Innovent Biologics and Spero Therapeutics have signed a $1.1 billion licensing deal for IBI355, a phase 2-ready Fc-silent anti-CD40L antibody planned for testing in IgG4-related disease and Sjögren's disease.
Innovent Biologics, a China-based biopharmaceutical company, and Spero Therapeutics, a US-based clinical-stage biopharma company, have entered an
The agreement, announced July 14, 2026, is valued at approximately $1.1 billion in upfront and milestone payments plus tiered royalties. The deal positions Fc-silent CD40L blockade, a mechanism once sidelined by safety concerns, for renewed testing in 2 chronic autoimmune diseases with no approved systemic therapies.¹
"CD40L is an important upstream mediator of immune activation and T-cell/B-cell collaboration, both of which are relevant to IgG4-RD progression [immunoglobulin G4-related disease]," said
"IgG4-related disease, Sjögren's disease, and other autoimmune conditions impose significant burdens on patients worldwide, with many facing limited treatment options," said
Spero plans to begin a
In addition to the upfront payment, Innovent is eligible for development, regulatory, and commercial milestones plus royalties on net sales in Spero's territories. The deal continues a broader pattern of Chinese biotechs out-licensing clinical-stage immunology assets to Western partners.¹
IgG4-RD is a fibroinflammatory condition affecting the pancreas, salivary and lacrimal glands, kidneys, and lungs, often requiring prolonged glucocorticoid courses with cumulative toxicity.¹,² Relapse is common during steroid tapering, and rituximab, the most established steroid-sparing option, depletes B cells broadly rather than targeting a specific costimulatory signal.3
SjD has no FDA-approved disease-modifying therapy despite affecting an estimated 43 to 60 per 100,000 people, disproportionately women.4 Management remains largely symptomatic, and systemic complications are typically treated with immunosuppressants adapted from other rheumatic diseases rather than SjD-specific agents.
IBI355 blocks CD40L, a costimulatory protein that drives T-cell and B-cell activation and has been implicated in fibrosis and autoantibody production across immune-mediated diseases. Unlike B-cell-depleting antibodies such as rituximab, CD40L blockade aims to interrupt this signal upstream without eliminating B cells outright.¹
Earlier anti-CD40L antibodies, including ruplizumab and toralizumab, showed clinical activity in lupus roughly 2 decades ago but were discontinued after causing thromboembolic events linked to Fc-mediated platelet activation.5 IBI355 is engineered as Fc-silent specifically to avoid that pathway, following a design strategy shared by newer-generation CD40L antibodies now in development.
The transaction's size may reflect a renewed confidence in the CD40L blockade approach following its early clinical setbacks, based on the premise that Fc engineering has resolved the platelet-activation problem that halted first-generation candidates.1 Researchers have described a resurgence of interest in the CD40-CD40L pathway as a non-B-cell-depleting immunomodulatory strategy.5
IBI355 has not been tested in a randomized, placebo-controlled efficacy trial in either indication, however. The phase 1b SjD data cited by the companies come from an open-label, dose-escalation study, which can establish safety and pharmacodynamic signals but not necessarily efficacy against placebo.¹
No efficacy data in IgG4-RD have been reported for IBI355, and the planned phase 2 trials have not yet enrolled patients. Full phase 1 and phase 1b safety data, including thromboembolic monitoring specific to this drug class, have not been published in a peer-reviewed journal.
Regulatory pathways for both indications remain undefined given the absence of approved therapies to serve as precedent. Innovent and Spero said additional details on trial design will be disclosed closer to the planned 2027 initiation dates.¹
