Next Article in Journal
Effect of Balance Training in Sitting Position Using Visual Feedback on Balance and Gait Ability in Chronic Stroke Patients
Next Article in Special Issue
A Review of Therapeutic Drug Monitoring in Patients with Inflammatory Bowel Disease Receiving Combination Therapy
Previous Article in Journal
Recent Advances in Sodium Magnetic Resonance Imaging and Its Future Role in Kidney Disease
Previous Article in Special Issue
Therapeutic Drug Monitoring of Infliximab in Acute Severe Ulcerative Colitis
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:

The Role of Low-Dose Oral Methotrexate in Increasing Anti-TNF Drug Levels and Reducing Immunogenicity in IBD

Kathryn Demase
Cassandra K. Monitto
Robert D. Little
1 and
Miles P. Sparrow
Department of Gastroenterology, Alfred Health and Monash University, Melbourne 3004, Australia
Department of Pharmacy, Alfred Health, Melbourne 3004, Australia
Author to whom correspondence should be addressed.
J. Clin. Med. 2023, 12(13), 4382;
Submission received: 1 June 2023 / Revised: 26 June 2023 / Accepted: 27 June 2023 / Published: 29 June 2023


Concomitant immunomodulation is utilised in combination with anti-TNF therapy for IBD primarily to increase drug levels and prevent anti-drug antibody formation. Whilst thiopurines have traditionally been the immunomodulator of choice in IBD populations, there are concerns regarding the long-term safety of the prolonged use of these agents: particularly an association with lymphoproliferative disorders. Given this, we have explored the existing literature on the use of low-dose oral methotrexate as an alternative immunomodulator for this indication. Although there is a lack of data directly comparing the efficacies of methotrexate and thiopurines as concomitant immunomodulators, the available literature supports the use of methotrexate in improving the pharmacokinetics of anti-TNF agents. Furthermore, low-dose oral methotrexate regimens appear to have comparable efficacies to higher-dose parenteral administration and are better tolerated. We suggest that clinicians should consider the use of low-dose oral methotrexate as an alternative to thiopurines when the primary purpose of concomitant immunomodulation is to improve anti-TNF pharmacokinetics.

1. Introduction

The role of anti-tumour necrosis factor (anti-TNF) agents within the treatment armamentarium of inflammatory bowel disease (IBD) is well established. Agents such as infliximab (IFX) and adalimumab (ADL) have changed the landscape of medical therapy for both the induction and maintenance of moderate-to-severe ulcerative colitis (UC) and Crohn’s disease (CD) [1,2,3,4,5,6] and now have over 20 years of efficacy and safety data for IBD [7]. Therapeutic drug monitoring (TDM) has become routine in optimising secondary loss of response to anti-TNF therapy in IBD. In particular, TDM of IFX has been shown to improve clinical outcomes and be more cost-effective than empirical dose escalation [8,9]. The data supporting TDM of ADL are, however, less robust [10]. A range of target trough drug levels have been associated with varying depths of clinical, biochemical, and endoscopic remission, as well as perianal fistula healing [11,12,13,14,15,16].
Combination therapy with immunomodulators such as thiopurines (azathioprine (AZA), mercaptopurine (6-MP)) or methotrexate (MTX) increases anti-TNF drug levels and decreases the formation of anti-drug antibodies (ADAs) [17,18,19]. The evidence for the benefits of concomitant immunomodulation with ADL is less consistent than that with IFX [20,21,22,23,24,25]. Thiopurines have traditionally been used as first-line immunomodulators in IBD. Whilst they are effective therapeutic agents both in combination and as monotherapy, their long-term use is associated with serious adverse events (AEs), such as infections, non-melanomatous skin cancers (NMSCs), and lymphoma [26], including hepatosplenic T-cell lymphoma [27]. Although rare, hepatosplenic T-cell lymphoma has high mortality, with a preponderance in young males. Conversely, MTX may have a more tolerable serious side effect profile. It is commonly used in rheumatological conditions both as monotherapy and in combination with anti-TNF agents; however, it is typically reserved for those who are intolerant to thiopurines in IBD [28]. Evidence for its use in IBD is limited to studies of clinical outcomes of parenteral MTX given at varying doses, with few studies addressing the outcomes of using oral MTX to improve anti-TNF pharmacokinetics [29].
This comprehensive literature review examines the current evidence available on the efficacy, safety, and optimal dosing of oral MTX when used as an immunomodulator in combination with anti-TNF therapy for IBD to optimise anti-TNF drug levels and reduce immunogenicity. For when concomitant immunomodulation is used for this purpose, rather than as a second therapeutic agent to treat disease activity, we propose the consideration of low-dose oral (≤12.5 mg/week) MTX, given its favourable safety profile and comparable efficacy.
We conducted a literature search using the PubMed Online database. The search was performed using the following linked search terms: “methotrexate” AND (“anti-TNF” OR “infliximab” OR “adalimumab” OR “golimumab” OR “certolizumab”) AND (“inflammatory bowel disease” OR “Crohn’s disease” OR “ulcerative colitis”) AND (“rheumatoid arthritis” OR “psoriasis” OR “ankylosing spondylitis”) AND (“trough level” OR “drug concentration” OR “anti-drug antibody”). The results were restricted to the English language and original research, presenting data on the efficacy of oral low-dose MTX as a concomitant immunomodulator with anti-TNF therapy, published before 1 May 2023. In total, 68 articles were identified, and their titles and abstracts were screened by one reviewer (KD) to ensure their relevance. After screening, seventeen articles were assessed for eligibility, with an additional four articles added from a review of the reference lists of the selected articles. Studies that investigated the general efficacy of concomitant immunomodulation with thiopurines and MTX but failed to stratify their data by type of immunomodulator were excluded. After review, 10 articles were chosen for discussion (Table 1).

2. Pharmacokinetics of Anti-TNFs and the Role of Methotrexate in Increasing Drug Levels and Reducing Immunogenicity

Whilst anti-TNF agents are an effective therapy for IBD, 23–46% of patients treated with standard dosing regimens of IFX or ADL develop secondary loss of response after 12 months [38]. There are multiple proposed pharmacokinetic and pharmacodynamic mechanisms that lead to low drug levels and loss of response. Firstly, clearance of these drugs is increased in active disease. Intestinal inflammation leads to faecal loss of IFX, with higher faecal IFX concentrations found in those with more severe disease and low serum albumin levels [39]. The inverse relationship between baseline albumin levels and anti-TNF clearance [40] may be explained by the interactions between IgG antibodies, such as IFX, or proteins, such as albumin, and the neonatal Fc Receptor (FcRn) [41]. FcRn is found on endothelial cells and plays a role in the recycling and transcytosis of IgG antibodies and serum proteins, preventing them from catabolism and prolonging their half-life. Additionally, elevated C-reactive protein (CRP) levels have been linked to lower IFX trough levels and loss of response in IBD patients [42,43]. The association between these acute phase reactants and reduced drug levels supports the notion that increased anti-TNF clearance correlates with the severity of the disease.
The most investigated mechanism, however, is the immunogenicity of these agents, which elicit ADA formation against the F(ab)2 fragment of the anti-TNF IgG molecule [44]. The presence of ADAs against IFX has been demonstrated to increase drug clearance [40,45,46]. Whilst all biological drugs induce immunogenicity, they do so at varying degrees. This is partly explained by the structural differences amongst anti-TNF agents, whereby lower immunogenicity rates are associated with the degree of humanisation of molecules [18]. A systematic review and meta-analysis by Thomas et al. found a significant difference in incidences of ADAs against IFX compared to ADL. IFX is a chimeric monoclonal antibody (mAb) comprising murine variable and human Fc regions, whilst ADL is a fully humanised mAb. As expected, the incidence of ADAs against ADL was lower than that with IFX (14.1% vs. 25.3%, respectively; p = 0.03) [18]. This partly explains the larger body of evidence supporting the use of immunomodulators in combination with IFX compared to other anti-TNF agents.

2.1. Efficacy of Concomitant Immunomodulation in Improving Anti-TNF Levels

Immunomodulators increase the serum concentrations of anti-TNFs. Although the exact mechanism is not well-established, it is presumed that they exert this function by reducing the formation of ADAs. In the SONIC trial, patients with active CD and who received a combination of IFX and AZA had higher IFX levels than those who received IFX monotherapy (3.5 µg/mL vs. 1.6 µg/mL, respectively; p < 0.001). These findings were associated with higher corticosteroid-free remission rates in the combination therapy group [47]. Although the advantage of the combination treatment may, in part, be due to an additive immunosuppressive effect of AZA on the underlying disease process, there was also a clear reduction in ADA formation in patients on combination therapy in comparison to monotherapy (0.9% vs. 14.6%, respectively). Post hoc analysis found increasing rates of remission with increasing serum IFX concentrations but no difference between those on combination therapy and those on monotherapy when stratified by drug level [48]. Combination IFX and AZA patients comprised 73.1% of those who achieved the highest quartile of IFX concentrations and only 23.5% of those in the lowest quartile. Furthermore, the addition of immunomodulators can impact outcomes at as early as 4 weeks, which is faster than the onset of their therapeutic efficacy [49]. The benefit of combination therapy has been seen with real-world data from the prospective PANTS UK cohort, which demonstrated that concomitant immunomodulator therapy with thiopurines or MTX prevented ADA formation against IFX and ADL, improved drug levels, and was associated with a higher 54-week clinical remission rate [23].

