There are 4 monoclonal antibodies approved to treat CLL, but in reality, only 2 of them, rituximab and Obinutuzumab (Gazyva) are commonly used these days.
Alemtuzumab was the very first monoclonal antibody (mAb) and was developed at CAMbridge, hence the name, CAMPATH. Unlike the other 3 approved mAbs for CLL that target CD20 found on normal and cancerous B cells, alemtuzumab targets CD52, a surface marker found on both normal and abnormal B and T cells. It can be extremely effective in CLL, especially in cleaning out residual disease in the marrow, but because it wipes out both B and T cells, there are high rates of life-threatening opportunistic infections associated with its use. It essentially wipes out much of the adaptive immune system and should only be used in conjunction with broad antimicrobial prophylaxis.
As such, it is rarely given these days to treat CLL. We have safer more effective therapies. In fact, it is used so rarely, that the manufacturer gives it away for free to treat CLL. Before you get too excited about the largess of the pharmaceutical industry, this was done so they could charge more for the same drug to treat multiple sclerosis (MS) where it helps by turning off the immune destruction seen in that disorder. This article from 2012 provide the interesting back story.
Now ofatumumab or Arzerra joins the free club. Ofatumumab is great anti CD20 mAb and was the upcoming new thing in CLL around 2012 and a like saver for some. However, most CLL experts would argue that the newest kid on the block, obinutuzumab is an even better antibody. Rituximab has a longer track record, is better known and is now available as a less expensive biosimilar so ofatumumab is rarely used. Ublituximab is another promising anti-CD20 mAb late in development, so the market for Arzerra in treating CLL would likely continue to shrink and there is money to be saved in not marketing a drug with little sales.
I don’t begin to understand all the logic behind these business decisions, but I am very grateful to Novartis (Genmab) for this move that has the potential to benefit many CLL patients.
Wait a minute! Ofatumumab was just approved to treat MS Aug 20/2020 at a much lower dose (20 mg self-administered subcutaneously for MS versus 1,000 mg IV for CLL). This is same day as the announcement that it will be free for CLL. Sound familiar to the Campath story?
Here is a link to the press release about the change to free drug, so whatever the cause, I remain grateful.
For more on the basics of mAbs and all the other immune therapies, I wrote this.
For a background on the complicated names of monoclonal antibodies, please see my recent explanation here.
Stay strong. We are all in this together