US 8377903

Here's a concise summary of US Patent 8377903:

Title: Cladribine regimen for treating multiple sclerosis
Assignee: Merck Serono SA
Inventors: Giampiero De luca, Arnaud Ythier, Alain Munafo, Maria Lopez-Bresnahan
Filing Date: April 23, 2010
Issue Date: February 19, 2013

Abstract:
The patent describes the use of Cladribine for preparing a pharmaceutical formulation to treat multiple sclerosis, specifically relapsing-remitting multiple sclerosis or early secondary progressive multiple sclerosis. The formulation is intended for oral administration, and the regimen allows for re-treatments.

Plain-Language Overview of Independent Claims:

It's important to note that as of January 29, 2026, the Delaware District Court entered final judgment invalidating claims across U.S. Patent No. 8,377,903 as obvious, specifically including claims 17, 19, 20, and 22–27. This ruling was driven by a precedential Federal Circuit decision. A similar outcome was seen on February 2, 2026, in the Merck vs. Apotex case, where claims 17, 19, 20, and 22–27 of the '903 patent were also declared invalid as obvious. The Federal Circuit affirmed the unpatentability ruling for US8377903B2 on October 30, 2025, in a case brought by Merck Serono SA against TWI Pharmaceuticals Inc., rendering the patent invalid and unenforceable.

• Independent Claim 1: This claim outlines a method for treating relapsing-remitting multiple sclerosis or early secondary progressive multiple sclerosis. It involves orally administering a cladribine formulation in a structured four-step sequence:

  1. Induction Period: For approximately 2 to 4 months, the cladribine formulation is taken orally, with the total dose of cladribine reaching between about 1.7 mg/kg and 3.5 mg/kg by the end of this period.
  2. First Cladribine-Free Period: No cladribine is administered for approximately 8 to 10 months.
  3. Maintenance Period: For approximately 2 to 4 months, the cladribine formulation is orally administered again, but the total dose of cladribine during this period is lower than that given during the initial induction period.
  4. Second Cladribine-Free Period: No cladribine is administered during this period.

• Independent Claim 17: This claim is similar to Claim 1, also detailing a method for treating relapsing-remitting multiple sclerosis or early secondary progressive multiple sclerosis with an oral cladribine formulation following a sequential regimen:

  1. Induction Period: For approximately 2 to 4 months, the cladribine formulation is taken orally, with the total dose of cladribine reaching between about 1.7 mg/kg and 3.5 mg/kg by the end of this period.
  2. First Cladribine-Free Period: No cladribine is administered for approximately 8 to 10 months.
  3. Maintenance Period: For approximately 2 to 4 months, the cladribine formulation is orally administered, and specifically, the total dose of cladribine reached by the end of this maintenance period is about 1.7 mg/kg.
  4. Second Cladribine-Free Period: No cladribine is administered during this period.

U.S. Patent 8,377,903 has been involved in several significant litigation cases, primarily concerning its validity related to cladribine dosing regimens for treating multiple sclerosis.

Here's a summary of known litigation:

• Case 1: Merck Serono SA v. TWI Pharmaceuticals Inc.

  • Plaintiff(s): Merck Serono SA
  • Defendant(s): TWI Pharmaceuticals Inc.
  • Jurisdiction: United States Court of Appeals for the Federal Circuit (CAFC), appealing a decision from a lower tribunal (likely a district court or PTAB).
  • Case Number: 25-1464
  • Filing Date: February 19, 2025
  • Outcome/Current Status: The Federal Circuit affirmed the lower tribunal's ruling of unpatentability for US8377903B2 on October 30, 2025. This means the patent is invalid and unenforceable. Merck Serono's options for further appeal are limited.

• Case 2: Merck KGaA v. Hopewell Pharma Ventures, Inc.

  • Plaintiff(s): Merck KGaA
  • Defendant(s): Hopewell Pharma Ventures, Inc.
  • Jurisdiction: Delaware District Court, affirmed by the Federal Circuit.
  • Case Number: 1:22-cv-01365 (D. Del.)
  • Filing Date: The duration of the case was from October 2022 to January 2026.
  • Outcome/Current Status: The Delaware District Court entered final judgment on January 29, 2026, in favor of Hopewell Pharma Ventures, Inc., invalidating claims of US8377903 (among other patents) as obvious. This ruling was driven by a precedential Federal Circuit decision.

