China-based Abogen Biosciences presented preliminary Phase I clinical results at the AACR Annual Meeting 2026 in San Diego, from a first-in-human dose-escalation study of its mRNA-encoded CD3×CD19 bispecific T-cell engager, ABO2203, in relapsed/refractory B-cell non-Hodgkin lymphoma. Interim data from nine patients showed dose-dependent objective response rates, with no cases of cytokine release syndrome observed across all evaluated dose levels, the company said. The data were presented in an oral session by Professor Li Wang of Ruijin Hospital, Shanghai Jiao Tong University School of Medicine.
Across the nine patients enrolled in the dose-escalation stage, ORR reached 33%, 67%, and 100% in the low-, medium-, and high-dose cohorts, respectively, assessed by Lugano 2014 criteria. Complete metabolic responses were observed in both the medium- and high-dose cohorts, with a 100% complete response rate reported in the high-dose group. Responses spanned both aggressive histologies, including diffuse large B-cell lymphoma, and indolent subtypes — follicular lymphoma, mantle cell lymphoma, and marginal zone lymphoma — with a 100% ORR reported in follicular lymphoma patients. No dose-limiting toxicities, CRS, or immune effector cell-associated neurotoxicity syndrome were observed. The most common adverse event was Grade 1–2 pyrexia without clinically meaningful changes in oxygen saturation or blood pressure. Liver enzyme elevations were limited to Grade 1 and occurred at low incidence. Grade 3/4 events were infrequent and primarily hematologic. The maximum tolerated dose had not been reached at the time of data presentation. Pharmacokinetic analysis detected TCE expression across all three dose cohorts, with a time to peak concentration of 5.5 days and a half-life of 7.9 days, supporting an initial once-weekly dosing schedule with potential extension to every two to four weeks following response.
The first-in-human study (NCT07072169) is an open-label dose-escalation and expansion trial enrolling patients with relapsed/refractory CD19-positive B-NHL. The nine patients reported here had received a median of four prior lines of therapy and all had failed prior CD20-targeted treatment. ABO2203 was administered subcutaneously at dose levels ranging from 3 µg to 1,920 µg. These data are preliminary and drawn from the dose-escalation stage only; the expansion cohort has not been reported. No duration-of-response or progression-free survival data were reported at this readout.
ABO2203 is a lipid nanoparticle-formulated mRNA construct encoding a CD3×CD19 bispecific T-cell engager, designed to produce the TCE protein in vivo rather than administering it as a preformed biologic. In the R/R B-NHL setting, established CD20×CD3 bispecific antibodies provide a reference point: epcoritamab (Tepkinly) reported an ORR of 82% in relapsed/refractory follicular lymphoma after two or more prior lines in the EPCORE NHL-1 study (NCT03625037). Cross-trial comparisons are limited by differences in study design, duration, patient populations, and the early-stage, small-sample nature of the ABO2203 dataset.
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