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

Testosterone and male contraception

PURPOSE OF REVIEW

Rates of unintended pregnancy have remained relatively stagnant for many years, despite a broad array of female contraceptive options. Recent restrictions on access to abortion in some countries have increased the urgency for expanding contraceptive options. Increasing data suggest men are keen to utilize novel reversible male contraceptives.

RECENT FINDINGS

Despite decades of clinical research in male contraception, no reversible hormonal product currently exists. Nestorone/testosterone, among other novel androgens, shows promise to finally move to pivotal Phase 3 studies and introduction to the marketplace.

SUMMARY

Hormonal male contraception utilizes androgens or androgen-progestin combinations to exploit negative feedback that regulates the hypothalamic-pituitary-testicular axis. By suppressing release of gonadotropins, these agents markedly decrease endogenous testosterone production, lower intratesticular testosterone and suppress spermatogenesis. The addition of a progestin enhances the degree and speed of sperm suppression. The androgen component preserves a state of symptomatic eugonadism in the male. There is growing demand and acceptance of male contraceptive options in various forms. As these formulations progress through stages of drug development, regulatory oversight and communication with developers around safety and efficacy standards and garnering industry support for advancing the production of male contraceptives will be imperative.

Regulatory challenges of new male contraceptive methods

INTRODUCTION

Progress in male contraception development faces the challenge of a lack of regulatory precedent and guidelines on the evidence (trial design and primary endpoint) required for marketing approval. Moreover, the development of a male contraceptive is complicated by the fact that the clinical treatment effect; prevention of pregnancy, is not measured in the patient receiving the intervention.

DISCUSSION

Regulatory precedent and guidelines exist for female hormonal contraceptives but their applicability to male contraceptive products likely varies based on the mode of action and the anticipated pharmacodynamic effects of the product. The unique attributes of male contraceptives, including the frequent delay between the intervention (e.g., vasectomy and hormonal methods) and ultimate contraceptive effect, sperm suppression near azoospermia, and pregnancy prevention need to be addressed.

CONCLUSION

This article describes the regulatory challenges faced by developers of male contraceptive products and offers proposals, paving the way for the development of both hormonal methods and non-hormonal approaches. Our article intends to suggest the directions but cannot substitute for the advice of regulatory agencies.

Initiating male contraception methods

Non-surgical (reversible) male contraception methods, when approved for general clinical application, should be made available to all interested men aged 18 50 years in good general health regardless of their semen parameters. In the preliminary workup, a complete personal and family history aimed at identifying specific conditions that may potentially increase the risks for adverse effects (associated with testosterone replacement) is advisable but a general or andrological examination is not required, unless indicated by the history. Baseline body weight, blood pressure and haemoglobin should be recorded for the purpose of future monitoring. While risks and benefits of vasectomy have been well established, appropriately nuanced patient counselling and assessment are essential for ensuring a satisfactory outcome of vasectomy.

Male animal sterilization: history, current practices, and potential methods for replacing castration

Sterilization and castration have been synonyms for thousands of years. Making an animal sterile meant to render them incapable of producing offspring. Castration or the physical removal of the testes was discovered to be the most simple but reliable method for managing reproduction and sexual behavior in the male. Today, there continues to be global utilization of castration in domestic animals. More than six hundred million pigs are castrated every year, and surgical removal of testes in dogs and cats is a routine practice in veterinary medicine. However, modern biological research has extended the meaning of sterilization to include methods that spare testis removal and involve a variety of options, from chemical castration and immunocastration to various methods of vasectomy. This review begins with the history of sterilization, showing a direct link between its practice in man and animals. Then, it traces the evolution of concepts for inducing sterility, where research has overlapped with basic studies of reproductive hormones and the discovery of testicular toxicants, some of which serve as sterilizing agents in rodent pests. Finally, the most recent efforts to use the immune system and gene editing to block hormonal stimulation of testis function are discussed. As we respond to the crisis of animal overpopulation and strive for better animal welfare, these novel methods provide optimism for replacing surgical castration in some species.

Hormone Regulation in Testicular Development and Function

The testes serve as the primary source of androgens and the site of spermatogenesis, with their development and function governed by hormonal actions via endocrine and paracrine pathways. Male fertility hinges on the availability of testosterone, a cornerstone of spermatogenesis, while follicle-stimulating hormone (FSH) signaling is indispensable for the proliferation, differentiation, and proper functioning of Sertoli and germ cells. This review covers the research on how androgens, FSH, and other hormones support processes crucial for male fertility in the testis and reproductive tract. These hormones are regulated by the hypothalamic-pituitary-gonad (HPG) axis, which is either quiescent or activated at different stages of the life course, and the regulation of the axis is crucial for the development and normal function of the male reproductive system. Hormonal imbalances, whether due to genetic predispositions or environmental influences, leading to hypogonadism or hypergonadism, can precipitate reproductive disorders. Investigating the regulatory network and molecular mechanisms involved in testicular development and spermatogenesis is instrumental in developing new therapeutic methods, drugs, and male hormonal contraceptives.

Nestorone (segesterone acetate) effects on neuroregeneration

Nestorone® (segesterone acetate) is a progestin with a chemical structure closely related to progesterone with high affinity and selectivity for the progesterone receptor without significant interaction with other steroid receptors. It has been developed for female and male contraception and is FDA-approved in a first long-acting contraceptive vaginal system for female contraception. Its safety has been extensively demonstrated in both preclinical and clinical studies for contraceptive indications. Nestorone was found to display neuroprotective and neuroregenerative activity in animal models of various central nervous system diseases, including multiple sclerosis, stroke, and amyotrophic lateral sclerosis. Reviewed herein are neuroprotective and myelin- regenerating properties of Nestorone in various animal models and its translational potential as a therapeutic agent for debilitating neurological diseases for which limited therapeutic options are available (Table 1).

Male contraception: narrative review of ongoing research

BACKGROUND

Since the release of the combined oral contraceptive pill in 1960, women have shouldered the burden of contraception and family planning. Over 60 years later, this is still the case as the only practical, effective contraceptive options available to men are condoms and vasectomy. However, there are now a variety of promising hormonal and non-hormonal male contraceptive options being studied. The purpose of this narrative review is to provide clinicians and laypeople with focused, up-to-date descriptions of novel strategies and targets for male contraception. We include a cautiously optimistic discussion of benefits and potential drawbacks, highlighting several methods in preclinical and clinical stages of development.

