Rituxan

How does it remove the cells?

By making them conspicuous. Once the antibody is stuck to CD20, the tail it leaves projecting outward is recognized by natural killer cells and scavenging cells, which destroy the flagged cell, and it also triggers the complement proteins that punch holes in membranes. Some direct signaling toward cell death occurs as well. What makes the target a good one is where CD20 is absent. Blood forming stem cells do not carry it, so the marrow can rebuild the B cell population afterward, and mature plasma cells, the factories already producing antibody, have largely shed it, so existing protective antibody levels are not wiped out. B cells stay depleted for months after a course before returning. One point is often stated incorrectly: rituximab is a chimeric antibody, with a mouse derived binding region grafted onto a human framework, rather than a fully humanized one, and that mouse portion contributes to the reactions seen during infusion.

What is it used for?

What comes with treatment?

It is given as an intravenous infusion lasting hours, most often slowly on the first occasion because reactions with fever, chills, rash and low blood pressure are common as the first wave of cells breaks down. A form injected under the skin is available for some uses once the first dose has been tolerated. Because B cells help hold dormant hepatitis B in check, the virus can reactivate in someone who has had it in the past, so testing beforehand is routine. Repeated courses lower antibody levels and raise the risk of infection, and a rare brain infection has been reported. Rituximab is now also supplied as biosimilar versions, which are separate products developed to match the original closely rather than generic copies of it.