US 12161628

Summary of U.S. Patent No. 12,161,628

Title: Combination therapy

Assignee: Astellas Pharma Inc., Medivation Prostate Therapeutics LLC

Inventors: Jacqueline GIBBONS, Joyce MORDENTI, Michiel DE VRIES, Walter KRAUWINKEL, Taoufik Ouatas

Filing Date: October 4, 2022

Issue Date: December 10, 2024

Abstract: This disclosure provides a dosage regimen for co-administration of enzalutamide and a strong CYP3A4 inducer.

Independent Claims Overview

The patent contains one independent claim, Claim 1. The subsequent claims (2-6) are dependent on Claim 1, narrowing its scope.

Claim 1: Plain-Language Overview

Claim 1 of patent 12,161,628 describes a method for treating prostate cancer. The method applies to a patient who is already being treated with a drug called rifampin. The core of the patented method is to also give this patient a daily dose of 240 mg of another drug, enzalutamide. In essence, the invention is the specific use of a 240 mg daily dose of enzalutamide in prostate cancer patients who are also taking rifampin.

Litigation Status

As of early 2026, U.S. Patent 12,161,628 has been the subject of litigation. Court records indicate its involvement in a case in the U.S. District Court for the District of New Jersey: Astellas Pharma Inc. v. Hikma Pharms. USA Inc., 25-0578 (D.N.J.). The records show that the claims and counterclaims in this case were dismissed with prejudice, with each party bearing its own costs. A search of the U.S. Court of Appeals for the Federal Circuit (CAFC) dockets for 2026 did not yield specific results for this patent number, though district court decisions are often appealed to the CAFC.

Multiple Lawsuits Filed Against Generic Drug Makers Over Prostate Cancer Treatment Patent

As of May 7, 2026, U.S. Patent No. 12,161,628, which covers a combination therapy for prostate cancer, is at the center of several lawsuits filed by owner Astellas Pharma Inc. and other related entities. The lawsuits, all filed in the U.S. District Court for the District of New Jersey, target pharmaceutical companies seeking to market generic versions of Astellas's drug, Xtandi® (enzalutamide). The core of the patent's Claim 1 is a "method of treating prostate cancer in a patient to whom rifampin is administered, comprising co-administering to the patient a daily dose of 240 mg enzalutamide."

The litigations are a response to Abbreviated New Drug Applications (ANDAs) filed with the U.S. Food and Drug Administration (FDA) by the generic manufacturers, a standard procedure for seeking approval of generic drugs. The plaintiffs allege that by filing these ANDAs, the defendants are infringing on the '628 patent.

Known litigation involving U.S. Patent 12,161,628 includes the following cases:

1. Astellas Pharma Inc. et al v. Hikma Pharmaceuticals USA Inc.

• Jurisdiction: U.S. District Court for the District of New Jersey
• Case Number: 3:25-cv-00578
• Filing Date: January 16, 2025
• Plaintiffs: Astellas Pharma Inc., Astellas US LLC, Astellas Pharma US, Inc., Medivation LLC, Medivation Prostate Therapeutics LLC
• Defendant: Hikma Pharmaceuticals USA Inc.
• Outcome/Status: The claims and counterclaims in this case were dismissed with prejudice, with each party bearing its own costs. This confirms the information from the previously generated summary.

2. Astellas Pharma Inc. et al v. Haimen Pharma Inc. et al

• Jurisdiction: U.S. District Court for the District of New Jersey
• Case Number: 3:24-cv-09403
• Filing Date: The original complaint was filed in 2024, with an amended complaint that included the '628 patent filed on January 3, 2025.
• Plaintiffs: Astellas Pharma Inc., Astellas US LLC, Astellas Pharma US, Inc., Medivation LLC, Medivation Prostate Therapeutics LLC, The Regents of the University of California
• Defendants: Haimen Pharma Inc., SinoTherapeutics Inc.
• Outcome/Status: This case has been consolidated with case 3:24-cv-09748 for all purposes. All future filings are to be made in the '9403 case. The case appears to be ongoing.

3. Astellas Pharma Inc. et al v. Zydus Pharmaceuticals (USA) Inc. et al

• Jurisdiction: U.S. District Court for the District of New Jersey
• Case Number: 3:24-cv-09748
• Filing Date: October 11, 2024. An amended complaint including the '628 patent was filed on January 3, 2025.
• Plaintiffs: Astellas Pharma Inc., Astellas US LLC, Astellas Pharma US, Inc., Medivation LLC, Medivation Prostate Therapeutics LLC
• Defendants: Zydus Pharmaceuticals (USA) Inc., Zydus Lifesciences Ltd.
• Outcome/Status: This case has been consolidated with case 3:24-cv-09403 and appears to be ongoing.

4. Astellas Pharma Inc. et al v. Ascent Pharmaceuticals, Inc. et al

• Jurisdiction: U.S. District Court for the District of New Jersey
• Case Number: 3:25-cv-00035
• Filing Date: January 2025
• Outcome/Status: Mentioned in court filings for the Hikma case, but further details on the specific defendants and current status are not available in the provided search results.

In addition to the cases listed above, the patent's Google Patents page indicates two other lawsuits in the same jurisdiction, 3:25-cv-15434 and 3:25-cv-13779, though specific details about these cases were not found in the immediate search results. The pattern of litigation suggests an active enforcement strategy by Astellas to protect its market for Xtandi®.

The USPTO ODP API previously indicated no AIA trial proceedings for US patent 12161628. My web searches for "US12161628 PTAB IPR", "US12161628 PTAB PGR", "US12161628 PTAB CBM", and related terms also did not directly yield any specific PTAB proceeding numbers (IPR, PGR, CBM) for US Patent 12,161,628.

The search results primarily discuss the patent's content, its litigation in district court (e.g., Astellas Pharma Inc. et al v. Hikma Pharmaceuticals USA Inc., 3:25-cv-00578), and general information about IPR and PGR proceedings. One search result from DrugPatentWatch briefly mentions "WO2017027665 · ⤷ Start Trial", which refers to an international application and not directly to the US patent 12,161,628, nor does it provide an actual PTAB trial number. It seems to be a feature of their platform rather than an active PTAB case.