RESULTS

As of June 2023, two hormonal male contraceptive methods are undergoing phase II clinical trials for safety and efficacy. A large-scale, international phase IIb trial investigating efficacy of transdermal segesterone acetate (Nestorone) plus testosterone gel has enrolled over 460 couples with completion estimated for late 2024. A second hormonal method, dimethandrolone undecanoate, is in two clinical trials focusing on safety, pharmacodynamics, suppression of spermatogenesis and hormones; the first of these two is estimated for completion in December 2024. There are also several non-hormonal methods with strong potential in preclinical stages of development.

CONCLUSIONS

There exist several hurdles to novel male contraception. Therapeutic development takes decades of time, meticulous work, and financial investment, but with so many strong candidates it is our hope that there will soon be several safe, effective, and reversible contraceptive options available to male patients.

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.

Design of an international male contraceptive efficacy trial using a self-administered daily transdermal gel containing testosterone and segesterone acetate (Nestorone)

Injectable male hormonal contraceptives are effective for preventing pregnancy in clinical trials; however, users may prefer to avoid medical appointments and injections. A self-administered transdermal contraceptive gel may be more acceptable for long-term contraception. Transdermal testosterone gels are widely used to treat hypogonadism and transdermal administration may have utility for male contraception; however, no efficacy data from transdermal male hormonal contraceptive gel are available. We designed and are currently conducting an international, multicenter, open-label study of self-administration of a daily combined testosterone and segesterone acetate (Nestorone) gel for male contraception. The transdermal approach to male contraception raises novel considerations regarding adherence with the daily gel, as well as concern about the potential transfer of the gel and the contraceptive hormones to the female partner. Enrolled couples are in committed relationships. Male partners have baseline normal spermatogenesis and are in good health; female partners are regularly menstruating and at risk for unintended pregnancy. The study's primary outcome is the rate of pregnancy in couples during the study's 52-week efficacy phase. Secondary endpoints include the proportion of male participants suppressing sperm production and entering the efficacy phase, side effects, hormone concentrations in male participants and their female partners, sexual function, and regimen acceptability. Enrollment concluded on November 1, 2022, with 462 couples and enrollment is now closed. This report outlines the strategy and design of the first study to examine the contraceptive efficacy of a self-administered male hormonal contraceptive gel. The results will be presented in future reports. IMPLICATIONS: The development of a safe, effective, reversible male contraceptive would improve contraceptive options and may decrease rates of unintended pregnancy. This manuscript outlines the study design and analysis plan for an ongoing large international trial of a novel transdermal hormone gel for male contraception. Successful completion of this and future studies of this formulation may lead to the approval of a male contraceptive.

Male contraception development: monitoring effective spermatogenesis suppression utilizing a user-controlled sperm concentration test compared with standard semen analysis

OBJECTIVE

To determine whether a user-controlled sperm concentration test compared with standard semen analysis can effectively monitor spermatogenesis suppression for male contraception.

DESIGN

Single center, prospective sub study of the ongoing clinical trial: "Study of daily application of Nestorone and testosterone combination gel for male contraception."

SETTING

Research institute at an academic medical center.

PARTICIPANT(S)

Couples participating in the male contraceptive clinical trial.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE(S)

The ability by participants to monitor sperm suppression to a threshold compatible with contraceptive efficacy utilizing a user-controlled test verified by sperm concentration determined by standard laboratory methods.

RESULT(S)

Thirty-eight men participating in a hormonal male contraceptive clinical trial provided multiple samples during spermatogenesis suppression for this substudy. Participants, employing a user-controlled test, correctly identified the absence of sperm (a negative test) in 100% of their laboratory-confirmed azoospermic samples (n = 122). Participants also identified 100% of samples (n = 73) with sperm >0.2 million/mL as positive. Sperm counts between 0.01 and 0.2 million/mL were identified as negative in 96% of samples. Trial participants noted the overall ease of using the test with respect to sample preparation, test timing, and result interpretation, and that they could accurately use this test at home without difficulty.

CONCLUSION(S)

Participants undergoing spermatogenesis suppression in a hormonal male contraceptive trial performed user-controlled test to determine whether their semen sperm concentration was ≤ or >0.2 million/mL. Compared with standard semen analyses, participants correctly identified 100% of samples with sperm counts >0.2 million/mL as positive (Sensitivity 100%). A positive result when the couple is using a male contraceptive method triggers the need for semen analysis by a laboratory while the couple uses another method of contraception. Participants correctly diagnosed samples ≤0.2 million sperm/mL as negative in 99% of samples (specificity 99%). A negative result indicates a sperm concentration ≤0.2 million/mL, well below the threshold of ≤1 million/mL offering contraceptive efficacy demonstrated by prior studies. At-home sperm concentration test would minimize the need for users to return to the clinic to monitor suppression of spermatogenesis, decreasing cost and burden of male contraception trials and increasing practicality of the method.

CLINICAL TRIAL REGISTRATION NUMBER

NCT: 03452111.

Emerging concepts in male contraception: a narrative review of novel, hormonal and non-hormonal options

Access to reliable contraception is a pillar of modern society. The burden of unintended pregnancy has fallen disproportionately on the mother throughout human history; however, recent legal developments surrounding abortion have sparked a renewed interest in male factor contraceptives beyond surgical sterilization and condoms. Modern efforts to develop reversible male birth control date back nearly a century and initially focused on altering the hypothalamic-pituitary-testes axis. These hormonal contraceptives faced multiple barriers, including systemic side effects, challenging dosing regimens, unfavorable routes of delivery, and the public stigma surrounding steroid use. Novel hormonal agents are seeking to overcome these barriers by limiting the side effects and simplifying use. Non-hormonal contraceptives are agents that target various stages of spermatogenesis; such as inhibitors of retinoic acid, Sertoli cell-germ cell interactions, sperm ion channels, and other small molecular targets. The identification of reproductive tract-specific genes associated with male infertility has led to more targeted drug development, made possible by advances in CRISPR and proteolysis targeting chimeras (PROTACs). Despite multiple human trials, no male birth control agents have garnered regulatory approval in the United States or abroad. This narrative review examines current and emerging male contraceptives, including hormonal and non-hormonal agents.

Male contraception is coming: Who do men want to prescribe their birth control?

OBJECTIVE

To assess men's preferences for healthcare provider from whom they would obtain hormonal male contraceptive (HMC) methods.

