FDA approves Sylvant for rare Castleman’s disease

FDA approved siltuximab (Sylvant, Janssen Biotech) to treat patients with multicentric Castleman’s disease (MCD), a rare disorder similar to lymphoma.

Siltuximab is an injection that blocks a protein that stimulates abnormal growth of immune cells. It is meant for patients with MCD who do not have HIV or human herpes virus 8 (HHV-8). MCD is a rare blood disorder with high morbidity. It causes an abnormal overgrowth of immune cells in lymph nodes and related tissues in the body. It usually affects adults who often have fever, night sweats, weight loss, and weakness or fatigue because their body’s immune system is weakened and cannot fight infections.

MCD is so rare that it is difficult to track the number of cases. A recent US analysis estimates the incidence of MCD is approximately 1,100 to 1,300 Americans.

FDA reviewed siltuximab under its priority review program. The drug was also granted orphan drug designation.

A clinical trial of 79 participants with MCD who were HIV and HHV-8 negative evaluated siltuximab’s safety and effectiveness. Participants were randomly assigned to receive a combination of siltuximab and best supportive care, or placebo and best supportive care. Results showed 34% of participants treated with siltuximab and best supportive care experienced tumor response, while no participant treated with placebo and best supportive care did.

Pruritis, weight gain, rash, and increased levels of uric acid in the blood and upper respiratory tract infection, were the most commonly reported side effects.

"[Siltuximab] fills a significant unmet need for a difficult-to-treat patient population that previously had very limited clinically proven options," said Megan Farina, director of product communication, Janssen Global Services, LLC.

"[Siltuximab] has a role in the cancer space as MCD is a proliferative disease that acts very much like lymphoma. MCD is complex, and up until this point, physicians have tried to reduce lymph node masses and put the disease in remission through a combination of treatments [eg, surgery, radiation therapy, corticosteroids, chemotherapy, and immunotherapy]," Farina said. "While such treatments may initially help, MCD often returns."