Genentech v. Natco Pharma — Risdiplam Patent Term Does Not Import Every Specification Characteristic

Background

Genentech and Hoffmann-La Roche sued several generic-drug manufacturers over proposed generic versions of Evrysdi, the brand name for risdiplam. Risdiplam is an oral medicine used to treat spinal muscular atrophy. The consolidated litigation includes a claim that Natco Pharma and Sun Pharmaceutical infringed U.S. Patent No. 12,122,789 through an abbreviated new drug application, the regulatory pathway a manufacturer uses to seek approval for a generic drug.

The patent covers crystalline forms of risdiplam, including an anhydrous polymorph called “Form A.” A polymorph is a particular crystalline arrangement of a chemical compound. Different arrangements can affect properties important to drug production, such as stability, filtration, storage, and packaging. Before deciding infringement or validity, the court had to construe the disputed phrase “crystalline Form A”—that is, determine what the patent claims mean as a matter of law.

The patent owners argued that the specification expressly defined Form A and that each claim separately identified the characteristics required by that claim. The generic manufacturers proposed a narrower construction requiring Form A to possess all characteristics assigned to it anywhere in the specification.

The Court’s Holding

Judge Jennifer Choe-Groves, sitting by designation, rejected the generic manufacturers’ effort to import every described characteristic into the disputed term. The court construed “crystalline Form A” to mean the crystalline anhydrous polymorphic Form A of the chemical compound identified in the patent—risdiplam—using the patent specification’s express definition.

The court emphasized the distinction between construing claims in light of the specification and adding limitations from embodiments described there. The specification listed multiple Form A embodiments with different X-ray powder diffraction peaks and even described some peaks as optional. Reading every listed characteristic into the basic term would collapse those variations and add requirements that the claim language did not impose.

The structure of the claims reinforced that conclusion. Independent claim 1 identifies Form A and specifies selected diffraction peaks, while dependent claims add other combinations of characteristics. Treating the general term as already requiring every characteristic from the specification would undercut those separately stated limitations. The ruling resolves claim meaning only; it does not decide whether the defendants infringe or whether the patent is valid.

Key Takeaways

• An express definition in a patent specification can control claim meaning without pulling every disclosed embodiment or property into the claim.
• Courts generally resist constructions that make separately recited limitations in dependent claims redundant.
• The construction preserves a broader infringement inquiry for the risdiplam Form A claims, but the patent owners must still prove infringement and overcome any validity defenses.

Why It Matters

In pharmaceutical patent litigation, small differences in claim construction can determine whether a proposed generic product falls within a patent’s scope. Crystalline-form patents are especially sensitive because a compound can exist in several physical arrangements, each described through technical measurements and manufacturing properties.

This ruling illustrates a recurring drafting and litigation lesson: examples and preferred characteristics in a specification do not automatically become universal claim requirements. Patent owners benefit when the claims themselves identify which measurements matter, while accused infringers need a clear basis in the claim language or an unmistakable disclaimer before a court will narrow a term to every characteristic disclosed in the specification.