STUDY DESIGN

We asked participants from 3 clinical trials of investigational HMC methods-an oral pill (11β-Methyl-19-nortestosterone-17β-dodecylcarbonate, 11β-MNTDC), intramuscular or subcutaneous injection (Dimethandrolone undecanoate), and transdermal gel (Nestorone and testosterone)-to rank their top 3 preferred HMC providers from a list including: men's health doctor (urologist/andrologist), hormonal doctor (endocrinologist), reproductive health doctor (OB/GYN), family planning clinician (community health worker, midwife, nurse practitioner), regular doctor (family medicine/internal medicine), and community pharmacist. We examined preferences based on their rankings and conducted bivariate analyses. Collapsing the various specialists (men's health doctor, hormonal doctor, reproductive health doctor, and family planning clinician) into a single provider type, we examined participant demographics against provider preference (regular doctor, pharmacist, or specialist).

RESULTS

Participants across the 3 trials (n = 124) ranked their regular doctor (44%) and community pharmacist (18%) as their most preferred HMC provider; these preferences did not differ significantly by trial and drug formulation. Specialists in family planning (13%), men's health (12%), reproductive health (10%), and hormones (4%) were least frequently ranked as their preferred provider. Older and higher educated participants more often preferred specialists over regular doctors and pharmacists (p = 0.02 and p = 0.01).

CONCLUSIONS

Despite receiving contraceptive steroid hormones and care from endocrinologists and family planning specialists in a clinical trial, participants would prefer to obtain contraception from their regular doctor.

IMPLICATIONS

As most men expect to obtain hormonal male contraceptives from their regular doctor when commercially available, primary care physicians should become familiar with HMCs and be prepared to provide counseling and options accordingly.

Androgens in male contraception

Rates of unplanned pregnancies are high globally, burdening women and families. Efforts to develop male contraceptive agents have been thwarted by unacceptable failure rates, side effects and a dearth of pharmaceutical industry involvement. Hormonal male contraception consists of exogenous androgens which exert negative feedback on the hypothalamic-pituitary-gonadal axis and suppress gonadotropin production. This in turn suppresses testicular testosterone production and sperm maturation. Addition of a progestin suppresses spermatogenesis more effectively in men. Contraceptive efficacy studies in couples have shown male hormonal methods are effective and reversible, but also may come with side effects related to sexual desire, acne and serum cholesterol and inconvenient methods of dosing and delivery. Recently, novel androgens as potential contraceptive agents are being evaluated in early clinical trials and look to overcome these drawbacks. Here we summarize landmark studies of prototype male hormonal contraceptives, showcasing recent advances and future prospects in this important area of public health.

Hormonal Male Contraception: Getting to Market

Rates of unplanned pregnancies are high and stagnant globally, burdening women, families and the environment. Local limitations placed upon contraceptive access and abortion services exacerbate global disparities for women. Despite survey data suggesting men and their partners are eager for expanded male contraceptive options, efforts to develop such agents have been stymied by a paucity of monetary investment. Modern male hormonal contraception, like female hormonal methods, relies upon exogenous progestins to suppress the hypothalamic-pituitary-gonadal axis, in turn suppressing testicular testosterone production and sperm maturation. Addition of an androgen augments gonadotropin suppression, more effectively suppressing spermatogenesis in men, and provides androgenic support for male physiology. Previous contraceptive efficacy studies in couples have shown that hormonal male methods are effective and reversible. Recent efforts have been directed at addressing potential user and regulatory concerns by utilizing novel steroids and varied routes of hormone delivery. Provision of effective contraceptive options for men and women is an urgent public health need. Recognizing and addressing the gaps in our contraceptive options and engaging men in family planning will help reduce rates of unplanned pregnancies in the coming decades.

Contraceptive drug, Nestorone, enhances stem cell-mediated remodeling of the stroke brain by dampening inflammation and rescuing mitochondria

Ischemic stroke remains a significant unmet need causing massive mortality and morbidity due to few treatment options with limited therapeutic window. The progestin Nestorone® (segesterone acetate) displays high affinity for the progesterone receptor in exerting its potent birth control and hormone replacement therapy. Accumulating evidence implicates a new utility of Nestorone in affording neuroprotection in a variety of central nervous system diseases, including stroke. However, the mechanism of action mediating Nestorone's neuroprotection in stroke remains unknown. Here, we showed that stand-alone treatments of Nestorone or human amniotic fluid-derived stem cells (hAFSc), but more pronounced with their combined treatment, led to significant improvements in behavioral function and reductions in infarction and peri-infarct cell loss in adult rats with ischemic stroke. We detected significantly lower levels of pro-inflammatory signals (OX6 and IBA1) coupled with enhanced levels of stem cell proliferation (Ki67) and differentiation (DCX and MAP2) in both brain and spleen of stroke rats that received stand-alone or combined treatments of Nestorone and hAFSc. In concert, the in vitro oxygen-glucose deprivation stroke model revealed that neural stem cells treated with Nestorone exhibited increased stem cell proliferation and differentiation that was accompanied by rescue of the mitochondrial respiratory activity characterized by reduced mitochondrial reactive oxygen species, increased ATP, elevated mitochondrial deacetylase Sirtuin 3 (SIRT3), and a normalized ratio of acetyl-superoxide dismutase 2 (Ac-SOD2)/SOD2, suggesting the key role of mitochondrial metabolism and oxidative protection in Nestorone's therapeutic effects in stroke.

[New frontiers in contraception research]

Improving current contraceptives and discover novel methods easy to use with added health benefits would meet the needs of couples who seek alternatives to current methods. New delivery systems target user-controlled, longer-acting options to provide choice, user's autonomy and improve compliance. Self-injections, microarray patches, pod rings able to deliver several molecules aim to prevent both pregnancies and sexually transmitted infections. Improved intrauterine systems and non-surgical permanent methods are also on the research agenda. The search for novel methods must continue, to curb maternal mortality led by multiple pregnancies and unsafe abortion, still a burden in many countries.

Update on Novel Hormonal and Nonhormonal Male Contraceptive Development

BACKGROUND

The advent of new methods of male contraception would increase contraceptive options for men and women and advance male contraceptive agency. Pharmaceutical R&D for male contraception has been dormant since the 1990s. The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) has supported a contraceptive development program since 1969 and supports most ongoing hormonal male contraceptive development. Nonhormonal methods are in earlier stages of development.

CONTENT

Several hormonal male contraceptive agents have entered clinical trials. Novel single agent products being evaluated include dimethandrolone undecanoate, 11β-methyl-nortestosterone dodecylcarbonate, and 7α-methyl-19-nortestosterone. A contraceptive efficacy trial of Nestorone®/testosterone gel is underway. Potential nonhormonal methods are at preclinical stages of development. Many nonhormonal male contraceptive targets that affect sperm production, sperm function, or sperm transport have been identified.

SUMMARY

NICHD supports development of reversible male contraceptive agents. Other organizations such as the World Health Organization, the Population Council, and the Male Contraception Initiative are pursuing male contraceptive development, but industry involvement remains limited.

