Topical rapamycin as a treatment for fibrofolliculomas in Birt-Hogg-Dubé syndrome:a double-blind placebo-controlled randomized split-face trial

Background: Birt-Hogg-Dubé syndrome (BHD) is a rare autosomal dominant disorder characterised by the occurrence of benign, mostly facial, skin tumours called fibrofolliculomas, multiple lung cysts, spontaneous pneumothorax and an increased renal cancer risk. Current treatments for fibrofolliculomas have high rates of recurrence and carry a risk of complications. It would be desirable to have a treatment that could prevent fibrofolliculomas from growing. Animal models of BHD have previously shown deregulation of mammalian target of rapamycin (mTOR). Topical use of the mTOR inhibitor rapamycin is an effective treatment for the skin tumours (angiofibromas) in tuberous sclerosis complex, which is also characterised by mTOR deregulation. In this study we aimed to determine if topical rapamycin is also an effective treatment for fibrofolliculomas in BHD. Methods: We performed a double blinded, randomised, facial left-right controlled trial of topical rapamycin 0.1% versus placebo in 19 BHD patients. Trial duration was 6 months. The primary outcome was cosmetic improvement as measured by doctors and patients. Changes in fibrofolliculoma number and size were also measured, as was occurrence of side effects. Results: No change in cosmetic status of fibrofolliculomas was reported in the majority of cases for the rapamycin treated (79% by doctors, 53% by patients) as well as the placebo treated facial sides (both 74%). No significant differences between rapamycin and placebo treated facial halves were observed (p = 1.000 for doctors opinion, p = 0.344 for patients opinion). No significant difference in fibrofolliculoma number or change in size of the fibrofolliculomas was seen after 6 months. Side effects occurred more often after rapamycin treatment (68% of patients) than after placebo (58% of patients; p = 0.625). A burning sensation, erythema, itching and dryness were most frequently reported. Conclusions: This study provides no evidence that treatment of fibrofolliculomas with topical rapamycin in BHD results in cosmetic improvement. Trial Registration: ClinicalTrials.gov NCT00928798</p

Birt-Hogg-Dubé syndrome: from patient to protein

Patients suffering from a rare genetic disease called Birt-Hogg-Dubé (BHD) syndrome are at increased risk of developing benign facial papules (fibrofolliculomas), lung cysts, pneumothorax and kidney cancer. In the clinic, we focus on the early detection of kidney cancer by making a kidney scan. This approach enables us to treat kidney cancer at an early stage. However, only few patients are actually undergoing this test. In this dissertation, we offer suggestions on how to increase patient participation. We have also tested a potential treatment for fibrofolliculomas. Unfortunately, this was shown not to be effective. The BHD syndrome is caused by an alteration in the FLCN gene, the function of which remains unknown. We have shown that the protein is located in the cilium, the cellular antenna. This may explain the formation of cysts and perhaps also the formation of tumours. Further research into the function of FLCN is needed to develop a targeted (preventive) treatment for patients with BHD syndrome

What's new in Birt-Hogg-Dubé syndrome?

Birt-Hogg-Dubé syndrome (BHD) is a rare inherited condition, which predisposes to the development of benign hair follicle tumors called fibrofolliculomas, pneumothorax and kidney cancer. Lung and kidney cysts, respectively, are thought to cause the latter symptoms. The causative gene codes for a highly conserved protein called folliculin. Its function is still unknown, although recent data hint at a pervasive function in cellular signaling, affecting hypoxia responses and growth pathways. Because folliculin's role in the cell is unclear, BHD symptoms are not well understood. Treatment, therefore, is still empirical. In this review, the authors summarize the current state of knowledge and report some of the most recent findings. The authors discuss the implications for pathogenesis and treatment of the cutaneous manifestations in BHD

Birt-Hogg-Dubé syndrome and the skin

Birt-Hogg-Dubé syndrome (MIM #135150) is characterized by the development of benign skin tumours called fibrofolliculomas, pulmonary cysts that may lead to pneumothorax and a high risk of developing kidney cancer. BHD is caused by mutations affecting the highly conserved protein folliculin (FLCN), which probably has a role in intracellular transport. Most of the research effort directed towards BHD has focused on understanding how loss of FLCN causes kidney cancer. The cutaneous manifestations have received comparatively little attention. Although understandable, it is unfortunate, as the fibrofolliculomas are highly accessible and thus potentially are an excellent system for trying to understand the basic pathobiology of BHD. Also, patients can be very much burdened by the cosmetic consequences of having hundreds of facial skin tumours. Our lack of insight into what drives fibrofolliculoma growth translates into a very limited therapeutic arsenal. Thus, paying attention to fibrofolliculomas has both basic science and practical benefits. In this review, we will discuss the state of the art regarding our understanding of fibrofolliculoma pathogenesis and indicate future directions for research

Transgenic mouse technology in skin biology: generation of complete or tissue-specific knockout mice

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Familial Pityriasis Rubra Pilaris Is Caused by Mutations in CARD14

Pityriasis rubra pilaris (PRP) is a papulosquamous disorder phenotypically related to psoriasis. The disease has been occasionally shown to be inherited in an autosomal-dominant fashion. To identify the genetic cause of familial PRP, we ascertained four unrelated families affected by autosomal-dominant PRP. We initially mapped PRP to 17q25.3, a region overlapping with psoriasis susceptibility locus 2 (PSORS2 [MIM 602723]). Using a combination of linkage analysis followed by targeted whole-exome sequencing and candidate-gene screening, we identified three different heterozygous mutations in CARD14, which encodes caspase recruitment domain family, member 14. CARD14 was found to be specifically expressed in the skin. CARD14 is a known activator of nuclear factor kappa B signaling, which has been implicated in inflammatory disorders. Accordingly, CARD14 levels were increased, and p65 was found to be activated in the skin of PRP-affected individuals. The present data demonstrate that autosomal-dominant PRP is allelic to familial psoriasis, which was recently shown to also be caused by mutations in CARD14

Photographic recording of cosmetic status during rapamycin treatment.

<p>Close up of standardised facial photographs taken at baseline, 3 months and 6 months after starting treatment with topical rapamycin or placebo per facial half. Photos of a representative patient are shown, revealing no visible improvement or worsening of the facial fibrofolliculomas.</p

Between-treatment comparison of mean change in fibrofolliculoma size compared to baseline (in mm) using the T-test for paired samples.

<p>SD = standard deviation; CI = confidence interval.</p