Tapering and Discontinuation of Biologics in Patients with Psoriatic Arthritis with Low Disease Activity

EULAR recommendations for the management of psoriatic arthritis with pharmacological therapies: 2023 update

OBJECTIVE

New modes of action and more data on the efficacy and safety of existing drugs in psoriatic arthritis (PsA) required an update of the EULAR 2019 recommendations for the pharmacological treatment of PsA.

METHODS

Following EULAR standardised operating procedures, the process included a systematic literature review and a consensus meeting of 36 international experts in April 2023. Levels of evidence and grades of recommendations were determined.

RESULTS

The updated recommendations comprise 7 overarching principles and 11 recommendations, and provide a treatment strategy for pharmacological therapies. Non-steroidal anti-inflammatory drugs should be used in monotherapy only for mild PsA and in the short term; oral glucocorticoids are not recommended. In patients with peripheral arthritis, rapid initiation of conventional synthetic disease-modifying antirheumatic drugs is recommended and methotrexate preferred. If the treatment target is not achieved with this strategy, a biological disease-modifying antirheumatic drug (bDMARD) should be initiated, without preference among modes of action. Relevant skin psoriasis should orient towards bDMARDs targeting interleukin (IL)-23p40, IL-23p19, IL-17A and IL-17A/F inhibitors. In case of predominant axial or entheseal disease, an algorithm is also proposed. Use of Janus kinase inhibitors is proposed primarily after bDMARD failure, taking relevant risk factors into account, or in case bDMARDs are not an appropriate choice. Inflammatory bowel disease and uveitis, if present, should influence drug choices, with monoclonal tumour necrosis factor inhibitors proposed. Drug switches and tapering in sustained remission are also addressed.

CONCLUSION

These updated recommendations integrate all currently available drugs in a practical and progressive approach, which will be helpful in the pharmacological management of PsA.

The Saudi consensus recommendations for the management of psoriatic arthritis (2023)

Psoriatic arthritis (PsA) is a complex inflammatory disease characterized by musculoskeletal and non-musculoskeletal manifestations. It is a distinct disease entity at the interface between rheumatology and dermatology, making it challenging to manage. The diverse clinical presentation and severity of PsA require a multidisciplinary approach for optimal care. Early diagnosis and management are necessary to improving quality of life for patients. In Saudi Arabia, there is currently no unified national consensus on the best practices for managing PsA. This lack of consensus leads to debate and uncertainty in the treatment of the disease, resulting in over or under prescribing of biological agents. To address this issue, a multidisciplinary work group was formed by the Saudi Ministry of Health. This group, consisting of dermatologists, rheumatologists, and pharmacists, aimed to develop evidence-based consensus recommendations for he use and monitoring of biological therapy in PsA management. The work group conducted five consensus workshops between December 2021 to March 2022. Using the nominal group technique, they discussed various aspects of PsA management, including eligibility criteria for biological treatment, monitoring of disease activity, treatment goals, screening, precautions, and management of PsA with biologic therapies. The group also considered special considerations for patients with comorbidities, pregnant and lactating women, as well as pediatric and adolescent populations. The resulting consensus document provides recommendations that are applicable to the Saudi setting, taking into account international guidelines and the specific needs of PsA patients in the country. The consensus document will be regularly updated to incorporate new data and therapeutic agents as they become available. Key Points • In Saudi Arabia, there is a lack of unified national consensus on the optimal management of PsA, therefore, this article aims to provide up-to-date evidence-based consensus recommendations for the optimal use and monitoring of biologic therapy in the management of PsA in Saudi Arabia. • The consensus development process was undertaken by a multidisciplinary work group of 13 experts, including two dermatologists, six rheumatologists, and five pharmacists. • There is more than one disease activity tool used in PsA disease, depending on the disease domain - peripheral arthritis Disease Activity Index in Psoriatic Arthritis (DAPSA) or Minimal Disease Activity (MDA), axial PsA Ankylosing Spondylitis Disease Activity Score (ASDAS), and dactylitis and enthesitis MDA. • The main goal of therapy in all patients with PsA is to achieve the target of remission, or alternatively, low disease activity in all disease domains and improve quality of life (QoL).

