Demand for male contraception

The uniqueness of on-demand male contraception

Because nearly half of pregnancies worldwide are unintended, available contraceptive methods are inadequate. Moreover, due to the striking imbalance between contraceptive options available for men compared to the myriad of options available to women, there is an urgent need for new methods of contraception for men. This review summarizes ongoing efforts to develop male contraceptives highlighting the unique aspects particular to on-demand male contraception, where a man takes a contraceptive only when and as often as needed.

Ca2+ homeostasis and male fertility: a target for a new male contraceptive system

Ca2+ is a key secondary messenger that determines sperm motility patterns. Mammalian sperm undergo capacitation, a process to acquire fertilizing ability, in the female reproductive tract. Capacitated sperm change their flagellar waveform to develop hyperactivated motility, which is crucial for successful sperm navigation to the eggs and fertilization. The sperm-specific channel, CATSPER, and an ATPase transporter, PMCA4, serve as major paths for Ca2+ influx and efflux, respectively, in sperm. The ionic paths coordinate Ca2+ homeostasis in the sperm, and their loss-of-function impairs sperm motility, to cause male infertility. In this review, we summarize the physiological significance of these two Ca2+ gates and suggest their potential applications in novel male contraceptives.

Nonhormonal Male Contraceptive Development-Strategies for Progress

Despite the widely demonstrated public health benefits of contraception, limited contraceptive options are available for men, placing both the contraceptive burden and opportunity solely on women. This review outlines the need for an increased focus on male contraceptive development and highlights several related topics, including the perspectives of women and men on male contraceptives, historical challenges, and reasons behind the persistent delays in male contraceptive development. It also discusses the importance of serendipitous observations in drug discovery and the limitations of depleting sperm or spermatogenic cells as a contraceptive approach. It further provides an overview of ongoing research and development on novel methods, with a goal to offer insights into the multifaceted aspects of nonhormonal male contraceptive development, addressing its implications for the health of men and women. SIGNIFICANCE STATEMENT: Despite well over half a century of effort in developing male contraceptives, there are no approved male contraceptive drugs on the market. This review aims to present strategies for progress in nonhormonal male contraception based on lessons learned from history, with the hope of expediting development and bringing a male contraceptive drug closer to reality.

Bacterial production of recombinant contraceptive vaccine antigen from CatSper displayed on a human papilloma virus-like particle

CatSper is a voltage dependent calcium ion channel present in the principal piece of sperm tail. It plays a crucial role in sperm hyperactivated motility and so in fertilization. Extracellular loops of mouse sperm CatSper were used to develop a vaccine to achieve protection from pregnancy. These loops were inserted at one of the three hypervariable regions of Human Papilloma Virus (HPV) capsid protein (L1). Recombinant vaccines were expressed in E.coli as inclusion body (IB), purified, refolded and assembled into virus-like particles (VLP) in vitro, and adsorbed on alum. Four vaccine candidates were tested in Balb/C mice. All the constructs proved immunogenic, one showed contraceptive efficacy. This recombinant contraceptive vaccine is a non-hormonal intervention and is expected to give long-acting protection from undesired pregnancies.

A global grounded theory exploration of investigators' perspectives on male hormonal contraceptive development and acceptability

While best practices have been proposed on how to engage men in family planning (FP), the limited options of male hormonal contraceptives (MHC) are a barrier to reaching men as clients of FP programs. The lack of alternative MHC is preventing the global health community from providing holistic reproductive healthcare. A qualitative grounded theory study was conducted in 2020 to explore MHC experts' perceptions around the development and theoretical acceptability of MHCs. Individual in-depth interviews were conducted with 15 key informants. The informants cited evidence that there is a demand for MHC. The inability to access this data by the pharmaceutical industry was acknowledged. Many informants expressed concern of the possibility for MHC to increase male power in a predominantly patriarchal world. To most informants, at least for the initial introduction of MHC, fertility sharing is something that will largely happen among couples alone rather than individually. There is proven demand among women and men for MHC, however industries may still be reluctant to invest. Effort is needed by the sexual and reproductive health and rights community to include male engagement in FP and to advocate for the development and use of MHC as a tool for women's empowerment.

