Background/Purpose: Little is known regarding the
real-world use and effectiveness of the interleukin-6 receptor α inhibitor
tocilizumab (TCZ) as monotherapy. The effectiveness of TCZ monotherapy in
patients with rheumatoid arthritis (RA) was evaluated using a US national
observational registry with > 40,000 patients with RA (Corrona).

Methods:
Between October
1, 2010, and March 31, 2015, patients with RA who newly initiated
TCZ monotherapy while not in remission (based on the Clinical Disease Activity
Index [CDAI]), and who had a follow-up visit at 1 year (± 3 months) with CDAI measurements at both visits were
identified. Outcomes assessed at 1 year included change in disease activity (median
change in CDAI), meaningful improvement in the modified Health Assessment
Questionnaire (mHAQ; change > 0.25) and achievement of a modified American College
of Rheumatology (mACR)20/50/70 response from baseline in all TCZ initiators and
were stratified by prior tumor necrosis factor inhibitor (TNFi) use. Outcomes
between the 1 and ≥ 2 prior TNFi groups were compared using chi-square
tests or t-tests, as appropriate.

Results: Of the 255 patients who newly initiated
TCZ monotherapy, 24 (9.4%) were TNFi naive, 93 (36.5%) received 1 prior TNFi
and 138 (54.1%) received ≥ 2 prior TNFis. At baseline, median (IQR) CDAI
was 19.5 (13.0-34.5), 22.2 (14.0-30.0) and 25.2 (19.0-34.1) in patients who
were previously treated with 0, 1 and ≥ 2 TNFis, respectively. At 12
months, there was improvement in the proportion of patients who achieved
remission or low disease activity in the overall cohort and across all TNFi groups
(Figure). CDAI remission occurred in 16.4%, 10.8% and 10.9% of patients
in the 0, 1 and ≥ 2 TNFi groups, respectively. The overall median decrease
in CDAI from baseline to 1 year and decreases stratified by TNFi group each exceeded
the minimal clinically important difference, with similar improvement in both
those with 1 and ≥ 2 prior TNFis (Table). Meaningful improvement
in mHAQ and mACR20/50/70 responses were also observed overall, with no statistically
significant differences across TNFi groups. Overall, the rate of serious infections
was 2.1 per 100 patient-years (PY) and the rate of cardiovascular events was
1.0 per 100 PY; no differences were observed by prior exposure to TNFis.

Conclusion: In this real-world cohort of TCZ
monotherapy initiators with primarily moderate to high disease activity and
prior TNFi exposure, substantial improvements in all clinical outcomes were
observed, with > 40% of patients overall achieving remission or low disease
activity (46%, 45% and 39% for patients with 0, 1 or ≥ 2 prior TNFis,
respectively).