Efficacy of hydroquinone-free skin-lightening cream for photoaging

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1 Original Contribution Journal of Cosmetic Dermatology, 12, Efficacy of hydroquinone-free skin-lightening cream for photoaging Frank Dreher, PhD, 1 Zoe D. Draelos, MD, 2 Michael H. Gold, MD, 3,4 Mitchel P. Goldman, MD, 5 Sabrina G. Fabi, MD, 5 & Mary L. Puissegur Lupo, MD 6 1 Neocutis, Inc., San Francisco, CA, USA 2 Duke University School of Medicine, Department of Dermatology, Durham, NC, USA 3 Gold Skin Care Center, Nashville, TN, USA 4 Tennessee Clinical Research Center, Nashville, TN, USA 5 Goldman Butterwick Fitzpatrick Groff & Fabi, Cosmetic Laser Dermatology, San Diego, CA, USA 6 Lupo Center for Aesthetic & General Dermatology, New Orleans, LA, USA Summary Background Hyperpigmentation and solar damage remains a difficult problem to treat with topical agents. Aims To evaluate a novel skin-lightening complex (SLC) comprising four actives targeting melanin formation at multiple levels, namely disodium glycerophosphate, L-leucine, phenylethyl resorcinol, and undecylenoyl phenylalanine, in an oil-in-water emulsion cream. Patients Methods Skin-lightening complex was evaluated in 80 female subjects of skin types I III with at least moderate mottled hyperpigmentation. After a wash-out period of 1 month with a sunscreen, the subjects added a cream containing the SLC for 12 weeks twice daily to entire face and continued the sunscreen use. Results Whereas there was no significant change during the wash-out period, the primary endpoint mottled hyperpigmentation decreased by 32% after the 12-week treatment period with the SLC cream. Secondary endpoints such as severity and number of lentigines, skin tone, and skin brightness also improved. In all, 57% of the subjects showed at least a moderate response, 17% did not improve, and 3% got worse after the treatment. Conclusions The SLC cream was well tolerated, in particular when comparing with exfoliating or peeling agent containing skin-lightening products. When used with a daily sunscreen, this study confirms that the SLC represents an alternative to hydroquinone, retinoids, and many other skin-lightening actives. Keywords: skin lightening, skin tone management, anti-aging, melanin, mottled hyperpigmentation, lentigines, tyrosinase Introduction Irregular skin pigmentation of the face is the most common sign of photo-aging along with fine lines and Correspondence: F Dreher, Neocutis, Inc., 3053 Fillmore Street #140, San Francisco, CA 94123, USA. frank.dreher@neocutis.com Accepted for publication October 17, 2012 wrinkles. Irregular skin pigmentation can be induced by chronic exposure to ultraviolet radiation from sunlight and is mostly visible as mottled hyperpigmentation and lentigines. Eumelanin and pheomelanin are the pigment of skin and provide skin with its characteristic color. Both melanin forms are synthesized in the melanosome by enzymatic conversion of the amino acid L-tyrosine by tyrosinase. L-Tyrosine originates from the active uptake Wiley Periodicals, Inc.

