Male hormonal contraception

Practice and development of male contraception: European Academy of Andrology and American Society of Andrology guidelines

BACKGROUNDS

Despite a wide spectrum of contraceptive methods for women, the unintended pregnancy rate remains high (45% in the US), with 50% resulting in abortion. Currently, 20% of global contraceptive use is male-directed, with a wide variation among countries due to limited availability and lack of efficacy. Worldwide studies indicate that >50% of men would opt to use a reversible method, and 90% of women would rely on their partner to use a contraceptive. Additional reasons for novel male contraceptive methods to be available include the increased life expectancy, sharing the reproductive risks among partners, social issues, the lack of pharma industry involvement and the lack of opinion makers advocating for male contraception.

AIM

The present guidelines aim to review the status regarding male contraception, the current state of the art to support the clinical practice, recommend minimal requirements for new male contraceptive development and provide and grade updated, evidence-based recommendations from the European Society of Andrology (EAA) and the American Society of Andrology (ASA).

METHODS

An expert panel of academicians appointed by the EAA and the ASA generated a consensus guideline according to the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) system.

RESULTS

Sixty evidence-based and graded recommendations were produced on couple-centered communication, behaviors, barrier methods, semen analysis and contraceptive efficacy, physical agents, surgical methods, actions before initiating male contraception, hormonal methods, non-hormonal methods, vaccines, and social and ethical considerations.

CONCLUSION

As gender roles transform and gender equity is established in relationships, the male contribution to family planning must be facilitated. Efficient and safe male-directed methods must be evaluated and introduced into clinical practice, preferably reversible, either hormonal or non-hormonal. From a future perspective, identifying new hormonal combinations, suitable testicular targets, and emerging vas occlusion methods will produce novel molecules and products for male contraception.

Novel progestogenic androgens for male contraception: design, synthesis, and activity of C7 α-substituted testosterone†

Male contraceptive development has included use of testosterone (T) with or without a progestin or the use of a single molecule such as progestogenic androgens (PA) for suppression of testicular T production. Expanding upon the vast amount of data accumulated from nortestosterone (NT), NT analogs, and their prodrugs, a new series of PA, the C7 methyl, and ethyl α-substituted T analogs 7α-Methyltestosterone (7α-MT) and 7α-Ethyltestosterone (7α-ET), respectively, were hypothesized and designed to have superior androgenic and progestogenic activities when compared with parent T. Results from androgen receptor and progesterone receptor competitive binding and transcriptional activation assays showed favorable activities for these T analogs. Additionally, 7α-MT and 7α-ET were shown to be active substrates for aromatase in vitro, mitigating a potential negative impact on bone mineral density with long-term use. In conjunction with this observation, the diminished metabolism of these T analogs by 5α-reductase may reduce potential concerns for prostatic growth. In the Hershberger in vivo rat bioassay, 7α-MT and 7α-ET showed superior androgenic and anabolic activities as compared with T. These C7 α-substituted T analogs also showed clear progestogenic activity in the McPhail bioassay which evaluated endometrial glandular arborization in a rabbit model. The discovery of aromatizable molecules with reduced metabolism by 5α-reductase that have androgenic, anabolic, and progestogenic properties indicates that the core and/or prodrugs of 7α-MT and 7α-ET are promising molecules for further development as male contraceptive PAs.

HE4 overexpression in mice leads to leydig cell hyperplasia and spermatogensis impairment: Pathological implications for oligospermia

Previous studies have shown that HE4 cancer biomarker promoted cancer cell proliferation and tumor growth in mouse xenograft models. Interestingly, HE4 levels are significantly increased in the seminal plasma of oligoasthenospermia patients, raising a question on HE4 role(s) in spermatogenesis. We constructed an HE4 overexpression mouse model (HE4-OE), and observed that HE4-OE male adult mice had small testes, low sperm counts, and elevated serum/testis testosterone levels. These mice exhibited disorganized seminiferous tubules and impaired spermatogenesis. HE4 overexpression concentrated in Leydig cells, and these cells had hyperplasia and increased testosterone biosynthesis. Mechanistic studies indicated that the impaired spermatogenesis was likely caused by a local and direct action of HE4 in the testis rather than by a hypothalamus/pituitary-initiated dysregulation. The new findings reveal a novel HE4 function in male reproductive system, and suggest the existence of a subtype of primary oligoasthenospermia characterized by HE4 overexpression, Leydig cell hyperplasia, and elevated testosterone levels.

The novel BRDT inhibitor NHWD870 shows potential as a male contraceptive in mice

Small molecule inhibitors of the bromodomain and extraterminal domain (BET) family proteins have emerged as promising options not only for the treatment of multiple cancers but also for disturbing the process of sperm maturation with potential for use as viable contraceptive targets. In this study, we find that the BET family inhibitor NHWD870 and BRDT can bind well in vitro through bioinformatics software prediction and protein binding inhibition experiments. NHWD870 can produce a good contraceptive effect through animal experiments in vivo, and the fertility can be restored to normal after drug withdrawal. Transcriptomics and proteomics results suggest that NHWD870 affects pathways related to spermatogenesis and maturation, further contributing to the male infertility phenotype. Our results show that NHWD870 can induce a complete and reversible contraceptive effect in mice, which is stronger than that of JQ1 and its synthesized derivatives. This study is expected to eventually lead to clinical trials.

Daily Oral Administration of the Novel Androgen 11β-MNTDC Markedly Suppresses Serum Gonadotropins in Healthy Men

BACKGROUND

11β-methyl-19-nortestosterone (11β-MNT) is a modified testosterone (T) with androgenic and progestational activity. A single oral dose of the prodrug, 11β-MNT dodecylcarbonate (11β-MNTDC), was well tolerated in healthy men.