Emerging approaches to male contraception

Despite significant interests in contraception by men, effective methods of male contraception are limited to vasectomy and condoms. Recently, there have been several promising advances in male contraceptive research. This review will update readers on recent research in both hormonal and nonhormonal approaches to male contraception. Hormonal approaches to male contraception have been stymied by adverse effects, formulations requiring injections or implants, a 5% to10% nonresponse rate, as well as poor understanding of user acceptability. In the last several years, research has focused on novel, orally bioavailable androgens such as dimethandrolone undecanoate and 11β-methyl-19-nor-testosterone. Additionally, combinations of a topical testosterone gel combined with a gel containing segesterone acetate, a potent progestin, have shown promise in clinical trials recently. Simultaneously, significant preclinical progress has been made in several approaches to nonhormonal male contraceptives, including compounds that inhibit sperm motility such as eppin, compounds that inhibit retinoic acid binding or biosynthesis, and reversible approaches to obstruction of the vas deferens. It is imperative for these areas of research to continue making strides so that there is a gamut of contraceptive options for couples to choose from. Some of these approaches will hopefully reach clinical utility soon, greatly improving contraceptive choice for couples.

Progress in progestin-based therapies for neurological disorders

Hormone therapy, primarily progesterone and progestins, for central nervous system (CNS) disorders represents an emerging field of regenerative medicine. Following a failed clinical trial of progesterone for traumatic brain injury treatment, attention has shifted to the progestin Nestorone for its ability to potently and selectively transactivate progesterone receptors at relatively low doses, resulting in robust neurogenetic, remyelinating, and anti-inflammatory effects. That CNS disorders, including multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), spinal cord injury (SCI), and stroke, develop via demyelinating, cell death, and/or inflammatory pathological pathways advances Nestorone as an auspicious candidate for these disorders. Here, we assess the scientific and clinical progress over decades of research into progesterone, progestins, and Nestorone as neuroprotective agents in MS, ALS, SCI, and stroke. We also offer recommendations for optimizing timing, dosage, and route of the drug regimen, and identifying candidate patient populations, in advancing Nestorone to the clinic.

Male Contraception

Unintended pregnancy is a global public health problem. Despite a variety of female contraceptive options, male contraceptive options are limited to the condom and vasectomy. Condoms have high failure rates and surgical vasectomy is not reliably reversible. There is a global need and desire for novel male contraceptive methods. Hormonal methods have progressed the furthest in clinical development and androgen plus progestin formulations hold promise as a marketable, reversible male contraceptive over the next decade. Investigators have tested androgen plus progestin approaches using oral, transdermal, subdermal, and injectable drug formulations and demonstrated the short-term safety and reversibility of hormonal male contraception. The most commonly reported side effects associated with hormonal male contraception include weight gain, acne, slight suppression of serum high-density cholesterol, mood changes, and changes in libido. Efficacy trials of hormonal male contraceptives have demonstrated contraceptive efficacy rates greater than that of condoms. Although there has been less progression in the development of nonhormonal male contraceptives, potentially reversible vaso-occlusive methods are currently in clinical trials in some countries. Various studies have confirmed both men and women's desire for novel male contraceptives. Barriers to development include an absence of investment from pharmaceutical companies, concerns regarding side effects and spermatogenic rebound with hormonal methods, and lack of clear reversibility and proven effectiveness of nonhormonal methods. The ultimate availability of male contraceptives could have an important impact on decreasing global unintended pregnancy rates (currently 40% of all pregnancies) and will be a step towards reproductive justice and greater equity in family planning.

Advances in contraception research and development

PURPOSE OF REVIEW

In the past few years, there have been great advances in contraceptive technology and development. Here we review advances in contraception over the past two years including new medications, and technologies.

RECENT FINDINGS

Contraception must be discussed within the context of individual goals and context. New contraceptive options approved by the FDA in the past two years include a year-long vaginal ring, a progestin-only pill that is as effective as combined oral contraceptive pills, a new hormonal patch and a vaginal gel that may also help prevent sexually transmitted infections.There are still areas of contraceptive research that are very much unknown including biomarkers of contraceptive efficacy or side effects, how individuals or groups metabolize contraception, initiation around reproductive life events or the discontinuation of other methods.

SUMMARY

There have been many new contraceptives developed over the past few years to address challenges of existing contraception and create new methods; yet, there remain many unanswered questions in contraceptive research. Contraceptive technology has far-reaching consequences, and independent of technology itself, represents a great opportunity for truly personalized medicine.

Effectiveness of testosterone therapy in hypogonadal patients and its controversial adverse impact on the cardiovascular system

Testosterone is the major male hormone produced by testicles which are directly associated with man's appearance and secondary sexual developments. Androgen deficiency starts when the male hormonal level falls from its normal range though, in youngsters, the deficiency occurs due to disruption of the normal functioning of pituitary, hypothalamus glands, and testes. Thus, testosterone replacement therapy was already known for the treatment of androgen deficiency with lesser risks of producing cardiovascular problems. Since from previous years, the treatment threshold in the form of testosterone replacement therapy has effectively increased to that extent that it was prescribed for those conditions which it was considered as inappropriate. However, there are some research studies and clinical trials available that proposed the higher risk of inducing cardiovascular disease with the use of testosterone replacement therapy. Thus under the light of these results, the FDA has published the report of the increased risk of cardiovascular disease with the increased use of testosterone replacement therapy. Nevertheless, there is not a single trial available or designed that could evaluate the risk of cardiovascular events with the use of testosterone replacement therapy. As a result, the use of testosterone still questioned the cardiovascular safety of this replacement therapy. Thus, this literature outlines the distribution pattern of disease by investigating the data and link between serum testosterone level and the cardiovascular disease, also the prescription data of testosterone replacement therapy patients and their tendency of inducing cardiovascular disease, meta-analysis and the trials regarding testosterone replacement therapy and its connection with the risks of causing cardiovascular disease and lastly, the possible effects of testosterone replacement therapy on the cardiovascular system. This study aims to evaluate the available evidence regarding the use of testosterone replacement therapy when choosing it as a treatment plan for their patients.

