A Phase 4, Open-label Study of KRYSTEXXA® (Pegloticase) Co-administered With Methotrexate (MTX) in Patients With Uncontrolled Gout (FORWARD OL) (FORWARD OL)

A Phase 4, Open-Label, Multicenter, Efficacy, Safety, Pharmacokinetics and Pharmacodynamics Trial of Intravenous KRYSTEXXA® (Pegloticase) Administered Every 4 Weeks With Co-Administration of Weekly Doses of Methotrexate in Patients With Uncontrolled Refractory Gout (FORWARD Open-Label [OL] Trial)

This trial is to assess efficacy, safety, blood levels and bodily effects of up to 2 dose levels of intravenous (IV) pegloticase (KRYSTEXXA) infusions at every 4 week intervals (Q4 Weeks) for up to 6 months (Day 1 to 24 weeks with an optional 24 - 48 weeks treatment duration) when given in combination with weekly oral doses of methotrexate (MTX). The goal is to identify an appropriate dose to be administered every 4 weeks to be used for future clinical trials for patients with chronic gout that does not adequately respond to conventional therapy.

Study Overview

• Status: Completed
• Conditions: Uncontrolled Gout; Chronic Gout
• Intervention / Treatment: Biological: Pegloticase; Drug: Methotrexate (MTX)

Detailed Description

The primary objective is to choose a dose for further investigation by assessing the effect of up to 2 dose levels of pegloticase administered IV Q4 weeks, co-administered with weekly doses of oral MTX, as measured by the sustained normalization of serum uric acid (sUA) to < 6 mg/dL for at least 80% of the time during Month 6 and the duration of sUA to < 6 mg/dL over 24 week treatment period in adult participants with chronic gout refractory to conventional therapy.

Acquired from Horizon in 2024.

• Study Type: Interventional
• Enrollment (Actual): 54
• Phase: Phase 4

Contacts and Locations

Study Locations

• United States
  • Alaska
    • Anchorage, Alaska, United States, 99508
      • Orthopedic Physicians Alaska
  • Arizona
    • Glendale, Arizona, United States, 85306
      • Arizona Arthritis & Rheumatology Research, PLLC
  • California
    • San Leandro, California, United States, 94578
      • East Bay Rheumatology Medical Group, Inc.
  • Florida
    • Doral, Florida, United States, 33166
      • Prohealth Research Center
    • Pompano Beach, Florida, United States, 33064
      • Napa Research Center
    • Tampa, Florida, United States, 33064
      • GCP Clinical Research
  • Maryland
    • Wheaton, Maryland, United States, 20902
      • The Center for Rheumatology and Bone Research
  • North Carolina
    • Shelby, North Carolina, United States, 28150
      • Shelby Clinical Research, LLC
  • Pennsylvania
    • Duncansville, Pennsylvania, United States, 16635
      • Altoona Center For Clinical Research
  • Texas
    • Houston, Texas, United States, 77043
      • Biopharma Informatic, LLC
  • Washington
    • Bothell, Washington, United States, 98021
      • Arthritis Clinic: Western Washington Medical Group
    • Spokane, Washington, United States, 99204
      • Arthritis Northwest PLLC

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 14 years to 76 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Willing and able to give informed consent.
2. Willing and able to comply with the prescribed treatment protocol and evaluations for the duration of the trial.
3. Adult men or women ≥18 and <80 years of age.

4. Uncontrolled gout, defined as meeting the following criteria:

   • Hyperuricemia during the screening period defined as sUA ≥6 mg/dL, and;
   • Failure to maintain normalization of sUA with xanthine oxidase inhibitors at the maximum medically appropriate dose, or with a contraindication to xanthine oxidase inhibitor therapy based on medical record review or subject interview, and;

   • Symptoms of gout including at least 1 of the following:

     • Presence of at least one tophus
     • Recurrent flares defined as 2 or more flares in the past 12 months prior to screening
     • Presence of chronic gouty arthritis as evidenced by either clinical signs consistent with chronic synovitis on clinical examination or the presence of typical gouty erosion(s) on hand and/or foot X-rays
5. Willing to discontinue any oral urate lowering therapy for at least 7 days prior to MTX dosing at Week -4 and remain off while receiving pegloticase treatments.
6. Women of childbearing potential (including those with an onset of menopause <2 years prior to screening, non-therapy-induced amenorrhea for <12 months prior to screening, or not surgically sterile [absence of ovaries and/or uterus]) must have negative serum/urine pregnancy tests during Screening and Week -4; subjects must agree to use 2 reliable forms of contraception during the trial, one of which is recommended to be hormonal, such as an oral contraceptive. Hormonal contraception must be started ≥1 full cycle prior to Week -4 (start of MTX) and continue for 4 weeks/30 days after the last dose of pegloticase, or at least one ovulatory cycle after the last dose of MTX (whichever is the longest duration after the last dose of pegloticase or MTX). Highly effective contraceptive methods (with a failure rate <1% per year), when used consistently and correctly, include implants, injectables, combined oral contraceptives, some intrauterine devices, sexual abstinence, or vasectomized partner.
7. Men who are not vasectomized must agree to use appropriate contraception so as to not impregnate a female partner of reproductive potential during the trial, beginning with the initiation of MTX at Week -4 and continuing and for at least 3 months after the last dose of MTX.
8. Able to tolerate MTX 15 mg orally for 4 weeks (Week -4 through Day 1) prior to enrollment.

Exclusion Criteria:

1. Weight >160 kg (352 pounds) at Screening.
2. Any serious acute bacterial infection, unless treated and completely resolved with antibiotics at least 2 weeks prior to the Day 1 Visit.
3. Severe chronic or recurrent bacterial infections, such as recurrent pneumonia or chronic bronchiectasis.
4. Current or chronic treatment with systemic immunosuppressive agents such as MTX, azathioprine, or mycophenolate mofetil; prednisone ≥10 mg/day or equivalent dose of other corticosteroid on a chronic basis (3 months or longer) would also meet exclusion criteria.
5. History of any transplant surgery requiring maintenance immunosuppressive therapy.
6. Known history of hepatitis B virus surface antigen positivity or hepatitis B DNA positivity.
7. Known history of hepatitis C virus RNA positivity, unless treated and viral load is negative.
8. Known history of Human Immunodeficiency Virus (HIV) positivity.
9. Glucose-6-phosphate dehydrogenase deficiency (tested at the Screening Visit centrally or locally).
10. Chronic renal impairment defined as estimated glomerular filtration rate (eGFR) <40 mL/min/1.73 m^2 or currently on dialysis.
11. Non-compensated congestive heart failure or hospitalization for congestive heart failure within 3 months of the Screening Visit, uncontrolled arrhythmia, treatment for acute coronary syndrome (myocardial infarction or unstable angina), or uncontrolled blood pressure (>160/100 mmHg) prior to enrollment at Day 1.
12. Pregnant, planning to become pregnant, breastfeeding, planning to impregnate female partner, or not on an effective form of birth control, as determined by the Investigator.
13. Prior treatment with pegloticase, another recombinant uricase (rasburicase), or concomitant therapy with a polyethylene glycol-conjugated drug.
14. Known allergy to pegylated products or history of anaphylactic reaction to a recombinant protein or porcine product.
15. Contraindication to MTX treatment or MTX treatment considered inappropriate.
16. Known intolerance to MTX.
17. Receipt of an investigational drug within 4 weeks or 5 half-lives, whichever is longer, prior to MTX administration at Week -4 or plans to take an investigational drug during the trial.
18. Liver transaminase levels (AST or ALT) > 1.25 X upper limit of normal (ULN) or albumin < the lower limit of normal (LLN) at the Screening Visit.
19. Chronic liver disease.
20. White blood cell count <4000/µl, hematocrit <32 percent, or platelet count <75,000/µl.
21. Currently receiving systemic or radiologic treatment for ongoing cancer, excluding non-melanoma skin cancer.
22. History of malignancy within 5 years other than non-melanoma skin cancer or in situ carcinoma of cervix.
23. Diagnosis of osteomyelitis.
24. Known history of hypoxanthine-guanine phosphoribosyl-transferase deficiency, such as Lesch-Nyhan and Kelley-Seegmiller syndrome.
25. Unsuitable candidate for the trial, based on the opinion of the Investigator (e.g., cognitive impairment), such that participation might create undue risk to the subject or interfere with the subject's ability to comply with the protocol requirements or complete the trial.
26. Alcohol use in excess of 3 alcoholic beverages per week.
27. A known intolerance to all protocol standard gout flare prophylaxis regimens (i.e., subject must be able to tolerate at least one: colchicine and/or non-steroidal anti-inflammatory drugs and/or low dose prednisone ≤10 mg/day).
28. Current pulmonary fibrosis, bronchiectasis or interstitial pneumonitis. If deemed necessary by the Investigator, a chest X-ray may be performed during Screening.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Pegloticase 16mg cohort; 16 mg IV dose of pegloticase q4 weeks with 15 mg methotrexate (MTX) weekly	Biological: Pegloticase; IV dose of pegloticase q4 weeks co-administered with weekly oral methotrexate; Drug: Methotrexate (MTX); 15 mg oral dose methotrexate administered weekly
Experimental: Pegloticase 24/32mg cohort; 24 to 32 mg IV dose of pegloticase q4 weeks with 15 mg MTX weekly	Biological: Pegloticase; IV dose of pegloticase q4 weeks co-administered with weekly oral methotrexate; Drug: Methotrexate (MTX); 15 mg oral dose methotrexate administered weekly

