A Case Report of Immunosuppressant Medication‒Associated Polyarticular Tophaceous Gout Successfully Treated Using the Polyethylene Glycol‒Conjugated Uricase Enzyme Pegloticase

Pegloticase co-administered with high MW polyethylene glycol effectively reduces PEG-immunogenicity and restores prolonged circulation in mouse

The interactions between polymers and the immune system remains poorly controlled. In some instances, the immune system can produce antibodies specific to polymer constituents. Indeed, roughly half of pegloticase patients without immunomodulation develop high titers of anti-PEG antibodies (APA) to the PEG polymers on pegloticase, which then quickly clear the drug from circulation and render the gout treatment ineffective. Here, using pegloticase as a model drug, we show that addition of high molecular weight (MW) free (unconjugated) PEG to pegloticase allows us to control the immunogenicity and mitigates APA induction in mice. Compared to pegloticase mixed with saline, mice repeatedly dosed with pegloticase containing different MW or amount of free PEG possessed 4- to 12- fold lower anti-PEG IgG, and 6- to 10- fold lower anti-PEG IgM, after 3 rounds of pegloticase dosed every 2 weeks. The markedly reduced APA levels, together with competitive inhibition by free PEG, restored the prolonged circulation of pegloticase to levels observed in APA-naïve animals. In contrast, mice with pegloticase-induced APA eliminated nearly all pegloticase from the circulation within just four hours post-injection. These results support the growing literature demonstrating free PEG may effectively suppress drug-induced APA, which in turn may offer sustained therapeutic benefits without requiring broad immunomodulation. We also showed free PEG effectively blocked the PEGylated protein from binding with cells expressing PEG-specific B cell receptors. It provides a template of how we may be able to tune the interactions and immunogenicity of other polymer-modified therapeutics. STATEMENT OF SIGNIFICANCE: A major challenge with engineering materials for drug delivery is their interactions with the immune system. For instance, our body can produce high levels of anti-PEG antibodies (APA). Unfortunately, the field currently lack tools to limit immunostimulation or overcome pre-existing anti-PEG antibodies, without using broad immunosuppression. Here, we showed that simply introducing free PEG into a clinical formulation of PEG-uricase can effectively limit induction of anti-PEG antibodies, and restore their prolonged circulation upon repeated dosing. Our work offers a readily translatable method to safely and effectively restore the use PEG-drugs in patients with PEG-immunity, and provides a template to use unconjugated polymers with low immunogenicity to regulate interactions with the immune system for other polymer-modified therapeutics.

Pegloticase in Uncontrolled Gout: The Infusion Nurse Perspective

Infused biologics, such as pegloticase, are a core component of managing uncontrolled gout, which is increasing in prevalence. Pegloticase is often the last line of therapy for patients with uncontrolled gout; therefore, achieving a successful course of treatment is critical. The infusion nurse's role in patient education, serum uric acid monitoring, and patient medication compliance is essential for ensuring patient safety and maximizing the number of patients who benefit from a full treatment course of pegloticase. Infusion nurses are on the front lines with patients and need to be educated on potential negative effects associated with the medications they infuse, such as infusion reactions, as well as risk management methods like patient screening and monitoring. Further, patient education provided by the infusion nurse plays a large role in empowering the patient to become their own advocate during pegloticase treatment. This educational overview includes a model patient case for pegloticase monotherapy, as well as one for pegloticase with immunomodulation and a step-by-step checklist for infusion nurses to refer to throughout the pegloticase infusion process. A video abstract is available for this article at http://links.lww.com/JIN/A105.

Coadministration of Immunosuppressant Treatments With Pegloticase in the Context of Solid-Organ Transplantation and Gout: A Case Report

Refractory gout can be treated with infusions of pegloticase, which metabolizes uric acid into a product readily excreted in urine. Antidrug antibodies often develop, leading to reduced efficacy and potential infusion reactions. The concomitant administration of immunosuppressive agents has been suggested as a means of mitigating the effects of drug-related immunogenicity, rendering treatment more tolerable, and resulting in better outcomes. This report presents cases of 2 patients with tophaceous gout, each having previously undergone a solid-organ transplant, each taking immunosuppressants to prevent organ rejection, and each successfully treated with pegloticase. Although data from randomized controlled studies are needed, these cases suggest that it may be beneficial to coadminister an immunosuppressive medication to extend drug persistence with pegloticase in the management of refractory gout. This approach could allow patients to receive long-term treatment, resulting in improved patient outcomes.