2 of L-tyrosine by an amino acid transporter protein into the melanosome. 1,2 More recent evidence indicates L-phenylalanine as a second precursor for melanin formation. 3 After active uptake into the cytosol of the melanocyte by a similar transporter protein, L-phenylalanine is converted into L-tyrosine under the control of epidermal phenylalanine hydroxylase in a calciumdependent process. 3 Once the melanosome is packed with melanin after its maturation, the melanosome is transferred from the melanocyte into the keratinocyte in a complex process. 4 While cellular signals induced during or after contact are not yet fully understood, physical contact between melanocytes and keratinocytes is a prerequisite for melanosome transfer to occur. 5 Melanocyte keratinocyte adhesion is mediated by E-cadherin, a calcium-dependent transmembrane glycoprotein. Well established is the fact that melanin formation is stimulated by sun. Exposure to solar ultraviolet light results in release of α-melanocyte-stimulating hormone (α-msh) by keratinocytes. α-msh binds melanocortin 1 receptor (MC1R) on the surface of melanocytes, and thereby modulates melanin synthesis through activation of a camp-dependent protein kinase A pathway. 6 Clinical studies have established that topical hydroquinone and some retinoids are effective in improving pigmentation changes in subjects with photodamaged skin. 7 Numerous other actives including kojic acid-containing products have been also described for topical treatment of skin pigmentation. 7 While the safety of hydroquinone continues to be debated, 8 and topical retinoids frequently lead to local cutaneous reactions, 9 most alternative actives including retinoids seem significantly less efficient than hydroquinone, 10 may be less suited for continued use due to limited skin tolerability leading to a low rate of compliance, or would need further study before they could be recommended. This study presents a hydroquinone, retinoid, and alpha- or beta-hydroxy acid-free approach in skin lightening by not only focusing on the inhibition of melanin biosynthesis via control of tyrosinase, but additionally also addressing the supply of L-tyrosine into the melanocyte, the melanosome transfer, and the sun-induced activation of tyrosinase via α-msh. 11 The skin-lightening cream containing a proprietary complex targeting different steps in the pathway of melanin formation was studied in females of skin types I III with mottled hyperpigmentation. This skin-lightening complex (SLC) was effective in improving skin tone in women with epidermal melasma, 11 and has been shown to provide a comparable efficacy to a 4% hydroquinone lightening cream in the treatment of melasma as compared with a triple formulation containing 4% hydroquinone, tretinoin, and a steroid. 12 Patients & methods Study design In a four-center study approved by the Independent IRB (Plantation, FL), eighty female subjects between 35 and 65 years of age (53 7 years) of skin types I III (I: 9%, II: 67%, III: 24% of subjects) with at least mild mottled hyperpigmentation (corresponding to score 2 on the mottled hyperpigmentation scale) were included. Whereas subjects with dermal or mixed epidermal and dermal melasma (as assessed with the Wood s lamp) and with post-inflammatory hyperpigmentation (due to acne or other causes) were excluded, the presence or severity of solar lentigines was not a criteria for inclusion or exclusion. The subjects were of good general health, had no obvious skin disease, precancerous skin lesions, or known history of atopic dermatitis, psoriasis, rosacea, seborrheic dermatitis, hypertrophic skin scarring, or skin cancer on the face, and were free of acne and without a recent history of acne, and had no acne-prone facial skin at the time of inclusion. Only subjects not using topical products with skinlightening actives (including arbutin, azelaic acid, hydroquinone, kojic acid, licorice extracts, bearberry extracts, mequinol, etc.), alpha-hydroxy (glycolic acid, etc.) and beta hydroxy acids (salicylic acid, etc.), concentrated (>1%) vitamin C products, steroids, retinoids, or not undergoing light-to-medium peels or microdermabrasion for 2 weeks were included. Subjects receiving laser, light or radio-frequency treatments within 3 months, taking oral retinoids, undergoing dermabrasion, or having greater than 20% TCA peels 6 months prior to inclusion were further excluded. The study further excluded pregnant or nursing women and women planning a pregnancy within the study period. The subjects were allowed to continue use of regular make-up. The study was realized between fall 2010 and spring After a wash-out period of 4 weeks with a SPF30 sunscreen (Journee Bio-restorative Day Cream; Neocutis, Inc., San Francisco, CA, USA) applied in the morning, the subjects additionally applied twice daily the study cream containing 5% of the proprietary SLC called Melaplex (Neocutis, Inc.) to the entire face. This complex contained with disodium glycerophosphate, L-leucine, phenylethyl resorcinol and undecylenoyl phenylalanine all chemicals of a relative small molecular weight of less than 500 g/ mol, what indicates that those chemicals are able to penetrate skin. 13 The sunscreen provided also some UVA 2013 Wiley Periodicals, Inc. 13

