Patent 8273735

PTAB challenges

AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.

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Proceedings on file (0)

All PTAB activity →

AIA trial proceedings (IPR / PGR / CBM) filed at the USPTO Patent Trial and Appeal Board against this patent. Sourced from the USPTO Open Data Portal and refreshed every six hours; each proceeding number deep-links to the PTAB E2E docket.

No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.

PTAB challenges

AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.

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Proceedings overview

The USPTO Open Data Portal API currently reports no AIA trial proceedings (Inter Partes Review, Post-Grant Review, or Covered Business Method) on file for US Patent 8,273,735. Despite active litigation, including a Federal Circuit decision affirming a district court's finding of obviousness for asserted claims, there is no public record of a corresponding AIA trial at the PTAB.

Strategic summary

Based on the available information, there are no PTAB proceedings (IPR, PGR, or CBM) on record for US Patent 8,273,735. This means that, unlike cases where claims might be canceled or sustained by the PTAB, the claims of US8273735 have not been directly challenged or affirmed through these specific administrative trial processes.

The litigation summary indicates that the asserted method claims of US8273735 were found invalid as obvious over Kondo's 1999 paper by a district court, and this judgment was affirmed by the Federal Circuit in Otsuka Pharmaceutical Co. v. Lupin Ltd. (Case No. 24-2297). This invalidation, however, stems from district court proceedings rather than a PTAB Final Written Decision. As such, the specific claims invalidated by the district court are effectively canceled for the parties involved in that litigation, but the PTAB itself has not rendered a decision on the patentability of any claims.

The absence of PTAB activity means there is no estoppel under 35 U.S.C. § 315(e)(2) for potential petitioners, as no IPR has gone to a final written decision. Therefore, a defendant facing assertion of this patent could still pursue an IPR on any grounds of patentability (e.g., §§ 102, 103) based on prior art, including Kondo's 1999 paper if applicable, without being barred by prior PTAB decisions.

The lack of PTAB challenges for a patent involved in significant ANDA litigation could indicate several factors:

  • The prior art landscape might have been complex, leading litigants to prioritize district court defenses.
  • Strategic decisions by potential petitioners to avoid PTAB.
  • The claims of US8273735 might have been structured in a way that made them less amenable to a straightforward IPR challenge, or the best prior art was already being leveraged in district court.

Recommended next steps

Given the absence of PTAB activity for US Patent 8,273,735:

  • For a defendant currently being asserted against: The district court's finding that asserted method claims of US8273735 are invalid as obvious (affirmed by the Federal Circuit) provides a strong defense against those specific claims, particularly for processes that fall outside the claimed molar equivalent range. It is crucial to obtain and review the full district court opinion from Otsuka Pharmaceutical Co., Ltd. v. Lupin Limited (Delaware District Court, Case No. 1:21-cv-00900-RGA) and the Federal Circuit affirmance (Case No. 24-2297). This provides a direct legal precedent for invalidity on specific claims.
  • Consideration for new PTAB petitions: The absence of prior IPRs means there's no PTAB-imposed estoppel. If a defendant has new prior art or new arguments based on existing art not fully litigated in the district court context, filing a new IPR petition remains an option. However, careful consideration should be given to the prior district court's obviousness findings and whether a PTAB petition would offer a distinct advantage or risk inconsistent rulings.
  • Monitoring: Continue to monitor the USPTO PTAB E2E system and public dockets for any future filings against US8273735, especially given its active litigation status and impending expiration in 2028.

It is important to reiterate that while the district court found claims invalid, this judgment pertains to the parties and scope of that particular litigation. The patent itself has not been subjected to a PTAB trial.

External Resources Cited:

The USPTO Open Data Portal API currently reports no AIA trial proceedings (Inter Partes Review, Post-Grant Review, or Covered Business Method) on file for US Patent 8,273,735. Despite active litigation that led to a Federal Circuit decision affirming a district court's finding of obviousness for asserted claims, there is no public record of a corresponding AIA trial at the PTAB.

Strategic summary

Based on the available information, there are no PTAB proceedings (IPR, PGR, or CBM) on record for US Patent 8,273,735. This means that, unlike cases where claims might be canceled or sustained by the PTAB, the claims of US8273735 have not been directly challenged or affirmed through these specific administrative trial processes.

The litigation summary indicates that the asserted method claims of US8273735 were found invalid as obvious over Kondo's 1999 paper by a district court, and this judgment was affirmed by the Federal Circuit in Otsuka Pharmaceutical Co. v. Lupin Ltd. (Case No. 24-2297). This invalidation, however, stems from district court proceedings rather than a PTAB Final Written Decision. As such, the specific claims invalidated by the district court are effectively canceled for the parties involved in that litigation, but the PTAB itself has not rendered a decision on the patentability of any claims.

The absence of PTAB activity means there is no estoppel under 35 U.S.C. § 315(e)(2) for potential petitioners, as no IPR has gone to a final written decision. Therefore, a defendant facing assertion of this patent could still pursue an IPR on any grounds of patentability (e.g., §§ 102, 103) based on prior art, including Kondo's 1999 paper if applicable, without being barred by prior PTAB decisions.

The lack of PTAB challenges for a patent involved in significant ANDA litigation could indicate several factors:

  • The prior art landscape might have been complex, leading litigants to prioritize district court defenses.
  • Strategic decisions by potential petitioners to avoid PTAB.
  • The claims of US8273735 might have been structured in a way that made them less amenable to a straightforward IPR challenge, or the best prior art was already being leveraged in district court.

Recommended next steps

Given the absence of PTAB activity for US Patent 8,273,735:

  • For a defendant currently being asserted against: The district court's finding that asserted method claims of US8273735 are invalid as obvious (affirmed by the Federal Circuit) provides a strong defense against those specific claims, particularly for processes that fall outside the claimed molar equivalent range. It is crucial to obtain and review the full district court opinion from Otsuka Pharmaceutical Co., Ltd. v. Lupin Limited (Delaware District Court, Case No. 1:21-cv-00900-RGA) and the Federal Circuit affirmance (Case No. 24-2297). This provides a direct legal precedent for invalidity on specific claims.
  • Consideration for new PTAB petitions: The absence of prior IPRs means there's no PTAB-imposed estoppel. If a defendant has new prior art or new arguments based on existing art not fully litigated in the district court context, filing a new IPR petition remains an option. However, careful consideration should be given to the prior district court's obviousness findings and whether a PTAB petition would offer a distinct advantage or risk inconsistent rulings.
  • Monitoring: Continue to monitor the USPTO PTAB E2E system and public dockets for any future filings against US8273735, especially given its active litigation status and impending expiration in 2028.

It is important to reiterate that while the district court found claims invalid, this judgment pertains to the parties and scope of that particular litigation. The patent itself has not been subjected to a PTAB trial.

Generated 5/22/2026, 12:02:14 AM