2.2. Mechanism of Action of Methotrexate in Improving Anti-TNF Pharmacokinetics

MTX is a potent folic acid antagonist with proven efficacy in CD treatment due to its anti-inflammatory and pro-apoptotic properties [50]. However, trials in adult patients with UC found no superiority to the placebo in induction or maintenance of remission [51,52]. MTX exerts its cytotoxic effect by blocking dihydrofolate reductase, interfering with DNA synthesis, and inhibiting de novo purine synthesis. These anti-inflammatory pathways may also enhance the efficacy of biologic agents by reducing TNF and IL-12/23 levels [53], even in the absence of any effect in reducing ADAs. The specific effects on immunological processes that may lead to reductions in ADA formation are complex and not fully understood. A distinct immunomodulatory pathway has been observed in preclinical animal models of immunogenicity and may account for MTX’s effects on ADA production. MTX exposure in mice appears to induce T and B cell anergy, thereby blunting their response to antigen stimulation [54,55]. The animals in these studies showed reduced ADA production towards recombinant human proteins when treated with MTX. Furthermore, this response persisted 32 weeks after MTX cessation. Unrelated recombinant human proteins were administered after MTX cessation, and the ADA response was preserved, suggesting that this mechanism is distinct from generalised immunosuppression. Additionally, other immunosuppressive medications, including rapamycin and cyclophosphamide, exhibited no significant effect on the ADA responses, further supporting a unique role of MTX beyond its established immunosuppressive and cytotoxic effects [54]. These “anergic effects” of MTX on T and B cells may explain the mechanism for reducing ADAs that target anti-TNF agents.

3. Efficacy of Methotrexate Compared to Thiopurines as Concomitant Immunomodulators

In contrast to rheumatological conditions, the use of MTX in combination with anti-TNF agents for concomitant immunomodulation in IBD is less common [17]. This may be due to the more limited role MTX plays as a therapeutic agent in adult IBD [56]. Thiopurines, on the other hand, have a robust evidence base for both CD and UC and, as such, are commonly used as monotherapy maintenance agents in many jurisdictions globally. Therefore, when the decision is made to add an anti-TNF agent in patients failing thiopurine monotherapy, most of the patients continue to receive thiopurines for concomitant immunomodulation, with MTX typically reserved for those who either have failed or are intolerant to thiopurines [57]. A preference for thiopurines over MTX is evident across studies that have evaluated the effects of concomitant immunomodulation, with the majority of cohorts showing thiopurine usage rates of 50–70% (Table 1). There may be a trend towards increasing use of MTX as a first-line immunomodulator in the paediatric population due to safety concerns regarding prolonged thiopurine exposure, particularly hepatosplenic T-cell lymphoma. A multi-centre retrospective cohort study found that the proportion of patients who received MTX as their first immunomodulator rose from 14% in 2002 to 60% in 2010 (p = 0.005) [57].

3.1. Efficacy of Methotrexate for Concomitant Immunomodulation with Anti-TNFs

A review of the literature pertaining to the efficacy of MTX in regard to anti-TNF pharmacokinetics in both rheumatology and IBD has been summarised in Table 1 and Table 2. Overall, MTX has consistently been shown to reduce the formation of ADAs and lead to higher anti-TNF levels. There may be a reduced effect when it is used in combination with ADL compared to with IFX; however, the data on this are mixed [35,36,37]. Two large, multi-centre randomised control trials that investigated the use of MTX in combination with ADL in rheumatoid arthritis and axial spondylarthritis found it to be effective in reducing rates of ADA formation, increasing trough levels, and achieving clinical responses [35,36]. Conversely, a small, randomised control trial in patients with psoriasis found that there were no differences in the ADL levels in those on monotherapy compared to those receiving concomitant MTX [37]. Despite this, the MTX group did have significantly lower rates of ADA formation and achieved more rapid clinical responses than those on ADL monotherapy. Furthermore, a retrospective observational study of 278 CD patients on IFX or ADL with concomitant immunomodulation with either thiopurines (71%) or MTX (29%) found that those who received thiopurines had higher ADL trough levels compared to those who received MTX [32]. Patients on ADL also had higher rates of endoscopic remission when treated in combination with a thiopurine compared to MTX. These differences were not observed in patients on IFX. Further studies comparing the differential effects of MTX and thiopurines when used in combination with ADL would help clarify these conflicting results.
The data on the effects of concomitant MTX on clinical outcomes in IBD are similarly conflicted. Two randomised control trials found no difference in the rate of treatment failure in those on IFX monotherapy compared to combination therapy with MTX; however, one did show an improvement when used in combination with ADL [58,59]. Conversely, a large prospective cohort study found that the combination of IFX and MTX had higher rates of corticosteroid-free deep remission and was less likely to develop secondary non-response compared to IFX monotherapy [19]. The retrospective data on the effects of varying doses of concomitant MTX on clinical outcomes are also mixed but overall suggest that there is no difference between high- and low-dose regimes [30,32,33].
The efficacy of adding a concomitant immunomodulator (thiopurines or MTX) in eliminating ADAs, improving drug levels, and recapturing clinical responses to anti-TNF therapy is more established. Three retrospective studies have investigated the effects of commencing immunomodulators in patients who had developed immunogenic loss of response to IFX or ADL [31,60,61]. In all three studies, the immunomodulators were associated with reduction and elimination of ADA titres, increases in anti-TNF trough levels, and restored clinical responses. Although only one study reported the differential effects of MTX compared to thiopurines, it found no difference inefficacy between agents on these outcomes [31]. Furthermore, the addition of an immunomodulator was more effective than dose intensification of anti-TNFs alone [61].

3.2. Efficacy of Methotrexate Compared to Thiopurines at Augmenting Anti-TNF Pharmacokinetics

In terms of transitioning to the preferential use of MTX for concomitant immunomodulation, the first question that must be answered is whether it is as effective as thiopurines at maintaining anti-TNF trough levels and preventing ADA formation. There have been only two prospective observational studies that have directly compared the efficacies of MTX and thiopurines in combination with anti-TNFs [19,28]. There was no difference in the anti-TNF drug levels between the groups in either study, and MTX was found to be as effective at reducing ADA formation as AZA. The first study was a prospective cohort study of 369 patients with IBD and on maintenance IFX, vedolizumab, or ustekinumab. It investigated the differences in pharmacokinetics between biologic monotherapy and combination therapy with either MTX or thiopurines at varying doses. MTX was given orally, with the majority (65.4%) in low doses of 12.5 mg/week. IFX drug levels were found to be significantly lower in those who received IFX monotherapy (3.8 µg/mL) compared to those on concomitant MTX (17.1 µg/mL, p = 0.0001) and thiopurines (14.5 µg/mL, p = 0.01), with a trend towards higher levels in the MTX group compared to the thiopurines (p = 0.07) [19]. The rates of ADA formation were higher in those on IFX monotherapy compared to combination therapy (OR 8.6; 95% CI 2.59–29.16); however, this was not stratified by type of immunomodulator. The second study followed a cohort of 174 patients with CD across three centres, all of whom were treated with IFX in an episodic on-demand schedule. In total, 37.3% received AZA, 28.7% received MTX, and 34% received no concomitant immunomodulator [28]. MTX was given only to those who had previous thiopurine intolerance. It was administered parenterally at 15 mg/week after a 12-week induction of 25 mg/week. Those researchers found that MTX was as effective at reducing ADA formation as AZA, and both significantly reduced the risk of ADA formation compared to IFX monotherapy. They also showed that there was no significant difference in the rate of ADAs in those who started their concomitant immunomodulators > 3 months prior to commencing IFX compared to those who started the immunomodulators at the time of IFX induction. There was no difference in the median IFX level in those receiving AZA or MTX; this was measured 4 weeks after each infusion (6.15 µg/mL vs. 5.65 µg/mL, respectively; p = 0.27) [28].

4. Optimal Methotrexate Dosing for Concomitant Immunomodulation

The optimal dose and route of administration of MTX to optimise anti-TNF levels and prevent ADA formation is yet to be determined. When used as a monotherapy for IBD, MTX has traditionally been given parenterally and in high doses of 15–25 mg weekly [56]. However, high-dose subcutaneous administration may be unnecessary when MTX is used for the purpose of augmenting the pharmacokinetics of anti-TNF agents (Table 1 and Table 2).
Oral MTX has been shown to be as effective as parenteral administration in improving clinical outcomes when used in combination with anti-TNFs [30,33], although there is a paucity of data available for direct comparison. A retrospective review of over 200 patients demonstrated no differences in clinical outcomes such as IBD-related hospitalisations or surgery, change in biologic therapy, and steroid initiation between concomitant oral and parenteral MTX [33]. MTX is absorbed in the proximal jejunum to a varying extent between individuals, resulting in a bioavailability ranging from 30 to 90% [62]. This was demonstrated in patients with a range of rheumatological and dermatological conditions and appears to be independent of gastrointestinal disease involvement. Indeed, two small studies of patients with quiescent CD found oral MTX to have a bioavailability of 73–86% compared to subcutaneous administration [63,64]. Evidence around potential reduced absorption in those with proximal small bowel disease is lacking [65].
The saturable, dose-dependent mechanism of MTX absorption means the bioavailability of the oral formulation is higher at lower doses of up to 15 mg [65]. This explains why MTX, at low doses of 10–12.5 mg/week, is sufficient to reduce ADA formation and increase anti-TNF levels in both rheumatology and IBD [19,29,34,35,37], as exemplified in the CONCERTO trial [35]. This large randomised double-blind parallel-armed study investigated the effects of oral MTX at 2.5 mg, 5 mg, 10 mg, and 20 mg/week doses in combination with ADL in almost 400 patients with rheumatoid arthritis. There were lower rates of ADAs with increasing doses of MTX of up to 10 mg, with corresponding increases in the mean ADL levels, of up to 6.5 µg/mL, for those on 10 mg/week compared to 4.4 µg/mL in the 2.5 mg/week group. This dose-dependent effect was limited to a ceiling of 10 mg/week, with no difference in ADL levels compared to the 20 mg/week group. Improvement in clinical disease activity also plateaued at an MTX dose of 10 mg/week. These results have been reiterated in IBD cohorts with MTX doses of 10–12.5 mg/week [19,29,33]. A prospective cohort study of patients with IBD on IFX found that concomitant oral MTX improved trough levels to 17.1 µg/mL compared to 3.8 µg/mL in those on IFX monotherapy (p = 0.001). The improvement in IFX levels with MTX was numerically higher than that with thiopurines (14.5 µg/mL), although this did not reach significance (p = 0.07). The majority of the patients in the MTX group received doses of 12.5 mg/week [19]. Similarly, a cross-sectional study of over 200 paediatric patients found that concomitant low-dose oral MTX increased IFX trough levels to 15.59 µg/mL compared to 12.35 µg/mL in those who received IFX monotherapy (p = 0.01) [29].