Role of testis‑specific serine kinase 1B in undiagnosed male infertility

Male infertility is a global problem affecting a considerable part of the male population. Current guidelines and practices aimed at diagnosing the cause of this problem still have low diagnostic yield. As novel candidate genes for infertility emerge, their functional role needs to be investigated in patient populations. The present study aimed to investigate testis-specific serine kinase 1B (TSSK1B), which was discovered in a previously diagnosed patient. Sanger sequencing of the coding regions and exon borders of TSSK1B was performed in a cohort of 100 male Bulgarian patients with unresolved infertility causes. Missense mutations were discovered in 10% of patients and were associated with clinical data on sperm dysmorphology. Two previously unreported mutations were discovered, p.3D>N and p.52F>L. All mutations were scored via in silico predictors and protein modelling using AlphaFold2. The present findings indicated an association between TSSK1B mutations and asthenoteratozoospermia, with further missense mutations in patients with azoospermia and teratozoospermia. Mutations in TSSK1B may be a cause of undiagnosed cases of male infertility and should be considered when molecular diagnostics are warranted.

Still no pill for men? Double standards & demarcating values in biomedical research

Double standards are widespread throughout biomedicine, especially in research on reproductive health. One of the clearest cases of double standards involves the feminine gendering of reproductive responsibility for contraception and the continued lack of highly effective, reversible methods for cisgender men. While the biomedical establishment accepts diversity and inclusion as important social values for clinical trials, their continued use of inequitable standards undermines their ability to challenge unfair social hierarchies by developing male contraception. Thus, the gender/sex bias present in contraceptive research raises the "New Demarcation Problem": If we accept that values can and will play important roles in science, how can we nevertheless distinguish positive influences of values from more corrosive bias? I argue that biomedical researchers ought to aim their clinical trials at equity and utilize methodologies that actually achieve that aim. More specifically, I contend that we can avoid the problem of double standards by gender/sex in contraceptive research by utilizing more equitable standards. My demarcation strategy captures dynamic interplay between values and their effects, with direct policy implications for institutions conducting, funding, and evaluating clinical trials. For male contraceptive trials, this involves shifting risk assessment from an individual model to a shared model for sexual partners.

A long way to go: engagement of men and boys in country family planning commitments and implementation plans

Background: To reach global goals related to women and girls’ access to modern family planning (FP) and gender equality, evidence shows that it is critical to understand and account for the role of men and boys as users of reproductive health services, as partners for millions of women & girls around the world, and as advocates in their communities. Under the Family Planning 2020 (FP2020) partnership, countries were encouraged to develop costed implementation plans and action plans in an effort to provide 120 million additional women and girls with contraception. As FP2020 becomes FP2030, reviewing these previously-developed strategies helps understand the extent to which countries considered the engagement of men as an important aspect of their family planning portfolios.

Methods: We conducted textual analysis on commitments and implementation plans related to achieving FP2020 commitments in six countries in Africa and one in Asia to determine the extent to which male engagement was incorporated into country or subnational family planning goals, with particular focus on FP policy, program, and financial commitments. 

Results: Some of the documents analyzed included robust plans for including male engagement in their efforts to expand access to FP.  The strongest aspects of male engagement programming were those that sought to engage men as advocates for women’s access to and use of FP services, and improve their knowledge and attitudes related to contraception and reproduction. The weakest aspects were engaging men as users of services and, vitally, tackling underlying gender norms which hamper men’s and women’s health-seeking behaviors and attitudes.

Conclusions: Developing FP programs that target men and boys as people deserving of reproductive health services, as partners with women in building their families, and as social activists in their communities, will complement and strengthen existing FP programs as well as promote broader goals related to gender equality.