Enhancing the Response Rate to Recombinant Uricases in Patients with Gout

Refractory, or uncontrolled, gout is a chronic, progressive, inflammatory arthropathy resulting from continued urate deposition after failed attempts to lower serum uric acid below the therapeutic threshold with oral urate-lowering therapies such as allopurinol and febuxostat. Recombinant uricase is increasingly being used to treat refractory gout; however, the immunogenicity of uricase-based therapies has limited the use of these biologic therapies. Antidrug antibodies against biologic therapies, including uricase and PEGylated uricase, can lead to loss of urate-lowering response, increased risk of infusion reactions, and subsequent treatment failure. However, co-therapy with an immunomodulator can attenuate antidrug antibody development, potentially increasing the likelihood of sustained urate lowering, therapy course completion, and successful treatment outcomes. This review summarizes evidence surrounding the use of immunomodulation as co-therapy with recombinant uricases.

Expert Opinion on Pegloticase with Concomitant Immunomodulatory Therapy in the Treatment of Uncontrolled Gout to Improve Efficacy, Safety, and Durability of Response

PURPOSE OF REVIEW

Gout is a systemic disease from which some patients develop numerous painful tophi that adversely affect quality of life and functionality. Some patients treated with oral urate-lowering therapy are unable to maintain serum urate levels below 6 mg/dL, and these patients, thus classified as having refractory or uncontrolled gout, often require therapy with pegloticase to reduce symptoms and tophaceous burden. The objective of this expert opinion review is to summarize the available evidence supporting the use of concomitant immunomodulators with pegloticase to prevent development of anti-drug antibodies (ADAs) when treating patients with uncontrolled gout.

RECENT FINDINGS

Emerging evidence suggests that adding an immunomodulator to pegloticase therapy can substantially increase response rates to double those observed in phase 3 randomized controlled trials. The combination of immunomodulation with pegloticase should be considered in routine clinical practice to improve durability of response, efficacy, and safety among patients with uncontrolled gout who otherwise have limited therapeutic options.

Treatment advances in gout

The purpose of gout treatment is to alleviate symptoms of flares, prevent flares from recurring by lowering serum urate, and minimize structural joint damage and functional impairment. In recent years, several new medications to treat gout have been developed, and novel agents continue to be investigated, in addition to several long-established treatments. Although a number of effective therapies are available, optimal management and outcomes are frequently not achieved due to physician under prescribing of urate-lowering therapy (ULT) and poor adherence with therapy when it is prescribed. This article reviews recent developments in the management of gout with reference to recently published clinical guidelines, outlines some important questions regarding the safety and efficacy of particular agents, and remaining gaps in our knowledge about the most effective strategies for using currently available treatments.

The effect of immunomodulators on the efficacy and tolerability of pegloticase: a systematic review

INTRODUCTION

Pegloticase is a recombinant PEGylated uricase that converts relatively insoluble urate to highly water-soluble allantoin, which is readily excreted by the kidneys. It is the first and only biologic treatment indicated for refractory or uncontrolled gout. Clinical trials showed a 6-month pegloticase responder rate of 42%, with the non-responder rate largely being attributed to the development of high-titer anti-drug antibodies (ADAs) against pegloticase. Immunomodulation attenuates ADA formation to biologics in a number of autoimmune conditions, but their use with pegloticase for uncontrolled gout is less established. This systematic review examined published cases of refractory gout patients treated with immunomodulation in combination with pegloticase.

METHODS

Published cases of immunomodulation with pegloticase were identified in a PubMed search and in abstract databases of major rheumatology society meetings (2012-2020). Duplicate and review articles were excluded, as were those that did not include cases of pegloticase use with immunomodulation. Cases with off-label pegloticase administration schedules were also excluded. Pegloticase response was defined according to each study's specified standard.

RESULTS

Ten publications describing 82 cases of pegloticase use in the setting of immunomodulation were identified. Overall pegloticase response rate was 82.9%. Patients co-treated with an individual immunomodulator had the following response rates: methotrexate: 87.5% (35 of 40 patients), mycophenolate mofetil: 86.4% (19 of 22 patients vs. pegloticase monotherapy [placebo]: 40% [4 of 10 patients]), azathioprine: 63.6% (7 of 11 patients), and leflunomide: 66.7% (4 of 6 patients). A single patient was co-treated with cyclosporin and was a responder. The two patients treated with more than one immunomodulator were both responders.

CONCLUSION

Published reports suggest that immunomodulation co-therapy has the potential to markedly improve pegloticase responder rates in patients with uncontrolled gout.

Pegloticase in Combination With Methotrexate in Patients With Uncontrolled Gout: A Multicenter, Open-label Study (MIRROR)

OBJECTIVE

To examine the efficacy and safety of pegloticase in combination with methotrexate (MTX) in patients with uncontrolled gout in an exploratory, open-label clinical trial (ClinicalTrials.gov: NCT03635957) prior to a randomized, controlled trial.

