In 2025 and 2026, several non-hormonal mechanisms have moved into or advanced through human clinical trials. PP405 hair growth research, alongside parallel work on ET-02 and AMP-303, reflects three distinct biological pathways, none of them involving androgen suppression.
This article explains what the current trial evidence actually shows, where each compound stands in development, and how investigational treatments fit alongside options that are available right now.
One clarification up front: “promising trial data” is not the same as an approved treatment. Phase 2 results are encouraging when they’re positive, but they are not proof of efficacy or safety at the population level. This article makes this distinction throughout.
Key takeaways
Why Non-Hormonal Mechanisms Matter
DHT-blocking works by reducing the concentration of dihydrotestosterone at the follicle, the androgen responsible for miniaturizing genetically susceptible hairs. [1] The mechanism is well-understood, and decades of clinical data support its effectiveness.
The problem is systemic: finasteride and dutasteride act throughout the body, not just at the scalp, which is why sexual side effects and hormonal disruption are documented adverse events rather than theoretical risks.
Researchers are exploring alternative pathways based on a simple idea: if hair follicle cycling can be influenced through non-androgenic mechanisms, the systemic hormonal burden can be avoided entirely.
The pathways currently drawing the most clinical attention include:
These pathways are now being investigated in multiple case studies. Several have reached human trials with enough early signal to justify continued investment. Whether any of these approaches will become approved treatments remains uncertain.
Why Hair Loss Is Showing Up Earlier
PP405: Wnt Pathway Activation
PP405, developed by Pelage Pharmaceuticals, is one of the most discussed non-hormonal hair loss candidates in current trials. It is a topically applied small molecule being investigated for its potential to activate the Wnt/β-catenin signaling pathway.
To understand its potential, it helps look briefly at how hair follicles function:
PP405 is being developed to reactivate dormant follicles that remain present, apparently through metabolic stem-cell signaling rather than by creating new follicles or directly targeting hormones. [4]
In its Phase 2a trial, PP405 was applied topically once daily. Effectiveness data published in June 2025 reported statistically significant improvements in total hair count and hair thickness versus placebo, notably, 31% of men with advanced hair loss experienced a hair density increase of 20% or more at the 8-week follow-up point after just 4 weeks of treatment, while none of the placebo group showed comparable improvement. For context, established treatments like minoxidil and finasteride typically require months before any visible difference appears. [4]
The effect was more pronounced in men with earlier-stage androgenetic alopecia, which aligns with the mechanism, follicles that are miniaturized but not yet lost are more likely to respond to reactivation signals than follicles that have been absent for years. Pelage Pharmaceuticals presented additional Phase 2a data at the American Academy of Dermatology Annual Meeting in March 2026, though open-label extension results were not disclosed at that time. [4]
ET-02: Topical Adenosine Receptor Agonism
The adenosine pathway’s relevance to hair growth has been explored for over a decade, and topical adenosine has been used in cosmetic formulations in some markets, but ET-02 involves a more targeted pharmaceutical approach through selective receptor agonism.
ET-02 appears to work by reactivating dysfunctional hair follicle stem cells, rather than by lowering DHT or directly stimulating hormones. The proposed mechanism centers on anagen phase prolongation.
- According to Eirion Therapeutics, androgenic alopecia involves a defect that develops in follicle stem cell biology, causing those cells to become inactive. ET-02 is proposed to correct that defect and restore normal hair growth activity.
- Because it targets stem cell function rather than androgen pathways, it is not expected to carry the sexual side effects associated with finasteride and similar treatments.
In a double-blind, placebo-controlled first-in-man study (N=24), subjects treated once daily with 5% ET-02 for four weeks showed a sixfold increase in non-vellus hair count versus placebo at the five-week mark, alongside an approximately 10-percentage-point improvement in hair width. [5]
Eirion also reported that after one month of treatment, 5% ET-02 produced more non-vellus hair growth than topical minoxidil achieved after four months, based on a separate minoxidil trial (N=180), a striking early comparison, though one that should be interpreted cautiously given the indirect nature of cross-trial benchmarking. [5]
The compound also carries a practical advantage over minoxidil in its once-daily dosing versus minoxidil’s twice-daily regimen.
AMP-303 is an early-stage intradermal hair-loss candidate from Amplifica with first-in-human data reported in 2025. The program is based on research into SCUBE3, a dermal papilla–derived signal identified in Developmental Cell as capable of activating dormant hair follicles in preclinical models and human follicle systems. [6]
As of mid-2026, AMP-303 is in early human development, with first-in-human data reported by Amplifica. Because SCUBE3 is part of a niche-signaling axis distinct from DHT suppression, it may eventually prove complementary to existing approaches, but that remains to be established in controlled human trials
Two additional candidates worth brief mention:
The Honest Summary
The pipeline for non-hormonal hair loss treatment is more active in 2026 than at any prior point. Multiple distinct mechanisms are under investigation simultaneously: stem cell reactivation, Wnt pathway modulation, prostaglandin signaling, and others, representing a genuine diversification away from the androgen-focused approaches that have dominated the field for decades.
