Tocilizumab may be effective and may lead to a sustained clinically meaningful improvement in children suffering from polyarticular Juvenile Idiopathic Arthritis.
Tocilizumab is a humanized recombinant antibody, which blocks the receptors where interleukin-6 (IL-6) attaches to the surface of cells. When IL-6 is unable to attach to these cells, they are prevented from driving inflammation. Elevated serum and joint fluid IL-6 levels have been shown to be associated with disease activity in patients with pcJIA.1
"JIA is a chronic arthritis occurring in 1 in every 1,000 children. With no known cause, it can lead to joint damage and permanent disability. These data show that tocilizumab rapidly improves signs and symptoms of pcJIA, with meaningful clinical responses maintained in a large proportion of patients at week 40," said lead author Dr. Fabrizio De Benedetti of the IRCCS Ospedale Pediatrico Bambino Gesu, Rome.
Speaking on behalf of the Paediatric Rheumatology International Trials Organisation (PRINTO) and Pediatric Rheumatology Collaborative Study Group (PRCSG), who had overseen this study, Dr. De Benedetti concluded that "these data suggest that tocilizumab is going to be a novel biologic part of the therapeutic armamentarium for pcJIA."
CHERISH is a two-year, 3-part trial being conducted at 58 centres across 15 countries. Patients aged 2-17 years were included in the study if they had active pcJIA for at least 6 months and had failed to respond to methotrexate (a cornerstone of therapy worldwide for this condition).
Part 1 of the study was a 16-week open-label phase in which 188 patients received tocilizumab every four weeks. The 166 patients who achieved at least a 30% improvement in symptoms and signs of pcJIA (an JIA ACR30* response) went on to part 2, which was a 24-week study in which patients were randomised to continue on the same dose of tocilizumab or to receive placebo. Part 3 is an ongoing open-label study.
For the primary end point of ACR30 flare, fewer patients in the tocilizumab group than in the placebo group experienced a flare by week 40 (25.6% vs. 48.1%) and JIA ACR30/50/70* responses were significantly higher with tocilizumab than placebo, with as many as 65% of the children attaining an ACR70 response.
Dosing of tocilizumab was based on the patient's body weight (BW): with a BW ¡Ý30 kg, the dose was 8 mg/kg [n=119]; with a BW <30 kg, patients were randomly assigned to 8 mg/kg [n=34] or 10 mg/kg [n=35].
"The degree of improvement at week 16 was lower for each of the endpoints for patients under 30 kg on 8 mg/kg tocilizumab than in the other two treatment groups. The data therefore support the efficacy of tocilizumab in pcJIA using a monthly regimen at doses of 8 mg/kg if BW 30 kg or more, and 10 mg/kg if BW under 30 kg," Dr. De Benedetti added.
Patients were also taking background medications, such as methotrexate and oral corticosteroids (79% and 46% respectively).
Tocilizumab's safety profile was consistent with that found in other tocilizumab-treated patients.2 At the safety data cut, 184 patient years of follow-up had occurred in the 188 patients enrolled. Infection was the most common adverse event (164/100 patient years) and serious adverse event (4.9/100 patient years). Liver enzyme (ALT/AST) elevations ¡Ý3¡Á upper limit of normal occurred in 3.7 % / <1% of patients, neutropenia (<1000 cells/mm3) in 3.7% of patients, thrombocytopenia (<50,000 cells/mm3) in 1.1% of patients. An elevation of LDL-cholesterol ¡Ý110 mg/dl was reported in 11.4% of patients who received tocilizumab.