Kalydeco® (ivacaftor)
Case Name: Vertex Pharms. Inc. v. Lupin Ltd., No. 22-cv-966-SB, 2026 WL 2474714 (D. Del. Aug. 24, 2026) (Bibas, J.)
Drug Product and Patent(s)-in-Suit: Kalydeco® (ivacaftor); U.S. Patent Nos. 10,646,481 (“the ’481 patent”), 11,564,916 (“the ’916 patent”), 12,458,635 (“the ’635 patent”), and 10,272,046 (“the ’046 patent”)
Nature of the Case and Issue(s) Presented: Kalydeco is Vertex’s ivacaftor drug for treating cystic fibrosis. Because ivacaftor has poor solubility, Vertex developed an amorphous solid dispersion that allows the drug to dissolve more readily during digestion. During prosecution, Vertex relied on evidence that a formulation containing 80% ivacaftor produced unexpectedly favorable solubility results. The ’481 and ’916 patents claim formulations containing exactly 80% ivacaftor, while the ’635 and ’046 patents claim formulations containing “about 80%” ivacaftor. Lupin filed an ANDA seeking approval for a generic ivacaftor product. Lupin’s amorphous solid dispersion contains approximately 74.257% or 74.258% ivacaftor and differs from Vertex’s formulation in both its non-ivacaftor ingredients and its manufacturing process: Vertex uses dry granulation, while Lupin uses wet granulation. Vertex sued and asserted literal infringement of the patents claiming “about 80%” ivacaftor and infringement under the doctrine of equivalents. Vertex conceded that Lupin did not literally infringe the claims requiring exactly 80% ivacaftor. After trial, the court found the asserted claim not infringed.
Why Lupin Prevailed: The court had previously construed “about” according to its plain and ordinary meaning to a person of ordinary skill in the art, making the central question whether approximately 74.26% ivacaftor could reasonably be considered “about 80%.” Vertex’s expert characterized “about 80%” as referring more generally to a “high drug load” and opined that the term encompassed at least 70% to 90% ivacaftor. The court rejected that testimony as lacking a scientific or principled basis and expressly found Vertex’s expert less credible than Lupin’s expert. Lupin’s expert instead interpreted “about” to mean “nearly the same as,” with a permissible variance of less than a couple of percentage points. The court credited that interpretation, finding it consistent with the prosecution history, including the examiner’s treatment of 79.9% as an example of “about 80%.” Because Lupin’s approximately 74.26% formulation differed from 80% by substantially more than a couple of percentage points, the court found no literal infringement.
The court likewise rejected Vertex’s attempt to expand its claims through the doctrine of equivalents. The precise numerical limitations in the claims and the prosecution history both weighed heavily against extending the claims to Lupin’s formulation. Vertex had obtained its patents by emphasizing the unexpected results achieved at 80% ivacaftor, while its effort to obtain claims covering the broader 72%-to-88% range had been rejected. Permitting Vertex to treat approximately 74% as equivalent to 80% or “about 80%” would therefore effectively erase the numerical limitation that distinguished the patented invention and risk ensnaring Vertex’s own prior art.
The court also found that Vertex failed to establish equivalence under either the function-way-result or insubstantial-differences test. Vertex principally relied on the bioequivalence of the products, arguing that both used amorphous dispersions of ivacaftor to treat cystic fibrosis. But the court explained that bioequivalence does not establish patent infringement; otherwise, virtually any generic version of a patented drug would infringe. Nor did the insubstantial-differences test support Vertex. The intrinsic evidence did not show that a POSA would regard approximately 74.26% and 80% ivacaftor as equivalent drug loads, and the products were manufactured through materially different wet- and dry-granulation processes.
