The most serious adverse reactions were:

  * Serious Infections – [see Warnings and Precautions ( 5.1)] 
  * Neutropenia, particularly when used in combination with TNF blocking agents



The most common adverse reaction with KINERET is injection-site reactions. These reactions were the most common reason for withdrawing from studies.

The data described herein reflect exposure to KINERET in 3025 patients, including 2124 exposed for at least 6 months and 884 exposed for at least one year. Studies 1 and 4 used the recommended dose of 100 mg per day. The patients studied were representative of the general population of patients with rheumatoid arthritis.

Injection-site Reactions

The most common and consistently reported treatment-related adverse event associated with KINERET is injection-site reaction (ISR). In Studies 1 and 4, 71% of patients developed an ISR, which was typically reported within the first 4 weeks of therapy. The majority of ISRs were reported as mild (72.6% mild, 24.1% moderate and 3.2% severe). The ISRs typically lasted for 14 to 28 days and were characterized by 1 or more of the following: erythema, ecchymosis, inflammation, and pain.

Infections

In Studies 1 and 4 combined, the incidence of infection was 39% in the KINERET-treated patients and 37% in placebo-treated patients during the first 6 months of blinded treatment. The incidence of serious infections in Studies 1 and 4 was 2% in KINERET-treated patients and 1% in patients receiving placebo over 6 months. The incidence of serious infection over 1 year was 3% in KINERET-treated patients and 2% in patients receiving placebo. These infections consisted primarily of bacterial events such as cellulitis, pneumonia, and bone and joint infections. Majority of patients (73%) continued on study drug after the infection resolved. No serious opportunistic infections were reported. Patients with asthma appeared to be at higher risk of developing serious infections when treated with KINERET (8 of 177 patients, 4.5%) compared to placebo (0 of 50 patients, 0%).

In open-label extension studies, the overall rate of serious infections was stable over time and comparable to that observed in controlled trials. In clinical studies and postmarketing experience, cases of opportunistic infections have been observed and included fungal, mycobacterial and bacterial pathogens. Infections have been noted in all organ systems and have been reported in patients receiving KINERET alone or in combination with immunosuppressive agents.

In patients who received both KINERET and etanercept for up to 24 weeks, the incidence of serious infections was 7%. The most common infections consisted of bacterial pneumonia (4 cases) and cellulitis (4 cases). One patient with pulmonary fibrosis and pneumonia died due to respiratory failure.

Malignancies

Among 5300 RA patients treated with KINERET in clinical trials for a mean of 15 months (approximately 6400 patient years of treatment), 8 lymphomas were observed for a rate of 0.12 cases/100 patient years. This is 3.6 fold higher than the rate of lymphomas expected in the general population, based on the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) database. 3An increased rate of lymphoma, up to several fold, has been reported in the RA population, and may be further increased in patients with more severe disease activity. Thirty-seven malignancies other than lymphoma were observed. Of these, the most common were breast, respiratory system, and digestive system. There were 3 melanomas observed in Study 4 and its long-term open-label extension, greater than the 1 expected case. The significance of this finding is not known. While patients with RA, particularly those with highly active disease, may be at a higher risk (up to several fold) for the development of lymphoma, the role of IL-1 blockers in the development of malignancy is not known. 

Hematologic Events

In placebo-controlled studies with KINERET, 8% of patients receiving KINERET had decreases in total white blood counts of at least one WHO toxicity grade, compared with 2% of placebo patients. Nine KINERET-treated patients (0.4%) developed neutropenia (ANC < 1 x 10 9/L). 9 % of patients receiving KINERET had increases in eosinophil differential percentage of at least one WHO toxicity grade, compared with 3 % of placebo patients. Of patients treated concurrently with KINERET and etanercept 2% developed neutropenia (ANC < 1 x 10 9/L). While neutropenic, one patient developed cellulitis which recovered with antibiotic therapy. 2% of patients receiving KINERET had decreases in platelets, all of WHO toxicity grade one, compared to 0% of placebo patients. 

Hypersensitivity Reactions

Hypersensitivity reactions including anaphylactic reactions, angioedema, urticaria, rash, and pruritus have been reported with KINERET.

Immunogenicity

As with all therapeutic proteins, there is potential for immunogenicity. In Studies 1 and 4, from which data is available for up to 36 months, 49% of patients tested positive for anti-anakinra binding antibodies at one or more time points using a biosensor assay. Of the 1615 patients with available data at Week 12 or later, 30 (2%) tested positive for neutralizing antibodies in a cell-based bioassay. Of the 13 patients with available follow-up data, 5 patients remained positive for neutralizing antibodies at the end of the studies. No correlation between antibody development and adverse events was observed.

The detection of antibody formation is highly dependent on the sensitivity and specificity of the assays. Additionally, the observed incidence of antibody (including neutralizing antibody) positivity in an assay may be influenced by several factors, including sample handling, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to KINERET with the incidence of antibodies to other products may be misleading.

Lipids

Cholesterol elevations were observed in some patients treated with KINERET.

Other Adverse Events

Table 1reflects adverse events in Studies 1 and 4, that occurred with a frequency of ≥ 5% in KINERET-treated patients over a 6-month period.