• Case 3: Merck v. Apotex

  • Plaintiff(s): Merck (likely Merck KGaA or Merck Serono SA)
  • Defendant(s): Apotex Inc. and Apotex Corp.
  • Jurisdiction: Federal Circuit (as the controlling decision from Merck Serono v. Hopewell was cited, indicating a federal court ruling).
  • Filing Date: Not explicitly stated, but the outcome was reported on February 2, 2026.
  • Outcome/Current Status: The court entered judgment entirely in favor of Apotex, declaring claims 17, 19, 20, and 22–27 of the '903 patent (among others) invalid as obvious. All of Merck's infringement claims were dismissed.

It is important to note that while some sources initially indicated "no publicly documented litigation specific to U.S. Patent 8,377,903", more recent and specific search results from PatSnap and Unified Patents clearly detail these cases, providing more current and accurate information.

Proceedings overview

There are two active Inter Partes Review (IPR) proceedings filed against US patent 8377903. Both IPR2023-00050 and IPR2023-00481 are currently in the "Final Written Decision" stage, indicating that institution was granted and the PTAB has issued its final decision. For a defendant, the current posture means that two challenges to the patent have proceeded to a final decision, the outcome of which needs to be carefully examined to understand the remaining enforceability of the patent claims.

IPR2023-00050 — {Petitioner} v. {Patent Owner}

• Type: Inter Partes Review
• Filed: I do not have the exact filing date for IPR2023-00050.
• Status: Final Written Decision
• Judge panel: I do not have the judge panel information for this proceeding.
• Petition grounds: I do not have information on the specific claims, prior art, or statutory basis (§ 102 / § 103 / § 112) for the petition.
• Institution decision: I do not have information on the institution decision for this proceeding.
• Final Written Decision (if issued): I do not have the specific claim-level verdict or the panel's reasoning.
• Settlement / termination: I do not have information on any settlement or termination for this proceeding.
• Appeal: I do not have information on any appeal to the Federal Circuit for this proceeding.
• Defensive value: Without the details of the final written decision, it's not possible to definitively state the defensive value. However, the existence of a final written decision suggests that some claims may have been challenged and potentially invalidated, which could be beneficial for a defendant.

IPR2023-00481 — {Petitioner} v. {Patent Owner}

• Type: Inter Partes Review
• Filed: I do not have the exact filing date for IPR2023-00481.
• Status: Final Written Decision
• Judge panel: I do not have the judge panel information for this proceeding.
• Petition grounds: I do not have information on the specific claims, prior art, or statutory basis (§ 102 / § 103 / § 112) for the petition.
• Institution decision: I do not have information on the institution decision for this proceeding.
• Final Written Decision (if issued): I do not have the specific claim-level verdict or the panel's reasoning.
• Settlement / termination: I do not have information on any settlement or termination for this proceeding.
• Appeal: I do not have information on any appeal to the Federal Circuit for this proceeding.
• Defensive value: Similar to IPR2023-00050, without the details of the final written decision, it's not possible to definitively state the defensive value. The issuance of a final written decision indicates that a challenge was heard and a determination made, which could impact the patent's strength.

Strategic summary

Based on the provided information, both IPR2023-00050 and IPR2023-00481 have reached the "Final Written Decision" stage. However, the specific outcomes at a claim-level are not available in the provided patent text or the USPTO ODP API result snippet. Therefore, it is currently unknown which claims of US8377903 are CANCELED, SUSTAINED, or UNTESTED through these IPR proceedings. Without the detailed FWDs, it's impossible to assess the estoppel landscape or identify any patterns in petitioner behavior or patent owner's appeal aggressiveness.

Recommended next steps

To understand the full defensive value, it is crucial to obtain and review the Final Written Decisions for IPR2023-00050 and IPR2023-00481. These documents, publicly available on the USPTO PTAB Decisions website, will detail which claims were found unpatentable and the reasons for those decisions. This information is critical for any defendant to evaluate potential infringement theories and available prior-art grounds.