METHODS

We conducted a randomized, double-blind study at 2 academic medical centers. 42 healthy men (18-50 years) were randomized to receive oral placebo or 11β-MNTDC, 200 or 400 mg daily, for 28 consecutive days. Primary outcome (safety and tolerability) measures were assessed twice per week. Subjects underwent serial blood sampling over 24 hours on days 1 and 28 to assess secondary outcomes: pharmacokinetics (serum drug concentrations); pharmacodynamics of 11β-MNTDC (serum sex steroids and gonadotropins); and mood and sexual function (via validated questionnaires).

RESULTS

There were no serious adverse events. No participants discontinued because of an adverse event or laboratory test abnormality. 11β-MNTDC resulted in a dose-related increase in serum 11β-MNTDC and 11β-MNT concentrations sustained over 24 hours. Administration of 11β-MNTDC resulted in a marked suppression of serum gonadotropins, T, calculated free T, estradiol, and SHBG over the treatment period (P < 0.01). Adverse effects that may be related to 11β-MNTDC included weight gain, acne, headaches, fatigue, and mild mood changes, with 5 men reporting decreased libido and 3 decreased erectile/ejaculatory function. Serum low-density lipoprotein cholesterol, weight (~2 kg), hematocrit, and hemoglobin increased and serum high-density lipoprotein cholesterol decreased in both 11β-MNTDC groups.

CONCLUSION

Daily oral 11β-MNTDC for 28 days in healthy men markedly suppressed serum gonadotropin and T concentrations without serious adverse effects. These results warrant further evaluation of 11β-MNTDC as a potential male oral contraceptive.

Latheef S, Sharun K, Khurana SK, K. A, Tiwari R, Bhatt P, K. V, Chaicumpa W. Role of Antisperm Antibodies in Infertility, Pregnancy, and Potential forContraceptive and Antifertility Vaccine Designs: Research Progress and Pioneering Vision

Sperm of humans, non-human primates, and other mammalian subjects is considered to be antigenic. The effect of changes in autoimmunity on reproductive cells such as spermatozoa and oocytes play a critical but indistinct role in fertility. Antisperm antibodies (ASAs) are invariably present in both females and males. However, the degree of ASA occurrence may vary according to individual and gender. Although the extent of infertility due to ASAs alone is yet to be determined, it has been found in almost 9-12% of patients who are infertile due to different causes. Postcoital presence of spermatozoa in the reproductive tract of women is not a contributory factor in ASA generation. However, ASA generation may be induced by trauma to the vaginal mucosa, or by anal or oral sex resulting in the deposition of sperm inside the digestive tract. It is strongly believed that, in humans and other species, at least some antibodies may bind to sperm antigens, causing infertility. This form of infertility is termed as immunological infertility, which may be accompanied by impairment of fertility, even in individuals with normozoospermia. Researchers target ASAs for two major reasons: (i) to elucidate the association between ASAs and infertility, the reason ASAs causes infertility, and the mechanism underlying ASA-mediated infertility; and (ii) to assess the potential of ASAs as a contraceptive in humans in case ASAs influences infertility. Therefore, this review explores the potential application of ASAs in the development of anti-spermatozoa vaccines for contraceptive purposes. The usefulness of ASAs for diagnosing obstructive azoospermia, salpingitis, and oligoasthenoteratozoospermia has been reviewed extensively. Important patents pertaining to potential candidates for spermatozoa-derived vaccines that may be utilized as contraceptives are discussed in depth. Antifertility vaccines, as well as treatments for ASA-related infertility, are also highlighted. This review will address many unresolved issues regarding mechanisms involving ASAs in the diagnosis, as well as prognoses, of male infertility. More documented scientific reports are cited to support the mechanisms underlying the potential role of ASA in infertility. The usefulness of sperm antigens or ASAs (recombinant) in human and wild or captive animal contraceptive vaccines has been revealed through research but is yet to be validated via clinical testing.

Preventing secondary exposure to women from men applying a novel nestorone/testosterone contraceptive gel

BACKGROUND

Testosterone (T)/Nestorone (NES) combination gel is a potential transdermal male contraceptive that suppresses gonadotropins and spermatogenesis. Transfer of transdermal T from men to women can be prevented by washing or covering application sites with clothing.

OBJECTIVES

We hypothesized that showering or wearing a shirt over gel application sites would prevent secondary exposure of T and NES to a woman after close skin contact.

MATERIALS AND METHODS

Twelve healthy male and 12 healthy female participants were recruited. Men applied T/NES 62 mg/8 mg gel to their shoulders and upper arms. Two hours after application, female partners rubbed the application site for 15 min. Exposure in the female partner was assessed under three conditions: a shirt covered the application site; the man showered prior to skin contact; or without intervention to reduce transfer. Serum T and NES concentrations were measured by LC-MS/MS in serial blood samples for 24 h after gel exposure.

MAIN OUTCOMES

Change in female serum T and NES levels as measured by average concentration over 24 h (Cavg ).

RESULTS

Median female serum T Cavg was 23.9 ng/dL (interquartile range, 19.3, 33.9) with the shirt barrier and 26.7 ng/dL (20.7, 33.9) after showering, which was higher than baseline 20.9 ng/dL (16.7, 25.0), both p < 0.03) but lower than without intervention (58.2 ng/dL [30.9, 89.1], both p < 0.01). Female serum NES Cavg and maximum concentration were below the lower limit of quantification with the shirt barrier and after showering, but increased without intervention in six of 12 women (maximum concentration <60 pg/mL). Men had lower average serum NES levels after showering (47 pg/ml [20, 94] compared to no intervention (153.3 pg/mL [51, 241], p < 0.02).

