Real World Study Affirms Safety and Efficacy of TCZ for Treatment of GCA

Tocilizumab (TCZ) offers a reassuring safety profile, with low treatment discontinuation rates due to adverse events among patients treated for giant cell arteritis (GCA), according to study results published in The Journal of Rheumatology.

Tocilizumab is the first, and currently only, medication approved through the US Food and Drug Administration for the treatment of GCA. Guidelines from the American College of Rheumatology recommend starting TCZ therapy in combination with glucocorticoids for patients newly diagnosed with GCA.

Researchers compared the long-term safety and efficacy of TCZ therapy for treatment of GCA.

A retrospective chart review of patients from multiple Mayo Clinic Enterprise sites was conducted from January 1, 2010, to May 15, 2020. Patients aged at least 50 years with confirmed GCA treated with TCZ for at least 3 consecutive months, with at least 6 months of follow-up after TCZ initiation, were included in the analysis.

The number of relapses post-TCZ initiation was the primary study outcome. Adverse events of special interest (AESIs) were also documented.

A total of 114 patients with a mean age at diagnosis of 70.4 years and a median follow up duration of 34.5 (interquartile range [IQR], 19.5-54.8) months were included in the analysis. The study population consisted of 69 women and 45 men who were predominately White (99.1%).

Headache (70.8%), polymyalgia rheumatica (38.1%), and jaw claudication (35.7%) were among the most common symptoms present at GCA diagnosis. The median number of relapses prior to TCZ initiation was 1.0 (IQR, 0.0-2.0).

Over a median treatment duration of 2.3 years, treatment discontinuation occurred among 52 (45.6%) patients, with those discontinuing having a median TCZ treatment duration of 16.8 (IQR,10.3-28.0) months.

Following TCZ initiation, 68 patients were found to have at least one relapse overall, with 41 relapses occurring during TCZ treatment and 13 occurring after treatment discontinuation.

Inflammatory markers were the only statistically significant difference among patients relapsing following treatment discontinuation vs during TCZ treatment, with higher levels of erythrocyte sedimentation rate (ESR; median, 26.0 vs 3.5 mm/hr; IQR, 12.0-37.0 vs 1.0-10.0 mm/hr) and C-reactive protein (CRP; median, 16.1 vs 3.0 mg/L; IQR, 4.7-25.9 vs 3.0-8.5 mg/L) among the discontinuation group.

A significant reduction in annualized relapse rates (ARR) occurred among patients receiving TCZ treatment (0.28 relapses/person-years), compared with rates prior to initiation (0.84 relapses/person-years; P <.001).

Following discontinuation, the median time to first relapse was 8.4 months, with an ARR of 0.64 relapses/person-years. Among risk factors assessed for relapse after discontinuation, the presence of statin therapy was the only factor associated with a reduced risk (hazard ratio [HR], 0.38, 95% CI, 0.15-0.97).

Notably, only 14.9% of patents discontinued treatment due to an AESI; vision changes at TCZ initiation were the only significant factor associated with an increased risk for discontinuation (HR, 3.78, 95% CI, 1.35-10.57).

The generalizability of this study was limited by inclusion of a single enterprise cohort. Further limitations included the retrospective nature of the analysis and possible selection bias.

The study authors concluded, “Further studies are needed to determine the optimal duration of TCZ therapy. Additional research is necessary to identify which subsets of patients are more likely to remain in prolonged remission following TCZ discontinuation.”