Biogen consolidates global felzartamab rights via USD 850m agreement with TJ Biopharma

Biogen (Nasdaq: BIIB) revealed a definitive agreement to acquire China-based TJ Biopharma's exclusive rights to felzartamab in the Greater China Region for up to USD 850 million in upfront and milestone payments, completing Biogen's consolidation of worldwide rights to the CD38-directed monoclonal antibody. The transaction extends Biogen's immunology franchise into one of the largest patient populations globally for IgA nephropathy and primary membranous nephropathy, two indications where felzartamab is currently enrolled in Phase III international multi-center trials.

Under the terms of the agreement, TJ Biopharma receives a USD 100 million upfront cash payment and is eligible for up to USD 750 million in commercial and sales milestone payments. TJ will also receive mid-single-digit to low-double-digit royalties on net sales in the Greater China Region. As part of the transaction, Biogen assumes milestone payment and royalty obligations under the prior licensing agreement with MorphoSys GmbH, a wholly-owned subsidiary of Novartis, which originally developed felzartamab. No development or regulatory milestone payments are disclosed in the current agreement.

Biogen previously held exclusive worldwide rights to felzartamab across all territories excluding Greater China, obtained through its acquisition of Human Immunology Biosciences in July 2024. This transaction closes the final geographic gap, placing exclusive worldwide development and commercialization rights under a single owner.

Felzartamab and CD38-directed plasma cell depletion

Felzartamab is a fully human monoclonal antibody directed against CD38, a protein expressed on plasma cells, plasmablasts, and natural killer cells. Its mechanism centers on selective depletion of CD38-positive plasma cells, the primary source of pathogenic antibodies in a range of immune-mediated kidney diseases. By reducing circulating autoantibody titers, felzartamab targets a mechanistic node relevant across IgA nephropathy, primary membranous nephropathy, lupus nephritis, and antibody-mediated rejection in kidney transplant recipients.

The breadth of this mechanism distinguishes felzartamab within the current nephrology treatment landscape. IgA nephropathy management has historically relied on supportive care, renin-angiotensin-aldosterone system blockade, and, more recently, targeted complement or endothelin pathway inhibition. Felzartamab's direct depletion of the pathogenic plasma cell compartment represents a distinct mechanistic approach. In primary membranous nephropathy, where anti-phospholipase A2 receptor antibodies drive podocyte injury, CD38-directed depletion of the antibody-secreting cell population addresses the upstream source of disease rather than downstream inflammatory sequelae.

Biogen is currently conducting Phase III trials in IgA nephropathy and primary membranous nephropathy, and has initiated a Phase III study in antibody-mediated rejection in kidney transplant recipients. A Phase I study in lupus nephritis is active. TJ Biopharma joined two Biogen-sponsored Phase III international multi-center trials evaluating felzartamab in IgA nephropathy and primary membranous nephropathy in China in April 2025, providing the clinical collaboration infrastructure that preceded this rights consolidation.

Separately, a Biologics License Application for felzartamab in multiple myeloma, submitted by TJ Biopharma to China's National Medical Products Administration in December 2024, is currently under regulatory review. Biogen will lead post-approval commercial efforts in the region for that indication, while TJ Bio will serve as the manufacturer for the multiple myeloma indication at its Hangzhou GMP facility.

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