How These Compare To Current Non-Surgical Options at Forhair
The pipeline compounds above are investigational. The treatments available at Forhair today are not.
Forhair’s non-surgical treatments include CRP (Cole PRP), Dr. Cole’s formulation of platelet-rich plasma, and exosome therapy, both of which operate through regenerative mechanisms that differ from the pipeline drugs described above.
CRP (Cole PRP)
Cytokine Rich Plasma is Forhair’s advanced formulation of platelet-rich plasma, derived from the patient’s own blood and injected into the scalp. Unlike standard PRP, CRP uses sonication to burst the platelets and release growth factors directly, increasing serum concentration by five to eight times.
Forhair reports approximately a 50% improvement in hair density, with changes visible as early as two months (internal findings not yet described in literature). Results can last nine to twelve months and can be extended by combining CRP with ReyaGel, which can support sustained growth factor activity and may stimulate dormant follicular stem cells.
Exosome Therapy
Exosomes are microscopic vesicles that carry proteins, lipids, and RNA between cells, delivering biological signals that early research suggests may support follicle activity and help sustain the growth phase.
A 2024 randomized controlled trial (Nadeem et al.) reported a mean increase of approximately 35 hairs/cm² within twelve weeks [9], and a 2025 systematic review of eleven clinical studies found consistent improvements in hair density and thickness across the literature. [10]
Results are typically first visible around six months and may persist for one to two years. Forhair is also the first clinic to offer tattoo-delivered exosome therapy, combining plant-derived exosomes with dutasteride to improve scalp penetration.
Stem Cell Treatments
Stem cell–derived therapies include both cell-based approaches, such as autologous micrografts, and cell-free approaches using secretome products and cytokines.
A 2024 systematic review in Plastic & Reconstructive Surgery – Global Open evaluated twelve randomized controlled trials and reported consistent density improvements with a favorable safety profile, though outcomes may be temporary and variable. [11]
Individual studies have reported density increases of approximately 25–30% over baseline in early-to-moderate androgenetic alopecia. [12] Forhair also offers stem cell banking, allowing patients to preserve bone marrow–derived stem cells for potential future use as protocols evolve.
Alma TED
Alma TED is an FDA-cleared, needle-free device that uses ultrasound energy and air pressure to drive a proprietary hair care formula up to 4mm into the dermis. The 20–25 minute treatment is painless, requires no downtime, and produces no post-procedure shedding.
It is designed to increase scalp blood flow and stimulate existing follicles to produce thicker, stronger hair. Forhair recommends at least three treatments spaced one month apart and also uses Alma TED as a delivery mechanism for CRP, making the combined protocol entirely needle-free.
Tricopat
Tricopat is a needle-free therapy that delivers amino acids, growth factors, and medications, including minoxidil and dutasteride, into the scalp using iontophoresis, a low-current electrostimulation technique that enhances penetration beyond what topical application can achieve.
Treatment combines mechanical skin tensioning to improve microcirculation with electrostimulation to drive active compounds into the tissue, in sessions of approximately twenty minutes.
Generally, we recommend a minimum of four treatments spaced three weeks apart.
What Patients Should Do Now
Because hair loss is progressive, delaying treatment may allow further follicular miniaturization and reduce future treatment options. PP405, ET-02, and AMP-303 are not available today; waiting for an investigational treatment while doing nothing is not a neutral choice.
The practical question is not “should I wait for something better?” It is “What is the best plan available right now?” That requires an honest assessment of your Norwood stage, donor area quality, how quickly your loss is progressing, and whether surgical or non-surgical intervention is appropriate. Non-hormonal regenerative options exist today and can be started today.
Transplanted hairs are much more resistant to the androgenic sensitivity that drives native hair loss, but surrounding follicles may continue to thin, which is why a long-term plan matters more than any single procedure.
The most useful next step is a clinical evaluation. Dr. Cole and the Forhair team offer free consultations, including video consultations for patients outside of Atlanta and New York.
Science is moving, and the research in this field continues to advance. The best decisions are made on the basis of what exists today.
Frequently Asked Questions
Is PP405, ET-02, or AMP-303 available for treatment right now?
No, because all three are investigational compounds still in clinical trials and have not been approved by the FDA. Anyone considering these options should treat trial results as preliminary rather than as evidence of an approved treatment.
How is a non-hormonal treatment different from finasteride or minoxidil?
Finasteride works by lowering DHT, the hormone responsible for miniaturizing genetically susceptible follicles, which is why it carries a risk of systemic hormonal side effects. Non-hormonal approaches, including the investigational compounds discussed here and treatments like CRP and exosome therapy, act on separate biological pathways, such as Wnt signaling or growth factor delivery, without affecting androgen levels.
What non-surgical options does Forhair offer?
Forhair offers CRP (Cole PRP), exosome therapy, stem cell–derived treatments, Alma TED, and Tricopat, each targeting follicle activity through regenerative or delivery-based mechanisms rather than hormone suppression. These are established parts of Forhair’s current non-surgical protocol, not experimental. A consultation can help determine which of these fits a specific hair loss pattern and stage.
Should I wait for these new treatments instead of starting something now?
