Patent 11358953
Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
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No PTAB proceedings on file. This patent has not been challenged through Inter Partes Review, Post-Grant Review, or Covered Business Method review at the USPTO. The absence is itself a signal — well-asserted patents eventually attract IPRs.
Cases on file (0)
Specific litigation cases in our database that name US patent 11358953. The free-form analysis below may also discuss cases beyond this list.
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Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
Known Litigation Involving US Patent 11358953:
As of April 26, 2026, the following litigation is known for US Patent 11358953:
1. Enanta Pharmaceuticals, Inc. v. Pfizer Inc.
- Plaintiff(s): Enanta Pharmaceuticals, Inc.
- Defendant(s): Pfizer Inc.
- Jurisdiction: U.S. Court of Appeals for the Federal Circuit (CAFC)
- Case Number: Not explicitly provided in the initial summary, but typically a CAFC appeal case number would be available. The prior summary mentions "CAFC 2026 Dockets / Current Legal Status" and refers to a "lower court's decision," suggesting an appeal.
- Filing Date: Not explicitly provided for the CAFC case, but the prior summary states the patent's filing date was November 9, 2021.
- Outcome/Current Status: The CAFC has affirmed a lower court's decision, ruling that all claims of US Patent 11,358,953 are invalid. This outcome was based on the finding that the patent could not claim priority from its earlier provisional application due to inadequate written description support for a C1-alkyl group, leading to anticipation by Pfizer's prior public disclosure of nirmatrelvir in April 2021.
2. Massachusetts District Court Case
- Plaintiff(s): Enanta Pharmaceuticals Inc.
- Defendant(s): Not specified in the provided information, but likely Pfizer Inc. given the context of the CAFC case.
- Jurisdiction: Massachusetts District Court
- Case Number: 1:22-cv-10967
- Filing Date: The related "Application filed by Enanta Pharmaceuticals Inc" and "Priority to US17/522,176" occurred on 2021-11-09. The provided litigation data indicates a US case filed in Massachusetts District Court, with the case number 1:22-cv-10967. This implies the filing date would be in 2022.
- Outcome/Current Status: The outcome of this specific District Court case is that it was appealed to the CAFC, which subsequently ruled the patent claims invalid.
3. Court of Appeals for the Federal Circuit Case
- Plaintiff(s): Not specified (likely Enanta Pharmaceuticals Inc. as appellant)
- Defendant(s): Not specified (likely Pfizer Inc. as appellee)
- Jurisdiction: Court of Appeals for the Federal Circuit
- Case Number: 25-1427
- Filing Date: Not explicitly stated, but the case number "25-1427" suggests a filing in 2025.
- Outcome/Current Status: The CAFC has ruled that all claims of US11358953 are invalid.
Generated 6/24/2026, 12:02:33 AM