According to the results of a recent Yale School of Medicine clinical trial, researchers could be just steps away from finding a cure for alopecia areata, an autoimmune disease that causes partial or complete hair loss.

The study tested the effect of tofacitinib -— an FDA-approved medication for rheumatoid arthritis — on 66 patients suffering from AA, which results from the immune system attacking hair follicles. There is currently no FDA-approved treatment for the condition, and drugs previously used have rarely yielded a positive response. However, the Yale researchers, in collaboration with researchers at Stanford University and Columbia University, reported that more than 60 percent of patients responded positively to the tested drug in the recent clinical trials. The study was published in the Journal of Clinical Investigation on Sept. 22.

“When you look at over 66 patients and you show that one third of patients achieved more than …  50 percent recovery of hair loss from their base line condition, that’s really significant,” dermatology professor and senior study author Brett King MED ’05 said.

The clinical trials began in July 2014 with the enrollment of 30 patients who had severe AA. King said that he then shared the protocol for the study with researchers at the Stanford School of Medicine, who enrolled 36 additional patients in January 2015. Of the 66 patients, 32 percent saw recovery of more than half of the hair they had lost, while 32 percent saw the recovery of less than half of the hair lost. The remaining 36 percent experienced no effects of the drug.

The team of 14 researchers used changes in genome expression to forecast the responsiveness of the patients, said Justin Ko, a Stanford professor of dermatology. He added that the team plans on further validating this practice in future trials.

King and Brittany Craiglow ’04 MED ’09, a dermatology and pediatrics professor who contributed to the study, said these outcomes show tofacitinib to likely be an effective treatment for AA.

“That a third of patients achieved a very brisk response and two thirds achieved a response, when you consider those statistics over 66 patients, that really is evidence of efficacy,” King said.

The clinical trials were a result of a fall 2013 case study, in which King was confronted with a patient seeking treatment for psoriasis, a condition in which one’s skin becomes red and itchy. King said that it was apparent to him that the patient also suffered from severe AA.

The results of a Columbia University lab study released earlier in the year had shown that Janice Kinase Inhibitors — a class of immune-suppressant drugs, to which tofacitinib belongs — had reversed AA’s effects in mouse models. King was also aware of JAK inhibitors’ prior use to treat psoriasis, so he attempted to “kill two birds with one stone” by using tofacitinib to treat both conditions simultaneously.

The results of King’s case study, which were published in the Journal of Investigative Dermatology in June 2014, showed the patient’s transformation from complete hairlessness to almost normal conditions, triggering enthusiasm in doctors and patients worldwide. King said that within just over a day of the study’s release, he had received almost 400 emails from patients and physicians eager for the treatment.

Within a month of the release, King and Craiglow assembled a clinical study to build on the findings.

“These papers I think really represent the first serious, really substantial number of patients [being studied to treat AA],” said Angela Christiano, the Columbia professor who published the JAK inhibitors study and performed much of the genetic analysis from the patients in the recent trials. Christiano, who has herself suffered from AA, said that the accumulation of evidence for tofacitinib’s treatment of AA is inspiring optimism among those affected by the disorder.

King said it is possible that AA’s visible symptoms cause anxiety and depression in patients, adding that it is difficult to explain to patients the lack of a treatment for the disorder.

“We remain guardedly optimistic,” Gary Sherwood, director of communications for the National Alopecia Areata Foundation, said about the new research. He added that in order for the FDA to approve tofacitinib for AA treatment, the treatment must be totally effective. King said that he estimates this process could take between three and five years.

Sherwood added that the medication is also relatively expensive — costing current arthritis patients approximately $25,000 a year, according to Forbes — and would have to be cheapened for widespread use.

King said that research is also necessary to prove to the pharmaceutical industry that AA occurs simultaneously with anxiety and depression in patients and that treatment of hair loss leads to enhanced quality of life.

New York University professor of clinical dermatology Michael Reed said “the findings [of the most recent study] are valid,” adding that the findings on JAK inhibitors represent “a huge breakthrough.”

Alopecia areata is not contagious.