Kidney Week

Abstract: SA-OR052

Preliminary Data from PrisMN, a Phase 2 Study Evaluating the Safety and Efficacy of Budoprutug, an Investigational Low-Fucosylated Anti-CD19 Monoclonal Antibody (mAb), in Patients with Primary Membranous Nephropathy (PMN)

Session Information

• Glomerular Diseases: Clinical Trial Results
  October 24, 2026 | Location: Mile High Ballroom 4A, Convention Center
  Abstract Time: 05:30 PM - 05:40 PM

Category: Glomerular Diseases

• 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics

Authors

• Cortazar, Frank B., New York Nephrology Vasculitis and Glomerular Center, Albany, New York, United States

Frank B. Cortazar, MD

• Dudar, Iryna, Kyiv City Medical Center, Kyiv, Ukraine

Iryna Dudar, MD, PhD

• Kooienga, Laura, Colorado Kidney Care, Denver, Colorado, United States

Laura Kooienga, MD

• Smuclir Quevedo, Maria Alejandra, Investigación Clinica Aplicada SRL, Buenos Aires, Argentina

Maria Alejandra Smuclir Quevedo, MD

• Korman Turk, Laurencia, DOM Centro de Reumatologia, Buenos Aires, Argentina

Laurencia Korman Turk, MD

• Tchokhonelidze, Irma, Tbilisi State Medical University and Ingorokva High Medical Technology University Clinic, Tbilisi, Georgia

Irma Tchokhonelidze, MD, PhD

• Tataradze, Avtandil, Israeli-Georgian Medical Research Clinic Healthycore, Tbilisi, Georgia

Avtandil Tataradze, MD

• Luo, Stacey, Climb Bio, Inc., Wellesley, Massachusetts, United States

Stacey Luo, PharmD, RPh

• Charles, Edgar D., Climb Bio, Inc., Wellesley, Massachusetts, United States

Edgar D. Charles, MD

Group or Team Name

• PrisMN Trial Investigators

Background

PMN is a rare, autoantibody-mediated disease that can cause progressive renal dysfunction and remains in need of effective therapies. Budoprutug (TNT119) is an investigational CD19 mAb with picomolar affinity for CD19 and enhanced ADCC. Since CD19 is expressed from early B-cell development through plasmablasts and plasma cell subsets, budoprutug may durably deplete pathogenic autoantibody-producing B cells. In a Phase 1b study (Cortazar ASN 2024), budoprutug was well tolerated. All 5 participants (pts) who received all 4 budoprutug doses responded: 3 with durable CR, 2 with PR, by Wk 48.

Methods

PrisMN, a Phase 2 study (NCT07096843) is enrolling 45 pts across 3 dose cohorts (200, 600, 1000 mg). Budoprutug is administered IV at Wks 0, 2, 24, and 26. Key inclusion criteria are positive PLA2R Abs, CD19+ B-cells ≥40 cells/μL, spot UPCR ≥2.0 g/g, eGFR ≥40 mL/min/1.73m², stable RAASi therapy. The 1^o objective is safety; 2^o objectives include PD, efficacy.

Results

11 pts were enrolled as of 5/1/2026 (200 mg), mean age 50 (31-62), mean 33 months from diagnosis (3-168). Pts had moderate/severe PMN: mean UPCR 6.93 g/g (2.85-13.37), PLA2R Ab 339 RU/mL (21.8-1335.6); EGFR 67 mL/min/1.73m² (42-119). B-cell depletion was rapid and durable with all 5 pts achieving >90% reduction after initial two doses of budoprutug (Figure). 13 AEs were observed in 6 pts; 10/13 were mild. 1 pt had an SAE: asymptomatic neutropenia (ANC <0.40) with onset at Day 57 and which resolved after G-CSF.

Conclusion

Preliminary data from the lowest dose PrisMN cohort are consistent with Phase 1b results, showing >90% B-cell depletion in moderate/severe PMN. Updated data across all endpoints, including safety, UPCR, PLA2R Abs, and B-cell counts will be presented at the conference.

Figure: Absolute CD20+ B-cell count in 5 pts who received 2/4 doses of budoprutug, measured from the first administered dose of budoprutug

Funding

• Commercial Support – Climb Bio, Inc.