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CHICAGO – Deoxycholic acid injections benefit patients on either end of the spectrum with mild or extreme submental fat, a phase III safety study shows.
“What this study shows is that the applicability of the product is wider than what’s represented in the registration trials because they looked at a very narrow band and this includes people with very mild and extreme [submental fat],” Dr. Richard G. Glogau of San Francisco Dermatology and the University of California, San Francisco, said in an interview. He presented the results of the study at the annual meeting of the American Society for Dermatologic Surgery.
Deoxycholic acid gained U.S. approval in April 2015 as the first injectable cytolytic drug to treat moderate to severe convexity or fullness associated with submental fat (SMF) in adults. It is marketed as Kybella.
Dr. Richard G. Glogau
Because treatment can be tailored based on the amount and thickness of SMF, the study sought to evaluate deoxycholic acid 2 mg/cm2 or placebo for up to six treatments 1 month apart in 47 patients with mild SMF and 46 patients with extreme SMF based on Clinician-Reported Submental Fat Rating Scale (CR-SMFRS) scores of 1 (mild) or 4 (extreme).
The predominantly female cohort had an average age of 48 years in the mild SMF group and 51 years in the extreme SMF group and a mean body mass index of 25 kg/m2 and 32.5 kg/m2, respectively. About 30% of patients in the extreme SMF group had moderate to severe skin laxity compared with about 15% in the mild SMF group.
The mean number of treatment sessions was 4.9 for placebo and 4.2 for deoxycholic acid in the mild SMF group, and 5.6 for placebo and 4.9 for deoxycholic acid in the extreme SMF group.
“I don’t think in the real world that’s our experience,” Dr. Glogau said at the meeting. “People in the mild group get by with much less and, conversely, people at the extreme end would be happy to go on higher than four or five treatments, depending on what size they started with.”
The mean total injection volume across all treatments was 17.2 mL, 13.9 mL, 38.4 mL, and 31.6 mL, respectively, which is consistent with the need for less product in mild SMF.
In the mild SMF group, SMF was reduced by one grade in significantly more patients following deoxycholic acid treatment than placebo as measured with the CR-SMFRS (74.2% vs. 20%), the Patient-Rated SMFRS (67.7% vs. 33.3%), or a composite of the two scales (61.3% vs. 6.7%).
The percentages of patients with extreme SMF achieving a one-grade improvement with deoxycholic acid were even higher: CR-SMFRS (96.4% vs. 26.7%), PR-SMFRS (89.3% vs. 46.7%), or the composite (89.3% vs. 13.3%), said Dr. Glogau.
Moreover, SMF improved by two grades on the composite endpoint in 43% of extreme SMF patients treated with deoxycholic acid vs. 0% given placebo. P values for all comparisons were less than .05.
“To reach a two-grade change in virtually anything you want to study is difficult to achieve, so I think this is a significant landmark that came out of this study,” Dr. Glogau said.
Significantly more deoxycholic acid–treated patients also reported being satisfied with the appearance of their face and chin compared with those given placebo in the mild SMF (80% vs. 46.7%; P less than .05) and extreme SMF (71.4% vs. 0%; P less than .05) groups.
Despite reductions in SMF, skin laxity was unchanged or got only slightly better from baseline in all patients on deoxycholic acid. This is not surprising, because deoxycholic acid exerts its killing effect on fat cells only, not on fibrous septae or the dermis, and skin laxity is a reflection of inherent elasticity in the dermis, together with the fibrous septae in the fat running between skin and muscle, Dr. Glogau explained.
Most adverse events were mild or moderate in severity and transient in nature, he said. Among mild SMF patients, pain was reported in 74% treated with deoxycholic acid vs. 50% with placebo, bruising in 48% vs. 50%, edema in 42% vs. 25%, numbness in 48% vs. 6%, and swelling in 42% vs. 13%. The percentages were generally similar in the extreme SMF group.
“I think the incidence of hematoma and bruising is actually a function of injection technique and numbers out in clinical practice are somewhat lower,” Dr. Glogau observed.
No drug-related serious adverse events were reported. Nerve paresis was reported in two deoxycholic acid–treated patients with mild SMF and resolved without sequelae after 4 days and after 52 days.