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of Participants Who Were Serum Uric Acid (sUA) Responders (sUA < 6 mg/dL) During Month 6	Responders are defined as participants achieving and maintaining sUA < 6 mg/dL for at least 80% of the time during Month 6. Participants meeting the sUA discontinuation criteria (pre-infusion sUA >6 mg/dL at 2 consecutive scheduled trial visits beginning with the Week 1 Visit) were counted as non-responders.	Month 6 (Weeks 20, 21, 22, 23, and 24)
Time to First sUA ≥6 mg/dL After First Achieving sUA <6 mg/dL, From the First Pegloticase Infusion Until Week 24	The number of participants who had pre-Infusion sUA ≥ 6 mg/dL post-day 1 pegloticase infusion were included in this analysis. The date of the first pre-infusion sUA ≥ 6 mg/dL was the event date. Participants who did not have the event were censored at the date of the last collected pre-infusion sample with non-missing sUA result. Participants who never achieved sUA < 6 mg/dL were excluded from the analysis.	Day 1 to Week 24

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Maximum Concentration (Cmax) of Pegloticase	Noncompartmental Pharmacokinetic (PK) parameters of pegloticase were estimated using concentration data after the first dose (including Week 4 predose concentration data) using Phoenix WinNonlin® software. The linear/log trapezoidal rule was used in conjunction with the appropriate noncompartmental model, with input values for dose level, dosing time, serum concentration, and corresponding real-time values, based on drug dosing times whenever possible. Below limit of quantification (BLQ) values prior to the first quantifiable concentration were set to 0; BLQ values at all other time points were set to half the lower limit of quantification (LLOQ) (0.025 µg/mL).	Post infusion on Day 1, at Weeks 1, 2, 3 and pre-dose at Week 4
Area Under the Concentration- Time Curve From Time 0 to Week 4 Predose of Pegloticase	Noncompartmental PK parameters of pegloticase were estimated using concentration data after the first dose (including Week 4 predose concentration data) using Phoenix WinNonlin® software. The linear/log trapezoidal rule was used in conjunction with the appropriate noncompartmental model, with input values for dose level, dosing time, serum concentration, and corresponding real-time values, based on drug dosing times whenever possible. BLQ values prior to the first quantifiable concentration were set to 0; BLQ values at all other time points were set to half LLOQ (0.025 µg/mL).	Post infusion on Day 1, at Weeks 1, 2, 3 and pre-dose at Week 4
Trough Serum Concentration (Ctrough) of Pegloticase at Week 24 Pre-dose	Blood samples were collected for measurement of serum concentrations of pegloticase. The median concentration of pegloticase taken at Week 24 pre-dose was reported as the Ctrough concentration at Week 24.	Week 24 Pre-dose
Percentage of Participants With Pre-infusion sUA <6 mg/dL at Each Scheduled Visit	The percentage of participants with pre-infusion sUA <6 mg/dL at each scheduled infusion visit, regardless of treatment status, was presented.	Pre-infusion on Day 1, Weeks 4, 8, 12, 16, 20, 24, 28, 32, 36, 40 and 44