Continuing the search for a hormonal male contraceptive

This chapter discusses the mechanisms of action of hormonal male contraception, which suppresses the hypothalamic-pituitary-testis axis. When the intratesticular concentration of testosterone is subsequently suppressed to adequately low concentrations, spermatogenesis is arrested. Androgens are a necessary hormonal male contraceptive component because they not only suppress the hypothalamic-pituitary-testis axis, but also provide the male hormone necessary to maintain peripheral androgen functions. Past studies using testosterone alone and testosterone combined with progestins demonstrated contraceptive efficacy in the female partner at rates similar to combined hormonal female methods. Newer hormonal male contraceptive formulations and the alternative routes of administration are discussed, along with potential barriers, challenges, and opportunities for hormonal male contraceptive development. Novel methods that are safe, effective, reversible, user-friendly, and coitus-independent are intrinsic to equitably meet the various needs and limitations of an increasingly diverse population.

Development of Novel Male Contraceptives

Unintended pregnancy is surprisingly common, accounting for 40-50% of pregnancies worldwide. Contraception is the most effective means of preventing unintended pregnancy. Seventy percent of all contraceptives are used by women; however, some women are unable to use contraceptives due to health conditions or side effects. Many men wish to take a more active role family planning, but currently have only two effective male contraceptive options, condoms and vasectomy. Therefore, work to develop novel male contraceptives analogous to popular female methods, such as daily pills or long-acting shots and implants, is underway. This paper will briefly discuss the pros and cons of condoms and vasectomies, and then review the research into novel methods of male contraception.

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.

Toward Development of the Male Pill: A Decade of Potential Non-hormonal Contraceptive Targets

With the continued steep rise of the global human population, and the paucity of safe and practical contraceptive options available to men, the need for development of effective and reversible non-hormonal methods of male fertility control is widely recognized. Currently there are several contraceptive options available to men, however, none of the non-hormonal alternatives have been clinically approved. To advance progress in the development of a safe and reversible contraceptive for men, further identification of novel reproductive tract-specific druggable protein targets is required. Here we provide an overview of genes/proteins identified in the last decade as specific or highly expressed in the male reproductive tract, with deletion phenotypes leading to complete male infertility in mice. These phenotypes include arrest of spermatogenesis and/or spermiogenesis, abnormal spermiation, abnormal spermatid morphology, abnormal sperm motility, azoospermia, globozoospermia, asthenozoospermia, and/or teratozoospermia, which are all desirable outcomes for a novel male contraceptive. We also consider other associated deletion phenotypes that could impact the desirability of a potential contraceptive. We further discuss novel contraceptive targets underscoring promising leads with the objective of presenting data for potential druggability and whether collateral effects may exist from paralogs with close sequence similarity.

Male Hormonal Contraception

The economic and public health burdens of unplanned pregnancies are evident globally. Since the introduction of the condom >300 years ago, assumptions about male willingness to participate in contraception, as well as concerns about failure rates and side effects, have stagnated the development of additional reversible male contraceptives. However, changing attitudes and recent research advances have generated renewed interest in developing reversible male contraceptives. To achieve effective and reversible suppression of spermatogenesis, male hormonal contraception relies on suppression of testicular testosterone and sperm production using an androgen-progestin combination. While these may be associated with side effects—changes in libido, weight, hematocrit, and cholesterol—recently, novel androgens and progestins have shown promise for a “male pill” with reduced side effects. Here we summarize landmark studies in male contraceptive development, showcase the most recent advances, and look into the future of this field, which has the potential to greatly impact global public health.

Testosterone replacement therapy and cardiovascular risk

Testosterone is the main male sex hormone and is essential for the maintenance of male secondary sexual characteristics and fertility. Androgen deficiency in young men owing to organic disease of the hypothalamus, pituitary gland or testes has been treated with testosterone replacement for decades without reports of increased cardiovascular events. In the past decade, the number of testosterone prescriptions issued for middle-aged or older men with either age-related or obesity-related decline in serum testosterone levels has increased exponentially even though these conditions are not approved indications for testosterone therapy. Some retrospective studies and randomized trials have suggested that testosterone replacement therapy increases the risk of cardiovascular disease, which has led the FDA to release a warning statement about the potential cardiovascular risks of testosterone replacement therapy. However, no trials of testosterone replacement therapy published to date were designed or adequately powered to assess cardiovascular events; therefore, the cardiovascular safety of this therapy remains unclear. In this Review, we provide an overview of epidemiological data on the association between serum levels of endogenous testosterone and cardiovascular disease, prescription database studies on the risk of cardiovascular disease in men receiving testosterone therapy, randomized trials and meta-analyses evaluating testosterone replacement therapy and its association with cardiovascular events and mechanistic studies on the effects of testosterone on the cardiovascular system. Our aim is to help clinicians to make informed decisions when considering testosterone replacement therapy in their patients.

Validity and Clinically Meaningful Changes in the Psychosexual Daily Questionnaire and Derogatis Interview for Sexual Function Assessment: Results From the Testosterone Trials

BACKGROUND

Limited information is available on the performance characteristics of 2 questionnaires commonly used in clinical research, the Psychosexual Daily Questionnaire (PDQ) and the Derogatis Interview for Sexual Function (DISF)-II Assessment, especially in older men with low testosterone (T) and impaired sexual function.

AIM

To determine reliability of PDQ and DISF-II by assessing the correlation within and between domains in the questionnaires and to define clinically meaningful changes in sexual activity (PDQ question 4 [Q4]) and desire (DISF-II sexual desire domain [SDD]) domains.

METHODS

Data from 470 men participating in the T Trials were used to calculate Spearman correlation coefficients of individual items and total score among questionnaires to determine convergent and construct validity. Clinically meaningful changes for sexual desire and activity were determined by randomly dividing the sample into training and validation sets. Anchor- and distribution-based clinically meaningful change criteria were defined in the training set, and selected changes were evaluated in the validation set.

OUTCOMES

Validity of the PDQ and DISF-II and clinically meaningful changes in sexual desire and activity were determined in older men in T Trials.

RESULTS

Moderate to strong correlations were shown within and between domains from different questionnaires. Using Patient Global Impression of Change as an anchor, clinically meaningful change in PDQ sexual activity was ≥0.6, and in DISF-SDD was ≥5.0. Applying these change cut-points to the validation set, a greater proportion of T-treated men achieved clinically meaningful improvement in their sexual desire and activity compared to placebo-treated men.

CLINICAL IMPLICATIONS

The PDQ-Q4 and DISF-II-SDD can be used to reliably assess clinically meaningful changes in sexual activity and sexual desire in hypogonadal men treated with T.

STRENGTHS & LIMITATIONS

Strengths of this study include a large sample size, long trial duration, and inclusion of men with low libido and unequivocally low T levels. Limitations include using data from a single study that enrolled only older hypogonadal men, and only 1 anchor for both sexual desire and activity.

