Who Can Benefit the Most from HMI-115: Men, Women, or People in Transition?

Hair loss is not just a cosmetic issue but a deeply personal one, influencing confidence, identity, and social interactions. It affects men, women, and people undergoing gender transition differently. Traditional treatments such as finasteride and minoxidil have remained the main options for decades, but they come with limitations. Minoxidil stimulates blood flow in the scalp without addressing underlying causes, while finasteride reduces dihydrotestosterone (DHT) but carries reported side effects that are not only hormonal or sexual: its label also lists depression and suicidal thoughts and breast and semen changes, and some men report sexual and mood symptoms continuing after stopping, at a frequency that is not known (see the FAQ 'Is finasteride safe?'). In this context, HMI-115 has appeared as a novel therapeutic candidate, raising questions about who might benefit the most.

Understanding HMI-115 and Its Mechanism

HMI-115 is a monoclonal antibody, which means it is a laboratory-made protein designed to target a specific molecule in the body. In this case, the developer describes it as binding to the prolactin receptor and blocking the signal of prolactin, a hormone best known for its role in breastfeeding. It does not lower prolactin itself. Laboratory work reported by the company suggests that prolactin signalling also influences hair follicle cycling. Prolactin signalling at the follicle has been linked in laboratory studies to follicles moving early into a resting phase, where hair sheds or thins. The stated rationale for HMI-115 is therefore that blocking the prolactin receptor in the scalp may allow follicles to return to the active growth phase. That rationale has not yet been confirmed by a published, peer-reviewed human trial.

This mechanism makes HMI-115 distinct from finasteride or minoxidil. It does not manipulate testosterone or DHT directly, nor does it simply increase circulation. Instead, it targets a separate pathway. Whether that pathway matters more in women or in transgender people than in men is a hypothesis discussed by the company and by community members, not a finding from a completed comparison study.

Men and HMI-115: A Complement, Not a Replacement

Male pattern baldness, or androgenetic alopecia, is largely driven by DHT. This hormone gradually shrinks hair follicles until they can no longer produce visible hair. Finasteride reduces DHT levels, while minoxidil stimulates existing follicles, making them grow thicker hair. The key question for men is whether HMI-115 offers additional benefit beyond these treatments.

The only human efficacy data released so far comes from an open-label Phase 1b study run in Australia and led by Professor Rodney Sinclair, which treated 12 men and 4 women with androgenic alopecia over 24 weeks. Hope Medicine announced the outcome in a company press release in January 2024: in the 12 men, the mean non-vellus target area hair count rose by 14 hairs per square centimetre against baseline, and the company described the antibody as safe and well tolerated at the doses studied. These figures come from a press release, not from a peer-reviewed paper, and the study had no placebo arm and no comparison against finasteride or minoxidil. No trial has compared HMI-115 head-to-head with an established treatment, so nothing published supports either replacing or adding to finasteride and minoxidil. For men, the early signal is unconfirmed.

Women and HMI-115: A Different Hormonal Story

Female pattern hair loss (FPHL) does not always follow the same DHT-driven pathway as male pattern baldness. Many women experience hair thinning linked to hormonal changes such as pregnancy, menopause, or stress, and prolactin is one of the hormones that shifts during those changes. Anti-DHT drugs like finasteride often show limited success in women, underlining the interest in alternative approaches. Finasteride is not approved for hair loss in women, and it must not be used by anyone who is or may become pregnant, because it can harm a male fetus.

There is, however, no published trial of HMI-115 in women with hair loss. The Australian Phase 1b study did include 4 women, but the company did not release their results. The idea that women stand to benefit most from HMI-115 is an argument from mechanism, not a measured result. Hope Medicine has also developed the same antibody for endometriosis, which is why the drug is often discussed as relevant to women, but a programme in a different disease is not evidence of hair regrowth in women.

