Background: Concomitant methotrexate (MTX) improves the therapeutic effect of biologic therapies in rheumatoid arthritis treatment. However, the influence of MTX on biologic therapy in psoriasis arthritis (PsA) has not yet been fully clarified, as data from randomized clinical studies are lacking. So far, it is only known, that PsA patients with inadequate response to MTX or non-steroidal anti-inflammatory drugs alone respond equally well to a subsequent biologic therapy.
Objectives: The aim of this study is to investigate whether MTX-naive patients achieve greater disease improvement with the combination of MTX and a biologic than with biologic monotherapy alone, and whether patients on MTX in whom a biologic therapy is additionally started would worsen if MTX is discontinued.
Methods: The current data situation and its limitations are presented. Furthermore, an investigator-initiated multicenter randomized clinical study in patients with active PsA is introduced (MUST study), which investigates the influence of placebo-controlled MTX combination therapy with the interleukin 12/23 inhibitor ustekinumab (UST) in order to close the existing evidence gap.
Results: The primary objective of the study is to demonstrate the non-inferiority of UST monotherapy compared to MTX/UST combination therapy as measured by mean DAS28 values at week 24. Of 196 planned patients, 77 have been included so far. Recruitment is still open.
Conclusion: The MUST study offers the ideal opportunity to investigate the influence of concomitant MTX in a controlled study design and to assess whether the addition of MTX to UST therapy or its continuation is beneficial for PsA patients.
Keywords: Antirheumatic agents; Interleukins; Psoriasis Arthritis; Tumor necrosis factor; Ustekinumab.