Background/Purpose: There is significant unmet need for new treatments to achieve disease control in dermatomyositis (DM), because of limited efficacy or toxicity of immunosuppressive agents or refractory disease.¹  Lenabasum is an oral, selective cannabinoid receptor type 2 (CB₂) agonist that resolves inflammation and attenuates fibrotic processes.   In a Phase 2 DM trial (NCT02466243), lenabasum vs. placebo treatment was well tolerated and associated with improvement in Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI) activity score and other efficacy outcomes.²  Efficacy and safety of lenabasum in DM is being tested in a global, randomized, double-blind, placebo-controlled Phase 3 trial (NCT03813160).  Preliminary baseline demographics, disease characteristics, and immunomodulating treatments in the first 129 enrolled subjects are presented as blinded data.  This is the largest interventional, placebo-controlled trial to date in DM.

Methods: 150 subjects will be enrolled in an ongoing trial with sites in North America, Europe, and Asia.  Subjects are ≥ 18 years of age, with a diagnosis of DM by Bohan and Peter or ACR/EULAR criteria.^3,4 Stable doses of immunomodulating medications are allowed.  Disease must be active by physician assessment with ≥ 1 of 3 criteria: 1. Physician global activity (MDGA) ≥ 3 cm [10 cm visual analogue scale (VAS)] and Manual Muscle Testing (MMT)-8 score ≤ 142 points (max 150); 2. Sum of MDGA, patient global activity (PtGA), and extramuscular global assessment (EMGA) VAS scores ≥ 10 cm (each 10 cm VAS scales); or 3. MDGA ≥ 3 cm and CDASI activity score > 14 (≥ moderate/severe skin activity).

Results: As of May 31, 2020, 129 subjects were dosed (Table 1). Most subjects are female (79%), white (70%), and middle-aged. More have classic (85%) than clinically amyopathic DM (15%).  Most (86%) have significant moderate/severe skin activity (CDASI > 14).  Most (87%) have muscle weakness with mean MMT-8 ± SD, 135 ± 14, and 37% have ≥ 1 elevated muscle enzyme test.  Physician-reported outcomes include EMGA VAS score = 5.4 ± 1.76 and MDGA VAS score = 5.5 ± 1.75.  Patient-reported outcomes include Health Assessment Questionnaire-Disability Index (HAQ-DI) score = 0.83 ± 0.713, pain score on HAQ-DI = 34 ± 27, and PtGA VAS score = 5.1 ± 2.32.  Glucocorticoids were used in 52% of subjects.  Eighty-four percent were on ≥ 1 immunomodulating drug and 56% were on ≥2.

Conclusion: Baseline demographics of enrolled subjects are as expected (majority white, female, and middle-aged) and reflects the estimated proportion of classic to clinically amyopathic patients in the overall DM population (~5:1).  Most subjects are concurrently receiving immunomodulatory drugs and have active, refractory disease with glucocorticoid use in half of subjects.  

1. J Am Acad Dermatol. 2020;82:267-81.
2. Arthritis Rheumatol. 2019;71 (suppl 10).
3. Arthritis Rheumatol. 2017;69:2271‐82.
4. N Engl J Med. 1975;292:344‐7 and N Engl J Med. 1975;292:403‐7.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/preliminary-baseline-subject-demographics-and-disease-characteristics-in-a-phase-3-clinical-trial-of-the-safety-and-efficacy-of-lenabasum-in-dermatomyositis-determine/