US 6555554

I'll search for authoritative information on this specific patent number.

Let me check the litigation history and any 2026 Federal Circuit activity specifically.

Let me look specifically for Federal Circuit 2026 activity and the litigation record.

US Patent 6,555,554 — verified summary

Identification (interpreted literally as US 6,555,554 B2)

Note a minor data inconsistency: Google Patents displays "prior art date 1996-07-24" alongside a priority claim from US 08/701,494 dated 1996-08-22; I am reporting both rather than resolving them.

Abstract (as published). "Substituted 1-oxo-2-(2,6-dioxopiperidin-3-yl)isoindolines are useful in reducing undesirable levels of TNFα in a mammal. Typical embodiments are pharmaceutical compositions containing 1-oxo-2-(2,6-dioxopiperidin-3-yl)-4-aminoisoindoline and 1-oxo-2-(2,6-dioxo-3-methylpiperidin-3-yl)-4-aminoisoindoline." (The first of those compounds is lenalidomide.)

Independent claims (17 claims total; 2 independent)

• Claim 1 — pharmaceutical composition. A composition comprising, in combination with a pharmaceutically and physiologically suitable carrier, a compound of the depicted formula. In plain terms: a medicine containing a 1‑oxo‑isoindoline core bearing the 2,6‑dioxopiperidin‑3‑yl (glutarimide) group at N‑2, where the benzo ring may carry halo, C1–4 alkyl or C1–4 alkoxy at positions 4–7 (or instead one position may be an —NHR⁵ amino group, R⁵ = H or C1–8 alkyl), and the glutarimide 3‑position may carry R⁶ = H, C1–8 alkyl, benzyl, or halo, subject to the stated proviso for the dioxo/fluoro/amino combinations — together with a carrier.

  • Dependents: 2 (R‑configuration), 3 (S‑configuration), 4 (1–100 mg of compound), 5 (powder, tablet, or capsule), 6 (injectable composition), 7 (administered with a therapeutic agent), 8 (that agent is a steroid, neoplastic agent, or antibiotic), 9 (depends on 5: 1–100 mg in single/multiple dosage regimen form).

• Claim 10 — method of use. A method of reducing undesirable levels of TNFα in a mammal by administering an effective amount of a compound of the depicted formula (the same genus of 1‑oxo‑2‑(2,6‑dioxopiperidin‑3‑yl)isoindolines).

  • Dependents: 11 (compound of a narrower, specifically drawn formula — the amino-substituted/3-methyl embodiments per the specification and abstract), 12 (oral or parenteral administration), 13 (in combination with a therapeutic agent), 14 (R‑configuration), 15 (S‑configuration), 16 (single or multiple dosage regimen as a composition containing 1–100 mg), 17 (physiologically acceptable non-toxic acid addition salt form).

In short: claim 1 is a composition claim and claim 10 is a TNFα-reduction method claim; the specification frames the invention as substituted 2‑(2,6‑dioxopiperidin‑3‑yl)phthalimides and 2‑(2,6‑dioxopiperidin‑3‑yl)‑1‑oxoisoindolines used to lower TNFα and treat inflammatory, infectious, immunological and oncogenic conditions, with the granted claims directed to the 1‑oxo (isoindoline) genus.

Litigation / CAFC 2026 check

• No 2026 Federal Circuit docket involving patent 6,555,554 was found. My targeted searches surfaced only unrelated 2026 Federal Circuit/federal matters (e.g., REGENXBIO v. Sarepta; a Ninth Circuit Amazon–Perplexity stay; Google's mandamus petition against VirtaMove's patent 7,519,814, which cites Celgene Corp. v. Peter as precedent). The "Celgene" hits in 2026 materials are case-law citations or unrelated party references, not the '554 patent. This is consistent with the patent having expired in 2016, making live 2026 appellate activity on it improbable.
• Family litigation flags. Google Patents' Unified Patents data flags a family litigation entry for New Jersey District Court case 2:10-cv-05197. The '554 patent is also referenced in Celgene-related district-court filings (e.g., a listing of Celgene patents including "6555554 (the '554 Patent)"), and it appears in the cited-reference lists of numerous later Celgene/EPO filings.
• International family. The '554 family includes EP 0925294, with lenalidomide Supplementary Protection Certificates in LU, DK, FR, IE, GB and AT.

Uncertainty / limitations

1. I could not directly query USPTO Patent Center or Patent Public Search; the record above is grounded in the authoritative full patent text you supplied plus Google Patents, Justia, uspto.report, DrugPatentWatch, Unified Patents, and the FDA Orange Book. Fees/status fields at USPTO should be re-verified in Patent Center for any current-legal-status conclusion.
2. The claim-formula images were not machine-readable in the sources; the substituent scope in my plain-language reading of claims 1 and 10 is inferred from the specification's Formula I definition and the abstract. The exact recitation of claim 11 (narrower formula) could not be read verbatim — treat that item as the least certain.
3. No annual-fee, reissue, reexamination, or PTAB (IPR/PGR) record specific to the '554 patent was surfaced; I cannot confirm or exclude such proceedings from the material available.

I'll research litigation involving US patent 6555554 specifically.

Litigation Involving U.S. Patent No. 6,555,554 ("the '554 patent")

Bottom line: I found one principal patent-infringement action in which the '554 patent was actually asserted — Celgene's Revlimid® litigation against Natco Pharma — plus several antitrust/class actions in which the '554 is referenced (as an Orange Book patent) but not asserted as a claim in suit. The '554 patent (assigned to Celgene, expired July 24, 2016, per Orange Book listing) was never the subject of a judgment on the merits that I can verify.

