Cannabinoids in dermatology
Although a phase 3 trial of lenabasum did not meet its primary endpoint for treatment of diffuse cutaneous systemic sclerosis (dcSSc), the drug led to more improvement in participants who were not receiving background immunosuppressant therapy during the trial than that seen in participants who received the placebo. Lenabasum also had a favorable safety profile, according to findings presented at the annual European Congress of Rheumatology.
The double-blind, randomized, placebo-controlled trial involved 363 adults who had had dcSSc for up to 6 years. One third of the participants received 5 mg of oral lenabasum, one third received 20 mg, and one third received a placebo. Patients already receiving immunosuppressant therapy could continue to receive it during the trial if the dose had been stable for at least 8 weeks before screening and corticosteroid therapy did not exceed 10 mg prednisone per day or the equivalent.
“The decision to allow background immunosuppressant therapies was made to reflect real-world clinical practice,” coprincipal investigator Robert Dr. Spiera, MD, director of the Vasculitis and Scleroderma Program at the Hospital for Special Surgery, New York, told attendees.
“It is surprising that we do not see any added efficacy of lenabasum in this trial, given the fact that the previous phase 2 trial in 42 patients did show a clear benefit of lenabasum over placebo in the same population,” Jeska K. de Vries-Bouwstra, MD, PhD, a rheumatologist at Leiden (the Netherlands) University Medical Center told this news organization. “Even more, the clinical response in the phase 2 study was supported by a greater change in gene expression in skin tissue of pathways involved in inflammation and fibrosis with lenabasum as compared to placebo.”
Background immunosuppressants contribute to unprecedented placebo responses
The researchers compared the ACR CRISS (Combined Response Index in Diffuse Cutaneous Systemic Sclerosis) score and several secondary endpoints at 52 weeks between the 123 participants who received the placebo and the 120 participants who received 20 mg of lenabasum. A total of 60% of the lenabasum group and 66% of the placebo group had a disease duration of 3 or fewer years, and the modified Rodnan skin score (mRSS) was 22 in the lenabasum group and 23.3 in the placebo group at baseline.
A large majority of participants in both groups – 89% in the lenabasum group and 84% in the placebo group – were receiving background immunosuppressant therapy during the trial. Specifically, 53% of each group was taking mycophenolate, and 23% of the lenabasum group and 32% of the placebo group were taking corticosteroids. In addition, 22% of the lenabasum group and 12% of the placebo group were on methotrexate, and 27% of the lenabasum group and 22% of the placebo group were on another immunosuppressant therapy.
Half of the placebo group and 58% of the lenabasum group were taking only one immunosuppressive therapy. About one-third of the lenabasum (32%) and placebo (34%) groups were taking two or more immunosuppressive therapies.
The primary endpoint at 52 weeks was not significantly different between the two groups: a CRISS score of 0.888 in the lenabasum group and 0.887 in the placebo group. A CRISS score of 0.6 or higher indicates likelihood that a patient improved on treatment. Patients with significant worsening of renal or cardiopulmonary involvement are classified as not improved (score of 0), regardless of improvements in other core items.
“We had very high CRISS scores in all three groups, and they were comparable in all three groups,” Dr. Spiera reported. Because improvement in placebo group far exceeded expectations, the researchers were unable to discern the treatment effect of lenabasum on top of the placebo effect.
The placebo group had better outcomes than expected because of the background immunosuppressant therapy, particularly the use of mycophenolate. When the researchers looked only at placebo participants, the CRISS score was 0.936 in the 97 patients receiving background immunosuppressant therapy of any kind and 0.935 in the 29 patients taking only mycophenolate with no other immunosuppressant therapy, compared with 0.417 in the 16 patients not receiving any background therapy.
In a prespecified analysis, the researchers investigated background immunosuppressive therapy as a mediator. The CRISS score for the 10 lenabasum participants not receiving background therapy was 0.811, compared with 0.417 seen in the placebo group patients not on background therapy.
Among the 173 participants taking mycophenolate in particular, the mycophenolate “had a statistically significant improvement on CRISS score that increased with each visit,” Dr. Spiera reported. The duration of mycophenolate therapy also affected efficacy results.
Patients who had been taking mycophenolate longer saw less improvement in their CRISS score over time. Those taking it more than 2 years at baseline had a CRISS score of 0.86, compared with 0.96 for those taking it for 1-2 years at baseline and 0.98 for those taking it from 6 months to 1 year at baseline. Those who had only been taking mycophenolate for up to 6 months at baseline had a CRISS score of 0.99. Meanwhile, patients not taking any background immunosuppressant therapies only had a CRISS score of about 0.35.