Climb Bio : Budoprutug and the CD19 Opportunity

Published: 2026-05-05 08:17:15 ET CLYM

Published on 05/05/2026 at 08:17 am EDT

MAY 5, 2026

Webcast Agenda

Corporate Strategy & Budoprutug Opportunity

Aoife Brennan, M.B., Ch.B.

President and CEO, Climb Bio

CD19: A Key Driver of B-Cell Mediated Autoimmune Disease

David Jayne, M.D.

Professor of Clinical Autoimmunity at the University of Cambridge

Director of the Vasculitis and Lupus Service at Addenbrooke's Hospital

Budoprutug: A Differentiated CD19 mAb with Broad Autoimmune Potential

Edgar Charles, M.D.

Chief Medical Officer, Climb Bio

Q&A session

including Dr. Jayne and management

Delivering Clinical Results and Advancing Development

Corporate Highlights

Developing differentiated, monoclonal antibody (mAb) therapeutics for immune-mediated diseases,

including those affecting kidney health, with expansive commercial opportunities

Leveraging clinically validated B cell targets, proven mAb modality, and indications with

well-defined endpoints and established regulatory pathways

Anticipating a data-rich 2026 with multiple clinical readouts across both clinical-stage programs

Budoprutug - anti-CD19 mAb in development for pMN, ITP, and SLE; Fast Track and Orphan Drug Designations granted for pMN

CLYM116 - anti-APRIL mAb in development for IgAN

Well-resourced to advance clinical programs through meaningful value-driving milestones,

with runway anticipated into 2028*

* Does not include the impact of proceeds from the April PIPE financing

pMN = primary membranous nephropathy, ITP = immune thrombocytopenia, SLE = systemic lupus erythematosus, IgAN = IgA nephropathy

Pipeline of Highly Differentiated mAbs

Anticipating initial readouts from all ongoing trials in 2026

PRE- CLINICAL

IND- ENABLING

PHASE 1

PHASE 2

PHASE 3

data mid-year '26

STATUS & ANTICIPATED MILESTONES

INDICATION(S)

Primary Membranous

Initial Ph2 data Q4 '26

Nephropathy

Budoprutug IV

Immune

Initial Ph1b data June '26

Anti-CD19

Thrombocytopenia

Additional Ph1b data YE '26

Systemic Lupus

FPI China Ph1b Q2 '26

Erythematosus

Initial Global Ph1b data Q4 '26

Budoprutug SC

Anti-CD19

Autoimmune

Disease

Initiate multiple dose patient study

CLYM116*

Anti-APRIL

IgA Nephropathy

Modeling/Ph1 HV safety June '26

Initial PK/PD Ph1 HV

Budoprutug SC and CLYM116 Phase 1 trials conducted in healthy volunteers (HV).

*Climb Bio has worldwide rights outside Greater China (defined as mainland China, Hong Kong, Macau, and Taiwan); Partner: Beijing Mabworks Biotech Co., Ltd.

CD19 mAb Targeting Remains a White Space

Low competitive intensity for an established modality translates into opportunity for budoprutug

CD19 Autoimmune Competitive Landscape1

B-Cell Depleting Approaches

Rationale for a mAb Approach

>13

>18

Monoclonal

Antibodies

T Cell

Engagers

Cell

Therapies

Targeted immunomodulation without lymphodepletion

Budoprutug Opportunity

Limited competition in CD19 mAb space relative to TCEs and cell therapies | Administration profile intended to support outpatient and community use | Potential to address multiple B-cell mediated autoimmune diseases

mAb = monoclonal antibody; TCEs = T cell engagers

Opportunity for a CD19 B-Cell Depleting mAb is Significant

Inebilizumab's commercial success in rare neurological diseases supports the viability of a CD19 mAb approach

Inebilizumab Consensus Sales Estimates1

Significant potential opportunity for budoprutug in B-cell mediated diseases beyond inebilizumab's neuro focus

$2,303

$2,122

$1,801

$1,458

$1,046

$655

$379

$244

$61 $155

$2,500

Global Net Revenue ($USD)

$2,000

$1,500

$1,000

$500

2021 2022 2023 2024 2025 2026E 2027E 2028E 2029E 2030E

NMOSD approval, Jun 2020; IgG4-RD approval, Apr 2025; gMG approval, Dec 2025

gMG = generalized myasthenia gravis, IgG4-RD = immunoglobulin G4-related disease, mAb = monoclonal antibody, NMOSD = neuromyelitis optica spectrum disorder

Budoprutug Target Indications Represent a Robust Opportunity Set

Pursuing development in diseases with large addressable populations and significant unmet need

EPIDEMIOLOGY (US)

UNMET NEED

BUDOPRUTUG OPPORTUNITY

Primary Membranous Nephropathy (pMN)