Hair loss tends to progress over time, and delaying treatment can allow further follicular miniaturization. Regenerative options such as CRP and exosome therapy are available today and work through mechanisms distinct from the drugs still in trials.
The more useful question is what plan makes sense given your current Norwood stage and donor area, not whether to wait for a compound that may not reach approval for several more years.
Bibliography:
1. Zhang, Yufan, et al. “Transcriptome Analysis Reveals an Inhibitory Effect of Dihydrotestosterone-Treated 2D- and 3D-Cultured Dermal Papilla Cells on Hair Follicle Growth.” Frontiers in Cell and Developmental Biology, vol. 9, 17 Sept. 2021, https://doi.org/10.3389/fcell.2021.724310. Accessed 2 May 2024.
2. Kim, J., Shin, J.Y., Choi, Y., Joo, J.H., Kwack, M.H., Sung, Y., & Kang, N.G. (2024). Hair Thickness Growth Effect of Adenosine Complex in Male-/Female-Patterned Hair Loss via Inhibition of Androgen Receptor Signaling. International Journal of Molecular Sciences, 25. https://www.semanticscholar.org/paper/Hair-Thickness-Growth-Effect-of-Adenosine-Complex-Kim-Shin/c7dee2f0af28306f054af186c634fcd79291f330
3. Van Mater, D. “Transient Activation of Beta -Catenin Signaling in Cutaneous Keratinocytes Is Sufficient to Trigger the Active Growth Phase of the Hair Cycle in Mice.” Genes & Development, vol. 17, no. 10, 15 May 2003, pp. 1219–1224, https://doi.org/10.1101/gad.1076103. Accessed 24 Apr. 2020.
4. Wikipedia Contributors. “PP405.” Wikipedia, Wikimedia Foundation, 18 May 2026. https://en.wikipedia.org/wiki/PP405
5. News, Eirion. “Eirion Therapeutics Announces Potential Breakthrough Treatment for Hair Loss Based on First-In-Man Clinical Tr.” Eirion, 8 Jan. 2025, www.eirionthera.com/single-post/eirion-therapeutics-announces-potential-breakthrough-treatment-for-hair-loss-based-on-first-in-man-c. Accessed 25 June 2026.
6. Liu Y, Guerrero-Juarez CF, Xiao F, Shettigar NU, Ramos R, Kuan CH, Lin YC, de Jesus Martinez Lomeli L, Park JM, Oh JW, Liu R, Lin SJ, Tartaglia M, Yang RB, Yu Z, Nie Q, Li J, Plikus MV. Hedgehog signaling reprograms hair follicle niche fibroblasts to a hyper-activated state. Dev Cell. 2022 Jul 25;57(14):1758-1775.e7. doi: 10.1016/j.devcel.2022.06.005. Epub 2022 Jun 30. PMID: 35777353; PMCID: PMC9344965.
7. DuBois J, Bruce S, Stewart D, Kempers S, Harutunian C, Boodhoo T, Weitzenfeld A, Chang-Lin JE. Setipiprant for Androgenetic Alopecia in Males: Results from a Randomized, Double-Blind, Placebo-Controlled Phase 2a Trial. Clin Cosmet Investig Dermatol. 2021 Oct 15;14:1507-1517. doi: 10.2147/CCID.S319676. PMID: 34703265; PMCID: PMC8526366.
8. Chan-hyuk, Kim. “Olix Proves Hair Loss Drug’s Safety, Tolerability in Australian P1 Study.” KBR, 13 Jan. 2025, www.koreabiomed.com/news/articleView.html?idxno=26294. Accessed 25 June 2026.
9. Nadeem, Dr Hafsa. EXPLORING the EFFICACY and THERAPEUTIC POTENTIAL of MESENCHYMAL STEM CELL–DERIVED EXOSOMES for the TREATMENT of ANDROGENIC ALOPECIA. 29 Aug. 2024, pp. 1752–1760, www.jptcp.com/index.php/jptcp/article/view/7663, https://doi.org/10.53555/59309h86.
10. Al Ameer, M.A., Alnajim, A.T., Al Ameer, A., Alsalman, Z.H., Al Ameer, G.A., Alnajim, S.T., Alghamdi, A., Moideen, R., & Al Hadi, E.M. (2025). Exosomes and Hair Regeneration: A Systematic Review of Clinical Evidence Across Alopecia Types and Exosome Sources. Clinical, Cosmetic and Investigational Dermatology, 18, 2215 – 2227.
11. Gasteratos, Konstantinos, et al. “Autologous Stem Cell-Derived Therapies for Androgenetic Alopecia: A Systematic Review of Randomized Control Trials on Efficacy, Safety, and Outcomes.” Plastic and Reconstructive Surgery – Global Open, vol. 12, no. 2, 1 Feb. 2024, p. e5606, journals.lww.com/prsgo/fulltext/2024/02000/autologous_stem_cell_derived_therapies_for.48.aspx, https://doi.org/10.1097/GOX.0000000000005606.
12. “Follicular Stem Cell Treatments for Hair Restoration | Forhair.” ForHair Hair Transplant Clinic, 23 Apr. 2026, www.forhair.com/stem-cell-treatments/. Accessed 25 June 2026.