3 protection (k c = 371 nm). The subjects were instructed to continue to apply the sunscreen in the morning about 15 min after application of the skin-lightening cream. Before each application, the subjects were asked to wash their face with a gentle cleanser (NeoCleanse Gentle Skin Cleanser; Neocutis, Inc.). This skincare regimen was followed for a period of 12 weeks. The facial skin of the subjects was evaluated by the clinical investigators before the wash-out period, after the wash-out period (week 0), and at 4-, 8-, and 12- week treatment with the skin-lightening cream. The evaluations included: Clinical photography under standardized position (i.e., constant distance from camera at three constant angles for full-frontal, right, and left half-face) and lighting conditions of the cleansed face. Assessment of the primary efficacy outcome measure mottled hyperpigmentation on a 5-point visual scale (0 = none, 1 = minimal, 2 = mild, 3 = moderate, 4 = severe) as described by S. Kang and associates in a multi-center trial of a tazarotene 0.1% cream in the treatment of photodamage. 14 Assessment of the secondary efficacy outcome measures lentigines (0 = none, 1 = minimal, 2 = mild, 3 = moderate, 4 = severe), irregular depigmentation (0 = none, 1 = minimal, 2 = mild, 3 = moderate, 4 = severe), skin tone (0 = even color over entire face, 1 = even color over almost entire face, 2 = uneven color in some areas but in less than about ¼ of face, 3 = uneven color in between about ¼ to ¾ of face, 4 = uneven color in more than ¾ of face), skin brightness and radiance (0 = bright/radiant over entire or almost entire face, 1 = bright/radiant over majority of face, 2 = bright/radiant areas and dull areas about equal, 3 = more dull than bright/radiant areas, 4 = mostly dull areas, 5 = very dull); and count of small (diameter smaller than about 1/8 inch) and large (larger than about 1/8 inch) solar lentigines. Global response assessment from baseline using a 7- point scale (0 = complete response (complete resolution of photodamage), 1 = almost complete response (approximately 90% improvement), 2 = marked response (approximately 75% improvement), 3 = moderate response (approximately 50% improvement), 4 = slight response (approximately 25% improvement), 5 = no response, 6 = condition worsened). Assessment of local tolerability including erythema, burning/stinging, pruritus, dryness, peeling, atrophy, and telangiectasia using the 4-point scale: 0 = none, 1 = mild, 2 = moderate, and 3 = severe. In addition, the subjects were asked to report improvements and satisfaction with the treatment after the wash-out period and after the 12-week treatment period using a questionnaire. Statistical analysis was performed with statistical software SigmaPlot Version 11.0 (Systat Software, Inc., Chicago, IL) using Kruskal Wallis one-way analysis of variance on ranks. Data for number of age spots failed the normality test by Shapiro-Wilk and were therefore also analyzed with Kruskal Wallis one-way analysis of variance on ranks. Data was compared before washout and during the 12-week treatment period with the skin-lightening cream. A P-value smaller than 0.05 was regarded as statistically significant. Results The study was completed by 75 of the 80 subjects enrolled. Two subjects were lost during the wash-out period and three subjects were lost to follow-up after starting the skin-lightening cream. Of the subjects who completed the study, all subjects made all five study visits except two subjects who each missed a single visit at week 4. No subject was lost or missed a visit due to adverse events. At inclusion (before start of wash-out period), all subjects had at least mild mottled hyperpigmentation in the face corresponding to a score of at least 2 (median = 3). Severity of mottled hyperpigmentation significantly decreased by 32% from (mean SD) [median = 3; ranging from 2 to 4] before the treatment (after wash-out period) to [2; 0 4] after the 12-week treatment period with the skin-lightening cream. The difference reached statistical significance after 8 weeks (decrease of 23% to ; median = 2). Mottled hyperpigmentation did not change significantly during the 4-week wash-out period with the sunscreen. Improvement by at least one grade on the 5-point mottled hyperpigmentation scale was observed in 13%, 51%, and 63% of the subjects after 4, 8, and 12 weeks, respectively. Severity of lentigines significantly decreased by 23% from [3; 1 4] to [2; 0 4] after the 12-week treatment period. Similarly, the number of small age spots significantly decreased by 41% from to after the 12-week treatment period with the skin-lightening cream. The number of large lentigines decreased by 9%, but did not reach statistical significance. Whereas irregular depigmentation decreased by 30% after 12 weeks, this difference did not also reach statistical significance. Skin tone and skin brightness/radiance both significantly improved by Wiley Periodicals, Inc.

