Results of the first-ever clinical drug trial for children with Progeria, a rare, fatal "rapid-aging" disease, demonstrate the efficacy of a farnesyltransferase inhibitor (FTI), a drug originally developed to treat cancer. The clinical trial results, completed only six years after scientists identified the cause of Progeria, included significant improvements in weight gain, bone structure and, most importantly, the cardiovascular system, according to The Progeria Research Foundation (PRF) and Boston Children's Hospital. The study results were published today in Proceedings of the National Academy of Sciences (Epub ahead of print).
Progeria, also known as Hutchinson-Gilford Progeria Syndrome (HGPS), is a rare, fatal genetic disease characterized by an appearance of accelerated aging in children. All children with Progeria die of the same heart disease that affects millions of normal aging adults (atherosclerosis), but instead of occurring at 60 or 70 years of age, these children may suffer heart attacks and strokes as early as age 5, with the average age of death at 13 years.
"To discover that some aspects of damage to the blood vessels in Progeria can not only be slowed by the FTI called lonafarnib, but even partially reversed within just 2.5 years of treatment is a tremendous breakthrough, because cardiovascular disease is the ultimate cause of death in children with Progeria," said Leslie Gordon, M.D., Ph.D., lead author of the study, medical director for PRF, and mother of a child with Progeria. In addition, Dr. Gordon is a staff scientist at Boston Children's Hospital and Harvard Medical School, and associate professor at Hasbro Children's Hospital and Alpert Medical School of Brown University.
Results Yield Improvements in One or More Study Measures for All ChildrenTwenty-eight children from sixteen countries participated in the two-and-a-half year drug trial, representing 75 percent of known Progeria cases worldwide at the time the trial began. Of those, 26 are children with the classic form of Progeria. The children traveled to Boston every four months to receive comprehensive medical testing through Boston Children's Hospital's Clinical and Translational Study Unit.
Treatment consisted of the FTI lonafarnib, supplied by Merck & Co., given to children orally, twice-a-day over the course of the study, under the supervision of principal investigator Mark Kieran, M.D., Ph.D., director of pediatric medical neuro-oncology at the Dana-Farber/Children's Hospital Cancer Center.
The research team, which included specialists at Boston Children's Hospital, Brigham & Women's Hospital and Dana-Farber Cancer Institute, evaluated the children's rate of weight gain compared to their pre-therapy rate as the primary outcome because children with Progeria experience severe failure to thrive, and have a consistent, very slow linear rate of weight gain over time. Researchers also examined arterial stiffness (a predictor of heart attack and stroke in the general population), bone density and rigidity (indicators of osteoporosis). Every child completing the study showed improvement in an ability to gain additional weight, increased flexibility of blood vessels or improved bone structure.
Results included improvement in one or more of the following areas:
- Weight: One in three children demonstrated a greater than 50 percent increase in annual rate of weight gain or switched from weight loss to weight gain, due to increased muscle and bone mass.
- Bone Structure: On average, skeletal rigidity (which was highly abnormal at trial initiation) improved to normal levels after FTI treatment.
- Cardiovascular: Arterial stiffness, strongly associated with atherosclerosis in the general aging population, decreased by 35 percent. Vessel wall density also improved with treatment.
Following the 2003 discovery of the gene that causes Progeria, researchers identified FTIs as a potential drug treatment for Progeria. Children with Progeria have a genetic mutation that leads to the production of the protein progerin, which is responsible for Progeria. Progerin blocks normal cell function and part of its toxic effect on the body is caused by a molecule called a "farnesyl group," which attaches to the progerin protein. FTIs act by blocking the attachment of the farnesyl group onto progerin.
"In the early stages of planning for this clinical trial, we realized that my team's experience using FTIs to treat children with brain cancer could bring together PRF's preclinical research efforts and the expertise we needed to study the drug in children with Progeria," said Kieran, the study's senior author and associate professor of Pediatrics at Harvard Medical School. "The premise behind studying this drug was that by stopping the attachment of the farnesyl group onto progerin in children with Progeria, progerin may be inactivated, reducing some effects of the disease."