Role of Therapeutic Drug Monitoring in Guiding Methotrexate Dosing

Although TDM and metabolite monitoring are well-established for anti-TNFs and thiopurines, there is no such role to guide MTX administration. MTX is a prodrug that only inhibits purine synthesis once it has had a number of glutamic acid residues added to it to form MTX polyglutamates [66]. Long-chain MTX-polyglutamates (MTX-PGs) are not effluxed efficiently from cells and therefore are a measure of intra-cellular MTX concentration [67]. A systematic review of the use of MTX-PG monitoring in inflammatory arthopathies has demonstrated that there may be a role for TDM in targeting disease activity but that it was not useful in predicting MTX toxicity or AEs [68]. A small cross-sectional study in a paediatric Crohn’s cohort found a trend towards increased short-chain MTX-PGs in those who were in remission compared to those with active disease [67]. Conversely, a similar retrospective study in adult IBD patients found that increased long-chain MTX-PG concentrations were associated with worse clinical disease activity and a higher rate of AEs [69]. Given this paucity of evidence, there is no established role for TDM of MTX via polyglutamate testing.

5. Safety Profile of Methotrexate as a Concomitant Immunomodulator with Anti-TNF Agents

The side effect profile of thiopurines has been well-described, with a range of mild-to-moderate AEs reported [26,70]; however, it is the more serious AEs, including infections, NMSC, and lymphoma, associated with their prolonged use that cause concern. These risks are increased when thiopurines are used in combination with anti-TNF agents [27,71,72,73,74,75].
MTX has a similar mild-to-moderate side effect profile to that of thiopurines. In fact, a retrospective cohort study of almost 800 patients with IBD found that those on MTX were more likely to discontinue treatment due to nausea, fatigue, and hepatotoxicity than those on thiopurines [70]. Meanwhile, patients who took thiopurines had higher rates of pancreatitis and lower leukocyte and neutrophil counts at 1 year. The patients on MTX were older and had higher rates of prior immunomodulator intolerance compared to those on thiopurines. Oral MTX was better tolerated than subcutaneous administration, with significantly less fatigue (3% vs. 10%, respectively; p = 0.04) and a trend towards lower discontinuation rates (32% vs. 45%, respectively; p = 0.07). The researchers of that study also found that lower doses (<20 mg oral or <15 mg subcutaneous) were better tolerated, with numerically lower discontinuation rates (24% vs. 40%, respectively; p = 0.19) compared to higher doses (≥20 mg oral or ≥15 mg subcutaneous). Of note is that these lower doses are still higher than is required for concomitant immunomodulation with anti-TNF therapy. Supplementation with folic acid reduces the incidence of gastrointestinal side effects and hepatotoxicity, improves tolerability, and helps prevent cytopenias [76,77].
More serious but less common AEs of MTX include interstitial lung disease and pleural or pericardial serositis [78,79]. MTX is not, however, associated with lymphoproliferative disorders when used in monotherapy or in combination with anti-TNF agents [80]. Combination immunosuppressive therapy has raised concern around increasing risk of infective complications. Indeed, a population-based French study of over 190,000 IBD patients showed that concomitant thiopurine and anti-TNF therapy increased the risk of serious and opportunistic infections compared to anti-TNF monotherapy [72]. This same risk is not apparent with concomitant MTX. A large retrospective registry study of almost 8000 patients with rheumatoid arthritis reviewed the risk of infections in patients on combination MTX (mean dose of 13.2 mg/week) and anti-TNF therapy compared to monotherapy with either agent [81]. These data followed patients for 15,047 patient-years. Surprisingly, there were no increased rates of infection in those on concomitant MTX and anti-TNF compared to those on anti-TNF monotherapy (37.1/100 person-years, 95% CI [34.9–39.3] vs. 41.8/100 person-years, 95% CI [37.0–43.3], respectively) [81]. Whilst the risk may differ between rheumatoid arthritis and IBD, these data suggest that MTX may have a lower rate of infective complications than thiopurines.

6. Recommendations for the Use of Low-Dose Oral Methotrexate in Combination with Anti-TNF Agents

Given the potential safety benefits and demonstrated pharmacokinetic efficacy, we suggest clinicians consider using low-dose oral MTX as an alternative to thiopurines for concomitant immunomodulation with anti-TNF therapy for IBD. Low-dose oral MTX is particularly suitable when the primary aim of the concomitant immunomodulation is to reduce immunogenicity and increase anti-TNF drug levels rather than as a second therapeutic agent to treat active disease. Other clinical scenarios where low-dose MTX should be considered for concomitant immunomodulation include:
  • EBV-naïve patients, especially males (due to the risk of lymphoproliferative disorders);
  • Young males (due to the rare but devastating risk of hepatosplenic T-cell lymphoma);
  • Thiopurine-intolerant patients;
  • Homozygous thiopurine methyltransferase (TMPT)- or Nudix hydrolase-15 (NUDT15)-deficient patients.
Whilst MTX is contraindicated in pregnancy and should be discontinued at least 3 months prior to conception, it has been shown to be safe in males who are planning on fathering a child [82]. MTX should be avoided in those with chronic liver disease, and dose reductions may be required for those with renal impairment.

7. Conclusions

The available evidence suggests that MTX has comparable efficacy to thiopurines in augmenting the pharmacokinetics of anti-TNF agents. It has also been demonstrated to eliminate ADAs, increase trough levels, and recapture clinical responses in those with loss of response and on anti-TNF monotherapy. There are, however, a lack of head-to-head data comparing these two agents as concomitant immunomodulators. Given the heterogeneity of the dosing regimens that have been studied to date, further investigation with more stringent subgroup analyses and consistent MTX doses will help clarify these findings. Overall, low-dose oral MTX (i.e., 10–12.5 mg weekly) is better tolerated and appears to be as effective as higher-dose parenteral administration in improving anti-TNF pharmacokinetics. Furthermore, given a potentially more favourable serious AE profile compared to thiopurines, low-dose oral MTX may be considered as an alternative first-line option for concomitant immunomodulation alongside anti-TNF therapy.

Author Contributions

Conceptualisation, K.D., R.D.L. and M.P.S.; methodology, K.D., R.D.L. and M.P.S.; literature search and screening, K.D.; original draft preparation, K.D. and C.K.M.; review and editing, K.D., C.K.M., R.D.L. and M.P.S.; supervision, R.D.L. and M.P.S. All authors have read and agreed to the published version of the manuscript.


This research received no external funding.

Conflicts of Interest

R.D.L. has received educational support from Celltrion Healthcare and Janssen and research support from Celltrion Healthcare. M.P.S. has received educational grants or research support from Ferring, Orphan, Gilead, and Celltrion; has received speaker’s fees from Janssen, Abbvie, Ferring, Takeda, Pfizer, Shire, and Celltrion; and has served on advisory boards for Janssen, Takeda, Pfizer, Celgene, Abbvie, MSD, Emerge Health, Gilead, BMS, and Celltrion.