Given the patent was issued on December 10, 2024, the nine-month window for filing a Post-Grant Review (PGR) (which allows challenges on any ground, including novelty, obviousness, and written description, within nine months of issuance) would still be open until around September 10, 2025. Inter Partes Review (IPR) (which can only be based on prior art under §§ 102 or 103) can typically be filed after the later of nine months after the patent grant or the termination of any PGR.

Therefore, as of today's date (2026-05-30), it is plausible that no PGR was filed within the initial 9-month window, and the earliest an IPR could typically be filed would be after September 2025 (or after any PGR concluded). However, my search did not identify any such filings.

The absence of PTAB proceedings for a relatively newly granted patent, especially one involved in active district court litigation, is notable. This could indicate that potential challengers are still evaluating their options, or that the patent owners have strategically engaged in settlement discussions that preclude PTAB challenges, or that the claims are perceived as robust enough to discourage PTAB challenges at this time.

Proceedings overview

There are no AIA trial proceedings (Inter Partes Review, Post-Grant Review, or Covered Business Method review) on file for U.S. Patent 12,161,628 as of the most recent data from the USPTO Open Data Portal and supplementary web searches. This indicates that all claims (1-6) of the patent remain untested at the PTAB.

Strategic summary

As of May 30, 2026, U.S. Patent 12,161,628 has no PTAB trial proceedings on record. This means that all six claims of the patent, including the independent Claim 1 and its dependent claims 2-6, have not been challenged or adjudicated before the Patent Trial and Appeal Board. Consequently, all claims are currently sustained as granted by the USPTO and remain untested in an administrative trial setting.

The absence of PTAB activity is particularly noteworthy given that the patent is involved in multiple district court litigations against generic drug manufacturers (e.g., Astellas Pharma Inc. et al v. Hikma Pharmaceuticals USA Inc., 3:25-cv-00578). In such Hatch-Waxman disputes, defendants often simultaneously pursue PTAB challenges to the asserted patents. The patent was issued on December 10, 2024, making it eligible for Post-Grant Review (PGR) for nine months following its issuance, which concluded around September 10, 2025. Inter Partes Review (IPR) could typically be filed after that period or later. No such filings were found.

The current estoppel landscape is entirely open. Since no PTAB proceedings have occurred, there are no prior art grounds that have been "raised or reasonably could have been raised" and subsequently barred from future challenges under 35 U.S.C. § 315(e)(2). Therefore, any potential defendant still has the full range of prior art grounds (under §§ 102 and 103 for IPR, or broader grounds including § 101 and § 112 for PGR if applicable) available for a future PTAB challenge, should they choose to initiate one.

Recommended next steps

• No PTAB activity exists. The absence of any Inter Partes Review, Post-Grant Review, or Covered Business Method proceedings for U.S. Patent 12,161,628 means that the patent's validity has not been challenged or decided by the PTAB. This is an important signal, as patents involved in active litigation often face such challenges.
• Monitor for future filings. Any party interested in challenging this patent's validity should continue to monitor the USPTO's Patent Trial and Appeal Case Tracking System (P-TACTS) for new IPR or PGR petitions. Given the ongoing district court litigation, future PTAB challenges remain a possibility.
• Evaluate prior art for IPR. For a defendant currently facing assertion of this patent, an IPR petition could still be a viable strategy, as all claims remain untested. The grounds for IPR are limited to novelty (§ 102) and obviousness (§ 103) based on patents and printed publications. The prior art analyzed in the "Obviousness" section (WO2017027660A1, for example) could be a basis for such a challenge.
• Consider a PGR if within the 9-month window. While the 9-month window for PGR has likely passed (patent issued December 10, 2024), if a reissue patent were to issue, a new PGR window might open. PGR allows for a broader range of invalidity grounds beyond just prior art.

I'll research the assignment chain for US 12,161,628. Let me start with the records already surfaced in the patent text and cross-reference ownership via web searches.

Let me dig into the specific recording details and any correspondent information.

Assignment & Ownership Analysis — U.S. Patent No. 12,161,628

Patent: US 12,161,628 B2 ("Combination therapy")
Application: 17/959,350 (filed 2022-10-04; continuation of 17/706,788 → 15/751,542 → PCT/US2016/046476)
Priority: 2015-08-12
Issued: 2024-12-10

Sourcing caveat (read first): The USPTO Assignment Center / Assignment Search (assignmentcenter.uspto.gov) was retired and replaced effective 2025-09-27; the underlying database is the same. I was able to reconstruct the chain from the Google Patents "Legal Events / Reassignments" extract included in the authoritative patent text, which reproduces USPTO reel/frame records, conveyance types, assignors, assignees, and effective/recording dates. The correspondent of record (recording attorney/firm) is not reproduced in the fetched USPTO-derived data, and my supplemental searches did not return a corroborated correspondent name for reels 069516/xxxx or 069495/xxxx. I therefore do not name a correspondent rather than fabricate one. All reel/frame figures below are quoted from the patent's legal-events record; verify at https://assignmentcenter.uspto.gov/.

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Inventors

Named inventors on the issued patent:

Additional assignors who appear in the assignment record but are not on the printed inventor list: the 2016 assignment of inventors' interest (reel 069495/0311) also covers Lynn Seely, Mohammad Hirmand, and Cheryl Madsen (all Medivation). These are almost certainly inventors of the 2015 provisional applications (62/204,281 and 62/204,954) who were dropped from the issued claim set.

Pattern note: The Medivation-side inventors executed their assignment in February 2016 — roughly six months before Pfizer's 2016-08-22 announcement of its ~$14B acquisition of Medivation. That timing is a normal pre-acquisition housekeeping event, not a fire-sale tell. The Astellas-side "confirmatory assignments" were executed later (2017 and 2019) — these are curative documents confirming rights the two companies were already exercising jointly under the 2009 Medivation–Astellas enzalutamide collaboration, not new transfers.

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Original assignee

Medivation Prostate Therapeutics, Inc. (renamed Medivation Prostate Therapeutics LLC), jointly with Astellas Pharma Inc. (Japan).

