Comment
With the continued growth of the Latino population in the United States and likely higher prevalence of onychomycosis,9 this post hoc analysis provides important insights into treatment of onychomycosis in this patient population.
Efinaconazole solution 10% was significantly more effective than vehicle in the Latino population (P<.001) and also appeared significantly more effective than the non-Latino population across the 2 phase 3 studies (P=.012). Interestingly, complete cure rates (25.6%) were identical to those reported in the phase 2 study of Mexican patients treated with efinaconazole for 36 weeks.10 Specific data with other topical therapies, such as tavaborole, in Latino patients are not available. One phase 3 study of tavaborole for onychomycosis included 89 Mexican patients (15% of the total study population), but complete cure rates for the overall active treatment group were higher in a second phase 3 study (6.5% vs 9.1%) that did not include participants outside the United States or Canada.12
It is not clear why phase 3 efficacy results with efinaconazole appear better in the Latino population. There are a number of predisposing factors for onychomycosis that are important treatment considerations in Latinos. Obesity is an important factor in the development of onychomycosis,13 with more than 42% of Latino adults in the United States reportedly obese compared to 32.6% of non-Latino adults.14 Obese patients reportedly have shown a poorer response to efinaconazole treatment15; however, in our analysis, the mean weight of the 2 subpopulations was similar at baseline. Diabetes also is associated with an increased risk for onychomycosis16,17 and may be a more important issue in Latinos perhaps due to differences in health care access, social and cultural factors, and/or genetics, as well as the greater incidence of obesity. Prior reports suggest the efficacy of efinaconazole is not substantially influenced by the presence of diabetes,18 and in our 2 subpopulations, baseline incidence of coexisting diabetes was similar. These factors are unlikely to account for the better treatment success seen in our analysis. Efinaconazole has been reported to be more effective in females,19 though the reasons are less clear. The higher proportion of female Latinos (30.4% vs 21.3%) in our study may have had an impact on the results reported, though this baseline characteristic cannot be considered in isolation.
When considering the net effect (active minus vehicle), the apparent benefits of efinaconazole in Latino patients with onychomycosis were more marked. Vehicle complete cure rates at week 52 were 0% compared with 5.6% of non-Latino participants. Vehicle cure rates in randomized controlled trials of toenail onychomycosis are relatively low and appear to be independent of the study characteristics.20 Vehicle cure rates of 2 topical treatments—efinaconazole and tavaborole—reported in their 2 respective phase 3 studies were 3.3% and 5.5% for efinaconzole11 and 0.5% and 1.5% for tavaborole.12 It has been suggested that the higher results seen with the efinaconazole vehicle relate to the formulation, though there is no reason to expect it to perform differently in a Latino population. It also has been suggested that baseline disease severity might impact vehicle treatment outcome.20 In our analysis, the percentage affected nail at baseline was higher in the Latino participants treated with vehicle (38.9% vs 36.2%).
Although the overall level of AEs was similar in Latino versus non-Latino participants treated with efinaconazole, events were generally milder in the Latino subpopulation and fewer participants discontinued because of AEs.
Our study had a number of limitations. A study period of 52 weeks may be too brief to evaluate clinical cure in onychomycosis, as continued improvement could occur with either longer treatment or follow-up. Also, the pivotal studies were not set up to specifically study Latino participants; the demographics and study disposition may not be representative of the general Latino population.
Conclusion
Once-daily treatment with efinaconazole solution 10% may provide a useful topical option in the treatment of Latino patients with toenail onychomycosis.
Acknowledgment
The authors would like to thank Brian Bulley, MSc (Konic Limited, West Sussex, United Kingdom), for medical writing support. Valeant Pharmaceuticals North America LLC funded Konic Limited’s activities pertaining to this manuscript. Dr. Cook-Bolden did not receive funding or any form of compensation for authorship of this publication.
