Background
Biogen MA Inc. owns U.S. Patent No. 5,795,755 (’755 patent), which claims a method of treating multiple sclerosis, viral conditions, and certain cancers by administering “a pharmaceutically effective amount of a recombinant polypeptide” related to human interferon-β (IFN-β). IFN-β is a naturally occurring protein; the patent covers a method using a recombinantly produced version of the protein.
Biogen sued EMD Serono (maker of Rebif, a recombinant IFN-β product for treating multiple sclerosis), alleging induced and contributory infringement. Serono defended on invalidity grounds, arguing that the ’755 patent was anticipated by prior art disclosing the same treatment method using native (non-recombinant) IFN-β. Biogen countered that the limitation “recombinant polypeptide” distinguished the claimed method from the prior art, since the prior art used naturally derived rather than recombinantly produced protein. The district court granted judgment as a matter of law for Biogen, overturning a jury verdict of invalidity.
The Court’s Holding
The Federal Circuit reversed. Writing for a unanimous panel, Judge Linn held that when a method claim contains a “source limitation” — a term that describes how a product was made rather than what it is — the novelty of that limitation is governed by the same rule that applies to product-by-process claims: the source of production cannot confer novelty if the resulting product is structurally identical to a prior art product. Because the native and recombinant IFN-β molecules were structurally identical, the “recombinant” characterization did not distinguish the claimed method from the prior art method using native protein.
The court rejected Biogen’s argument that product-by-process principles apply only to product claims and not to method claims embedding a process limitation on a product ingredient. The Federal Circuit saw “no logical reason” why nesting a product-by-process limitation within a method claim should change how novelty is evaluated. The prior art disclosed the same treatment method using the same structurally identical molecule — the source of that molecule (recombinant vs. native) was irrelevant to anticipation. The jury verdict of invalidity was reinstated.
Key Takeaways
- A source limitation (e.g., “recombinant,” “purified,” “isolated”) in a patent claim cannot distinguish a structurally identical compound from prior art — the analysis mirrors the product-by-process rule.
- This rule applies even when the source limitation appears inside a method claim rather than in a product claim — the form of the claim does not change the novelty analysis for the limited element.
- Patent drafters seeking to protect recombinant biologics must claim structural, functional, or compositional differences from native molecules — labeling something “recombinant” alone is insufficient if the molecule itself is known.
- The decision has significant implications for biologic and biosimilar patent strategy, reinforcing that biological product patents must be grounded in characteristics of the molecule, not just its method of production.
Why It Matters
Biogen v. EMD Serono has broad implications for the pharmaceutical and biotech industries, where many patents on biologics describe their claims in terms of how the active ingredient was made (e.g., “recombinantly produced,” “cell culture-derived”) rather than what the molecule actually is. The decision confirms that such source-based claim language does not insulate a patent from prior art that disclosed the same molecule obtained through a different method.
For biosimilar and generic drug developers, the ruling provides a powerful invalidity argument against patents claiming well-known biologics using recombinant source language as the distinguishing feature. For innovator pharmaceutical companies, it signals that biologic patents must be carefully drafted to anchor novelty in the structure, function, or activity of the molecule — not merely in the recombinant production process. The case also reinforces the Federal Circuit’s consistent stance that patent law does not protect a prior-known compound simply because it is now made through a new production method.