METHODS

A multicenter, open-label efficacy and safety study of pegloticase with MTX co-treatment was conducted in patients with uncontrolled gout. Patients were administered oral MTX (15 mg/week) and folic acid (1 mg/day) 4 weeks prior to and throughout pegloticase treatment. The primary study outcome was the proportion of responders, defined as serum uric acid (sUA) < 6 mg/dL for ≥ 80% of the time during Month 6 (Weeks 20, 22, and 24). All analyses were performed on a modified intent-to-treat population, defined as patients who received ≥ 1 pegloticase infusion.

RESULTS

Seventeen patients were screened and 14 patients (all men, average age 49.3 ± 8.7 years) were enrolled. On Day 1, mean sUA was 9.2 ± 2.5 mg/dL, and 12 of the 14 patients had visible tophi. At the 6-month timepoint, 11/14 (78.6%, 95% CI 49.2-95.3%) met the responder definition, with 3 patients discontinuing after meeting protocol-defined treatment discontinuation rules (preinfusion sUA values > 6 mg/dL at 2 consecutive scheduled visits). All patients tolerated MTX. No new safety concerns were identified.

CONCLUSION

In this study, an increased proportion of patients maintained therapeutic response at 6 months when treated concomitantly with MTX and pegloticase as compared to the previously reported 42% using pegloticase alone. These results support the need for a randomized study of MTX or placebo with pegloticase to validate these open-label findings.

Increased Efficacy and Tolerability of Pegloticase in Patients With Uncontrolled Gout Co-Treated With Methotrexate: A Retrospective Study

INTRODUCTION

Gout is a painful inflammatory condition caused by chronically elevated serum uric acid levels (sUA). When standard urate-lowering therapies fail/are not tolerated, uncontrolled gout (elevated sUA, subcutaneous tophi, chronic gouty arthritis, frequent flares) can occur. Pegloticase, a recombinant uricase, converts uric acid to allantoin, a readily excreted molecule. Responder rate in trials was 42%, limited by anti-drug antibody (ADA) development. Immunomodulators attenuate ADA formation and case reports suggest immunomodulation increases pegloticase responder rates. The current study retrospectively examined responder rate in patients undergoing methotrexate/pegloticase co-therapy.

METHODS

Patients who underwent methotrexate/pegloticase co-treatment at a single rheumatology practice were included. Demographics, clinical, treatment, and safety parameters were collected. The primary outcome was the proportion of responders (≥ 12 biweekly pegloticase infusions, sUA < 6 mg/dl just prior to infusion 12).

RESULTS

Ten patients (nine men, 52.3 ± 13.5 years) with uncontrolled tophaceous gout (erosive damage, ulcerative tophi, frequent flares, gout-related hospitalizations) were included. Patients had failed allopurinol (100-300 mg) or febuxostat (40 mg) therapy (doses not increased because of intolerance, kidney concerns, noncompliance, or rapid tophi resolution requirement). Baseline sUA was 9.42 ± 2.05 mg/dl. Along with standard pre-infusion prophylaxis, nine patients received subcutaneous methotrexate (25 mg/week) initiated 14-35 days before pegloticase and one patient received oral methotrexate (12.5 mg/week) initiated 14 days after pegloticase. Eight patients (80%) were responders, receiving 15.5 ± 3.8 infusions (range, 12-21) over 31.8 ± 9.5 weeks. One patient had efficacy loss with mild infusion reaction during infusion 4 and one patient was lost to follow-up after infusion 5. One patient reported one gout flare. No new safety concerns emerged.

CONCLUSIONS

Methotrexate/pegloticase co-therapy resulted in a higher responder rate than the established 42% with pegloticase alone. Therefore, methotrexate/pegloticase co-therapy may safely allow more patients to benefit from a full treatment course, likely through ADA attenuation.

Pharmacokinetics of Polyethylene Glycol-Modified Canine Uricase Following Single and Multiple Intravenous Injections in Cynomolgus Monkeys

BACKGROUND AND OBJECTIVE

Polyethylene glycol-modified canine uricase (PEG-UHC) prepared with a lower-molecular-weight (5 kDa) PEG is used to treat gout. This study investigated the comparative pharmacokinetics of single and multiple doses of PEG-UHC administered intravenously and a single dose of uricase (UHC) administered intravenously in cynomolgus monkeys.

METHODS

A noncompartmental model was used to fit the plasma drug concentration-time curve and calculate the pharmacokinetic parameters of PEG-UHC, which were compared with those obtained for UHC at the equivalent dose (2 mg/kg). To study the pharmacokinetics after multiple dose administration, cynomolgus monkeys were administered five intravenous injections of PEG-UHC (0.5 mg/kg), with one injection performed every 15 days.

