GSK has entered into a definitive agreement to acquire 35Pharma Inc., a clinical-stage biotech company developing novel IL-1 inhibitors, for $950 million upfront with additional contingent payments. The deal brings 35Pharma’s lead asset, an anti-IL-1α/β bispecific antibody in Phase 2 for inflammatory diseases, into GSK’s immunology portfolio, strengthening its position in next-generation cytokine-targeted therapies.
Glimpse:
The $950 million all-cash transaction includes up to $1.4 billion in potential milestone payments tied to development, regulatory, and commercial achievements. 35Pharma’s lead candidate targets IL-1α and IL-1β simultaneously, offering potential advantages over existing IL-1 inhibitors in conditions such as hidradenitis suppurativa, gout, and other autoinflammatory diseases. The acquisition aligns with GSK’s strategy to build a differentiated immunology pipeline and is expected to close in the second half of 2026, subject to regulatory approvals.
GSK plc has announced a definitive agreement to acquire 35Pharma Inc., a privately held Belgian biotech company focused on developing innovative therapies targeting the IL-1 pathway, in a deal valued at $950 million upfront. The transaction, disclosed on February 26, 2026, also includes up to $1.4 billion in contingent milestone payments linked to development, regulatory, and sales achievements, bringing the total potential value to more than $2.35 billion.
35Pharma’s lead asset is a first-in-class bispecific antibody that simultaneously neutralizes both IL-1α and IL-1β, two key pro-inflammatory cytokines implicated in a range of autoinflammatory and autoimmune diseases. The molecule is currently in Phase 2 clinical development for hidradenitis suppurativa, with potential expansion into gout, recurrent pericarditis, and other IL-1-driven conditions. Preclinical and early clinical data suggest the dual blockade may offer superior efficacy and a differentiated safety profile compared to existing single-target IL-1 inhibitors such as anakinra, canakinumab, and rilonacept.
GSK’s Chief Scientific Officer Tony Wood stated that the acquisition aligns with the company’s strategy to build a world-leading immunology portfolio by targeting validated pathways with novel mechanisms. He highlighted that 35Pharma’s bispecific approach has the potential to deliver meaningful differentiation in difficult-to-treat inflammatory diseases where current therapies leave significant unmet need. The deal will integrate 35Pharma’s programs into GSK’s immunology R&D organization, leveraging GSK’s global clinical development, regulatory, and commercial capabilities to accelerate progress.
The transaction has been unanimously approved by the boards of both companies and is subject to customary closing conditions, including regulatory clearances under the Hart-Scott-Rodino Act and other applicable jurisdictions. It is expected to close in the second half of 2026. Following completion, 35Pharma’s operations will be integrated into GSK, with key scientific teams transitioning to support continued development of the IL-1α/β program.
The acquisition reflects GSK’s ongoing focus on high-value, first- or best-in-class assets in immunology, building on recent deals in autoimmune and inflammatory diseases. Industry analysts view the move positively, noting that dual IL-1 blockade represents a scientifically compelling next step in cytokine-targeted therapies, particularly given the proven role of IL-1 in multiple chronic inflammatory conditions.
“35Pharma’s innovative bispecific approach to IL-1 inhibition has the potential to transform treatment outcomes in serious inflammatory diseases. We are excited to bring this promising program into GSK and accelerate its path to patients.”
By
HB Team