A long way to go: engagement of men and boys in country family planning commitments and implementation plans

Background: Evidence shows that, to reach global goals related to women and girls' access to modern family planning (FP) and gender equality, it is critical to understand and account for the role of men and boys as users of reproductive health services, as partners for millions of women & girls around the world, and as advocates in their communities. Under the Family Planning 2020 (FP2020) partnership, countries were encouraged to develop costed implementation plans and action plans in an effort to provide 120 million additional women and girls with contraception. As FP2020 becomes FP2030, reviewing these previously-developed strategies helps understand the extent to which countries considered the engagement of men as an important aspect of their family planning portfolios. Methods: We conducted textual analysis on commitments and implementation plans related to achieving FP2020 commitments in seven countries in Africa and one in Asia to determine the extent to which male engagement was incorporated into country or subnational family planning goals, with particular focus on FP policy, program, and financial commitments.  Results: Some of the documents analyzed included robust plans for including male engagement in their efforts to expand access to FP.  The strongest aspects of male engagement programming were those that sought to engage men as advocates for women's access to and use of FP services, and improve men's knowledge and attitudes related to contraception and reproduction. The weakest aspects were engaging men as users of services and, vitally, tackling underlying gender norms which hamper men's and women's health-seeking behaviors and attitudes. Conclusions: Developing FP programs that target men and boys as people deserving of reproductive health services, as partners with women in building their families, and as social activists in their communities, will complement and strengthen existing FP programs as well as promote broader goals related to gender equality.

Online community queries on hormonal male contraception: An analysis of the Reddit "Ask Me Anything" experience

OBJECTIVE

Reddit is one of the most popular websites in the United States because of its user-driven aggregation and community-based curation of online content. We describe the use and impact of Reddit's Ask Me Anything platform, for public engagement and education about developments in hormonal male contraception (HMC).

METHODS

We analyzed the content from and user engagement with 2 Reddit Ask Me Anything events that answered user queries about HMC in June 2018 and March 2019. Clinical trial investigators provided real-time responses throughout the events. We examined the 25 most popular posts from each event, analyzing content for salient themes via an inductive approach. To quantify event impact, we examined Google Trends data and subsequent traffic to the investigator website.

RESULTS

Over 18,000 registered Reddit users interacted with each of the 2 Ask Me Anything events, with each generating over 1600 comments. The most popular posts of each Ask Me Anything event expressed interest in off-target effects associated with the use of HMCs. Additional themes included queries about previous and ongoing clinical trials, HMC physiology, and market analyses and projections of public willingness to use HMCs. The events coincided with a spike in both Google searches for "male birth control" and first-time visits to the study's website where users could express interest in participating in clinical trials.

CONCLUSION

Reddit Ask Me Anything events conducted by HMC investigators revealed wide public interest in HMCs. The events prompted further searches for more information on male contraception, while driving traffic to the investigator website for trial recruitment purposes.

IMPLICATIONS

Reddit Ask Me Anything events are a popular, cost-free online platform for publicly responding to a range of HMC-related queries, while providing investigators with insight into stakeholder priorities and preoccupations.

The Na+ and K+ transport system of sperm (ATP1A4) is essential for male fertility and an attractive target for male contraception†

One of the mechanisms that cells have developed to fulfil their specialized tasks is to express different molecular variants of a particular protein that has unique functional properties. Na,K-ATPase (NKA), the ion transport mechanism that maintains the transmembrane Na+ and K+ concentrations across the plasma membrane of cells, is one of such protein systems that shows high molecular and functional heterogeneity. Four different isoforms of the NKA catalytic subunit are expressed in mammalian cells (NKAα1, NKAα2, NKAα3, and NKAα4). NKAα4 (ATP1A4) is the isoform with the most restricted pattern of expression, being solely produced in male germ cells of the testis. NKAα4 is abundant in spermatozoa, where it is required for sperm motility and hyperactivation. This review discusses the expression, functional properties, mechanism of action of NKAα4 in sperm physiology, and its role in male fertility. In addition, we describe the use of NKAα4 as a target for male contraception and a potential approach to pharmacologically block its ion transport function to interfere with male fertility.