Inventors

• Giampiero De luca (Merck Serono SA)
• Arnaud Ythier (Merck Serono SA)
• Alain Munafo (Merck Serono SA)
• Maria Lopez-Bresnahan (Merck Serono SA)

Original assignee

The original assignee, Merck Serono SA, is a subsidiary of Merck KGaA, a multinational pharmaceutical, chemical, and life sciences company. They do ship products embodying the claims, specifically Mavenclad (cladribine) for multiple sclerosis. Merck Serono SA is currently operating.

Assignment timeline

• 2010-05-05 (executed) / recorded 2010-05-05 — Reel 024629/0878
  • Conveyance: Assignment
  • Assignor: DE LUCA, GIAMPIERO
  • Assignee: LABORATOIRES SERONO SA
  • Correspondent: MCDONNELL, JANET, Laboratoires Serono S.A.
  • Context: Internal reorg
• 2010-05-05 (executed) / recorded 2010-05-05 — Reel 024629/0882
  • Conveyance: Assignment
  • Assignor: LOPEZ-BRESNAHAN, MARIA, YTHIER, ARNAUD, MUNAFO, ALAIN
  • Assignee: MERCK SERONO SA
  • Correspondent: MCDONNELL, JANET, Laboratoires Serono S.A. (This correspondent also appears on reel 024629/0878)
  • Context: Internal reorg
• 2010-05-05 (executed) / recorded 2010-05-05 — Reel 024629/0879
  • Conveyance: Merger
  • Assignor: LABORATOIRES SERONO S.A.
  • Assignee: MERCK SERONO SA
  • Correspondent: MCDONNELL, JANET, Laboratoires Serono S.A. (This correspondent also appears on reel 024629/0878 and 024629/0882)
  • Context: Internal reorg (change of name due to merger)
• 2023-03-20 (executed) / recorded 2023-03-20 — Reel 059952/0970
  • Conveyance: Change of Name
  • Assignor: MERCK SERONO SA
  • Assignee: MERCK SERONO SA
  • Correspondent: JANET M. MCDONNELL, Merck Serono SA. (This correspondent also appears on reel 024629/0878, 024629/0882, and 024629/0879)
  • Context: Change of name only

Timeline diagram

timeline
    title Ownership of US 8377903
    2010 : Filed by Merck Serono SA
         : Inventors assigned to Lab Serono SA
         : Inventors assigned to Merck Serono SA
         : Lab Serono SA merged into Merck Serono SA
    2013 : Issued
    2023 : Merck Serono SA change of name

NPE / troll-pattern signals

1. Shell-entity transfer — not present. All transfers are to or from entities clearly associated with Merck Serono SA.
2. Known asserter in the chain — not present. Merck Serono SA is an operating company.
3. Repeat correspondent across the chain — present. Janet McDonnell (Laboratoires Serono S.A. / Merck Serono SA) is listed as the correspondent on all recorded assignments (Reel 024629/0878, 024629/0882, 024629/0879, and 059952/0970). This indicates consistent internal handling of assignments.
4. Cascading transfers — not present. The initial assignments in 2010 are part of a simultaneous internal reorganization/merger.
5. Pre-litigation transfer — not present. The last assignment (change of name) was in March 2023, while litigation cases were filed starting in October 2022.
6. Bankruptcy fire-sale — not present.
7. Privateering — not present.
8. Defensive aggregator (anti-NPE) — not present.

Verdict

Operating-company assertion. The assignment records (Reel 024629/0878, 024629/0882, 024629/0879, and 059952/0970) consistently show ownership within the Merck Serono SA / Laboratoires Serono S.A. corporate structure, and the litigation summary indicates Merck Serono SA as the plaintiff. This aligns with an operating company asserting its patent rights.

USPTO Assignment Center search: https://assignmentcenter.uspto.gov/patent/index.html

Here's an analysis of the most relevant patent prior art for US Patent 8,377,903, based on the citations listed within the patent text.

Overview of Patent 8,377,903 Claims

The independent claims of US 8,377,903, specifically Claims 1 and 17, define a method for treating relapsing-remitting multiple sclerosis (RRMS) or early secondary progressive multiple sclerosis (SPMS) using an orally administered cladribine formulation. The core inventive step lies in a specific sequential dosing regimen:

• An induction period (2-4 months) with a total cladribine dose of 1.7 mg/kg to 3.5 mg/kg.
• A cladribine-free period (8-10 months).
• A maintenance period (2-4 months) with a total cladribine dose lower than the induction dose (Claim 1) or specifically about 1.7 mg/kg (Claim 17).
• A second cladribine-free period.

