2 GBT Therapies Win FDA Orphan Drug, Rare Pediatric Designations

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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orphan drug designation | Sickle Cell Disease News | announcement illustration of the word news

The U.S. Food and Drug Administration (FDA) has granted both orphan drug and rare pediatric disease designations to inclacumab and GBT601, two experimental therapies for sickle cell disease (SCD) being developed by Global Blood Therapeutics (GBT).

These designations confer benefits to therapy developers that are designed to speed the review and potential approval of treatments for rare diseases — orphan drugs — and such disorders that affect children.

“We believe that both inclacumab and GBT601 have the potential to be best-in-class therapeutic options for the treatment of this [devastating] disease,” Kim Smith-Whitley, MD, executive vice president and head of research and development at GBT, said in a press release.

“We are excited to continue these clinical development programs to make progress on our goal of transforming sickle cell disease into a well-managed condition via multiple therapeutic approaches,” Smith-Whitley said.

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voxelotor sickle cell | Sickle Cell Anemia News | trial data on Oxbryta and GBT601 | illustration of cllinical trial findings

Phase 1 Trial Supporting GBT601 as Next-gen Therapy to Oxbryta

Orphan drug designation is given to investigational therapies designed to treat diseases that affect fewer than 200,000 people in the U.S. Such status provides benefits that notably include a seven-year period of market exclusivity in the U.S. upon treatment approval.

Rare pediatric disease designation, meanwhile, is given to treatment for rare disorders that mainly affect children. Recipients of this designation qualify for a priority review voucher if the therapy is ultimately approved, in addition to meeting other conditions. The voucher may be used to request priority review of a future application to the FDA, or it may be transferred or sold.

“The FDA’s orphan drug and rare pediatric disease designations for both inclacumab and GBT601 are an acknowledgment of the critical and ongoing unmet need in sickle cell disease and the potential of GBT’s innovative pipeline of investigational medicines,” Smith-Whitley said.

Data from Phase 1 trials announced late last year by GBT showed that both inclacumab and GBT601 were well-tolerated in healthy volunteers.

Inclacumab is an antibody designed to block P-selectin, a protein that increases the stickiness of sickled red blood cells and helps them clump together. GBT is developing the into-the-vein (intravenous) therapy to reduce the risk of vaso-occlusive crises (VOCs) — painful SCD-related attacks resulting from such blood vessel blockage.

The company is running two Phase 3 trials to further test inclacumab. One study, GBT2104-131 (NCT04935879), is testing whether treatment with inclacumab every 12 weeks can reduce the risk of VOCs. The other, GBT2104-132 (NCT04927247), is assessing whether a single dose of the medication can reduce the risk of future hospitalization re-admissions due to VOCs.

The first is enrolling an estimated 240 patients, ages 12 and older, while the second is seeking 280 participants, also 12 and older. Both are actively recruiting at sites in the U.S. and Lebanon.

GBT601, also called GBT021601, is designed to increase hemoglobin’s ability to bind to oxygen, thereby reducing the sickling of red blood cells that characterizes SCD. It is designed to work in the same way as GBT’s Oxbryta (voxelotor), which was approved by the FDA for SCD in 2019.

The therapy from GBT has shown higher potency at lower doses in early studies relative to Oxbryta.

A Phase 1 study (NCT04983264) is testing single or multiple doses of GBT601, up to 100 mg/day, in six adults with SCD. Prompted by participants expressing interest in taking higher doses, GBT recently restarted the trial to test a higher 150 mg/day dosage. The company expects to present findings from this additional study later this year.