Background/Purpose: Methotrexate (MTX) is the cornerstone of rheumatoid arthritis (RA) therapy, but many patients do not achieve adequate response to oral therapy for reasons of tolerability or efficacy.^1,2 Subcutaneous (SC) MTX should be considered for RA patients who have an unsatisfactory response to oral MTX.³ In this analysis, RA patients switched from oral MTX to SC MTX monotherapy were evaluated to understand durability of response and disease control.

 Methods:  A prospective analysis of retrospective RA patient data collected from 2003-2011 at single site in the U.K.⁴ was performed.  Per institutional practice, incremental oral MTX dose increase was followed by a switch to SC MTX. Folic acid (5-15 mg) was given 1 day after SC MTX treatment as a matter of routine practice. Mean duration on SC MTX monotherapy following switch from oral MTX was documented via patient record review.

 Results: 112 RA patients were eligible for analysis. Mean age was 60.9 yrs (range 26-83 yrs) and mean disease duration was 8.3 years (range 0.5-46 yrs). 49 (44%) patients with an inadequate response to oral MTX for reasons of tolerability or efficacy were switched to SC MTX monotherapy and included in this analysis. (Table 1) 20 patients (41%) switched from oral MTX to SC MTX for reasons of tolerability. Amongst these: Mean DAS28 improved by 18% (-1.05), patients remained on SC MTX monotherapy for a mean of 28.6 months before additional treatment was added and 40% (8) achieved low disease activity (LDA) of DAS28 ≤3.2; 29 patients (59%) switched for reasons of efficacy. Amongst these: Mean DAS28 scores improved 25% (-1.26), patients remained on SC MTX monotherapy for a mean of 34.58 months before addition of other therapies and 24% (7) achieved LDA.

Conclusion: In this single-center analysis, RA patients with an inadequate response to oral MTX for reasons of efficacy and/or tolerability maintained satisfactory disease control and durable, long-term response when switched to SC MTX monotherapy.

Table 1.

Evaluable (n=49)	n	Pre- Switch DAS 28	Post- Switch DAS 28	DAS28 Change (Value, %)	Mean Duration on SC MTX monotherapy (months)	LDA (≤3.2) (n,%)	Remission (≤2.6) (n,%)
Inadequate Response to Oral MTX (Tolerability)	20	4.46	3.65	-1.05 (18%)	28.6	8 (40%)	6 (30%)
Inadequate Response to Oral MTX (Efficacy)	29	5.34	4.08	-1.26 (25%)	34.58	7 (24%)	2 (7%)

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/ra-patients-with-inadequate-response-to-oral-mtx-maintain-satisfactory-disease-control-and-durable-long-term-response-when-switched-to-sc-mtx-monotherapy/