  1. Hanauer, S.B.; Feagan, B.G.; Lichtenstein, G.R.; Mayer, L.F.; Schreiber, S.; Colombel, J.F.; Rachmilewitz, D.; Wolf, D.C.; Olson, A.; Bao, W.; et al. Maintenance infliximab for Crohn’s disease: The ACCENT I randomised trial. Lancet 2002, 359, 1541–1549. [Google Scholar] [CrossRef]
  2. Rutgeerts, P.; Sandborn, W.J.; Feagan, B.G.; Reinisch, W.; Olson, A.; Johanns, J.; Travers, S.; Rachmilewitz, D.; Hanauer, S.B.; Lichtenstein, G.R.; et al. Infliximab for induction and maintenance therapy for ulcerative colitis. N. Engl. J. Med. 2005, 353, 2462–2476. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  3. Hanauer, S.B.; Sandborn, W.J.; Rutgeerts, P.; Fedorak, R.N.; Lukas, M.; MacIntosh, D.; Panaccione, R.; Wolf, D.; Pollack, P. Human anti-tumor necrosis factor monoclonal antibody (adalimumab) in Crohn’s disease: The CLASSIC-I trial. Gastroenterology 2006, 130, 323–333. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  4. Sandborn, W.J.; Hanauer, S.B.; Rutgeerts, P.; Fedorak, R.N.; Lukas, M.; MacIntosh, D.G.; Panaccione, R.; Wolf, D.; Kent, J.D.; Bittle, B.; et al. Adalimumab for maintenance treatment of Crohn’s disease: Results of the CLASSIC II trial. Gut 2007, 56, 1232–1239. [Google Scholar] [CrossRef] [Green Version]
  5. Colombel, J.F.; Sandborn, W.J.; Rutgeerts, P.; Enns, R.; Hanauer, S.B.; Panaccione, R.; Schreiber, S.; Byczkowski, D.; Li, J.; Kent, J.D.; et al. Adalimumab for maintenance of clinical response and remission in patients with Crohn’s disease: The CHARM trial. Gastroenterology 2007, 132, 52–65. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  6. Sands, B.E.; Anderson, F.H.; Bernstein, C.N.; Chey, W.Y.; Feagan, B.G.; Fedorak, R.N.; Kamm, M.A.; Korzenik, J.R.; Lashner, B.A.; Onken, J.E.; et al. Infliximab maintenance therapy for fistulizing Crohn’s disease. N. Engl. J. Med. 2004, 350, 876–885. [Google Scholar] [CrossRef]
  7. D’Haens, G.R.; van Deventer, S. 25 years of anti-TNF treatment for inflammatory bowel disease: Lessons from the past and a look to the future. Gut 2021, 70, 1396–1405. [Google Scholar] [CrossRef]
  8. Steenholdt, C.; Brynskov, J.; Thomsen, O.Ø.; Munck, L.K.; Fallingborg, J.; Christensen, L.A.; Pedersen, G.; Kjeldsen, J.; Jacobsen, B.A.; Oxholm, A.S.; et al. Individualised therapy is more cost-effective than dose intensification in patients with Crohn’s disease who lose response to anti-TNF treatment: A randomised, controlled trial. Gut 2014, 63, 919–927. [Google Scholar] [CrossRef]
  9. Adedokun, O.J.; Sandborn, W.J.; Feagan, B.G.; Rutgeerts, P.; Xu, Z.; Marano, C.W.; Johanns, J.; Zhou, H.; Davis, H.M.; Cornillie, F.; et al. Association between serum concentration of infliximab and efficacy in adult patients with ulcerative colitis. Gastroenterology 2014, 147, 1296–1307.e5. [Google Scholar] [CrossRef] [Green Version]
  10. Gibson, D.J.; Ward, M.G.; Rentsch, C.; Friedman, A.B.; Taylor, K.M.; Sparrow, M.P.; Gibson, P.R. Review article: Determination of the therapeutic range for therapeutic drug monitoring of adalimumab and infliximab in patients with inflammatory bowel disease. Aliment. Pharmacol. Ther. 2020, 51, 612–628. [Google Scholar] [CrossRef]
  11. Mitrev, N.; Vande Casteele, N.; Seow, C.H.; Andrews, J.M.; Connor, S.J.; Moore, G.T.; Barclay, M.; Begun, J.; Bryant, R.; Chan, W.; et al. Review article: Consensus statements on therapeutic drug monitoring of anti-tumour necrosis factor therapy in inflammatory bowel diseases. Aliment. Pharmacol. Ther. 2017, 46, 1037–1053. [Google Scholar] [CrossRef] [Green Version]
  12. Ungar, B.; Levy, I.; Yavne, Y.; Yavzori, M.; Picard, O.; Fudim, E.; Loebstein, R.; Chowers, Y.; Eliakim, R.; Kopylov, U.; et al. Optimizing Anti-TNF-α Therapy: Serum Levels of Infliximab and Adalimumab Are Associated with Mucosal Healing in Patients with Inflammatory Bowel Diseases. Clin. Gastroenterol. Hepatol. 2016, 14, 550–557.e2. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  13. Yarur, A.J.; Kanagala, V.; Stein, D.J.; Czul, F.; Quintero, M.A.; Agrawal, D.; Patel, A.; Best, K.; Fox, C.; Idstein, K.; et al. Higher infliximab trough levels are associated with perianal fistula healing in patients with Crohn’s disease. Aliment. Pharmacol. Ther. 2017, 45, 933–940. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  14. Mitrev, N.; Kariyawasam, V.; Leong, R.W. Editorial: Infliximab trough cut-off for perianal Crohn’s disease—another piece of the therapeutic drug monitoring-guided infliximab dosing puzzle. Aliment. Pharmacol. Ther. 2017, 45, 1279–1280. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  15. Papamichael, K.; Cheifetz, A.S.; Melmed, G.Y.; Irving, P.M.; Vande Casteele, N.; Kozuch, P.L.; Raffals, L.E.; Baidoo, L.; Bressler, B.; Devlin, S.M.; et al. Appropriate Therapeutic Drug Monitoring of Biologic Agents for Patients with Inflammatory Bowel Diseases. Clin. Gastroenterol. Hepatol. 2019, 17, 1655–1668.e3. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  16. Cheifetz, A.S.; Abreu, M.T.; Afif, W.; Cross, R.K.; Dubinsky, M.C.; Loftus, E.V.; Osterman, M.T.; Saroufim, A.; Siegel, C.A.; Yarur, A.J.; et al. A Comprehensive Literature Review and Expert Consensus Statement on Therapeutic Drug Monitoring of Biologics in Inflammatory Bowel Disease. Am. J. Gastroenterol. 2021, 116, 2014–2025. [Google Scholar] [CrossRef]
  17. Garcês, S.; Demengeot, J.; Benito-Garcia, E. The immunogenicity of anti-TNF therapy in immune-mediated inflammatory diseases: A systematic review of the literature with a meta-analysis. Ann. Rheum. Dis. 2013, 72, 1947–1955. [Google Scholar] [CrossRef] [PubMed]
  18. Thomas, S.S.; Borazan, N.; Barroso, N.; Duan, L.; Taroumian, S.; Kretzmann, B.; Bardales, R.; Elashoff, D.; Vangala, S.; Furst, D.E. Comparative Immunogenicity of TNF Inhibitors: Impact on Clinical Efficacy and Tolerability in the Management of Autoimmune Diseases. A Systematic Review and Meta-Analysis. BioDrugs Clin. Immunother. Biopharm. Gene Ther. 2015, 29, 241–258. [Google Scholar] [CrossRef]
  19. Yarur, A.J.; McGovern, D.; Abreu, M.T.; Cheifetz, A.; Papamichail, K.; Deepak, P.; Bruss, A.; Beniwal-Patel, P.; Dubinsky, M.; Targan, S.R.; et al. Combination Therapy with Immunomodulators Improves the Pharmacokinetics of Infliximab But Not Vedolizumab or Ustekinumab. Clin. Gastroenterol. Hepatol. 2022, 22, S1542–S3565. [Google Scholar] [CrossRef]
  20. Karmiris, K.; Paintaud, G.; Noman, M.; Magdelaine-Beuzelin, C.; Ferrante, M.; Degenne, D.; Claes, K.; Coopman, T.; Van Schuerbeek, N.; Van Assche, G.; et al. Influence of trough serum levels and immunogenicity on long-term outcome of adalimumab therapy in Crohn’s disease. Gastroenterology 2009, 137, 1628–1640. [Google Scholar] [CrossRef]
  21. Matar, M.; Shamir, R.; Turner, D.; Broide, E.; Weiss, B.; Ledder, O.; Guz-Mark, A.; Rinawi, F.; Cohen, S.; Topf-Olivestone, C.; et al. Combination Therapy of Adalimumab with an Immunomodulator Is Not More Effective Than Adalimumab Monotherapy in Children With Crohn’s Disease: A Post Hoc Analysis of the PAILOT Randomized Controlled Trial. Inflamm. Bowel Dis. 2020, 26, 1627–1635. [Google Scholar] [CrossRef] [PubMed]
  22. Matsumoto, T.; Motoya, S.; Watanabe, K.; Hisamatsu, T.; Nakase, H.; Yoshimura, N.; Ishida, T.; Kato, S.; Nakagawa, T.; Esaki, M.; et al. Adalimumab Monotherapy and a Combination with Azathioprine for Crohn’s Disease: A Prospective, Randomized Trial. J. Crohn’s Colitis 2016, 10, 1259–1266. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  23. Kennedy, N.A.; Heap, G.A.; Green, H.D.; Hamilton, B.; Bewshea, C.; Walker, G.J.; Thomas, A.; Nice, R.; Perry, M.H.; Bouri, S.; et al. Predictors of anti-TNF treatment failure in anti-TNF-naive patients with active luminal Crohn’s disease: A prospective, multicentre, cohort study. Lancet. Gastroenterol. Hepatol. 2019, 4, 341–353. [Google Scholar] [CrossRef] [Green Version]
  24. Kopylov, U.; Al-Taweel, T.; Yaghoobi, M.; Nauche, B.; Bitton, A.; Lakatos, P.L.; Ben-Horin, S.; Afif, W.; Seidman, E.G. Adalimumab monotherapy versus combination therapy with immunomodulators in patients with Crohn’s disease: A systematic review and meta-analysis. J. Crohn’s Colitis 2014, 8, 1632–1641. [Google Scholar] [CrossRef] [Green Version]
  25. Chalhoub, J.M.; Rimmani, H.H.; Gumaste, V.V.; Sharara, A.I. Systematic Review and Meta-analysis: Adalimumab Monotherapy Versus Combination Therapy with Immunomodulators for Induction and Maintenance of Remission and Response in Patients with Crohn’s Disease. Inflamm. Bowel Dis. 2017, 23, 1316–1327. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  26. Luber, R.P.; Honap, S.; Cunningham, G.; Irving, P.M. Can We Predict the Toxicity and Response to Thiopurines in Inflammatory Bowel Diseases? Front. Med. 2019, 6, 279. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  27. Kotlyar, D.S.; Osterman, M.T.; Diamond, R.H.; Porter, D.; Blonski, W.C.; Wasik, M.; Sampat, S.; Mendizabal, M.; Lin, M.V.; Lichtenstein, G.R. A systematic review of factors that contribute to hepatosplenic T-cell lymphoma in patients with inflammatory bowel disease. Clin. Gastroenterol. Hepatol. 2011, 9, 36–41.e1. [Google Scholar] [CrossRef] [PubMed]
