Kali Therapeutics Licenses Tri-Specific T-Cell Engager to Sanofi

Kali Therapeutics, a US-based biotechnology company specializing in next-generation biologics, announced a worldwide exclusive licensing agreement on March 23, 2026 with Sanofi for KT501, a next-generation tri-specific T-cell engager (TCE) being developed for B cell–mediated autoimmune diseases.¹

Under the agreement, Sanofi will obtain global rights to KT501, while Kali Therapeutics will receive $180 million in upfront and near-term payments. The company also remains eligible for up to $1.05 billion in development and commercial milestones, along with tiered royalties on future sales.

The collaboration reflects growing biopharmaceutical interest in multi-specific TCE platforms as potential therapies for autoimmune diseases, for which targeted immune modulation remains a key unmet need. For example, earlier in March, Shanghai-based Excalipoint Therapeutics was launched with $68.7 million in seed financing, aimed at advancing proprietary TCE platforms and a pipeline of next-generation immunotherapies targeting oncology and autoimmune diseases.²

How do tri-specific TCEs expand autoimmune treatment strategies?

KT501 is an immunoglobulin G-like tri-specific antibody designed to simultaneously bind CD3, CD19, and B-cell maturation antigen, enabling depletion of a broad range of B cell populations implicated in autoimmune disease pathogenesis.

Unlike earlier TCE approaches primarily developed for oncology, KT501 incorporates a CD3 masking strategy intended to modulate T-cell activation and reduce cytokine release. This design aims to decouple therapeutic potency from toxicity, a central challenge in immune cell–redirecting therapies.

Preclinical data in non-human primate studies demonstrated robust B-cell depletion across peripheral and tissue compartments, alongside reduced cytokine production. These findings suggest the potential for sustained immunologic effects while mitigating safety risks commonly associated with T-cell engagement. The candidate is currently being evaluated in a first-in-human clinical study assessing safety, tolerability, pharmacokinetics, and pharmacodynamics in patients with rheumatoid arthritis, according to the company.¹

What role does platform engineering play in next-generation biologics?

Kali Therapeutics’ approach is based on a proprietary immune cell engager platform that integrates protein engineering and high-throughput experimental techniques to optimize functionality, manufacturability, and developability.

According to the company, this platform is designed to enable precise control of immune activation, particularly in the context of autoimmune diseases, in which excessive immune stimulation can lead to adverse effects. By targeting multiple antigens simultaneously while modulating CD3 engagement, tri-specific constructs may offer improved selectivity and therapeutic index compared to earlier modalities.³

"We are thrilled to collaborate with Sanofi, a global leader in immunology, to advance the development of KT501, our lead tri-specific program," said Weihao Xu, CEO of Kali Therapeutics in a company press release.¹ "Our platform leverages state-of-the-art protein engineering to solve complex therapeutic challenges. This collaboration highlights the potential of our unique CD3 masking technology to decouple potency from toxicity, aiming to provide safer, more effective options for patients."

"Autoimmune diseases require treatments that are not only highly potent but also exhibit a superior safety profile,” Xu added. “KT501 represents a significant leap forward in this regard. By depleting a broad range of B cell populations effectively while minimizing cytokine release, we believe KT501 can address significant unmet needs of autoimmune patients. We are confident that Sanofi's extensive expertise will accelerate the development of this promising therapy."

Why are large biopharma partnerships accelerating AI and biologics pipelines?

The Kali Therapeutics agreement highlights continued collaboration between emerging biotech platforms and large biopharmaceutical companies seeking access to differentiated biologics.

Sanofi recently expanded its external innovation strategy, including partnerships with AI-driven discovery platforms to accelerate biologics development. Prior to this deal, Sanofi took part in a large-scale investment in Earendil Labs for its AI-enabled biologics pipelines. That deal underscores growing emphasis on integrating advanced discovery technologies with global development capabilities.⁴

Such partnerships may help bridge early-stage innovation with late-stage development expertise, supporting the advancement of complex biologics such as multi-specific antibodies across therapeutic areas.

References

1. Kali Therapeutics. Kali Therapeutics announces worldwide exclusive license agreement with Sanofi for next-generation tri-specific t-cell engager for autoimmune diseases. Published March 23, 2026. Accessed March 23, 2026. https://www.kalitherapeutics.com/post/kali-therapeutics-announces-worldwide-exclusive-license-agreement-withsanofi-for-next-generation-tri
2. Excalipoint Therapeutics. Excalipoint Therapeutics Launches with $68.7 Million to Develop Next-Generation T-Cell Engager Therapies. Published March 18, 2026. Accessed March 18, 2026. https://www.businesswire.com/news/home/20260318260662/en/Excalipoint-Therapeutics-Launches-with-%2468.7-Million-to-Develop-Next-Generation-T-Cell-Engager-Therapies
3. Tapia-Galisteo A, Compte M, Álvarez-Vallina L, Sanz L. When three is not a crowd: trispecific antibodies for enhanced cancer immunotherapy. Theranostics. 2023;13(3):1028-1041. doi: 10.7150/thno.81494
4. Earendil Labs. Earendil Labs announces $787 million in financing to scale AI-driven biologics discovery and development. Published March 20, 2026. Accessed March 20, 2026. https://www.prnewswire.com/news-releases/earendil-labs-announces-787-million-in-financing-to-scale-ai-driven-biologics-discovery-and-development-302719748.html