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.

The future of male contraception: a fertile ground

The continued and rapid expansion of the Earth’s population mandates the need for safe and effective measures of contraception. While a plethora of options exist for women, methods of contraception for the male partner are limited to condoms and vasectomy. The sequela of this discrepancy has led to the family planning burden falling disproportionately on the female partner. For the past several decades, extensive research has been undertaken exploring the feasibility of hormonal male contraception. This proposed method of contraception has focused on suppressing spermatogenesis by exploiting the hypothalamic-pituitary-gonadal (HPG) axis. Beginning with proof of concept studies in the early nineties, administration of testosterone in healthy male subjects has been shown to be an efficacious method of inducing sterility. Owing to ethnic differences in spermatogenesis suppression and the comparatively low rate of azoospermia in Caucasian men with androgen-only regimens, investigators have explored the addition of progestins to further enhance the efficacy of hormonal contraception. Though studies have revealed promise with androgen-progestin regimens, the lack of long-term studies has precluded the development of a marketable product. Recently, more research has been directed towards identifying non-hormonal alternatives to male contraception. These non-hormonal options have ranged from the development of devices facilitating reversible occlusion of the vas deferens lumen to medications disrupting various pathways in the process of spermatogenesis. Underlying the development of hormonal and non-hormonal strategies is the shared enthusiasm men and women have towards these male directed methods. The willingness of couples to pursue these alternatives combined with the global need to reduce the psychological and socioeconomic implications of unintended pregnancy ensures that research will continue to bring this goal to fruition.

Design, Synthesis, and in Vitro and in Vivo Evaluation of Ouabain Analogues as Potent and Selective Na,K-ATPase α4 Isoform Inhibitors for Male Contraception

Na,K-ATPase α4 is a testis-specific plasma membrane Na⁺ and K⁺ transporter expressed in sperm flagellum. Deletion of Na,K-ATPase α4 in male mice results in complete infertility, making it an attractive target for male contraception. Na,K-ATPase α4 is characterized by a high affinity for the cardiac glycoside ouabain. With the goal of discovering selective inhibitors of the Na,K-ATPase α4 and of sperm function, ouabain derivatives were modified at the glycone (C3) and the lactone (C17) domains. Ouabagenin analogue 25, carrying a benzyltriazole moiety at C17, is a picomolar inhibitor of Na,K-ATPase α4, with an outstanding α4 isoform selectivity profile. Moreover, compound 25 decreased sperm motility in vitro and in vivo and affected sperm membrane potential, intracellular Ca²⁺, pH, and hypermotility. These results proved that the new ouabagenin triazole analogue is an effective and selective inhibitor of Na,K-ATPase α4 and sperm function.

Reversibility of Vasalgel™ male contraceptive in a rabbit model

BACKGROUND

Development of a non-hormonal long-acting reversible contraceptive for men could have a significant impact on reducing unintended pregnancies. Vasalgel™ is a high molecular weight polymer consisting of styrene-alt-maleic acid (SMA) dissolved in dimethyl sulfoxide being developed as a reversible male contraceptive device. It forms a hydrogel when implanted into the vasa deferentia, which prevents the passage of sperm. Previous studies in the rabbit have proven its efficacy, durability and rapid onset. This study evaluates the capacity to restore sperm concentrations in ejaculates after a reversal procedure.

METHODS

Sodium bicarbonate was injected into the vasa deferentia after fourteen months of azoospermia following the injection of two device variations (Vasalgel 100 and Vasalgel 80). Semen samples were then collected for six months and sperm characteristics were compared to baseline levels. Samples of vasa deferentia were obtained for histological examination.