  28. Vermeire, S.; Noman, M.; Van Assche, G.; Baert, F.; D’Haens, G.; Rutgeerts, P. Effectiveness of concomitant immunosuppressive therapy in suppressing the formation of antibodies to infliximab in Crohn’s disease. Gut 2007, 56, 1226–1231. [Google Scholar] [CrossRef]
  29. Chi, L.Y.; Zitomersky, N.L.; Liu, E.; Tollefson, S.; Bender-Stern, J.; Naik, S.; Snapper, S.; Bousvaros, A. The Impact of Combination Therapy on Infliximab Levels and Antibodies in Children and Young Adults with Inflammatory Bowel Disease. Inflamm. Bowel Dis. 2018, 24, 1344–1351. [Google Scholar] [CrossRef]
  30. Colman, R.J.; Rubin, D.T. Optimal doses of methotrexate combined with anti-TNF therapy to maintain clinical remission in inflammatory bowel disease. J. Crohn’s Colitis 2015, 9, 312–317. [Google Scholar] [CrossRef] [Green Version]
  31. Ungar, B.; Kopylov, U.; Engel, T.; Yavzori, M.; Fudim, E.; Picard, O.; Lang, A.; Williet, N.; Paul, S.; Chowers, Y.; et al. Addition of an immunomodulator can reverse antibody formation and loss of response in patients treated with adalimumab. Aliment. Pharmacol. Ther. 2017, 45, 276–282. [Google Scholar] [CrossRef]
  32. Vasudevan, A.; Raghunath, A.; Anthony, S.; Scanlon, C.; Sparrow, M.P.; Gibson, P.R.; van Langenberg, D.R. Higher Mucosal Healing with Tumor Necrosis Factor Inhibitors in Combination with Thiopurines Compared to Methotrexate in Crohn’s Disease. Dig. Dis. Sci. 2019, 64, 1622–1631. [Google Scholar] [CrossRef] [PubMed]
  33. Borren, N.Z.; Luther, J.; Colizzo, F.P.; Garber, J.G.; Khalili, H.; Ananthakrishnan, A.N. Low-dose Methotrexate has Similar Outcomes to High-dose Methotrexate in Combination with Anti-TNF Therapy in Inflammatory Bowel Diseases. J. Crohn’s Colitis 2019, 13, 990–995. [Google Scholar] [CrossRef] [PubMed]
  34. Maini, R.N.; Breedveld, F.C.; Kalden, J.R.; Smolen, J.S.; Davis, D.; Macfarlane, J.D.; Antoni, C.; Leeb, B.; Elliott, M.J.; Woody, J.N.; et al. Therapeutic efficacy of multiple intravenous infusions of anti-tumor necrosis factor alpha monoclonal antibody combined with low-dose weekly methotrexate in rheumatoid arthritis. Arthritis Rheumatol. 1998, 41, 1552–1563. [Google Scholar] [CrossRef]
  35. Burmester, G.R.; Kivitz, A.J.; Kupper, H.; Arulmani, U.; Florentinus, S.; Goss, S.L.; Rathmann, S.S.; Fleischmann, R.M. Efficacy and safety of ascending methotrexate dose in combination with adalimumab: The randomised CONCERTO trial. Ann. Rheum. Dis. 2015, 74, 1037–1044. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  36. Ducourau, E.; Rispens, T.; Samain, M.; Dernis, E.; Le Guilchard, F.; Andras, L.; Perdriger, A.; Lespessailles, E.; Martin, A.; Cormier, G.; et al. Methotrexate effect on immunogenicity and long-term maintenance of adalimumab in axial spondyloarthritis: A multicentric randomised trial. RMD Open 2020, 6, e001047. [Google Scholar] [CrossRef]
  37. van der Kraaij, G.; Busard, C.; van den Reek, J.; Menting, S.; Musters, A.; Hutten, B.; de Rie, M.; Ouwerkerk, W.; van Bezooijen, S.J.; Prens, E.; et al. Adalimumab with Methotrexate vs. Adalimumab Monotherapy in Psoriasis: First-Year Results of a Single-Blind Randomized Controlled Trial. J. Investig. Dermatol. 2022, 142, 2375–2383.e6. [Google Scholar] [CrossRef]
  38. Ben-Horin, S.; Chowers, Y. Review article: Loss of response to anti-TNF treatments in Crohn’s disease. Aliment. Pharmacol. Ther. 2011, 33, 987–995. [Google Scholar] [CrossRef]
  39. Brandse, J.F.; van den Brink, G.R.; Wildenberg, M.E.; van der Kleij, D.; Rispens, T.; Jansen, J.M.; Mathôt, R.A.; Ponsioen, C.Y.; Löwenberg, M.; D’Haens, G.R. Loss of Infliximab into Feces Is Associated with Lack of Response to Therapy in Patients with Severe Ulcerative Colitis. Gastroenterology 2015, 149, 350–355.e2. [Google Scholar] [CrossRef] [Green Version]
  40. Fasanmade, A.A.; Adedokun, O.J.; Ford, J.; Hernandez, D.; Johanns, J.; Hu, C.; Davis, H.M.; Zhou, H. Population pharmacokinetic analysis of infliximab in patients with ulcerative colitis. Eur. J. Clin. Pharmacol. 2009, 65, 1211–1228. [Google Scholar] [CrossRef] [Green Version]
  41. Kuo, T.T.; Aveson, V.G. Neonatal Fc receptor and IgG-based therapeutics. mAbs 2011, 3, 422–430. [Google Scholar] [CrossRef] [PubMed]
  42. Roblin, X.; Marotte, H.; Leclerc, M.; Del Tedesco, E.; Phelip, J.M.; Peyrin-Biroulet, L.; Paul, S. Combination of C-reactive protein, infliximab trough levels, and stable but not transient antibodies to infliximab are associated with loss of response to infliximab in inflammatory bowel disease. J. Crohn’s Colitis 2015, 9, 525–531. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  43. Brandse, J.F.; Mathôt, R.A.; van der Kleij, D.; Rispens, T.; Ashruf, Y.; Jansen, J.M.; Rietdijk, S.; Löwenberg, M.; Ponsioen, C.Y.; Singh, S.; et al. Pharmacokinetic Features and Presence of Antidrug Antibodies Associate with Response to Infliximab Induction Therapy in Patients With Moderate to Severe Ulcerative Colitis. Clin. Gastroenterol. Hepatol. 2016, 14, 251–258.e2. [Google Scholar] [CrossRef] [PubMed]
  44. Ben-Horin, S.; Yavzori, M.; Katz, L.; Kopylov, U.; Picard, O.; Fudim, E.; Coscas, D.; Bar-Meir, S.; Goldstein, I.; Chowers, Y. The immunogenic part of infliximab is the F(ab′)2, but measuring antibodies to the intact infliximab molecule is more clinically useful. Gut 2011, 60, 41–48. [Google Scholar] [CrossRef] [PubMed]
  45. Ternant, D.; Aubourg, A.; Magdelaine-Beuzelin, C.; Degenne, D.; Watier, H.; Picon, L.; Paintaud, G. Infliximab pharmacokinetics in inflammatory bowel disease patients. Ther. Drug Monit. 2008, 30, 523–529. [Google Scholar] [CrossRef]
  46. Buurman, D.J.; Maurer, J.M.; Keizer, R.J.; Kosterink, J.G.; Dijkstra, G. Population pharmacokinetics of infliximab in patients with inflammatory bowel disease: Potential implications for dosing in clinical practice. Aliment. Pharmacol. Ther. 2015, 42, 529–539. [Google Scholar] [CrossRef]
  47. Colombel, J.F.; Sandborn, W.J.; Reinisch, W.; Mantzaris, G.J.; Kornbluth, A.; Rachmilewitz, D.; Lichtiger, S.; D’Haens, G.; Diamond, R.H.; Broussard, D.L.; et al. Infliximab, azathioprine, or combination therapy for Crohn’s disease. N. Engl. J. Med. 2010, 362, 1383–1395. [Google Scholar] [CrossRef] [Green Version]
  48. Colombel, J.F.; Adedokun, O.J.; Gasink, C.; Gao, L.L.; Cornillie, F.J.; D’Haens, G.R.; Rutgeerts, P.J.; Reinisch, W.; Sandborn, W.J.; Hanauer, S.B. Combination Therapy with Infliximab and Azathioprine Improves Infliximab Pharmacokinetic Features and Efficacy: A Post Hoc Analysis. Clin. Gastroenterol. Hepatol. 2019, 17, 1525–1532.e1. [Google Scholar] [CrossRef] [Green Version]
  49. Macaluso, F.S.; Sapienza, C.; Ventimiglia, M.; Renna, S.; Rizzuto, G.; Orlando, R.; Di Pisa, M.; Affronti, M.; Orlando, E.; Cottone, M.; et al. The addition of an immunosuppressant after loss of response to anti-tnfalpha monotherapy in inflammatory bowel disease: A 2-year study. Inflamm. Bowel Dis. 2018, 24, 394–401. [Google Scholar] [CrossRef]
  50. Nielsen, O.H.; Coskun, M.; Steenholdt, C.; Rogler, G. The role and advances of immunomodulator therapy for inflammatory bowel disease. Expert Rev. Gastroenterol. Hepatol. 2015, 9, 177–189. [Google Scholar] [CrossRef]
  51. Herfarth, H.; Barnes, E.L.; Valentine, J.F.; Hanson, J.; Higgins, P.D.R.; Isaacs, K.L.; Jackson, S.; Osterman, M.T.; Anton, K.; Ivanova, A.; et al. Methotrexate Is Not Superior to Placebo in Maintaining Steroid-Free Response or Remission in Ulcerative Colitis. Gastroenterology 2018, 155, 1098–1108.e9. [Google Scholar] [CrossRef] [PubMed]
  52. Chande, N.; Wang, Y.; MacDonald, J.K.; McDonald, J.W. Methotrexate for induction of remission in ulcerative colitis. Cochrane Database Syst. Rev. 2014, 2014, CD006618. [Google Scholar] [CrossRef] [PubMed]
  53. Bendtzen, K. Is there a need for immunopharmacologic guidance of anti-tumor necrosis factor therapies? Arthritis Rheumatol. 2011, 63, 867–870. [Google Scholar] [CrossRef]
  54. Garman, R.D.; Munroe, K.; Richards, S.M. Methotrexate reduces antibody responses to recombinant human alpha-galactosidase A therapy in a mouse model of Fabry disease. Clin. Exp. Immunol. 2004, 137, 496–502. [Google Scholar] [CrossRef] [PubMed]
  55. Joseph, A.; Munroe, K.; Housman, M.; Garman, R.; Richards, S. Immune tolerance induction to enzyme-replacement therapy by co-administration of short-term, low-dose methotrexate in a murine Pompe disease model. Clin. Exp. Immunol. 2008, 152, 138–146. [Google Scholar] [CrossRef] [PubMed]