RESULTS

The area under the curve (AUC) and the maximum plasma concentration (C_max) of PEG-UHC were positively correlated with dose, whereas plasma half-life (t_1/2) and clearance (CL) did not change significantly with increasing dose, suggesting that these pharmacokinetic characteristics are linear. Intravenous PEG-UHC exhibited an average t_1/2 that was 125.79 times longer and an AUC_0-t that was 64.45 times larger than the corresponding values for UHC at the same dose (2 mg/kg), while the CL of PEG-UHC was 1/72.73 times the CL of intravenous UHC. The plasma drug concentration reached a steady state after five injections, and the t_1/2 values following the first and last drug administration did not differ significantly.

CONCLUSION

Our data show that PEG-UHC is markedly superior to UHC in terms of duration of action, and that the pharmacokinetics of PEG-UHC in cynomolgus monkeys are linear. Sequential administration of PEG-UHC did not accelerate drug clearance. Our findings provide the basis for future clinical studies of PEG-UHC.

Comparison of Two Corticosteroid Pre-Infusion Regimens for Pegloticase in the United States: A Retrospective Analysis in Community Rheumatology Practices

BACKGROUND

Pegloticase is a recombinant porcine-like uricase enzyme that is FDA-approved for the treatment of chronic refractory gout in adults. Some patients receiving pegloticase develop anti-drug antibodies, which leads to both loss of pegloticase efficacy and an increased risk for infusion reactions. In the pivotal trials, all patients received pre-infusion medications before each pegloticase dose, including intravenous (IV) hydrocortisone. In clinical practice, many clinicians use methylprednisolone for pre-infusion therapy with pegloticase; however, the efficacy of methylprednisolone compared with hydrocortisone as a pre-infusion medication for pegloticase has not been established.

OBJECTIVE

The aim of this study was to compare the efficacy of methylprednisolone versus hydrocortisone as a pre-infusion medication for pegloticase.

METHODS

Data were retrospectively collected from 92 qualifying patients treated with pegloticase and administered pre-infusion prophylaxis with either intravenous hydrocortisone or methylprednisolone. Patient demographics, steroid type and dose, duration of pegloticase therapy, overall number of infusions, and number of infusion reactions were assessed.

RESULTS

Patients treated with methylprednisolone as a pre-infusion medication received on average 8.5 pegloticase infusions versus 4.9 infusions for patients who were treated with hydrocortisone (p < 0.001). In addition, a significantly lower proportion of patients receiving methylprednisolone had their course of therapy terminated early due to infusion reactions (8.2%) versus patients receiving hydrocortisone (41.9%, p < 0.01).

CONCLUSION

In this retrospective chart-review project, patients were able to have a longer duration of pegloticase therapy, received a significantly greater number of infusions, and experienced fewer infusion reactions when methylprednisolone was used as the corticosteroid for pre-infusion prophylaxis compared with hydrocortisone.

Recapture and improved outcome of pegloticase response with methotrexate-A report of two cases and review of the literature

INTRODUCTION

Pegloticase is a PEGylated uric acid specific enzyme indicated for the treatment of refractory gout. Anti-pegloticase antibodies contribute to high discontinuation rates, increased risk of infusion reactions, and early loss of drug efficacy.

OBJECTIVE

To describe the use of methotrexate to recapture function of pegloticase after development of anti-drug antibodies while treating gout.

METHODS

We report two cases of using methotrexate as an adjunct to treatment with pegloticase for refractory tophaceous gout. We also present the results of a literature review on the use of concomitant immunosuppressive therapy with pegloticase to prevent anti-pegloticase antibody development.

RESULTS

Patient A, a 55-year-old man with a history of tophaceous gout, was treated with pegloticase but developed high serum urate(sUA) levels prior to his third infusion. Adjunctive treatment with methotrexate restored pegloticase response and the patient's sUA levels decreased, and remained low for the remainder of his treatment. Patient B, a 36-year-old man with a history of tophaceous gout, was treated with pegloticase. Oral methotrexate was initiated at the first infusion. Low sUA levels were achieved but increased after a lapse in methotrexate compliance. Re-initiation of methotrexate restored pegloticase response and the patient tolerated subsequent infusions. Literature review identified three reports of successful use of concomitant pegloticase and immunosuppressive therapy for refractory tophaceous gout, including an open label trial with a subset of 7 transplant recipients, an additional case study of pegloticase treatment with one transplant recipient, and a case study of pegloticase administered with low-dose azathioprine.

CONCLUSION

Prophylactic use of immunosuppressive therapy with pegloticase may enable sustained treatment and improve outcomes. Additionally, immunosuppressive therapy seems to show the ability to recapture pegloticase response after development of anti-drug antibodies. The use of immunosuppressants to prevent anti-drug antibody formation, recapture pegloticase efficacy, and reduce discontinuation rates warrants further study.