Dominic Burg, Masakuni Yamamoto, Masato Namekata, Joseph Haklani, Koichiro Koike, Maria Halasz

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