Area Under the sUA Concentration vs Time Curve From Day 1 to Week 24 and Day 1 to Week 48	The AUC from Day 1 to Week 24 and from Day 1 to Week 48 was calculated as time-adjusted AUC derived using the trapezoidal rule divided by the number of total days in the given period. The AUC from Day 1 to Week 48 was only calculated for participants who continued in the optional treatment period from Week 24 to Week 48.	Day 1 to Week 24 and Day 1 to Week 48
Percentage of Time Participants Sustained sUA < 6 mg/dL From Day 1 to Week 24 or Day 1 to Week 48	The percentage of time that participants sustained sUA < 6 mg/dL was derived using linear interpolation across all observed data points between Day 1 and the end of each analysis period. The percentage of time during a given period is the time that sUA < 6 mg/dL divided by the total time from the first to the last scheduled visit in the given period.	Day 1 to Week 24 and Day 1 to Week 48
Percentage of Participants With Anti-uricase Antibodies at Each Scheduled Visit	Pegloticase immunogenicity was assessed by incidence of anti-poly (Ethylene Glycol) (PEG) and anti-uricase immunoglobulin G (IgG) antibodies. The percentage of participants who were treatment-emergent anti-drug antibody (ADA) positive is presented below. Participants were considered treatment-emergent ADA positive if they were ADA negative at the data collection timepoint of Day 1 (Baseline) and ADA positive at one of the specified post-dose timepoints.	Day 1 (Baseline) and Weeks 2, 4, 8, 16, 24, 36 and 48
Percentage of Participants With Anti-PEG Antibodies at Each Scheduled Visit	Pegloticase immunogenicity was assessed by incidence of anti-PEG and anti-uricase IgG antibodies. The percentage of participants who were treatment-emergent ADA positive is presented below. Participants were considered treatment-emergent ADA positive if they were ADA negative at the data collection timepoint of Day 1 (Baseline) and ADA positive at one of the specified post-dose timepoints.	Day 1 (Baseline) and Weeks 2, 4, 8, 16, 24, 36 and 48

Collaborators and Investigators

• Sponsor: Amgen
• Investigators: Study Director: Supra Verma, MD, Horizon Therapeutics; Study Director: MD, Amgen

Publications and helpful links

Helpful Links

• AmgenTrials clinical trials website

Study record dates

Study Major Dates

• Study Start (Actual): January 26, 2021
• Primary Completion (Actual): May 18, 2023
• Study Completion (Actual): December 20, 2023

Study Registration Dates

• First Submitted: February 12, 2021
• First Submitted That Met QC Criteria: February 17, 2021
• First Posted (Actual): February 21, 2021

Study Record Updates

• Last Update Posted (Actual): May 19, 2026
• Last Update Submitted That Met QC Criteria: April 27, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Methotrexate; Gout; KRYSTEXXA; Pegloticase; Uncontrolled gout
• Additional Relevant MeSH Terms: Crystal Arthropathies; Musculoskeletal Diseases; Arthritis; Joint Diseases; Rheumatic Diseases; Purine-Pyrimidine Metabolism, Inborn Errors; Metabolism, Inborn Errors; Genetic Diseases, Inborn; Metabolic Diseases; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Nutritional and Metabolic Diseases; Gout; Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Pterins; Pteridines; Aminopterin; Methotrexate; Pegloticase
• Other Study ID Numbers: HZNP-KRY-408

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No