Larimar's limbo finally ends as FDA removes clinical hold on only asset

Larimar Therapeutics held its breath for over a year, but the FDA has finally given the biotech a green light to continue trials of its lead, and only, asset this year.

To coincide with its announcement of the FDA's decision regarding its Friedreich’s ataxia drug CTI-1601, the biotech also unveiled a $70 million underwritten offering. Despite the freeze on its only asset, Larimar reported cash and securities of $54.9 million as of the end of June, which it estimates will last through the third quarter of 2023. 

The FDA, which previously gave the therapy a fast-track tag, halted the trial program in May 2021 after Larimar sent off data showing a number of deaths that occurred at the highest dose levels in a nonhuman primate toxicology study.

After a meeting with the agency, the biotech announced last month that it was preparing to submit a full response, including plans for a phase 2 trial of the drug at a lower dose. The company said it had proposed a four-week phase 2 trial to collect data on extending the lower dose of CTI-1601 as well as to explore whether lower doses for longer periods can safely increase frataxin levels.

The company had previously pointed to data from phase 1 single- and multiple-ascending dose clinical trials to demonstrate that daily subcutaneous injections of doses of up to 100 mg of CTI-1601 for up to 13 days were generally well tolerated.

Now, the FDA has cleared a phase 2 study of a much lower dose, 25 mg. Aside from a requirement that the agency review data before the trial is escalated to a further cohort, the study design otherwise remains the same as the version Larimar had proposed.

With the FDA satisfied, the biotech is preparing to launch the trial in the fourth quarter, with a top-line readout expected in the second half of 2023.

“Given the strength of our phase 1 data and the urgent need for a disease-modifying FA therapy, we believe today’s news is an important event for not only Larimar but for the entire FA community,” Larimar CEO Carole Ben-Maimon, M.D., said in a press release. “We are now working expeditiously to initiate our phase 2 dose exploration trial next quarter. We anticipate that the results of this trial will provide crucial safety, pharmacokinetic and pharmacodynamic data that will inform the design of future studies.”

The therapy, CTI-1601, is a recombinant fusion protein intended to deliver human frataxin into the mitochondria of Friedreich’s ataxia patients. The autosomal-recessive genetic disease causes difficulty walking, a loss of sensation in the arms and legs and impaired speech that worsens over time and usually starts in childhood.

The news from the FDA didn’t appear to give any immediate boost to Larimar’s shares, which were down 5% at $2.99 in premarket trading Sept. 14.