Damian McNamara

June 20, 2017

MADRID — Rheumatoid arthritis remission rates are better when tocilizumab is added to methotrexate therapy than when a tumor necrosis factor (TNF) inhibitor is added, results from a multicenter, observational study show.

"We believe the clinical response may be deeper with the use of an IL-6 blocker than a TNF inhibitor," Ennio Giulio Favalli, MD, from Istituto Ortopedico Gaetano Pini in Milan, said here at the European League Against Rheumatism Congress 2017.

"Our 1-year retention rate is similar between TNF inhibitors and tocilizumab when the drugs are used as a first biotherapy in combination with methotrexate," he told Medscape Medical News. "But despite a similar retention rate, the remission rates are significantly different for tocilizumab-treated patients than TNF inhibitor–treated patients."

Dr Favalli and his colleagues identified 591 rheumatoid arthritis patients treated with either drug combination from January 2009 to May 2016 in the Lombardy Rheumatology Network (LOHREN) registry. The cohort was 77% female, mean age was 54 years, and mean duration of disease was 7.4 years.

There were 530 patients in the TNF inhibitor group: 195 taking etanercept, 163 taking adalimumab, 69 taking certolizumab pegol, 60 taking golimumab, and 43 taking infliximab. The other 61 patients were taking tocilizumab, a biologic approved by the US Food and Drug Administration for adults with moderately to severely active rheumatoid arthritis who failed to respond to at least one previous disease modifying antirheumatic drug.

Baseline characteristics in the two treatment groups were similar, except mean age was significantly higher in the tocilizumab group than in the TNF inhibitor group (58.2 vs 53.7 years; P = .021).

Overall, 68% of patients tested positive for rheumatoid factor and 78% tested positive for anti-citrullinated protein antibodies. At baseline, mean disease activity score in 28 joints, calculated using the erythrocyte sedimentation rate (DAS28-ESR), was 5.1. In this study, remission was defined as a DAS28-ESR score below 2.6.

Table. Retention and Remission Rates

Outcome Tocilizumab Group, % TNF Inhibitor Group, % P Value
Retention rate      
   6 months 88 84 .752
   12 months 76 72 .361
Remission rate      
   6 months 59 33 <.001
   12 months 59 35 <.001

 

Disparities in remission rates at 6 months and 12 months were similar when the data were corrected for treatment discontinuations.

These are real-world data, which is worthwhile.

"It's essential to determine the efficacy of drugs in large studies, especially when they show how drugs work in practice instead of in clinical trials. These are real-world data, which is worthwhile," said Xavier Teitsma, MD, from University Medical Center Utrecht in the Netherlands, who hosted a poster tour that included this research.

"Registries are always informative and can show how a drug works on a large scale, but there may be things you have to bear in mind when evaluating such data," he told Medscape Medical News.

For example, when retention rate is used as a measure of efficacy, it is useful to know whether a patient has stopped using a particular agent because of treatment success or because of adverse events, Dr Teitsma explained.

A potential limitation of this study is the fact that DAS28 was used to define remission; however, the researchers were limited by information available in the retrospective database, Dr Favalli pointed out. They plan to confirm the data using other validated tools that measure clinical remission, he reported.

Dr Favalli and Dr Teitsma have disclosed no relevant financial relationships.

European League Against Rheumatism (EULAR) Congress 2017: Abstract FRI0215. Presented June 16, 2017.

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