Climb Bio (NASDAQ:CLYM) outlined a slate of near-term clinical milestones and its broader autoimmune disease strategy during a fireside chat at the Guggenheim Emerging Outlook Biotech Summit 2026, with Chief Financial Officer Susan Altschuller and Chief Business Officer Perrin Wilson highlighting five clinical data readouts expected this year across two antibody programs.
Multiple clinical readouts planned across two programs
Altschuller said the company is focused on autoimmune diseases and currently has two antibodies in the clinic. For its CD19-targeting monoclonal antibody, she said Climb expects data from a healthy volunteer study of a subcutaneous (subQ) formulation in the first half of the year. In the second half, the company expects initial data from a Phase 1b study in immune thrombocytopenia (ITP), a Phase 1b study in systemic lupus erythematosus (SLE), and initial data from a Phase 2 study in primary membranous nephropathy (PMN).
CD19 program: positioning, formulation strategy, and PMN focus
In discussing the CD19 landscape, the executives noted that UPLIZNA is the only approved CD19 antibody on the market and characterized it as a depleting antibody with success in rare neuro indications. Climb said it has not performed a head-to-head comparison, but Wilson and Altschuller said they believe their antibody has greater affinity to CD19 and that Climb may be able to offer a subQ formulation option that UPLIZNA does not.
They also emphasized that Climb believes a depleting mechanism is “critically important” in the autoimmune diseases it is pursuing.
On formulation strategy, Altschuller said the company is still working through whether it will pursue both intravenous (IV) and subQ options, describing subQ as a potential differentiator that could provide “optionality.” She pointed to earlier PMN data in which budoprutug was dosed every six months and said for some indications that dosing paradigm “is going to be sufficient,” while in others Climb could consider bridging from IV to subQ depending on the subQ data and dosing characterization.
PMN: unmet need, early signals, and Phase 2 design
Wilson described PMN as an area with “no approved therapies,” where calcineurin inhibitors, ACE inhibition, and off-label rituximab are commonly used. She said there is a “huge unmet need,” citing that rituximab leads to complete renal remission in about 10% of patients after one year and about 35% after two years. Wilson identified complete renal remission—defined as proteinuria less than 0.3 grams per gram—as the approvable endpoint.
Climb discussed an earlier Phase 1b study in PMN that enrolled eight patients, with five evaluable patients receiving four full doses of budoprutug. Wilson said the company observed a 60% complete remission rate in those evaluable patients and reported that 100% of patients who entered the study as PLA2R antibody-positive achieved a serological remission.
The company’s ongoing Phase 2 PMN study began in November and is described as a roughly 45-patient trial evaluating three doses. While Climb did not disclose the specific doses, Wilson said the lowest dose in Phase 2 is “effectively quite equivalent” to what was studied in Phase 1b, with higher doses stepping up from there. She added that budoprutug was originally studied in oncology up to 1,000 mg, which the company views as supporting a “very large therapeutic window.”
Wilson said the regimen is delivered in six-month cycles, with dosing on day 0 and day 14, followed by a second cycle at six months—similar to approaches used with rituximab and UPLIZNA. She also reiterated that among four Phase 1b PMN patients followed long term, three did not require additional immunologic intervention after the first year of therapy.
On what would constitute success in Phase 2, Wilson said replicating Phase 1b outcomes would be compelling. She said Climb expects to select dose based on B-cell depletion and PLA2R, which she described as predictive in PMN.
In terms of market opportunity, Wilson estimated about 70,000 PMN patients in the U.S., with about two-thirds categorized as moderate-to-severe and likely to require therapeutic intervention. She said the anticipated path to approval is one Phase 3 study of about 150 patients with complete renal remission as the primary endpoint, referencing obinutuzumab’s “Majesty” study as a prominent precedent and noting a 104-week endpoint framework.
ITP and SLE: rationale and development intent
For ITP, Wilson described the indication as biomarker-driven and useful for establishing proof of concept and dosing in a non-renal disease. She said datasets show CD19-positive B cells can persist even after rituximab, and that in more refractory patients only about 20% achieve a durable platelet response. Climb, she said, recognizes “the bar is high” and that it would need to outperform that durability benchmark, but views ITP as potentially pivotable relatively quickly with the right dose.
For SLE, Wilson characterized the program as more translational, noting the need to start at subtherapeutic doses due to requirements for studies in the space and pointing to the heterogeneity and scale of pivotal trials (which she described as involving two trials and up to 1,000 patients). She said Climb is exploring whether it can achieve a “true immune reset” in SLE. The company also said it cleared an IND for a parallel SLE study in China aiming to enroll lupus nephritis patients and obtain tissue-level depletion data via biopsy.
APRIL-only “sweeper” antibody: mechanism and IgAN development approach
Climb’s second clinical program is an APRIL-only antibody (CLYM116) acquired from Mabworks that the executives said combines half-life extension with a “sweeper” mechanism—described as pH-dependent binding. Wilson explained that the antibody binds APRIL with high affinity at neutral pH, releases APRIL at low endosomal pH after internalization, enabling APRIL degradation, while the antibody is recycled via high FcRn binding to bind additional APRIL.
Wilson said Climb conducted a head-to-head non-human primate study comparing CLYM116 to sibeprenlimab, reporting two- to threefold longer half-life and greater IgA suppression: up to 70% or greater suppression from baseline for CLYM116 versus 50% for sibeprenlimab in the same experiment.
The company is running a Phase 1 healthy volunteer study with single ascending dose (and one multiple-interval dose cohort) to assess PK/PD, with data expected mid-year. Wilson said CLYM116 is being studied subQ, and Altschuller confirmed the animal studies were also subQ. When asked about dosing frequency, Wilson said the current study is intended to answer that question, adding that the company is “hoping” for at least every eight weeks and potentially every 12 weeks.
On pathway strategy, Wilson said Mabworks is also conducting a parallel healthy volunteer study in China that will proceed into an IgAN patient cohort. Climb said the combination of the China effort and its own study in Australia could enable a faster move into pivotal development in IgAN.
In explaining the choice of APRIL-only versus BAFF/APRIL approaches, Wilson said Climb’s decision was initially driven by the differentiation of the antibody and the promise for APRIL, and that subsequent Phase 3 readouts supported its view that APRIL-only is sufficient in IgAN. She added that BAFF inhibition could present long-term immunosuppression risk and referenced increased infection rates over time. Wilson also pointed to immunogenicity reported with sibeprenlimab and said Climb does not expect the same issue with CLYM116 based on binding epitope and complex formation observed in its experiments.
Cash runway
Altschuller said Climb last disclosed $176 million in cash at the end of the third quarter and recently updated guidance indicating cash runway into 2028—more than 12 months beyond the clinical readouts the company outlined for this year.
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.
