Abstract
Etanercept (ETN) is a disease-modifying anti-rheumatic drug (DMARD) used in the treatment of rheumatoid arthritis (RA) that works as a tumor necrosis factor inhibitor (TNF inhibitor) by blocking the effects of naturally occurring TNF. This review will evaluate the effect of ETN as a monotherapy or combination therapy with methotrexate (MTX) in the treatment of RA. This systematic review was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) 2020 guidelines. A systematic search was done on PubMed and Google Scholar from 1999 to 2023. Predefined eligibility criteria were set for selected studies, which include: free full-text articles published; randomized control trials (RCTs); systematic reviews and meta-analyses; and observational studies in a patient with RA treated with ETN as initial therapy or as an add-on to conventional disease-modified therapy. Hence, the data had been extracted, and a quality assessment of each study was done by two individual authors. When comparing patients who received 15-25 mg of MTX with those who also received 25 mg of ETN in combination, 71% achieved American College of Rheumatology 20 (ACR20) by 24 weeks, compared to 27% in the MTX and placebo groups (p<0.001), and 39% achieved American College of Rheumatology 50 (ACR50), compared to 3% in the placebo + MTX group (p<0.001). Low disease activity (DAS 28) was more common in patients who had both MTX and ETN (64.5% with DAS <2.4 and 56.3% with DAS 28 <3.2) compared to patients who received only one medication (44.4% with DAS <2.4 and 33.2% with DAS 28 <3.2 for ETN and 38.6% with DAS <2.4 and 28.5% with DAS 28 <3.2 for MTX, with P<0.01). ETN demonstrated smaller changes from baseline in the modified Sharp score (TSS) and erosion scores (ES) at 12 months and two years, as well as a decreased change in the ES score at one year (with a trend of P value = 0.06 for the TSS score), in comparison to those receiving DMARD. Reactions at the injection site (42% vs. 7%, P<0.001) were the only events that occurred significantly more frequently in the ETN plus-MTX group. Combining ETN and MTX appears to help control RA symptoms by decreasing the American College of Rheumatology (ACR) response and DAS score, as well as halting the disease's progression on X-rays. The most common adverse effects were reactions to ETN administered alone at the injection site, likely because of patient awareness of the treatment received. There was also concern about tuberculosis and malignancy, but no recent data is available. Therefore, a larger clinical trial with longer follow-up is required to ascertain long-term safety and benefits.