Safety, Tolerability, and Efficacy of JBT-101 in Subjects With Dermatomyositis

Part A: An interventional, double-blind, randomized, placebo-control design will be used to
test JBT-101 in about 22 eligible male or female subjects ≥ 18 and ≤ 70 years of age with
moderate-to-severe active skin-predominant dermatomyositis.

Part B: A one-year open-label design to test JBT-101 in subjects who completed Part A without
permanent discontinuation of study product because of safety or tolerability reasons.

Inclusion Criteria (Part A):

- CDASI activity score ≥ 14;

- No difficulty with lifting or walking, and no more than 1.5 x the upper limit of
normal of creatine phosphokinase or aldolase;

- Failed at least 3 months treatment with hydroxychloroquine;

- Stable treatment for dermatomyositis for at least 28 days before Visit 1 (Day 1).

Inclusion Criteria (Part B):

- Completion of dosing in Part A without permanent discontinuation of study product
because of safety or tolerability reasons

Exclusion Criteria (Part A and B):

- Significant diseases or conditions other than DM that may influence response to the
study product or safety;

- Any one of the following values for laboratory tests at Screening:

1. A positive pregnancy test (or at Visit 1);

2. Hemoglobin < 10 g/dL;

3. Neutrophils < 1.0 x 10^9/L;

4. Platelets < 75 x 10^9/L;

5. Creatinine clearance < 50 ml/min according to modified Cockcroft-Gault equation;

6. Aspartate aminotransferase, alanine aminotransferase, or alkaline phosphatase >
2.5 x upper normal limit;

7. Total bilirubin ≥ 1.5 x upper limit of normal.

- Any other condition that, in the opinion of the Principal Investigator, is clinically
significant and may put the subject at greater safety risk, influence response to
study product, or interfere with study assessments.