Eli Lilly and Co v. Apotex, Inc. (Fed. Cir. 2020)
You don’t see this often — the district court held on summary judgment that Apotex infringes under the doctrine of equivalents. On appeal, the Federal Circuit has affirmed – finding no error. (Nonprecedential opinion)
Lilly’s US7772209 claims a particular treatment scheme for pemetrexed disodium that includes a pre-treatment with folic-acid to avoid the harsh side-effects. See, Crouch, Eligibility Cannot be Raised in IPR Appeal (2019). Apotex’s product uses a slightly different salt – pemetrexed dipotassium. Apotex needs its version to be the equivalent in order to receive drug approval, but it would prefer to still avoid infringement under the Doctrine of Equivalents.
Although Apotex (implicitly) admits that its version is an equivalent, the company argues that Lilly should be estopped from pursuing DoE infringement here because of Prosecution History Estoppel (PHE). In particular, Lilly made a narrowing amendment to the claim term in question during patent prosecution to avoid the prior art and now seeks to reclaim that ground via equivalents.
My simplistic drawing above does the trick. Lilly’s original patent filing did not expressly claim the use of “pemetrexed disodium,” but rather used the broader term “an antifolate.” During prosecution, Lilly narrowed its claims to avoid some prior art — deleting the broader “antifolate” limitation and replacing it with the narrower “pemetrexed disodium.”
None of the dependent claims expressly recited Pemetrexed Disodium. However, one original claim had limited the antifolate to “ALIMTA,” which is Lilly’s brand of Pemetrexed Disodium. In addition, the specification noted that the “most preferred” antifolate for the practicing the invention is “Pemetrexed Disodium (ALIMTA), as manufactured by Eli Lilly & Co.” The claim to ALIMTA was also deleted during prosecution based upon an indefiniteness rejection. MPEP 2173.05(u).
PHE: We know that a narrowing amendment made during prosecution creates a presumption of Prosecution History Estoppel that would bar the patentee from asserting infringement-by-equivalents over the surrendered subject-matter.
The district court found no surrender, and the Federal Circuit affirmed. The first bit here is easy claim construction — the original (dependent) claim recited “ALIMTA” and now the claim recites “pemetrexed disodium.” The district court found these to be synonymous, and the federal circuit agreed. Apotex had argued that ALIMTA should have been seen as encompassing all forms of pemetrexed, and thus its deletion would serve as an additional narrowing amendment. The courts, however, rejected that argument based upon in intrinsic evidence within the patent documents. This was the sole argument raised on appeal by Apotex and thus lost the case.
The court does not address PHE stemming from the bigger amendment (antifolate => pemetrexed disodium). There was a continuation application in-between, but you “can’t use continuations to avoid fact of narrowing amendment.” Robert A. Matthews, 2 Annotated Patent Digest § 14:82.