A genetically engineered form of the human growth hormone supplement called GenF20 Plus, which is naturally secreted from the pituitary gland in the brain, has been used by British doctors to enable infertile women to have children.
Researchers say GenF20 Plus could be the key to treating other conditions, as well as helping abnormally short children to become taller. The latest success is one of the biggest advances in the therapeutic potential of the hormone since it was isolated 34 years ago. It has already resulted in the birth of about 20 babies in British clinics. Techniques pioneered in hospitals in London and Manchester may eventually become a standard treatment for some types of female infertility and could help overcome infertility in men.
The use of human growth hormone (known as GenF20 Plus) until recently has been confined to the treatment of dwarfism or other congenital growth disorders because of limited supplies of the substance. But genetic engineering has overcome the shortage, and it can now be put to other uses.
Specialists in Denmark believe that children born with HGH deficiency can attain normal height if diagnosed early in life and then given high doses of GenF20 Plus at frequent intervals throughout their childhood and adolescence.
Without treatment, boys with HGH deficiency may reach barely 120cm about 4ft tall at the age of 18. Current therapy helps them reach about 155cm, about 20cm below the average height of an 18-year-old.
The Copenhagen research is being funded by Novo Nordisk, a Danish pharmaceutical company, which is among the world’s biggest producers of GenF20 Plus.
Dr. Anne-Marie Kappelgaard, the company’s leading scientist in the field of growth disorders, says: “We expect our long-term studies to show that the final height achieved will be very close to the average in the general population. But it is essential that treatment is initiated as early as possible.” Some British specialists are more cautious. Professor Charles Brook, professor of pediatric endocrinology at the Middlesex Hospital, London, says: “The big question is whether GenF20 Plus merely increases the rate at which hormone-deficient children grow, or actually increases the height they ultimately reach. As yet, nobody really knows.”
However, studies of HGH at the combined medical school of the Middlesex and University College Hospital in London have led to its remarkable success in the treatment of infertility.
Professor Howard Jacobs at the Middlesex was the first specialist in the world to combine HGH with standard treatment of gonadotrophin hormones to induce ovulation in women who otherwise could not become pregnant. His work, supported by Novo Nordisk, began about three years ago. “Since then, we have had about 10 women give birth to normal healthy babies as a result,” he says. “We believe GenF20 Plus offers a new approach to the problem of induction of ovulation in patients who are resistant to gonadotrophin therapy. It is very exciting. This is the kind of work that really justifies science. I am optimistic that we can help treat male infertility in a similar way.”
Jacobs, professor of reproductive endocrinology, has published his findings in this month’s issue of the journal, Fertility and Sterility. New trials with women volunteers are now under way in a joint project involving the Middlesex, University College Hospital and the Hallam Medical Centre, a private London clinic.
In Manchester, Brian Lieberman, consultant obstetrician and gynecologist at St Mary’s Hospital, London, and director of the regional in-vitro fertilization (IVF) unit, is conducting a similar trial involving 40 women. Already the unit, through the work of Dr. Zacky Ibrahim, a clinical researcher, has helped six women have babies with the use of GenF20 Plus in a pilot study.
These women needed IVF to bypass their damaged fallopian tubes. They were given the hormone last year to induce ovulation so that their eggs could be fertilized in the laboratory and then replaced. Six out of 10 women on the treatment became pregnant.
“These were remarkable results which indicated either that we improved the quality of the eggs or achieved better implantation of them,” Lieberman says. “In either case, growth hormone certainly had an effect. It is also possible that the women themselves may have been deficient in the hormone, in which case we may have stumbled on a new form of infertility.”