FDA Approves Tocilizumab to Treat Systemic Sclerosis-Associated ILD

Systemic sclerosis, also known as scleroderma, is an autoimmune disease associated with fibrosis of the skin and other organs. Interstitial lung disease (ILD) can occur in 25–90% of systemic sclerosis patients, causing inflammation and lung scarring that can be life threatening.¹ Systemic sclerosis, which has no cure and may worsen over time. Mortality from all pulmonary complications in patients with scleroderma is estimated to be up to 33%. The incidence of scleroderma in the U.S. is approximately 20 cases per 1 million population.²

On March 4, the U.S. Food and Drug Administration (FDA) approved subcutaneous and intravenous tocilizumab (Actemra) to slow the rate of declining pulmonary function in adults with systemic sclerosis-associated ILD.^3–5 Previously, the FDA granted tocilizumab priority review designation for this condition, because systemic sclerosis-associated ILD is an incapacitating condition with inadequate treatment options.⁶ Tocilizumab is the first biologic therapy approved by the FDA to treat this disease.

Background
This FDA approval is based on data from the focuSSced clinical trial, a phase 3 randomized, double-blind, placebo-controlled study of adults (N=212) with systemic sclerosis.⁷ Supportive information from the phase 2/3, randomized, double-blind, placebo-controlled faSScinate study was also used for the approval.⁸

The focuSSced study did not meet its primary endpoint, which was the change from baseline to week 48 in the modified Rodnan Skin Score, a standard outcome measure for skin fibrosis in systemic sclerosis. The study also did not demonstrate a statistically significant effect on the modified Rodnan Skin Score.⁷ However, the patients who received tocilizumab maintained their baseline level of lung function as measured by the forced vital capacity (FVC), without further declination of lung capacity. The FVC is a common measure of lung function that assesses how much air can be exhaled, and the percent predicted FVC. The predicted FVC compares the study subject’s FVC to that expected for a healthy person of the same age, gender, race and height. In the faSScinate study, tocilizumab did not show significant skin thickening and fewer patients who received tocilizumab than patients that received placebo had a decline in their FVC of more than 10%.⁸

In patients with systemic sclerosis-associated ILD in the focuSSced study, tocilizumab-treated patients had a smaller decline in mean percent predicted FVC than placebo-treated patients (0.07% vs. -6.4%, mean difference 6.47%) and a smaller decline in FVC than placebo-treated patients (mean change -14 mL vs. -255 mL; mean difference 241 mL). The mean change from baseline to week 48 in the modified Rodnan Skin Score in tocilizumab-treated patients compared with placebo-treated patients was -5.88 vs. -3.77 (mean difference: -2.11).⁷