Repros Therapeutics, Inc.

To determine the effect of enclomiphene citrate in men with secondary hypogonadism.

Phase II clinical trial.

Community dwelling men making visits to physician offices.

Men with secondary hypogonadism.

Oral administration of enclomiphene citrate or 1% topical T gel.

Luteinizing hormone, FSH, T, and semen analysis.

Treatment with enclomiphene citrate resulted in increased morning serum T, E2, and LH levels similar to those obtained with a topical T gel in men with secondary hypogonadism. Follicle-stimulating hormone and LH were increased with enclomiphene, and sperm counts were conserved.

Enclomiphene citrate reverses the two hallmarks of secondary hypogonadism, namely, low serum total T and low or inappropriately normal LH while preserving sperm production.

NCT01270841 (ClinicalTrials.gov Identifier NCT01270841).

Immunization of female mammals with native zona pellucida (ZP) proteins is known to cause infertility. Since each human ZP protein is now available as a purified recombinant protein, is it possible to compare the immunocontraceptive potential of each ZP protein. A breeding study was conducted in cynomolgus monkeys (Macaca fasicularis) after immunization with recombinant human ZP (rhZP) proteins (ZPA, ZPB, ZPC) separately and in combinations. This study demonstrated that immunization with recombinant human ZPB (rhZPB) protein caused cynomolgus monkeys to become infertile for 9-35 months. A second study was conducted in baboons (Papio cynocephalus), which yielded a similar result. The baboons immunized with rhZPB became infertile for 9 to > 20 months. During the time of maximum antibody titre, some animals experienced disruption of the menstrual cycle, but eventually all of the animals resumed normal menstrual cycles. Control animals and animals immunized with other rhZP proteins all became pregnant before any of the rhZPB-treated animals. This is the first study in which a recombinant ZP protein has consistently induced infertility in a primate without permanent disruption of the normal menstrual cycle.

The zona pellucida (ZP) is an extracellular matrix composed of multiple glycoproteins that surrounds all mammalian oocytes. Analysis of the genes encoding the ZP proteins indicates that there are three classes ZPA (largest), ZPB (intermediate) and ZPC (smallest). Polyclonal antibodies developed against recombinant proteins of human and pig ZP have been used to identify immunohistochemically the components of the ZP of cynomolgus monkeys during the course of follicular development. Digoxigenin-labelled cDNA probes specific for the mRNA encoding ZPA, ZPB or ZPC were used to probe sections of cynomolgus monkey ovaries by in situ hybridization. mRNA encoding ZPA was identified in growing follicles at all stages and was seen in the granulosa cells of mature preovulatory follicles. ZPB protein and mRNA encoding ZPB were present in oocytes in secondary follicles and to a lesser extent in tertiary follicles, but were not found in primordial, primary or antral follicles or granulosa cells. ZPC protein and mRNA encoding ZPC were present in oocytes at all stages of folliculogenesis. These results suggest that each component of the ZP is produced and secreted at specific stages of folliculogenesis and that granulosa cells may be contributing to the synthesis of ZPA and ZPC.