• Product embodying the claims: Yes — XTANDI® (enzalutamide). Claim 1 recites a method of treating prostate cancer with 240 mg/day enzalutamide in a patient on rifampin, which is a dosing method for a commercially marketed, FDA-approved drug (first approved Sept. 2012; US net sales in the billions annually). This is a drug-patent, not an abstract method patent.
• Primary business: Oncology-focused biopharmaceutical development/commercialization (Medivation) and full-scale pharmaceutical R&D/commercialization (Astellas).
• Current status of the original assignee entity: Operating. Medivation, Inc. was acquired by Pfizer Inc. in 2016; Medivation Prostate Therapeutics LLC is a Pfizer subsidiary — the assignment records show its recorded address migrating to Pfizer's New York headquarters (235 East 42nd Street, then 66 Hudson Boulevard East, New York, NY 10001-2192), which is Pfizer's corporate address, not a registered-agent service address. Astellas Pharma Inc. remains an independent, listed operating company. No dissolution, bankruptcy, or wind-down appears anywhere in the chain.

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Assignment timeline

Chronological, from the USPTO-derived legal-events record. (Executed/effective date first, then recording date, then reel/frame.)

• Executed 2016-02-03 → 2016-02-17 / recorded 2024-12-05 — Reel 069495/0311 (and duplicate 069495/0448)

  • Conveyance: Assignment of assignors' interest (inventor → company)
  • Assignor: Joyce Mordenti; Jacqueline Gibbons; Lynn Seely; Mohammad Hirmand; Cheryl Madsen
  • Assignee: Medivation Prostate Therapeutics, Inc. (California)
  • Correspondent: Not determinable from the available record. (See sourcing caveat.)
  • Context: Original inventor-to-company assignment; note the ~9-year gap between execution (2016) and recordation (2024), i.e., a late/curative recording filed on the eve of issuance and litigation.

• Executed/effective 2017-08-25 / recorded 2024-12-05 — Reel 069516/0437

  • Conveyance: Change of Name
  • Assignor: Medivation Prostate Therapeutics, Inc.
  • Assignee: Medivation Prostate Therapeutics LLC (California)
  • Correspondent: not determinable
  • Context: Internal corporate reorg / name change only (Inc. → LLC), consistent with the post-Pfizer acquisition entity structuring. No change of beneficial owner.

• Executed 2017-09-26 / recorded 2024-12-05 — Reel 069516/0398

  • Conveyance: Confirmatory Assignment
  • Assignor: Michiel de Vries; Walter Krauwinkel
  • Assignee: Astellas Pharma Inc. (Japan)
  • Correspondent: not determinable
  • Context: Curative/confirmatory internal recordation of Astellas-side inventor rights already contemplated by the 2009 Medivation–Astellas collaboration.

• Executed/effective 2019-11-08 / recorded 2024-12-05 — Reel 069516/0435

  • Conveyance: Confirmatory Assignment
  • Assignor: Taoufik Ouatas
  • Assignee: Astellas Pharma Inc. (Japan)
  • Correspondent: not determinable
  • Context: Confirmatory assignment (same Astellas-side cleanup).

• Effective 2020-12-15 / recorded 2024-12-05 — Reel 069516/0433

  • Conveyance: Change of Address
  • Assignor: Medivation Prostate Therapeutics LLC
  • Assignee: Medivation Prostate Therapeutics LLC (New York address)
  • Correspondent: not determinable
  • Context: Administrative address update only — owner unchanged.

• Effective 2021-02-09 / recorded 2024-12-05 — Reel 069516/0427

  • Conveyance: Change of Address
  • Assignor: Medivation Prostate Therapeutics LLC
  • Assignee: Medivation Prostate Therapeutics LLC (California address)
  • Correspondent: not determinable
  • Context: Administrative address update only.

• Effective 2023-03-07 / recorded 2023-04-19 — Reel 063980/0526

  • Conveyance: Change of Address
  • Assignor: Medivation Prostate Therapeutics LLC
  • Assignee: Medivation Prostate Therapeutics LLC (New York)
  • Correspondent: not determinable
  • Context: Administrative address update only.

• Effective 2023-03-07 / recorded 2023-06-28 — Reel 064149/0149

  • Conveyance: Correction of Names in Coversheet
  • Assignor: Medivation Prostate Therapeutics LLC
  • Assignee: Medivation Prostate Therapeutics LLC
  • Correspondent: not determinable
  • Context: Clerical correction only — fixes the named owner on the coversheet.

Bottom line on the record: every post-issuance/post-2016 entry is a Change of Name, Change of Address, Correction of Names, or Confirmatory Assignment. There is no assignment of the patent to any third party, no security agreement, no license recordation, and no transfer to a licensing entity.

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Timeline diagram

timeline
    title Ownership of US 12161628
    2015 : Priority provisional applications filed
    2016 : Inventors assign to Medivation
         : Pfizer announces Medivation acquisition
    2017 : Medivation Inc renamed Medivation LLC
         : Astellas confirmatory assignment recorded
    2019 : Second Astellas confirmatory assignment
    2022 : Continuation application filed
    2024 : Patent issued on Dec 10
         : Curative assignments recorded on Dec 5
    2025 : First infringement suits filed in January

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NPE / troll-pattern signals

1. Shell-entity transfer — NOT PRESENT. The only Inc.→LLC event is reel 069516/0437, recorded as a Change of Name with effective date 2017-08-25 — an internal corporate renaming, not a sale to a licensing vehicle. The assignee's recorded address is 66 Hudson Boulevard East, New York, NY 10001-2192, which is Pfizer's corporate headquarters, not a registered-agent service address. No products-absent shell is in the chain.

2. Known asserter in the chain — NOT PRESENT. No assignee matches any public NPE list (Acacia, Marathon, Intellectual Ventures, IPNav, Wi-LAN, Conversant/Mosaid, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Erich Spangenberg entities, etc.). Assignees are Astellas Pharma Inc. and Medivation Prostate Therapeutics LLC (a Pfizer subsidiary) — both operating pharmaceutical companies.

3. Repeat correspondent across the chain — UNCLEAR / NOT CONFIRMED. The recording dates cluster tightly (reels 069495/0311, 069495/0448, and 069516/0398, /0427, /0433, /0435, /0437 all recorded 2024-12-05), strongly implying a single firm filed the whole batch. That is a hallmark of either (a) a large law firm's litigation-prep docketing team or (b) an NPE's assembly counsel — the pattern alone does not distinguish them. Because no correspondent name is exposed in the available record, I make no finding here. Do not treat the clustering as an NPE tell without the recorded attorney/firm.