This regimen emphasizes oral administration, specific dose ranges, durations for each phase, and the relationship between induction and maintenance doses, with the possibility of re-treatments.

Analysis of Patent Citations

Here are the patent citations listed in US 8,377,903, along with their potential for anticipating the claims under 35 U.S.C. § 102:

1. US 5,506,214 A

   • Full Citation: US 5,506,214 A, "Use of substituted adenine derivatives for treating multiple sclerosis", issued April 9, 1996, to The Scripps Research Institute.
   • Publication/Filing Date: Filed February 3, 1986; Published April 9, 1996.
   • Brief Description: This patent broadly teaches the use of substituted adenine derivatives, including 2-chloro-2'-deoxyadenosine (cladribine), for the treatment of multiple sclerosis. It is also cited in US 8,377,903 for representative oral formulations of 2-CdA.
   • Potential Anticipation (35 U.S.C. § 102): This reference anticipates the general concept of using cladribine to treat multiple sclerosis. While it mentions oral formulations, it does not disclose the specific sequential multi-phase oral dosing regimen—including the defined durations of induction, cladribine-free, and maintenance periods, the specific total dose ranges, and the relationship of a lower maintenance dose to an induction dose—as claimed in US 8,377,903. Therefore, it does not anticipate claims 1-29 in their entirety under 35 U.S.C. § 102.

2. US 4,964,848 A

   • Full Citation: US 4,964,848 A, "Treatment of multiple sclerosis with lymphocytapheresis and chemo-immunosuppression", issued October 23, 1990, to Bloom Philip M.
   • Publication/Filing Date: Filed June 27, 1988; Published October 23, 1990.
   • Brief Description: This patent describes a method for treating multiple sclerosis using lymphocytapheresis in combination with chemo-immunosuppression.
   • Potential Anticipation (35 U.S.C. § 102): This patent does not disclose cladribine or any specific oral cladribine dosing regimen. It pertains to a different treatment approach for multiple sclerosis. Therefore, it does not anticipate any claims of US 8,377,903 under 35 U.S.C. § 102.

3. EP 0 626 853 B1

   • Full Citation: EP 0 626 853 B1, "Use of substituted adenine derivatives for treating multiple sclerosis", issued April 26, 2000, to The Scripps Research Institute.
   • Publication/Filing Date: Filed February 19, 1992; Published April 26, 2000.
   • Brief Description: This European patent is a counterpart to US 5,506,214 A, broadly disclosing the use of substituted adenine derivatives (like cladribine) for treating multiple sclerosis. It is cited in US 8,377,903 as suggesting cladribine's usefulness in MS.
   • Potential Anticipation (35 U.S.C. § 102): Similar to US 5,506,214 A, this patent anticipates the general concept of using cladribine to treat multiple sclerosis. However, it does not explicitly disclose the specific multi-phase oral dosing regimen, including the defined durations, dose relationships, and sequential steps, as claimed in US 8,377,903 (Claims 1-29). Therefore, it does not anticipate claims 1-29 in their entirety under 35 U.S.C. § 102.

4. WO 2004/087101 A2

   • Full Citation: WO 2004/087101 A2, "Oral formulations of cladribine", published October 14, 2004, to Ivax Corporation.
   • Publication/Filing Date: Filed March 28, 2003; Published October 14, 2004.
   • Brief Description: This international patent application specifically describes various oral formulations of cladribine, particularly cyclodextrin formulations. US 8,377,903 explicitly references this patent (WO 2004/087101) for the cladribine cyclodextrin formulation used in its own Example 1.
   • Potential Anticipation (35 U.S.C. § 102): This reference explicitly discloses oral formulations of cladribine, including specific cyclodextrin formulations. Therefore, it anticipates any claim of US 8,377,903 that broadly covers an "oral administration of a formulation comprising cladribine" (e.g., Claims 1, 9, 11, 12, 17, 25, 26, and their dependents). If WO 2004/087101 A2 also explicitly discloses the use of these oral cladribine formulations for treating MS, it would further anticipate that combination. However, it is highly unlikely that WO 2004/087101 A2, primarily focused on formulations, would anticipate the specific sequential multi-phase dosing regimen (induction, cladribine-free, maintenance periods with their specific durations and dose relationships) as defined in Claims 1 and 17.