Disease activity-guided tapering of biologics in patients with inflammatory arthritis: a pragmatic, randomized, open-label, equivalence trial

OBJECTIVE

To evaluate whether disease activity-guided tapering of biologics compared to continuation as usual care enables a substantial dose reduction while disease activity remains equivalent.

METHOD

In this pragmatic, randomized, open-label, equivalence trial, adults with rheumatoid arthritis, psoriatic arthritis, or axial spondyloarthritis in low disease activity on stable-dose biologics for ≥ 12 months were randomized 2:1 into either the tapering group, i.e. disease activity-guided prolongation of the biologic dosing interval until flare or withdrawal, or the control group, i.e. maintaince of baseline biologics with a possible small interval increase at the patients request. The co-primary outcome in the intention-to-treat population was met if superiority in ≥ 50% biologic reduction at 18 months was demonstrated and disease activity was equivalent (equivalence margins ± 0.5).

RESULTS

Ninety-five patients were randomized to tapering and 47 to control, of whom 37% (35/95) versus 2% (1/47) achieved ≥ 50% biologic reduction at 18 months. The risk difference was statistically significant [35%, 95% confidence interval (CI) 24%-45%], while disease activity remained equivalent [mean difference 0.05, 95% CI -0.12-0.29]. A statistically significant flare risk was observed [tapering 41% (39/95) vs control 21% (10/47), risk difference 20%, 95% CI 4%-35%]; but, only 1% (1/95) and 6% (3/47) had persistent flare and needed to switch to another biological drug.

CONCLUSIONS

Disease activity-guided tapering of biologics in patients with inflammatory arthritis enabled one-third to achieve ≥ 50% biologic reduction, while disease activity between groups remained equivalent. Flares were more frequent in the tapering group but were managed with rescue therapy.

Managing psoriatic arthritis in different clinical scenarios

INTRODUCTION

Psoriatic arthritis (PsA) is a chronic, immune-mediated disease characterized by synovio-entheseal inflammation. It is estimated to affect around 30% of patients with psoriasis and significantly reduces patients' physical function and quality of life. There is a growing number of treatment options for PsA, but due to the heterogeneous clinical features of the disease and prevalence of comorbidities, managing PsA can be challenging.

AREAS COVERED

In this article, we review current understanding of the disease and available pharmacological options. Based on published treatment guidelines, emerging evidence and clinical experience, we provide our expert opinion on treatment strategies, taking into consideration the predominant disease domain and the presence of comorbidities, which can impact treatment decisions and clinical outcomes.

EXPERT OPINION

Biological and targeted synthetic disease-modifying agents are dramatically improving the lives of patients with PsA. Biosimilar TNF inhibitors offer a particularly versatile and cost-effective option, whilst newer biologics and targeted synthetic molecules that can be used to treat most domains of psoriatic disease are an attractive alternative to TNF inhibitors. Despite a lack of consensus on treatment sequencing and tapering, it is important that PsA patients, especially those with comorbidities, are looked after by a multidisciplinary team to optimize their care.

Interval prolongation of etanercept in rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis: a randomized controlled trial

OBJECTIVE

The majority of patients with a rheumatic disease treated with etanercept may be overexposed. Data regarding etanercept tapering are scarce, particularly in psoriatic arthritis (PsA) and ankylosing spondylitis (AS). We compared extending the dose interval to continuation of the standard dose and studied the success rate of etanercept discontinuation. Etanercept concentrations were measured throughout the study.

METHOD

160 patients with rheumatoid arthritis (RA), PsA, or AS with sustained minimal disease activity (MDA) were enrolled in this 18-month, open-label, randomized controlled trial. The intervention group doubled the dosing interval at baseline and discontinued etanercept 6 months later. The control group continued the standard dose for 6 months and doubled the dosing-interval thereafter. The primary outcome was the proportion of patients maintaining MDA at 6 month follow-up.

RESULTS

At 6 months, MDA status was maintained in 47 patients (63%) in the intervention group and 56 (74%) in the control group (p = 0.15), with comparable results in all rheumatic diseases. And median etanercept concentrations decreased from 1.50 µg/mL (interquartile range 1.06- 2.65) to 0.46 µg/mL (0.28-0.92). In total, 40% discontinued etanercept successfully with maintained MDA for at least 6 months.

