What is plasma cell leukemia? What is the difference between primary PCL and secondary PCL?
Plasma cell leukemia is when you have circulating plasma cells in your blood, essentially that's what the meaning of the term is. It's a rare presentation of multiple myeloma, about 1 to 4% of newly diagnosed patients will present with plasma cell leukemia.
And the cutoff for us to call someone is having plasma cell leukemia is if they have more than 5% plasma cells in their blood, in the peripheral blood. So it's not the bone marrow, it's not the flow cytometry. That's it on the bone marrow, but just a regular blood test.
There are two different types of plasma cell leukemias. One is what we call is the primary plasma cell leukemia, which is when you were diagnosed with multiple myeloma, you had circulating more than 5% circulating plasma cells to begin with. So that would be a primary plasma cell leukemia.
On the other hand, there are patients who start off as myeloma without circulating plasma cells, but over the course of their disease, they start having these plasma cells show up in their blood. So if this develops later on in the course of the disease and we call it a secondary plasma cell leukemia. In general, the prognosis is not good for both of these presentations.
It usually means that you have an aggressive variety of multiple myeloma, but primary plasma cells leukemia. Typically, we tend to use some of our most strongest treatments upfront and try to get patients up for a transplant as soon as possible, because that has shown to have patients have been shown to have better outcomes if they get a transplant sooner with the primary plasma cell leukemia.
Secondary plasma cell leukemia, like I said, usually develops later on in the course of the disease. It usually indicates that the disease has become more aggressive. It has maybe become more refractory to the treatment you have had.
Unfortunately, we most of the trials and with CAR-T and some of the newer treatments often tend to exclude patients with plasma cell leukemia. In those situations, if conventional therapies and commonly available treatments have not been successful, then you have to try the novel therapies like CAR-T and Bispecifics in those situations.
That just means you have circulating plasma cells in the peripheral blood. Plasma cell leukemia, I think you can consider that as an extension of multiple myeloma, but it's usually considered very aggressive. And you need to rapidly reduce disease burden.
So oftentimes depends on the patient, depends on the case, in primary plasma cell leukemia, we end up utilizing aggressive side or reduction with chemotherapy agents like you probably have heard of pace like VD-PACE and KD-PACE.
Essentially a combination of four or five intense chemotherapies that rapidly reduce the disease burden. And then you can go on to doing a quadruplet or induction regimen to get them into remission, then stem cell transplant. So you have to be very aggressive in managing plasma, whether it's primary or secondary plasma cell leukemia.
And we still have a long way to go. A lot of clinical trials exclude patients who have plasma cell leukemia. And I feel that has to change in the coming future.
Primary PCL is where the patients present with circulating plasma cells. It's not clear how that arose because we don't know previously, because they're presenting with a new diagnosis. But again, it's a very aggressive disease and it needs to be treated aggressively.
We do have treatment modalities that allow this to be controlled and controlled for a long period of time. It used to be a real problem, and now it's gotten better with better therapies, especially with the new agents.
Secondly, plasma cell leukemia is the less good prognosis because usually these patients have received prior therapy and if they receive a lot of prior agents and are running out of treatment options, it often is a signal for a far more aggressive disease that could be very life threatening.
HealthTree • July 14, 2025