⚠️ Verification note: I relied on Google Patents' litigation link for the patent, DrugPatentWatch's patent-specific litigation page (secondary source), CourtListener/RECAP dockets, and court filings. I could not run an exhaustive PACER docket search, so the list below is limited to what these sources disclose. I did not find any PTAB proceeding (IPR/PGR/CBM) on the '554 itself; the IPR I located (IPR2015-01103) concerns U.S. Pat. No. 6,315,720 (Thalomid), not the '554.

A. Cases in which the '554 patent was asserted (infringement)

Related / consolidated matter: Celgene Corp. v. Natco Pharma Ltd., No. 2:12-cv-04571 (D.N.J., filed July 20, 2012) — asserted the '517, '230, '740, '569, '357 and '219 patents; consolidated with 10-5197 by order of Nov. 9, 2012. I could not confirm from the sources reviewed that the '554 was separately asserted in the 2012 action (it appears to have remained in the consolidated 2010 action).

B. Cases where the '554 is referenced but was not asserted

These are antitrust/consumer actions concerning Celgene's Revlimid (and Thalomid) conduct. The '554 appears because it was an Orange Book–listed Revlimid patent, not because infringement of it was pleaded:

Also reported by DrugPatentWatch as listing the '554 among case patents: Celgene Corp. v. Synthon Pharmaceuticals, Inc., D.N.J. 2:18-cv-10775 (filed June 19, 2018; terminated May 13, 2019 by consent judgment re: Alvogen Pine Brook, LLC). Because the '554 expired July 24, 2016, I regard its appearance in that 2018 case as a portfolio/background reference rather than an asserted patent; I could not confirm the '554 was asserted there.

C. Cautions and open items

• Interpretation of the number is literal: all references above are to U.S. Patent No. 6,555,554 (Google Patents US6555554B2; application 09/781,179). I excluded near-numbers (e.g., '517, '230, '106, '415, '800, '554 appears only as "the '554 patent").
• No merits adjudication of the '554 was located — the District of New Jersey proceedings ended in a stipulation of dismissal (without prejudice) as to that patent, followed by a global consent judgment that did not include it.
• Not verified: whether any other ANDA litigant (e.g., Dr. Reddy's, Mylan, Roxane, Lannett, Barr) ever had the '554 formally asserted against it. Celgene sued Dr. Reddy's three times (2016, 2018, 2019), but the '554 had expired, so I would expect it was not asserted — I could not fully verify this within the sources searched.
• If you need a definitive, exhaustive list, a PACER/Unified Patents docket search keyed to patent number 6,555,554 across all districts (and a PTAB Patent Trial docket check) would be the authoritative next step. https://portal.unifiedpatents.com/litigation/caselist and the patent's Google Patents litigation link (which points to D.N.J. case 2:10-cv-05197) are the starting points.

Would you like me to try to pull the specific ECF filings (Markman Opinion ECF 312, Stipulation ECF 402, Consent Judgment ECF 466) for exact quotes, or attempt a broader district-by-district search?

I'll start by verifying the structured PTAB data and searching for any proceedings on this patent.

Let me search more specifically for proceedings naming the '554 patent.

Let me dig into the Coalition for Affordable Drugs filings against Celgene's Revlimid patents.

PTAB Trial Report — U.S. Patent No. 6,555,554 ("Isoindolines, method of use, and pharmaceutical compositions")

Proceedings overview

Total AIA trial proceedings on file against US6555554: 0 — the canonical USPTO Open Data Portal structured feed for this patent returns no IPR, no PGR, and no CBM, and my independent web sweep (PTAB E2E/PTACTS, Docket Alarm, Big Molecule Watch, DrugPatentWatch) surfaced no petition naming the '554 patent. Breakdown by status is therefore 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denied.

Bottom line defensive posture: this is not an "IPR-hardened" patent and it is not a "claims-canceled" patent — it is an expired patent. US6555554 issued 2003-04-29 and expired 2016-07-24 (Orange Book; it is the '517-family member with the same 1996-07-24 priority date as U.S. 6,281,230, 7,119,106 and 8,288,415). No PTAB challenge was ever mounted against the '554 claims specifically, most plausibly because the patent ran out before a petition was worth filing. If a demand letter cites US6555554 today, the dispositive answer is not "invalidity" — it is "that patent expired nearly a decade ago," and any damages theory is in any event time-barred under 35 U.S.C. § 286's six-year look-back.

Proceedings on US6555554

None

There is no proceeding to report at the patent level. I am stating this affirmatively rather than inferring it: the structured ODP block is the canonical source and says "no AIA trial proceedings for this patent as of the most recent ingest," and no web source contradicts it. I did not invent a proceeding number to fill this section.

Adjacent proceedings on the '517 family (context only — NOT proceedings on '554)

These are portfolio-level events involving sibling patents that share the '554 patent's specification, priority date (1996-07-24), and inventors (George W. Muller, David I. Stirling, Roger Shen-Chu Chen). They are listed here so you understand the litigation climate around the family — none of them adjudicated a claim of US6555554.

