This is the ninth part of our series about the condition based on our patient booklet “Fast Facts for Patients: Waldenström Macroglobulinemia”. This is the second of two blog posts on further types of treatment for Waldenström macroglobulinemia (WM).
B-cell lymphoma-2 (BCL-2) is a protein that is often overproduced in blood cancers. It can help cancer cells overcome the normal controls on growth and division. Venetoclax is an example of a BCL-2 inhibitor. It is not readily available outside of clinical trials.
Nivolumab and pembrolizumab are medications that block the effects of a protein called PD-1. They help restore the body’s natural capacity to fight cancer cells. These medications are called immune checkpoint inhibitors. They are not available for the treatment of WM outside of clinical trials.
When WM comes back some people may have treatment using their own stem cells. This is called autologous stem cell transplant (ASCT). Stem cells from a donor can also be transplanted. This is called allogeneic stem cell transplant (allo-SCT).
Stem cell transplants involve a specific type of stem cell called hematopoietic (blood-producing) cells, which are found in the bone marrow. All the different types of blood cell develop from these cells.
The stem cells can be collected from a donor or the person themselves – the processes are described in the next sections.
There are potentially serious side effects associated with these treatments. They are not suitable for everyone and are not done routinely. Doctors consider a person’s general health and fitness before recommending them. For some people with other health problems, particularly older people, the risks of carrying out a stem cell transplant are too high to recommend this approach.
Stem cell transplants are only performed after chemotherapy. The chemotherapy puts the disease into a remission so that healthy cells can grow.
If stem cell transplant is an option, it would normally be carried out after a maximum of two previous treatments, as this is when it gives the best results.
High-Dose Chemotherapy and ASCT
A person having an ASCT will have some of their own stem cells collected and stored so they can be put back into their body as rescue cells after chemotherapy.
Before the cells are collected, therapy is given to reduce the number of abnormal cells in the bone marrow. This chemotherapy is typically given orally (tablets) and/or by injection and/or intravenously (into a vein) in cycles over several months.
Once the cells have been collected, high-dose chemotherapy is given to kill any remaining abnormal cells.
Then the person’s stem cells are returned to the body by a drip into a vein, like a blood transfusion. The cells make their way to the bone marrow, where they form new blood cells. This takes 7–10 days. During this period, the person is particularly vulnerable to infection. Because of this, they need inpatient treatment and monitoring.
This treatment does not cure WM, but it can lead to a long-lasting remission. In other words, the disease can stay at a very low level for quite a long time (typically a number of years) before further treatment is needed.
In this kind of transplant, the stem cells come from another person and are used as an immune therapy against the WM.
Once a donor match is secured, high-dose chemotherapy is given and the donor’s previously collected stem cells are infused into the bloodstream via a cannula. Within 2–3 weeks, donor blood cells appear in the person’s bone marrow.
There is an ongoing risk that the donor immune system may react against the person’s healthy tissues as well as the WM cells. This is called graft-versus-host disease, and it can cause a variety of complications after the transplant.
While this form of transplant can offer the possibility of cure for some people with WM, it is more hazardous than ASCT. The risks and benefits need to be weighed very carefully.
Information based on Fast Facts for Patients: Waldenström Macroglobulinemia (Karger, 2022).