ABP798 is an experimental immuno-oncology anti-CD20 monoclonal antibody for the treatment of non-Hodgkin’s lymphoma (NHL), chronic lymphocytic leukemia (CLL), rheumatoid arthritis (RA), granulomatosis with polyangiitis, and microscopic polyangiitis.

The drug is being developed by Amgen in collaboration with Allergan as a Rituxan (rituximab) biosimilar after Rituxan’s patent has expired in the U.S. in September 2016, and in Europe in February 2013.

biosimilar is a biological product that has been demonstrated to be highly similar to another existing biological product approved by the U.S. Food and Drug Administration (FDA). It should have no clinically meaningful differences in terms of safety and effectiveness from the reference product. Biosimilars are usually manufactured by a concurrent company after the patent for the original product has expired.

How ABP798 works

Like Rituxan, ABP798 is a monoclonal antibody (a protein designed to target and attach to a specific protein) that is expected to work by targeting the CD20 antigen, a protein found on the surface of B-cells and frequently overexpressed in various cancers. By binding to CD20, the drug triggers the death of the B-cells, which reduces the number of cancerous ones present in the body. In this way, ABP798 interferes with the growth and spread of leukemia and lymphoma cancer cells.

In RA, an autoimmune disease characterized by chronic inflammation of the joints, CD20 also plays an important role by helping B-cells in the maintenance of the inflammatory state. So, inhibiting CD20 depletes mature B-cells and limits their ability to promote inflammation.

ABP798 in clinical trials

ABP798’s binding capacity to CD20, its antibody-dependent cell-mediated cytotoxicity (ADCC), and complement-dependent cytotoxicity (CDC) responses toward CD20-expressing cells, as well as its capacity to induce programmed cell death, were assessed in a study to confirm its potential as a biosimilar to Rituxan. The results of the study, presented at 22nd Congress of the European Hematology Association (EHA) in 2017 showed that ABP798 was comparable to Rituxan in all the tests performed, suggesting it is similar to Rituxan in terms of biological activity. These findings provided the foundation for ABP798’s further clinical development.

The safety and effectiveness of ABP798 in patients with CD 20 positive B-cell NHL are being evaluated in a Phase 3 clinical trial (NCT02747043). The study also is evaluating whether the effect of the biosimilar is comparable to what is seen for the licensed medicine, Rituxan. The trial is still recruiting patients.

The same evaluation is being performed in a Phase 3 study (NCT02792699) in patients with moderate-to-severe RA.


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