RESULTS

Spermatozoa were present in all subject ejaculates after the reversal procedure. Sperm concentration and sperm motility were similar to baseline levels after reversal, while sperm forward progression was significantly lower and normal acrosomes were not observed. Forward progression percentages increased linearly during six months of semen collection, however, normal acrosomes were not observed at the conclusion of the study. Histologically, several vasa deferentia were clear of the device and contained an intact epithelial lining. A smaller proportion of tissues contained residual test material. A secondary intraluminal inflammatory response was seen occasionally in the tissues containing residual material. There was no difference between the two device variations for studied parameters.

CONCLUSIONS

Vasalgel's prevention of sperm transport for 14 months was reversed through an intravasal injection of sodium bicarbonate. Post-reversal sperm concentrations and motility returned to baseline levels during the six-month follow up. Residual material in the vas lumen or compromised epididymal and vas deferens function may be resulting in reduced forward progression and loss of acrosomes during transit through the vas. Reduced forward progression and the lack of normal acrosomes strongly suggest impaired sperm function.

Are men well served by family planning programs?

Although the range of contraceptives includes methods for men, namely condoms, vasectomy and withdrawal that men use directly, and the Standard Days Method (SDM) that requires their participation, family planning programming has primarily focused on women. What is known about reaching men as contraceptive users? This paper draws from a review of 47 interventions that reached men and proposes 10 key considerations for strengthening programming for men as contraceptive users. A review of programming shows that men and boys are not particularly well served by programs. Most programs operate from the perspective that women are contraceptive users and that men should support their partners, with insufficient attention to reaching men as contraceptive users in their own right. The notion that family planning is women’s business only is outdated. There is sufficient evidence demonstrating men’s desire for information and services, as well as men’s positive response to existing programming to warrant further programming for men as FP users. The key considerations focus on getting information and services where men and boys need it; addressing gender norms that affect men’s attitudes and use while respecting women’s autonomy; reaching adolescent boys; including men as users in policies and guidelines; scaling up successful programming; filling gaps with implementation research and monitoring & evaluation; and creating more contraceptive options for men.

Prolonged Oral Administration of a Pan-Retinoic Acid Receptor Antagonist Inhibits Spermatogenesis in Mice With a Rapid Recovery and Changes in the Expression of Influx and Efflux Transporters

We have previously shown that oral administration of a pan-retinoic acid receptor antagonist in mice daily at 2.5 mg/kg for 4 weeks reversibly inhibited spermatogenesis, with no detectable side effects. To elucidate the lowest dose and the longest dosing regimen that inhibits spermatogenesis but results in complete restoration of fertility upon cessation of administration of the drug, we examined the effects of daily doses as low as 1.0 mg/kg with dosing periods of 4, 8, and 16 weeks. We observed 100% sterility in all regimens, with restoration of fertility upon cessation of the drug treatment even for as long as 16 weeks. There was no change in testosterone levels in these males and the progeny examined from 2 of the recovered males were healthy and fertile, with normal testicular weight and testicular histology. Strikingly, a more rapid recovery, as assessed by mating studies, was observed at the lower dose and longer dosing periods. Insight into possible mechanisms underlying this rapid recovery was obtained at 2 levels. First, histological examination revealed that spermatogenesis was not as severely disrupted at the lower dose and with the longer treatment regimens. Second, gene expression analysis revealed that the more rapid recovery may involve the interplay of ATP-binding cassette efflux and solute carrier influx transporters in the testes.

Azoospermia in rabbits following an intravas injection of Vasalgel ™

BACKGROUND

Vasectomy is currently the only long-acting contraceptive option available for men, despite increasing demand and potentially significant positive impacts on human health of additional male contraceptive options. Vasalgel ™ is a high molecular weight hydrogel polymer being developed as a non-hormonal long-acting reversible male contraceptive. Vasalgel consists of styrene-alt-maleic acid dissolved in dimethyl sulfoxide, which is distinct from styrene-alt-maleic anhydride materials previously studied.

