A 24-Week, Phase IIa, Randomized, Double-Blind, Placebo-Controlled Study of Ziritaxestat in Early Diffuse Cutaneous Systemic Sclerosis.

OBJECTIVE

We undertook this study to explore the efficacy, safety, and tolerability of ziritaxestat, a selective autotaxin inhibitor, in patients with early diffuse cutaneous systemic sclerosis (dcSSc).

METHODS

NOVESA was a 24-week, multicenter, phase IIa, double-blind, placebo-controlled study. Adults with dcSSc were randomized to oral ziritaxestat 600 mg once daily or matching placebo. The primary efficacy end point was change from baseline in modified Rodnan skin score (MRSS) at week 24. Secondary end points assessed safety and tolerability; other end points included assessment of skin and blood biomarkers. Patients in NOVESA could enter a 104-week open-label extension (OLE).

RESULTS

Patients were randomized to ziritaxestat (n = 21) or placebo (n = 12). Reduction in MRSS was significantly greater in the ziritaxestat group versus the placebo group (-8.9 versus -6.0 units, respectively; P = 0.0411). Placebo patients switching to ziritaxestat in the OLE showed similar reductions in MRSS to those observed for ziritaxestat patients in the parent study. Ziritaxestat was well tolerated; the most frequent treatment-related treatment-emergent adverse events were headache and diarrhea. Circulating lysophosphatidic acid (LPA) C18:2 was significantly reduced, demonstrating ziritaxestat target engagement, and levels of fibrosis biomarkers were reduced in the blood. No differentially expressed genes were identified in skin biopsies. Significant changes in 109 genes were identified in blood samples.

CONCLUSION

Ziritaxestat resulted in significantly greater reduction in MRSS at week 24 than placebo; no new safety signals emerged. Biomarker analysis suggests ziritaxestat may reduce fibrosis. Modulation of the autotaxin/LPA pathway could improve skin involvement in patients with dcSSc. A plain language summary is provided in the Supplementary Material, available on the Arthritis & Rheumatology website at https://onlinelibrary.wiley.com/doi/10.1002/art.42477.