IPR2015-01169 — Coalition for Affordable Drugs VI LLC v. Celgene Corporation (SIBLING PATENT — patent number not confirmed as '554)

• Type: Inter Partes Review
• Filed: 2015-05-07 (accorded filing date 2015-05-07)
• Status: Terminated (verbatim from docket metadata)
• Judge panel: Jacqueline Wright Bonilla, Tina Hulse, Toni Scheiner, Grace Karaffa Obermann, Michael Kim, Michael Tierney
• Technology Center: 1600
• Petition grounds: Not verified for this patent. I could not confirm from the sources retrieved which patent number IPR2015-01169 challenged. The docket metadata lists inventors Muller / Stirling / Chen, which is consistent with either the '517 patent or the '554 patent — so do not assume it targeted '554. DrugPatentWatch's lenalidomide tracker places the CFAD VI IPR filed 2015-05-07 against U.S. 5,635,517 (the lead compound patent), which is the better-supported reading.
• Institution decision / FWD: Not verified for this docket. Status is "Terminated," which in PTAB practice means the trial did not reach a Final Written Decision on the merits (settlement, joinder, or adverse judgment).
• Appeal: None indicated.
• Defensive value for '554: Zero directly. Cite it only for family history.

The CFAD wave generally (context)

Kyle Bass's Coalition for Affordable Drugs entities filed a cluster of IPR petitions against Celgene's Revlimid portfolio in 2015, including:

• IPR2015-01103 — Coalition for Affordable Drugs VI LLC v. Celgene, targeting the REMS/distribution patents (Ex. 1047 lists the '554 among the then-current Orange Book patents for Revlimid — i.e., the '554 is cited as background evidence, not as the challenged patent).
• IPR2015-01096 — CFAD v. Celgene (same 2015 period; documents reference the Revlimid Orange Book listing that includes the '554).
• Reported outcomes in that wave included the PTAB invalidating all claims of the '501 patent and 31 claims of the '720 patent as obvious (per a later district-court antitrust complaint, Celgene v. Natco / follow-on antitrust pleadings).

Important caveat: the '554 patent appears in these exhibits only as an Orange Book reference. Its presence in an exhibit list is not evidence of a proceeding against it. I flag this because a careless reader could mistake it for an IPR on the '554.

Strategic summary

Claim status. Because no AIA trial ever reached the '554 claims, the claims were never canceled, never sustained, and never construed by the Board. In PTAB terms they are untested. They are, however, expired as of 2016-07-24, which moots the distinction. Note that the '554's claim scope was narrowed in district court: in Celgene Corp. v. Natco Pharma Ltd. (D.N.J. 2:10-cv-05197), the Markman opinion construed claims of the '230 and '554 patents to be limited to specific stereochemical configurations of lenalidomide, which "solidified noninfringing design-arounds" (Natco's characterization). That construction is historical context; it cannot be asserted against you today because the patent is dead.

Estoppel landscape. There is no § 315(e)(2) estoppel attaching to US6555554 — estoppel is created only by a petitioner's own IPR/PGR that reaches a final written decision, and no such proceeding exists. Practically, estoppel is irrelevant here: you will never be sued on an expired patent, so there is no infringement defense to build and no prior-art ground you need to preserve. If you are being asserted on a different, live Revlimid-family patent (e.g., the later-expiring polymorph or method-of-treatment patents), estoppel from those proceedings — not this one — is what matters, and those are separate patents outside this report's scope.

Pattern signals. CFAD was a hedge-fund-funded challenger, not a defensive aggregator — Unified Patents is not in the chain for the '554 (the Unified Patents link on the Google Patents page points to the district court case 2:10-cv-05197, a litigation-database entry, not a PTAB filing). Celgene did not have to defend the '554 at the Board; it instead managed the '554 through district-court stipulation: on 2015-03-26 the parties filed a stipulation dismissing all claims, counterclaims and affirmative defenses as to the '230, '554, '106 and '415 patents after Natco converted its Paragraph IV certifications to Paragraph III (i.e., Natco agreed to wait for the July 2016 expiry). That is the closest thing to a "resolution" of the '554 anywhere on the record — and it is a court disposition, not a PTAB one.

Recommended next steps

1. If you received a demand citing US6555554: check the date before you spend a dollar on prior art. The patent expired 2016-07-24. There is no enforceable claim. Put the expiry and 35 U.S.C. § 286 in your response letter; if the correspondence demands payment for post-July-2016 conduct, it is baseless on its face.
2. If the real assertion is against a different '517-family patent, do not rely on this report — get the FWDs for the patent actually asserted. The '554's clean PTAB record gives you no leverage; the '501 and '720 REMS patents were invalidated in CFAD IPRs, which may be useful if those specific patents are asserted. Source: PTAB E2E / PTACTS at https://ptacts.uspto.gov/ptacts/ and the CFAD docket pages cited above.
3. Verify the docket yourself before filing anything citing IPR2015-01169. I could not confirm which patent number that docket challenged; the metadata is consistent with the '517 patent. Do not represent to a court that the '554 was challenged in IPR2015-01169 without confirming the patent number on PTAB E2E first — that would be a sanctionable misstatement.
4. No trial-stage deadlines to track. With zero open proceedings, there is no institution deadline, no oral hearing, and no statutory one-year FWD due date to calendar.
5. Treat the absence of PTAB activity as informative, not as weakness. Well-asserted, long-lived patents attract IPRs. The '554 never got one — but the reason is expiry, not invincibility. Do not carry that inference over to the Revlimid patents that remain live.

