An Observational Extension Study for Adult Patients Treated in Study R5459-RT-1944 Who Receive a Kidney Transplant

A Noninterventional Extension Study for Patients Treated in Study R5459-RT-1944 With Vonsetamig (BCMA x CD3 Bispecific Antibody) Who Receive a Kidney Transplant

The main purpose of this study is to continue to see how vonsetamig works in the body and to monitor the outcomes after kidney transplant for participants previously treated in the R5459-RT-1944 study (NCT05092347).

No study drug will be given during this study.

Study Overview

• Status: Recruiting
• Conditions: Chronic Kidney Disease (CKD)
• Intervention / Treatment: Drug: Noninterventional

• Study Type: Observational
• Enrollment (Estimated): 20

Contacts and Locations

• Study Contact: Name: Clinical Trials Administrator; Phone Number: 844-734-6643; Email: clinicaltrials@regeneron.com

Study Locations

• United States
  • California
    • Los Angeles, California, United States, 90048
      • Recruiting
      • Cedars-Sinai Medical Center
    • Orange, California, United States, 92868
      • Recruiting
      • University of California Irvine
    • San Francisco, California, United States, 94143
      • Recruiting
      • Connie Frank Transplant Center at UCSF
  • Connecticut
    • New Haven, Connecticut, United States, 06520
      • Recruiting
      • Yale University of Medicine
  • Illinois
    • Chicago, Illinois, United States, 60611
      • Recruiting
      • Comprehensive Transplant Center
  • Maryland
    • Baltimore, Maryland, United States, 21224
      • Recruiting
      • John Hopkins Hospital
  • Minnesota
    • Minneapolis, Minnesota, United States, 55455
      • Recruiting
      • University of Minnesota
  • New York
    • New York, New York, United States, 10016
      • Recruiting
      • New York University Langone Health
  • Pennsylvania
    • Philadelphia, Pennsylvania, United States, 19104
      • Recruiting
      • Penn Transplant Institute

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

This study is designed to collect safety and outcomes data in patients aged 18 through 70 years who receive a kidney transplant and were administered vosentamig in study R5459-RT-1944 [NCT05092347].

Description

Inclusion Criteria:

1. Received at least 1 dose of treatment with vonsetamig in study R5459-RT-1944 [NCT05092347].
2. Received after acceptable crossmatching, a kidney transplant while enrolled in study R5459-RT-1944
3. Willing and able to comply with clinic visits and study-related procedures
4. Provide informed consent signed by study patient or legally acceptable representative

Exclusion Criteria:

1.There are no exclusion criteria for this study.

Note: Other protocol defined Inclusion/Exclusion criteria may apply

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Vonsetamig in study R5459-RT-1944; Received a kidney transplant and were administered vonsetamig in study R5459-RT-1944 [NCT05092347].	Drug: Noninterventional; No investigational treatment will be given in this noninterventional extension study; Other Names: REGN5459

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Incidence of Adverse Events	Up to 12 months post-kidney transplant
Incidence of Serious Adverse Events	Up to 12 months post-kidney transplant

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of biopsy-proven kidney allograft rejection	Responsiveness to therapy by 12 months of each of the following types of biopsy-proven kidney allograft rejection according to Banff classification: Active antibody-mediated rejection (AMR) (Category 2); Chronic active AMR (Category 2); Acute t-cell-mediated rejection (TCMR) (Category 4); Chronic active TCMR (Category 4)	Up to 12 Months
Time to diagnosis of biopsy-proven kidney allograft rejection	Responsiveness to therapy by 12 months of each of the following types of biopsy-proven kidney allograft rejection according to Banff classification: Active antibody-mediated rejection (AMR) (Category 2); Chronic active AMR (Category 2); Acute t-cell-mediated rejection (TCMR) (Category 4); Chronic active TCMR (Category 4)	Up to 12 Months
Responsiveness to therapy by 12 months of biopsy-proven kidney allograft rejection	Responsiveness to therapy by 12 months of each of the following types of biopsy-proven kidney allograft rejection according to Banff classification: Active antibody-mediated rejection (AMR) (Category 2); Chronic active AMR (Category 2); Acute t-cell-mediated rejection (TCMR) (Category 4); Chronic active TCMR (Category 4)	Up to 12 Months
Incidence of graft loss	Incidence of graft loss (defined as becoming dialysis-dependent) by 12 months	Up to 12 Months
Time to graft loss	Time to graft loss (defined as becoming dialysis-dependent) by 12 months	Up to 12 Months
Change in estimated glomerular filtration rate (eGFR) over time		Up to 12 Months
Incidence of delayed graft function	Incidence of delayed graft function (defined as the use of dialysis within 7 days posttransplant)	Up to Day 7
Percent Change in anti-HLA alloantibodies	Percent Change in anti-HLA alloantibodies (SAB assay) compared with pretransplant levels at 2, 3, 6, and 12 months, and at the time of suspected clinical episodes of allograft rejection	Up to 12 months
Mean Fluorescence Intensity Change in anti-HLA alloantibodies	Mean Fluorescence Intensity (MFI) Change in anti-HLA alloantibodies (SAB assay) compared with pretransplant levels at 2, 3, 6, and 12 months, and at the time of suspected clinical episodes of allograft rejection	Up to 12 months
Change in Calculated panel-reactive antibody (cPRA) over time		Up to 12 Months
Percent Change in donor-specific anti-HLA alloantibodies	Percent Change in donor-specific anti-HLA alloantibodies compared with recipient pre-transplant anti-HLA alloantibody levels	Up to 12 Months
Mean Fluorescence Intensity Change in donor-specific anti-HLA alloantibodies	Mean Fluorescence Intensity Change in donor-specific anti-HLA alloantibodies compared with recipient pre-transplant anti-HLA alloantibody levels	Up to 12 Months
Incidence of de novo anti-HLA alloantibody development	Cumulative incidence of de novo anti-HLA alloantibody development by SAB assay by 12 months	Up to 12 Months
Serum Concentrations of Ig classes (IgG, IgA, and IgM) over time		Up to 12 Months
Percent change from baseline of circulating serum concentrations of Ig classes	Percent change from baseline of circulating serum concentrations of Ig classes (IgG, IgA, and IgM)	Up to 12 Months
Serum Concentration of vonsetamig		Up to 12 Months

Collaborators and Investigators

• Sponsor: Regeneron Pharmaceuticals
• Investigators: Study Director: Clinical Trial Management, Regeneron Pharmaceuticals

Study record dates

Study Major Dates

• Study Start (Actual): October 19, 2023
• Primary Completion (Estimated): June 15, 2026
• Study Completion (Estimated): February 23, 2028

Study Registration Dates

• First Submitted: October 22, 2021
• First Submitted That Met QC Criteria: October 22, 2021
• First Posted (Actual): November 3, 2021

Study Record Updates

• Last Update Posted (Actual): April 17, 2026
• Last Update Submitted That Met QC Criteria: April 14, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Kidney Transplant
• Additional Relevant MeSH Terms: Urogenital Diseases; Pathologic Processes; Male Urogenital Diseases; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Chronic Disease; Disease Attributes; Renal Insufficiency; Pathological Conditions, Signs and Symptoms; Renal Insufficiency, Chronic
• Other Study ID Numbers: R5459-RT-1956

Drug and device information, study documents

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