4. Cascading transfers — NOT PRESENT. There are no consecutive assignments through chained LLCs. The 2024 batch is curative cleanup of pre-existing ownership (name change, address changes, confirmatory assignments, coversheet correction) — not a sequence of transfers creating new owners.

5. Pre-litigation transfer — PRESENT, BUT BENIGN. The batch recordation on 2024-12-05 (reels 069516/xxxx, 069495/xxxx) falls ~6 weeks before the first infringement suit (3:25-cv-00578, filed 2025-01-16) and 5 days before grant (2024-12-10). However, these recordings do not transfer the patent to a new asserting entity — they confirm the pre-existing Astellas/Pfizer ownership. This is a "clean standing record" housekeeping move by an operating owner, not a pre-litigation assignment to an NPE set up to control venue/standing. Signal present in timing; not indicative of NPE behavior.

6. Bankruptcy fire-sale — NOT PRESENT. No Chapter 7/11 event; no distressed entity in the chain. The Medivation asset was sold via a competitive $14B M&A auction to Pfizer, not a bankruptcy sale.

7. Privateering — NOT PRESENT. The patent never left the Astellas/Pfizer corporate family. Both owners assert it in their own names (see the litigation record: Astellas Pharma Inc. et al. v. Hikma Pharmaceuticals USA Inc., 3:25-cv-00578, and the parallel actions against Zydus, Haimen/SinoTherapeutics, and Ascent). This is direct operating-company enforcement, the opposite of privateering.

8. Defensive aggregator — NOT PRESENT. The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN.

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Verdict

Operating-company assertion.

The chain runs inventors → Medivation Prostate Therapeutics (reel 069495/0311, executed Feb 2016) → a Change of Name to Medivation Prostate Therapeutics LLC (reel 069516/0437, effective 2017-08-25, a Pfizer subsidiary at Pfizer's HQ address) with Astellas Pharma Inc. as co-owner via confirmatory assignments (reels 069516/0398 and 069516/0435). Every recorded post-2016 event is a name change, address change, correction, or confirmatory assignment — there is no third-party transfer, no licensing shell, and no known asserter in the chain. The current owners ship the commercial product (XTANDI®) and are suing generic ANDA filers — i.e., actual competitors — which is the textbook definition of legitimate operating-company patent enforcement, not NPE activity.

The one timing curiosity worth monitoring — but not an NPE signal — is that a batch of curative assignments was recorded on 2024-12-05, within ~6 weeks of the first January 2025 infringement suits. That is consistent with preparing a clean chain-of-title record for litigation while remaining firmly inside the operating-company model.

Verification link: https://assignmentcenter.uspto.gov/ (search US 12,161,628), mirrored at https://assignment.uspto.gov/patent/index.html.

Analysis of Prior Art Cited in U.S. Patent 12,161,628

This analysis examines the patent references cited during the prosecution of U.S. Patent 12,161,628 to determine their relevance and potential to anticipate the patent's claims under 35 U.S.C. § 102. The core of the invention is Claim 1, which details a method for treating prostate cancer by co-administering a 240 mg daily dose of enzalutamide to a patient who is also being treated with rifampin.

For a prior art reference to anticipate Claim 1, it must expressly or inherently disclose every element of the claim in a single document. The key elements are:

1. A method of treating prostate cancer.
2. The patient is administered rifampin.
3. Co-administration of enzalutamide.
4. A specific daily dose of 240 mg of enzalutamide.

The patent's "Patent Citations" section lists two references, which are analyzed below.

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1. WO2017027660A1: Combination therapy with apalutamide

• Full Citation: WO2017027660A1. "Combination therapy with apalutamide." Assignee: Medivation Technologies, Inc. Publication Date: February 16, 2017. Filing Date: August 11, 2016.
• Brief Description: This patent application describes dosage regimens for co-administering apalutamide (also known as ARN-509), an androgen receptor inhibitor, with strong CYP3A4 inducers like rifampin. It notes that co-administration of rifampin with apalutamide decreases the plasma concentration of apalutamide. To compensate for this drug-drug interaction, the application proposes increasing the daily dose of apalutamide from its standard 240 mg/day to a higher dose, such as 300 mg/day or 360 mg/day. The invention is aimed at treating cancers, including prostate cancer.
• Anticipation Analysis (Claim 1): This reference does not anticipate Claim 1 of US 12,161,628. While it teaches the treatment of prostate cancer and the co-administration of a drug (apalutamide) with rifampin, and it recognizes the need for a dosage increase due to CYP3A4 induction, it fails to meet key requirements of Claim 1.
  • Element 3 (Enzalutamide): The reference discloses apalutamide, not enzalutamide. Although both are androgen receptor inhibitors, they are distinct chemical compounds.
  • Element 4 (240 mg dose): The reference teaches increasing the dose of apalutamide from 240 mg/day to a higher dose (e.g., 360 mg/day). In contrast, the '628 patent claims an increased dose of enzalutamide to 240 mg/day (from a standard 160 mg/day). Therefore, WO2017027660A1 does not disclose the specific 240 mg daily dose for enzalutamide.

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2. US20180228790A1: Combination Therapy with Apalutamide

• Full Citation: US20180228790A1. "Combination Therapy with Apalutamide." Assignee: Medivation Technologies LLC. Publication Date: August 16, 2018. Filing Date: February 9, 2018.
• Brief Description: This document is the U.S. national phase publication of the international application WO2017027660A1, discussed above. Its disclosure is substantively identical. It describes increasing the daily dose of the androgen receptor inhibitor apalutamide when co-administered with a strong CYP3A4 inducer, such as rifampin, to treat prostate cancer. The standard apalutamide dose of 240 mg/day is proposed to be increased to counteract the reduced plasma exposure caused by the inducer.
• Anticipation Analysis (Claim 1): Similar to its international counterpart, this reference does not anticipate Claim 1 of US 12,161,628.
  • Element 3 (Enzalutamide): The document teaches the use of apalutamide, not enzalutamide.
  • Element 4 (240 mg dose): The reference discloses increasing the dose of apalutamide from 240 mg/day and does not teach or suggest a 240 mg dose for enzalutamide.