Verification note: the "PTAB proceedings on file" structured block (USPTO ODP) is treated as canonical and reports zero proceedings. Adjacent-family facts above are sourced from Google Patents (full text, https://patents.google.com/patent/US6555554/en), Docket Alarm (IPR2015-01169), Big Molecule Watch (IPR2015-01103 petition documents), DrugPatentWatch's lenalidomide PTAB tracker, and CourtListener (D.N.J. 2:10-cv-05197, Dkt. 402). Where a source did not confirm a fact — in particular the patent number underlying IPR2015-01169 — I have said so rather than filling the gap.

Ownership & Assignment Analysis — US 6,555,554 B2

Data-access caveat (read first): My tooling in this session could retrieve the Google Patents front-page/legal-events data, Orange Book listings, and the D.N.J. litigation docket, but it could not return any record from USPTO Assignment Center / the Patent Assignment Search API. Consequently I have no reel/frame numbers, execution dates, correspondents, or assignee names from recorded assignment documents. I will not invent them. Where the section below says "no recorded assignment retrieved," that reflects my access limit, not a confirmed absence in the USPTO database. The reel/frame fields are left explicitly blank rather than filled with placeholders.

Inventors

Pattern notes: All three are career Celgene personnel, not founders of a startup that later shed the portfolio. There is no observable "all inventors out within 12 months" pattern; the assignment is a routine employee-invention assignment to the corporate employer, and the inventors continued in Celgene's employ as the lenalidomide program advanced to NDA 021880 (REVLIMID, approved 2005-12-27).

The application is a continuation-family member, traced on the face of the record to:

• US 08/701,494 (priority 1996-08-22) → US 5,798,368
• PCT/US1997/013375 (1997-07-24) → WO 98/03502
• US 09/543,809 (2000-04-06) → US 6,281,230
• US 09/781,179, filed 2001-02-12, granted 2003-04-29

Original assignee

Celgene Corporation (Summit, New Jersey) — named as original assignee on the issued patent.

• Primary line of business: Integrated biopharmaceutical company (small-molecule and biologic oncology/immunology). At the 1996 priority date Celgene was a mid-cap biotech; by filing/issue it was a commercial-stage pharma.
• Product embodying the claims: Yes. The '554 specification/abstract expressly names the compound lenalidomide (1‑oxo‑2‑(2,6‑dioxopiperidin‑3‑yl)‑4‑aminoisoindoline), marketed as REVLIMID®. The '554 patent is listed in the Orange Book for NDA 021880 (REVLIMID, Celgene), with listed expiry 2016-07-24 (use code U‑1211). This is a direct commercial embodiment of the claimed genus.
• Current status: Operating (now part of Bristol Myers Squibb). BMS acquired Celgene — announced 2019-01-03, closed 2019-11-20; Celgene continued as a BMS subsidiary and the REVLIMID franchise transferred with it. Google Patents lists the current assignee as Celgene Corp with no post-issuance reassignment event surfaced — consistent with Celgene's separate corporate identity persisting inside BMS rather than a recorded "change of name" event on this patent.
• Patent status: Expired – Lifetime; anticipated expiration 2016-07-24. It is unenforceable today, which materially blunts any current NPE-story framing.

Assignment timeline

No recorded assignment data was retrieved for US 6,555,554. USPTO Assignment Center / Patent Assignment Search returned nothing retrievable through my tooling, and Google Patents' legal-events feed for this patent shows only litigation, publication, grant and expiration events — no reassignment entries. I therefore cannot list reel/frame, execution/recording dates, conveyance types or correspondents, and I will not synthesize them.

What can be stated about conveyances from the record in hand:

• A pre-issuance inventor→Celgene assignment is presumed for a 1996/2001 corporate-employee filing, but the reel/frame, execution date and correspondent are not verified (do not rely on this as a finding).
• No third-party or LLC assignment appears in any source I could reach. The patent's front page, the Orange Book listing, the D.N.J. docket, and the Unified Patents/Google family pages all carry Celgene Corp as owner/plaintiff throughout.
• The only "transfer" narrative in the public record is the corporate M&A event of 2019-11-20 (Celgene into BMS), which is a parent-level acquisition, not a patent-record conveyance that I could confirm.

Verification links (search by patent number 6555554 at each):

• USPTO Assignment Center — https://assignmentcenter.uspto.gov/
• USPTO Patent Assignment Search (legacy) — https://assignment.uspto.gov/patent/index.html
• Google Patents legal events — https://patents.google.com/patent/US6555554/en
• Darts-ip family litigation — https://patents.darts-ip.com/?family=24771755
• Unified Patents litigation record — https://portal.unifiedpatents.com/litigation/New%20Jersey%20District%20Court/case/2%3A10-cv-05197

Timeline diagram

timeline
    title Ownership and assertion of US 6555554
    1996 : Priority date 1996-07-24
         : Filed in Celgene continuation family
    2001 : Application 09781179 filed
    2003 : Patent granted 2003-04-29
         : Celgene Corp named assignee
    2005 : REVLIMID approved NDA 021880
    2010 : Celgene sues Natco in D NJ
    2016 : 554 patent dropped by stipulation
         : Patent expires 2016-07-24
    2019 : BMS acquires Celgene

NPE / troll-pattern signals

Because no assignment documents were retrieved, several signals are undecidable on the record. I mark them honestly rather than inferring from names.

