BUENOS AIRES (Reuters Health) - The first three patients undergoing a "revolutionary" phase I human gene therapy trial for erectile dysfunction have not developed any treatment-related adverse events, according to preliminary results released here this week at the 11th World Congress of the International Society for Sexual and Impotence Research.
A phase II trial might start by the end of 2005 and the therapy might reach the clinical setting "within next 7 to 8 years", said lead author Dr. Albert Melman, of the Albert Einstein College of Medicine in New York.
Dr. Melman and colleagues are testing the safety of a single intracavernous injection of the recombinant gene maxi-K. The trial was launched in the spring of 2004 at the Mount Sinai School of Medicine in New York.
Maxi-K channels in the cell membrane are involved in diminished smooth muscle contraction, which eventually leads to relaxation and erection.
Researchers used a "naked" DNA plasmid vector to deliver the recombinant gene. Naked DNA has been traditionally regarded as an unpopular vector, because of its lack of efficacy and limited duration of effect. But Dr. Melman's team chose it instead of a viral vector to minimize adverse effects and help overcome regulatory barriers.
All three volunteers were diagnosed with moderate to severe erectile dysfunction. They received injections of low doses of the product, so-called hMaxi-K. At 1- to 5-month follow-up, none of the men had developed side effects or had vector detected in semen samples, authors said.
According to Dr. Melman, six more patients will be recruited and tested by the end of this year. Eventually, about 400 patients will participate in clinical trials before the treatment is submitted for FDA approval.
The approach has already been tested successfully in rats with erectile dysfunction.
In humans, it is estimated that each dose will cost around $400 and boosts might be needed every 6 months.
"In the best case, the method will work by itself. On the other hand, you might be able to use lower doses of Viagra, Cialis or Levitra or improve their efficacy," Dr. Melman told Reuters Health.
"If it works, it will be revolutionary. Gene therapy will make medicine change in a very dramatic way", he added.
"Dr. Melman is a pioneer. If he succeeds, the whole field of gene therapy for erectile dysfunction will be stimulated," commented Dr. Néstor Gonzalez-Cadavid, an UCLA researcher who is studying the effects of another gene therapy for erectile dysfunction in rats. Dr. Gonzalez-Cadavid plans to begin his own clinical trials within next 2-3 years.
MeSH Headings: Biological Therapy : Clinical Trials : Congresses : Health Care Economics and Organizations : Environment and Public Health : Epidemiologic Methods : Evaluation Studies : Genetic Engineering : Genetic Techniques : Health : Health Occupations : Health Services Administration : Medicine : Investigative Techniques : Organizations : Population Characteristics : Preventive Medicine : Public Health : Quality of Health Care : Specialties, Medical : Therapeutics : Gene Therapy : Epidemiologic Study Characteristics : Clinical Trials, Phase I : Health Care Quality, Access, and Evaluation : Health Care Evaluation Mechanisms : Analytical, Diagnostic and Therapeutic Techniques and Equipment : Biological Sciences : Health Care