CONCLUSION

Secondary transfer of T and NES occurs after intensive skin contact with the gel application site. Secondary transfer is decreased by a shirt barrier or showering before contact.

Effects of 28 Days of Oral Dimethandrolone Undecanoate in Healthy Men: A Prototype Male Pill

CONTEXT

Dimethandrolone (DMA) has androgenic and progestational activity. Single oral doses of DMA undecanoate (DMAU) were well tolerated and reversibly suppressed serum LH and testosterone (T) in men.

OBJECTIVE

Assess safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of oral DMAU.

DESIGN

Double-blind, randomized, placebo-controlled study.

SETTING

Two academic medical centers.

PARTICIPANTS

Healthy men (18 to 50 years).

INTERVENTIONS

One hundred men received DMAU [0, 100, 200, or 400 mg, formulated in castor oil/benzyl benzoate (C) or powder (P)] for 28 days. Subjects underwent 24-hour PK sampling on days 1 and 28 and twice weekly ambulatory visits throughout treatment.

MAIN OUTCOME MEASURES

Primary outcomes were safety and tolerability parameters (vitals, laboratory data, mood, and sexual function scores) and adverse events. Secondary outcomes were drug PK profiles and PD effects (serum LH, FSH, and sex hormones).

RESULTS

Eighty-two subjects completed the study and were included in the analysis. There were no serious adverse events. No clinically significant changes developed in safety laboratory parameters. A significant dose effect was seen for weight, hematocrit, high-density lipoprotein cholesterol, corrected QT interval, and sexual desire. Serum 24-hour average concentrations of DMAU and DMA showed dose-related increases (P < 0.001). All six subjects in the P400 group and 12 of 13 subjects in the C400 group achieved marked suppression of LH and FSH (<1.0 IU/L) and serum T (<50 ng/dL).

CONCLUSIONS

Daily oral administration of DMAU for 28 days in healthy men is well tolerated. Doses of ≥200 mg markedly suppress serum T, LH, and FSH. These results support further testing of DMAU as a male contraceptive.

Male Hormonal Contraception: Where Are We Now?

Hormonal male contraception clinical trials began in the 1970s. The method is based on the use of exogenous testosterone alone or in combination with a progestin to suppress the endogenous production of testosterone and spermatogenesis. Studies using testosterone alone showed that the method was very effective with few adverse effects. Addition of a progestin increases the rate and extent of suppression of spermatogenesis. Common adverse effects include acne, injection site pain, mood change including depression, and changes in libido that are usually mild and rarely lead to discontinuation. Current development includes long-acting injectables and transdermal gels and novel androgens that may have both androgenic and progestational activities. Surveys showed that over 50 % of men will accept a new male method and female partners will trust their partner to take oral “male pills.” Partnership between government, nongovernment agencies, academia, and industry may generate adequate interest and collaboration to develop and market the first male hormonal contraception.

Single, escalating dose pharmacokinetics, safety and food effects of a new oral androgen dimethandrolone undecanoate in man: a prototype oral male hormonal contraceptive

The novel androgen, dimethandrolone (DMA) has both androgenic and progestational activities, properties that may maximize gonadotropin suppression. We assessed the pharmacokinetics of dimethandrolone undecanoate (DMAU), an orally bioavailable, longer acting ester of DMA, for male contraceptive development. Our objective was to examine the safety and pharmacokinetics of single, escalating doses of DMAU (powder in capsule formulation) administered orally with or without food in healthy men. We conducted a randomized, double-blind Phase 1 study. For each dose of DMAU (25-800 mg), 10 male volunteers received DMAU and two received placebo at two academic medical centres. DMAU was administered both fasting and after a high-fat meal (200-800 mg doses). Serial serum samples were collected over 24 h following each dose. DMAU was well tolerated without significant effects on vital signs, safety laboratory tests or electrocardiograms. When administered while fasting, serum DMA (active compound) was detectable in only 4/10 participants after the 800 mg dose. When administered with a 50% fat meal, serum DMA was detectable in all participants given 200 mg DMAU and showed a dose-incremental increase up to 800 mg, with peak levels 4-8 h after taking the dose. Serum gonadotropins and sex hormone concentrations were significantly suppressed 12 h after DMAU administration with food at doses above 200 mg. This first-in-man study demonstrated that a single, oral dose of DMAU up to 800 mg is safe. A high-fat meal markedly improved DMAU/DMA pharmacokinetics.

Functional role of progestin and the progesterone receptor in the suppression of spermatogenesis in rodents

Synthetic progestins such as levonorgestrel (LNG) are used in combination with testosterone (T) in male contraceptive clinical trials to suppress gonadotropins secretion, but whether progestins have additional direct effects on the testis are not known. This study aimed to examine the effect of a potent progestin, (LNG), alone or in combination with testosterone (T) on spermatogenesis in adult rats, and to evaluate the functional role of the progesterone receptors (PRs) in the testis. In comparison with a low dose of LNG treatment in adult rats for 4 weeks, T and T + LNG treatment decreased testicular sperm count to 64.1 and 40.2% of control levels respectively. LNG induced germ cell apoptosis at stages I-IV and XII-XIV; T increased apoptosis at stages VII-VIII; LNG + T treatment induced greater germ cell apoptosis at a wider range of seminiferous epithelial stages. RT-PCR and Western Blots showed that PR was present in testes and up-regulated during suppression of spermatogenesis induced by testicular hormonal deprivation. PR knockout (PRKO) mice had larger testes, greater sperm production, increased numbers of Sertoli and Leydig cells. Suppression of gonadotropin and intratesticular T by GnRH-antagonist treatment induced PR promoter driven LacZ expression in Leydig cells of PRKO mice. This suggests that GnRH-antagonist treatment while inducing germ cell apoptosis also up-regulates PR. We conclude that (i) LNG + T induced greater suppression of spermatogenesis through increase in germ cell apoptosis involving a wider range of seminiferous epithelial stages than either treatment alone, (ii) up-regulation of PR was associated with inhibition of spermatogenesis, (iii) PR knockout mice showed increased sperm production suggesting that testicular PR activated events play a physiological and pharmacological inhibitory role in the testis. These data support the hypothesis that in addition to its known suppressive effects on gonadotropins, progestins may have direct inhibitory actions on the testis.