  56. Torres, J.; Bonovas, S.; Doherty, G.; Kucharzik, T.; Gisbert, J.P.; Raine, T.; Adamina, M.; Armuzzi, A.; Bachmann, O.; Bager, P.; et al. ECCO Guidelines on Therapeutics in Crohn’s Disease: Medical Treatment. J. Crohn’s Colitis 2020, 14, 4–22. [Google Scholar] [CrossRef] [Green Version]
  57. Sunseri, W.; Hyams, J.S.; Lerer, T.; Mack, D.R.; Griffiths, A.M.; Otley, A.R.; Rosh, J.R.; Carvalho, R.; Grossman, A.B.; Cabrera, J.; et al. Retrospective cohort study of methotrexate use in the treatment of pediatric Crohn’s disease. Inflamm. Bowel Dis. 2014, 20, 1341–1345. [Google Scholar] [CrossRef]
  58. Feagan, B.G.; McDonald, J.W.; Panaccione, R.; Enns, R.A.; Bernstein, C.N.; Ponich, T.P.; Bourdages, R.; Macintosh, D.G.; Dallaire, C.; Cohen, A.; et al. Methotrexate in combination with infliximab is no more effective than infliximab alone in patients with Crohn’s disease. Gastroenterology 2014, 146, 681–688.e1. [Google Scholar] [CrossRef]
  59. Kappelman, M.D.; Wohl, D.A.; Herfarth, H.H.; Firestine, A.M.; Adler, J.; Ammoury, R.F.; Aronow, J.E.; Bass, D.M.; Bass, J.A.; Benkov, K.; et al. Comparative Effectiveness of Anti-TNF in Combination with Low-Dose Methotrexate vs Anti-TNF Monotherapy in Pediatric Crohn’s Disease: A Pragmatic Randomized Trial. Gastroenterology 2023, 165, 149–161.e7. [Google Scholar] [CrossRef]
  60. Ben-Horin, S.; Waterman, M.; Kopylov, U.; Yavzori, M.; Picard, O.; Fudim, E.; Awadie, H.; Weiss, B.; Chowers, Y. Addition of an immunomodulator to infliximab therapy eliminates antidrug antibodies in serum and restores clinical response of patients with inflammatory bowel disease. Clin. Gastroenterol. Hepatol. 2013, 11, 444–447. [Google Scholar] [CrossRef] [PubMed]
  61. Stallhofer, J.; Guse, J.; Kesselmeier, M.; Grunert, P.C.; Lange, K.; Stalmann, R.; Eckardt, V.; Stallmach, A. Immunomodulator comedication promotes the reversal of anti-drug antibody-mediated loss of response to anti-TNF therapy in inflammatory bowel disease. Int. J. Color. Dis. 2023, 38, 54. [Google Scholar] [CrossRef]
  62. van Roon, E.N.; van de Laar, M.A. Methotrexate bioavailability. Clin. Exp. Rheumatol. 2010, 28, S27–S32. [Google Scholar]
  63. Wilson, A.; Patel, V.; Chande, N.; Ponich, T.; Urquhart, B.; Asher, L.; Choi, Y.; Tirona, R.; Kim, R.B.; Gregor, J.C. Pharmacokinetic profiles for oral and subcutaneous methotrexate in patients with Crohn’s disease. Aliment. Pharmacol. Ther. 2013, 37, 340–345. [Google Scholar] [CrossRef] [Green Version]
  64. Kurnik, D.; Loebstein, R.; Fishbein, E.; Almog, S.; Halkin, H.; Bar-Meir, S.; Chowers, Y. Bioavailability of oral vs. subcutaneous low-dose methotrexate in patients with Crohn’s disease. Aliment. Pharmacol. Ther. 2003, 18, 57–63. [Google Scholar] [CrossRef] [PubMed]
  65. Cassinotti, A.; Batticciotto, A.; Parravicini, M.; Lombardo, M.; Radice, P.; Cortelezzi, C.C.; Segato, S.; Zanzi, F.; Cappelli, A.; Segato, S. Evidence-based efficacy of methotrexate in adult Crohn’s disease in different intestinal and extraintestinal indications. Ther. Adv. Gastroenterol. 2022, 15. [Google Scholar] [CrossRef]
  66. Goss, S.L.; Klein, C.E.; Jin, Z.; Locke, C.S.; Rodila, R.C.; Kupper, H.; Burmester, G.R.; Awni, W.M. Methotrexate Dose in Patients With Early Rheumatoid Arthritis Impacts Methotrexate Polyglutamate Pharmacokinetics, Adalimumab Pharmacokinetics, and Efficacy: Pharmacokinetic and Exposure-response Analysis of the CONCERTO Trial. Clin. Ther. 2018, 40, 309–319. [Google Scholar] [CrossRef] [PubMed]
  67. Morrow, R.; Funk, R.; Becker, M.; Sherman, A.; Van Haandel, L.; Hudson, T.; Casini, R.; Shakhnovich, V. Potential Role of Methotrexate Polyglutamates in Therapeutic Drug Monitoring for Pediatric Inflammatory Bowel Disease. Pharmaceuticals 2021, 14, 463. [Google Scholar] [CrossRef] [PubMed]
  68. Mohamed, H.J.; Sorich, M.J.; Kowalski, S.M.; McKinnon, R.; Proudman, S.M.; Cleland, L.; Wiese, M.D. The role and utility of measuring red blood cell methotrexate polyglutamate concentrations in inflammatory arthropathies—A systematic review. Eur. J. Clin. Pharmacol. 2015, 71, 411–423. [Google Scholar] [CrossRef]
  69. Brooks, A.J.; Begg, E.J.; Zhang, M.; Frampton, C.M.; Barclay, M.L. Red blood cell methotrexate polyglutamate concentrations in inflammatory bowel disease. Ther. Drug Monit. 2007, 29, 619–625. [Google Scholar] [CrossRef]
  70. Vasudevan, A.; Parthasarathy, N.; Con, D.; Nicolaides, S.; Apostolov, R.; Chauhan, A.; Bishara, M.; Luber, R.P.; Joshi, N.; Wan, A.; et al. Thiopurines vs methotrexate: Comparing tolerability and discontinuation rates in the treatment of inflammatory bowel disease. Aliment. Pharmacol. Ther. 2020, 52, 1174–1184. [Google Scholar] [CrossRef]
  71. Singh, S.; Facciorusso, A.; Dulai, P.S.; Jairath, V.; Sandborn, W.J. Comparative Risk of Serious Infections with Biologic and/or Immunosuppressive Therapy in Patients with Inflammatory Bowel Diseases: A Systematic Review and Meta-Analysis. Clin. Gastroenterol. Hepatol. 2020, 18, 69–81.e3. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  72. Kirchgesner, J.; Lemaitre, M.; Carrat, F.; Zureik, M.; Carbonnel, F.; Dray-Spira, R. Risk of Serious and Opportunistic Infections Associated with Treatment of Inflammatory Bowel Diseases. Gastroenterology 2018, 155, 337–346.e10. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  73. Peyrin-Biroulet, L.; Khosrotehrani, K.; Carrat, F.; Bouvier, A.M.; Chevaux, J.B.; Simon, T.; Carbonnel, F.; Colombel, J.F.; Dupas, J.L.; Godeberge, P.; et al. Increased risk for nonmelanoma skin cancers in patients who receive thiopurines for inflammatory bowel disease. Gastroenterology 2011, 141, 1621–1628.e5. [Google Scholar] [CrossRef] [PubMed]
  74. Siegel, C.A.; Marden, S.M.; Persing, S.M.; Larson, R.J.; Sands, B.E. Risk of lymphoma associated with combination anti-tumor necrosis factor and immunomodulator therapy for the treatment of Crohn’s disease: A meta-analysis. Clin. Gastroenterol. Hepatol. 2009, 7, 874–881. [Google Scholar] [CrossRef] [Green Version]
  75. Lemaitre, M.; Kirchgesner, J.; Rudnichi, A.; Carrat, F.; Zureik, M.; Carbonnel, F.; Dray-Spira, R. Association Between Use of Thiopurines or Tumor Necrosis Factor Antagonists Alone or in Combination and Risk of Lymphoma in Patients with Inflammatory Bowel Disease. JAMA 2017, 318, 1679–1686. [Google Scholar] [CrossRef]
  76. Shea, B.; Swinden, M.V.; Tanjong Ghogomu, E.; Ortiz, Z.; Katchamart, W.; Rader, T.; Bombardier, C.; Wells, G.A.; Tugwell, P. Folic acid and folinic acid for reducing side effects in patients receiving methotrexate for rheumatoid arthritis. Cochrane Database Syst. Rev. 2013, 2013, CD000951. [Google Scholar] [CrossRef]
  77. Whittle, S.L.; Hughes, R.A. Folate supplementation and methotrexate treatment in rheumatoid arthritis: A review. Rheumatology 2004, 43, 267–271. [Google Scholar] [CrossRef] [Green Version]
  78. Kremer, J.M.; Alarcón, G.S.; Weinblatt, M.E.; Kaymakcian, M.V.; Macaluso, M.; Cannon, G.W.; Palmer, W.R.; Sundy, J.S.; St Clair, E.W.; Alexander, R.W.; et al. Clinical, laboratory, radiographic, and histopathologic features of methotrexate-associated lung injury in patients with rheumatoid arthritis: A multicenter study with literature review. Arthritis Rheumatol. 1997, 40, 1829–1837. [Google Scholar] [CrossRef]
  79. Kremer, J. Major Side Effects of Low-Dose Methotrexate. Available online: (accessed on 18 May 2023).
  80. Wolfe, F.; Michaud, K. The effect of methotrexate and anti-tumor necrosis factor therapy on the risk of lymphoma in rheumatoid arthritis in 19,562 patients during 89,710 person-years of observation. Arthritis Rheumatol. 2007, 56, 1433–1439. [Google Scholar] [CrossRef]
  81. Greenberg, J.D.; Reed, G.; Kremer, J.M.; Tindall, E.; Kavanaugh, A.; Zheng, C.; Bishai, W.; Hochberg, M.C. Association of methotrexate and tumour necrosis factor antagonists with risk of infectious outcomes including opportunistic infections in the CORRONA registry. Ann. Rheum. Dis. 2010, 69, 380–386. [Google Scholar] [CrossRef] [Green Version]
  82. Sammaritano, L.R.; Bermas, B.L.; Chakravarty, E.E.; Chambers, C.; Clowse, M.E.B.; Lockshin, M.D.; Marder, W.; Guyatt, G.; Branch, D.W.; Buyon, J.; et al. 2020 American College of Rheumatology Guideline for the Management of Reproductive Health in Rheumatic and Musculoskeletal Diseases. Arthritis Rheumatol. 2020, 72, 529–556. [Google Scholar] [CrossRef] [PubMed] [Green Version]
Table 1. Summary of original research reporting efficacy of low-dose MTX as a concomitant immunomodulator with anti-TNF therapy.
Table 1. Summary of original research reporting efficacy of low-dose MTX as a concomitant immunomodulator with anti-TNF therapy.
StudyDesignAnti-TNFsMTX Dosing, mg/WeekCharacteristicsDrug Level, µg/mLADA FormationClinical Outcomes
Gastroenterology Studies
Colman (2015) [30]Retrospective reviewIFX
75% used PO MTX
25% used parenteral MTX

