Patiromer – USA

Patiromer – USA

Relypsa, Inc. et al v. Alkem Laboratories Ltd. et al

Case : 20-106

Judge: Judge Maryellen Noreika

Court: District of Delaware

Date: Jul. 20, 2021 – Claim construction – US 8,147,873, US 8,337,824, US 9,492,476 and US 9,925,212


Agreed-upon constructions:

1. “cation exchange, crosslinked . . . polymer or a salt thereof” means “crosslinked polymer or a salt thereof that is able to exchange cations” (’873 Patent, claim 1)

2. “cation exchange polymer salt” means “polymer salt that is able to exchange cations” (’824 Patent, claims 1-2, 7-8, 52, 60-61 & 69)

3. “cation exchange polymer” means “polymer or salt thereof that is able to exchange cations” (’476 Patent, claim 1; ’212 Patent, claim 1)


Construction of the disputed claim term:

1. “wherein the alpha-fluoroacrylic acid polymer is crosslinked with divinylbenzene” shall be given its plain and ordinary meaning, which requires divinylbenzene to be a crosslinking agent but does not exclude other additional crosslinking agents (’873 Patent, claim 1)


Plaintiffs proposed that no construction is necessary. Defendants proposed “wherein divinylbenzene is the only crosslinking agent that links polymer chains of alpha-fluoroacrylic acid to one another.” The crux of the dispute was whether the term is limited to a polymer that is crosslinked with only divinylbenzene and no other crosslinking agent. Here, Court agreed with Plaintiffs that the term requires that divinylbenzene be a crosslinking agent, but it need not be the only crosslinking agent. This construction is supported by the ordinary meaning of the claim language itself, which requires that the alpha-fluoroacrylic acid polymer is crosslinked with divinylbenzene but does not state that the polymer is only crosslinked with divinylbenzene. And there is nothing in the specification that contradicts this meaning as it neither requires nor excludes the use of any one or more crosslinking agents. Prosecution history also does not require the claims to be limited to having divinylbenzene as the only crosslinker – either through repeated statements about the invention as Phillips counsels or as a clear and unmistakable disclaimer.

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