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A new clinical practice guideline will be available thanks to new treatment options including oral AGA agents

The mechanism behind hair loss has been elucidated thanks to progress in molecular biology in recent years and thus an avenue of treatment for thinning hair has been provided. Five years have passed since the "Clinical Practice Guideline for Androgenic Alopecia" and the "Clinical Practice Guideline for Alopecia Areata" have been published in 2010. Now, the 2nd edition of evidence-based guideline is in the process of revising (scheduled to be published in 2017). I asked Professor Satoshi Itami, a leading authority on hair science, about the cutting-edge hair loss treatments.

Why is your hair falling out?

The basic mechanism behind hair loss has been elucidated substantially thanks to progress in molecular biology in recent years, which has occurred in the past decade. As Professor Satoshi Itami explained the mechanism behind hair loss in detail in “Aderans Plus” Vol.1, we start this article by reviewing it.

Human hair grows between 2 to 6 years on average, repeating hair cycles: a growth phase (anagen phase), a transitional phase (catagen phase) and a resting phase (telogen phase). If the growth phase shortens because of disruption of this hair cycle and so on, the hair will fall out before it fully grows leading to thinning hair on the front or on the side on the head. This is what androgenic alopecia is all about. Androgenic hormone called as testosterone is known to be greatly associated with androgenic alopecia. When testosterone flows through the bloodstream and enters dermal papilla cells which inhibit hair growth, it is converted into a more potent androgenic hormone called as dihydrotestosterone (DHT) by actions of 5-alpha reductase. The DHT enters in the nucleus of dermal papilla cells by binding to androgen receptors in the cell and binds to target gene promoters. Then, the DHT releases signals that cause beard growth while it sends signals that inhibit hair growth to the front or the top of the head, leading to the thinning hair on the areas. This is how androgenic alopecia proceeds.

That is why a medication called as “finasteride” as a drug indicated for the treatment of androgenic alopecia has been developed. The drug is designed to block growth inhibitory signals released from androgenic hormone. The drug is now commercially available under the product name of “Propecia” in Japan. There is a clinical study result showing that after three years of treatment, 80% of men taking finasteride experienced a “slight increase of hair volume”.

AGA medications, finasteride and dutasteride

What features does finasteride have?

Finasteride was originally developed for the treatment of benign prostate hypertrophy. 5-alpha reductase which is a causative agent for androgenic alopecia occurs as 2 isozymes, type 1 and type 2. Especially, 5-alpha reductase type 2 which resides in dermal papilla cells is associated with production of DHT causing hair loss. Finasteride blocks binding of testosterone and 5-alpha reductase type 2, resulting in a decrease in the expression level of type 2 DHT.

Dutasteride with the same actions as finasteride has attracted attention recently.

Dutasteride is also used for the treatment of benign prostate hypertrophy. A drug is eliminated from the body in several hours after taking it. Dutasteride remains in the body longer than finasteride. Also, dutasteride is said to exert its effects earlier. In fact, clinical studies are now underway in various countries including South Korea and Japan. I hear that in a 6-month clinical study, the similar results as those of finasteride have been shown. Cheaper drugs are sold online, which does not ensure the safety of these drugs.

I hear that dutasteride is used for the treatment of androgenic alopecia which medical expenses are not covered by insurance in South Korea. Do you think dutasteride will be able to be used by physician’s prescription?

Generally, it is difficult to decide whether to use a drug unless you obtain the results from one year or so study. However, if finasteride is not effective in a patient taking the drug for 1 year, the patient may ask a trusted physician to prescribe dutasteride. I think this type of treatment option may be useful for the patient.

Is there a treatment option which switches finasteride to dutasteride?

It is not allowed, because any adverse effect may occur. For example, finasteride 1 mg is sufficient to exert its effect. Even if you take five times the amount of the drug, its effects are the same. On the contrary, it may cause adverse effects.

Is there a treatment option which switches finasteride to dutasteride?

As the efficacy of finasteride has been established to some extent, I think there is no option of switching to dutasteride in patients taking finasteride for several years and who feel that it is effective. In my opinion, potential patients who use dutasteride are newly diagnosed, untreated patients.

Expect hair restoration as well as development of new clinical practice guideline

The Japanese Dermatological Association published the “Clinical Practice Guideline for Androgenic Alopecia” and the “Clinical Practice Guideline for alopecia areata” in 2010. When will new clinical practice guideline be published?

its first publication. As novel mechanisms behind the disease have been found for the last 5 to 6 years, it is necessary to add them. Moreover, new therapeutic approaches are available. It is about time to revise it. Then, we are in the process of looking for members in charge of revising it. The procedure for revision will be completed by the end of 2016. We plan to publish the newly revised clinical practice guideline in 2017.

What measures do you employ in formulating the guideline?

The measures we employ are how many evidence-based articles there are regarding each drug or treatment. It is not that the guideline is decided based on the opinion of an authority. On the contrary, an expert opinion is the lowest level of acceptable evidence.

Does it mean that evidence obtained from clinical studies is put the highest value on?

Yes, it does. However, only single evidence is not reliable enough. By collecting as many articles on clinical studies with high level of evidence as possible and by critically appraising them, it can be accepted as the most reliable evidence of whether a treatment is effective. Specifically, a study with the highest level of evidence is that both physicians and participants are blind to the nature of the treatment the participant is receiving (double blind) and patients are randomly assigned either to placebo (an inactive substance used as a control) or active drug for a given period of time in order to compare the efficacy and safety of a drug. Outcome assessors are subject to bias without using this approach. Taking an example of patients, just thinking that an active drug is given, patients may feel as if it works (placebo effect). Thus, it is necessary to conduct a double-blind study in which both the subjects and the researchers are unaware of which the experimental medication has been given and moreover patient background including age and disease progression must be similar between two groups.

Both finasteride and minoxidil have been evaluated based on evidence from such double-blind studies.

Thanks to the clinical practice guidelines, patients who wish treatment can receive the one with high level of evidence, can’t they?

If the guidelines can show what treatments should be given, when an individual who wishes to receive treatment for thinning hair goes to see as physician, a healthcare professional can recommend “evidence-based treatment” with confidence. Also, the guidelines will serve as a useful reference for individual people in choosing a hospital, clinic, pharmacy or hair growth product.

Finally, I believe what people have the highest hope for is hair restoration. What is its current situation?

Itami A research in which cells are extracted from the skin and cultivated for restoring hair follicles and dermal papilla is underway. However, 90% of genes capable of inducing hair follicles and dermal papilla begin sleeping once cells are separated from body and proliferated on the plate. It is a challenge to find how to awaken sleeping genes (cells). A foreign study reports a successful case. However, it will take a long time to put it into practical use because there are various obstacles ahead.

Interviewer/writer: Akiyoshi Sato Photographer: Naoyuki Tamura

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