Otsuka Expands Autoimmune Portfolio with $613M Cantargia Deal

Otsuka Pharmaceutical has made a significant move to bolster its presence in the autoimmune and inflammatory disease space, signing a $613 million deal with Swedish biotech Cantargia for its IL1RAP antibody program. The agreement, announced on July 15, 2025, marks a substantial investment in novel therapies targeting autoimmune conditions and underscores Otsuka's commitment to expanding its immunology pipeline.

Deal Structure and Financial Terms

Under the terms of the agreement, Otsuka will pay Cantargia an upfront cash payment of $33 million, with the potential for up to $580 million in additional milestone payments. The deal also includes provisions for royalties on potential global sales. In exchange, Otsuka gains global development and commercialization rights to Cantargia's CAN10 program, which centers on antibodies targeting IL1RAP (Interleukin-1 Receptor Accessory Protein).

The partnership extends beyond CAN10, with Otsuka also acquiring rights to a preclinical "backup antibody" similar to CAN10. Furthermore, the Japanese pharmaceutical company has secured exclusive first negotiation rights for any next-generation IL1RAP antibodies developed by Cantargia within the next two years.

CAN10 Program and Clinical Progress

At the heart of the deal is Cantargia's CAN10 program, which is currently being evaluated in a phase 1 clinical trial for hidradenitis suppurativa, a chronic skin condition characterized by painful lumps. The company is also exploring the potential of CAN10 in systemic sclerosis, highlighting the broad applicability of IL1RAP-targeting therapies in various autoimmune and inflammatory conditions.

Cantargia's approach leverages its proprietary IL1RAP-based antibody platform, which the company claims can rapidly generate new therapies across multiple indications. This platform technology has already yielded nadunolimab (CAN04), Cantargia's most advanced asset, currently in mid-stage trials combining with chemotherapy for various cancers.

Strategic Implications for Otsuka

For Otsuka, this deal represents a significant expansion of its autoimmune R&D pipeline. Makoto Inoue, President and Representative Director of Otsuka Pharmaceutical, emphasized the strategic importance of the acquisition, stating that it aligns with the company's focus on autoimmune diseases.

This move follows closely on the heels of another recent deal in the autoimmune space. Just last month, Otsuka secured rights to a preclinical bispecific T-cell engager from Harbour BioMed in a separate agreement worth over $600 million in potential milestone payments. The rapid succession of these deals underscores Otsuka's aggressive push into the autoimmune therapeutic area.

Otsuka is not limiting its autoimmune research to external partnerships. The company is also leveraging internal resources, including the antibody-drug conjugate platform of its subsidiary Visterra and the small-molecule expertise of Jnana Therapeutics, to further strengthen its position in this competitive field.