Contraceptive choices: is the future with men?

A credible, reversible male contraceptive with sufficient efficacy and convenience to rival established female methods has been eagerly awaited for some years. What are the issues surrounding its development and when is a launch likely? At present, many different approaches and targets have been identified for further development. These include spermatogenesis, unique testicular proteins, immunocontraception, the vas deferens and the potential method currently closest to fruition, hormonal contraception. This is now in Phase III studies in China and commercial studies are underway in Europe.

A new combination of testosterone and nestorone transdermal gels for male hormonal contraception

CONTEXT

Combinations of testosterone (T) and nestorone (NES; a nonandrogenic progestin) transdermal gels may suppress spermatogenesis and prove appealing to men for contraception.

OBJECTIVE

The objective of the study was to determine the effectiveness of T gel alone or combined with NES gel in suppressing spermatogenesis.

DESIGN AND SETTING

This was a randomized, double-blind, comparator clinical trial conducted at two academic medical centers.

PARTICIPANTS

Ninety-nine healthy male volunteers participated in the study.

INTERVENTIONS

Volunteers were randomized to one of three treatment groups applying daily transdermal gels (group 1: T gel 10 g+NES 0 mg/placebo gel; group 2: T gel 10 g+NES gel 8 mg; group 3: T gel 10 g+NES gel 12 mg).

MAIN OUTCOME VARIABLE

The main outcome variable of the study was the percentage of men whose sperm concentration was suppressed to 1 million/ml or less by 20-24 wk of treatment.

RESULTS

Efficacy data analyses were performed on 56 subjects who adhered to the protocol and completed at least 20 wk of treatment. The percentage of men whose sperm concentration was 1 million/ml or less was significantly higher for T+NES 8 mg (89%, P<0.0001) and T+NES 12 mg (88%, P=0.0002) compared with T+NES 0 mg group (23%). The median serum total and free T concentrations in all groups were maintained within the adult male range throughout the treatment period. Adverse effects were minimal in all groups.

CONCLUSION

A combination of daily NES+T gels suppressed sperm concentration to 1 million/ml or less in 88.5% of men, with minimal adverse effects, and may be further studied as a male transdermal hormonal contraceptive.

Complete sperm suppression induced by dienogest plus testosterone undecanoate is associated with down-regulation in the expression of upstream steroidogenic enzyme genes in rat testis

BACKGROUND

We had shown that dienogest (DNG) + testosterone undecanoate (TU) induced complete sperm suppression in rats when administered together every 45 days. On the other hand, individual drugs given alone in a similar fashion failed to achieve the same result.

STUDY DESIGN

The present study was therefore undertaken to determine the reason for such a differential sperm suppression and to correlate it with the expression of steroidogenic enzyme genes in the rat testis.

RESULTS

Administration of DNG (40 mg/kg body weight [bw]) + TU (25 mg/kg bw) every 45 days for a duration of 90 days induced spermatogenic arrest, leading to a significant reduction in testicular weight and number of precursor germ cells. Flow cytometric analysis further confirmed the same result, leading to a significant shift in the distribution of haploid cells. Measurement of testosterone (serum and intratesticular) was significantly low. Complete sperm suppression coincided with significant down-regulation in the expression of upstream steroidogenic enzyme genes represented serially by cytochrome P450 side-chain cleavage, P450 17α-hydroxylase, 3β-hydroxysteroid dehydrogenase and steroidogenic acute regulatory protein (StAR) in the testis. On the other hand, rats administered with either DNG or TU alone demonstrated incomplete sperm suppression in which the expression of all the above genes remained characteristically nonuniform.

CONCLUSION

Taken together, the above findings corroborate the fact that regulation of expression of three of the upstream steroidogenic enzymes genes and the StAR protein in rat testis is crucial in leading to complete sperm suppression as observed with DNG+TU treatment.

Male hormonal contraception: potential risks and benefits

An effective, safe, reversible, and acceptable method of contraception is an important component of reproductive health and provides the opportunity of shared responsibility for family planning for both partners. Female hormonal contraceptives have been proven to be safe, reversible, available and widely acceptable by different populations. In contrast, male hormonal contraception, despite significant progress showing contraceptive efficacy comparable to female hormonal methods during last three decades, has not yet led to an approved product. Safety of a pharmaceutical product is an appropriate concern but the majority of male hormonal contraceptive clinical trials have not reported significant short term safety concerns. While the absence of serious adverse effects is encouraging, the studies have been designed for efficacy endpoints not long term safety. In this review we summarize potential risks and benefits of putative male hormonal contraceptives on reproductive and non-reproductive organs. While the review covers what we believe will be the likely class of drugs used for male hormonal contraception a true assessment of long term risks and benefits cannot be achieved without an available product.

