Do you need to be in a complete remission to proceed with an autologous stem cell transplant (ASCT)? Should you postpone transplant to get into a deeper remission?

Do you need to be in a complete response (CR) to proceed with autologous stem cell transplant (ASCT)?

As a reminder, a complete response, sometimes called a complete remission, is a treatment outcome where no detectable evidence of myeloma can be found in the body, meaning there is no measurable M-protein in the blood or urine, and less than 5% plasma cells are present in the bone marrow biopsy.

So the depth information that someone sees as their goal when they're undergoing their initial treatment is always considered in a little bit of a strange light. Better is always a deeper remission, but some individuals' disease does not seem to allow them to get into the deepest remission possible. And some patients have a fair amount of toxicity with some particular therapies, and decisions had to be made about how hard to push an individual person to get the depth of disease response.

Complete remission is a wonderful goal and we know that a deeper remission is better overall. But I don't think it's fair to say that you have to be in a complete remission when you go to a transplant. It's a conversation with the transplant physician about each individual's disease history, their disease course, and their tolerance to the different treatments in the context of the rest of that patient's medical life and their medical conditions.

And there are some cases where even if a person has only achieved a deep, deep partial remission, that the decision may be made to go on to transplant because it's thought to be the next best tool that we have available. Stem cell transplant is associated with deeper responses, higher rate of complete remission and higher rate of MRD negative disease, higher rate of progression-free survival, and better overall survival.

All these studies were done with whatever the available induction treatments were, and most of the patients get a finite number of between 4 to 6 cycles. Now we have more effective treatments where patients actually achieve a complete remission, a significant proportion. There were times where fewer than 10% would actually achieve a complete remission and we would still harvest their stem cells and do that transplant.

So the data support that even with the presence of residual disease in the bone marrow, you can safely do this procedure and achieve a deep remission. Of course, we would like to see as deep remission as possible, but people have looked at that in analysis from registry data from different centers that is there any benefit to continuing treatment for a longer period of time until the patient achieves the complete remission?

So there was actually a paper published from the Center for International Bone Marrow Transplant Registry in 2015. Dr. Veech from Washington University was the first doctor to look at that data, and they basically showed that even patients who were not able to achieve even a partial remission, they divided them into two groups. There were some half of them got additional treatment to deepen their response, and the other half who went on to get transplant, whatever their response level was.

And many of us actually at that time gave chemotherapy before we harvested the stem cells, the chemo mobilization. And what they showed was that those who got additional treatment and got a deeper response did as well as the ones who did not.

So at this point, the data support that you give a finite number of cycles, 4 to 6 cycles, and most of the patients in this DNA achieve a partial remission. And then we can go on to harvest their stem cells and proceed to transplant. If we continue to give treatment, there are no data that we are actually going to help those patients, and in some ways, we may hurt because more treatment means difficulty collecting an adequate number of stem cells.

Sometimes that may adversely affect the quality of stem cells. And as we all know, these treatments are not without side effects. So by continuing to treat patients, we may actually cause more side effects and perhaps increase the morbidities.

So it's perfectly safe to do a finite number of treatments, and as long as a patient is responding, harvest the stem cells and proceed with the transplant.