Our Patent Case Summaries provide a weekly summary of the precedential patent-related opinions issued by the Court of Appeals for the Federal Circuit and the opinions designated precedential or informative by the Patent Trial and Appeal Board.
Exelixis, Inc. v. MSN Laboratories Private Ltd., et al.
No. 2025-1236 (Fed. Cir. (D. Del.) Aug. 31, 2026). Opinion by Stoll, joined by Moore and Moore (sitting by designation).
Exelixis holds the New Drug Application for Cabometyx®, a tablet containing cabozantinib (L)-malate, which is indicated to treat kidney, liver, and differentiated thyroid cancer. Exelixis obtained three patents (the Malate Salt Patents) and later obtained a fourth patent (the ’349 patent).
After MSN submitted an Abbreviated New Drug Application for generic cabozantinib (L)-malate tablets, Exelixis sued for infringement. MSN conceded infringement for the Malate Salt Patents but argued that the claims were invalid for lack of written description under 35 U.S.C. § 112. For the ’349 patent, MSN contested both infringement and validity.
After a bench trial, the district court held the Malate Salt Patents infringed and not invalid and the ’349 patent not infringed and not invalid. MSN appealed challenging the district court’s findings that the claims of the Malate Salt Patents and the ’349 patent are not invalid.
Exelixis initially cross-appealed to challenge the noninfringement finding for the ’349 patent, but dismissed it, thus rendering the noninfringement judgment final. MSN nonetheless continued to maintain its appeal challenging the district court’s validity decision for the ’349 patent. MSN also moved to dismiss its appeal as moot and to vacate the underlying decision on the ’349 patent.
The Federal Circuit affirmed-in-part and dismissed-and-vacated-in-part. To begin, the court affirmed the district court’s written-description ruling for the Malate Salt Patents. The court explained that “a sufficient written description for disclosure of a claimed genus requires the disclosure of either a representative number of species falling within the scope of the genus or structural features common to the members of the genus so that one of skill in the art can visualize or recognize the members of the genus.” Here, there was “no clear error in the district court’s finding that disclosing the chemical name and formula of cabozantinib (L)-malate salt, as well as that the structure of the salt is crystalline, is an identification of the structural features possessed by members of the genus.” Also, the claims were “no broader than the written description,” and the specification disclosed processes used to make the invention.
As to the ’349 patent, the Federal Circuit agreed with MSN that this portion of its appeal was moot. The court explained that under Cardinal Chemical, if “either party has advised the court of a material change in circumstances that entirely terminated the party’s controversy, it would be proper either to dismiss the appeal or to vacate the entire judgment of the District Court,” which was “the situation here.” The Federal Circuit ruled that “Exelixis’s unilateral decision to drop its cross-appeal frustrated MSN’s attempt to seek review” of the district court’s ruling that MSN failed to prove invalidity of the ’349 patent. “The appropriate resolution,” the Federal Circuit held, “is vacatur of the district court’s judgment” on that patent.
Netlist, Inc. v. Micron Technology, Inc., et al.
No. 2024-1707 (Fed. Cir. (PTAB) Sept. 2, 2026). Opinion by Reyna, joined by Linn and Stark.
Netlist owns a patent directed to computer memory systems designed to improve the performance and capacity of memory modules. Samsung petitioned for IPR challenging the claims as obvious over the combination of two prior art references, “Ellsberry” and “Halbert.” Micron later filed a petition on the same ground and joined the proceeding. The Patent Trial and Appeal Board instituted review and determined that all challenged claims were obvious over the two references. Netlist appealed.
Netlist made two primary arguments on appeal. First, it argued that “the Board erred by finding that Ellsberry teaches data paths that are enabled at the required time using a latency parameter,” as required by a claim limitation. Netlist contended that the Board’s finding that Ellsberry teaches buffers that use a latency parameter to control timing of enabling the buffer data paths “was based on unsubstantiated speculation about Ellsberry’s operation.” But the Federal Circuit disagreed because “the Board’s finding was supported by substantial evidence,” including expert testimony and Ellsberry’s teachings.
Netlist also argued that the Board erred by using another Netlist patent—one that was not part of the ground presented in the petition—to supply the limitation of enabling the data paths at the required time. The Federal Circuit acknowledged that the petition did not assert this other patent in the petition ground and that the Board relied on the patent’s teaching. The court held, however, that “any potential error was harmless because the Board alternatively found that Ellsberry alone” taught the limitation.
Second, Netlist argued that the Board erred by determining that Ellsberry teaches “enabling a data path,” as recited by two claim limitations. The Federal Circuit disagreed and held that Ellsberry’s Figure 2 and paragraph 31 constitute substantial evidence that Ellsberry teaches the requirement. The court made similar determinations for other challenges raised by Netlist.
Lastly, the Federal Circuit rejected Netlist’s general challenge under the Administrative Procedure Act (APA) as inadequately developed. Netlist separately asserted that the Board failed to address its arguments for certain dependent claims in violation of the Board’s APA obligations. But the Federal Circuit disagreed, ruling that the Board’s Final Written Decision “directly addressed both of Netlist’s arguments” for the dependent claims. The Federal Circuit was able to “discern the Board’s path to reaching its conclusion for these claims,” and thus concluded “there is no APA violation.”