71% used LD-MTX (≤12.5 mg)
29% used HD-MTX (15–25 mg)
73 adult patients with IBD
- 74% with CD
- Active disease

All on anti-TNF therapy in combination with MTX
- 49% on ADL
- 40% on IFX
- 11% on CZP

Followed for 42 months

Secondary outcomes:
- Endoscopic inflammation
- Steroid use
- Therapy escalation
- Addition or escalation of concomitant therapy
- Surgery
--No difference in relapse rate between methods of MTX administration
- 37% PO vs. 27% parenteral; p = 0.56

HD-MTX more likely to maintain remission than LD-MTX; log-rank test p < 0.01

No difference in secondary outcomes indicating worsening disease between MTX doses (OR 1.14; 95% CI 0.61–2.13; p = 0.67)
Ungar (2017) [31]Retrospective multi-centre (3) reviewADLMix of PO and SC MTX (% not stated)

SC dose: 15–25 mg
PO dose: 10–15 mg
23 adult patients with IBD
- 91% with CD

All developed ADAs with LOR in ADL monotherapy; immunomodulator was added as salvage combination therapy
- 14 on thiopurines
- 9 on MTX
-48% of patients had elimination of ADAs
- No difference in type of immunomodulator; p = 0.5
Patients who had reversal of ADA achieved clinical responses and normalisation of inflammatory markers
Chi (2018) [29]Cross-sectional analysisIFX“Primarily low dose oral MTX, mean dose 11.6 mg ± 5.1 mg/week”223 paediatric and young adult patients with IBD
- 83.9% with CD

All on IFX
- 62.3% as monotherapy
- 37.7% as combination therapy

Of the combination therapy:
- 84.5% used MTX
- 15.5% used 6-MP
Higher TLs in combination therapy (15.59 ± 1.20) vs. monotherapy (12.35 ± 0.93); p = 0.01

Monotherapy (27.3%) more likely to have subtherapeutic TLs < 3.5 than combination therapy (8.3%): OR 0.13; 95% CI 0.04–0.39; p < 0.01

No difference in mean TL between the MTX (15.2) and MP (17.9) groups; p = 0.41
Combination therapy (9.5%) was less likely to result in ADAs than monotherapy (20%) (OR 0.3; 95% CI 0.1–0.7; p < 0.01)

Trend towards higher rates of ADAs in 6-MP (23.08%) vs. MTX (7.04%) use; p = 0.07
No difference in clinical or biochemical disease activity between IFX monotherapy and combination therapy
Vasudevan (2019) [32]Retrospective multi-centre (2) observational studyIFX
- 29% used LD-MTX (≤12.5 mg)
- 71% used HD-MTX (≥15 mg)
269 adult patients with CD

All on anti-TNF therapy and with ≥3 months of combination immunomodulator therapy
- 58% on IFX
- 42% on ADL
- 71% used thiopurines
- 29% used MTX
No difference in IFX TLs between thiopurines (5.3) and MTX (5.4); p = 0.63

Higher ADL TLs with thiopurines (7.2) vs. MTX (4.3) combination therapy; p = 0.03

The thiopurine combination achieved higher rates of therapeutic ADL levels (73%) vs. MTX (18%); p < 0.01
-Higher rates of endoscopic remission in the ADL group with thiopurine combinations (49%) vs. MTX (6%); p = 0.004

No differences in remission rate between immunomodulators when used in combination with IFX
- 65% on thiopurines vs. 54% on MTX; p = 0.09

No differences in rate of endoscopic remission between low- and high-dose MTX
Borren (2019) [33]Retrospective reviewIFX
PO and SC MTX, 7.5–25 mg

28% used LD-MTX (≤12.5 mg)
- 96.8% used PO

72% used HD-MTX (>12.5 mg)
- 39% used PO
222 adult patients with IBD
- 73.4% with CD

All on anti-TNF therapy with varying doses of MTX

- 38.1% LD-MTX users
- 37.7% HD-MTX users
- 44.4% LD-MTX users
- 40.9% HD-MTX users
- 9.5% LD-MTX users
- 7.0% HD-MTX users
- 7.9% LD-MTX users
- 4.4% HD-MTX users
--No difference in primary composite outcome (IBD-related hospitalisation or surgery, biological change, or steroid initiation) between the LD-MTX (37%) and HD-MTX (47%) groups; p = 0.15

Multi-variable analysis showed no difference in individual outcomes for either group
Yarur (2022)
Prospective cohort study IFXPO MTX
- 65.4% used LD-MTX (12.5 mg)
- 34.6% used HD-MTX (25 mg)
113 adult patients with IBD
- 73% with CD

All on IFX
- 23% on IFX monotherapy
- 23% on MTX in combination
- 54% on thiopurines in combination
Higher TLs in the combination MTX group (17.1 [IQR 9.7–23.7]) and thiopurine group (14.5 [IQR 4.5–18.8]) vs. monotherapy (3.8 [IQR 1.8–9.2]); p = 0.0001
- Only those on thiopurines combined with 6-TGNs > 145 had higher TLs than in monotherapy

