The European Commission granted a marketing authorization valid throughout the European Union for blinatumomab on 23 November 2015. Blinatumomab is a cancer medicine used to treat adult patients with B-precursor acute lymphoblastic leukaemia (ALL), a type of blood cancer. In B-precursor ALL, certain cells that give rise to B-cells multiply too quickly and eventually these abnormal cells replace normal blood cells. Blinatumomab is used when the ALL has come back or has not responded to previous treatment. It is used when the patients are āPhiladelphia-chromosome-negativeā (Ph-). This means that some of their genes are not reāarranged forming a special chromosome called the Philadelphia chromosome, which is found in some patients with ALL. Blinatumomab was designated an āorphan medicineā on 24 July 2009. Blinatumomab is a type of antibody that has been designed to recognise and attach to two proteins:
- CD19, which is found on the surface of all B-cells, including ALL cells;
- CD3 on the surface of T-cells (cells of the immune system responsible for killing pathogens and cancer cells).
Blinatumomab acts as a ābridgeā to bring the T-cells and the B-cells together. This activates T-cells, which release substances that eventually kill B-cells.
Blinatumomab has been studied in one main study in 189 patients with Ph- B-cell precursor ALL whose leukaemia had come back or had not responded to treatment. Patients were given Blinatumomab for up to five treatment cycles. In this study, Blinatumomab was not compared with any other treatment. The main measure of effectiveness was based on the percentage of patients who, after two treatment cycles, responded to treatment, measured as resolution of signs of leukaemia and complete or partial normalisation of blood cell counts. The study showed that 42.9% (81 out of 189) of patients given Blinatumomab responded to treatment. In most patients who had a response, there was no evidence of cancer cells left. The average survival time before the cancer came back was around 6 months, which could enable suitable patients to undergo a blood stem cell transplant. The most common side effects with Blinatumomab are infusion-related reactions, infections, pyrexia, headache, febrile neutropenia, peripheral edema, nausea, hypokalaemia, constipation, anaemia, cough, diarrhoea, tremor, neutropenia, abdominal pain, insomnia, fatigue and chills. The most serious side effects were infections, neurologic events, neutropenia with or without fever, cytokine release syndrome, and tumour lysis syndrome. Since Blinatumomab has been granted a conditional approval, the company that markets Blinatumomab will provide data from a larger study comparing the effectiveness Blinatumomab to standard chemotherapy in Ph- B-precursor ALL patients. An additional study will look at the safety and use of Blinatumomab in clinical practise.