CONCLUSION

Moderate to strong correlations were demonstrated within and between different sexual domains of the PDQ and DISF-II confirming construct and convergent validity. Clinically meaningful improvement in elderly hypogonadal men was change of ≥0.6 score in the PDQ-Q4 and ≥5.0 in the DISF-SDD. Improvements in sexual activity and desire in the T Trials were modest but clinically meaningful. Wang C, Stephens-Shields AJ, DeRogatis LR, et al. Validity and Clinically Meaningful Changes in the Psychosexual Daily Questionnaire and Derogatis Interview for Sexual Function Assessment: Results From the Testosterone Trials. J Sex Med 2018;15:997-1009.

Male Contraceptive Development: Update on Novel Hormonal and Nonhormonal Methods

BACKGROUND

Development of new methods of male contraception would address an unmet need for men to control their fertility and could increase contraceptive options for women. Pharmaceutical research and development for male contraception was active in the 1990s but has been virtually abandoned. The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) has supported a contraceptive development program since 1969 and supports the majority of hormonal male contraceptive development. Nonhormonal methods are also in development but are at earlier stages.

CONTENT

Several hormonal male contraceptive agents have entered clinical trials. Single-agent products being evaluated include dimethandrolone undecanoate, 11β-methyl-nortestosterone dodecyl carbonate, and 7α-methyl-19-nortestosterone. A contraceptive efficacy trial of Nestorone^® gel and testosterone gel in a single application will begin in 2018. Potential nonhormonal methods are at preclinical stages of development. Many nonhormonal male contraceptive targets that affect either sperm production or sperm function have been identified. Targeted pathways include the retinoic acid pathway, bromodomain and extraterminal proteins, and pathways for Sertoli cell-germ cell adhesion or sperm motility. Druggable targets include CatSper, the sperm Na+/K+-exchanger, TSSK, HIPK4, EPPIN, and ADAMs family proteins. Development of a procedure to reversibly block the vas deferens (initially developed in India in the 1980s) is undergoing early stage research in the US under the trade name Vasalgel™.

SUMMARY

NICHD has supported the development of reversible male contraceptive agents. Other organizations such as the World Health Organization and the Population Council are pursuing male contraceptive development, but industry involvement remains dormant.

Recent Developments in Male Contraception

Unplanned pregnancies are an ongoing global burden, posing health and economic risks for women, children, and families. Advances in male contraception have been historically stymied by concerning failure rates, problematic side effects, and perceived market limitations. However, increased interest in reliable and reversible options for male contraception have resulted in resurgent efforts to introduce novel contraceptives for men. Hormonal male contraception relies on exogenous androgens and progestogens that suppress gonadotropin production, thereby suppressing testicular testosterone and sperm production. In many men, effective suppression of spermatogenesis can be achieved by androgen-progestin combination therapy. Small-scale contraceptive efficacy studies in couples have demonstrated effectiveness and reversibility with male hormonal methods, but side effects related to mood, sexual desire and cholesterol remain concerning. A number of novel androgens have reached clinical testing as potential contraceptive agents; many of these have both androgenic and progestogenic action in a single, modified steroid, thereby holding promise as single-agent contraceptives. Currently, these novel steroids hold promise as both a "male pill" and long-acting injections. Among non-hormonal methods, studies of reversible vaso-occlusive methods (polymers that block transport of sperm through the vas deferens) are ongoing, but reliable reversibility and long-term safety in men have not been established. Proteins involved in sperm maturation and motility are attractive targets, but to date both specificity and biologic redundancy have been challenges for drug development. In this review, we aim to summarize landmark studies on male contraception, highlight the most recent advances and future development in this important field of public health and medicine.

Male contraception: where are we going and where have we been?

Progress in developing new reversible male contraception has been slow. While the hormonal approach has been clearly shown to be capable of providing effective and reversible contraception, there remains no product available. Currently, trials of a self-administered gel combination of testosterone and the progestogen Nestorone® are under way, complementing the largely injectable methods previously investigated. Novel long-acting steroids with both androgenic and progestogenic activity are also in early clinical trials. The non-hormonal approach offers potential advantages, with potential sites of action on spermatogenesis, and sperm maturation in the epididymis or at the vas, but remains in preclinical testing. Surveys indicate the willingness of men, and their partners, to use a new male method, but they continue to lack that opportunity.

Reprint of: Beyond contraception and hormone replacement therapy: Advancing Nestorone to a neuroprotective drug in the clinic

Neurological diseases such as ischemic stroke can be debilitating and have limited treatments available. The progestin Nestorone® (segesterone acetate) has been evaluated for use in birth control and hormone replacement therapy due to its potency and high affinity for the progesterone receptor. Interestingly, Nestorone also exerts neuroprotection in animals afflicted with various central nervous system diseases, including stroke, which implicates its potential for treating these maladies in clinical settings. In fact, a recent Brain Research paper by Tanaka and colleagues demonstrates Nestorone's ability to reduce infarct sizes and preclude functional impairments in rats subjected to ischemic stroke. This commentary highlights Nestorone's properties as a progestin, its neuroprotective capabilities in animal studies, and how the Tanaka team's findings and previous clinical trials contribute to Nestorone's translation into a therapeutic agent for stroke and other neurological diseases.

Would male hormonal contraceptives affect cardiovascular risk?

The aim of hormonal male contraception is to prevent unintended pregnancies by suppressing spermatogenesis. Hormonal male contraception is based on the principle that exogenous administration of androgens and other hormones such as progestins suppress circulating gonadotropin concentrations, decreasing testicular Leydig cell and Sertoli cell activity and spermatogenesis. In order to achieve more complete suppression of circulating gonadotropins and spermatogenesis, a progestin has been added testosterone to the most recent efficacy trials of hormonal male contraceptives. This review focusses on the potential effects of male hormonal contraceptives on cardiovascular risk factors, lipids and body composition, mainly in the target group of younger to middle-aged men. Present data suggest that hormonal male contraception can be reasonably regarded as safe in terms of cardiovascular risk. However, as all trials have been relatively short (< 3 years), a final statement regarding the cardiovascular safety of hormonal male contraception, especially in long-term use, cannot be made. Older men with at high risk of cardiovascular event might not be good candidates for hormonal male contraception. The potential adverse effects of hormonal contraceptives on cardiovascular risk appear to depend greatly on the choice of the progestin in regimens for hormonal male contraceptives. In the development of prospective hormonal male contraception, data on longer-term cardiovascular safety will be essential.

Combined nestorone-testosterone gel suppresses serum gonadotropins to concentrations associated with effective hormonal contraception in men

BACKGROUND

Novel male-based contraceptives are needed to broaden family planning choices. A progestin, Nestorone^® (Nes) gel, plus a testosterone (T) gel suppresses sperm concentrations to levels associated with effective contraception in normal men. However, administration of two gels on different parts of the body daily is impractical.

