Promotion of anagen, increased hair density and reduction of hair fall in a clinical setting following identification of FGF5-inhibiting compounds via a novel 2-stage process

Abstract

Background: There are very few effective, scientifically validated treatments with known mechanisms of action for treatment of hair loss in both men and women. Fibroblast growth factor 5 (FGF5) is an important factor in the irreversible transition from anagen to catagen, and inhibition of FGF5 prolongs anagen phase and reduces hair loss.

Objective: We aimed to screen botanically derived molecules for FGF5 inhibitory activity in vitro and assess efficacy in a clinical setting.

Methods: We screened for FGF5 inhibitory efficacy via a novel 2-step in vitro pipeline consisting of an engineered FGF5 responsive cell line, followed by an activated dermal papillae (DP) cell method. Efficacy in a clinical setting was assessed in a randomized, single-blind, placebo-controlled trial against early- to mid-stage pattern hair loss in men and women.

Results: We observed FGF5 inhibitory activity for a number of compounds from the monoterpenoid family, many showing greater inhibitory efficacy than our previously reported crude plant extracts. Evaluation of a lead candidate in a clinical study over 112 days showed a significant improvement in anagen:telogen (AT) ratio (p = 0.002), reduced hair fall (p = 0.007) and improved visual grading (p = 0.004). Scientifically matched photography on a subgroup of randomly chosen participants highlighted significant improvement in hair density, with increases evident in all tested participants compared to baseline.

Conclusion: Isolates from the monoterpenoid family displayed efficacy in FGF5 inhibition in vitro. A topical formulation containing a leading isolate significantly improved AT ratio, reduced hair fall and increased apparent hair density in the tested population of men and women.

Keywords: FGF5; anagen; hair growth; hair loss; hair treatment; in vitro testing.

Figure 1

The generalized structure of the monoterpenoid family. Notes: In those compounds which we tested for significant FGF5 inhibitory activity: R₁ is hydrogen, hydroxyl or oxygen; R₂ is absent or hydrogen or hydroxyl; X is CH₃ or CH₂OH or X is CH₂CH₂ or CHOHCH₂ and X and Y together form a single bond within a 6-membered ring; Y is CH₂ when X is CH₃ or CH₂OH or Y is CH or COH when X is CH₂CH₂ or CHOHCH₂ and Z is a saturated or unsaturated C₂–C₅ alkyl or alkyl ester. Abbreviation: FGF, fibroblast growth factor.

Figure 2

The Hamilton–Norwood (H-N) and Ludwig (L) scale ranges used in the study for men and women, respectively.

Figure 3

In vitro FGF5 inhibitory efficacy from the engineered BaF3 cell line assay. Notes: (A) Significant differences in inhibitory efficacy were observed, ANOVA p = 0.016. Post hoc pairwise comparisons identified specific differences: MTP3 vs. SO extract p = 0.002; MTP3 vs. MTP4 p = 0.013; MTP3 vs. MTP5 p = 0.036 and MTP3 vs MTP6 p = 0.002. Borderline significant results were also observed between MTP3 vs. EPT extract p = 0.065; EPT extract vs. SO extract p = 0.060 and EPT extract vs. MTP6 p = 0.065. The unit of measurement in the y axis is a ratio reflecting the fold difference between non-specific IC₅₀ and specific FGF5 inhibitory IC₅₀ (or IC₅₀ for IL-3/IC₅₀ for FGF5). This ratio is referred to as inhibitory efficacy. (B) Example inhibitory efficacy curve for 1 experiment using MTP5 showing inhibition of FGF5-stimulated cell growth at lower compound concentrations compared to controls using IL-3-dependent proliferation. Abbreviations: FGF, fibroblast growth factor; ANOVA, analysis of variance; EPT, eucalyptus essential oil; SO, Sanguisorba officinalis; IL, interleukin.

Figure 4

Recovery of anagen phase as indicated by ALP activity measured after treatment of DP cells with increasing concentrations of test compounds in the presence of FGF5. Notes: (A) MTP3 showed the highest recovery of anagen phase with respect to baseline and was more effective than EPT extract and much more effective than SO extract and the other MTP isolates. (B) Example of a dose–response curve from the ALP anagen recovery assay using mean values from each EPT extract experiment. Abbreviations: ALP, alkaline phosphatase; DP, dermal papillae; FGF, fibroblast growth factor; EPT, eucalyptus essential oil; SO, Sanguisorba officinalis.

Figure 5

Follicles in anagen phase from baseline to day 112. Notes: No difference was observed in the placebo group (A); however, differences were observed in between baseline and day 112 for both 0.095% MTP3 (p = 0.002) (B) and 0.5% MTP3 (p = 0.03) (C), with a number of study participants recovering to levels close to 80% anagen for the treatment groups. (D) Compared to baseline (indicated with dotted line at log2 zero), the majority of participants on both treatment arms showed improvement in anagen ratio at day 112. The placebo group had no trend in either direction.

Figure 6

Hair fall comparisons within treatment groups and between treatment groups. Notes: (A) No difference in hair fall was observed in the placebo group, although there was a trend for decreased hair fall at day 56 (p = 0.08). (B) In the 0.095% MTP3 treatment group, significant reductions in hair fall were observed between baseline and day 56 (p = 0.004) and between baseline and day 112 (p = 0.007). (C) In the 0.5% MTP3 treatment group, significant reductions in hair fall were observed between baseline and day 56 (p = 0.029) and between baseline and day 112 (p = 0.013). (D) Compared to placebo, significant differences in hair fall relative to baseline at day 112 were observed for 0.095% and 0.5% MTP3 formulations (p = 0.002 and 0.019, respectively), with both showing decreased hair fall. The line at 0 indicates no change relative to baseline on the log2 scale.

Figure 7

Visual grading scores within groups over the treatment course and between groups at day 112. Notes: (A) No differences were observed in the placebo group over time. (B) In the 0.095% MTP3 treatment group, significant differences were observed between day 112 vs. baseline (p = 0.002) and day 112 and day 56 (p = 0.003). (C) In the 0.5% MTP3 treatment group, significant differences were observed between day 112 vs. baseline (p = 0.016) and day 122 and day 56 (p = 0.020). (D) The 0.095% MTP3 performed significantly better compared to baseline than placebo (p = 0.0005). The 0.5% MTP3 group also performed better than placebo at day 112 (p = 0.012). The line at y axis = 0 indicates no change from baseline.

Figure 8

Scientifically matched photography compared to baseline. Notes: There was a significant increase in digital grading between day 56 and 112 (p = 0.030), and both time points displayed increased hair density from baseline for all participants for whom this assessment was performed. Line at 0 is indicative of “no change” in the log2 scale.