Does ethnicity matter in male hormonal contraceptive efficacy?

The development of male hormonal contraception has progressed significantly during the last three decades. The ultimate goal is to produce an effective, safe and reversible male method of contraception that are within reach of and can be used by all men globally. This review aims to outline the recent developments in male hormonal contraception with special emphasis on how ethnicity influences acceptability, extent of sperm suppression, and rate of recovery of spermatogenesis. Baseline differences in testicular histomorphology and testosterone metabolism between East Asian and Caucasian men have been reported, but whether this contributes significantly to varying degrees of sperm suppression in response to exogenous testosterone therapy is less known. Testosterone alone male hormonal contraceptive regimens are effective and applicable for East Asian men, and less so for Caucasians. Combinations of progestins with androgens are sufficient to optimize effectiveness of suppression and applicability to all ethnicities. New compounds such as steroidal or non-steroidal selective androgen receptor modulators with dual androgenic and progestational activities are potential compounds for further development as male hormonal contraceptive methods. At the present time, combined androgen and progestin contraceptive regimens appear to be effective, safe, reversible and convenient to use for all men with ethnic, cultural and environmental differences. Further refinements on the hormonal agent, methods of delivery, and dose optimization of the androgen relative to the progestin are necessary. This goal mandates further investment and large clinical trials in multiethnic populations to better define safety and efficacy.

Hormonal approaches to male contraception

PURPOSE OF REVIEW

Condoms and vasectomy are male-controlled family planning methods but suffer from limitations in compliance (condoms) and limited reversibility (vasectomy); thus many couples desire other options. Hormonal male contraceptive methods have undergone extensive clinical trials in healthy men and shown to be efficacious, reversible and appear to be well tolerated.

RECENT FINDINGS

The success rate of male hormonal contraception using injectable testosterone alone is high and comparable to methods for women. Addition of progestins to androgens improved the rate of suppression of spermatogenesis. Supported by government or nongovernment organizations, current studies aim to find the best combination of testosterone and progestins for effective spermatogenesis suppression and to explore other delivery methods for these hormones. Translation of these advances to widespread use in the developed world will need the manufacturing and marketing skills of the pharmaceutical industry. Availability of male contraceptives to the developing world may require commitments of governmental and nongovernmental agencies. In a time when imbalance of basic resources and population needs are obvious, this may prove to be a very wise investment.

SUMMARY

Male hormonal contraception is efficacious, reversible and well tolerated for the target population of younger men in stable relationships. Suppression of spermatogenesis is achieved with a combination of an androgen and a progestin. Partnership with industry will accelerate the marketing of a male hormonal contraceptive. Research is ongoing on selective androgen and progesterone receptor modulators that suppress spermatogenesis, minimize potential adverse events while retaining the androgenic and gonadotropin suppressive actions.

Attitudes towards the male contraceptive pill in men and women in casual and stable sexual relationships

BACKGROUND AND METHODOLOGY

Men's and women's attitudes towards the male contraceptive pill and their trust in the effective use of the male pill were investigated, as well as the associated variables of reported health behaviours, perceived self-efficacy and type of sexual relationship, using a questionnaire survey.

RESULTS

Although both sexes had a favourable attitude towards the male pill, females had a more positive attitude than men. Conversely, women had less trust that men would use the male pill effectively. Males in stable sexual relationships were more positive about the male pill than those in casual sexual relationships. Gender, relationship type and trust in the effective use of the male pill reliably predicted attitude towards the male pill. High perceived self-efficacy was related to engaging in more health behaviours, and in men a positive association between health behaviours and attitude towards the male pill has been found.

DISCUSSION AND CONCLUSIONS

A positive attitude towards the male pill does not automatically imply that the individual is confident about its effective use. Once the male pill is widely available, promotional campaigns could target not only men but also their female partners, as the latter tend to come into contact with health services more frequently. In order to increase confidence in effective implementation, a variety of presentations of the male pill should be made available in line with individual needs and lifestyles.

Combined transdermal testosterone gel and the progestin nestorone suppresses serum gonadotropins in men

CONTEXT

Testosterone (T) plus progestin combinations are the most promising hormonal male contraceptives. Nestorone (NES), a progestin without estrogenic or androgenic activity, when combined with T may be an excellent candidate for male contraception.

OBJECTIVE

Our objective was to determine the effect of transdermal NES gel alone or with T gel on gonadotropin suppression.

DESIGN AND SETTING

The randomized, unblinded clinical trial was conducted at two academic medical centers.

PARTICIPANTS

A total of 140 healthy male volunteers participated.

INTERVENTIONS

One hundred subjects were randomized initially (20 per group) to apply NES gel 2 or 4 mg, T gel 10 g, or T gel 10 g plus NES gel 2 or 4 mg daily for 20 d. Because only about half of the subjects in T plus NES 4 mg group suppressed serum gonadotropins to 0.5 IU/liter or less (suboptimal suppression), two additional groups of 20 men were randomized to apply daily T gel 10 g plus NES gel 6 or 8 mg.

MAIN OUTCOME VARIABLE

Suppression of serum LH and FSH concentrations to 0.5 IU/liter or less after treatment was the main outcome variable.

RESULTS

A total of 119 subjects were compliant with gel applications with few study-related adverse events. NES alone reduced gonadotropins significantly but less than T gel alone. Combined T gel 10g plus NES gel 6 or 8 mg suppressed both serum gonadotropins to 0.5 IU/liter or less in significantly more men than either gel alone.

CONCLUSION

Transdermal NES gel alone had gonadotropin suppression activity. Combined transdermal NES (6 or 8 mg) plus T gel demonstrated safe and effective suppression of gonadotropins, justifying a longer-term study of this combination for suppression of spermatogenesis.