People in Transition: Special Considerations

For transgender individuals, hair is often deeply tied to identity and gender expression. Hormone therapy can have unintended effects on scalp hair. Trans women, for example, may still face androgenetic alopecia from years of androgen exposure before starting estrogen therapy. Trans men may see new hair thinning due to testosterone-induced increases in DHT. Because HMI-115 targets the prolactin receptor rather than testosterone or DHT, community discussion often assumes it would sit comfortably alongside gender-affirming hormone therapy. No study has tested HMI-115 together with estradiol, testosterone, or an anti-androgen, so no interaction claim can be made in either direction. Prolactin itself is affected by estrogen therapy, which is a further reason the combination would need to be studied rather than assumed. There are no published case series in transgender patients, and the drug is not obtainable outside company-run trials.

A Critical View: Who Gains the Most?

The published human evidence is limited to one small, open-label, company-reported Phase 1b study, and that study reported results for men only. On that basis, no group can be identified as the one that benefits most. The mechanistic argument for women and for transgender people is reasonable and untested. For men, the reported hair-count increase is real data but comes without a control group. Until placebo-controlled trials report in each population, the position of HMI-115 in the treatment landscape remains uncertain.

HMI-115 is an experimental injectable antibody. It is not an approved medicine anywhere, it cannot be obtained outside a clinical trial, and its long-term safety is unknown. Talk to a doctor or pharmacist before starting, stopping or combining any hair-loss treatment, and especially before adding an investigational drug to hormone therapy.

Research Section

The Australian Phase 1b study is the source of every human efficacy number quoted for HMI-115. It was open-label, enrolled 12 men and 4 women with androgenic alopecia, and ran for 24 weeks under Professor Rodney Sinclair. The company reported a mean increase of 14 non-vellus hairs per square centimetre in the men and described the drug as safe and well tolerated. The limitations are the small population, the open-label design without a placebo group, the absence of released data for the four women, and the fact that the results were announced by press release rather than published.

Hope Medicine has since run a larger placebo-controlled Phase 2 study in androgenetic alopecia in China (NCT06118866), which enrolled 192 participants over 24 weeks and is registered as completed, and has announced US FDA clearance for a Phase II trial. That Phase 2 study enrolled men only, and no peer-reviewed results have been published, so any claim about which group responds best is still waiting on data that has not been collected.

Taken together, HMI-115 remains experimental. Men have the only released efficacy numbers; women and transgender people have a mechanistic rationale and no published outcomes. What would settle the question is larger, controlled, long-term studies reporting results separately for each group.

User Experiences

The discussion around HMI-115 within the Tressless community highlights both optimism and caution. As an investigational drug targeting the prolactin receptor, HMI-115 stands apart from the usual DHT-blocking strategies. Because it acts on a different pathway, many users are curious whether it might help groups underserved by current treatments—particularly women and individuals in transition.

Community members note that HMI-115 is still in clinical trials, with studies ongoing in China and Australia. Users have shared leaked images and early reports describing visible thickening within about two months, and these are unverified user posts rather than trial data. Some users emphasize that unlike finasteride or dutasteride, which mainly address androgen-driven baldness in men, HMI-115's prolactin-receptor blocking mechanism might make it relevant for women and trans people whose hair loss involves different hormonal interactions. At the same time, skepticism is strong. Many point to past disappointments with other much-hyped compounds such as cosmeRNA, Breezula, and pyrilutamide. Users express concern that early trial photos may not translate into long-term, reliable outcomes. There is also awareness that HMI-115, as a monoclonal antibody therapy, will likely be expensive and difficult to access outside clinical trials, making it less comparable to established, affordable treatments like minoxidil or finasteride.

One recurring theme is safety and applicability across sexes. Since HMI-115 is also being studied for endometriosis, several users argue that its dual focus indicates it could benefit women as well as men. Trans participants in the discussion are cautiously hopeful, suggesting that because prolactin and its receptor play roles across different hormonal environments, this drug might open the door for more inclusive hair restoration strategies. Still, without long-term data, most agree that it is too early to declare which group—men, women, or people in transition—will benefit the most. In summary, the community sees HMI-115 as promising but unproven. Its novel mechanism brings optimism for broader applicability, but members remain realistic about the long road from early trial results to a safe, effective, and widely available treatment.