CONCLUSION

Etanercept tapering can be done without losing efficacy in RA, PsA, and AS patients in sustained MDA. A substantial proportion of patients could stop etanercept for at least 6 months. In many patients, low drug concentrations proved sufficient to control disease activity. However, the risk of minor and major flares is substantial, even in patients continuing standard dosing.

The second decade of anti-TNF-a therapy in clinical practice: new lessons and future directions in the COVID-19 era

Since the late 1990s, tumor necrosis factor alpha (TNF-α) inhibitors (anti-TNFs) have revolutionized the therapy of immune-mediated inflammatory diseases (IMIDs) affecting the gut, joints, skin and eyes. Although the therapeutic armamentarium in IMIDs is being constantly expanded, anti-TNFs remain the cornerstone of their treatment. During the second decade of their application in clinical practice, a large body of additional knowledge has accumulated regarding various aspects of anti-TNF-α therapy, whereas new indications have been added. Recent experimental studies have shown that anti-TNFs exert their beneficial effects not only by restoring aberrant TNF-mediated immune mechanisms, but also by de-activating pathogenic fibroblast-like mesenchymal cells. Real-world data on millions of patients further confirmed the remarkable efficacy of anti-TNFs. It is now clear that anti-TNFs alter the physical course of inflammatory arthritis and inflammatory bowel disease, leading to inhibition of local and systemic bone loss and to a decline in the number of surgeries for disease-related complications, while anti-TNFs improve morbidity and mortality, acting beneficially also on cardiovascular comorbidities. On the other hand, no new safety signals emerged, whereas anti-TNF-α safety in pregnancy and amid the COVID-19 pandemic was confirmed. The use of biosimilars was associated with cost reductions making anti-TNFs more widely available. Moreover, the current implementation of the “treat-to-target” approach and treatment de-escalation strategies of IMIDs were based on anti-TNFs. An intensive search to discover biomarkers to optimize response to anti-TNF-α treatment is currently ongoing. Finally, selective targeting of TNF-α receptors, new forms of anti-TNFs and combinations with other agents, are being tested in clinical trials and will probably expand the spectrum of TNF-α inhibition as a therapeutic strategy for IMIDs.

Risk of flare after tapering or withdrawal of b-/tsDMARDs in patients with RA or axSpA: A systematic review and meta-analysis

OBJECTIVE

To evaluate flare risk when tapering or withdrawing biological or targeted synthetic disease-modifying antirheumatic drugs (b-/tsDMARDs) compared to continuation in patients with inflammatory arthritis (IA) in sustained remission or low disease activity.

METHODS

Articles were identified in Cochrane Library, PubMed, EMBASE and Web of Science. Eligible trials were randomised, controlled trials comparing tapering and/or withdrawal of b- and/or tsDMARDs with standard dose in IA. Random-effects meta-analysis was performed with risk ratio (RR), or Peto's Odds Ratio (POR) for sparse events, and 95% confidence intervals (95%CI).

RESULTS

The meta-analysis comprised 22 trials: 11 assessed tapering and 7 addressed withdrawal (4 assessed both). Only trials with a rheumatoid arthritis (RA) or axial spondyloarthritis (axSpA) population were identified. An increased flare risk was demonstrated when b-/tsDMARD tapering was compared to continuation, RR = 1.45 (95%CI: 1.19 to 1.77, I2 = 42.5%), and potentially increased for persistent flare, POR = 1.56 (95%CI: 0.97 to 2.52, I2 = 0%). Comparing tumour necrosis factor inhibitor (TNFi) withdrawal to continuation, a highly increased flare risk (RR = 2.28, 95%CI: 1.78 to 2.93, I2 = 78%) and increased odds of persistent flare (POR = 3.41, 95%CI: 1.91 to 6.09, I2 = 49%) was observed. No clear difference in flare risk between RA or axSpA was observed.

