Protecting antibody innovations beyond composition claims

Yet many companies still anchor their patent portfolios around a single category: composition-of-matter claims to the antibody sequence itself. Recent court decisions highlight how that approach is no longer sufficient.

The composition claim is under pressure

For decades, broad functional genus claims — claiming all antibodies that bind a given target or perform a given function — were the gold standard of antibody IP. Historically, innovators could claim far more than they had reduced to practice. In the wake of the US Supreme Court's unanimous 2023 decision in Amgen v. Sanofi, other courts have adopted its reasoning to strike down functional genus antibody claims for lacking enablement or written description. The Court held that Amgen's patents were invalid for lack of enablement, characterising them in the Court's words as little more than a "research assignment." The era of broad functional composition claiming is decidedly over.

This means that companies relying primarily on composition claims face a strategic gap. Narrow sequence claims are easier to defend but simpler for competitors to design around. Broader functional claims now face a much higher evidentiary bar. Securing meaningful patent protection for antibody therapeutics now demands a rethinking of traditional approaches.

Method-of-treatment claims: the overlooked asset

If composition claims are narrowing, where does durable protection come from? One powerful answer lies in method-of-treatment and second medical use claims.

The recent Teva v. Eli Lilly case illustrates this vividly. Teva's patents were directed to methods of treating headache using humanised anti-CGRP antagonist antibodies, which were marketed as its migraine treatment Ajovy®. A jury found that Eli Lilly wilfully infringed the asserted claims by selling its rival drug Emgality® for the same purpose. The Federal Circuit reversed a district court ruling that had overturned the jury verdict, reinstating Teva's win and the $177 million in damages (Teva reported US sales of $295M for Ajovy® in 2025).

Critically, the court held that when a patent claims a method of using a well-known genus of compounds rather than claiming the compounds themselves, both the written description and enablement requirements are evaluated differently. In other words, medical use claims are not subject to the same constraints that Amgen v. Sanofi imposed on composition genus claims.

Notably, the PTAB had upheld Teva's three method-of-treatment patents while finding three composition-of-matter patents invalid — a stark illustration of why portfolios built on composition claims alone are exposed.

For antibody developers with products spanning multiple indications, each new therapeutic use — whether a new disease area, a new patient population, or a new dosage regimen — represents a filing opportunity that can extend protection well beyond the life of the original sequence claims.

Manufacturing patents: the most underused weapon

The second major area of untapped value is manufacturing process patents. This may seem counterintuitive — companies have historically preferred trade secrets for manufacturing methods, reluctant to disclose proprietary processes in exchange for a time-limited monopoly.

However, that equation has changed fundamentally in the era of biosimilar competition. Under the US Biologics Price Competition and Innovation Act (BPCIA), a biosimilar applicant's abbreviated biologics license application (aBLA) must contain a full description of its manufacturing methods, and the regulatory approval process requires this information to be shared with the originator company. The practical difficulty of detecting how a competitor manufactures its product — which historically made manufacturing patents hard to enforce — has been addressed by the BPCIA's disclosure requirements.

The litigation data confirms the shift. A typical BPCIA proceeding now involves around 20 asserted patents, though the range is wide — from a single patent in some cases to more than 60 in others. Among the most frequently asserted are manufacturing-related patents covering cell culture, media composition, and protein purification. Because the way a biologic is made so profoundly shapes the final product, protecting production methods can be as valuable as — or even more valuable than — protecting the antibody sequence. This contrasts sharply with traditional pharmaceutical IP, where patents typically centre on the active compound's chemical structure.

Despite this, the evidence suggests most companies have not adjusted their filing strategies. Companies should review existing portfolios for manufacturing method claims that could be filed, and reconsider innovations currently held as trade secrets.

Building a layered portfolio

An effective antibody IP strategy should therefore extend well beyond the antibody sequence to encompass multiple layers of protection:

• Composition claims to the antibody, its variants, and formulations — carefully scoped with adequate structural and experimental support;
• Method-of-treatment claims covering indications, dosage regimens, patient populations, and combination therapies — rather than speculatively listing every possible indication, dosage, administration route and combination therapy etc. in the composition patent, this subject matter should be included as clinical evidence supports specific therapeutic uses;
• Manufacturing process claims covering cell culture, purification, post-translational modification control, and formulation methods; and
• Delivery and device claims where relevant, particularly for subcutaneous and intravitreal products.

Biologic innovations offer numerous avenues for patent protection — from the therapeutic target and binding epitope to the antibody's sequence, three-dimensional structure, clinical applications, and production processes. Yet the legal landscape governing these claims remains unsettled and continues to evolve. Innovators must carefully navigate the squeeze between sufficiency and inventiveness requirements, all while accounting for divergent patentability standards across different patent offices.

Companies should also remember that regulatory and data exclusivity can complement the patent portfolio, particularly as core composition patents approach expiry.

Timing matters

As with any fast-moving therapeutic area, the timing of patent filings is critical. Early filings secure priority but may lack the experimental data needed to support broader claims. A staggered approach — filing initially on the core antibody, followed by subsequent applications as clinical data, new indications, and manufacturing optimisations emerge — allows companies to build portfolio depth over the product lifecycle.

Conclusion

The antibody IP landscape has shifted. Composition claims remain foundational but are no longer the fortress they once were. As the Teva v. Lilly case demonstrated, method-of-treatment patents proved both valid and enforceable — even where the competitor's antibody was structurally different. Meanwhile, the BPCIA has transformed manufacturing patents from an afterthought into the most frequently asserted category in US biosimilar litigation.

Companies that build multi-layered portfolios spanning composition, use, manufacturing, and formulation — and that time their filings to align with clinical and regulatory milestones — will be best positioned to protect their antibody innovations from discovery through to loss of exclusivity.