Additional context that cuts against any NPE framing:

• The '554 patent was asserted by Celgene, in Celgene's own name, in Celgene's own infringement action — the definitional opposite of an NPE transfer pattern.
• Celgene stipulated to dismissal of the '230 and '554 patent claims after the D.N.J. Markman ruling adopted Natco's proposed claim constructions limiting the claims to specific stereochemical configurations of lenalidomide; the case terminated 2016-01-05. The '554 claims were narrowed out of the case rather than farmed to an asserter.
• The patent expired 2016-07-24, before any later corporate restructuring — so no post-expiry assertion or acquisition-for-litigation is possible.

Verdict

Operating-company assertion.

Justification: the patent's owner of record and the sole plaintiff in the only actions naming the '554 patent is Celgene Corporation — the company that commercialized the claimed compound as REVLIMID® (NDA 021880, Orange Book–listed against the '554 patent with a 2016-07-24 expiry) — and it asserted the patent in Celgene Corp. v. Natco Pharma Ltd., 2:10-cv-05197 (D.N.J.), filed 2010-10-08 and terminated 2016-01-05, against an actual generic competitor. No assignment to any licensing entity, aggregator, or known NPE appears in any source I could reach, and the only ownership-relevant corporate event is the BMS acquisition of Celgene (closed 2019-11-20), a parent-level M&A transaction involving an operating manufacturer. Because I could not retrieve reel/frame records from USPTO Assignment Center, the repeat-correspondent signal remains genuinely unevaluated rather than negative — verify at https://assignmentcenter.uspto.gov/ by searching patent 6555554 before relying on this section for a formal ownership opinion.

I'll research the patent's cited references and prior art record.

Let me pull the complete front-page reference list for this patent.

Let me retrieve the remainder of the cited-reference list (U.S. patents, foreign documents, and NPL).

Scope note before the analysis

You asked me to search the USPTO database for the specific number 6555554 and to report the patent citations on that document. What I was able to retrieve:

• The front-page "Referenced Cited" list for US 6,555,554 as reproduced by Justia's copy of the granted patent (https://patents.justia.com/patent/6555554) — but the U.S. patent list is truncated in the retrievable text (it cuts off at "56589…").
• The cited non-patent literature for US 6,555,554 as reproduced on the PubChem patent record (https://pubchem.ncbi.nlm.nih.gov/patent/US-6555554-B2).
• The family / "Similar Documents" data on Google Patents (https://patents.google.com/patent/[US6555554B2](/patent/US6555554B2)/en).

I could not directly open USPTO Patent Center or Patent Public Search in this session, and I could not retrieve (i) the complete U.S.-patent portion of the front-page reference list, or (ii) the "Foreign Patent Documents" list for this specific document. I did not substitute any similar number — everything below is keyed to 6,555,554 only. Where I could not verify a reference's subject matter with high confidence, I say so rather than guess.

1. The date framework that governs the §102 analysis (critical)

Because 09/781,179 is a continuation carrying benefit back to the 1996 family, the operative prior-art date is 1996-07-24 (or 1996-08-22), and pre-AIA 35 U.S.C. §102 applies. That single fact radically changes the answer you'd otherwise expect, and it is the main finding of this analysis:

• §102(b) art must predate 1995-07-24 (one year before the priority date).
• References that issued/published in 1997–1999 are, on their face, not §102 prior art — they are either the applicant's own family members or later background literature. Many of the entries below fall in this bucket.
• References with pre-1996-07-24 filing dates can still be §102(e) art even though they issued in 1997.

⚠️ Contradiction flag (must not be glossed over): the previously generated section states the granted claims are "directed to the 1-oxo (isoindoline) genus." The specification's own Formula I definition, however, recites that "one of X and Y is C=O and the other of X and Y is C=O or CH₂" — which on its face sweeps in the 1,3-dioxo (phthalimide) compounds as well. Which reading is correct controls whether the known amino-phthalimides (Jönsson 1972 and the family's own phthalimide patents) can anticipate. I could not machine-read the claim formulas to resolve this; treat the §102 conclusions below as conditional on that point.

2. U.S. patent documents cited on the face of US 6,555,554

Verified entries (as reproduced by Justia for the '554 grant):

List truncation warning. The Justia reproduction of the '554 "Referenced Cited" list is cut off at US 5,658,940, and the retrievable snippets for the closely related Celgene patents (US 7,329,761; US 10,092,555; US 9,822,093) show the same block of U.S. references recurring (5,463,063 / 5,635,517 / 5,658,940 / 5,798,368 / 5,874,448 / 5,929,117 / 5,955,476). It is therefore likely, but not verified, that US 5,798,368 (Aug 25, 1998 — tetrasubstituted 2-(2,6-dioxopiperidin-3-yl)-1-oxoisoindolines), US 5,874,448 and US 5,955,476 (3-fluoropiperidin-3-yl isoindolines), and US 5,929,117 also appear on the '554 face. I am flagging these as unverified rather than asserting them. All of them issued in 1998–99, i.e. after the priority date, so absent pre-1996-07-24 filing dates none is §102(a)/(b) art.

3. Foreign patent documents

I could not retrieve the "Foreign Patent Documents" block for 6,555,554 itself. For transparency, the reference blocks of related Celgene documents include GB 858 086 (Jan 1961) and WO 95/01348 (Jan 1995) (both pre-1996, therefore theoretically §102(b) candidates if their disclosures reach the claimed genus), and — importantly — WO 98/03502 (published Jan 29, 1998) and WO 98/54170 (published Dec 1998).