~75,000

patients1,2

Progressive renal disease characterized by proteinuria, nephrotic syndrome and progressive loss of renal function5

No approved therapies

Potential for long-term disease remission based on initial clinical data

Fast Track Designation granted

Immune Thrombocytopenia (ITP)

~85,000

patients2,3

Systemic Lupus Erythematosus (SLE)

~240,000

patients2,4

Chronic bleeding disorder characterized by

the destruction of platelets6

Poor QoL, with majority of previously treated patients failing to achieve durable platelet response6

Chronic autoimmune condition with severe disease manifestations that can affect virtually any organ system7

Majority of patients fail to achieve disease

control with existing treatments7

Potential to achieve durable response and disease remission in the previously treated population

Potential for broad B-cell targeting and disease suppression with the safety and convenience of a mAb

mAb = monoclonal antibody, QoL = quality of life

1 McGrogan Nephrol Dial Transplant 2011, 2 U.S. Census Estimates 2020-2025, 3 Feudjo-Tepie 2008, 4 Izmirly Arthritis Rheumatol 2021, 5 Ronco JCM 2021, 6 Gafter-Gvili Eur J Int Med 2023,

David Jayne, M.D.

University of Cambridge, UK

Disclosures: Consultancy or lecture fees from Abbvie, Alentis, Amgen, Astra-Zeneca, Climb Bio, CSL Vifor, Fate, GSK, Novartis and Otsuka, and grants from CSL Vifor, GSK, Roche/Genentech and UCB

Develop into plasmablasts and plasma cells that generate pathogenic antibodies

(e.g. pMN, ITP, SLE)

Support T cell autoreactivity (e.g. RA, MS)

Typically targeted by anti-CD20 monoclonal antibodies

(e.g. rituximab, ocrelizumab)

Kidney biopsy of a patient with pMN

IgG

Failure to remove circulating autoantibodies

Incomplete removal of tissue resident B cells

Only partial efficacy

and high relapse rate

SLE: anti-DNA antibodies after rituximab SLE: B cells in the kidney drive poor prognosis

CD19 promotes the growth, activation, proliferation, and signaling of B lymphocytes

CD19+ cells play an important role in the pathogenesis of autoimmune disorders

CD19 has a broad distribution within B cell and plasma cell development

Unlike CD20, CD19 is expressed on pro-B cells, plasmablasts and many plasma cells

"Double-Negative" (DN) B Cells

precursors of autoantibody-secreting cells

expanded in autoimmune diseases

like SLE

Defined by:

CD19+ IgD- CD27-CXCR5- CD24lo

Autoantibody-secreting surface Ig+ CD20− CD19+ CD38+

plasma cells in rituximab-refractory autoimmune patients

Clinical remission of rituximab-refractory autoimmune disease induced by anti-CD19 chimeric antigen receptor T cells

CD19+ plasma cells are not short-lived plasmablasts

Autoantigen-binding B cells and CD19+ plasma cells serve a critical role in perpetuating T cell activation in autoimmune disease

Before CAR T

Combined CD19 CD20 CD138

After CAR T

B cell compartment

Lymph node B cells after:

Obinutuzumab

CD19+

Post-OBI

Rituximab

Post-RTX

anti-CD19 CAR-T

Post-CAR

Durable remissions are associated with a B cell reset and deep depletion of B cells and plasma cells

Targeting CD19 rather than CD20 offers potential for more complete B cell depletion, which can potentially be achieved with a monoclonal antibody approach

This is likely to be particularly important in removing pathogenic autoantibodies, which is relevant for the treatment of many autoimmune diseases

CD19 is Emerging as a Preferred Pan-B-Cell Target

Broad B-cell expression profile with potential for achieving deeper and more durable B-cell depletion

CD19 plays a mechanistic role across all stages of B-cell development, providing potential for profound and durable depletion of B cells and pathogenic autoantibodies1

Naked mAbs targeting CD20 have been shown to deplete B cells in tissue2

Deeper depletion may be achieved by targeting CD19

Bone marrow

Blood, lymphoid organs, tissues

Bone marrow

Naive

B cell

Memory

B cell

CD19-

plasma cell

CD19+

plasma cell

CD19+

plasma cell

Short-lived

plasmablast

Immature

B cell

Pre-pro

B cell

CLP

Legend

CD19

CD38

CD20

CD19 depletion

CD38 depletion

CD20 depletion

CLP = common lymphoid progenitor, GC = germinal center, mAbs = monoclonal antibodies

1 Adapted from Suan J Immunol 2025, 2 Tur Annals Rheum Dis 2024

Disclaimer

Climb Bio Inc. published this content on May 05, 2026, and is solely responsible for the information contained herein. Distributed via Public Technologies (PUBT), unedited and unaltered, on May 05, 2026 at 12:16 UTC.