DCT

1:19-cv-01732

Cabaret Biotech Ltd v. Kite Pharma Inc

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Key Events
Amended Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:19-cv-01732, D. Del., 10/21/2019
  • Venue Allegations: Venue is alleged to be proper as Defendants are Delaware corporations that have conducted substantial and continuing business in the district.
  • Core Dispute: Plaintiff, the patent owner and licensor, seeks a declaratory judgment that its patent is not invalid, following threats from Defendant, the licensee, to challenge the patent's validity and cease royalty payments for its cancer therapy product.
  • Technical Context: The lawsuit concerns Chimeric Antigen Receptor T-cell (CAR-T) technology, a form of cancer immunotherapy where a patient's own immune cells are genetically engineered to recognize and attack cancer cells.
  • Key Procedural History: The parties have an exclusive license agreement dating to 2013, under which Defendants have paid royalties on their product YESCARTA®. The complaint alleges that Defendants previously touted the patent-in-suit as protecting YESCARTA®, sought to extend its term, and defended it in reexamination proceedings, but have now threatened to sue for a declaration of invalidity. The patent-in-suit previously survived two ex parte reexaminations. Plaintiff's original complaint included a count for a declaratory judgment of infringement, which was omitted from the current amended complaint in reliance on Defendants' representation that they would not contest infringement if the patent is found valid.

Case Timeline

Date Event
1992-03-18 Earliest Priority Date for ’465 Patent
2010-06-22 ’465 Patent Issued
2012-12-00 Kite submits first module of Biologics License Application for BLA
2013-12-12 License Agreement executed between Cabaret and Kite
2014-12-00 Kite submits Investigational New Drug (IND) application to FDA
2017-03-00 Kite submits final module for BLA
2017-08-29 USPTO issues reexamination certificate for ’465 Patent
2017-10-18 YESCARTA® (KTE-C19) approved by FDA
2018-10-00 Defendants allegedly begin protesting royalty payment obligations
2019-08-20 Gilead allegedly threatens lawsuit for declaratory judgment
2019-10-21 Amended Complaint for Declaratory Judgment filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 7,741,465 - "Chimeric Receptor Genes and Cells Transformed Therewith"

Issued June 22, 2010 (as amended by Reexamination Certificate C1, issued August 29, 2017)

The Invention Explained

  • Problem Addressed: The patent describes challenges in cancer immunotherapy, noting that while T-cells are potent killers, their natural recognition is limited, and while antibodies can target many antigens, they have difficulty penetrating solid tumors and recruiting an effective immune response ('465 Patent, col. 1:16-21; col. 2:54-62).
  • The Patented Solution: The invention is a chimeric receptor gene that combines the targeting specificity of an antibody with the cell-killing machinery of a lymphocyte, like a T-cell ('465 Patent, Abstract). It achieves this by genetically fusing a single-chain Fv (scFv) domain from an antibody to the signaling domains of a lymphocyte-activating receptor. When this chimeric gene is inserted into a lymphocyte, the cell is "re-programmed" to recognize the antibody's target and initiate an immune attack, bypassing the body's normal antigen presentation pathways ('465 Patent, col. 4:26-40).
  • Technical Importance: This approach creates "designer lymphocytes" that can be directed against virtually any target for which an antibody exists, a concept the complaint describes as "seminal" in the field of cancer immunotherapy (Compl. ¶12).

Key Claims at a Glance

  • The complaint seeks a declaration that "the claims" of the ’465 Patent are not invalid, without identifying specific claims (Compl. ¶56). Following reexamination, the patent includes independent claims 21 and 30.
  • Independent Claim 21 recites a chimeric DNA comprising:
    • a first DNA segment encoding a single-chain Fv domain (scFv) of a specific antibody; and
    • a second DNA segment encoding the transmembrane and cytoplasmic domains of an endogenous protein expressed on lymphocytes that triggers their activation;
    • wherein the endogenous protein is CD28; and
    • which, upon transfection into lymphocytes, expresses a single, continuous chain that gives the lymphocyte MHC non-restricted, antibody-type specificity.
  • Independent Claim 30 is similar but recites that the endogenous protein is CD8.

III. The Accused Instrumentality

Product Identification

YESCARTA® (axicabtagene ciloleucel) (Compl. ¶1).