Note the trap here: WO 98/03502 is not prior art against '554 — it is the PCT publication of the very same 1996 priority application (PCT/US1997/013375 → US 08/701,494 → US 6,281,230 → this case), and WO 98/54170 is the sibling Celgene filing. They cannot anticipate '554 because they are same-family documents published after the priority date. Any automated prior-art report that lists them as §102 art is wrong.

4. Non-patent literature cited (verified list from the PubChem record for US 6,555,554)

High-value entries, with §102 assessment:

• Jönsson, N., "Chemical Structure and Teratogenic Properties," Acta Pharm. Suecica, 9, 431–446 and 521–542 (1972). — ⚑ This is the single most dangerous §102(b)-type reference on the patent. The '554 specification itself admits: "Compounds in which one of R¹…R⁴ is amino … as for example, 1,3-dioxo-2-(2,6-dioxopiperidin-3-yl)-4-aminoisoindoline or …5-aminoisoindoline are known. See, e.g. Jönsson, Acta Pharma. Suecica, 9, 521-542 (1972)." If claim 1 or claim 10 read on the 1,3-dioxo genus (see the X/Y contradiction flagged above), Jönsson is applicant-admitted §102(b) prior art for those species.
• Muller, G. et al., "Structural Modifications of Thalidomide Produce Analogs with Enhanced TNF Inhibitory Activity," J. Med. Chem. 39(17), 3238–3240 (1996). — the inventors' own paper. Published ~August 1996, after the 1996-07-24 priority date → not prior art. (It would only become §102(b) if the claims were denied the 1996 benefit and dated from 2001-02-12.)
• Muller, G. et al., "Amino-Substituted Thalidomide Analogs: Potent Inhibitors of TNF-α Production," Bioorg. Med. Chem. Lett. 9, 1625–1630 (1999). — post-priority; background/§103 only.
• Miyachi, H. et al., J. Med. Chem. (1997) 2858–2865 and Chem. Pharm. Bull. 46(7), 1165–1168 (1998); Niwayama, S. et al., J. Med. Chem. 39, 3044–3045 (1996) and Bioorg. Med. Chem. Lett. 8, 1071–1076 (1998); Shannon, E.J. et al., Immunopharmacology 35, 203–212 (1997); Takeuchi, Y. et al., Org. Lett. 1(10), 1571–1573 (1999); He, W. et al., 206th ACS Nat'l Mtg, Med. Chem. Abst. 216 (1993); Koch, H., Prog. Med. Chem. 22, 166–242 (1985) and Sci. Pharm. 49, 67–99 (1981); Smith, R.L. et al., Symp. Embryopathic Act. Drugs, 194–209 (1965); Zwingenberger, K. et al., J. Inflammation 46, 177–211 (1996); Udagawa, T. et al., Antiangiogenic Agents in Cancer Therapy, 263–274. — all background/thalidomide-SAR art; only the pre-July-1996 items (Koch 1985, Smith 1965, He 1993) are even §102(b)-eligible, and none is disclosed to reach the claimed 1-oxo glutarimide isoindolines.

5. Bottom line — the most relevant prior art for 6,555,554

Ranked by actual §102 exposure, not by count:

1. Jönsson, Acta Pharm. Suecica 9, 521–542 (1972) — applicant-admitted prior art for the amino-substituted 1,3-dioxo (phthalimide) glutarimides. Anticipatory only if claims 1/10 cover X=Y=C=O. This is the reference a challenger would lead with.
2. US 5,635,517 (Muller et al., Jun 3, 1997) — the U.S. patent most likely to be §102(e) art against claims 1 and 10, because later Celgene filings credit it with disclosing both 1-oxo and 1,3-dioxo 2-(2,6-dioxopiperidin-3-yl)isoindolines.
3. US 4,849,441 (Okazaki et al., Jul 18, 1989) — the closest structural prior art to the isoindolin-1-one nucleus; §103 rather than §102.
4. US 5,463,063 (Muller, Oct 31, 1995) / US 5,502,066 (Heinemann et al., Mar 26, 1996) — the only two cited U.S. patents that fall before the priority date and are therefore §102(a) (swear-behind-able) rather than §102(e) art.
5. Everything dated 1997–1999 (US 5,593,990; 5,605,914; 5,629,327; 5,658,940 and the family companions) — citable only via §102(e)/§103, and only if their underlying applications predate 1996-07-24.

No reference on the face of the patent appears to have been applied as a §102 anticipation against the granted claims — consistent with the patent having issued with claims 1–17 intact and expiring naturally in 2016 with no reissue, reexamination, or IPR/PGR record surfaced in my searches.

Limitations I want on the record

1. The claim formulas are images and were not machine-readable; I could not verify whether claim 1 recites 1-oxo only or the broader X/Y genus. Every §102 conclusion keyed to the phthalimide prior art is conditional on that.
2. The U.S. reference list is truncated in the source I could retrieve (ends at "56589…"); entries after US 5,658,940 are inferred from sibling patents, not confirmed for '554.
3. I could not retrieve '554's own Foreign Patent Documents column or the examiners' applied-art record from USPTO Patent Center; those should be pulled from the granted-PDF front page or Patent Public Search for a definitive citation set.
4. Subject matter for US 4,590,189, 5,385,901, 5,502,066 and 5,658,940 was not independently verified; I did not guess at it.

I'll ground this analysis in the prior art actually identified on the patent's page and in its specification. Let me pull the reference list and family/prosecution context.

Let me pull the actual "References Cited" on the '554 front page and check for any validity challenges that identify specific art combinations.

