Climb Bio (NASDAQ:CLYM) outlined its strategy and upcoming clinical milestones during a fireside chat at Oppenheimer’s 36th Annual Healthcare Life Sciences Conference, with Chief Medical Officer Edgar Charles and CFO Susan Altschuller joining analyst Leland Gershell.
Management said the company is building a pipeline of monoclonal antibodies for immune-mediated diseases driven by B cells and pathogenic autoantibodies, focusing on “clinically validated targets” including CD19 and APRIL. The executives emphasized what they view as advantages of an antibody approach compared with cell therapies, including a potentially safer and more community-friendly dosing paradigm.
Strategy: targeting validated biology with monoclonal antibodies
Discussing the company’s two lead programs—budoprutug (anti-CD19) and CLYM116 (anti-APRIL)—management described both as externally sourced assets that it believes were either overlooked or could be meaningfully differentiated. On CD19, the team cited what it sees as “white space” for antibody-based CD19 depletion beyond currently marketed options, while on APRIL it argued that an “APRIL-only” strategy could avoid potential added immunosuppressive liability from BAFF inhibition.
Budoprutug in primary membranous nephropathy: rationale and early clinical signal
Climb’s lead indication for budoprutug is primary membranous nephropathy (PMN), which Charles described as the leading cause of nephrotic proteinuria worldwide in non-diabetic adults, noting there are no approved agents and that treatment today relies on off-label use of therapies such as calcineurin inhibitors, cyclophosphamide, and rituximab.
Charles said CD19 is expressed early in the B-cell lineage through plasmablasts and on a subset of plasma cells, and he emphasized that later-stage cells are responsible for producing pathogenic autoantibodies. In PMN, he highlighted the link between anti-PLA2R antibodies and disease biology, and said depleting the cells that produce these antibodies—and cells that give rise to them—could drive deep and durable responses.
Climb discussed phase 1b data in PMN that it characterized as compelling. In five evaluable patients who received the full dose regimen, Charles said the company observed profound peripheral B-cell depletion, reductions in PLA2R antibodies in patients with detectable baseline antibodies, and proteinuria improvements. He added that all five evaluable patients had a proteinuria response (partial or complete remission), with 60% (three out of five) achieving complete remission, and that remissions were stable for up to three years off treatment.
The company said it is currently enrolling a phase 2 study in nephrotic PMN patients evaluating three ascending IV dose regimens. Endpoints include peripheral B-cell depletion, immunologic response (PLA2R antibody reduction), and proteinuria response measured by UPCR. Management said it expects initial results by the end of this year, including B-cell depletion, immunologic response, and “directional” improvements in proteinuria.
Subcutaneous formulation: optionality and upcoming healthy-volunteer data
Climb is also developing a subcutaneous (sub-Q) formulation of budoprutug. Charles said formulation work has enabled high concentration with low viscosity, which he said should support sub-Q administration at tolerable volumes. He framed sub-Q as providing optionality for patients and clinicians, particularly in diseases requiring repeat chronic administration, while noting that budoprutug’s dosing burden may be limited.
Altschuller added that, given the current IV dosing regimen under study (described as four doses and then dosing six months apart), a sub-Q version may not be necessary for every indication, but could be used where it best matches disease needs. The company expects phase 1 healthy volunteer sub-Q data in the first half of the year.
Additional budoprutug studies: ITP and SLE readouts expected in 2H
Climb is also enrolling a study in immune thrombocytopenic purpura (ITP). Charles described ITP as a classic autoantibody-driven disease where existing therapies may be limited by relapse after discontinuation or lack of durable complete remission. He said budoprutug could reduce pathogenic autoantibodies by targeting B cells that give rise to antibody-producing plasmablasts and plasma cells, potentially enabling a more durable “B-cell reset.”
In ITP, Charles noted that platelet counts provide an objective and relatively rapid efficacy readout. The ITP study includes ascending dose cohorts and a dose-expansion phase after dose selection, with assessments of B-cell depletion, platelet responses, and durability of remission.
Management also referenced systemic lupus erythematosus (SLE) as an area of interest; Altschuller described SLE work as “more of a translational experiment right now,” and said it could warrant partnership depending on results. The company expects initial data from budoprutug in ITP and SLE in the second half of the year, alongside PMN data.
CLYM116: “sweeper” anti-APRIL antibody positioned for IgA nephropathy
Turning to CLYM116, the company discussed the evolving IgA nephropathy (IgAN) treatment landscape, including updated KDIGO guidance emphasizing a two-pronged approach: agents aimed at slowing nephron loss (such as RAS inhibition and endothelin receptor antagonists, alongside lifestyle and blood pressure control) and targeted therapies addressing upstream drivers.
Charles called APRIL a “clear driver” of IgAN biology and said he expects APRIL targeting to become a mainstay in treatment. He cited encouraging phase 2 results from sibeprenlimab in reducing APRIL and IgA and improving UPCR and eGFR, while noting that the field is awaiting phase 3 eGFR results.
Climb said it believes it can improve on existing approaches with CLYM116, which it described as a novel “sweeper” antibody. Charles said the antibody uses a pH-dependent bind-and-release mechanism intended to capture APRIL in the periphery and target it for destruction in endosomes, which the company believes could provide potency and pharmacokinetic advantages. He said Climb aims to reduce APRIL to very low levels across the dosing interval, with the goal of deeper IgA reductions and improved dosing convenience compared with every-four-week regimens.
In non-human primate head-to-head studies versus sibeprenlimab, management said CLYM116 showed improved and more durable IgA reduction (maintained out to at least 60 to 90 days post-dose) and a half-life two to three times longer, which it said supports exploring dosing every eight or potentially every 12 weeks in IgAN patients.
For early clinical evaluation, the company said key near-term markers will include IgA as an immediate pharmacodynamic readout and “full APRIL suppression over the dosing interval,” with UPCR and eGFR slope stabilization expected to be central to registrational studies.
Climb expects healthy volunteer data for CLYM116 in the middle of the year.
Cash runway and 2025 milestone cadence
Altschuller said Climb’s cash runway extends into 2028, which she described as more than 12 months beyond the company’s planned readouts this year. She added that the company may seek to raise additional capital depending on opportunities, including potential pivotal trials and expansion into additional indications. She also said that a PMN pivotal trial of roughly 150 patients would be within the company’s ability to execute as a small biotech.
Management summarized five clinical data readouts expected this year:
- First half: Phase 1 healthy volunteer sub-Q data for budoprutug
- Mid-year: Healthy volunteer data for CLYM116 (IgAN program)
- Second half: Initial budoprutug data in ITP
- Second half: Initial budoprutug data in SLE
- Second half: Initial budoprutug data in PMN (phase 2)
On long-term follow-up from the earlier PMN experience, management said the prior study had been ended and that additional extended follow-up beyond the three-year observations discussed would not be available.
About Climb Bio (NASDAQ:CLYM)
Climb Bio Therapeutics, Inc is a clinical-stage biotechnology company focused on the discovery and development of engineered protein therapeutics for the treatment of cancer and immune-mediated disorders. The company’s mission centers on designing biologics with enhanced specificity and functional activity to engage key cellular targets and improve patient outcomes in areas of high unmet need.
At the heart of Climb Bio’s approach is its proprietary protein engineering platform, which combines mammalian cell display, directed evolution and computational modeling.
