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.