Levonorgestrel enhances spermatogenesis suppression by testosterone with greater alteration in testicular gene expression in men

Prior studies have demonstrated that combined treatment of testosterone with a progestin induces a more rapid and greater suppression of spermatogenesis than testosterone treatment alone. We hypothesized that the suppressive effects of the combination of testosterone undecanoate (TU) injections plus oral levonorgestrel (LNG) on spermatogenesis may be mediated through a greater perturbation of testicular gene expression than TU alone. To test this hypothesis, we performed open testicular biopsy on 12 different adult healthy subjects: 1) four healthy men as controls; 2) four men 2 wk after TU treatment; and 3) four men 2 wk after TU + LNG administration. RNA isolated from biopsies was used for DNA microarray using the Affymetrix Human Genome U133 Plus 2.0 oligonucleotide microarrays. Gene expression with >or=2-fold changes (P < 0.05) compared with control was analyzed using the National Institutes of Health Database for Annotation, Visualization, and Integrated Discovery 2008 resource. The TU treatment altered the gene expression in 109 transcripts, whereas TU + LNG altered the gene expression in 207 transcripts compared with control. Both TU and TU + LNG administration suppressed gene expression of insulin-like 3; cytochrome P450, family 17, subfamily A1 in Leydig cells; and inhibin alpha in Sertoli cells; they increased proapoptotic transcripts BCL2-like 14, insulin-like growth factor-binding protein 3; and they decreased X-linked inhibitor of apoptosis protein. In comparison with TU treatment alone, TU + LNG treatment upregulated insulin-like 6 and relaxin 1, and downregulated RNA-binding protein transcripts. We conclude that TU + LNG administration induces more changes in testicular gene expression than TU alone. This exploratory study provided a novel and valuable database to study the mechanisms of action of hormonal regulation of spermatogenesis in men and identified testicular-specific molecules that may serve as potential targets for male contraceptive development.

Proteomic analysis of testis biopsies in men treated with injectable testosterone undecanoate alone or in combination with oral levonorgestrel as potential male contraceptive

Treatment with injectable testosterone undecanoate (TU) alone or in combination with oral levonorgestrel (LNG) resulted in marked decreases in sperm concentrations. In this study, we used proteomic analyses to examine the cellular/molecular events occurring in the human testis after TU or TU + LNG treatment. We conducted a global proteomic analysis of the human testicular biopsies before and at 2 weeks after TU alone or TU + LNG treatment. Proteins showing significant changes in expression were identified and analyzed. As a result, 17 and 46 protein spots were found with significant differential expression after the treatment with TU alone and TU + LNG, respectively. TU treatment changed the expression of heterogeneous nuclear ribonucleoprotein K (hnRNP K), proteasome inhibitor PI31 subunit (PSMF1), and superoxide dismutase [Mn] mitochondrial precursor (SOD2). These proteins inhibit "assembly", induce cell death, and promote compensatory "cell survival" in the testis. After TU + LNG treatment, "proliferation/cell survival" and "apoptosis/death" were the predominant responses in the testis. TU + LNG treatment inhibited the expression of Prolyl 4-hydroxylase beta subunit (P4HB) and Annexin A2 (Annexin II). These proteins are involved in apoptosis and cell proliferation, respectively. TU + LNG treatment also enhanced the expression of SOD2 and Parvalbumin alpha (Pvalb). These two proteins may protect testicular cells against apoptosis/death and promote cell survival. In conclusion, TU and TU + LNG treatments suppress spermatogenesis through different pathways by changing the expression of different proteins. hnRNP K, PSMF1, SOD2, P4HB, Annexin II, and Pvalb, are key proteins that may be early molecular targets responsible for spermatogenesis suppression induced by hormone treatment.

Determinants of the rate and extent of spermatogenic suppression during hormonal male contraception: an integrated analysis

CONTEXT

Male hormonal contraceptive methods require effective suppression of sperm output.

OBJECTIVE

The objective of the study was to define the covariables that influence the rate and extent of suppression of spermatogenesis to a level shown in previous World Health Organization-sponsored studies to be sufficient for contraceptive purposes (< or =1 million/ml).

DESIGN

This was an integrated analysis of all published male hormonal contraceptive studies of at least 3 months' treatment duration.

SETTING

Deidentified individual subject data were provided by investigators of 30 studies published between 1990 and 2006.

PARTICIPANTS

A total of 1756 healthy men (by physical, blood, and semen exam) aged 18-51 yr of predominantly Caucasian (two thirds) or Asian (one third) descent were studied. This represents about 85% of all the published data.

INTERVENTION(S)

Men were treated with different preparations of testosterone, with or without various progestins.

MAIN OUTCOME MEASURE

Semen analysis was the main measure.

RESULTS

Progestin coadministration increased both the rate and extent of suppression. Caucasian men suppressed sperm output faster initially but ultimately to a less complete extent than did non-Caucasians. Younger age and lower initial blood testosterone or sperm concentration were also associated with faster suppression, but the independent effect sizes for age and baseline testicular function were relatively small.

CONCLUSION

Male hormonal contraceptives can be practically applied to a wide range of men but require coadministration of an androgen with a second agent (i.e. progestin) for earlier and more complete suppression of sperm output. Whereas considerable progress has been made toward defining clinically effective combinations, further optimization of androgen-progestin treatment regimens is still required.

transient scrotal hyperthermia and levonorgestrel enhance testosterone-induced spermatogenesis suppression in men through increased germ cell apoptosis

CONTEXT

In rodents and monkeys, a combination of hormonal and physical agents accelerates germ cell death.