CONCLUSION

A high risk for flare and persistent flare was demonstrated for TNFi withdrawal whereas an increased risk for flare but not for persistent flare was observed for b-/tsDMARD tapering. Thus, tapering seems to be the more favourable approach.

REGISTRATION

PROSPERO (CRD42019136905).

Tumour necrosis factor inhibitor dose adaptation in psoriatic arthritis and axial spondyloarthritis (TAPAS): a retrospective cohort study

Objectives

We investigated the effect of disease activity-guided dose optimization (DAGDO) of TNF inhibitor (TNFi) on disease activity and TNFi dose in PsA and axial spondyloarthritis (axSpA) patients with low disease activity (LDA).

Methods

A retrospective cohort study was conducted in PsA and axSpA patients doing well on TNFi and eligible for TNFi DAGDO. Three different treatment periods were defined: (i) full dose continuation period, (ii) TNFi DAGDO period, and (iii) period with stable TNFi dose after DAGDO. A mixed-model analysis was used to estimate mean Disease Activity Score 28-joint count CRP (DAS28-CRP) and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) during these periods, and a mean percentage of the daily defined dose (%DDD) was calculated as secondary outcome.

Results

Three hundred and twenty-four patients (153 PsA and 171 axSpA) were included, with a mean of 6.5 DAS28-CRP and 6.4 BASDAI measurements and a median follow-up duration of 46 and 44 months, respectively. A corrected difference of 0.06 (95% CI: −0.09, 0.21) in mean DAS28-CRP was found for the TNFi DAGDO period and 0.03 (95% CI: −0.14, 0.20) for the period with stable TNFi dose, compared with full dose continuation period. Differences for BASDAI were 0.03 (95% CI: −0.21, 0.27) and 0.05 (95% CI: −0.24, 0.34), respectively. The mean %DDD for the three treatment periods was for PsA 108%, 62% and 78%, and for axSpA 108%, 62% and 72%, respectively.

Conclusion

DAGDO of TNFi reduces drug exposure and has no negative effects on disease activity in PsA and axSpA patients compared with full dose continuation.

Unmet needs in psoriatic arthritis

Psoriatic arthritis (PsA) is a chronic inflammatory arthritis with a highly variable clinical presentation that does not have a validated molecular or imaging test, making accurate diagnosis a challenge. Consequences of diagnostic delay include irreversible joint damage and significant morbidity. Over the past few decades, there have been major advances in the understanding and treatment of PsA, leading to more targeted therapies. However, there is no current method to predict optimal treatment strategy to achieve minimal disease activity and prevent medication-related adverse events in the management of early disease. PsA is also associated with other comorbidities that include metabolic syndrome and psychosocial burden; two areas that are often unaddressed in the clinical setting and have associated sequelae. This chapter focuses on key domains of unmet needs, which include diagnostic challenges, delay in diagnosis, prognostication systems and stratified medicine approaches and precision medicine strategies for established and emerging therapies.

IL-12p40/IL-23p40 Blockade With Ustekinumab Decreases the Synovial Inflammatory Infiltrate Through Modulation of Multiple Signaling Pathways Including MAPK-ERK and Wnt

