The company signed an agreement with the US Food and Drug Administration (FDA) regarding the trial’s design.
The phase 3 HOPE (Hemoglobin Oxygen Affinity Modulation to Inhibit HbS PolymErization) study will be carried out at leading SCD sites globally.
It will enroll up to 400 patients age 12 and older with SCD who have had at least one episode of vaso-occlusive crisis (VOC) in the earlier year.
It is a randomized, double-blind, placebo-controlled trial that will be undertaken in two parts.
The first part is dose-ranging with 900 mg and 1,500 gm of GBT440 versus placebo. It will include up to 150 patients.
The second part will include 250 patients who will be randomized to placebo or a dose of GBT440 that’s based on the first part.
The HOPE study’s endpoint will be the proportion of patients who achieve a >1 g/dL increase in hemoglobin at 24 weeks of treatment versus baseline.
GBT said the FDA is looking for the HOPE trial to meet the primary and at least one key secondary endpoint.
GBT president and CEO Ted Love said: “Solidification of the path forward for our pivotal study is an important milestone and we believe the HOPE Study design has a strong grounding in GBT440’s mechanism of action, including its potential to fundamentally modify the course of the disease by inhibiting sickle hemoglobin polymerization.”
GBT440 increases hemoglobin's affinity for oxygen. Since oxygenated sickle hemoglobin does not polymerize, the company believes GBT440 blocks polymerization and the resultant sickling of red blood cells.
It also believed that GBT440 could be capable of changing the SCD progression with the potential to restore normal hemoglobin function and enhance oxygen delivery.