A clinical trial supported by the National Institutes of Health (NIH) was stopped early after researchers found sufficient evidence that a drug used to treat bone marrow cancer and Kaposi sarcoma is safe and effective in treating hereditary hemorrhagic telangiectasia (HHT).
The trial results, which are published in the New England Journal of Medicine, detail how patients with HHT given the drug, called pomalidomide, experienced a significant reduction in the severity of nosebleeds, needed fewer of the blood transfusions and iron infusions that HHT often demands, and showed improved quality of life.
Researchers speculated that pomalidomide worked by blocking the growth of abnormal blood vessels. It may cause the blood vessels to have a more normal structure or thicker walls so they are less fragile. However, the research team, led by Keith McCrae, M.D., professor of molecular medicine at the Cleveland Clinic, says further study will be needed.
Researchers enrolled 144 adults with HHT at 11 U.S. medical centers between Nov. 5, 2019, and June 27, 2023. All participants had moderate to severe nosebleeds requiring iron infusions or blood transfusions. Researchers gave 95 of the participants 4 mg of pomalidomide daily, though the dosage was reduced to 3 mg or 2 mg daily in patients with adverse reactions — mostly constipation, rashes, and lower than average white blood cell counts. The remaining 49 patients received a daily sugar pill designed to look exactly like the pomalidomide pill, in addition to their usual care.
At the start of the trial, researchers used a validated HHT-specific bleeding assessment tool to score each patient’s nosebleed severity. To establish a baseline in other areas, participants self-reported other data throughout the trial, particularly the severity of their nosebleeds and the effect of their HHT symptoms on everyday activities using a special scoring system. The number of units of red blood cells transfused or iron infused was also recorded.
In June 2023, 43 months into the scheduled four-year trial, an interim analysis found pomalidomide had met a prespecified threshold for efficacy, and the trial was closed to further enrollment.
Though researchers did not follow participants after the trial ended, McCrae noted that some of his patients from the study have gone four to six months without a recurrence of nosebleeds, even though they had stopped the medication. This suggests that the drug may have promise as a long-term or intermittent treatment.
