Blinatumomab

 Blinatumomab (trade name Blincyto, previously known as AMG103) is a biopharmaceutical drug used as a second-line treatmentfor Philadelphia chromosome-negative relapsed or refractory acute lymphoblastic leukemia. It belongs to a class of constructedmonoclonal antibodies, bi-specific T-cell engagers (BiTEs), that exert action selectively and direct the human immune system to act against tumor cells. Blinatumomab specifically targets the CD19 antigen present on B cells.^[1] In December 2014 it was approved by the US Food and Drug Administration under the accelerated approval program; marketing authorization depended on the outcome of clinical trials that were ongoing at the time of approval.^[2][3] When it launched, blinatumomab was priced at $178,000 per year in the United States; only about 1,000 people were eligible to take the drug, based on its label.^[4]

Medical use

Blinatumomab is used as a second-line treatment for Philadelphia chromosome-negative relapsed or refractory Bcell precursor acute lymphoblastic leukemia.^[2]

Mechanism of action

Blinatumomab enables a patient’s T cells to recognize malignant B cells. A molecule of blinatumomab combines two binding sites: aCD3 site for T cells and a CD19 site for the target B cells. CD3 is part of the T cell receptor. The drug works by linking these two cell types and activating the T cell to exert cytotoxic activity on the target cell.^[5] CD3 and CD19 are expressed in both pediatric and adult patients, making blinatumomab a potential therapeutic option for both pediatric and adult populations.^[6]

History

The drug was developed by a German-American company Micromet, Inc. in cooperation with Lonza; Micromet was later purchased byAmgen, which has furthered the drug’s clinical trials. In July 2014, the FDA granted breakthrough therapy status to blinatumomab for the treatment of acute lymphoblastic leukemia (ALL).^[7] In October 2014, Amgen’s Biologics License Application for blinatumomab was granted priority review designation by the FDA, thus establishing a deadline of May 19, 2015 for completion of the FDA review process.^[8]

On December 3, 2014, the drug was approved for use in the United States to treat Philadelphia chromosome-negative relapsed or refractory acute lymphoblastic leukemia under the FDA‘s accelerated approval program; marketing authorization depended on the outcome of clinical trials that were ongoing at the time of approval.^[2][9]

Cost

When blinatumomab was approved, Amgen announced that the price for the drug would be $178,000 per year, which made it the most expensive cancer drug on the market. Merck’s pembrolizumab was priced at $150,000 per year when it launched; unlike that drug and others, only about 1,000 people can be given the drug, based on its label.^[4]

Peter Bach, director of the Center for Health Policy and Outcomes at Memorial Sloan-Kettering Cancer Center, has calculated that according to “value-based pricing,” assuming that the value of a year of life is $120,000 with a 15% “toxicity discount,” the market price of blinaumomab should be $12,612 a month, compared to the market price of $64,260 a month. A representative of Amgen said, “The price of Blincyto reflects the significant clinical, economic and humanistic value of the product to patients and the health-care system. The price also reflects the complexity of developing, manufacturing and reliably supplying innovative biologic medicines.”^[10]