Infertility is a global health issue affecting up to 186 million people worldwide. Among them, up to 48 million couples (10-15 percent) need medical support (Ombelet, 2020). From a demographic perspective, most countries are in a phase of population decline with a total fertility rate belowthe required rate to keep a stable population size, from 5.1 in 1965 to 2.3 in 2021 (Dessouroux & Vandermotten, 2024). Males and females are equally responsible for these infertility issues. There are various treatment strategies and a few approved drugs for females, but there is no approved treatment for male infertility. The consequence is that only the woman can undergo one or more fertility stimulation treatments, even in cases of male infertility.
Moreover, hormonal treatments available for female patients are old – discovered in the 1960s and first used in the 1980s. Since their inception, ovarian stimulation treatments have involved daily injections of FSH (follicle stimulating hormone) for 12 to 14 days. FSH is a pituitary glycoprotein hormone that was first used in extracted form and then in recombinant form for the past 30 years. It is the key hormone involved in gametogenesis in both men and women.
However, FSH-based treatments are burdensome and not always effective. According to data from ICMART (2018), the birth rate is only 23.8 percent per treatment cycle for in vitro fertilization (IVF) and the cumulative birth rate is 37.3 percent (Baker et al., 2025). In the case of “poor responders”, the birth rate may be lower even with high doses of FSH (Bastu et al., 2016).
Additionally, infertility treatment is seldom covered by health insurance, and many couples must pay for it out of pocket, making it inaccessible. Therefore, there is a strong need for more effective treatment from a cost/efficiency ratio perspective.
I want to share some research from my team and I. We have demonstrated a very interesting concept in animals, namely that an antibody specific to a hormone could potentiate and increase the activity of that hormone. Indeed, previous results demonstrated that breeding female animals (ewes) treated with eCG (equine Chorionic Gonadotropin) to stimulate ovulation could develop special anti-eCG antibodies that enhance eCG bioactivity instead of inhibiting it. In this case, the eCG-treated females had a higher kidding (birth) rate and were sometimes hyperprolific despite high levels of anti-eCG antibodies.
What a marvellous molecule an antibody is. It has a high specificity and affinity which allows it to target its antigen among millions of other molecules. Therapeutic antibodies are very efficient because of their high specificity compared with small molecules, which can cross-react with several off-targets. Furthermore, depending on their epitope, therapeutic antibodies can either inhibit its antigen (the most common case) or enhance it (the much rarer case). An antibody is a flexible molecule that can induce a change in the conformation of its antigen, leading to a modulation of its activity that can result in a potentiating effect. The manufacturing of monoclonal antibodies is now well established and optimized, resulting in good productivity and stability without excessive risk.
Several therapeutic antibodies have been developed as biopharmaceutical products to treat infertility. Denosumab, a monoclonal anti-RANKL antibody initially developed by Amgen for the treatment of osteoporosis, has also been tested in the field of reproduction, particularly for treating infertility in men with non-Obstructive Azoospermia.
There is also GM102, a monoclonal antibody that targets Anti-Müllerian Human Receptor II (AMHRII). AMHRII is an unaddressed specific target in cancer and was tested to treat ovarian cancer.
IGX12 is another monoclonal antibody that enhances the bioactivity of FSH to address fertility issues in humans. As FSH stimulates gametogenesis both in men and women, IGX12 has the potential to treat both female and male infertility, offering a more effective and targeted solution for patients in a simpler, more affordable way the reduces the burden borne by women. Indeed, the qualities of IGX12 have been verified in multiple in vitro and in vivo animal models. The drug is capable of increasing FSH bioactivity in a male animal model, restoring full spermatogenesis in an acquired azoospermia model, and multiplying the sperm production compared to hormonal treatment in a congenitally azoospermic animal model by six-fold (Kara et al., 2025).
FSH bioactivity can also be increased in a female animal model – by up to a three-fold increase in the number of mature oocytes collected when injected in combination with standard of care, and enabling the collection of as many mature oocytes as in the standard of care (12 injections) when injected just once.
The first stage of our recent phase I clinical study was conducted on 16 men and 16 women healthy volunteers treated with a single injection of 4 ascending doses. Results revealed no side effects and demonstrated the very good safety and tolerability of IGX12 across all administered doses. We are extremely encouraged by these data, which pave the way for the next stage of our Phase 1 clinical trial, in which we are currently evaluating repeated administration of IGX12 in healthy male volunteers, a prerequisite for a potential treatment for male infertility due to the duration of spermatogenesis.
New treatments for male infertility would spare women the long and complicated process of IVF. I believe that biopharmaceuticals will be able to significantly improve the quality of life for millions of couples struggling with infertility by offering effective treatment for both men and women.