Welcome to the Big Molecule Watch!

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Goodwin’s award-winning Big Molecule Watch is the best resource for daily updates and analyses of regulatory issues, litigation, legislation, and other news in the world of biologics, biosimilars and related technologies. The editors of this blog have collectively been watching and engaging with the world of biologics and biosimilars (“big molecules”) since before the inception of the biosimilar industry in the U.S.  With extensive experience representing clients at all stages of a biologic’s or biosimilar’s lifecycle, from research and development, to patents, to regulatory application and approval, and through litigation and appeals, we are excited to share our observations and insights as the industry and the law continues to develop in this exciting area.

This blog focuses on “big molecules” as opposed to “small molecules.” Small molecule drugs have low molecular weight, a simple and well-defined structure, and are chemically synthesized. In contrast, “big molecule” drugs have high molecular weight, complex structures, and are derived from living organisms. For example, aspirin is small molecule while a monoclonal antibody is a big molecule. For further reading on big molecules, consider FDA's resources on biologics.

FDA Revises Draft Guidance on Substantial Evidence of Effectiveness to Clarify Confirmatory Evidence Requirements for a Single Clinical Investigation

On June 25, 2026, the U.S. Food and Drug Administration (FDA) announced the availability of revised draft guidance titled “Demonstrating Substantial Evidence of Effectiveness for Human Drug and Biological Products.”  The original draft guidance was issued in December 2019.  When finalized, the revised draft guidance will replace the FDA’s 1998…

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Fresenius Kabi and Dr. Reddy’s Announce FDA Approval of Rituximab Biosimilar

On August 1, 2026, Fresenius Kabi and Dr. Reddy’s Laboratories announced that the FDA had approved Dr. Reddy’s rituximab biosimilar, a biosimilar to Genentech’s RITUXAN® (rituximab).  Rituximab is a monoclonal antibody that targets the CD20 antigen expressed on B lymphocytes and is used in the treatment of several B-cell malignancies,…

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Genentech Files BPCIA Patent Infringement Suit Against Biocon Over Proposed PERJETA Biosimilar

On July 29, 2026, Genentech, Inc. (“Genentech”) and Hoffmann-La Roche Inc. filed a complaint in the U.S. District Court for the District of New Jersey against Biocon Biologics Inc. (“Biocon”) and related entities, alleging infringement of 28 patents relating to Genentech’s PERJETA and Biocon’s proposed biosimilar, Bmab1500. As we previously…

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Celltrion Targets European Secukinumab Market with EMA Filing for CT-P55

Celltrion has submitted a Marketing Authorization Application to the European Medicines Agency (“EMA”) for CT-P55, its biosimilar to Novartis’ COSENTYX® (secukinumab). The application covers all indications held by COSENTYX® in Europe, including plaque psoriasis, psoriatic arthritis, axial spondyloarthritis, juvenile idiopathic arthritis, and hidradenitis suppurativa. According to Celltrion, CT-P55 has demonstrated…

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