The US Food and Drug Administration has cleared Johnson & Johnson’s Darzalex as a treatment for patients with multiple myeloma.

The agency said the drug, which is now the first monoclonal antibody approved to treat the blood cancer, can be used in patients who have received at least three prior therapies.

Dazalex (daratumumab), which carries orphan drug status in both the EU and US, works by binding to a signalling molecule found on the surface of multiple myeloma cells called CD38 to trigger the patient’s own immune system to attack the cancer cells.

Approval follows safety and efficacy data from two open-label studies: in one, of 106 participants receiving Darzalex, 29% experienced a complete or partial reduction in their tumour burden, which lasted for an average of 7.4 months; and in the second, of 42 receiving the drug, 36% had a complete or partial response.

The most common side effects were infusion-related reactions, fatigue, nausea, back pain, fever and cough, but the Darzalex may also result in low counts of infection-fighting white blood cells or red blood cells and low levels of blood platelets, the FDA noted.

J&J group Janssen filed the drug in Europe in September.