Enablement of Method of Treatment Claims

Published 6 October 20268 minute read

Can a patent claim to a method of treatment be enabled when the patent describes only one of the many antibodies it covers? In Teva v Lilly, the Federal Circuit said yes on the facts. The court has now refused to rehear the case en banc.

The ruling matters to every company that protects biologics in the United States. This article explains what the court decided, what it left open, and how the same invention would be claimed in each jurisdiction.

Key points

In Teva v Lilly (No. 24-1094, 16 April 2026), the Federal Circuit reversed a judgment that Teva’s method of treatment claims were invalid for lack of written description and enablement.
The claims covered using a known class of antibodies to treat headache. The court held they are not like the antibody genus claims struck down in Amgen v Sanofi.
Rehearing en banc was refused at the end of September 2026. Reports say Judge Dyk dissented.
Europe does not allow method of treatment claims. It protects medical uses through purpose limited product claims, and sufficiency is tested across the whole claim.
India excludes methods of treatment under section 3(i) and generally refuses use claims. Biologics must be protected by product and process claims that meet section 10(4).

The dispute

Teva sued Eli Lilly in the District of Massachusetts over patents on treating headache with anti CGRP antagonist antibodies. A representative claim covers a method of treating headache in a human by administering an effective amount of such an antibody. The antibody must be a humanized monoclonal antibody.

A jury found that Lilly willfully infringed and that Lilly had not proved the claims invalid. The trial judge then granted judgment as a matter of law that the claims were invalid. She held that they failed both the written description and the enablement requirements of 35 U.S.C. 112(a).

Lilly argued that the claims cover a vast number of humanized antibodies but the patent disclosed only one. After Amgen v Sanofi, it said, that could not be enough.

What the Federal Circuit decided

A panel of Judges Prost and Cunningham and District Judge Andrews reversed and remanded. Judge Prost wrote the opinion.

On written description, the court accepted that the specification disclosed just one humanized antibody. But it also disclosed several murine antibodies and known methods of humanization. Antibodies of this kind and ways to make them were already well known. Critically, a skilled reader would understand from the specification that all humanized anti CGRP antagonist antibodies treat headache. The jury could therefore find a representative number of species for the claimed invention.

On enablement, the court restated the familiar rule. The specification must teach the skilled person how to make and use the full scope of the claimed invention. The question was what that scope is when the claim is to a method of use.

The panel answered by looking at what was claimed. The claims did not cover the antibodies themselves. They covered only using them for the limited purpose of treating headache. The court said Lilly’s argument might be more persuasive if the claims were to the antibody genus itself. That case would resemble Amgen.

The court then rejected the idea that Teva had to show how to find or make every antibody in the class. It said such an effort would be “more akin to extra credit than a necessary research assignment left to others to complete.” It tied that view to the context of these claims.

Why this is not Amgen

In Amgen v Sanofi, 598 U.S. 594 (2023), the Supreme Court held invalid claims to a genus of antibodies defined by what they do. Amgen had described some antibodies and two methods for finding more. That left the skilled person to trial and error across a huge class. The more a patentee claims, the more it must enable.

The Amgen claims were to new antibodies whose identity was the invention. Teva’s claims assumed a class that skilled people could already make. The invention was a new use for that class. Amgen and Teva both turn on what the skilled person must still discover to practise the claim.

The en banc dissent

Lilly petitioned for rehearing. Reports of the order date the denial to 30 September 2026, with Judge Dyk dissenting. Those reports say he wrote that the panel decision creates confusion about enablement standards for method claims. He also argued about antibodies with no use other than treating headache. For them, he said, the practical scope of the method claim equals the scope of the compound.

That argument has force. A method claim to the only known use of a compound can give the same commercial control as a claim to the compound. Lilly may now ask the Supreme Court to take the case.

What the ruling does not decide

Teva v Lilly is not a licence to claim any class of molecules through a method claim. Three limits stand out.

The court reviewed a jury verdict. Written description is a question of fact, so it asked whether substantial evidence supported the jury. Enablement is a question of law, but its factual findings got the same deference.
The class was a known one. Making and humanizing these antibodies was routine, and the skilled person would expect all of them to work.
Teva did not argue that the specification disclosed structural features common to the class. The result rests on the use, not on structure.

How Europe treats the same invention

Under Article 53(c) EPC, methods for treatment of the human body by therapy are not patentable. Teva’s claims could not be granted in that form at the EPO or enforced at the UPC.

Europe instead allows purpose limited product claims under Articles 54(4) and 54(5) EPC. A new use of a known antibody class is a second medical use under Article 54(5). The claim would read as an antibody for use in treating headache. The therapeutic effect then becomes a technical feature of the claim.

Sufficiency under Article 83 EPC is tested across the whole claimed scope. The skilled person must be able to obtain substantially all antibodies within the class without undue burden. The application must also make the therapeutic effect credible on its filing date.

The United Kingdom applies a similar principle to product claims. In Regeneron v Kymab [2020] UKSC 27, the Supreme Court held that a product claim must be enabled across its whole range. A medical use claim to a broad antibody class would face both tests at the EPO and in national courts.

How India treats the same invention

India goes further. Section 3(i) of the Patents Act, 1970 excludes any process for the medicinal, surgical, curative, prophylactic, diagnostic, therapeutic or other treatment of human beings. A claim like Teva’s is not grantable in India.

The Indian Patent Office also generally refuses claims to the use of a known substance. Such claims are treated as neither a product nor a process. A new use of a known substance is also caught by section 3(d).

That leaves product and process claims. Section 10(4) requires the specification to describe the invention fully and particularly, and to disclose the best method known to the applicant. Section 10(5) requires the claims to be fairly based on that matter. Insufficiency is a ground of opposition under section 25. It is also a ground of revocation under section 64(1)(h). Lack of fair basis is a ground of revocation under section 64(1)(i).

In practice, Indian antibody claims are usually defined by structure. Claims set out sequences or binding regions and are supported by working examples. A functional class claim like Amgen’s would likely face sufficiency and fair basis objections in India. Our guide to filing a patent in India for foreign applicants explains how to adapt US claim sets before entry.

Practical steps for applicants

In the US, keep method of use claims in the portfolio alongside compound claims. Teva shows they may survive on some facts where genus product claims might not.
Explain in the specification why every member of the class is expected to work. The court gave weight to that understanding.
For Europe, file data that make the therapeutic effect credible across the claimed class on the filing date. Later evidence cannot cure insufficiency.
For India, draft structural product claims from the start, with fallback positions in the description. Do not rely on use or treatment claims.

Claim scope that works in one office may be unavailable in another. Our international patent support team aligns claim sets across the US, Europe and India from the priority filing. See also our guide to patent claim drafting for commercial value.

Frequently asked questions

Are method of treatment claims patentable in India?

No. Section 3(i) of the Patents Act, 1970 excludes processes for the therapeutic or other treatment of human beings. Applicants protect drugs and biologics in India through product and process claims instead.

Does Amgen v Sanofi apply to method of treatment claims?

The enablement rule applies to every claim. In Teva v Lilly, the claims covered using a known antibody class for one purpose. The Federal Circuit held they did not need the same enablement as claims to the antibodies themselves.

How does the EPO treat second medical use claims?

The EPO allows purpose limited product claims under Article 54(5) EPC. The application must make the therapeutic effect credible, and the skilled person must be able to work the claim across its scope.

Enablement of method of treatment claims after Teva v Lilly