METHODS

The goal of the study was to determine the contraceptive efficacy of two test articles with different levels of styrene maleic acid (100 %, and 80 % acid/20 % anhydride). The test articles were injected bilaterally in the vasa deferentia of mature male rabbits. Post-implantation analyses of semen parameters were completed over a 12 month period and compared to baseline measures of sperm concentration, motility and forward progression.

RESULTS

Both test articles were effective in blocking the passage of spermatozoa through the vasa deferentia in the 12 subjects completing the study. A significant decrease in sperm concentration occurred following implantation of the test material, with no measurable sperm concentration except for a few samples in one animal that were markedly oligospermic. Vasalgel produced a rapid onset of azoospermia, with no sperm in semen samples collected as early as 29-36 days post-implantation, and was durable over a 12 month period.

CONCLUSION

This study indicated that Vasalgel is an effective non-hormonal long-acting male contraceptive in a rabbit model.

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.

Male hormonal contraception: looking back and moving forward

Despite numerous contraceptive options available to women, approximately half of all pregnancies in the United States and worldwide are unplanned. Women and men support the development of reversible male contraception strategies, but none have been brought to market. Herein we review the physiologic basis for male hormonal contraception, the history of male hormonal contraception development, currents agents in development as well as the potential risks and benefits of male hormonal contraception for men.

Male Contraception: Research, New Methods, and Implications for Marginalized Populations

The majority of research on contraception has focused on manipulating the female reproductive system. Recent studies have identified novel contraceptives for males, including hormonal- and nonhormonal-based therapeutics. Although these new contraceptives are still undergoing clinical trials, their development and potential future use in society necessitate serious consideration of their implications for reproductive health. Through my analysis of the research conducted on male contraception over time and the current therapeutics available, it is clear that male contraception has the potential to shift societal gender dynamics and provide males with greater control over their own reproduction. This article also identifies the implications of these novel contraceptives for marginalized populations, especially men of color and men of lower socioeconomic positions. To overcome barriers to contraception among these populations, public policy efforts are needed in order to motivate the development of programs that facilitate coverage of these new male contraceptives by health plans and to increase their availability to underserved communities. Health care providers will be responsible for educating patients about these novel male contraception options and the need to continue using existing methods (e.g., condoms) in order to prevent sexually transmitted infections. This article analyzes the research conducted on male contraception and identifies the implications of these novel therapeutics for marginalized groups of men in the United States to identify the interventions that will be necessary to help ensure that all men have access to these promising scientific innovations.

Human spermatozoa: revelations on the road to conception

Human spermatozoa are highly complex specialized cells designed to survive a long and perilous journey from the site of insemination to the upper reaches of the female reproductive tract where fertilization occurs. During this journey, these cells have to run the gauntlet laid down by the female immune system and time their physiological maturation so that as soon as an egg appears in the Fallopian tube, they are equipped to recognize this cell and participate in a remarkable cascade of cellular interactions culminating in fertilization. Despite their high level of specialization, human spermatozoa are notoriously inadequate and appear to be major contributors to the poor fertility that characterizes our species. Defective spermatozoa are also known to have a major impact on the progress of pregnancy and the health trajectory of the offspring, resulting in paternally mediated increases in miscarriage rate and a range of diseases in the progeny, including dominant genetic diseases and cancer. The causes of defective sperm function are complex and involve both genetic and environmental impacts, as well as paternal age. Where genetic factors are involved, there is a concern that the widespread use of assisted conception technologies will serve to enhance the retention of poor fertility genes in the population such that the more we use assisted reproductive technologies in one generation the more we shall need them in the next. These observations may have important implications for the health and well-being of children and for the provision of reproductive healthcare services for future generations.