Is Hair Loss Treatment Entering an Era of "Awakening Dormant Hair Follicles"? — The New Hair Growth Route Challenged by the Noteworthy Ingredient "PP405"

Every time I look in the mirror, I'm concerned about my hairline and the top of my head. When I come across news about new hair growth ingredients, I feel hopeful, yet I brace myself thinking, "Isn't this just another exaggerated story?"

For those who feel this way, there's a development code you should know about: "PP405."

On September 30, 2026, the German financial information site aktiencheck highlighted research by a U.S. biotech company from the perspective that hair loss treatment could become a promising growth market in the future. The public introduction mentions a molecule that awakens dormant hair follicles and the involvement of GV (formerly Google Ventures).

However, what those awaiting treatment want to know more than the market size is, "What could happen to my hair?"

The novelty of PP405 lies in its focus on the metabolism necessary for hair follicle stem cells to be active.

What is PP405?—Not a cosmetic ingredient, but a drug candidate in development

PP405 is a low-molecular compound developed by the American company Pelage Pharmaceuticals, designed to be applied to the scalp. The foundation of the research is based on stem cell biology and metabolism studies from the University of California, Los Angeles (UCLA).

It's important to distinguish that PP405 is not an already established effective commercial hair growth ingredient. It is an investigational drug being tested for safety and efficacy in humans.

Moreover, when we say "acts on stem cells," it does not involve transplanting stem cells into the scalp. Instead, it aims to alter the function of stem cells already present in hair follicles through the drug molecule.

In an introductory article by UCLA, researchers express their expectations for initial results while explaining that it will not become a product effective for everyone. From the starting point of development, a panacea is not promised.

The key is "how cells use energy"

Hair follicles are small organs that produce hair. Hair follicle stem cells are involved in the cycle of hair growth and rest.

PP405 targets a transporter called "MPC," which carries pyruvate to mitochondria. According to the developer, it is designed to inhibit this function, change cell metabolism, and lead to the reactivation of hair follicle stem cells.

In the underlying basic research at UCLA, the relationship between the metabolic pathway that produces lactic acid and the activity of hair follicle stem cells has been investigated. For cells, which pathway they use to utilize energy can be a clue to switching activity states.

The expression "awakening dormant hair follicles" is a simplified way of explaining this concept.

However, it has not been shown that new hair follicles can be created from scratch anywhere on the scalp. Separate verification is needed to determine whether it can restore the state where hair follicles have been lost or how much it can address long-term hair loss.

How is it different from traditional AGA treatments?

In Japan, finasteride and dutasteride, known for treating male pattern baldness (AGA), act on pathways related to male hormones. Minoxidil topical application also has a track record as a treatment that promotes hair growth.

PP405 targets the metabolism of hair follicle stem cells, which is different from these. Therefore, it is expected as an option that does not directly target hormones.

However, "new mechanism of action" does not mean "more effective than existing drugs." Without trials that directly compare under the same conditions, superiority cannot be judged.

Regarding existing drugs, it is inaccurate to describe them as merely stopping hair loss. Some treatments can be expected to improve hair count and appearance. When understanding PP405, it is necessary to view it as a potential new mechanism of action without underestimating traditional drugs.

What does the much-discussed "31%" mean?

In the Phase 2a trial announced by the developer in June 2025, 78 men and women with male and female pattern baldness participated. PP405 or a placebo was applied once daily for four weeks, with observations up to 12 weeks.

The focus was on the analysis results of men with more advanced hair loss. At eight weeks after the start of administration, 31% of the PP405 group showed an increase in hair density of more than 20%, while 0% met the same criteria in the placebo group.

This result is a promising sign, but it does not mean "the hair of users increased by an average of 31%." Nor does it mean "31% of all participants overcame hair loss."

It is a figure showing the percentage of people in a specific group who exceeded a certain increase criterion.

Moreover, the main purpose of the trial was to confirm safety, and hair growth was an exploratory evaluation. Detailed interpretation of the results also requires considering the number of subjects analyzed, variability, and the persistence of effects.

"Not detected in the blood" is different from "zero side effects"

Regarding the same trial, the developer explained that PP405 was well tolerated and not detected in the blood.

The fact that a drug applied to the scalp was not detected in the body is a positive development factor. However, conclusions about long-term use and rare side effects cannot be drawn from short-term trials.

Similarly, the fact that it does not directly target hormones alone cannot be used to judge that there are no side effects. New drugs require their own safety data.

Verification progresses in 2026—not just "vellus hair," but from which hair follicles it grows

In a presentation for the American Academy of Dermatology Annual Meeting in March 2026, Pelage reported the growth of "terminal hair" from previously dormant hair follicle units. Terminal hair refers to thick, strong hair distinguished from thin, short vellus hair.

The company emphasizes not only the number of hairs but also whether the number of hair follicle units producing hair increases. This serves as a meaningful observation point in verifying the impact on dormant states.

On the other hand, what matters to patients is the extent to which their appearance ultimately changes and how long that state lasts. Both microscopic changes and improvements that can be felt in daily life need to be confirmed.

