medwireNews: Open-label follow-up results from the faSScinate trial suggest that patients with systemic sclerosis (SSc) who are treated with tocilizumab experience sustained improvements in skin fibrosis, but at the cost of an increased risk for infection.
Previous results from the double-blind period of the phase II trial demonstrated that patients who were randomly assigned to receive treatment with the interleukin-6 inhibitor had “clinically meaningful but not statistically significant” improvements in skin thickness and lung function at week 48 compared with those receiving placebo, say Dinesh Khanna (University of Michigan, Ann Arbor, USA) and study co-authors.
In the open-label extension phase of the trial, patients from both groups switched to weekly injections of tocilizumab 162 mg for an additional 48 weeks.
As reported in the Annals of the Rheumatic Diseases, the 27 patients who received tocilizumab throughout the study experienced continued improvements in modified Rodnan Skin Scores (mRSS) over approximately 2 years of follow-up, with mean decreases from baseline of 5.6 points at week 48 and 9.1 points at week 96.
And the 24 patients who transitioned from placebo to tocilizumab experienced a comparable 9.4-point improvement in mean mRSS from baseline to week 96, following an initial improvement of 3.1 points at the 48-week follow-up.
Moreover, none of the participants in either group experienced more than a 10% decline in percent predicted forced vital capacity (%pFVC) – indicating worsening lung function – during the open-label extension period.
In all, 153 adverse events (AEs) and five serious AEs were reported during the open-label extension period among patients in the continuous tocilizumab group, and 126 AEs and 11 serious AEs occurred in the placebo–tocilizumab group. Infections were the most commonly occurring AE among patients who switched to tocilizumab at week 48, with 12.9% of patients in this group experiencing serious infections from week 48 to 96.
“The frequencies of [serious] AEs and serious infections observed in faSScinate are consistent with those in other SSc studies,” and the safety results over the 96-week study were “consistent with the known safety profile of tocilizumab,” write Khanna and colleagues.
Although the researchers caution that the faSScinate trial was not designed for formal comparison of the two treatment arms during the open-label phase, meaning that the findings should be considered exploratory, they believe that “[t]ocilizumab may be a promising targeted therapy for patients with progressive SSc who have few treatment options.”
And they note that an ongoing phase III study “will investigate the efficacy and safety of tocilizumab compared with placebo in a 48-week double blind period and a 48-week open-label period to further investigate the findings of the phase II faSScinate trial.”
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