The Federal Circuit recently issued a significant decision in the ongoing patent litigation between Laboratory Corporation of America Holdings (Labcorp) and Qiagen Sciences, LLC, reversing a Delaware district court’s judgment that had found Qiagen liable for infringement of Labcorp’s patents-at-issue. In doing so, it vacated the $4.7 million damages award against Qiagen and ordered the district court to grant judgment as a matter of law (JMOL) of non-infringement.

Background

The patents-at-issue — U.S. Patent No. 10,017,810 and U.S. Patent No. 10,450,597 — cover methods for preparing DNA samples for sequencing, with a focus on “enrichment” techniques that allow researchers to selectively amplify regions of interest in a DNA sample. Labcorp (as successor to ArcherDX and Massachusetts General Hospital) alleged that Qiagen’s DNA preparation kits infringed claims of both patents.

With respect to the ʼ810 patent, representative claim 16 reads as follows:

16. A method for preparing a nucleic acid for sequencing, the method comprising:

(i) ligating a universal oligonucleotide tail adaptor that comprises a first ligatable duplex end and a second unpaired end to a nucleic acid comprising a known target nucleotide sequence to produce a ligation product, the universal oligonucleotide tail adaptor comprising an amplification strand and a blocking strand, wherein a 3′ duplex portion of the amplification strand and a 5′ duplex portion of the blocking strand are substantially complementary and form the first ligatable duplex end;

(ii) amplifying the ligation product using a first target-specific primer that specifically anneals to the known target nucleotide sequence and a first adaptor primer having a nucleotide sequence identical to a first portion of the amplification strand; and

(iii) amplifying an amplification product of (ii) using a second target-specific primer that specifically anneals to the amplification product of (ii) and a second adaptor primer having a nucleotide sequence identical to a second portion of the amplification strand, wherein ligating in step (i) comprises performing an overhang ligation reaction, and wherein the universal oligonucleotide tail adaptor further comprises a barcode portion.

The district court construed the term “second target-specific primer” to mean “a single-stranded oligonucleotide comprising a 3′ portion comprising a nucleic acid sequence that can specifically anneal to a portion of the known target nucleotide sequence comprised by the amplicon resulting from step (b), and a 5′ portion comprising a nucleic acid sequence that is identical to a second sequencing primer.” The term “second adaptor primer” was construed to mean “a nucleic acid molecule comprising a nucleic acid sequence identical to a portion of the first sequencing primer and is nested with respect to the first adaptor primer.”

With respect to the ʼ597 patent, claim 1 was considered representative and reads as follows:

1. A method of preparing nucleic acids for analysis, the method comprising:

(a) contacting a first nucleic acid template comprising a sequence of a first strand of a double-stranded target nucleic acid with a complementary target-specific primer that comprises a target-specific hybridization sequence, under conditions to promote template-specific hybridization and extension of the target-specific primer;

(b) contacting a second nucleic acid template comprising a sequence of a second strand that is complementary to the sequence of the first strand of the double-stranded target nucleic acid with a plurality of different primers that share a common sequence that is 5′ to different hybridization sequences, under conditions to promote template-specific hybridization and extension of at least one of the plurality of different primers, wherein the different hybridization sequences have different 3′ ends, and wherein each primer of the plurality of different primers does not anneal to the same sequence of the double-stranded target nucleic acid as any other primer of the plurality of different primers,

wherein, following (a) and (b), an extension product is generated to contain both a sequence that is characteristic of the target-specific primer and a sequence that is characteristic of the at least one of the plurality of different primers; and

(c) subjecting the extension product to an amplification reaction comprising successive rounds of polymerase extension of i) a tail primer that comprises a 3′ sequence that specifically anneals to the complement of the common sequence and that comprises a 5′ tail sequence, and ii) a primer that specifically anneals to the complement of the target-specific hybridization sequence.

The term “target-specific primer” was construed to mean “a primer that has a level of complementarity between the primer and the target such that . . . the primer will anneal to and mediate amplification of the tar-get nucleic acid and will not anneal to or mediate amplification of non-target sequences present in a sample.” 

After a five-day trial, a Delaware jury found that Qiagen willfully infringed the asserted claims of both patents and awarded Labcorp $4.7 million in damages. The district court denied Qiagen’s post-trial motions for JMOL and for a new trial, prompting Qiagen’s appeal.

The Appeal

The Federal Circuit’s opinion focused on whether there was sufficient evidence to support the jury’s findings of infringement under the proper claim constructions. To cut to the chase, the panel found that there was insufficient evidence from which a reasonable jury could have found liability. The court’s analysis addressed both patents separately.

The ’810 Patent: “Identical” Does Not Mean “Identical to a Portion” and No Substantial Similarity

A central issue for the ’810 patent was the construction of the term “identical” in the context of a “second target-specific primer.” The district court had allowed the jury to decide whether a primer that was “identical to a portion” of another sequence could satisfy the claim requirement of being “identical.” The Federal Circuit panel found this was error, emphasizing that claim construction is a matter of law for the court, not a factual issue for the jury:

When the parties raise an actual dispute regarding the proper scope of these claims, the court, not the jury, must resolve that dispute.

The panel explained that “identical” means “the same,” not “identical to a portion,” and that, because the patent’s specification and claim language distinguished between “identical” and “identical to a portion,” conflating the two would render the claim language superfluous. Because Qiagen’s accused product only matched a portion of the claimed sequence, the court found that no reasonable jury could have found infringement under the correct construction.

Moreover, the Federal Circuit rejected the jury’s finding of infringement under the doctrine of equivalents, finding that Labcorp failed to provide the required “particularized testimony and linking argument” to show that Qiagen’s product performed substantially the same function, in the same way, to achieve the same result as the claimed invention. The court found that the accused primer in Qiagen’s kit did not enrich the target sequence or provide specificity as required by the claims of the ʼ810 patent, and thus could not be considered equivalent.

The ’597 Patent: “Target-Specific Primer” Requirement Not Met

For the ’597 patent, the court examined whether Qiagen’s “FP” primer met the claim requirement of a “target-specific primer.” The court found that the FP primer annealed to an artificial adaptor sequence common to all DNA fragments, not to the “nucleic acid to be analyzed” as required by the claims of the ʼ597 patent. The court also rejected Labcorp’s argument that the FP primer could satisfy the claim in combination with another primer, holding that the claim language required the “target-specific primer” to perform the function independently.

Takeaways

On remand, the district court is instructed to enter judgment of non-infringement in favor of Qiagen. The Federal Circuit’s opinion provides a clear reminder of the importance of careful claim drafting, rigorous claim construction, and the high evidentiary bar for proving infringement — especially under the doctrine of equivalents:

• Claim Construction Is for the Court – Disputes over the meaning of claim terms must be resolved by the court as a matter of law, not left to the jury as factual questions.
• Precision in Claim Language Matters – The Federal Circuit will generally enforce distinctions in claim language, such as “identical” versus “identical to a portion,” and broader interpretations that render claim terms superfluous will not be viewed favorably.
• Doctrine of Equivalents Requires Specific Evidence – To prove infringement under the doctrine of equivalents, patentees must provide detailed, limitation-specific evidence showing substantial similarity in function, way, and result.
• Independent Functionality Requirements – Where claims require a specific element to perform a function, patentees cannot rely on the combined action of multiple elements to satisfy that requirement.

Listen to this post