FTX-6058 Trial Expected to Enroll Participants Through 2023

Phase 1b study of investigational oral med is open to adults ages 18–65

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

Share this article:

Share article via email
A computer screen reads

A Phase 1b clinical trial testing the safety and pharmacological properties of the investigational oral medication FTX-6058 in people with sickle cell disease (SCD) is expected to continue enrolling patients through 2023, according to Fulcrum Therapeutics, the therapy’s developer.

“We believe we are well positioned, with a strong cash runway to deliver on our upcoming catalysts as we prepare to have two registration-enabling trials in the next 18 months,” Bryan Stuart, president and CEO of Fulcrum, said in a press release.

The Phase 1b study (NCT05169580) is open to adults ages 18 to 65 who have SCD. All participants must agree to use effective contraception while in the study and for several months after its end. The trial is open to participants who are both on and off the fetal hemoglobin-boosting therapy hydroxyurea. Recruitment is underway at several sites across the U.S. More information is available here.

Recommended Reading
Blood vessels that flow through the brain carry needed oxygen to different brain regions.

Stem Cell Transplant Improves Brain Blood Flow in Children With SCD

Patients are currently being enrolled in the first two dose groups, where they will be given FTX-6058 at doses of 2 or 6 mg/day. Fulcrum also announced that the third group will be given a dose of 12 mg/day. After completing an initial treatment course of four weeks, participants will have the option of continuing treatment into an extension portion of the study for an additional period of eight weeks.

The main goal of the trial is to assess the safety profile of FTX-6058 after up to 15 weeks of monitoring. Pharmacological measures also will be assessed to determine how the therapy moves in, through, and out the body, and biological markers will be checked to see if it appears to be working as expected.

SCD is caused by mutations that disrupt the function of hemoglobin — the protein that is used to carry oxygen through the bloodstream. Abnormal hemoglobin molecules tend to form clumps in red blood cells, deforming them into the characteristic sickle shape that gives the disease its name.

Boosting HbF in red blood cells

There are two forms of hemoglobin: fetal hemoglobin (HbF), which is produced in early development and then stops being made shortly after birth, and the ault form that is defective in SCD patients. FTX-6058 is designed to boost the production of HbF in the body’s red blood cells, thereby improving oxygen transport and easing disease symptoms.

Early data from a previous Phase 1 trial (NCT04586985) in healthy volunteers indicated that FTX-6058 was able to increase HbF production.

“Now that we have established proof of concept for FTX-6058 as an oral HbF inducer … the team is focused on progressing our clinical programs and developing high-quality, compelling data,” Stuart said.