Spillover to other diseases
JAK inhibitors – some in oral and some in topical form – are showing efficacy in ongoing research for alopecia areata (AA) and vitiligo as well, Dr. Blauvelt said.
“We’re understanding more about the pathophysiology of these diseases, which historically have been tough diseases for dermatologists to treat,” he said. “The successes in alopecia areata and vitiligo are incredibly exciting actually – it’s very exciting to see hair and pigment coming back. And as we learn more, we should be able to develop [additional] drugs that are more disease targeted than the JAK inhibitors.”
Already, some of the biologics used to treat psoriasis have been studied in patients with hidradenitis suppurativa (HS), a disease in which painful lumps and sometimes tunnels form under the skin, with some success; adalimumab (), a TNF-inhibitor, is now FDA approved for the treatment of moderate-severe HS, and studies are ongoing of IL-17 and IL-23 blockers for the disease.
“The pathophysiology [of HS] is very complex; it’s not nearly as straightforward as psoriasis, and there haven’t been any major breakthroughs yet,” Dr. Blauvelt said. “But the drugs seem to be working better than historical alternatives.”
Regarding AA, Dr. Guttman-Yassky, who is participating in a study of dupilumab for AA, recently found in a retrospective cross-sectional study that patients with the condition are more likely to have atopic comorbidities – asthma, allergic rhinitis, and AD, for instance. “The more comorbid conditions, the greater the risk of developing alopecia areata,” she said. “That could point to a potential pathogenic role of the Th2 axis in the disorder [challenging the traditional view of AA as a singularly Th1-centered disease.] The future will tell.”
Action on rare skin diseases
Both large and small companies have moved into the orphan drug space, investing in research and pursuing orphan drug indications for dermatologic conditions, because “it’s clear now in the marketplace that companies can develop effective drugs for rare disorders and be quite successful,” Dr. Orlow said.
According to a recent analysis, as a result of incentives for rare disease drug development contained in the Orphan Drug Act, 72 indications have been approved for rare skin disease, skin-related cancers, and hereditary disorders with prominent dermatologic manifestations since the law was passed in 1983 ().
Epidermolysis bullosa (EB) is a good example, he and other sources said, of commercial interests merging with growing knowledge of disease pathogenesis as well as the tools needed to develop new treatments.
Research by dermatology scientists and others over the past 40 years, Dr. Ju explained, shed light on the molecular basis underlying the structure and function of the junction between the epidermis and dermis, including the pivotal role that type VII collagen plays in the normal adhesion of these two layers. Researchers then learned that, in EB, the family of genetic diseases characterized by skin fragility, “dystrophic types are caused by mutations in the gene encoding type VII collagen,” he said.
“Just as the advent of monoclonal antibodies allowed us to start attacking psoriasis and atopic dermatitis in unprecedented ways, the advent of gene therapy allows us to potentially address the fundamental molecular genetic defect of various types of EB,” Dr. Ju said.
While gene therapy is “still in its infancy,” companies have begun using the tools to address EB. One gene therapy in the pipeline – in phase 3 clinical trial testing – involves grafting back into patients with recessive dystrophic EB their skin cells that have been genetically modified to produce a correct (nonmutated) type VII collagen, he said.
Basal cell nevus syndrome, or Gorlin syndrome, a rare disease in which patients develop a multitude of basal cell carcinoma tumors, is another example of a “dermatology first” approach, Dr. Ju said. Research identified a genetic mutation that causes the hedgehog signaling pathway to be inappropriately activated in the disease, and a drug, vismodegib, was developed to inhibit this pathway. The drug was initially approved for patients with metastatic basal cell cancer and types of advanced basal cell cancer, and is now being tested in cancers affecting other organs, he said.
Basal cell cancer “is a huge market, but it was really unrecognized in the past,” Dr. Eaglstein said. “Seeing drugs come to market for basal cell cancer – this wouldn’t have happened [decades ago].”
Dr. Ju has worked in the pharmaceutical industry; all other sources in this story have worked with pharmaceutical manufacturers of treatments that are being developed or have been approved to treat dermatologic diseases mentioned in this story. In addition to Dr. Ju, Dr. Eaglstein and Dr. Orlow are cofounders of the Advancing Innovation in Dermatology group; Dr. Orlow is a member of the program committee for the organization’s dermatology summit conference.