A Study to Evaluate the Effects of Rituximab on Immune Responses in Subjects With Active Rheumatoid Arthritis Receiving Background Methotrexate

Patients were randomized to 2 groups in this study: Group A (active group) and Group B (control group). Patients with active rheumatic arthritis treated with rituximab in combination with methotrexate (Group A) were compared with patients treated with methotrexate alone (Group B).

Group A

Group A patients received rituximab 1000 mg intravenously (IV) on Days 3 and 17 of the 36 week treatment period.

At Day 1 and at Week 24, patients received an intradermal injection of 0.1 mL of C. albicans on the volar surface of the forearm. Forty-eight to 72 hours after each injection, patients were evaluated for a delayed-type hypersensitivity response by measuring the diameter of induration (palpable raised, hardened area of the forearm skin).

At Week 24, patients received a tetanus toxoid adsorbed booster vaccine (1 mg in 0.5 mL) intramuscular (IM) injection in the deltoid muscle. Serum levels of tetanus toxoid titers were obtained at Day 3 immediately prior to the first administration of rituximab, and immediately prior to and 4 weeks after administration of the tetanus toxoid adsorbed vaccine.

At Week 28, patients received an IM injection of the 23-valent pneumococcal polysaccharide vaccine (0.5 mL) in the deltoid muscle. Serum levels for antibodies to 12 pneumococcal serotypes were measured at Day 3 immediately prior to the first administration of rituximab, and immediately prior to and 4 weeks after administration of the pneumococcal vaccine.

At Weeks 32 and 33, patients received subcutaneous (SC) keyhole limpet hemocyanin 1 mg. Serum anti-keyhole limpet hemocyanin antibody levels were measured at Day 3 immediately prior to the first administration of rituximab, and immediately prior to and 4 weeks after the first administration of keyhole limpet hemocyanin.

Samples were obtained for the determination of serum rituximab concentration (pharmacokinetics), peripheral blood CD19 counts (pharmacodynamics), and the presence of human anti-chimeric antibodies from all patients in Group A.

Group A patients completed the treatment period at Week 36 and, if qualified, had the option of entering the optional extension re-treatment period. Patients who did not qualify for or who did not choose to receive the optional extension re-treatment entered the approximately 1-year safety follow-up period. After the safety follow-up period, patients who remained peripherally CD19-positive B-cell depleted entered the B-cell follow-up period where they were followed every 12 weeks until their peripheral CD19-positive B cells returned to baseline values or the lower limit of normal, whichever was lower.

Group B

Because the immune response to vaccines was not likely to be influenced by the knowledge of treatment assignment or the time-of-year administration, vaccinations of Group B patients were administered sooner than in the Group A 36 week treatment period.

At Day 1 and at Week 12, patients received an intradermal injection of 0.1 mL of C. albicans on the volar surface of the forearm. Forty-eight to 72 hours after each injection, patients were evaluated for a delayed-type hypersensitivity response by measuring the diameter of induration (palpable raised, hardened area of the forearm skin).

On Day 1, patients received a tetanus toxoid adsorbed booster vaccine (1 mg in 0.5 mL) IM injection in the deltoid muscle. Serum levels of tetanus toxoid titers were obtained immediately prior to and 4 weeks after administration of the tetanus toxoid adsorbed vaccine.

At Week 4, patients received an IM injection of the 23-valent pneumococcal polysaccharide vaccine (0.5 mL) in the deltoid muscle. Serum levels for antibodies to 12 pneumococcal serotypes were measured at Day 1, and immediately prior to and 4 weeks after administration of the pneumococcal vaccine.

At Weeks 8 and 9, patients received SC keyhole limpet hemocyanin 1 mg. Serum anti-keyhole limpet hemocyanin antibody levels were measured at Day 1, and immediately prior to and 4 weeks after the first administration of keyhole limpet hemocyanin.

Upon completion of the Week 12 visit, Group B patients with active rheumatic arthritis, defined as a swollen joint count (SJC) ≥ 4 (66 joint count) and a tender joint count (TJC) ≥ 6 (68 joint count) were eligible for treatment with 2 infusions of rituximab 1000 mg IV, 14 days apart. Patients received the first infusion of rituximab within 2 weeks after completing the Week 12 visit and after the second C. albicans skin test had been read. Patients received methylprednisolone 100 mg IV before each infusion of rituximab.

Group B patients who received treatment with rituximab completed the treatment period through Week 36 and, if qualified, had the option of entering the optional extension re-treatment period. Patients who did not qualify for or who did not choose to receive the optional extension re-treatment entered the approximately 1-year safety follow-up period. After the safety follow-up period, patients who remained peripherally CD19-positive B-cell depleted entered the B-cell follow-up period where they were followed every 12 weeks until their peripheral CD19-positive B cells returned to baseline values or the lower limit of normal, whichever was lower.

Group B patients who did not qualify for and/or did not choose treatment with rituximab completed the study at the end of the primary study period (Week 12).

Inclusion criteria

• Age 18-65 years.
• Diagnosis of rheumatoid arthritis (RA) for at least 6 months.
• Receiving treatment for RA on an outpatient basis.
• Use of methotrexate (MTX) at a dose of 10-25 mg/wk (oral [PO] or subcutaneous [SC]) for at least 12 weeks prior to Day 1, with the dose stable during the last 4 weeks prior to Day 1 (first day of the treatment period).
• If taking a background corticosteroid, use of the corticosteroid must be for at least 12 weeks prior to Day 1 at a stable dose during the last 4 weeks prior to Day 1.
• If taking one non-steroidal anti-inflammatory drug (NSAID), use of a stable dose for at least 2 weeks prior to Day 1.

Exclusion criteria

• Rheumatic autoimmune disease other than RA or significant systemic involvement secondary to RA; Sjogren's syndrome with RA is permitted.