Amgen’s cancer immunotherapy Blincyto has won conditional approval in Europe for the treatment of a rare type of leukaemia.

The European Commission says the drug can be used to treat adult patients with Philadelphia chromosome-negative (Ph-) relapsed or refractory B-precursor acute lymphoblastic leukaemia (ALL), a rapidly progressing cancer of the blood and bone marrow thought to affect around 900 patients a year in the region.

The outlook for patients with relapsed or refractory ALL is particularly bleak, with a median overall survival of just three to five months, highlighting the extreme level of unmet need.

Blincyto’s (blinatumomab) conditional authorisation comes on the back of data from Phase II trials, in one of which 42.9 percent of patients achieved complete remission (CR) or CR with partial haematological recovery when treated with the drug, marking “the first major advance in more than two decades for patients with this hard-to-treat cancer,” according to Max Topp, a professor at the Hospital of Wuerzburg in Germany.

Blincyto is an example of a BiTE antibody construct, a type of immunotherapy designed to help the body’s immune system to detect and target malignant cells. The modified antibodies engage two different targets simultaneously, thereby juxtaposing killer T cells to cancer cells to trigger apoptosis.

Under the conditional marketing approvals process in Europe, the drug’s license will need to be renewed every year and can only converted to full clearance once post-licensing commitments have been fulfilled. Accelerated approval was also issued by regulators in the US back in December 2014.