Larimar tumbles on FDA clinical hold for Friedreich's ataxia drug CTI-1601

Shares of Larimar Therapeutics were down as much as 40% on Wednesday after it said the FDA placed a hold on the clinical programme for its Friedreich's ataxia drug candidate CTI-1601, and that the company would not be closing a previously announced private placement financing of about $95 million. The clinical hold comes after Larimar notified the FDA of deaths that occurred at the highest dose levels in an ongoing non-human primate (NHP) toxicology study, which is designed to support extended dosing of patients with CTI-1601.

According to Larimar, the FDA wants to see a full report from the ongoing NHP study, and the company will not be able to initiate any additional clinical trials until it gets a greenlight from the agency. CTI-1601 is a recombinant fusion protein designed to deliver human frataxin into the mitochondria of patients with Friedreich's ataxia, with the aim of easing symptoms and halting or slowing disease progression by restoring frataxin to healthy levels.

Larimar recently reported data from a Phase I multiple ascending dose (MAD) trial in adults showing that, compared to placebo, daily subcutaneous injections of CTI-1601 for up to 13 days resulted in dose-dependent increases in frataxin from baseline in all evaluated tissues, including buccal cells, skin biopsies and platelets. From a safety standpoint, Larimar said repeated subcutaneous injections of CTI-1601 were generally well tolerated at doses up to 100 mg given daily for 13 days, with no treatment-related severe adverse events.

Company still sees path forward

CEO Carole Ben-Maimon said the FDA action nevertheless "does not change our previously stated clinical development strategy for CTI-1601." Larimar plans to complete the NHP toxicology study before seeking FDA consent to initiate the company's Jive and paediatric MAD trials. "Based on all of the information we have regarding CTI-1601's safety profile to date, we continue to believe there is a path forward toward the initiation of our Jive and paediatric MAD trials," Ben-Maimon stated, but given the regulatory hurdles that come with responding to a clinical hold, "there is a possibility that the initiation of these trials may be delayed into 2022."

Meanwhile, Ben-Maimon said that despite its termination of the private placement financing, Larimar still has $81.4 million in cash and investments, funding which supports "cash runway through the first half of 2022."

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