Background: Psoriatic arthritis (PsA) is a chronic inflammatory joint disease within the spondyloarthritis spectrum. IL-12p40/IL-23p40 blockade reduces PsA disease activity, but its impact on synovial inflammation remains unclear. Objectives: To investigate the cellular and molecular pathways affected by IL-12p40/IL-23p40 blockade with ustekinumab in the synovium of PsA patients. Methods: Eleven PsA patients with at least one inflamed knee or ankle joint were included in a 24-week single-center open-label study and received ustekinumab 45 mg/sc according to standard care at week 0, 4, and 16. Besides clinical outcomes, synovial tissue (ST) samples were obtained by needle arthroscopy from an inflamed knee or ankle joint at baseline, week 12 and 24 and analyzed by immunohistochemistry, RNA-sequencing and real-time quantitative polymerase chain reaction (qPCR). Results: We obtained paired baseline and week 12, and paired baseline, week 12 and 24 ST samples from nine and six patients, respectively. Eight patients completed 24 weeks of clinical follow-up. At 12 weeks 6/11 patients met ACR20, 2/11 met ACR50 and 1/11 met ACR70 improvement criteria, at 24 weeks this was 3/8, 2/8 and 1/8 patients, respectively. Clinical and serological markers improved significantly. No serious adverse events occurred. We observed numerical decreases of all infiltrating cell subtypes at week 12, reaching statistical significance for CD68+ sublining macrophages. For some cell types this was even more pronounced at week 24, but clearly synovial inflammation was incompletely resolved. IL-17A and F, TNF, IL-6, IL-8, and IL-12p40 were not significantly downregulated in qPCR analysis of W12 total biopsies, only MMP3 and IL-23p19 were significantly decreased. RNA-seq analysis revealed 178 significantly differentially expressed genes between baseline and 12 weeks (FDR 0.1). Gene Ontology and KEGG terms enrichment analyses identified overrepresentation of biological processes as response to reactive oxygen species, chemotaxis, migration and angiogenesis as well as MAPK-ERK and PI3K-Akt signaling pathways among the downregulated genes and of Wnt signaling pathway among the upregulated genes. Furthermore, ACR20 responders and non-responders differed strikingly in gene expression profiles in a post-hoc exploratory analysis. Conclusions: Ustekinumab suppresses PsA synovial inflammation through modulation of multiple signal transduction pathways, including MAPK-ERK, Wnt and potentially PI3K-Akt signaling rather than by directly impacting the IL-17 pathway.

Dose Tapering of Biologics in Patients with Psoriasis: A Scoping Review

Introduction

Biologics serve as a cornerstone in psoriasis treatment, with low disease activity or sometimes even clinical remission as a realistic treatment outcome. So far, it is unclear whether biologics should be tapered when this target is achieved. Dose tapering could offer potential benefits by decreasing side effects, the burden of repetitive injections and costs of biological therapy. However, clinical guidelines on dose tapering of biologicals in psoriasis patients are lacking. This scoping review was conducted to provide an overview of the current literature on dose tapering and offer guidance for clinicians in daily clinical practice.

Methods

Dose tapering is defined as the administration of a lower dose per administration, or the prolongation of the regular dose interval, after initial treatment according to the standard dosing. Four electronic databases (PubMed, EMBASE, Cochrane, and Web of Science) were systematically searched for literature on tapering of biologics in adult patients with psoriasis from 1 January 2000.

Results

We included 19 original articles on biologic tapering in psoriasis patients: four randomized controlled trials and 15 observational studies. Tapering eligibility criteria, tapering strategies, tapering outcomes, and recapture of response after relapse were assessed. Furthermore, the available evidence on possible predictors for successful tapering, and the effect of tapering on safety, quality of life and costs is summarized. The definition of low disease activity as a measure for tapering eligibility varied widely. Beside tapering criteria, tapering strategies were also heterogeneous. Of note, quality-of-life measurements were barely integrated in the evaluation of tapering outcomes. Literature on regaining response after relapse due to tapering was limited, but restored remission has been described. The included studies did not proclaim a significant effect of tapering on the occurrence of (severe) adverse events. Even though cost savings have been reported, no proper cost-effectiveness analysis has been conducted yet.

Conclusion

Biologic tapering seems to be effective and safe in psoriasis patients with stable low disease activity or clinical remission. Available data on biologic dose tapering in patients with psoriasis are promising, but more research is warranted to fill the current gaps in knowledge.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40265-020-01448-z.

Biologics are effective in treating psoriasis amongst other diseases, such as rheumatoid arthritis and Crohn’s disease. However, biologics are costly, and can cause side effects, such as an increased risk of infection. In patients with rheumatoid arthritis, it is not uncommon to lower the dose of these biologics (also called “dose tapering”), once stable low disease activity, or even remission, is reached. However, in psoriasis patients, dose tapering of biologics is not common practice. In this “scoping review,” we provide an overview of the available literature on dose tapering of biologics in adult patients with plaque psoriasis in order to address the current gaps in literature. We found 19 studies that addressed dose tapering. These studies used different criteria to determine which patients were eligible for tapering, which led to various interpretations of tapering success. This made it difficult for us to draw general conclusions on which tapering criteria and strategies should be further investigated. Dose tapering seems to be effective and safe in patients with a stable low disease activity, although more (high-quality) research is needed. Future studies should focus on generating more data on long-term safety, finding predictors for successful tapering, calculating the cost-effectiveness of dose tapering, and evaluating dose tapering in the newest generation of biologics.