Conclusion

Neither of the patent references cited during the prosecution of US 12,161,628 anticipates the claimed invention. Both references are directed at a different, albeit functionally similar, compound (apalutamide). Crucially, they do not disclose the specific combination of enzalutamide with rifampin at the claimed 240 mg daily dose. The invention of the '628 patent is based on clinical data specific to enzalutamide, which showed that co-administration with rifampin required an increase from the standard 160 mg dose to 240 mg to maintain therapeutic efficacy. This specific dosage adjustment for this specific drug combination is the novel element not present in the cited prior art.

Obviousness Analysis of U.S. Patent 12,161,628 under 35 U.S.C. § 103

This analysis evaluates whether the claimed invention in U.S. Patent 12,161,628 would have been obvious to a person having ordinary skill in the art (PHOSITA) at the time the invention was made. The standard for obviousness is whether the differences between the claimed invention and the prior art are such that the subject matter as a whole would have been obvious to a PHOSITA.

A PHOSITA in this context would be a clinical pharmacologist or medical oncologist with experience in prostate cancer therapeutics, pharmacokinetics, and drug-drug interactions, particularly those involving the cytochrome P450 enzyme system.

Claim at Issue

The analysis focuses on independent Claim 1, which recites:

• Claim 1: A method of treating prostate cancer in a patient to whom rifampin is administered, comprising co-administering to the patient a daily dose of 240 mg enzalutamide.

The dependent claims (2-6) narrow the type of prostate cancer and are therefore rendered obvious if Claim 1 is obvious.

Proposed Combination of Prior Art

A strong case for obviousness can be made by combining the knowledge of enzalutamide's standard clinical use with the teachings of WO2017027660A1 (hereafter '660).

1. Primary Reference: General knowledge in the art regarding enzalutamide (marketed as XTANDI®). A PHOSITA would have known:

   • Enzalutamide is an androgen receptor inhibitor approved for treating prostate cancer.
   • The standard, FDA-approved daily dose of enzalutamide is 160 mg.
   • Enzalutamide is primarily metabolized by CYP2C8 and CYP3A4. Strong inducers of these enzymes are known to affect the plasma concentration of drugs they metabolize.

2. Secondary Reference: WO2017027660A1, which teaches a "Combination therapy with apalutamide."

Analysis of the Combination

The '660 reference does not anticipate the claims because it deals with apalutamide, not enzalutamide. However, its teachings provide a clear roadmap that would have led a PHOSITA to the invention of the '628 patent with a reasonable expectation of success.

1. Motivation to Combine

A PHOSITA would have been motivated to combine the general knowledge of enzalutamide with the teachings of '660 for several reasons:

• Same Drug Class, Same Problem: The '660 reference addresses the precise problem of a strong CYP3A4 inducer (rifampin) reducing the plasma concentration of a second-generation androgen receptor inhibitor (apalutamide). A PHOSITA would have immediately recognized that enzalutamide, being in the same therapeutic and structural class and metabolized by CYP3A4, would almost certainly face the same issue when co-administered with rifampin. The '660 reference explicitly identifies a known problem and presents a solution.

• Explicit Solution Taught: The '660 reference teaches that the solution to this drug-drug interaction is to increase the daily dose of the androgen receptor inhibitor to compensate for the decreased exposure. This provides a direct suggestion to a PHOSITA facing the same problem with enzalutamide.

2. Reasonable Expectation of Success and the Obviousness of the 240 mg Dose

The most critical element of the analysis is whether a PHOSITA would have arrived at the specific dose of 240 mg. The '660 reference provides a compelling reason to believe they would have.

• Analogous Dose Escalation: The '660 reference discloses that the standard dose for apalutamide is 240 mg/day. To counteract the effect of rifampin, it proposes increasing the dose to 360 mg/day. This represents a 50% increase in the standard dose (360 is 150% of 240).

• Direct Application to Enzalutamide: A PHOSITA, knowing the standard dose of enzalutamide is 160 mg/day, would be motivated by '660 to attempt a dose escalation of a similar magnitude to solve the same metabolic problem. Applying the same 50% dose increase taught for apalutamide directly to enzalutamide leads precisely to the claimed dose:

  • 160 mg (standard enzalutamide dose) * 1.50 = 240 mg

Therefore, the claimed 240 mg dose is not an arbitrary or unexpected finding. It is the exact figure one arrives at by applying the clear, quantitative teaching from a highly analogous prior art reference to the known standard of care for enzalutamide. The determination of this dose would not have required undue experimentation but would have been a predictable and logical starting point for dose adjustment based on the available art. The patent's own description of a potential dose range of "200-300 mg/day" further supports that this was a matter of routine optimization around a predictable value.

Conclusion

At the time of the invention, a person of ordinary skill in the art would have known the standard 160 mg dose of enzalutamide for treating prostate cancer. Upon reviewing WO2017027660A1, which addresses the identical problem of co-administration with rifampin for the closely related drug apalutamide, the PHOSITA would have been motivated to solve this problem for enzalutamide by increasing its dose. The prior art not only suggested a dose increase but provided a clear quantitative guide—a 50% increase. Applying this 50% increase to enzalutamide's standard 160 mg dose directly yields the claimed 240 mg dose.

For these reasons, Claim 1 of U.S. Patent 12,161,628 would have been obvious under 35 U.S.C. § 103. As dependent claims 2-6 merely specify the type of prostate cancer being treated, they would have been obvious for the same reasons.

Patent Term and Application History for U.S. Patent 12,161,628

This analysis details the application history, related patent family members, and term adjustments for U.S. Patent 12,161,628, culminating in its projected expiration date.

Patent Term Adjustments (PTA) and Extensions (PTE)

• Patent Term Adjustment (PTA): There is no information in the provided patent data indicating a specific number of days granted for Patent Term Adjustment. However, the Google Patents legal status entry notes an "Adjusted expiration" date. Typically, a patent's term is 20 years from its earliest non-provisional filing date. The application for this patent (No. 17/959,350) is a continuation of a series of applications dating back to an international application filed on August 11, 2016, which claims priority from provisional applications in August 2015. The standard 20-year term would end in August 2036. The listed expiration in 2037 suggests a PTA was granted, but the precise calculation is not available in the provided text.
• Patent Term Extension (PTE): There is no indication in the available records that a Patent Term Extension under 35 U.S.C. § 156 (often granted to compensate for regulatory review delays by agencies like the FDA) has been applied for or granted for this patent.

