Siltuximab

SYLVANT is indicated for the treatment of patients with multicentric Castleman's disease (MCD) who are human immunodeficiency virus (HIV) negative and human herpesvirus-8 (HHV-8) negative. SYLVANT is an interleukin-6 (IL-6) antagonist indicated for the treatment of patients with multicentric Castleman's disease (MCD) who are human immunodeficiency virus (HIV) negative and human herpesvirus-8 (HHV-8) negative. Limitations of Use SYLVANT was not studied in patients with MCD who are HIV positive or HHV-8 positive because SYLVANT did not bind to virally produced IL-6 in a nonclinical study.

Siltuximab binds human IL-6 and prevents the binding of IL-6 to both soluble and membrane-bound IL-6 receptors. IL-6 has been shown to be involved in diverse normal physiologic processes such as induction of immunoglobulin secretion. Overproduction of IL-6 has been linked to systemic manifestations in patients with MCD.

For intravenous infusion only. Administer as an 11 mg/kg dose given over 1 hour by intravenous infusion every 3 weeks. Recommended Dosage Administer SYLVANT 11 mg/kg over 1 hour as an intravenous infusion every 3 weeks until treatment failure. Perform hematology laboratory tests prior to each dose of SYLVANT therapy for the first 12 months and every 3 dosing cycles thereafter. If treatment criteria outlined in Table 1 are not met, consider delaying treatment with SYLVANT. Do not reduce dose. Table 1: Treatment Criteria Laboratory parameter Requirements before first SYLVANT administration Retreatment criteria Absolute Neutrophil Count ≥1.0 × 10 9 /L ≥1.0 × 10 9 /L Platelet count ≥75 × 10 9 /L ≥50 × 10 9 /L Hemoglobin SYLVANT may increase hemoglobin levels in MCD patients <17 g/dL <17 g/dL Do not administer SYLVANT to patients with severe infections until the infection resolves.

Severe hypersensitivity reaction to siltuximab or any of the excipients in SYLVANT. Hypersensitivity reactions, including anaphylactic reaction, hypersensitivity, and drug hypersensitivity have been reported in patients treated with siltuximab.

Concurrent Active Severe Infections: Do not administer SYLVANT to patients with severe infections, monitor for infections, institute prompt treatment, and interrupt SYLVANT until resolution of infection. Vaccinations: Do not administer live vaccines because IL-6 inhibition may interfere with the normal immune response to new antigens. Infusion Related Reactions: Administer SYLVANT in a setting that provides resuscitation equipment, medication, and personnel trained to provide resuscitation. Gastrointestinal (GI) perforation: Promptly evaluate patients presenting with symptoms that may be associated or suggestive of GI perforation.

The following clinically significant adverse reactions are also discussed in other sections of the labeling: Concurrent active severe infections Infusion-related reactions and hypersensitivity Gastrointestinal perforation The most common adverse reactions (>10% of patients) were rash, pruritus, upper respiratory tract infection, increased weight, and hyperuricemia.

Cytochrome P450 Substrates Cytochrome P450s in the liver are down regulated by infection and inflammation stimuli including cytokines such as IL-6. Inhibition of IL-6 signaling in patients treated with SYLVANT may restore CYP450 activities to higher levels leading to increased metabolism of drugs that are CYP450 substrates compared to metabolism prior to treatment with SYLVANT. Upon initiation or discontinuation of SYLVANT, in patients being treated with CYP450 substrates with a narrow therapeutic index, perform therapeutic monitoring of effect (e.g., warfarin) or drug concentration (e.g., cyclosporine or theophylline) as needed and adjust dose. The effect of SYLVANT on CYP450 enzyme activity can persist for several weeks after stopping therapy.

and Stability SYLVANT must be refrigerated at 2°C to 8°C (36°F to 46°F) in the original carton to protect from light. Do not freeze.