Dr. Ferguson – Can you tell us in a simple manner, and 1-2 sentences, what the take away would be for an average person with hair thinning i.e could a balding cure develop from studying this class of medication?

A balding cure involving the hedgehog pathway has already been investigated in the past! In 2005-7, Curis, a startup funded by Procter and Gamble worked on a hedgehog pathway agonist drug which was aimed at encouraging hair growth. Mouse model studies gave some encouraging results, but the project was pulled in 2007 because of concerns regarding the drug’s safety profile. The exact nature of these concerns is unclear.

In spite of this it seems possible that drugs affecting the hedgehog pathway could be a potential avenue for development of treatments for hair loss in the future.

How often do you do scalp biopsies on patients with this type of hair loss?

A patient taking vismodegib who develops diffuse, non scarring alopecia of the sort described in our correspondence probably does not need scalp biopsies. However if there is any suspicion of a different cause for the alopecia or the patient has specific concerns it may be helpful.

Does this hair loss have certain specific clinical or histological markers?

In a hedgehog antagonist study performed on mice by Biogen in 2000, specific immunohistochemical tests were developed to show the binding of hedgehog antagonist molecules to hair follicles. As far as i am aware this hasnt been replicated in humans, and is not commercially available. Although we didnt specifically ask! If it were available and worked for human hedgehog antagonist molecules it would be interesting to see if it bound to any of the follicles in our patients’ biopsies!.

Is this a reversible hair loss or does it have a treatment, and does the timeline of treatment/intervention make a difference i.e sooner is better?

On one of our patients oral minoxidil was tried to see if this might help improve hair growth. It made no difference. One patient stopped the medicine and they experienced good regrowth as described in the article. This finding correlates with hedgehog antagonist studies in mice that showed regrowth when the drugs were withdrawn.

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