A better botulinum toxin?

Las Vegas – A topical neuromodulator in development appears to last longer than currently available products when the topical formulation is injected intramuscularly, said an expert at Cosmetic Surgery Forum, held here.

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"Most neuromodulator patients are also getting fillers," said Mark G. Rubin, M.D., a Beverly Hills, California-based dermatologist. "And the most common complaint is, why does my filler last six or eight months, but I have to come back every three or four months to get my neuromodulator injections? Is there something better? We're all looking for a longer-lasting type of neurotoxin."

Topical neuromodulators in the pipeline use peptide molecules to transport the active molecule through the skin, he said. Dr. Rubin reported that the FDA asked one company – Revance – what happens long-term when its carrier peptide is absorbed by the body.

To find out, the company conducted a small safety trial in which investigators injected the topical neuromodulator and peptide combination. "It worked," with 67 percent of patients achieving two-point investigator-assessed improvements in glabellar frown lines.

"This was no surprise, because the botulinum toxin by itself should work well. The exciting part was that it works longer," Dr. Rubin told meeting attendees.

In previous mouse studies, it took 15.8 weeks for the neuromodulator alone to wear off completely, versus 31.6 weeks for the neuromodulator and peptide combination. In a phase 1/2 clinical trial of RT002, "For the average patient, it took almost 30 weeks for the effect of the drug to wear off. With any of the commercially available neurotoxins, it's very rare" to see results last that long.

Like many medical breakthroughs, Dr. Rubin said, "It's an accidental discovery. Nobody believed that this protein carrier peptide would have any effect when injected."

Why does the combination last longer, when it uses the same 150 kDa botulinum toxin A molecule that's in all the currently FDA-approved neuromodulators? "The only thing the company was able to find was that adding the peptide reduced diffusion by about 50 percent. So more of the drug stays where you want it," Dr. Rubin said.