Regulators in the USA have moved quickly to give the green light to Amgen’s cancer immunotherapy blinatumomab for the treatment of a rare type of leukaemia.

The US Food and Drug Administration has approved blinatumomab, which will be marketed as Blincyto, to treat patients with Philadelphia chromosome-negative precursor B-cell acute lymphoblastic leukaemia (B-cell ALL). The thumbs-up makes the immunotherapy the first approved drug that engages the body’s T-cells to destroy leukaemia cells.

The drug acts as a connector between a protein called CD19, which is found on the surface of most B-cell lymphoblasts, and CD3, a protein on T-cell lymphocytes. It is intended for patients whose cancer returned after treatment or did not respond to previous therapy.

The FDA had granted Blincyto breakthrough therapy designation and a priority review and it has been approved more than five months ahead of its action date of May 19, 2015. Richard Pazdur, director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, said “immunotherapies, especially Blincyto with its unique mechanism of action, are particularly promising for patients with leukaemia”.

32% achieved complete remission for 6.7 months

He noted that the agency recognised “the potential of this novel therapy [and] worked proactively with the sponsor…to facilitate the approval of this novel agent”. The approval is based on a study where participants were treated with Blincyto for at least four weeks via infusion; 32% had no evidence of disease for approximately 6.7 months.

Blincyto carries a boxed warning that some trial participants had problems with low blood pressure and difficulty breathing at the start of the first treatment, experienced a short period of difficulty with thinking or other side effects in the nervous system. The approval comes with a risk evaluation and mitigation strategy.

Amgen R&D chief Sean Harper said the accelerated approval “underscores the critical need for new treatment options for patients with relapsed or refractory B-cell precursor ALL, who are often young adults”. He added that Blincyto represents the first clinical and regulatory validation of the firm’s BiTE (Bispecific T cell engager) platform, “a new and innovative approach that helps the body's own immune system fight cancer”.