Fulcrum Therapeutics thinks it has “proof of biology” for an early-stage sickle cell disease treatment, a result that has offered a bit of optimism several weeks after the biotech announced the failure of a fast-tracked, midstage muscle degeneration drug.
It’s early days for Fulcrum’s FTX-6058, which is being developed as a potential treatment for inherited hemoglobin diseases such as sickle cell disease and beta thalassemia. But the small biotech likes what it sees in interim results from the phase 1 dosing trial of healthy patients and will begin enrollment in patients who have sickle cell disease later this year.
In the phase 1 trial, patients received either a single dose of the drug or multiple doses over 14 days. The therapy increased levels of fetal hemoglobin, which is believed to lessen the severity of sickle cell disease, according to the interim results posted Wednesday. Fulcrum also found that all dose levels in the multiple dose treatment arm achieved maximal target engagement, meaning the drug appears to be delivering the medicine as intended.
Early safety data show FTX-6058 was generally well tolerated in all groups of the study. No serious adverse events or discontinuations were reported, and any reported side effects were mild in both the single- and multi-dose groups.
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The company intends to present additional results from the trial at future medical meetings in the fourth quarter.
Fulcum will now move forward with clinical development for FTX-6058 by initiating enrollment in a phase 1b trial in patients with sickle cell in the fourth quarter. The company has chosen the multi-dose to move into the next phase, which will be administered in a three-month treatment period. This trial will help inform a later phase 2/3 trial.
But there’s more: Fulcrum said the results support a clinical trial in beta thalassemia, too. The company will seek permission with the FDA to get started by the end of the year.
The cascading clinical milestones demonstrated with FTX-6058 are good news for Fulcrum, which suffered a setback in June with the facioscapulohumeral muscular dystrophy drug losmapimod. The therapy, which was picked up from GlaxoSmithKline in 2019 for up to $37.5 million, failed to meet the goals of a phase 2b trial.
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Nevertheless, Fulcrum was “thrilled” with the data and pledged to keep pushing. The company plans to examine other clinical benefits that seemed to result from treatment with the therapy.
The FTX-6058 news drove Fulcrum’s shares up just over 200% since the news dropped Tuesday, trading at $23.44 as the markets opened Wednesday. This is compared to when the losmapimod data dropped in June and the stock stayed steady around the $8 to $9 range.