Obviousness Analysis — US 6,555,554 B2 under 35 U.S.C. § 103

0. Scope of this analysis and one flagged contradiction

This builds on the previously generated sections (identification, claim set, litigation check) and does not repeat them. One explicit contradiction must be flagged first:

Contradiction flag. The earlier summary concluded "the granted claims directed to the 1‑oxo (isoindoline) genus." But the granted claim text (claim 1 proviso) as reported by DrugPatentWatch — "provided that R⁶ is other than hydrogen if X and Y are C=O and (i) each of R¹–R⁴ is fluoro or (ii) one of R¹–R⁴ is amino" — only makes sense if claim 1 also embraces the 1,3‑dioxo (phthalimide) members. The title/abstract ("Isoindolines," "substituted 1‑oxo‑2‑(2,6‑dioxopiperidin‑3‑yl)isoindolines") emphasize the 1‑oxo subgenus. Because the claim-formula images were not machine-readable, I treat claim 1 as at minimum covering the 1‑oxo genus and arguably the full X/Y = C=O-or-CH₂ Markush with the R⁶ proviso, and I analyze both. This materially affects the § 103 result for the amino species (see § 4, claim 1).

Governing law. 35 U.S.C. § 103(a); Graham v. John Deere Co., 383 U.S. 1 (1966); KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007). In chemistry, structural similarity to a prior-art compound having the same utility creates a prima facie case of obviousness (In re Papesch, 315 F.2d 381 (CCPA 1963); In re Dillon, 919 F.2d 688 (Fed. Cir. 1990) (en banc)). "Obvious to try" is enough where the variation is a finite, predictable set (KSR).

1. What the "Prior Art" panel of this page actually surfaces

Google Patents' prior-art panel for US 6,555,554 gives:

• Prior-art keywords: compound, oxo, mixture, pharmaceutical composition, dioxopiperidin — i.e., the field is defined by the glutarimide ("dioxopiperidin") + "oxo"‑isoindoline pharmacophore in a pharmaceutical composition.
• Prior-art date: 1996‑07‑24.
• Family/priority documents (these are not available as § 102/103 art, same inventive entity + common ownership): US 5,798,368; WO 98/03502; US 6,281,230 (and the siblings US 6,476,052, US 7,119,106, etc.).

The substantive art is the material the patent itself cites, both as background and as the admitted known compounds:

• Jönsson, Acta Pharma. Suecica, 9, 521‑542 (1972) — cited in the specification at [0027] as disclosing 1,3‑dioxo‑2‑(2,6‑dioxopiperidin‑3‑yl)-4‑aminoisoindoline and ‑5‑aminoisoindoline. The same author's companion paper, Acta Pharm. Suec. 9, 431‑436 (1972), is titled (per the reference list in later Celgene filings) "…Derivatives of Phthalidomide, Isoindoline‑1‑one, 1,2‑Benzisothiazoline‑3‑one‑1,1‑Dioxide and 4(3H)-Quinazolinone" — i.e., Jönsson expressly studied the 1‑oxo (isoindolin‑1‑one) ring as a thalidomide analog. (Confirmed via the Jönsson reference lists at US 6,673,828 and FI120687B.)
• TNFα background/utility art: Tracey et al., Nature 330, 662‑664 (1987); Hinshaw et al., Circ. Shock 30, 279‑292 (1990); Bertolini et al., Nature 319, 516‑518 (1986); Johnson et al., Endocrinology 124(3), 1424‑1427 (1989); Leibovich et al., Nature 329, 630‑632 (1987) (and US 4,808,402, Leibovich); Beutler et al., Science 234, 470‑474 (1985); Duh/Osborn/Folks (PNAS 1989); Elliot et al. (1995); von Dullemen et al. (1995) — all pre‑1996 and all § 102(b) art.
• **US 5,385,901 (Kaplan et al., Jan. 31, 1995)** — "Method of treating abnormal concentrations of TNFα"; cited in the sibling US 6,281,230 art list. Different inventor/assignee ⇒ genuine prior art.
• *Shealy et al., Chem. Ind. (London) 1965, 1030‑1031* ("D‑ and L‑thalidomide") and Wilen, Tables of Resolving Agents and Optical Resolutions (1972) — cited in the family; support the stereochemistry claims.
• Formulation/salt law: Berge et al., J. Pharm. Sci. 66, 1‑19 (1977) (physiologically acceptable salts), plus the specification's own admissions at [0028]–[0035] that the synthetic methods are "known in general" and the nitro/benzoate intermediates "are known or can be obtained through conventional processes."

PHOSITA: a medicinal chemist (Ph.D./M.S. + 2–5 yrs) in small-molecule cytokine/immunomodulator discovery, conversant with thalidomide SAR, glutarimide/phthalimide chemistry, and standard TNFα assays (LPS‑stimulated PBMC/monocyte TNFα release).

2. The single most important difference over the art

The compounds the specification admits are known (Jönsson) are the 1,3‑dioxo (phthalimide) amino species. The '554's claimed advance is essentially:

1. X = C=O, Y = CH₂ — i.e., one carbonyl of the phthalimide replaced by a methylene, giving the 1‑oxo isoindoline ("Isoindolines"); and
2. putting R⁶ ≠ H (alkyl/benzyl/halo) at the glutarimide 3‑position; and
3. the new use/compositions (TNFα reduction, oncologic/inflammatory/autoimmune indications).

This is, chemically, a carbonyl→methylene homologation of a known ring system sharing the identical glutarimide pharmacophore. That is the crux of the obviousness case.

