Novartis Licenses Abogen's mRNA-Encoded CD19xCD3 T-Cell Engager ABO2203 for Autoimmune Diseases

Novartis has entered a licensing and option agreement with Abogen Biosciences that includes an exclusive worldwide license to ABO2203, an investigational mRNA-encoded CD19xCD3 T-cell engager (TCE) for autoimmune diseases, Abogen announced on Oct. 2, 2026.¹ Rather than delivering a recombinant bispecific antibody, ABO2203 uses mRNA to direct the body's own production of the TCE in vivo. The goal is to reset B cells in patients with B-cell-mediated disorders.¹ The agreement also gives Novartis exclusive options to license other programs built on Abogen's RNA platform.¹

How does ABO2203 work?

ABO2203 is a lipid nanoparticle (LNP)-formulated mRNA that encodes a bispecific TCE linking CD3 on T cells to CD19 on B cells.² Once the mRNA is translated, the expressed TCE is designed to redirect T cells to deplete B cells. Abogen describes this as a differentiated mechanism for B-cell depletion with potential advantages over traditional recombinant TCEs.¹ In a first-in-human oncology study, subcutaneously administered ABO2203 reached peak TCE concentration at 5.5 days and had a half-life of 7.9 days.²

"mRNA-encoded T-cell engagers represent an innovative approach that could complement existing therapeutic modalities by enabling in vivo production of these molecules," said Fiona Marshall, president of biomedical research at Novartis.¹

What clinical data exist for ABO2203?

According to Abogen, ABO2203 is the first mRNA-encoded TCE to enter clinical evaluation for autoimmune diseases.¹ A phase 1 study in China is evaluating its safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy. The study enrolls adults with refractory autoimmune diseases, including connective tissue diseases, who responded inadequately to standard treatment or relapsed.³ Sponsored by Ruijin Hospital, it began in December 2024 with planned enrollment of 66 participants.³ The agreement announcement does not report any autoimmune data.

The most detailed clinical data so far come from oncology. At the American Association for Cancer Research Annual Meeting 2026, Abogen presented preliminary dose-escalation results from 9 patients with relapsed or refractory B-cell non-Hodgkin lymphoma. These patients had received a median of 4 prior lines of therapy and had failed prior CD20-targeted therapy.² Objective response rates were 33%, 67%, and 100% in the low-, medium-, and high-dose groups, respectively.² No dose-limiting toxicities, cytokine release syndrome, or immune effector cell-associated neurotoxicity syndrome were observed, and grade 1 to 2 pyrexia was the most common adverse event.² These results come from a small, early dose-escalation cohort in a different disease setting.

Where do T-cell engagers and in vivo approaches fit in autoimmune disease?

TCEs are one of several B-cell-depleting approaches being explored in autoimmunity, including trispecific constructs such as Oblenio Bio's LBL-051, which targets CD3, CD19, and BCMA. In a 2024 video interview with BioPharm International®, Atul Mohindra, head of biologics R&D at Lonza, described the growth of bispecific formats in development. "Within the FDA-approved products, there's a minimal amount right now that … are bispecifics. However, when you look at the pipeline of products that are coming through in Phase I, Phase II, there's an enormous wave of these complex proteins that are coming through," Mohindra said.

Developers are also pursuing in vivo approaches for engineered cell therapies. In a 2023 BioPharm International feature on in vivo CAR T-cell therapy, Gregory Frost, chairman and chief executive officer of EXUMA Biotech, described one potential advantage of producing therapies inside the body. "Lymphodepletion may not be necessary for in vivo therapies, thereby potentially expanding the setting of care beyond tertiary care centers with intensive-care units and extending CAR therapy into indications not previously addressed (e.g., autoimmune disease) due to an unfavorable benefit-to-risk ratio," Frost said.

What are the terms of the agreement?

Abogen will receive an upfront payment of $575 million.¹ If Novartis exercises all options on all programs, Abogen is eligible for up to approximately $7.2 billion in potential development, regulatory, and commercial milestone payments, plus potential royalties on future product sales.¹ The transaction is subject to customary closing conditions, including required regulatory clearances.¹ Abogen's pipeline also includes ABO1108, a lyophilized mRNA shingles vaccine in Phase 3 trials in China.¹

References

1. Abogen Biosciences. Abogen Announces Licensing and Option Agreement with Novartis to Advance mRNA-Encoded T-Cell Engager and other potential RNA programs. Press release. Published October 2, 2026. Accessed October 2, 2026.
2. Abogen Biosciences. AACR 2026 Oral Presentation: Abogen Presents Preliminary Results of ABO2203 (mRNA-Encoded CD3×CD19 TCE) from First-in-Human Clinical Study in R/R B-NHL. Press release. Published April 20, 2026. Accessed October 2, 2026.
3. CenterWatch. A Study of mRNA Encoding CD19/CD3 T Cell Engager (ABO2203) in Patients With Refractory Autoimmune Diseases (NCT06747156). Accessed October 2, 2026.