US regulators have issued a green light for Janssen's Sylvant (siltuximab) to treat patients with the rare blood disorder multicentric Castleman’s disease (MCD), making it the first to be approved for the condition.

MCD induces an abnormal overgrowth of immune cells in lymph nodes and related tissues in the body, acting very similar to lymphoma; patients' immune systems are weakened and cannot fight infection, and the disease has a high morbidity rate.

Sylvant is an anti-interleukin-6 chimeric monoclonal antibody given via an injection to block a protein that stimulates this abnormal growth.

The US Food and Drug Administration (FDA) noted that data from clinical trials showed that 34% of MCD patients given Sylvant and best supportive care experienced a tumour response, while none in the placebo arm did.

"There has been a serious need for treatment options for patients with MCD," said Frits van Rhee, University of Arkansas for Medical Sciences, and MCD2001 study lead investigator. 

"MCD is a complex disease and up until this point, physicians have tried to reduce lymph node masses and put the disease in remission through a combination of treatments, but MCD often returns," he noted, stressing that the approval of Sylvant "gives physicians a long-awaited treatment option for a group of patients who has been suffering with this chronic, serious and debilitating disease".

The drug was assessed under the FDA's priority review program, and things are also looking good in Europe, where advisors to the European Medicines Agency recommended Sylvant's approval in March.