ATLANTA –
Dr. John Stone
Of 250 patients treated in the double-blind portion of the trial, 215 entered the extension period (part 2 of the trial), and 197 (92%) completed all 3 years of the trial. A total of 38 of 81 (47%) extension participants in clinical remission (CR) at week 52 after receiving tocilizumab (Actemra) weekly maintained it throughout the extension, and 13 of 36 (36%) treated every other week maintained it, John Stone, MD, reported at the annual meeting of the American College of Rheumatology.
Notably, more of those 51 patients treated with tocilizumab who maintained CR throughout the extension were treatment free at the end of the extension, compared with those originally assigned to the placebo groups (65% vs. 45%), and their median time to first flare after stopping treatment was longer, said Dr. Stone, director of clinical rheumatology at Massachusetts General Hospital and associate professor of medicine in the division of rheumatology at Harvard Medical School, both in Boston.
For example, times to first flare were 575 and 428 days for the weekly and biweekly tocilizumab dosing groups – which each had 26-week prednisone tapering – but they were only 162 days in a placebo group with 26-week prednisone tapering and 295 days for patients in another placebo group with 52-week prednisone tapering, Dr. Stone explained. Retreatment with tocilizumab restored CR in patients who experienced flares after discontinuing treatment, he added.
Importantly, cumulative glucocorticoid doses over the 3 years were also lower in the tocilizumab groups (2,647 and 3,782 mg/day with weekly and biweekly tocilizumab and 5,248, and 5,323 mg/day in the placebo groups, respectively), Dr. Stone said.
No new safety signals were observed during the extension. Rates of serious adverse events (SAEs) and serious infections per 100 patient-years during the entire 3 years of the study were comparable among those who never received tocilizumab and those who received at least 1 dose (23.2 and 25.4 for SAEs and 4.6 and 3.5 for serious infections).
Detailed results of the extension period
GiACTA enrolled patients with GCA and randomized them to receive weekly or biweekly treatment with the interleukin-6 receptor–alpha inhibitor tocilizumab at doses of 162 mg delivered subcutaneously with a 26-week prednisone taper, or to the placebo groups with a 26- or 52-week prednisone taper. The results, reported in 2017, demonstrated the superiority of tocilizumab over placebo for providing sustained glucocorticoid-free remission and ultimately led to approval from Food and Drug Administration of the biologic agent for the treatment of GCA.
The current analysis was carried out to determine long-term safety, to explore maintenance of efficacy after discontinuation, and to “gain insight into the long-term glucocorticoid-sparing effects of tocilizumab,” Dr. Stone said.
He noted that the extension period was not randomized because of the way that patients in the “original four randomized groups had sorted themselves out into very different groups by virtue of their response in part 1 [of the trial],” which made randomization impossible because of the varying categories of patients.
Patients in the extension were also treated at investigators’ discretion to prevent “catastrophic GCA flares, vision loss, and other problems” that could potentially occur with discontinuation of the blinded injections in part 1, he said.
Nevertheless, the analysis “provides some incredibly important information about the management of GCA now,” he said, adding that the dramatic effect of the original randomization was still profound at 3 years “despite the fact that investigators could treat the patients as they wished.”
“Even at 3 years there was still a profound difference in the cumulative glucocorticoid [use], compared to those patients who were randomized to one of the placebo versus prednisone groups,” he explained.
However, the most important question from this study relates to what happened when weekly tocilizumab was stopped: Of the 81 patients in part 2 who were in CR on tocilizumab after part 1 of the study, 59 (73%) were not started on any treatment by their investigator, and of those, 25 (42%) maintained treatment-free remission for 2 full years following discontinuation of tocilizumab, he said.