FDA Approves Sylvant (Siltuximab) for Castleman Disease

The US Food and Drug Administration (FDA) has approved the drug Sylvant (siltuximab) to treat multicentric Castleman disease, the most serious type of Castleman disease. Castleman disease causes abnormal cell growth in lymph nodes and related tissues. It is not a type of cancer, but the multicentric form of the disease acts a lot like cancer of the lymph nodes (lymphoma), and many people with Castleman disease eventually develop lymphoma.

Lymph nodes and other lymphoid tissues are part of the body’s immune system. Sylvant works by blocking a protein that helps immune cells to grow abnormally. However, the drug hasn’t been shown to help Castleman disease patients who are infected with either HIV or human herpes virus 8 (HHV-8).

Sylvant was reviewed under the FDA’s priority review program that can speed up the approval process for drugs that have the potential to significantly improve treatment of a serious condition.

The FDA based its approval on a clinical trial of 79 people with multicentric Castleman disease who did not have HIV or HHV-8. They received their regular care plus Sylvant, or their regular care and a placebo (fake drug). Results showed that 34% of those who received regular care plus Sylvant had their tumors shrink, compared to none of those who received regular care and a placebo.

The drug is given through a vein, usually every 3 weeks. Side effects tend to be mild and include rash, itching, swelling, weight gain, and respiratory infections such as colds. Some patients also have side effects during the infusion, such as flushing (skin redness with a feeling of warmth), chest pain, back pain, nausea, and rapid heartbeat.

Sylvant is marketed by Janssen Biotech Inc.

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