5. US 2010/0021429 A1

   • Full Citation: US 2010/0021429 A1, "Cladribine regimen for treating multiple sclerosis", published January 28, 2010, to Laboratories Serono Sa.
   • Publication/Filing Date: Filed May 24, 2006; Published January 28, 2010.
   • Brief Description: The abstract and title of this patent application are identical to those of US 8,377,903, describing the oral administration of cladribine for the treatment of multiple sclerosis, including relapsing-remitting multiple sclerosis or early secondary progressive multiple sclerosis, with provisions for re-treatments. This application details the same sequential steps and dose ranges as US 8,377,903.
   • Potential Anticipation (35 U.S.C. § 102): Given the identical abstract and title, and its publication date (January 28, 2010) preceding the filing date of US 8,377,903 (April 23, 2010), this reference would literally anticipate all claims (Claims 1-29) of US 8,377,903 under a strict interpretation of 35 U.S.C. § 102, as it describes the identical invention. However, it is highly probable that US 2010/0021429 A1 is an earlier-published application within the same patent family, sharing a common priority date (December 22, 2004) with US 8,377,903, and by the same inventive entity/assignee. In such a scenario, while it literally discloses the claimed subject matter, it would not typically serve as invalidating prior art under current US patent law due to common ownership/inventorship and proper priority claims.

Most Relevant Prior Art:

For purposes of anticipation under 35 U.S.C. § 102, US 2010/0021429 A1 is the most relevant reference as it literally discloses the entire claimed invention, including the specific sequential oral dosing regimen for cladribine in MS. Following that, WO 2004/087101 A2 is highly relevant for its disclosure of oral cladribine formulations, which forms a fundamental component of the methods claimed in US 8,377,903.

Under 35 U.S.C. § 103, an invention is considered obvious if the differences between the claimed invention and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art (PHOSITA). The analysis involves identifying relevant prior art, determining the differences between the prior art and the claimed invention, and articulating a motivation to combine or modify the prior art to arrive at the claimed invention with a reasonable expectation of success.

The independent claims of US Patent 8,377,903 (Claims 1 and 17) describe a method for treating relapsing-remitting multiple sclerosis (RRMS) or early secondary progressive multiple sclerosis (SPMS) using an orally administered cladribine formulation in a sequential regimen comprising an induction period, a cladribine-free period, a maintenance period, and another cladribine-free period, with specific dose ranges and durations for each period.

Identified Prior Art and Their Teachings:

1. Grieb et al. (1995, Archivum Immunologiae et Therapiae Experimentalis, 43 (5-6), 323-327): This is a highly relevant prior art reference, describing an oral cladribine regimen for RRMS. It disclosed "6 monthly courses of 5 days at a total dose of about 4-5.7 mg/kg" (over 6 months) and included a "single re-treatment of 5 days at a cumulative dose of 0.4-0.66 mg/kg after a cladribine free-period of 3 or 6 months." However, Grieb et al. noted that while side effects were less severe than IV infusion, they were "still present," and the "therapeutic efficacy of the oral regimen above versus the i.v. infusion therapy was questioned."
2. U.S. Pat. No. 5,506,214 and EP 626853B1: These references suggest cladribine's usefulness in treating MS generally.
3. Selby et al. (1998), Romine et al. (1999), Rice et al. (2000), Beutler et al. (1996): These references collectively establish the efficacy of cladribine in treating various forms of MS (including RRMS, SPMS, and chronic progressive MS) via intravenous (IV) or subcutaneous (SC) administration, often in repeated or pulsed regimens.
4. Beutler et al. (1994, 1996): These articles highlight adverse effects (AEs) of cladribine, such as increased incidence of infections or myelosuppression, particularly with higher doses. Beutler et al. (1996) went as far as "excluded the oral route for the treatment of multiple sclerosis with Cladribine" due to the narrow safety margin.
5. WO 2004/087100 and WO 2004/087101: These documents describe representative oral formulations of 2-CdA (cladribine), indicating that oral formulations were known and available.

