Following disappointing phase 2b trial results with fispemifene in men with sexual dysfunction, California-based Apricus Biosciences has announced that it will suspend all clinical activities with the drug. Fispemifene is a once-daily orally administered selective estrogen receptor modulator (SERM) in development for several urological conditions in men.
In March, Apricus reported top-line results from a proof-of-concept study of fispemifene in men with secondary hypogonadism and sexual dysfunction. The randomized, double-blind, placebo-controlled trial evaluated the safety and tolerability of fispemeifene, as well as its ability to improve erectile function and low libido compared with placebo, in 160 men with secondary hypogonadism.
While fispemifene 450 mg demonstrated statistically significant improvements in total, percent free, and percent bioavailable testosterone compared with placebo (P < 0.0001 at four and eight weeks), the magnitude of these increases was not sufficient to achieve statistical significance for either the primary endpoint of erectile function or the secondary endpoint of low libido. Erectile function was assessed using the International Index of Erectile Function erectile function domain (IIEF-EF) questionnaire and Sexual Encounter Profile (SEP) diaries, and low libido/desire was assessed using the Psychosexual Daily Questionnaire (PDQ).
Fispemifene acts in secondary hypogonadism by inhibiting the negative feedback of testosterone production via an estrogen-blocking effect at the level of the pituitary, resulting in increased testosterone production in the testes. This, in turn, restores circulating testosterone levels to within, but not beyond, the normal range.
Apricus has slashed its employment, including members of its executive team, by 30% and is focusing its efforts on developing a cream for erectile dysfunction (Vitaros), the company announced. Apricus plans to resubmit a new drug application to the FDA for Vitaros in the third quarter of 2016, and hopes to win approval in 2017.
Sales for erectile dysfunction products were $3 billion in the U.S. in 2014, according to data from IMS Health. It has been estimated that approximately 20 million men in the U.S. have some form of erectile dysfunction, with more than half a million diagnosed each year.
Sources: BioSpace; April 6, 2016; GlobeNewswire; March 28, 2016; and Fispemifene; 2016.