Global Blood Therapeutics (GBT), a clinical-stage biopharma focused on developing novel therapeutics for blood-based disorders, is discontinuing its GBT440 program for the treatment of idiopathic pulmonary fibrosis (IPF).
The decision came after GBT evaluated the results from three studies, including one Phase 1 study and two Phase 2a trials – the Phase 1 Basecamp study (NCT03051711), and the Phase 2a trials GBT440-006 (NCT02846324) and ZEPHYR (NCT02989168).
“From the outset, we set a high bar for success in our IPF program. The results re-affirm our confidence in the mechanism of action of GBT440,” Dr. Ted W. Love, MD, president and CEO of GBT, said in a press release.
“However, the data from these proof-of-concept studies did not demonstrate sufficient overall clinical benefit to justify continuing the program,” Love said.
“While we are disappointed that we didn’t meet our high bar for success, and we are disappointed that we will not be able to help the IPF community, we are grateful to the patients, healthy volunteers and healthcare professionals who participated in the trials and supported us in these efforts,” he added.
But GBT is advancing GBT440 for sickle cell disease, and is moving forward with clinical studies for that condition.
The investigational drug was found to be generally safe as it was well-tolerated in all three IPF studies, with no new safety issues raised. It functions by increasing the affinity, or attraction, of hemoglobin for oxygen, which benefits patients with IPF because their lungs cannot supply adequate oxygen to the blood.
In the Basecamp study, healthy volunteers received 900 mg of GBT440 under conditions of low oxygen to mimic the disease state of IPF patients. The results showed a statistically significant increase in oxygen saturation or oxygen levels in the blood, indicating that GBT440 is effective at modifying hemoglobin.
The Phase 2a GBT440-006 trial enrolled IPF patients with low oxygen levels. Those treated with 1,500 mg of GBT440 showed a statistically significant but somewhat modest dose-dependent improvement in oxygen-saturation. Unfortunately, upon evaluating the primary endpoints – such as oxygen dependency with exercise – this statistically significant increase did not lead to clinically meaningful benefits.
In the Phase 2a ZEPHYR clinical trial, patients with severe IPF who received 900 mg of the drug failed to show any improvement in oxygen saturation.
While these studies supported the drug’s proof-of-concept because they improved oxygen saturation, there is likely no clinically meaningful benefit to IPF patients.
GBT will not be investing in any additional IPF clinical trials with GBT440 and will not enroll any more patients in these trials. The company will present the complete results from each trial at a future meeting.
“We are encouraged that the safety and mechanistic data reinforce the potential of GBT440 as a disease-modifying treatment for individuals living with sickle cell disease,” Love said. “We remain on track to announce top-line clinical trial results from our Phase 3 HOPE study in the first half of 2019.”