Rheumatoid Arthritis: Therapeutic Strategies After Inadequate Response to Initial TNF Inhibitor Therapy

Given the benefit of targeting TNF-α and IL-17 in RA, a novel molecule (ABT-122) that targets both human TNF and IL-17 has been developed. Two phase 1 studies⁸⁵ showed that dual neutralization of TNF and IL-17 with ABT-122 has characteristics acceptable for further exploration of therapeutic potential of this agent in TNF- and IL-17A–driven immune-mediated inflammatory diseases. Another novel drug is mavrilimumab, a human monoclonal antibody that targets granulocyte–macrophage colony-stimulating factor receptor α. A recent studyshowed that long-term treatment with mavrilimumab maintained response and was well-tolerated, with no increased incidence of treatment-emergent adverse events.⁸⁶

Namilumab (AMG203) is an immunoglobulin G1 monoclonal antibody that binds with high affinity to the GM-CSF ligand. In a phase 1b, randomized, double-blind study (PRIORA)⁸⁷ to assess namilumab in treating active, mild-to-moderate RA, significant improvement was seen in the DAS28-CRP score with namilumab (150 and 300 mg groups combined) compared with placebo at day 43 (P = 0.0117) and also 8 weeks after last dosing at day 99 (P = 0.0154). Adverse events were similar across different doses of namilumab and placebo, and included nasopharyngitis and exacerbation/worsening of RA. Another drug showing promise in RA is fosdagrocorat (PF-04171327), a potential dissociated agonist of the glucocorticoid receptor. A multicenter, double-blind, parallel-group, active- and placebo-controlled phase 2 study randomly assigned 86 patients to receive fosdagrocorat 10 mg, fosdagrocorat 25 mg, prednisone 5 mg, or placebo, all with stable background methotrexate therapy.⁸⁸ Both fosdagrocorat doses demonstrated efficacy in improving signs and symptoms in RA patients, with manageable adverse events.

Case Conclusion

There are several available treatment options for the case patient. Based on the PREMIER trial, solely increasing the dose of adalimumab is unlikely to provide a therapeutic benefit. Adding low-dose methotrexate (possibly via a parenteral route because of patient-reported gastrointestinal discomfort) might provide some synergistic and therapeutic effect. However, because of primary failure with TNFi therapy, she may benefit from the initiation of a biologic with a different mechanism of action (ie, swapping strategy). Therapeutic options include tocilizumab, abatacept, rituximab, and the Jak inhibitors (tofacitinib and baricitinib).

Summary

The optimal treatment of RA aims at achieving, and then maintaining, remission or a low disease activity. The choice of best treatment must be individualized to the patient, keeping in mind other factors, including comorbidities like fibromyalgia, history of diverticulitis (prior to use of tocilizumab), history of chronic obstructive pulmonary disease (prior to the use of abatacept), malignancy, and the presence of risk factors for infections (age, diabetes, chronic bronchitis). In a patient with inadequate response to initial biologic therapy, several options exist for the rheumatologist. Current evidence supports TNFi dose escalation for only infliximab; optimization of concurrent csDMARD or switching to a different csDMARD are other options. Cycling and swapping are other alternate approaches supported by many observational studies. While no head-to-head trials exist comparing the 2 strategies, data suggest superiority of the swapping strategy over the cycling approach. With the continuing development of novel therapeutics in RA, physicians have a growing list of treatment options to help their patients achieve disease remission.

Corresponding author: Namrata Singh, MD, 200 Hawkins Drive, Iowa City, IA 52242.

Financial disclosures: None.