4 Worse No Slight At least moderate (a) 100% 90% 80% 3% 21% 17% 34% Subjects 70% 60% 50% 40% 23% 34% 46% 30% 20% 57% 45% 10% 20% 0% Week 4 Week 8 Week 12 Figure 1 Percentage of subjects with at least moderate, slight, or with no improvement, or who got worse as a function of treatment time with skin-lightening complex (SLC). 18% (from [3; 1 4] to [2; 1 4]) and 32% (from [3; 1 4] to [2; 1 4]), respectively, after the 12-week treatment period with the skin-lightening cream. No significant changes were observed during the wash-out period with the sunscreen. The global response assessment from baseline by the clinical investigator indicated that an increasing percentage of subjects improved with treatment time (Fig. 1). Twenty percent of the subjects showed at least a moderate response after 4 weeks, 45% after 8 weeks, and 57% at the end of the 12-week treatment period. Using a questionnaire, a majority of the subjects observed improvements in hyperpigmentation after the 12-week treatment period. Very much or much improvement was reported by 35%, slight improvement by 45%, and no improvement by 20% of the subjects. Furthermore, a majority were satisfied with the treatment after the 12 weeks; 56% were very satisfied or satisfied, 31% were slightly satisfied, and 13% were not satisfied. Figure 2 provides clinical photography of two representative subjects before and after the 12-week treatment period, and illustrates the significantly improved appearance of skin tone when using the skin-lightening cream for 12 weeks twice daily in combination with the study sunscreen. The test products were generally well tolerated as assessed by the investigators (Table 1). Whereas a few subjects had visible erythema and telangiectasia before starting the wash-out period, those signs appeared not to get worse during the treatment with the skin-lightening product in combination with the sunscreen. In fact, the frequency of subjects with erythema and telangiectasia decreased at the end of the 12-week (b) Figure 2 Clinical photography of two subjects before (after a 4- week wash-out period with daily sunscreen) and after the use of skin-lightening complex (SLC) for 12 weeks with daily sunscreen. Permission for reproduction of the photos was obtained by both subjects. treatment period. The incidence of dryness increased after using the SLC for 4 weeks, but became comparable to the incidence during the wash-out period with prolonged use. The incidence of burning/stinging slightly increased after 4 and 8 weeks as compared with the wash-out, but burning/stinging was not reported after 12 weeks. Whereas the incidence of peeling slightly increased when using the skin-lightening product, pruritus was hardly reported during the entire study. There was no evidence that the twice-daily use of the SLC over 12 weeks caused atrophy under the present study conditions. In addition to the intolerabilities listed in Table 1, adverse events possibly related to the treatment regimen consisting of skin cleanser, lightening cream, and sunscreen included mild acne in six subjects (7.5%, n = 80), facial rash in one (1.3%), and moderately watery eyes in one subject (1.3%). During the entire 2013 Wiley Periodicals, Inc. 15

5 Table 1 Skin tolerability as assessed by the clinical investigators; percentage of subjects with local intolerabilities during wash-out and 12-week treatment phase study, 13 additional adverse events were reported, which were regarded as not treatment-related. Using a questionnaire, 89.3% of the subjects reported to tolerate the test product very well without discomfort or well with hardly any discomfort, while the rest felt barely noticeable temporary discomfort (5.3%), or well noticeable temporary discomfort to significant discomfort (5.3%) after 12 weeks. Discussion Wash-out phase Before (n = 80) After (n = 78) Treatment phase 4 weeks (n = 76) 8 weeks (n = 75) Erythema Burning/ Stinging