Differences Between the Claims and the Prior Art:

The key differences between the claimed regimens (Claims 1 and 17) and Grieb et al. (1995) lie primarily in the specific durations of the induction and cladribine-free periods, and the structure and dosage of the maintenance period:

• Induction Period Duration: Claims 1 and 17 specify an induction period of "about 2 months to about 4 months." Grieb et al. describes "6 monthly courses," totaling a 6-month induction.
• Cladribine-Free Period Duration: Claims 1 and 17 specify a cladribine-free period of "about 8 months to about 10 months." Grieb et al. described "3 or 6 months" for this period.
• Maintenance Period Structure and Dose: Claims 1 and 17 define a structured "maintenance period lasting from about 2 months to about 4 months," with the total dose being "lower than the total dose of cladribine reached at the end of the induction period" (Claim 1) or specifically "about 1.7 mg/kg" (Claim 17). Grieb et al. described a "single re-treatment of 5 days" at a very low cumulative dose.

Motivation to Combine/Modify the Prior Art:

The patent itself clearly articulates the problems and desires that would motivate a PHOSITA to combine and modify the existing prior art. The "Summary of the Invention" states, "Therefore, it would be desirable to have a method for treating multiple sclerosis comprising the oral administration of Cladribine that would permit the same or improved effect on MS lesions while decreasing the occurrence and/or severity adverse events. In addition, as MS is a chronic disease, it would be desirable to decrease the occurrence and/or severity adverse events in such a way that re-treatments are possible. A sustained benefit of Cladribine treatment between the treatment periods is also desirable."

A PHOSITA would be motivated to address the limitations of Grieb et al.'s oral cladribine regimen, specifically the "questioned" efficacy and the "still present" side effects, to enable safer and more effective re-treatments for a chronic disease like MS. This motivation would lead a PHOSITA to:

1. Shorten the Induction Period: Knowing cladribine's myelosuppressive effects (Beutler et al.) and the desire to reduce adverse events, a PHOSITA would be motivated to explore shorter initial induction periods (e.g., 2-4 months as claimed, compared to Grieb's 6 months) to minimize early cumulative drug exposure while aiming for an effective initial depletion of lymphocytes. The patent's own Example 1 demonstrates 2-month and 4-month induction periods, indicating these durations were considered viable.
2. Lengthen the Cladribine-Free Periods: To allow for greater immune recovery and further reduce adverse events, a PHOSITA would be motivated to extend the cladribine-free period beyond Grieb's 3 or 6 months to, for example, 8 to 10 months. This would directly address the stated need for reduced adverse effects to allow re-treatments.
3. Optimize Maintenance Dosing and Duration: Given Grieb's questioned efficacy for a single low-dose re-treatment, a PHOSITA would be motivated to explore more robust maintenance regimens that could provide a "sustained benefit" and address the chronic nature of MS. This would involve structuring a maintenance "period" (e.g., 2-4 months) with a total dose that is still lower than the induction dose for safety (as in Claim 1), but potentially higher than Grieb's minimal re-treatment to improve efficacy. For Claim 17's specific maintenance dose of about 1.7 mg/kg, a PHOSITA would be motivated to consider doses known to be effective from other short induction regimens, such as the 2-month induction period total dose of 1.75 mg/kg (effective dose 0.7 mg/kg) used in Group 2 of Example 1.

The selection of specific dose ranges (1.7-3.5 mg/kg for induction) and durations for the various periods, when viewed in light of the prior art (Grieb et al. establishing oral administration and repeated dosing, and other references establishing cladribine's efficacy and side effect profile), represents routine optimization. A PHOSITA would systematically adjust these parameters to achieve an improved balance of efficacy and safety, particularly for a chronic disease requiring re-treatment. The oral formulations described in documents like WO 2004/087101 would be readily available for use in such optimized regimens.

Therefore, a combination of Grieb et al. (1995), which teaches oral cladribine for RRMS with pulsed dosing and re-treatment but notes limitations, in view of the general knowledge of cladribine's efficacy and adverse effects (e.g., Selby et al., Beutler et al., Rice et al.), and the availability of oral formulations (WO 2004/087101), would render the claimed regimens obvious to a PHOSITA. The motivation would be to optimize the oral cladribine regimen to improve efficacy, reduce adverse events, and enable sustained re-treatment for MS patients.