Sirolimus may be an effective treatment for patients with persistent cutaneous sarcoidosis.
In a small clinical trial, 7 of 10 patients treated with sirolimus via oral solution had improvements in skin lesions after 4 months, which was sustained for up to 2 years after the study concluded.
The results suggested that mechanistic target of rapamycin (mTOR) inhibition is a potential therapeutic avenue for sarcoidosis, which the authors said should be explored in larger clinical trials.
In the past decade, there has been a growing amount of evidence suggesting mTOR’s role in sarcoidosis. In 2017, researchers showed that activation of mTOR in macrophages could cause progressive sarcoidosis in mice. In additional studies, high levels of mTOR activity were detected in human sarcoidosis granulomas in various organs, including the skin, lung, and heart.
Three case reports also documented using the mTOR inhibitor sirolimus to effectively treat systemic sarcoidosis.
“Although all reports observed improvement of the disease following the treatment, no clinical trial investigating the efficacy and safety of sirolimus in patients with sarcoidosis had been published” prior to this study, wrote senior author Georg Stary, MD, of the Medical University of Vienna and the Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria, and colleagues.
The findings were published in the The Lancet Rheumatology.
For the study, researchers recruited 16 individuals with persistent and glucocorticoid-refractory cutaneous sarcoidosis between September 2019 and June 2021. A total of 14 participants were randomly assigned to the topical phase of the study, whereas two immediately received systemic treatment. All treatment was conducted at Vienna General Hospital.
In the placebo-controlled, double-blinded topical treatment arm, patients received either 0.1% topical sirolimus in Vaseline or Vaseline alone (placebo) twice daily for 2 months. After a 1-month washout period, participants were switched to the alternate treatment arm for an additional 2 months.
Following this topical phase and an additional 1-month washout period, all remaining participants received systemic sirolimus via a 1-mg/mL solution, starting with a 6-mg loading dose and continuing with 2 mg once daily for 4 months. The primary outcome was change in Cutaneous Sarcoidosis Activity and Morphology Index (CSAMI) from baseline, with decrease of more than five points representing a response to treatment.
A total of 10 patients completed the trial.
There was no change in CSAMI in either topical treatment groups. In the systemic group, 70% of patients had clinical improvement in skin lesions, with three responders in this group having complete resolution of skin lesions. The median change in CSAMI was −7.0 points (P = .018).
This improvement persisted for 2 months following study conclusion, with more pronounced improvement from baseline after 2 years of drug-free follow-up (−11.5 points).
There were no serious adverse events reported during the study, but 42% of patients treated with systemic sirolimus reported mild skin reactions, such as acne and eczema. Other related adverse events were hypertriglyceridemia (17%), hyperglycemia (17%), and proteinuria (8%).
Compared with clinical outcomes with tofacitinib and tumor necrosis factor (TNF) inhibitors, “the strength of our study lies in the sustained treatment effect after drug withdrawal among all responders. This prolonged effect has not yet been explored with tofacitinib, whereas with TNF inhibitors disease relapse was seen in more than 50% of patients at 3-8 months,” the authors wrote.
The researchers also analyzed participants’ skin biopsies to gain a better understanding of how mTOR inhibition affected granuloma structures. They found that, at baseline, mTOR activity was significantly lower in the fibroblasts of treatment nonresponders than in responders. They speculated that lower expression of mTOR could make these granuloma-associated cells resistant to systemic sirolimus.
These promising findings combine “clinical response with a molecular analysis,” Avrom Caplan, MD, co-director of the Sarcoidosis Program at NYU Langone in New York City, told this news organization. He was not involved with the research. Adding molecular information to clinical outcome data “helps solidify that [the mTOR] pathway has relevance in the sarcoid granuloma formation.”
The study had a limited sample size — a challenge for many clinical trials of rare diseases, Dr. Caplan said. Larger clinical trials are necessary to explore mTOR inhibition in sarcoidosis, both he and the authors agreed. A larger trial could also include greater heterogeneity of patients, including varied sarcoid presentation and demographics, Dr. Caplan noted. In this study, all but one participants were White individuals, and 63% of participants were female.
Larger studies could also address important questions on ideal length of therapy, dosing, and where this therapy “would fall within the therapeutic step ladder,” Dr. Caplan continued.
Whether mTOR inhibition could be effective at treating individuals with sarcoidosis in other organs beyond the skin is also unknown.
“If the pathogenesis of sarcoid granuloma formation does include mTOR upregulation, which they are showing here…then you could hypothesize that, yes, using this therapy could benefit other organs,” he said. “But that has to be investigated in larger trials.”
The study was funded in part by a Vienna Science and Technology Fund project. Several authors report receiving grants from the Austrian Science Fund and one from the Ann Theodore Foundation Breakthrough Sarcoidosis Initiative. Dr. Caplan reported no relevant financial relationships.
A version of this article appeared on Medscape.com .