References

Hope Medicine. (2024, January 15). Positive Outcome from a Phase Ib Study in Australia Treating Patients with Androgenic Alopecia. Retrieved from https://www.hopemedinc.com/company-release-37

ClinicalTrials.gov. Phase 2 study of HMI-115 in male androgenetic alopecia over a 24-week treatment period (NCT06118866). https://clinicaltrials.gov/study/NCT06118866

Hope Medicine. Announces US FDA Clearance for Phase II Clinical Trial of A First-in-class Monoclonal Antibody, HMI-115, in AGA Alopecia. Retrieved from https://www.hopemedinc.com/company-release-5

Tressless Community. (2024, June 19). Is hmi 115 the cure? Or is it just like cosmeRNA, brezula, pyrilutamide, and others. Retrieved from https://reddit.com/r/tressless/comments/1djrrpd/is_hmi_115_the_cure_or_is_it_just_like_cosmerna/

Tressless Community. (2024, May 27). HMI-115: What We Know So Far. HMI-115 (also known as BAY1158061) is a new pharmaceutical drug developed by a biopharmaceutical company called Bioinvent and licensed by Bayer. Retrieved from https://reddit.com/r/tressless/comments/1d1tffj/hmi115_what_we_know_so_far_hmi115_also_known_as/

Tressless Community. (2024, May 16). 2-month HMI-115 results from the Chinese trial. Retrieved from https://reddit.com/r/tressless/comments/1ctjjfy/2month_hmi115_results_from_the_chinese_trial/

Tressless Community. (2024, May 3). HMI 115 Phase 2 - Leaked pics from Discord. Retrieved from https://reddit.com/r/tressless/comments/1cj63dg/hmi_115_phase_2_leaked_pics_from_discord/

Tressless Community. (2023, October 28). HMI-115 update: Chime Biologics and Hope Medicine Enter Manufacturing Agreement to Speed up the Launch of First-in-class Antibody Drug HMI-115 Targeting Endometriosis and Androgenic Alopecia. Retrieved from https://reddit.com/r/tressless/comments/17i1w6t/hmi115_update_chime_biologics_and_hope_medicine/

Tressless Community. (2023, October 18). HMI-115 Australian Phase 1 Trial completed?. Retrieved from https://reddit.com/r/tressless/comments/17ag1x6/hmi115_australian_phase_1_trial_completed/

Tressless Community. (2023, October 6). HMI-115 trials in China - How to participate?. Retrieved from https://reddit.com/r/tressless/comments/1719vor/hmi115_trials_in_china_how_to_participate/

Tressless Community. (2023, September 19). HMI-115 start AGA phase 2 trial volunteer in China. The eligible volunteer should be age between 18 to 65, Norwood 3 vertex , 4 and 5. And agree to prevent pregnancy. Retrieved from https://reddit.com/r/tressless/comments/16mmy0z/hmi115_start_aga_phase_2_trial_volunteer_in_china/

Tressless Community. (2023, June 29). What do we actually know about HMI-115?. Retrieved from https://reddit.com/r/tressless/comments/14m8cr2/what_do_we_actually_know_about_hmi115/

Tressless Community. (2023, April 15). HMI-115 question about potential earliest access. Retrieved from https://reddit.com/r/tressless/comments/12nelu3/hmi115_question_about_potential_earliest_access/

Propecia (finasteride) prescribing information, Organon. DailyMed. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=6f904709-65aa-44ce-b144-b4c8a0416e36

Medicines and Healthcare products Regulatory Agency. (2026, May 11). Finasteride and dutasteride: updated safety warnings for psychiatric side effects and sexual dysfunction. Drug Safety Update. https://www.gov.uk/drug-safety-update/finasteride-and-dutasteride-updated-safety-warnings-for-psychiatric-side-effects-and-sexual-dysfunction