Application and Family History

U.S. Patent 12,161,628 is part of a larger family of applications and patents stemming from two U.S. provisional applications filed in 2015.

• Continuation Applications: The patent is a continuation of a chain of prior U.S. applications.

  • The direct parent application is U.S. Application No. 17/706,788, filed March 29, 2022.
  • This application is itself a continuation of U.S. Application No. 15/751,542, filed February 9, 2018 (now abandoned).
  • This chain ultimately traces back to the international application PCT/US2016/046476, filed on August 11, 2016.

• Divisional Applications: The records do not indicate that any divisional applications have been filed from this patent's application chain.

• Related Family Members: The patent family includes several key international and U.S. publications.

  • Priority Applications: The entire family claims priority to U.S. provisional applications 62/204,281 (filed Aug. 12, 2015) and 62/204,954 (filed Aug. 13, 2015).
  • International Application: WO2017027665A1 is the published international application corresponding to PCT/US2016/046476.
  • U.S. Family Publications:
    • US20180235935A1: Published application from the abandoned parent application 15/751,542.
    • US20230042959A1: The published application corresponding to the application that issued as the '628 patent.

Projected Expiration Date

Based on the information available from the Google Patents legal status data, the projected expiration date for U.S. Patent 12,161,628 is February 23, 2037. This date appears to incorporate a patent term adjustment, extending the term beyond the standard 20 years from the 2016 international filing date.

Defensive Disclosure and Prior Art Generation for U.S. Patent 12,161,628

Publication Date: May 10, 2026
Subject: Derivatives and obvious improvements of combination therapy involving enzalutamide and CYP3A4 inducers.
Purpose: To place into the public domain a series of technical disclosures that anticipate potential future patent claims related to the subject matter of U.S. Patent 12,161,628, thereby rendering them non-novel or obvious under 35 U.S.C. § 102 and § 103.

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Axis 1: Therapeutic Agent & Component Substitution

Derivative 1.1: Dose Adjustment of Enzalutamide with Alternative Strong CYP3A4 Inducers

• Enabling Description: The core principle of U.S. Patent 12,161,628 is the dose increase of enzalutamide (a CYP3A4/2C8 substrate) from its standard 160 mg dose to 240 mg to counteract the metabolic induction by rifampin. This principle is extended to other strong CYP3A4 inducers. Based on the known relative induction potential of these agents compared to rifampin, a skilled clinician can determine an adjusted dose of enzalutamide. For example, when co-administered with carbamazepine, which has a similar induction strength to rifampin, a daily dose of 240 mg of enzalutamide is administered. For phenytoin or phenobarbital, which can also be strong inducers, a dose titration starting at 200 mg and escalating to 240 mg based on serum PSA levels and patient tolerance is implemented. This method is applicable to any condition requiring treatment with enzalutamide in a patient who must take a strong CYP3A4 inducer for a co-morbidity such as epilepsy or other infections.

graph TD
    A[Patient with Prostate Cancer on Standard 160mg Enzalutamide] --> B{Initiation of Strong CYP3A4 Inducer for Co-morbidity};
    B --> C1[Inducer: Carbamazepine];
    B --> C2[Inducer: Phenytoin];
    B --> C3[Inducer: St. John's Wort];
    C1 --> D1[Increase Enzalutamide Dose to 240mg/day];
    C2 --> D2[Titrate Enzalutamide Dose from 200mg to 240mg/day];
    C3 --> D3[Increase Enzalutamide Dose to 240mg/day];
    D1 & D2 & D3 --> E[Monitor PSA and Safety];

Derivative 1.2: Use of Deuterated Enzalutamide with a Strong CYP3A4 Inducer

• Enabling Description: A deuterated analog of enzalutamide is developed where one or more hydrogen atoms are replaced by deuterium, specifically at metabolically active sites. This substitution can reduce the rate of metabolism by CYP3A4 and CYP2C8, leading to a longer half-life and altered pharmacokinetic profile. When a patient treated with this deuterated enzalutamide (e.g., standard dose of 120 mg/day) is also administered rifampin, the required dose increase is proportionally smaller than that for standard enzalutamide. A clinical protocol would increase the deuterated enzalutamide dose by 50%, to 180 mg/day, to maintain therapeutic exposure, mirroring the proportional adjustment logic of the parent invention.

sequenceDiagram
    participant P as Patient
    participant D as Deuterated Enzalutamide (120mg)
    participant R as Rifampin
    participant M as Metabolic Pathway (CYP3A4)

    P->>D: Administer standard dose
    loop Treatment Period 1
        D->>M: Slower metabolism (due to D-substitution)
        M->>P: Stable therapeutic concentration
    end
    P->>R: Administer Rifampin
    R->>M: Induce CYP3A4 activity
    loop Treatment Period 2
        D->>M: Increased rate of metabolism
        M->>P: Sub-therapeutic concentration
    end
    Note right of P: Dose Adjustment Needed
    P->>D: Administer adjusted dose (180mg)
    loop Treatment Period 3
        D->>M: Increased metabolism counteracted by higher dose
        M->>P: Restore therapeutic concentration
    end

---

Axis 2: Dosing & Patient Population Parameter Expansion

Derivative 2.1: Genotype-Guided Dosing for CYP2C8/CYP3A4 Polymorphisms

• Enabling Description: The metabolism of enzalutamide is mediated by both CYP3A4 and CYP2C8. Genetic polymorphisms in these enzymes affect a patient's metabolic capacity. This disclosure describes a method wherein patients are genotyped for CYP2C8 (e.g., for the *3 allele, a poor metabolizer) and/or CYP3A4 (e.g., for the *22 allele) prior to treatment. When a strong CYP3A4 inducer like rifampin is co-administered, the enzalutamide dose is adjusted based on this genetic profile. For a normal metabolizer, the dose is increased to 240 mg as per the base invention. For a CYP2C8 poor metabolizer, whose clearance of enzalutamide is already reduced, the dose increase is attenuated to 200 mg/day to avoid excessive exposure and toxicity. Conversely, an ultra-rapid metabolizer might require a dose of 280-320 mg/day.