Functionality and Market Context

  • YESCARTA® is described as a "CD19-directed genetically modified autologous T cell immunotherapy" (Compl. ¶31). The therapy involves taking a patient's own T-cells and genetically engineering them to express a chimeric antigen receptor that targets the CD19 antigen, which is present on certain leukemia and lymphoma cells (Compl. ¶29).
  • The complaint alleges that YESCARTA® embodies the invention of the ’465 Patent and that Defendants have paid royalties under a license to the patent for its sales (Compl. ¶1, ¶14). The product is commercially significant, as evidenced by Gilead's acquisition of Kite for $11.9 billion in 2017 (Compl. ¶32).

IV. Analysis of Infringement Allegations

The complaint is for a declaratory judgment of non-invalidity and does not contain detailed infringement allegations or a claim chart. Plaintiff states it omitted a count for declaratory judgment of infringement in reliance on Defendants' representation that they "will not contest infringement apart from validity" (Compl. ¶2). The complaint asserts more generally that "YESCARTA® embodies the invention disclosed in the ’465 Patent" (Compl. ¶14) and that Defendants have previously made representations to the USPTO and SEC that the patent protects the product (Compl. ¶17, ¶37).

The implied infringement theory is that YESCARTA®, as a CAR-T therapy, practices the fundamental invention claimed in the ’465 Patent. Specifically, the YESCARTA® construct is widely understood in the field to utilize an scFv that targets the CD19 antigen, fused to intracellular signaling domains that include the CD28 co-stimulatory domain. This structure corresponds to the elements recited in the reexamined independent claim 21 of the ’465 Patent. The dispute, as framed by the complaint, is therefore not over whether YESCARTA® practices the claims, but whether those claims are valid.

No probative visual evidence provided in complaint.

V. Key Claim Terms for Construction

  • The Term: "a second DNA segment encoding partially or entirely the transmembrane and cytoplasmic...domains of an endogenous protein, wherein said endogenous protein is CD28" (from Claim 21).
  • Context and Importance: The identity of the signaling domain is critical to a CAR-T product's efficacy and safety profile. CD28 provides a key co-stimulatory signal required for robust T-cell activation. The validity of claim 21 will likely depend on whether combining an scFv with the specific CD28 signaling domains was a non-obvious advance over prior art that may have disclosed other signaling components. Practitioners may focus on this term because the patentability of the claimed invention, as distinguished from the prior art, could turn on the specific selection of CD28.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: A party arguing that the selection of CD28 was obvious might point to the specification’s disclosure of CD28 as one of several "lymphocyte accessory and adhesion molecules" that "can also be used in accordance with the present invention" ('465 Patent, col. 10:49-53). This could suggest CD28 was merely one option from a known and finite list of candidates for providing a co-stimulatory signal.
    • Evidence for a Narrower Interpretation: A party defending the claim's validity may argue that the specification distinguishes CD28 by teaching its role in transducing a "co-stimulatory signal for T-cell activation" ('465 Patent, col. 10:50-52). The fact that the USPTO allowed a claim specifically limited to CD28 during reexamination may suggest that patentable weight was given to the specific properties and advantages of using this particular molecule over other potential signaling domains.

VI. Other Allegations

The complaint does not allege infringement and therefore makes no specific allegations of indirect or willful infringement. However, the complaint does request a finding that the case is "exceptional" under 35 U.S.C. § 285, which would entitle Plaintiff to attorneys' fees (Compl., Prayer for Relief (b)). The basis for this request is Defendants' alleged "precipitous about-face" regarding the patent's validity (Compl. ¶16). The complaint highlights Defendants' prior conduct, including licensing the patent, paying royalties, publicly touting the patent's role in protecting YESCARTA®, and authorizing Plaintiff to seek a patent term extension based on the product, as being inconsistent with their current threat to challenge its validity (Compl. ¶¶ 17-20, 33-34).

VII. Analyst’s Conclusion: Key Questions for the Case

  • A central substantive question will be one of validity: at the time of the invention, would it have been obvious to a person of ordinary skill in the art to create a chimeric antigen receptor by combining a single-chain Fv (scFv) antibody fragment with the specific transmembrane and cytoplasmic signaling domains of the CD28 co-stimulatory molecule?
  • A key procedural and equitable question will be one of licensee estoppel: to what extent are Defendants barred from challenging the ’465 Patent’s validity, given their alleged prior conduct of licensing the patent, paying royalties for YESCARTA®, and making representations to the public and the USPTO that the patent protected the product?