What is leukapheresis?

What is Leukophoresis? So the first step in CAR T cell therapy is something called Leukophoresis or aphoresis for short. It's a process where we connect the patient to a machine that looks very similar to dialysis machine. It circulates the patient's blood for several hours and collects lymphocytes, puts them in a bag so we can use them for this process of genetic modification. It's a fairly harmless procedure. A lot of patients with myeloma are familiar with a similar procedure that is used to collect stem cells if they're undergoing an autologous stem cell transplant for their disease. Some lymphoma patients undergo a similar procedure as well. This one is in fact simpler because we're not collecting stem cells. We're just collecting healthy lymphocytes from the blood. So it does not require injections of growth factors for several days. It has minimal side effects and it always ends in a single day as opposed to stem cell collections that in many patients would require multiple days and multiple sessions on the aphoresis machine. So the process of Leukophoresis to get the CAR T cell produced is similar to the dialysis process. The patient will go to an aphoresis unit, sit there for a few hours and then harvest those T cells that will be sent to a lab for manufacturing. Usually this process will take a few hours and it's variable from patient to patient. So in general we can think about this process as a process where a patient go to an aphoresis lab usually similar to the dialysis machine, hook up to that for a few hours, collect those T cells and send them to a special place where they manufacture them and make them ready for infusion. Harvesting the T cells that are used for CAR T product manufacture is actually different than harvesting the stem cells. The reason why, because those T cells are available in the blood and we don't need to induce them and make them in a higher amount before we do it. So we usually don't use medications that we use for stem cell transplant like growth factors. So the amount of CAR T cells or actually the T cells that are initially collected is variable and it depends on patient and also depends on the product. Many products have a threshold that they need to reach to before they call the manufacturing as a success. This usually comes in millions of cells and it's variable according to the product. Once the company reaches this target level they will contact the physician who ordered the CAR T cells and arrange for a time that those cells will shift to the center where they will be infused. The process itself is taking time and usually it takes anything between 4 to 5 weeks to produce those cells. There is concern of doing this process late in the process of myeloma treatment because patients who are exposed to different treatment options they may have lower T cell in their body. So it may be difficult for the company to produce those cells in a sufficient amount. And what we are dealing with in real life is that some patients may fail to produce the target level of those CAR T cells and at that time now we need to apply to get a specific approval to use the lower dose of them in a specific patient. But I think this will be a problem because many patients may be exposed to other medications before they get the CAR T product. But there are ways around that and hopefully with us improving on the process we do we will be able to overcome this problem.