A phenotypic screening platform utilising human spermatozoa identifies new compounds with contraceptive activity

Abstract

24There is an urgent need to develop new methods for male contraception, however a major barrier to drug discovery 25 has been the lack of validated targets and the absence of an effective high-throughput phenotypic screening system. To 26 address this deficit, we developed a fully-automated robotic screening platform that provided quantitative evaluation 27 of compound activity against two key attributes of human sperm function: motility and acrosome reaction. In order to 28 accelerate contraceptive development, we screened the comprehensive collection of 12,000 molecules that make up 29 the ReFRAME repurposing library, comprising nearly all the small molecules that have been approved or have undergone 30 clinical development, or have significant preclinical profiling. We identified several compounds that potently inhibit 31 motility representing either novel drug candidates or routes to target identification. This platform will now allow for 32 major drug discovery programmes that address the critical gap in the contraceptive portfolio as well as uncover novel 33 human sperm biology. 34 35 36 Introduction. 38An effective and comprehensive family planning strategy is fundamental to delivery on the United Nations 17 39 Sustainable Development Goals (Starbird et al., 2016; Goodkind et al., 2018), however the current contraceptive 40 portfolio is suboptimal. For example, it is estimated that more than 214 million women in developing countries have an 41 unmet need for contraception which results in 89 million unintended pregnancies and 48 million abortions every year, 42 with substantial impacts on maternal and child health and poverty levels (Guttmacher Institute, 2017). To achieve the 43 UN targets it is critical that involvement of men be considered of equal importance as women (Hardee et al., 2016). 44However, it is noticeable that no effective, reversible and widely-available form of contraception has been developed 45 for men since the condom and as such the burden falls largely on the woman. The development of drugs that can be 46 used in the male would address a critical gap in the contraceptive portfolio. 48Progress in developing new male contraceptives has been slow for a plethora of reasons. Despite decades of research, 49 safe and effective hormonal approaches have yet to be realised and viable alternatives remain elusive (Page and Amory, 50 2018). Developing a drug for any purpose is difficult but one that blocks sperm function is a particular challenge as 72 chemical diversity libraries for novel medicinal chemistry start points. 74 Results 75Phenotypic Assay Development 76Our automated platform ( Figure 1A) allows for the identification of relatively fast-acting compounds with a rapid plate-77 processing time (~75 minutes/ 384-well plate), where the motility assay runs for ~30 minutes followed directly by the 78 AR assay (~ 45 minutes). Automated cell tracking (Figure 1B & Supplementary Figure 1A) using time-lapse images 100 the AR hits were found to be true positives (see examples in Supplementary F...