Dr. Raquel Amaro Silva
SURGEON PONTEVEDRA
Collegiate No. 362607457
Graduated in Medicine and Surgery from the University of Santiago de Compostela with a Master's Degree in Aesthetic Medicine and Trichology and Hair Micrograft. She currently works as a doctor and hair surgeon in Hospital Capilar as head of the headquarters Hospital Capilar Pontevedra.
PP405 is an experimental treatment for the androgenetic alopeciawhich has sparked considerable interest. The reason is simple: it proposes a completely different mechanism of action than traditional treatments. Instead of acting on hormones, it seeks to reverse the miniaturization of the hair follicle through a metabolic mechanism.
In this article you will discover what it is, how it works, what results it has achieved so far, and when it might be available.
PP405 is a topical molecule developed by the biotechnology company Pelage Pharmaceuticals, based on research conducted at the University of California, Los Angeles (UCLA) on the metabolism of hair follicle stem cells and their role in hair regeneration.
Unlike other traditional hair loss treatments, PP405 does not act on DHT or at a hormonal level. Its aim is to stimulate the activity of follicle stem cells to encourage dormant follicles to re-enter the growth phase.
This innovative approach has sparked interest from the scientific community and investors. In October 2025, Pelage Pharmaceuticals closed a $120 million Series B funding round, with participation from Google Ventures (GV) and other biotechnology-focused funds.
However, it's important to remember that PP405 is still an experimental compound. It is currently in clinical trials and is not approved for medical use.
The main differentiating aspect of PP405 is its mechanism of actionInstead of blocking the hormones responsible for androgenetic alopecia, try reactivate the stem cells of the hair follicle by temporarily modifying their energy metabolism.
However, to understand how it works, it is first helpful to know in a simple way how hair grows.
Each hair follicle goes through a continuous cycle consisting of three main phases:
In androgenetic alopecia, this cycle is progressively disrupted. The growth phase is shortened, the hair becomes increasingly thinner, and the follicle eventually miniaturizes until it dies.
PP405 acts on miniaturization to prevent it from disappearing.
PP405 blocks the mitochondrial pyruvate transporter (MPC). This transporter is responsible for bringing pyruvate into the mitochondria so the cell can produce energy. When PP405 temporarily inhibits this process, the cell is forced to use a different metabolic pathway.
Unable to access the mitochondria, pyruvate is diverted to lactate production. Lactate is not only a metabolic product; it also acts as a cell signaling molecule. In the hair follicle, this increase in lactate has been linked to the activation of resting stem cells.
LThe hypothesis behind PP405 suggests that this increase in lactate acts as a chemical signal capable of "waking up" the stem cells of the hair follicle. When this occurs, some follicles that were in the telogen phase could re-enter the anagen phase, initiating a new hair growth cycle.
In other words, PP405 does not create new follicles, but attempts to reactivate follicles that still exist but whose activity is stopped.
PP405 continues in clinical developmentTherefore, it cannot yet be considered an approved treatment for androgenetic alopecia. To date, Pelage Pharmaceuticals has completed trials of 1 phase and a study of 2 phase, whose main objective was to evaluate the safety of the compound and obtain the first data on its possible effectiveness.
In this test Seventy-eight men and women with androgenetic alopecia participated in the study, applying either PP405 or a placebo to their scalp once daily for four weeks. The researchers then followed up until week 12.
Although the primary objective of the study was to evaluate the safety of the treatment, the company reported some data related to hair growth. The most notable finding was that 31% of men with the most severe alopecia experienced an increase in hair density of over 20% by week 8, while no comparable improvements were observed in the placebo group.
These data have sparked considerable interest within the scientific community because they suggest that PP405 may be able to reactivate dormant follicles. However, it is important to interpret these data with caution for several reasons:
Therefore, although the initial results are promising, it will still be necessary to wait for larger studies to confirm the true potential of PP405.
One of the most common questions about PP405 is whether it can restore hair in areas where there is no visible hair.
According to information released by Pelage Pharmaceuticals, the treatment has managed to stimulate the growth of new hair from previously dormant follicular units, that is, follicles that did not produce visible hair but were still viable.
However, this does not mean that PP405 can create new hair or recover completely bald areas.
In androgenetic alopecia, the hair follicle undergoes a progressive miniaturization process until it stops producing hair. As long as the follicle remains viable, there is a possibility that it can be reactivated. It is precisely on these follicles that PP405 aims to act.
However, when the follicle has completely disappeared, no medical treatment has proven capable of regenerating it.
The interest generated by PP405 has led many people to wonder if it could replace established treatments such as finasteride or minoxidil. The answer, for the moment, is No..
Although PP405 has an innovative mechanism of action, it remains an experimental treatment. In contrast, finasteride and minoxidil have widely demonstrated efficacy and are among the standard treatments for androgenetic alopecia.
The main difference between them lies in their mechanism of action
| PP405 | Finasteride | Minoxidil |
Mechanism of action | It inhibits the mitochondrial pyruvate transporter (MPC) and modifies follicle metabolism | It inhibits the 5-alpha reductase enzyme and reduces DHT | It prolongs the anagen phase and promotes hair growth |
Route of administration | Topical | Oral | Oral or topical |
Does it affect hormones? | No | Yes | No |
Approval status | In clinical research | Approved treatment | Approved treatment |
In summary, PP405 does not currently compete with traditional hair loss treatments such as finasteride or minoxidil. If the results of the next phases confirm its efficacy and safety, it could become a new therapeutic option in the future or even be part of combination therapy strategies.
Although it is still too early to define which patients will obtain better results, its mechanism of action allows us to identify some profiles for whom it could become an option of interest:
It's also important to maintain realistic expectations. Reactivating a miniaturized follicle is not the same as recovering a follicle that has already disappeared. When the follicle ceases to be viable and hair loss is irreversible, the FUE hair transplantIt remains the only alternative for restoring hair density.
Currently, PP405 is not approved, so it cannot be purchased or administered outside of authorized clinical trials.
Pelage Pharmaceuticals has announced its intention to begin phase 3 trials in 2026. If the results confirm its efficacy and safety and it passes the regulatory evaluation process, approval could come between the end of 2027 and 2029, although these dates are only an estimate.
Meanwhile, it's important to remember that androgenetic alopecia continues to progress. Waiting several years for an experimental treatment can lead to the loss of hair follicles that may not be able to recover.
For this reason, specialists recommend early diagnosis and an evaluation of currently available treatments. Today, there are proven effective options for slowing the progression of alopecia and improving hair density when started early.
Discover the medical treatments that can stop hair loss and restore hair density today.
No. PP405 is not a cure for baldness. It is an experimental treatment under investigation whose objective is to reactivate follicles in the miniaturization phase.
Initial studies show a favorable safety profile. However, the data are limited, and its long-term safety will need to be confirmed in subsequent phases.
No. PP405 is not currently authorized for commercialization and cannot be purchased in pharmacies, hair clinics, or online sales platforms. Its use is limited exclusively to clinical trials authorized and supervised by the relevant regulatory bodies.
No. It can help with viable follicles, but when the follicle has completely disappeared, FUE hair transplantation remains the only effective option. Therefore, the most recommended treatment will always depend on the degree of alopecia, the progression of each case, and the assessment performed by a specialist.
Currently, it cannot be stated that PP405 will replace established treatments for alopecia. There are no comparative studies or peer-reviewed publications that allow us to determine whether PP405 is more effective than finasteride or dutasteride. If it is ultimately approved, it could be used as an alternative or as a complementary treatment, but we will need to wait for the results of upcoming clinical trials.
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