flowchart TD
    subgraph Pre-Treatment
        A[Patient requiring Enzalutamide + Rifampin] --> B(Genotype for CYP2C8 & CYP3A4);
    end
    subgraph Dosing Algorithm
        B --> C{Metabolizer Status};
        C -- CYP2C8 Poor Metabolizer --> D[Adjust Enzalutamide Dose to 200mg/day];
        C -- Normal Metabolizer --> E[Adjust Enzalutamide Dose to 240mg/day];
        C -- Ultra-Rapid Metabolizer --> F[Adjust Enzalutamide Dose to 280mg/day];
    end
    subgraph Monitoring
        D --> G(Monitor for Toxicity);
        E --> H(Monitor for Efficacy & Safety);
        F --> I(Monitor for Efficacy);
    end

Derivative 2.2: Dosing Based on Therapeutic Drug Monitoring (TDM)

• Enabling Description: Rather than a fixed 240 mg dose, this method employs a TDM-based approach. After a patient on enzalutamide starts rifampin, the enzalutamide dose is initially increased to 200 mg/day. A trough plasma concentration (Cmin) of enzalutamide and its active metabolite (N-desmethyl enzalutamide) is measured after 7-14 days. The dose is then titrated to achieve a target Cmin range known to be associated with clinical efficacy (e.g., 8-15 µg/mL for the combined active moiety). The dose may be adjusted up to 320 mg/day or down to 180 mg/day based on the TDM results and individual patient tolerance, creating a personalized, exposure-matched therapy.

stateDiagram-v2
    [*] --> InitialDose: Patient starts Rifampin
    InitialDose: Enzalutamide set to 200mg/day
    InitialDose --> MeasureTrough: After 7-14 days

    MeasureTrough --> EvaluateTrough
    state EvaluateTrough {
        [*] --> Cmin_Low: Trough < 8 µg/mL
        Cmin_Low --> IncreaseDose: Increase dose to 240mg
        [*] --> Cmin_Target: Trough 8-15 µg/mL
        Cmin_Target --> MaintainDose: Continue current dose
        [*] --> Cmin_High: Trough > 15 µg/mL
        Cmin_High --> DecreaseDose: Decrease dose to 180mg
    }

    IncreaseDose --> MeasureTrough
    MaintainDose --> Stable: Monitor monthly
    DecreaseDose --> MeasureTrough
    Stable --> [*]

---

Axis 3: Cross-Domain Application

Derivative 3.1: Application in HIV Management

• Enabling Description: Patients with HIV are often treated with protease inhibitors (e.g., darunavir, atazanavir), which are potent CYP3A4 substrates. If such a patient contracts tuberculosis (TB), they require treatment with rifampin, a cornerstone of anti-TB therapy. Co-administration of rifampin drastically reduces protease inhibitor concentrations, leading to virologic failure. This disclosure applies the dose-escalation principle: the daily dose of the protease inhibitor is increased by 50-100% (e.g., darunavir/cobicistat dose is modified or boosted differently) to counteract the induction by rifampin. The specific adjustment is guided by TDM to maintain effective antiretroviral activity while monitoring for liver toxicity.

graph TD
    A[Patient with HIV on Protease Inhibitor (CYP3A4 Substrate)] --> B{Diagnosed with Tuberculosis};
    B --> C[Initiate Rifampin-based TB Therapy];
    C --> D{Drug-Drug Interaction: Reduced PI Exposure};
    D --> E[Risk of HIV Virologic Failure];
    E --> F[Action: Increase Protease Inhibitor Dose by 50-100%];
    F --> G[Implement Therapeutic Drug Monitoring (TDM)];
    G --> H[Maintain HIV Suppression & Treat TB];

Derivative 3.2: Application in Organ Transplantation

• Enabling Description: Organ transplant recipients rely on lifelong immunosuppression with calcineurin inhibitors like tacrolimus or cyclosporine. These drugs are narrow therapeutic index CYP3A4 substrates. If a transplant patient develops a seizure disorder requiring treatment with a strong inducer like carbamazepine or phenytoin, their immunosuppressant levels can fall precipitously, risking acute organ rejection. This method describes increasing the daily tacrolimus dose by 200-300% upon initiation of the enzyme-inducing anti-epileptic. Dosing is aggressively managed using frequent trough level monitoring to keep the immunosuppressant within its target therapeutic range.

sequenceDiagram
    participant P as Transplant Patient
    participant T as Tacrolimus (CYP3A4 Substrate)
    participant C as Carbamazepine (CYP3A4 Inducer)
    participant O as Transplanted Organ

    P->>T: Takes stable daily dose
    T->>O: Maintains immunosuppression (No Rejection)
    P->>C: Starts Carbamazepine for seizures
    C-->>T: Induces rapid metabolism of Tacrolimus
    T-->>O: Levels drop, risk of Acute Rejection
    P->>T: Administer 3x increased daily dose
    T->>O: Therapeutic levels restored, immunosuppression maintained

Derivative 3.3: Application in Oncology with Targeted Therapies

• Enabling Description: Many oral targeted cancer therapies, such as tyrosine kinase inhibitors (TKIs) (e.g., erlotinib, pazopanib), are CYP3A4 substrates. If a patient with lung cancer on erlotinib develops an infection requiring treatment with rifampin, erlotinib exposure can decrease by over 60%, leading to loss of anti-tumor effect. This method involves increasing the erlotinib dose from 150 mg/day to 300 mg/day or higher when co-administered with rifampin, with careful monitoring for side effects like rash and diarrhea, to maintain the necessary plasma concentration for tumor control.

flowchart LR
    A[Cancer Patient on TKI (e.g. Erlotinib 150mg)] --> B(Concurrent Infection);
    B --> C{Requires Rifampin};
    C --> D(CYP3A4 Induction);
    D --> E(Sub-therapeutic TKI Levels);
    E --> F(Risk of Tumor Progression);
    F --> G(Intervention: Increase TKI Dose to 300mg);
    G --> H(Monitor for Efficacy & Toxicity);

---

Axis 4: Integration with Emerging Tech

Derivative 4.1: AI-Driven Personalized Dosing Platform

• Enabling Description: A machine learning model is developed, trained on real-world data (RWD) encompassing patient genomics (CYP2C8/3A4 status), co-medications, liver function tests, body weight, and reported outcomes. When a patient is prescribed enzalutamide and rifampin, the platform integrates their specific data to predict an optimal starting dose (e.g., 220 mg, 240 mg, or 260 mg). The system then uses real-time data from an IoT wearable (monitoring activity levels, sleep patterns for signs of fatigue) and patient-reported outcomes via a mobile app to suggest dose adjustments, creating a dynamic, closed-loop therapeutic system.