OBJECTIVE

A "proof of concept" study was performed to investigate whether addition of heat exposure or a progestin to an androgen induces germ cell death and more complete and rapid spermatogenesis suppression.

DESIGN AND SETTINGS

A randomized clinical trial was performed at academic medical centers.

PARTICIPANTS

We treated four groups of healthy male volunteers (18 per group) for 18 wk: 1) testosterone undecanoate (TU) 1000 mg im (first dose), followed by 500 mg im every 6 wk; 2) submersion of scrota at 43 C in water for 30 min/d for 6 consecutive days; 3) TU plus heat; and 4) TU plus oral levonorgestrel (LNG) 250 microg/d.

MAIN OUTCOME MEASURES

Semen parameters, testicular histology, and germ cell apoptosis were the main outcome measures.

RESULTS

Heat alone and TU plus heat suppressed sperm counts more than TU alone by wk 6. By wk 9, recovery began in the heat only group, whereas spermatogenesis remained suppressed in the TU plus heat group. Oral LNG plus TU suppressed spermatogenesis earlier and more severely than TU alone. At wk 2, significantly greater germ cell apoptosis occurred in heat and heat plus TU subjects, but not in subjects without heat treatment, compared with pretreatment subjects. By 9 wk, markedly smaller seminiferous tubule diameters and fewer spermatocytes and spermatids were noted in all 12 biopsies from men receiving TU, TU plus LNG, with most dramatic differences for the TU plus heat group, whereas no differences from pretreatment biopsies were observed in men who received heat treatment only.

CONCLUSIONS

Heat causes a rapid and transient suppression of spermatogenesis. TU plus heat resulted in low-sperm output that was maintained by continuous treatment with TU. Addition of an oral progestin accelerated spermatogenesis suppression by TU alone. Increased germ cell apoptosis contributed to suppression of spermatogenesis.

The quest for better contraception: future methods

With the highest rates of unintended pregnancy and abortion in the developed world, the United States has plenty of room for improving the distribution of existing contraceptive options and an imperative for developing new methods. This article surveys new and future contraceptive methods. It does not contain a comprehensive list but focuses on methods that are close to Food and Drug Administration approval or fulfill special needs across the globe.

New approaches for male fertility control: HE6 as an example of a putative target

Reversible contraceptive methods for males are still not available. During the last few years several marketing studies have clearly shown that men and women would welcome a situation where men could assume responsibility for family planning. Schering AG and Organon are currently collaborating to develop a hormonal method for male fertility control based on the combination of etonogestrel as gestagenic component and testosterone undecanoate. To further optimize male contraceptives in terms of improved efficiency, rapid onset, reversibility, fewer side effects and a convenient method of application, a search for innovative non-hormonal approaches was started. During the last few years, numerous proteins were identified which play a specific role in male fertility. These proteins have first to fulfil a set of indication-specific criteria before a drug discovery process can be initiated. The most important criteria for a putative target protein are tissue-selective expression, crucial biological function in fertility, drugable properties and feasibility of assay development for high-throughput-screening and lead optimization. The G-protein-coupled receptor HE6 was selected as target and the above selection criteria were applied. HE6 displays a preferred epididymis-specific expression pattern and belongs to the superfamily of GPCRs, which are well known to be drugable with small molecules. A knockout mouse was generated which revealed an infertility phenotype with the onset occurring 6 weeks after initiation of spermatogenesis at the latest. Surprisingly, no epididymis-specific phenotype was observed. Instead, the reabsorption of testicular fluid along the efferent ducts was strongly affected. No further obvious side effects were observed in male or female mice. This study with HE6 exemplifies how targets for male contraception have to be validated before drug development can start.

Rate, extent, and modifiers of spermatogenic recovery after hormonal male contraception: an integrated analysis

BACKGROUND

Hormonal methods for safe, reliable, and reversible contraception based on the suppression of spermatogenesis could soon become available. We have investigated the rate, extent, and predictors of reversibility of hormonal male contraception.

METHODS

We undertook an integrated multivariate time-to-event analysis of data from individual participants in 30 studies published in 1990-2005, in which sperm output was monitored every month until recovery. The primary outcome was the time for the sperm concentration to recover to a threshold of 20 million per mL, an indicator of fertility. We undertook univariate and multivariate analyses, using Kaplan-Meier and Cox's methods.

FINDINGS

1549 healthy eugonadal men who were white (n=965), Asian (almost all Chinese men; n=535), or of other origins (n=49) and aged 18-51 years underwent 1283.5 man-years of treatment and 705 man-years of post-treatment recovery. These data represented about 90% of all published data from individuals using androgen or androgen-progestagen regimens. The median times for sperm to recover to thresholds of 20, 10, and 3 million per mL were 3.4 months (95% CI 3.2-3.5), 3.0 months (2.9-3.1), and 2.5 months (2.4-2.7), respectively. Multivariate Cox's analysis showed higher rates of recovery with older age, Asian origin, shorter treatment duration, shorter-acting testosterone preparations, higher sperm concentrations at baseline, faster suppression of spermatogenesis, and lower blood concentrations of luteinising hormone at baseline. The typical probability of recovery to 20 million per mL was 67% (61-72) within 6 months, 90% (85-93) within 12 months, 96% (92-98) within 16 months, and 100% within 24 months.

INTERPRETATION

Hormonal male contraceptive regimens show full reversibility within a predictable time course. Various covariables affect the rate but not the extent of recovery, although their effect sizes are minor. These data are crucial for the further safe and practical development of such regimens.