Trend towards higher TL in MTX combination therapy than with thiopurines p = 0.07
Higher rates of ADAs in monotherapy than in combination therapy (OR8.6; 95% CI 2.58–29.16)
* Not stratified by type of combination therapy
Higher rates of steroid-free deep remission in combination therapy (71.3) vs. monotherapy (46.2); p = 0.02
- Use of MTX and thiopurines with 6-TGNs > 145 as combination therapy were both associated with remission
Rheumatology Studies
Maini (1998) [34]Multi-centre randomised, double-blind placebo-controlled trialIFXPO MTX, 7.5 mg101 adult patients with active RA

Randomised into seven groups
- IFX 1 mg/kg ± MTX
- IFX 3 mg/kg ± MTX
- IFX 10 mg/kg ± MTX
- Placebo infusion + MTX
Followed for 26 weeks
Combination with MTX showed consistently higher drug levels 6 weeks after the last infusion in those receiving IFX at 3 mg/kg and at 10 mg/kg

IFX 1mg/kg monotherapy resulted in undetectable TLs from week 4 vs. stable, detectable TLs in those receiving combination MTX
Rate of ADA formation was inversely proportional to IFX dose

MTX combination reduced ADA formation
- 53% of IFX 1 mg/kg vs. 15% with MTX
- 21% of IFX 3 mg/kg vs. 7% with MTX
- 7% of IFX 10 mg/kg vs. 0% with MTX
IFX (1 mg/kg) monotherapy was no better than placebo
- MTX combination achieved clinical responses in >60% of the group for a median of 16.5 weeks; p = 0.006 vs. IFX (1 mg/kg) monotherapy
Burmester (2013)
Randomised, double blind parallel-armed studyADLPO MTX:
2.5 mg
5 mg
10 mg
20 mg
395 adult patients with RA

All on ADL
Randomised 1:1:1:1 to combination therapy with different MTX doses
Followed for 26 weeks
Higher TLs with increasing MTX doses of up to 10 mg/week
- Mean TLs of 4.4 (±5.2), 5.7 (±4.9), 6.5 (4.4), 6.9 (3.4) for MTX at 2.5 mg, 5 mg, 10 mg, and 20 mg, respectively
Lower rates of ADAs with increasing MTX doses of up to 10 mg/week
- 21%, 13%, 6%, and 6% for MTX 2.5 mg, 5 mg, 10 mg, and 20 mg, respectively
Reduced disease activity with increasing MTX doses
- Higher proportion of patients meeting the primary endpoint with increasing MTX doses; p = 0.005
Ducourau (2020) [36]Multi-centre randomised trialADLSC MTX, 10 mg107 adult patients with axial spondylarthritis

All on ADL
Randomised 1:1 to ADL monotherapy vs. combination with MTX
- 51.4% monotherapy
- 48.6% combination

Followed for 26 weeks
MTX combination therapy was associated with higher TLs at all time points; p < 0.05

Those with ADAs had lower median TLs (1.43 [0.00–11.47]) compared to those without ADAs (8.66 [0.05–18.31]) at week 26; p < 0.05
Lower rates of ADAs in MTX combination therapy (25%) vs. ADL monotherapy (47.3%); p = 0.03
- MTX combination therapy reduced risk of ADA formation; RR 0.53 (95% CI 0.31–0.91)
Similar rates of clinically inactive disease by week 26 for both groups (40% ADL monotherapy vs. 37%; p = 0.9)
Dermatology Studies
van der Kraaij (2022) [37]Randomised control trialADLPO MTX, 10 mg61 adult patients with psoriasis

All on ADL
Randomised 1:1 to ADL monotherapy vs. combination with MTX
- 49% monotherapy
- 51% combination
No difference in median TL between groups; p = 0.26
- 5.9 [3.5–8.8] for monotherapy
- 6.8 [5.5–9.2] for combination

More monotherapy patients failed to reach therapeutic TLs > 3.2 at week 5 (6.5%) vs. with combination therapy (30%); p = 0.02
- This was not significant at week 49; 12.9 vs. 23.3%; p = 0.32
Higher rates of ADA formation in monotherapy group (60%) vs. combination therapy group (22.6%); p < 0.01

ADAs appeared earlier in monotherapy group vs. combination therapy group
- Week 5: 33.3 vs. 3.2%; p < 0.01
- Week 49: 46.7 vs. 38.7%; p = 0.31
Combination therapy had faster clinical improvement, with 83.9% achieving treatment goals in week 13 vs. 56.7% of monotherapy patients; p = 0.03
Abbreviations—Anti-TNF (anti-tumour necrosis factor), IFX (infliximab), ADL (adalimumab), CZP (certolizumab pegol), GOL (golimumab), MTX (methotrexate), PO (oral), SC (subcutaneous), LD (low-dose), HD (high-dose), IBD (inflammatory bowel disease), CD (Crohn’s disease), RA (rheumatoid arthritis), LOR (loss of response), TL (trough level), OR (odds ratio), CI (confidence interval), IQR (inter-quartile range), 6-MP (mercaptopurine), 6-TGNs (6-thioguanine nucleotide). * is to indicate a point of interest/qualifying remark relating to the above comment.
Table 2. Summary of original research reporting efficacy of high-dose MTX as a concomitant immunomodulator with anti-TNF therapy for IBD.
Table 2. Summary of original research reporting efficacy of high-dose MTX as a concomitant immunomodulator with anti-TNF therapy for IBD.
StudyDesignAnti-TNFsMTX Dosing, mg/WeekCharacteristicsDrug Level, µg/mLADA FormationClinical Outcomes
Vermeire (2007) [28]Multi-centre (3) prospective cohort studyIFXSC MTX at 15 mg (12-week induction with 25 mg)174 adult patients with IBD

All commenced IFX
(episodic, on-demand regime)
- 34% with IFX monotherapy
- 37.3% with AZA combination
- 28.7% with MTX combination
Higher median IFX levels in combination therapy (6.45) vs. monotherapy (2.42); p = 0.065
- No difference between MTX (5.65) and AZA (6.15); p = 0.27
Lower rates of ADA formation in combination therapy (46%) vs. monotherapy (73%); p < 0.001

MTX (44%, p = 0.002) and AZA (48%, p = 0.004) had equal efficacies against ADA formation vs. monotherapy

No difference in rate of ADA when immunomodulator started at time of IFX vs. preceding 3 months
Feagan (2014)
Double-blind, placebo-controlled, randomised trialIFXSC MTX at 25 mg
(escalated from 10 mg to 25 mg over 5 weeks)
126 adult patients with CD

All commenced IFX
Randomised 1:1
- IFX monotherapy (placebo)
- MTX combination
Trend towards higher TLs in MTX group (6.35) vs. monotherapy (3.75); p = 0.08Lower rates of ADA formation in MTX group (4%) vs. monotherapy (20%); p = 0.01No difference in rate of treatment failure at week 50 between MTX (30.6%) and monotherapy (29.8%) groups, (HR, 1.16; 95% CI 0.62–2.17)
Kappelman (2023) [59]Multi-centre (35), placebo-controlled, randomised trialIFX
Weight-based PO MTX
- 15 mg if >40 kg
- 12.5 mg if 30–40 kg
- 10 mg if 20–30 kg
297 paediatric (age < 21) patients with CD

All commenced either IFX or ADL
- 71% IFX
- 29% ADL

Randomised 1:1 and stratified by anti-TNF
- IFX monotherapy (placebo)
- MTX combination

Followed for 1–3 years
-No difference in ADA formation with MTX (34%) vs. placebo (47%) group for IFX (RR 0.72, 95% CI 0.49–1.07)

No difference for ADL; 15% with MTX vs. 21% with placebo (RR, 0.71 95% CI 0.24–2.07)

Those on ADL with ADAs were more likely to have treatment failure (64% vs. 36%, p = 0.03)

* Serum available for only 70% of patients
MTX use in those on ADL reduced the risk of treatment failure vs. placebo; HR 0.40 (95% CI 0.19–0.81, p = 0.01)

No significant differences between groups for those on IFX
Abbreviations—Anti-TNF (anti-tumour necrosis factor), IFX (infliximab), ADL (adalimumab), MTX (methotrexate), PO (oral), SC (subcutaneous), IBD (inflammatory bowel disease), CD (Crohn’s disease), TL (trough level), HR (hazard ratio), RR (relative risk), CI (confidence interval). * is used to indicate a point of interest/qualifying remark relating to this section.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Demase, K.; Monitto, C.K.; Little, R.D.; Sparrow, M.P. The Role of Low-Dose Oral Methotrexate in Increasing Anti-TNF Drug Levels and Reducing Immunogenicity in IBD. J. Clin. Med. 2023, 12, 4382.

AMA Style

Demase K, Monitto CK, Little RD, Sparrow MP. The Role of Low-Dose Oral Methotrexate in Increasing Anti-TNF Drug Levels and Reducing Immunogenicity in IBD. Journal of Clinical Medicine. 2023; 12(13):4382.

Chicago/Turabian Style

Demase, Kathryn, Cassandra K. Monitto, Robert D. Little, and Miles P. Sparrow. 2023. "The Role of Low-Dose Oral Methotrexate in Increasing Anti-TNF Drug Levels and Reducing Immunogenicity in IBD" Journal of Clinical Medicine 12, no. 13: 4382.

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop