On May 16, 2025, the Court in Case No. 1:21-cv-01478 (D. Del.) granted bluebird bio’s motion for summary judgment, finding that its gene therapy Zynteglo® (betibeglogene autotemcel) does not infringe San Rocco Therapeutics‘ exclusively licensed U.S. Patent Nos. 7,541,179 and 8,058,061, which claim recombinant vectors that are used in the treatment of hemoglobinpathies, such as Sickle Cell Disease and Beta Thalassemia.
In April 2024, the PTAB issued Final Written Decisions in IPR2023-00070 and IPR2023-00074 filed by Sarepta against the patents asserted in this litigation, finding none of the challenged claims unpatentable as anticipated or obvious (previously reported PTAB Issues Final Written Decisions On Zynteglo® Gene Therapy Patents). CAFC appeals 24-2010 and 24-2016 are pending.
In June 2024, the Court issued a claim construction opinion, and in light of the constructions, Plaintiff conceded that it could not prove literal infringement of four claim elements in every asserted claim. Instead, Plaintiff relied on the doctrine of equivalents. Defendants argued that the Plaintiff was barred from asserting the equivalency arguments because of prosecution history estoppel.
The Court agreed with Defendants that Plaintiff was estopped from its doctrine of equivalents arguments. During prosecution, Plaintiff had amended the claim language “large portions of the B-globin locus control region” to “a 3.2-kb nucleotide fragment” to overcome an indefiniteness rejection. The Court found that Defendants BB305 nucleotide, which is 2.7 kb long, does fall under the original “large portions” claim language, but is not covered by the narrowed, specific “3.2 kb” language allowed after the amendment. Therefore, BB305 is within the area of the disclaimed subject matter, and amendment-based prosecution history estoppel applies. The Court also found that the “tangential relation” exception to prosecution history estoppel did not apply based on comments made by Plaintiff during prosecution that showed the amendment was made to claim one specific fragment length, 3.2 kb.
The Court further found Plaintiff was barred by argument-based estoppel given at least 20 statements during prosecution that made clear the claimed nucleotide fragment is 3.2 kb.
In 2024, bluebird bio reported $62.3 million in revenue for Zynteglo®.
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The author would like to thank April Breyer Menon for her contributions to this article.
