of primates treated at high dose — and deciding if more are needed to establish CTI-1601’s safety and meet the FDA’s request.

“Patient safety is our top priority,” Carole Ben-Maimon, MD, president and CEO of Larimar, said in a press release.

“Our next step is to engage with the agency to determine how we can meet their request in the most efficient and expeditious manner. Based on all available clinical and non-clinical data, we continue to believe there is a path forward through the resolution of the CTI-1601 clinical hold,” Ben-Maimon added.

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The CTI-1601 clinical program was put on hold in May 2021 after Larimar notified the FDA of the deaths of nonhuman primates, biologically similar to people, that were given a high dose of CTI-1601 in a 26-week toxicology study designed to support extended dosing in patients.

The FDA stated it would need full data from the primate study before it would allow further testing of CTI-1601 in humans, which Larimer has since submitted.

The FDA is now indicating even more data is needed before the clinical program can be resumed.

Larimar is reassessing the timing of planned clinical trials, including an open-label extension trial called Jive and a pediatric multiple-ascending dose trial. The company will operate its CTI-1601 program on a budget while it works to meet the FDA’s request.

“We remain committed to CTI-1601’s further development and are working towards this goal with a strong cash position which provides runway at least into 2023. We intend to operate under a cost reduction plan while resolving the clinical hold to manage burn and extend our cash runway if needed,” Ben-Maimon said.

FA patients lack sufficient levels of the protein frataxin. CTI-1601 is a modified version of frataxin designed to replenish its levels and ease FA symptoms.

Previous data from a Phase 1 trial (NCT04519567) showed that doses of CTI-1601 up to 100 mg a day for 13 days were well tolerated with no serious side effects reported. Patients given 50 or 100 mg doses had significantly increased frataxin levels in several tissues compared with a placebo group.

“We have a robust Phase 1 dataset, which demonstrates proof-of-concept for CTI-1601 as a frataxin replacement therapy,” Ben-Maimon said. “We believe [CTI-1601’s mechanism of action makes it] uniquely positioned to address the urgent need for disease modifying therapies in Friedreich’s ataxia, as it is designed to address the root cause of this devastating disease.” 

The FDA previously granted the therapy orphan drug and rare pediatric disease designations, in addition to placing CTI-1601 on a fast track to support its development.