Viagra faces stiff competition from gene therapy
been heralded by the successful completion of a Phase I clinical
trial of a new gene therapy which could provide six months' effect
with a single dose.
The gene therapy was found to be completely safe in a trial of 11 men administered with various doses. Even though the dosage levels were not designed to answer erectile dysfunction efficacy questions, significant members of the study reported clinically significant and sustained improvements. No adverse effects or side effects were observed in the test group.
If its early potential is backed up in further trials, the gene therapy could transform the market for ED treatments, currently dominated by blockbuster medications such as Pfizer's Viagra (sildenafil), Lilly ICOS' Cialis (tadalafil) and GlaxoSmithKline/Bayer's Levitra (vardenafil).
Talking to DrugResearcher.com, lead author of the recent work Professor Arnold Melman, chair of the Department of Urology at the Albert Einstein College of Medicine of Yeshiva University and founder of Ion Channel Innovations, said: "the therapy lasts for a long time and may work synergistically with Viagra or Cialis."
"The great thing about this therapy is that it allows for spontaneity and works well in ageing and diabetic models."
A Spectra Intelligence report entitled The World Market For Sexual Disorders has valued the world market for erectile dysfunction therapies at $2.3bn (€1.7bn).
Tim Atkinson, director of research and analysis at Spectra Intelligence told DrugResearcher.com: "current pharmacotherapies for erectile dysfunction range from oral, injectable and transurethral drug delivery routes but each has advantages and disadvantages over the other, which opens the market up for newer products to be developed with improved efficacy, reduced side-effect profiles and wider dosing choices."
"New drug therapies that effectively combat therapeutic deficiencies, unmet needs, or target patient preferences will undoubtedly succeed in the market place, and may propel the market to $5bn within a decade."
The new therapy involves a transfer gene called hMaxi-K, which opens the potassium ion channels in the smooth muscle cells of the penis when arousal signals are received. Professor Melman said: "when the ion-channel opens, it allows potassium ions to flow out of the cell, hyperpolarising the cell membrane, causing cell and therefore muscle relaxation."
This muscle relaxation leads to greater blood flow to the organ, allowing erection to occur. The mechanism also removes the riskof priapism, a side effect in which a painful erection lasting for more than four hours is induced. This can occur with existing drug treatments for ED.
Professor Melman believes that this relaxation of the smooth muscle cells could also be effective in treating overactive bladder disease by stopping the spasms that cause the condition, opening up another multibillion dollar market for the therapy.
He also said that the industry had "met resistance with gene therapy - as viral vectors have been known to cause problems. However, this naked DNA vector which we have used goes into a smaller percentage of cells and doesn't integrate with chromosomal DNA."
Professor Melman continued: "Our next target is raise enough money for the phase one trials of this therapy for overactive bladder disease before entering into stage two trials for erectile dysfunction."