classDiagram
    class Patient {
        +genomicData
        +coMedications
        +labValues
        +wearableData
        +reportedOutcomes
    }
    class AI_DosingEngine {
        -ML_Model
        +predictOptimalDose()
        +suggestDoseAdjustment()
    }
    class IoTSensor {
        +activityLevel
        +sleepData
        +streamData()
    }
    class ClinicianDashboard {
        +viewPredictions()
        +approveAdjustments()
    }
    Patient "1" -- "1" AI_DosingEngine : provides data
    Patient "1" -- "1" IoTSensor : wears
    IoTSensor --|> AI_DosingEngine : streams data
    AI_DosingEngine --|> ClinicianDashboard : displays recommendations

Derivative 4.2: Blockchain for Treatment Adherence and Verification

• Enabling Description: A private blockchain ledger is used to track the prescription and administration of high-cost, high-interaction drug combinations like enzalutamide and rifampin. When a clinician prescribes the adjusted 240 mg dose, the order is recorded as an immutable transaction on the blockchain. The specialty pharmacy dispensing the drug records the fulfillment. The patient's smart pill bottle (an IoT device) records each time the dose is taken. This creates an auditable trail for payers to verify adherence for value-based care contracts and for researchers to collect high-fidelity RWD for pharmacovigilance.

flowchart TD
    A[Clinician Prescribes 240mg Enzalutamide] --> B(Create Transaction on Blockchain);
    B --> C[Pharmacy Dispenses & Updates Ledger];
    C --> D[Patient Takes Dose from IoT Pill Bottle];
    D --> E(Pill Bottle Writes to Ledger);
    E --> F{Data is Immutable & Auditable};
    F --> G[Payers for Value-Based Reimbursement];
    F --> H[Researchers for Pharmacovigilance];

---

Axis 5: The "Inverse" or Failure Mode

Derivative 5.1: Toxicity-Based De-Escalation Protocol

• Enabling Description: This method describes a protocol for managing adverse events in patients on the 240 mg adjusted dose of enzalutamide with rifampin. If a patient develops a pre-defined toxicity, such as Grade 3 fatigue, severe hypertension, or a seizure, the enzalutamide dose is immediately reduced to the standard 160 mg/day. TDM is performed to ensure the level does not fall below a minimal therapeutic threshold. If the toxicity resolves to Grade 1 or less within 14 days, the dose can be re-escalated to 200 mg/day. This protocol prioritizes patient safety over maintaining maximum theoretical exposure in the event of severe side effects.

stateDiagram-v2
    OnTreatment: At 240mg Dose
    [*] --> OnTreatment

    OnTreatment --> ToxicityEvent: Grade >= 3 Adverse Event
    ToxicityEvent --> DoseReduction: Reduce Dose to 160mg
    DoseReduction --> Monitoring: Monitor for 14 days
    Monitoring --> Resolved: Toxicity <= Grade 1
    Monitoring --> Persistent: Toxicity > Grade 1
    Resolved --> ReEscalate: Increase Dose to 200mg
    Persistent --> StopTherapy: Discontinue Enzalutamide
    ReEscalate --> OnTreatment

Derivative 5.2: Use in Neoadjuvant (Pre-Surgery) Setting with Intermittent Dosing

• Enabling Description: For patients with high-risk localized prostate cancer, a neoadjuvant (pre-prostatectomy) regimen is described. The patient receives enzalutamide at the adjusted 240 mg dose while on rifampin (for a concurrent condition) for a fixed period of 3-6 months. The goal is to shrink the tumor and reduce micrometastatic disease before surgery. The therapy is intermittent and not for chronic treatment of metastatic disease. This application represents a "limited-functionality" mode, as the goal is short-term tumor response rather than long-term disease suppression. This method reduces the total duration of drug exposure and potential for long-term side effects.

graph TD
    A[High-Risk Localized Prostate Cancer] --> B(Concurrent Condition Requiring Rifampin);
    B --> C[Initiate Neoadjuvant Therapy];
    C --> D[3-6 month course of Enzalutamide 240mg/day];
    D --> E[Goal: Tumor Volume Reduction];
    E --> F[Definitive Surgery (Prostatectomy)];
    F --> G[End of Combination Therapy];

---

Combination Prior Art with Open-Source Standards

1. Combination with OMOP Common Data Model: The dosing algorithm described in Derivative 2.1 (Genotype-Guided Dosing) is implemented within a Real-World Evidence (RWE) study. Patient data from electronic health records (EHRs) are ETL'd into the Observational Medical Outcomes Partnership (OMOP) Common Data Model. A cohort of patients on enzalutamide and strong CYP3A4 inducers is identified. The outcomes (PSA response, adverse events) for patients dosed according to a genotype-guided algorithm versus a standard fixed-dose adjustment are compared, demonstrating the clinical utility of the disclosed method within a standardized, open-source data framework for observational research.

2. Combination with FHIR (Fast Healthcare Interoperability Resources): The AI-driven dosing platform from Derivative 4.1 is integrated into a clinician's EHR workflow using FHIR APIs. The AI engine is encapsulated as a Clinical Decision Support (CDS) Hook. When a physician prescribes enzalutamide for a patient already on rifampin, the EHR triggers the CDS Hook. The hook service reads relevant patient data (labs, meds) via FHIR resources (e.g., Patient, MedicationRequest, Observation) and returns a "card" to the EHR interface recommending the specific 240 mg dose, along with links to the supporting evidence. This demonstrates the invention's implementation using open, interoperable health data standards.

3. Combination with CDISC (Clinical Data Interchange Standards Consortium): A clinical trial protocol is designed to validate the TDM approach from Derivative 2.2. The protocol specifies that all pharmacokinetic and clinical outcome data must be collected and structured according to CDISC standards, specifically the Study Data Tabulation Model (SDTM) for raw data and the Analysis Data Model (ADaM) for analysis datasets. This ensures the data are ready for regulatory submission (e.g., to the FDA) and can be easily aggregated with other trial data for meta-analyses, demonstrating the invention's application within the open standards governing clinical research.