On ClinicalTrials.gov, the registration of the Phase 2/3 trial "AWAKEN," which examines efficacy and long-term safety in adult men, can be confirmed. Registration of late-stage trials is a step forward, but it does not mean success or marketing approval has been decided.

On social media, expectations and caution intertwine

In the overseas hair loss community on Reddit, "r/tressless," discussions about PP405 continue. The following is a summary of actual public posts and does not represent the opinions of all users.

After the results were announced in June 2025, there were posts expressing strong expectations for changes reported in a short period of administration and the idea of reactivating hair follicles. There is a perception that a different option from the past may emerge.

On the other hand, in discussions in February 2026, there were voices pointing out the small size of the analysis group and the possibility that secondary reports exaggerated the results. In response to the expectation that "it must work because investors are funding it," a perspective that does not confuse fundraising with proof of efficacy is necessary.

Furthermore, in the summer of the same year, there were reports from posters who independently tried research compounds related to PP405, stating they did not feel any effect. However, such self-reports are not comparative trials with the same quality, formulation, and conditions as clinical trials. Neither success stories nor failure stories can be directly concluded as PP405's results.

The enthusiasm on social media indicates the large number of people waiting for new treatments more than the confirmed effects.

When will it be available in Japan?

What concerns Japanese readers is the release timing, cost, and whether they will be eligible.

In the public materials confirmed this time, no information was found to determine the approval and release date or price in Japan. The progress of development overseas and being able to receive prescriptions in Japan are at different stages.

There are also expectations for women, but the efficacy and safety for women cannot be said to be established with only the initial trials involving both men and women. Verification for each target group is essential.

Regarding current hair loss concerns, it is important to confirm the type of hair loss before deciding whether to wait for the practical application of PP405. The Japanese Dermatological Association distinguishes recommended treatments for male and female patterns. It is not the stage to replace current treatments based on self-judgment due to news of new drug candidates.

The future expected by investment money and the results sought by patients

In October 2025, Pelage announced a $120 million Series B funding led jointly by ARCH Venture Partners and GV.

This funding will be a force to advance development. However, it is necessary to distinguish between investors evaluating future potential and sufficient proof of efficacy for patients.

The value of hair loss treatment cannot be measured by the number of hairs alone. It also involves the freedom to choose hairstyles, the feeling when appearing in photos, and the burden of looking in the mirror every morning. That's why expectations for new research are high.

What PP405 indicates is the possibility that there may be a new entry point for hair loss treatment.

What needs to be confirmed next is not "how much it was talked about," but "to whom, how much, and for how long it works." Future clinical trials will gradually reveal the answers to these questions.

Sources and Reference URLs

1. aktiencheck:
   https://www.aktiencheck.de/exklusiv/Artikel-Haarausfall_koennte_zum_spannendsten_Wachstumsmarkt_Jahrzehnts_werden-20133697
   Introduction page:
   https://www.investor-sms.de/haarausfall-koennte-zum-spannendsten-wachstumsmarkt-des-jahrzehnts-werden/investor-sms

2. UCLA: Background of PP405 research and explanations of expectations and limitations by researchers.
   https://newsroom.ucla.edu/magazine/baldness-cure-pp405-molecule-breakthrough-treatmentUCLA

3. UCLA Health: Basic research on lactic acid production and hair follicle stem cell activation.
   Findings from animal experiments, not indicative of effects on humans.
   https://www.uclahealth.org/news/release/ucla-scientists-identify-a-new-way-to-activate-stem-cells-to-make-hair-growUCLA Health

4. Pelage: Explanation of PP405's MPC inhibitory action and Phase 1 trial by the developer.
   https://pelagepharma.com/press-releases/pelage-presents-late-breaking-data-at-aad-2024-meeting-demonstrating-pp405-activates-human-hair-follicle-stem-cells-ex-vivo-and-in-phase-1-clinical-study/Pelage

5. Pelage: Results of the Phase 2a trial.
   Design of the trial with 78 participants, "31%" and "hair density over 20%" in a specific male group, and safety explanation. Treated as a company announcement.
   https://pelagepharma.com/press-releases/pelage-pharmaceuticals-announces-positive-phase-2a-clinical-trial-results-for-pp405-in-regenerative-hair-loss-therapy/Pelage

6. Pelage: Information on the 2026 conference presentation.
   Growth of terminal hair from dormant hair follicle units and policy for late-stage development.
   https://pelagepharma.com/press-releases/pelage-pp405-aad-2026/Pelage

7. ClinicalTrials.gov: Registration of the Phase 2/3 trial AWAKEN targeting adult men.
   The trial registration number is NCT07819435. Registration does not imply efficacy confirmation or marketing approval.
   https://clinicaltrials.gov/study/NCT07819435Clinical Trials

8. Japanese Dermatological Association: Explanation of treatments for male and female pattern baldness in Japan.
   https://qa.dermatol.or.jp/qa11/q07.html
   https://qa.dermatol.or.jp/qa11/q09.html
   Clinical guidelines:
   https://www.jstage.jst.go.jp/article/dermatol/127/13/127_2763/_article/-char/jaDermatology Q&A (Japanese Dermatological Association)##HTML_TAG