3. Motivation to combine — why a PHOSITA would have made this

• Jönsson itself supplies the bridge. Jönsson (1972, paper I) studied the isoindolin‑1‑one scaffold as a thalidomide analog alongside phthalidomide. Once that paper teaches the two ring systems are interchangeable analogs of the same class, converting the known 4‑/5‑amino phthalimidoglutarimides to their 1‑oxo counterparts is an obvious, finite, predictable variation (In re Papesch/Dillon; KSR "predictable variations of known compounds").
• The utility was known and the motivation explicit. Kaplan (US 5,385,901) and the Tracey/Beutler literature taught that the glutarimide/thalidomide class suppresses TNFα. A PHOSITA would therefore predict that ring-modified members of the same class retain the same TNFα‑suppressing utility — supplying "a reasonable expectation of success."
• Design incentive to modify. Thalidomide's teratogenicity/toxicity and its metabolic liability created an express market/clinical incentive to modify the ring system and the glutarimide (the "inventive incentive" recognized in KSR). Replacing a metabolically labile/more polar carbonyl with CH₂, and alkylating the glutarimide 3‑position, are textbook lipophilicity/stability manipulations.
• Synthetic predictability. The '554 specification itself states the 1‑oxo compounds are made by standard chemistry — reaction of 2,6‑dioxopiperidin‑3‑ammonium chloride with a lower‑alkyl 2‑bromomethylbenzoate, or selective reduction of a phthalimide intermediate. No new chemistry was required.

4. Claim‑by‑claim § 103 mapping

Representative three‑reference combination (strongest):

1. Jönsson 1972 (9:521‑542) — known 4‑/5‑amino‑1,3‑dioxo glutarimides; Jönsson 1972 (9:431‑436) — the 1‑oxo isoindolinone analog;
2. Kaplan US 5,385,901 — TNFα‑lowering utility of the thalidomide/glutarimide class;
3. Shealy 1965 + Wilen 1972 (for the enantiomer claims), with Berge 1977 / conventional formulation for the composition/dosage‑form claims.

5. Anticipated counter‑arguments and the § 103 caveats

• Same‑family documents are not art. US 5,635,517, US 5,798,368, US 6,281,230, WO 98/03502, US 6,476,052, etc. share the same three inventors and Celgene ownership and the same Jul. 24, 1996 priority; they are not "by another" and cannot support a § 102/§ 103 rejection. Any attack must rest on Jönsson, Kaplan, Shealy, Wilen, D'Amato‑era art, and the general TNFα literature — not on Celgene's own later patents. (Notably, the reverse has happened: the '554 itself has been used as prior art against later Celgene patents — see Celgene v. Hetero, D.N.J. 2:17‑cv‑03387, CourtListener entry combining art "taken further in view of US 6,555,554.")
• The examiner allowed the claims, implying the specific 1‑oxo/R⁶‑non‑hydrogen genus was viewed as non‑obvious; a challenger bears the burden of showing the examiner overlooked Jönsson's isoindolinone teaching or the Kaplan utility teaching.
• Secondary considerations (Graham factor 4). Celgene would point to (i) the long‑felt need for a non‑teratogenic, better‑tolerated TNFα modulator; (ii) the unexpected superior potency/cytokine profile of lenalidomide versus thalidomide (reported by the inventors in Bioorg. Med. Chem. Lett. 9, 1625‑1630 (1999)); and (iii) the commercial success of REVLIMID. The rebuttal's weakness is nexus: the claims are a broad genus that reads on the admitted‑known Jönsson species, so the unexpected properties of one species (lenalidomide) may not be coextensive with the claim scope — the classic nexus problem for genus claims.
• Adjacent (non‑§ 103) invalidity theory to note: because the '554 and the earlier‑issued '517/'368 share a priority chain and overlapping subject matter, obviousness‑type double patenting would be a separate line of attack.

6. Bottom line

On the record available, claims 1–17 would be vulnerable to a § 103 challenge mounted on Jönsson 1972 (both papers) as the closest art, Kaplan US 5,385,901 / the TNFα literature for the utility, and Shealy 1965 / Wilen 1972 for the enantiomer limitations, with routine‑formulation and salt law (Berge 1977, and the patent's own admissions at [0028]–[0035]) covering claims 4–9 and 16–17. The decisive weakness is that the sole structural distinctions — the carbonyl→CH₂ ring contraction to the 1‑oxo isoindoline and C1‑8 alkylation at the glutarimide 3‑position — were explicitly taught or rendered predictable by Jönsson's own isoindolin‑1‑one thalidomide‑analog work and by routine medicinal‑chemistry practice, i.e., an "obvious to try" variation with a reasonable expectation of success under KSR, and a Papesch/Dillon structural‑similarity case because the prior‑art compounds share the class's TNFα‑suppressing utility.

Confidence/limitations: (i) I could not machine‑read the granted claim‑formula images, so the precise outer boundary of claim 1 (1‑oxo‑only vs. full X/Y Markush) is uncertain — see the flagged contradiction in § 0; (ii) I confirmed no IPR specifically on the '554, but the family has been challenged (e.g., the 1998 ex parte reexamination 90/005,157 and IPR2015‑01169 both on family member US 5,635,517); (iii) reference‑list details for the front page were taken from secondary aggregators (DrugPatentWatch, uspto.report) rather than a direct USPTO Patent Center query and should be re‑verified before any validity opinion is relied upon.