Pruritus Dryness Peeling Atrophy Telangiectasia weeks (n = 75) The clinical study with eighty female subjects with photodamage demonstrated that SLC is effective in improving signs of facial skin discolorations including mottled hyperpigmentation, skin tone, and appearance of solar lentigines when used together with daily sun protection. The trial included a 1-month wash-out period with the study sunscreen where no significant changes were observed. The SLC comprised the following four complementary actives each targeting a different step in the pathway of melanin formation as judged from in vitro data: Disodium glycerophosphate targets the calciumdependent processes L-tyrosine formation from L-phenylalanine and melanosome transfer. Glycerophosphates, via their twice negatively charged phosphate group, have a high affinity for small and high charged cations such as the calcium ion (Ca 2+ ) through attractive electrostatic forces. As previously discussed, calcium has been recognized as an important regulator of melanin formation. In principle, disodium glycerophosphate limits melanosome transfer through its calcium sequestering properties. 5 Disodium glycerophosphate may further decrease uptake and conversion of L-phenylalanine into L-tyrosine in the melanocyte, which is also a calcium concentration-dependent process. 3 L-Leucine is a competitive inhibitor of tyrosine uptake into melanocytes and melanosomes 1,2 and was shown to inhibit melanin formation. 15 Phenylethyl resorcinol (4-(1-phenylethyl) 1,3-benzenediol) is a potent inhibitor of tyrosinase and was shown to be at least 10-times more efficient than kojic acid in a pigmented 3-dimensional epidermal model. 16 Undecenoyl phenylalanine (N-undecyl-10-enoyl-Lphenylalanine) is an antagonist of α-msh and was shown to inhibit melanin formation in melanocytes stimulated with UVB. 17 In a previous clinical study in twenty females with epidermal melasma, the same complex was shown to reduce melasma area and severity by 43% after 12 weeks twice-daily use with a sunscreen. 11 For comparison, mottled hyperpigmentation improved (by at least one unit) in 74% of the subjects after 24 months with a 0.05% tretinoin cream, whereas significant improvement was observed after 4 months. 18 Thirty percent of the subjects experienced treatment related adverse events affecting skin. While the hyperpigmentation evaluation was performed with a 10-point severity score, the study also included a daily sunscreen. Another study with a 0.1% tazarotene cream resulted in improvement of mottled hyperpigmentation (by at least one unit) in about 70% of the subjects after 12 weeks (percentage estimated from Fig. 2B) and of 87% after 24 weeks. 14 This evaluation was performed with the identical 5-point visual scoring system as used in the present study. Forty-two percent of the subjects reported desquamation, 37% erythema, and 21%, burning. Whilst the study was placebo-controlled, the subjects also used a sunscreen. Numerous marketed skin-lightening and lightening products contain ingredients with exfoliating properties such as alpha hydroxy acids (e.g.: glycolic acid, lactic acid). While exfoliation is an accepted method to eliminate melanin from skin and help lighten skin, 19 administration of leave-on products with exfoliating ingredients can cause significant skin discomforts, such as burning and stinging, skin irritation, peeling, and dryness. For instance, about two-third of the subjects experienced irritation using a skin-lightening cream comprising glycolic acid and retinol in combination with the tyrosinase inhibitor methyl dihydroxybenzoate for 8 weeks. 20 In addition, one study reported on the treatment of facial hyperpigmentation with a combination of 2% kojic acid and 5% glycolic acid. 21 In this study, all patients experienced discomforts including burning, stinging, redness, and desquamation; and a few patients Wiley Periodicals, Inc.

