PTAB challenges

Proceedings overview

U.S. Patent 12,168,036 is currently involved in two Post-Grant Review (PGR) proceedings before the Patent Trial and Appeal Board (PTAB). One PGR (PGR2025-00085) has been instituted, challenging all 38 claims of the patent, while a second PGR (PGR2026-00039) is pending and seeks joinder with the instituted proceeding. This situation indicates an active challenge to the patent's validity, placing the patent owner in a defensive posture and offering potential avenues for a defendant to challenge the patent.

PGR2025-00085 — Alvotech USA Inc. et al. v. Regeneron Pharmaceuticals, Inc.

• Type: Post-Grant Review
• Filed: 2025-09-17
• Status: Trial Instituted (Instituted in March 2026, without an opinion).
• Judge panel: Not publicly available in the provided search results.
• Petition grounds: Alvotech challenged claims 1-38 of U.S. Patent 12,168,036. The grounds for unpatentability include lack of novelty, obviousness (under 35 U.S.C. § 103), and lack of written description (under 35 U.S.C. § 112). Specifically, Alvotech argues that Regeneron had previously disclosed high-concentration aflibercept formulations (100 mg/ml and higher) with high doses (up to 10 mg) and that the '036 patent did not solve a novel viscosity problem. The obviousness arguments are based on multiple combinations of prior art, including Regeneron's own patents and publications.
• Institution decision: Instituted in March 2026. The PTAB granted institution without issuing a detailed opinion at the time.
• Final Written Decision: Not yet issued. The trial year commenced in March 2026, so a Final Written Decision would typically be due by March 2027.
• Settlement / termination: No public information indicates a settlement or termination of this specific PGR proceeding.
• Appeal: Not applicable yet, as no Final Written Decision has been issued.
• Defensive value: The institution of this PGR means that all 38 claims of the patent are currently under review for patentability, including independent claims 1, 16, 21, 28, and 33. A defendant facing assertion of this patent can monitor this proceeding for potential invalidation of claims, which could significantly weaken the patent owner's position. The breadth of claims challenged (all 38) indicates a comprehensive attack on the patent's validity.

PGR2026-00039 — Biocon Biologics Limited et al. v. Regeneron Pharmaceuticals, Inc.

• Type: Post-Grant Review
• Filed: 2026-04-02
• Status: Pending. The petition seeks joinder with the previously instituted PGR2025-00085.
• Judge panel: Not publicly available in the provided search results.
• Petition grounds: Biocon challenged claims 1-38 of U.S. Patent 12,168,036. The grounds for unpatentability include obviousness and lack of written description under 35 U.S.C. § 112. Biocon's petition is substantively identical to Alvotech's petition in PGR2025-00085.
• Institution decision: A decision on institution for this specific petition, including the request for joinder, is pending.
• Final Written Decision: Not yet issued.
• Settlement / termination: No public information indicates a settlement or termination of this specific PGR proceeding. Note that Biocon and Regeneron previously settled litigation concerning a different aflibercept patent (U.S. Patent No. 11,084,865), allowing Biocon to launch its biosimilar Yesafili in the US in the second half of 2026. This settlement did not pertain to US12168036.
• Appeal: Not applicable yet.
• Defensive value: As a pending PGR seeking joinder with an instituted proceeding, this case represents a reinforcing challenge to the patent. If joinder is granted or the petition is independently instituted, it demonstrates multiple parties view the patent as vulnerable. This increases the pressure on the patent owner and provides a defendant with additional insight into the art and arguments being leveraged against the patent.

Strategic summary

Both PGR2025-00085 and PGR2026-00039 are actively challenging all claims (1-38) of U.S. Patent 12,168,036. PGR2025-00085, filed by Alvotech, has already been instituted on grounds of novelty, obviousness, and written description, meaning the PTAB found a reasonable likelihood that at least one challenged claim is unpatentable. PGR2026-00039, filed by Biocon, is substantively identical and is seeking joinder. As of the current date (2026-05-29), no claims have been canceled or sustained, and no Final Written Decisions have been issued for either proceeding.

The estoppel landscape under 35 U.S.C. § 315(e)(2) will be significant. If PGR2025-00085 proceeds to a Final Written Decision, Alvotech (and potentially Biocon if joinder is granted) will be estopped from raising in subsequent district court litigation or other PTAB proceedings any ground that they raised or reasonably could have raised during the PGR. For a defendant currently being asserted against, the ongoing PGRs mean that the patent is under a substantial cloud of uncertainty. The arguments put forth by Alvotech and Biocon, particularly concerning prior art disclosures of high-concentration aflibercept formulations and the purported lack of a viscosity problem solved by the patent, provide a strong foundation for a third party to evaluate potential invalidity contentions.

There are pattern signals of multiple biosimilar developers (Alvotech and Biocon) challenging the same patent, indicating a coordinated or at least parallel effort against Regeneron's high-dose aflibercept product, Eylea HD®. This suggests the patent is perceived as a significant barrier to market entry for biosimilars. There is no information in the provided search results to indicate that the patent owner has pursued PTAB appeals aggressively for this specific patent or that a defensive aggregator is involved.

Recommended next steps

• Monitor PGR2025-00085 closely: The institution decision has already been rendered in March 2026, without an opinion, meaning the trial is underway. The statutory deadline for the Final Written Decision in PGR2025-00085 is generally one year from the institution date, placing it around March 2027. Review the docket for all filings, especially expert reports, cross-examinations, and pre-hearing briefs, to understand the specific arguments and evidence being presented. Accessing the institution decision document, if it becomes publicly available with reasoning, would be highly beneficial.
• Monitor PGR2026-00039: Keep track of the PTAB's decision on Biocon's request for joinder with PGR2025-00085. A decision on institution for this petition is pending. If joinder is granted, the two cases will likely proceed on a similar timeline, with shared evidence and arguments.
• Assess validity arguments: Given that all 38 claims are challenged on grounds of novelty, obviousness, and written description, thoroughly evaluate the prior art cited by Alvotech and Biocon against your own products or activities. The arguments that Regeneron had previously disclosed high-concentration formulations and that no "viscosity problem" was solved (as asserted by Alvotech) are critical points.
• Consider a parallel PGR (if applicable): If your company has a strong, unique prior art position not already presented, or if the current PGRs face unexpected challenges, filing your own PGR could be an option, though the nine-month window from patent grant for filing PGRs has passed for this patent (granted 2024-12-17, so the deadline was 2025-09-17). However, joining an existing PGR could be an option if your interests align and the PTAB permits.
• Prepare for potential Federal Circuit appeal: If a Final Written Decision is issued, be prepared for either party to appeal to the Federal Circuit, which would extend the timeline for a definitive resolution on patent validity.