FDA clears higher dose of CTI-1601, launch of open-label extension

In Phase 2 study, Larimar will test treatment at 50 mg

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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The U.S. Food and Drug Administration (FDA) has greenlighted a request by Larimar Therapeutics to test a 50 mg dose of CTI-1601 on people with Friedreich’s ataxia (FA) and cleared the company to begin an open-label extension study of the treatment.

“Gaining clearance to advance to a 50 mg cohort in our Phase 2 trial and initiate the OLE trial are crucial steps in CTI-1601’s development as potentially the first therapy to increase frataxin levels in patients with FA,” Carole Ben-Maimon, MD, president, and CEO of Larimar, said in a company press release. “Given the inability of current treatments to address the frataxin deficiency underlying Friedreich’s ataxia, we believe CTI-1601 has the potential to improve the treatment paradigm for this devastating disease.”

CTI-1601 is designed to deliver a functional version of frataxin, the protein whose defect causes FA, to cells. It’s administered by an injection under the skin, or subcutaneously.

Larimar is sponsoring a Phase 2 trial (NCT05579691) of CTI-1601 against a placebo in people with FA. In the study’s first part, patients were given 25 mg of the therapy or a placebo daily for two weeks then every other day for two more weeks. Top-line results from a few months ago suggested it boosted frataxin levels in cells. No serious side effects were reported.

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With the FDA’s clearance, Larimar plans to test the therapy at a 50 mg dose, administered at the same schedule — every day for two weeks and every other day for another two weeks. The study is recruiting adults at a site in New Jersey.

Larimar also will start an open-label extension study (OLE), wherein all patients will be given daily 25 mg injections of CTI-1601 and monitored for long-term outcomes. It will be open to patients who’ve completed the Phase 2 study or earlier CTI-1601 trials. Interim data are expected toward the end of next year.

“We are pleased to have clearance to begin our OLE trial and look forward to what we expect will be important interim data from the study in Q4 2024,” Ben-Maimon said.

The CTI-1601 program has been under a partial clinical hold since 2021 after the FDA cited safety concerns and asked for additional data. In accordance with the hold, further dose increases for the Phase 2 or OLE studies, or additional U.S. studies, are contingent on the results from the Phase 2 study’s 50 mg group. The results are expected in the first half of next year, according to Larimar.

“We now look forward to data from our Phase 2 trial’s 50 mg cohort in the first half of 2024, which will help us further characterize the safety and [pharmacological] profiles of CTI-1601 and its ability to increase frataxin levels in a dose-dependent fashion as seen in our earlier Phase 1 studies,” Ben-Maimon said. “Alongside our efforts to advance both our OLE and Phase 2 trials in the United States, we have also begun to engage with regulators and investigators outside the U.S. as we prepare to expand our clinical program to additional geographies.”

Ben-Maimon said it’s important to set up “global clinical trial” given that about 75% of FA cases are outside the U.S.