OBJECTIVE

Compare the effectiveness of daily application of a single, combined 8.3 mg Nes-62.5 mg T gel (Nes-T) vs. 62.7 mg T gel to suppress serum FSH and LH concentrations to ≤1.0 IU/L (a threshold associated with suppression of sperm concentrations to ≤1 million and effective contraception) and to compare the pharmacokinetics of serum Nes and T concentrations between the gel groups.

DESIGN

We conducted a 28-day, double-blind, controlled trial of 44 healthy men randomized to daily Nes-T or T gel with measurement of hormones at baseline, treatment, and recovery and during 24-h pharmacokinetic studies on days 1 and 28 of treatment.

RESULTS

Of the subjects who met pre-defined inclusion criteria, 84% of the Nes-T group suppressed serum gonadotropin concentrations to ≤1.0 IU/L at days 21-28 vs. 16.7% in the T group (p < 0.001). On day 1, Nes concentrations rose significantly above baseline by 2 h and continued to rise up to 24 h after Nes-T gel application. Nes concentrations were not detectable in the T group. Serum total T concentrations rose and were significantly higher in the T gel group compared to the Nes-T group at 24 h on day 1 and days 11, 14, and 21 (p < 0.01). There were no serious adverse events in either group. About 80% of the subjects reported satisfaction with both gels.

CONCLUSION

Daily Nes-T gel effectively and safely suppresses serum gonadotropins and is acceptable to most men. It should be studied further in efficacy trials of hormonal male contraception.

F5-peptide enhances the efficacy of the non-hormonal male contraceptive adjudin

OBJECTIVE

The bioavailability of the non-hormonal male contraceptive adjudin is low in rats due to the blood-testis barrier (BTB). This study was designed to examine if F5-peptide, an endogenously produced reversible BTB modifier, could enhance the bioavailability of adjudin to affect spermatogenesis and provide a contraceptive effect in rats while reducing systemic toxicity.

STUDY DESIGN

We overexpressed F5-peptide in adult male rats (n=10 rats; with 3 or 4 rats for each of the three different experiments noted in the three regimens) by intratesticular injection of a mammalian expression vector pCI-neo (pCI-neo/F5-peptide) vs. empty vector alone (pCI-neo/Ctrl) to be followed by treatment with adjudin by oral gavage at a dose of 10 or 20 mg/kg. The status of spermatogenesis was assessed by histological analysis and dual-labeled immunofluorescence analysis on Day 16. To assess fertility, we allowed treated males (n=3-4 rats) to mate with mature female rats (n=3-4) individually, and assessed the number of pups on Days 23, 36 and 82 to assess fertility and reversibility.

RESULTS

All 4 treated rats overexpressed with F5-peptide and low-dose adjudin were infertile by Day 36, and half of these rats were fertile by Day 82, illustrating reversibility. However, overexpression of F5-peptide alone (or low-dose adjudin alone) had no effects on fertility in n=3 rats. These findings were consistent with the histology data that illustrated the BTB modifier F5-peptide promoted the action of adjudin to induce germ cell exfoliation, mediated by changes in cytoskeletal organization of F-actin and microtubules across the epithelium, thereby reducing the systemic toxicity of adjudin.

CONCLUSION

In this proof-of-concept study, it was shown that overexpression of the F5-peptide prior to administration of adjudin to rats at a low (and ineffective dose by itself) was found to induce reversible male infertility.

IMPLICATIONS

Overexpression of F5-peptide, an endogenously produced biomolecule in the testis known to induce BTB remodeling, enhanced the contraceptive effect of adjudin in rats, supporting proof of concept studies of BTB disrupters in men.

Update on male hormonal contraception

Despite increases in female contraceptive options, 40-45% of pregnancies across the world are still unplanned. While several effective female contraceptive methods have been developed, contraceptive choices for men are still limited to the male condom with its high failure rates and to vasectomies, which are invasive and not reliably reversible. Several studies have demonstrated a great interest among men and women for effective, reversible, and safe male contraceptive methods. Over the years, numerous studies have been performed to develop male hormonal and nonhormonal safe and effective contraceptives. A variety of new molecules are under development as oral or transdermal hormonal contraceptives for men demonstrating few side effects. In our overpopulated world, the development and commercialization of a male contraceptive method that will allow both men and women to take an active role in family planning is mandatory and further research on this topic is required.

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 (C_avg ).

RESULTS

Median female serum T C_avg 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 C_avg 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.

Testosterone Is a Contraceptive and Should Not Be Used in Men Who Desire Fertility

Testosterone has a variety of functions and is commonly used in older men to treat symptoms of hypogonadism, such as decreased libido, decreased mood and erectile dysfunction. Despite its positive effects on sexual function, it has a negative effect on fertility. Exogenous testosterone therapy can negatively affect the hypothalamic-pituitary gonadal axis and inhibit the production of follicle stimulating hormone and luteinizing hormone. The purpose of this review is to discuss the contraceptive properties of testosterone therapy and to discuss strategies to increase testosterone in men with the desire to preserve fertility.

Therapeutic progestin segesterone acetate promotes neurogenesis: implications for sustaining regeneration in female brain

OBJECTIVE

Neurogenesis is the principal regenerative mechanism to sustain the plasticity potential in adult brains. Decreased neurogenesis parallels the cognition decline with aging, and has been suggested as a common hallmark in the progression of many neurodegeneration diseases. We previously reported that acute exposure to segesterone acetate (ST-1435; Nestorone), alone or in combination with 17β-estradiol (E2), increased human neural stem cells proliferation and survival both in vitro and in vivo. The present study expanded our previous findings to investigate the more clinical related chronic exposure in combination with E2 on the regenerative capacity of adult brain.

METHODS

To mimic the chronic contraception exposure in women, 3-month old female mice (n = 110) were treated with ST-1435, with or without co-administration of E2, for 4 weeks. Neural cell proliferation and survival, and oligodendrocyte generation were assessed. The involvement of insulin-like growth factor 1 signaling was studied.

RESULTS

Our results demonstrated that chronic ST-1435 and E2 alone or in combination increased neurogenesis by a comparable magnitude, with minimum to no antagonistic or additive effects between ST-1435 and E2. In addition, chronic exposure of ST-1435 or ST-1435 + E2 stimulated oligodendrocyte generation, indicating potential elevated myelination. Insulin-like growth factor-1 (IGF-1) and IGF-1 receptor (IGF-1R) were also up-regulated after chronic ST-1435 and E2 exposure, suggesting the involvement of IGF-1 signaling as the potential underlined regulatory pathway transducing ST-1435 effect.

