Computerized planimetry to assess clinical responsiveness in a phase II randomized trial of topical R333 for discoid lupus erythematosus

Abstract

Background

R333 is a topical janus kinase and spleen tyrosine kinase inhibitor being evaluated for discoid lupus erythematosus (DLE) treatment. There is no validated measure to assess area of active DLE lesions.

Objectives

To evaluate R333 efficacy and assess a technique to measure responsiveness.

Methods

54 DLE patients were randomized in a double blind design to R333 or placebo. The primary endpoint was the proportion of patients achieving ≥50% decrease in erythema and scale based on lesional CLASI for all treated lesions at week 4. Two-dimensional area measurements for each lesion were recorded at baseline and week 1-6. 88 photographs (44 pre- and 44 post-treatment) were obtained from the trial and change in size of active areas was analyzed by computerized planimetry and physician assessed area change.

Results

36 patients were randomized to R333 and 18 patients were randomized to placebo. The primary endpoint was not achieved. There was a strong association between lesion activity and physician global assessment, a measure of activity of all treated lesions (p<10^-6). Photos of 42 patients assessed by computerized planimetry demonstrated excellent inter-rater and intra-rater reliability. Area change by computerized planimetry showed a strong correlation with physician assessed area change (Spearman r=0.72). Area change by two-dimensional measurements showed a weak correlation with physician assessed area change (Spearman r=0.29)

Conclusion

Four weeks of R333 treatment did not result in significant improvement in lesion activity. Lesion activity and area change using computerized planimetry are better determinants of responsiveness as compared to area change using two-dimensional measurements.

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