6 had to discontinue due to side effects. It has been recognized that repeated use of glycolic acid products makes skin more sensitive to sun, 22 which may enhance suninduced photodamage 23 and lead to an increase in pigmentation even in the absence of noticeable irritation. 24 The present study has some significant limitations, however. The study lacked a control group such as a placebo and the sunscreen may have contributed to the study outcome. In addition, the evaluations were realized using subjective measures (i.e., visual assessments) and not objective measures such as the recently described UV light-enhanced visualization method for the assessment of the area and darkness of solar lentigines. 25 References 1 Pankovich JM, Jimbow K. Tyrosine transport in a human melanoma cell line as a basis for selective transport of cytotoxic analogues. Biochem J 1991; 280: Potterf SB, Muller J, Bernardini I et al. Characterization of a melanosomal transport system in murine melanocytes mediating entry of the melanogenic substrate tyrosine. J Biol Chem 1996; 271: Schallreuter KU, Wood JM. The importance of L-phenylalanine transport and its autocrine turnover to L-tyrosine for melanogenesis in human epidermal melanocytes. Biochem Biophys Res Commun 1999; 262: Van Den Bossche K, Naeyaert JM, Lambert J. The quest for the mechanism of melanin transfer. Traffic 2006; 7: Joshi PG, Nair N, Begum G et al. Melanocyte-keratinocyte interaction induces calcium signalling and melanin transfer to keratinocytes. Pigment Cell Res 2007; 20: Rouzaud F, Kadekaro AL, Abdel-Malek ZA et al. MC1R and the response of melanocytes to ultraviolet radiation. Mutat Res 2005; 571: Solano F, Briganti S, Picardo M et al. Hypopigmenting agents: an updated review on biological, chemical and clinical aspects. Pigment Cell Res 2006; 19: Levitt J. The safety of hydroquinone: a dermatologist s response to the 2006 Federal Register. J Am Acad Dermatol 2007; 57: Mukherjee S, Date A, Patravale V et al. Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety. Clin Interv Aging 2006; 1: Draelos ZD. Skin lightening preparations and the hydroquinone controversy. Derm Ther 2007; 20: Gold MH, Biron J. Efficacy of a novel hydroquinone-free skin-brightening cream in subjects with melasma. J Cosmet Dermatol 2011; 10: Monheit GD, Dreher F. Comparison of a skin lightening cream targeting melanogenesis on multiple levels to triple combination cream for melasma. J Drugs Dermatol 2013; 12. (accepted for publication). 13 Bos JD, Meinardi MMHM. The 500 Dalton rule for the skin penetration of chemical compounds and drugs. Exp Dermatol 2000; 9: Kang S, Krueger GG, Tanghetti EA et al. A multicenter, randomized, double-blind trial of tazarotene 0.1% cream in the treatment of photodamage. J Am Acad Dermatol 2005; 52: Ishikawa M, Kawase I, Ishii F. Combination of amino acids reduces pigmentation in B16F0 melanoma cells. Biol Pharm Bull 2007; 30: Vielhaber G, Schmaus G, Jacobs K et al. 4-(1-Phenylethyl) 1,3-benzenediol: a new, highly efficient lightening agent. IFSCC Magazine 2006; 9: Stoltz C, Garcia C. Use of a compound inactivating the kinase A protein in a composition containing a cosmetically acceptable medium in order to lighten the skin. United States Patent Application. 2005/ Kang S, Bergfeld W, Gottlieb AB et al. Long-term efficacy and safety of tretinoin emollient cream 0.05% in the treatment of photodamaged facial skin: a two-year, randomized, placebo-controlled trial. Am J Clin Dermatol 2005; 6: Berson DS, Cohen JL, Rendon MI et al. Clinical role and application of superficial chemical peels in today s practice. J Drugs Dermatol 2009; 8: McDaniel DH, Wu J. Efficacy of a natural-based bleaching cream versus hydroquinone 4% bleaching gel in the treatment of hyperpigmentation. Cosmet Dermatol 2008; 21: Garcia A, Fulton JE Jr. The combination of glycolic acid and hydroquinone or kojic acid for the treatment of melasma and related conditions. Dermatol Surg 1996; 22: Kornhauser A, Wei RR, Yamaguchi Y et al. The effects of topically applied glycolic acid and salicylic acid on ultraviolet radiation-induced erythema, DNA damage and sunburn cell formation in human skin. J Dermatol Sci 2009; 55: Kaidbey K, Sutherland B, Bennett P et al. Topical glycolic acid enhances photodamage by ultraviolet light. Photodermatol Photoimmunol Photomed 2003; 19: Tsai TF, Bowman PH, Jee SH et al. Effects of glycolic acid on light-induced skin pigmentation in Asian and Caucasian subjects. J Am Acad Dermatol 2000; 43: Pierard GE, Seite S, Rougier A et al.analytic assessment under ultraviolet light of actinic lentigines under bleaching treatment. J Cosmet Dermatol 2011; 10: Wiley Periodicals, Inc. 17