Data Readout

Climb Bio's budoprutug already showed 90% B-cell depletion in ITP before H2 data

The Phase 1b/2a trial's initial cohort posted platelet gains at EHA in June, so the H2 2026 readout Climb Bio flagged will extend, not introduce, an efficacy signal.

By AppliedXLJuly 13, 2026Trial NCT07043946

Executive Summary

Climb Bio's anti-CD19 antibody has already shown a B-cell depletion and platelet response signal in an early cohort of its ITP trial, ahead of the broader H2 2026 data the company has flagged.
No other industry program combines this target and mechanism in this indication, so the interim signal stands without a resolved peer outcome to check it against.
The trial is moving into a higher-dose cohort, and the next disclosure will show whether the platelet effect holds as dosing intensifies and follow-up lengthens.
The study remains small and early-phase, so any single readout will be hypothesis-generating for dose selection rather than a decision on efficacy.

What already posted

At the European Hematology Association meeting on June 11-14, 2026, Climb Bio presented initial Phase 1b results from 15 patients enrolled in NCT07043946, its open-label, dose-escalation Phase 1b/2a trial of budoprutug in ITP. In the 250 mg cohort, B-cell depletion exceeded 90% by week four and mean platelet count rose by 111,000/microliter at week 24, with durable platelet responses in four of six patients, and no serious adverse events or discontinuations reported across the interim set. That data followed guidance the company issued across three consecutive disclosures, in November 2025, January 2026, and March 2026, all pointing to initial ITP data including preliminary efficacy in the second half of 2026. NCT07043946+1

Probability of Success

Endpoint Met16%

Completes52%

Clinical Significance19%

Regulatory11%

What the trial still tests

The registered primary endpoint is the incidence of treatment-emergent adverse events, with ten secondary measures spanning B-cell depletion, platelet response, pharmacokinetics, and anti-drug antibodies. The trial targets 24 adult patients with prior treatment failure, dosed intravenously, and is enrolling across Ukraine, Greece, Spain, Bulgaria, and Serbia toward a primary completion date of August 2027. The company has said enrollment is ongoing in the 1000 mg cohort, with additional data anticipated by year-end 2026, positioning the next disclosure to test the effect at a higher dose than the 250 mg cohort already reported. NCT07043946+1

The competitive frame

No industry-sponsored trial combines budoprutug's CD19 target with a B-cell depletion mechanism in an ITP program that has reached a resolved outcome. The closest direct comparator by target and phase is CRISPR Therapeutics' zugocabtagene geleucel, a CD19-directed cell therapy also in Phase 1/2 testing in ITP. Every other CD19-targeted asset in the broader landscape, including CAR-T and bispecific programs from Gilead, Merck, AstraZeneca, and Novartis, is being tested in lymphoma, leukemia, or lupus rather than ITP, and most use cell-therapy or bispecific modalities rather than a monoclonal antibody. Within ITP itself, the active field includes Novartis's ianalumab and Takeda's mezagitamab, both later-stage but neither sharing budoprutug's CD19 target. No comparable trial pairing CD19 with ITP has completed or terminated on record, so the interim platelet signal stands without a resolved same-target precedent to weigh it against.

Operational read

Enrollment has held flat at its 24-patient target with no growth or contraction, which the operational model treats as within the routine band for this design. The trial's registry history shows a single amendment since study initiation in June 2025, and no protocol instability signals. The primary completion date has not moved from August 2027 across the guidance updates issued since November 2025, so the H2 2026 window covers an interim look during an otherwise steady enrollment period rather than a change in trial timing.

This analysis was produced using AI-assisted reporting systems, AppliedXL data, and official public records. These systems undergo editorial review, quality checks, and regular audits by human experts. Errors may still occur, as with any automated system. Always consult the linked primary sources. Read our AI Editorial Policy.