Unlocking the Value of Anti-TNF Biosimilars: Reducing Disease Burden and Improving Outcomes in Chronic Immune-Mediated Inflammatory Diseases: A Narrative Review

Immune-mediated inflammatory diseases (IMIDs) are chronic conditions that create a significant disease burden on millions of patients while adding a major financial burden to societies and healthcare systems.

The introduction of biologic medicines has contributed majorly to improving the clinical outcomes of IMIDs and as such these modalities have gained first- or second-line positions in a wide range of treatment guidelines from different international clinical societies. However, the high cost of these biologics traditionally limited their accessibility and delayed their initiation, leaving millions of patients with unmet medical needs for a more affordable and sustainable solution.

The introduction of cost-efficient biosimilar anti-TNFs within Europe since 2013 has allowed more patients with IMIDs to access biologic therapies earlier and for longer, potentially altering the course of the disease into a milder phenotype and reducing the long-term disease burden. This review provides the latest evidence for the impact of biosimilars on patient outcomes and demonstrates their clinical value beyond a reduction in price.

Treatment Withdrawal Following Remission in Juvenile Idiopathic Arthritis: A Systematic Review of the Literature

BACKGROUND

Early diagnosis and treatment of juvenile idiopathic arthritis (JIA) with conventional and biologic disease-modifying anti-rheumatic drugs have vastly improved outcomes for children with these diseases. Currently, a large proportion of children with JIA are able to achieve clinical inactive disease and remission. With this success, important questions have arisen about when medications can be stopped and how to balance the risks and benefits of continuing medications versus the potential for flare after stopping.

AIM

The aim was to conduct a systematic review of the available literature to summarize current evidence about medication withdrawal for JIA in remission.

METHODS

We conducted a systematic literature search in PubMed and Embase from 1990 to 2019. References were first screened by title and then independently screened by title and abstract by two authors. A total of 77 original papers were selected for full-text review. Data were extracted from 30 papers on JIA and JIA-associated uveitis, and the quality of the evidence was evaluated using National Institutes of Health (NIH)/National Heart, Lung, and Blood Institute (NHLBI) tools. Studies on biochemical and radiologic biomarkers were also reviewed and summarized.

RESULTS

Most studies investigating treatment withdrawal in JIA have been observational and of poor or fair quality; interpretations of these studies have been limited by differences in study populations, disease and remission durations, the medications withdrawn, approaches to withdrawal, and definitions of disease outcomes. Overall the data suggest that flares are common after stopping JIA medications, particularly biologic medications. Clinical characteristics associated with increased risks of flare have not been consistently identified. Biochemical biomarkers and ultrasound findings have been shown to predict outcomes after stopping medications, but to date, no such predictor has been consistently validated across JIA populations. Studies have also not identified optimal strategies for withdrawing medication for well-controlled JIA. Promising withdrawal strategies include discontinuing methotrexate before biologic medications in children receiving combination therapy, dose reduction for children on biologics, and treat-to-target approaches to withdrawal. These and other strategies require further investigation in larger, high-quality studies.

CONCLUSIONS

The published literature on treatment withdrawal in JIA has varied in design and quality, yielding little conclusive evidence thus far on the management of JIA in remission. Given the importance of this question, international collaborative efforts are underway to study clinical and biologic predictors of successful medication withdrawal in JIA. These efforts may ultimately support the development of personalized approaches to withdrawing medication in children with JIA in remission.

Can we wean patients with inflammatory arthritis from biological therapies?

Biological therapies have represented a cornerstone in the treatment of immune-mediated inflammatory diseases. Their advent combined with implementation of a treat-to-target approach has meant that remission or low disease activity are now realistic targets for treatment achieved by a significant number of patients. However, biologicals are not risk free and their elevated costs continue to present an important economic burden to national healthcare services. "Can we wean patients with inflammatory arthritis from biological therapies?" Over the last decade this question has become increasingly important as to define the best management strategies in terms of efficacy, safety and economic outcomes. Not surprisingly this has generated an interesting debate as to whether reasons to taper biologics outweigh reasons not to taper and evidence in support of either of these schools of thought is persistently growing. AIM: In this article we reviewed the contents of the relevant session from the 2019 Controversies in Rheumatology and Autoimmunity meeting in Florence.

