Novartis has penned a $2 billion deal for a biotech whose next-gen anti-immunoglobulin E (IgE) program could offer a worthy successor to Xolair.
Excellergy has been snapped up by the Swiss pharma only five months after emerging with $70 million in funds. The Palo Alto, California-based biotech’s lead asset is an IgE antibody dubbed Exl-111, which is currently in phase 3 development. The drug is designed to disarm allergic effector cells at the source of activation.
Novartis is already a major player in the IgE space thanks to Xolair, which binds to IgE in the blood to prevent it from triggering allergic reactions. The Roche-partnered injectable anti-inflammatory antibody—which is approved for severe allergic asthma, chronic spontaneous urticaria, nasal polyps and food allergy—brought Novartis $1.7 billion in 2025 sales.
The deal for Excellergy this morning encompasses up to $2 billion across upfront and milestone payments, although the companies didn’t offer a breakdown of the financials.
Fiona Marshall, President of Biomedical Research at Novartis, said buying Excellergy “adds a differentiated next-generation anti-IgE program that builds on biology Novartis knows well, supported by preclinical evidence and early clinical pharmacokinetic data.”
“Exl-111 is designed to go beyond conventional anti-IgE therapy, with the potential to deliver faster and deeper suppression of IgE signaling as well as improved symptom control,” Marshall added. “This proposed acquisition strengthens our allergy portfolio and reflects our strategy of advancing innovative bold science to bring meaningful additional benefits to patients.”
Excellergy was formed back in 2021, with California-based Red Tree providing seed money for the startup. Since then, the biotech has been working on a potentially first-in-class drug type called effector cell response inhibitors (ECRIs) in hopes of ultimately redefining the standard of care for several allergic diseases.
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ECRIs are based on scientific advances related to the structural binding of IgE—a type of immune system antibody—discovered at Stanford University in California and the University of Bern in Switzerland.
The trifunctional ECRIs are designed to stop allergic responses at the source by directly removing IgE antibodies that are bound to the FceRI receptors without activating mast cells and basophils. The aim is to boost efficacy, speed up relief onset and offer complete control of allergic responses, according to the company.
A phase 1 study of Exl-111 kicked off last month on the back of preclinical research in monkeys showing a more than 99% removal of receptor-bound IgE from basophils. This demonstrated “active dissociation of cell-bound IgE,” Excellergy explained at the time.
Novartis said it sees potential to provide “earlier symptom relief, stronger disease control, more convenient dosing and broader use” across a range of IgE-mediated diseases like food allergy, chronic spontaneous urticaria, chronic inducible urticaria and allergic asthma.
Roche markets Xolair in the U.S.—where its patents have already lapsed—while Novartis owns the rights in the rest of the world. Roche has indicated that it expects biosimilar versions of Xolair, also known as omalizumab, to arrive in the U.S. around the second half of 2026, citing publicly available information in the market.