Levonorgestrel implants enhanced the suppression of spermatogenesis by testosterone implants: comparison between Chinese and non-Chinese men

CONTEXT

Previous male contraceptive studies showed that progestins enhance spermatogenesis suppression by androgens in men.

OBJECTIVE

We compared the efficacy of spermatogenesis suppression by the combination of levonorgestrel (LNG) with testosterone (T) implants to that by T implants alone in two different ethnic groups.

DESIGN

This was a randomized trial performed in two centers with two treatment groups.

SETTINGS

The study was performed at the Academic Medical Center in the United States and the Research Institute in China.

PARTICIPANTS

Forty non-Chinese and 40 Chinese healthy male volunteers were studied.

INTERVENTIONS

Subjects were randomized to receive four LNG implants together with four T implants (inserted on d 1 and wk 15-18) vs. T implants alone for 30 wk.

MAIN OUTCOME MEASURES

The primary end point compared the efficiency of suppression to severe oligozoospermia (1 x 10(6)/ml) by LNG plus T implants vs. that by T implants alone. The secondary end point examined differences in spermatogenesis suppression between Chinese and non-Chinese subjects.

RESULTS

LNG plus T implants caused more suppression of spermatogenesis to severe oligozoospermia during the treatment period than T implants alone at both sites (P < 0.02). In Chinese men, severe oligozoospermia was achieved in more than 90% of the men in both treatment groups. Suppression to severe oligozoospermia was less in the non-Chinese men (59%) after T alone (P < 0.020); this difference disappeared with combined treatment (89%). T implant extrusion occurred in six men. Acne and increased hemoglobin were the most common adverse events.

CONCLUSION

T implants resulted in more pronounced spermatogenesis suppression in Chinese men. Addition of LNG implants to T implants enhanced the suppression of spermatogenesis in the treatment period in both Chinese and non-Chinese men.

A multicentre study investigating subcutaneous etonogestrel implants with injectable testosterone decanoate as a potential long-acting male contraceptive

BACKGROUND

The combination of etonogestrel implants with injectable testosterone decanoate was investigated as a potential male contraceptive.

METHODS

One hundred and thirty subjects were randomly assigned to three treatment groups, all receiving two etonogestrel rods (204 mg etonogestrel) and 400 mg testosterone decanoate either every 4 weeks (group I, n = 42), or every 6 weeks (group II, n = 51) or 600 mg testosterone decanoate every 6 weeks (group III, n = 37) for a treatment period of 48 weeks.

RESULTS

One hundred and ten men completed 48 weeks of treatment. Sperm concentrations of <1 x 10(6)/ml were achieved in 90% (group I), 82% (group II) and 89% (group III) of subjects by week 24. Suppression was slower in group II, which also demonstrated more frequent escape from gonadotrophin suppression than groups I and III. Peak testosterone concentrations remained in the normal range throughout in all groups. Mean trough testosterone concentrations were initially subphysiological but increased into the normal range during treatment. Mean haemoglobin levels increased in group I, and a non-significant increase in weight and decline in high-density lipoprotein cholesterol was observed in all groups. Fourteen subjects discontinued treatment due to adverse events.

CONCLUSIONS

Subcutaneous etonogestrel implants in combination with injectable testosterone decanoate resulted in profound suppression of spermatogenesis that could be maintained for up to 1 year. Efficacy of suppression was less in group II, probably due to inadequate testosterone dosage. This combination has potential as a long-acting male hormonal contraceptive.

Discovery and therapeutic promise of selective androgen receptor modulators

Androgens are essential for male development and the maintenance of male secondary characteristics, such as bone mass, muscle mass, body composition, and spermatogenesis. The main disadvantages of steroidal androgens are their undesirable physicochemical and pharmacokinetic properties. The recent discovery of nonsteroidal selective androgen receptor modulators (SARMs) provides a promising alternative for testosterone replacement therapies with advantages including oral bioavailability, flexibility of structural modification, androgen receptor specificity, tissue selectivity, and the lack of steroid-related side effects.

Expression of human hormone-sensitive lipase (HSL) in postmeiotic germ cells confers normal fertility to HSL-deficient mice

Hormone-sensitive lipase (HSL, Lipe, E.C.3.1.1.3) is a multifunctional fatty acyl esterase that is essential for male fertility and spermatogenesis and that also plays important roles in the function of adipocytes, pancreatic beta-cells, and adrenal cortical cells. Gene-targeted HSL-deficient (HSL-/-) male mice are infertile, have a 2-fold reduction in testicular mass, a 2-fold elevation of the ratio of esterified to free cholesterol in testis, and unique morphological abnormalities in round and elongating spermatids. Postmeiotic germ cells in the testis express a specific HSL isoform. We created transgenic mice expressing a normal human testicular HSL cDNA from the mouse protamine-1 promoter, which mediates expression specifically in postmeiotic germ cells. Testicular cholesteryl esterase activity was undetectable in HSL-/- mice, but in HSL-/- males expressing the testicular transgene, activity was 2-fold greater than normal. HSL transgene mRNA became detectable in testes between 19 and 25 days of age, coinciding with the first wave of postmeiotic transcription in round spermatids. In contrast to nontransgenic HSL-/- mice, HSL-/- males expressing the testicular transgene were normal with respect to fertility, testicular mass, testicular esterified/free cholesterol ratio, and testicular histology. Their cauda epididymides contained abundant, normal-appearing spermatozoa. We conclude that human testicular HSL is functional in mouse testis and that the mechanism of infertility in HSL-deficient males is cell autonomous and resides in postmeiotic germ cells, because HSL expression in these cells is in itself sufficient to restore normal fertility.