Be Careful What You Wish For: Method of Treatment Claim for an Antibody Genus Found to Satisfy Both Written Description and Enablement Requirement (Teva v Eli Lilly)

Key Takeaways

• Federal Circuit upheld method‑of‑treatment claim for broad antibody genus
• Court distinguished written description and enablement for methods versus product claims
• Humanisation of known antibodies deemed routine, satisfying disclosure requirements
• Decision may signal US shift toward EPO‑style functional antibody claims
• Firms should add data proving therapeutic effect across the entire claim scope

Pulse Analysis

The Federal Circuit’s opinion in *Teva v. Eli Lilly* marks a pivotal moment for U.S. antibody patent law. Historically, the Supreme Court’s *Amgen v. Sanofi* decision forced patentees to disclose a representative set of species for any functional genus, effectively narrowing the scope of biologic claims. By contrast, the Federal Circuit treated the method‑of‑treatment claims as distinct from product claims, emphasizing that the underlying antibodies were already known and that humanisation was a routine step. This nuanced view sidestepped the “combination‑lock” analogy that had driven the enablement bar in earlier cases.

The court’s reasoning hinges on two practical observations. First, the specification disclosed that all humanised anti‑CGRP antibodies would treat migraine, allowing a reasonable jury to infer full enablement without exhaustive experimental data. Second, because the patents claimed only the therapeutic use—not the antibody sequences themselves—the written‑description requirement was satisfied by referencing the known class of anti‑CGRP antibodies. This creates a de‑facto split: broad functional claims may survive for methods of use even when product‑type claims would be invalidated, offering a new avenue for protecting biologics.

For biotech companies, the decision signals both opportunity and caution. While method‑of‑treatment patents can now capture a wider swath of competitor products, the burden shifts to demonstrating that the therapeutic effect holds across the entire claimed genus. Practitioners should consider bolstering applications with robust in‑vivo data and clear rationale that the effect is predictable for all variants. As the U.S. courts appear to inch toward an EPO‑style tolerance for functional antibody claims, strategic filing—balancing product and use claims—will become increasingly critical to maintaining market exclusivity.