Biological and synthetic target DMARDs in psoriatic arthritis

Psoriatic arthritis (PsA) is a chronic multi-faceted immune-mediated systemic disorder, characterized by articular, cutaneous, enthesis, nail and spine involvement. Articular manifestations of PsA are particularly common and highly disabling for patients, while the heterogeneous clinical subsets of the disease are challenging for clinicians. In recent years, research has made many advances in understanding the pathogenesis of the disease from genetic, epigenetic and molecular points of view. New drugs are now available for the treatment of this condition, and, in particular, TNF-alfa inhibitors, historically the first biologicals approved in PsA, are now juxtaposed by new biological disease modifying anti-rheumatic drugs (bDMARDs) with different modes of action. Targeting IL-12/IL-23 p40 common subunit with ustekinumab, IL-17A with secukinumab and ixekizumab, T cells co-stimulation with abatacept, is now possible, safe and effective. Moreover, targeted synthetic molecules with oral administration are available, with the possibility to interfere with phosphodiesterase-4 and JAK/STAT pathways. Indeed, new drugs are under development, with the possibility to target selectively IL-17 receptor, IL-23, and other key molecular targets in the pathogenesis of this condition. In this narrative review, we provide an up-to-date overview of the current application of biological and targeted synthetic DMARDs in the field of PsA, with particular regard to the clinical significance of this possibility to target a higher number of distinct immune-pathways.

Systemic rheumatic diseases: From biological agents to small molecules

The development of biologics and small oral molecules has recently changed the scenario of pharmacologic treatment of systemic rheumatic diseases and it has become a real revolution. These drugs have innovative mechanisms of action, based on the inhibition of specific molecular or cellular targets directly involved in disease pathogenesis. This new scenario has lead to a regular update of the management recommendations of several institutions, such as those for Rheumatoid Arthritis treatment that address the use of conventional and biologic therapies including TNF inhibitors (adalimumab, certolizumab pegol, etanercept, golimumab, infliximab), abatacept, rituximab, IL-6 inhibitors (tocilizumab and sarilumab), biosimilars and small oral molecules (the JAK inhibitors tofacitinib and baricitinib). Monotherapy, combination therapy, treatment strategies (such as treat-to-target) and the targets of sustained clinical remission or low disease activity are the final goal of the guidelines for rheumatic patients management. In another condition represented by Axial Spondyloarthritis guidelines suggest to start first with non-steroidal anti-inflammatory drugs to improve lifestyle and reduce spine inflammation, but if this is not achieved in 2-4 weeks it is important to consider the use of local therapies (i.e. glucocorticoid injections) or to start biologic therapy such as TNF inhibitors and then eventually switching to another TNF inhibitor or swapping to IL-17 inhibitor. In the case of active Psoriatic Arthritis, guidelines suggest to start with non-steroidal anti-inflammatory drugs and even local glucocorticoid injections especially for oligoarthritis, then to start conventional therapies if lack of efficacy, and finally start biologics or small oral molecules in the presence of drugs toxicity, unfavorable prognostic factors and still active arthritis. In several cases, active Psoriatic Arthritis patients develop a complex clinical condition with comorbidities such as diabetes, inflammatory bowel disease and high risk of infections, and for this reason the American College of Rheumatology and the National Psoriasis Foundation have developed specific guidelines for their management. Biologic and new small molecules therapies are very expensive, but the availability of biosimilars offers the opportunity of reducing the treatment cost and significantly decreasing the cost of originators as well. In fact, we live in a period characterized by the need to rationalize costs of these drugs, to allow treating a higher number of patients and to maintain a homogeneous possibility of treatment choice. For these reasons, we need to follow scientific guidelines and patients' clinical conditions to choose the correct treatment, also based on the economic burden of therapies.