The results come from a Phase 2 trial (NCT02465437) which evaluated the safety and effectiveness of Resunab in 27 SSc patients, compared to placebo treatment in 15 patients.
Patients enrolled in the study had systemic sclerosis for up to six years and were allowed to receive stable doses of immunosuppressive drugs during the trial.
In the Resunab group, patients were divided into groups of nine people each, receiving different doses of the drug for the first month of the study: 5 mg once daily, 20 mg once daily, or 20 mg twice daily. After the first month, all patients in the Resunab group received 20 mg twice a day for the next eight weeks. After the end of the study, all patients were followed up from weeks 13 to 16.
Improvement was assessed using the American College of Rheumatology (ACR) Combined Response Index of the diffuse cutaneous Systemic Sclerosis (CRISS) score (a measure of improvement in SSc). This measure includes the modified Rodnan skin score (mRSS, which evaluates skin thickening); physician global assessment (MDGA); patient global assessment (PtGA); Health Assessment Questionnaire – Disability Index (HAQ-DI); and forced vital capacity (FVC; a measure of lung function).
In the Resunab group, 33 percent of patients showed significant improvement in the ACR CRISS score, whereas patients in the placebo group had no changes. Resunab also induced positive changes in the five individual domains of the CRISS score since baseline, observed as soon as week 4 or week 8.
Resunab treatment had a good safety profile as no serious, severe, or unexpected side effects were reported. Among the 27 patients who were treated with this drug, only one quit from the study due to moderate dizziness.
“This is the first double-blind, randomized, placebo-controlled trial in diffuse cutaneous systemic sclerosis to demonstrate a clinical benefit using the CRISS as an endpoint, with a drug that was safe and well tolerated in the trial,” Robert Spiera, MD, principal investigator of the study, said in a news release. “These results bring hope to patients and their physicians that [Resunab] may be an effective drug for systemic sclerosis where currently there are no proven treatments.”
Resunab acts by activating the cannabinoid receptor type 2 (CB2) expressed in immune cells. By binding to CB2, Resunab promotes the activation of mechanisms that improve inflammation and control the development of fibrosis.
“The positive results of this study exceed our expectations and validate the unique mechanism of action of [Resunab],” said Corbus CEO Yuval Cohen, PhD. “Our drug previously demonstrated clear and consistent evidence of activity in cellular and animal models as well as in healthy volunteers, repeatedly showing that its engagement with the CB2 receptor and its activation of inflammatory resolution translates into a potent effect on inflammation and fibrosis.”
“With the data from this Phase 2 study, we now show that this mechanism of action provided clinical benefit in patients with systemic sclerosis in this trial,” he said, adding that Corbus is looking forward to the next stages of clinical development, and is grateful to the patients, physicians and others who took part in the trial.
Earlier this year, the U.S. Food and Drug Administration (FDA) granted permission to Corbus to start an open-label extension study to analyze the long-term safety and effectiveness of Resunab. Patients who participated in the Phase 2 trial are continuing their treatment for another year.
“We are excited about these positive clinical outcomes in the [Resunab] group in this study, especially given its short duration and relatively small number of diverse systemic sclerosis subjects,” said Barbara White, MD, chief medical officer of Corbus. “With these clinical data and findings of acceptable safety and tolerability, we plan to reach out to regulatory authorities to confirm the next steps forward.”