CONCLUSION

These findings provide preclinical evidence and mechanistic insights for the development of ST-1435 as a neuroregenerative therapy to promote intrinsic regenerative capacity in female brains against aging and neurodegenerative disorders.

Can the evolution of male contraception lead to a revolution? Review of the current state of knowledge

Introduction

Great advances in medical research concerning methods of contraception have been achieved in recent years, however, more than 25% of couples worldwide still rely on condoms - a method with poor efficacy. Even though there is a spectrum of 11 different contraceptive methods for women, there are only 4 commonly used by men (condoms, periodic abstinence, withdrawal and vasectomy). In this review, advances and present, state-of-the-art, both hormonal and non-hormonal male contraceptive methods will be presented and evaluated. Potential novel targets that warrant greater research will be highlighted.

Material and methods

A comprehensive literature search without a time limit was performed using the Medline database on May 2017. The terms 'male contraception' in conjunction with 'reversible inhibition of sperm under guidance' (RISUG), 'hormonal', 'non-hormonal', 'vasectomy' or 'testosterone' were used. The articles were limited to those published in English, Polish or French.

Results

There are various contraceptives currently available to regulate male fertility. Vasectomy is still the most effective permanent form of male contraceptive with a failure rate lower than 1%. Reversible, non hormonal methods of male contraception, like reversible inhibition of sperm under guidance, are very promising and close to being introduced into the market. In regards to hormonal contraception research, the use of testosterone injections has been widely studied yet they often harbor undesirable side effects and require further development.

Conclusions

Despite continuous efforts worldwide, it seems that another several years of research is needed to provide safe, effective and affordable male contraceptives which will allow both men and women to participate fully in family planning.

Male hormonal contraception: hope and promise

Family planning is a shared responsibility, but available male-directed contraceptive methods are either not easily reversible (vasectomy) or not sufficiently effective (condom). However, roughly 20% of couples using a contraceptive method worldwide, and up to 80% in some countries, still choose a male-directed method. Male hormonal contraception is highly effective, with perfect use failure rates of 0·6% (95% CI 0·3-1·1) if sperm concentrations of less than 1 million per mL are maintained. After cessation of male hormonal contraception, sperm output fully recovers in a predictable manner, resulting in pregnancies and livebirths. Spontaneous miscarriage and fetal malformation rates after recovery of sperm output overlap those in the general population. Short-term adverse events-acne, night sweats, increased weight, and altered mood and libido-are recognised, but are generally mild. Further optimisation of specific androgen-progestin regimens and phase 3 studies of lead combinations are still needed to successfully develop an approved male hormonal contraceptive and to identify long-term side-effects.

Hormonal, chemical and thermal inhibition of spermatogenesis: contribution of French teams to international data with the aim of developing male contraception in France

Since the 1970s, international research on male contraception has been actively pursued. Hormonal and non-hormonal methods (thermal, chemical) have been tested, leading to clinical trials of interest to thousands of men and couples. The results showed that it was possible to develop methods of male contraception that inhibited spermatogenesis with good contraceptive efficacy. However, their side effects (mainly loss of libido), poorly accepted modes of administration, and the high frequency of poor responders prevented their widespread use. Based on earlier initiatives, new avenues were explored and significant progress was achieved, allowing the reasoned use of male contraception. For 40 years, several French teams have played an important role in this research. The aim of this paper is to outline the history and the progress of the experimental and clinical works of these teams who addressed hormonal, chemical and thermal approaches to male contraception. These approaches have led to a better comprehension of spermatogenesis that could be useful in fields other than male contraception: effects of toxic compounds, fertility preservation.

Pipeline for contraceptive development

The high rates of unplanned pregnancy reflect an unmet need for effective contraceptive methods for women, especially for individuals with health risks such as obesity, diabetes, hypertension, and other conditions that may contraindicate use of an estrogen-containing product. Improvements in safety, user convenience, acceptability, and availability of products remain important goals of the contraceptive development program. Another important goal is to minimize the impact of the products on the environment. Development of new methods for male contraception has the potential to address many of these issues of safety for women who have contraindications to effective contraceptive methods but want to protect against pregnancy. It would also address a huge unmet need for men who want to control their fertility. Products under development for men would not introduce ecotoxic hormones into the water system.

Male contraception

Although female contraceptives are very effective at preventing unintended pregnancy, some women can not use them because of health conditions or side-effects, leaving some couples without effective contraceptive options. In addition, many men wish to take active responsibility for family planning. Thus, there is a great need for male contraceptives to prevent unintended pregnancies, of which 80-90 million occur annually. At present, effective male contraceptive options are condoms and vasectomy, which are not ideal for all men. Therefore, efforts are under way to develop novel male contraceptives. This paper briefly reviews the advantages and disadvantages of condoms and vasectomies and then discusses the research directed toward development of novel methods of male contraception.

Recombinant production of enzymatically active male contraceptive drug target hTSSK2 - Localization of the TSKS domain phosphorylated by TSSK2

The testis-specific serine/threonine kinase 2 (TSSK2) has been proposed as a candidate male contraceptive target. Development of a selective inhibitor for this kinase first necessitates the production of highly purified, soluble human TSSK2 and its substrate, TSKS, with high yields and retention of biological activity for crystallography and compound screening. Strategies to produce full-length, soluble, biologically active hTSSK2 in baculovirus expression systems were tested and refined. Soluble preparations of TSSK2 were purified by immobilized-metal affinity chromatography (IMAC) followed by gel filtration chromatography. The biological activities of rec.hTSSK2 were verified by in vitro kinase and mobility shift assays using bacterially produced hTSKS (isoform 2), casein, glycogen synthase peptide (GS peptide) and various TSKS peptides as target substrates. Purified recombinant hTSSK2 showed robust kinase activity in the in vitro kinase assay by phosphorylating hTSKS isoform 2 and casein. The ATP Km values were similar for highly and partially purified fractions of hTSSK2 (2.2 and 2.7 μM, respectively). The broad spectrum kinase inhibitor staurosporine was a potent inhibitor of rec.hTSSK2 (IC50 = 20 nM). In vitro phosphorylation experiments carried out with TSKS (isoform 1) fragments revealed particularly strong phosphorylation of a recombinant N-terminal region representing aa 1-150 of TSKS, indicating that the N-terminus of human TSKS is phosphorylated by human TSSK2. Production of full-length enzymatically active recombinant TSSK2 kinase represents the achievement of a key benchmark for future discovery of TSSK inhibitors as male contraceptive agents.