FACULTY COMMENTS
DR JAKUBOWIAK: The Mazumder study demonstrates what was separately reported by the Mayo Clinic — namely, the IMiDs® seem to reduce the number of stem cells prior to transplant, thus increasing the number of phereses required.
When we use initial regimens that include thalidomide or lenalidomide, we must be cautious not to extend the induction therapy because we may have difficulty collecting enough stem cells.
Bortezomib-based regimens have less impact on stem cell collection. In the context of our current treatment algorithm, which incorporates transplant and potentially tandem transplant, collecting enough stem cells for tandem transplant is clinically important.
On average, most studies will have seven to nine million stem cells collected, which is barely enough for one stem cell transplant, much less a tandem transplant. If you reduce the number of stem cells collected, you may end up not being able to deliver two transplants for patients who may have indication for a second transplant.
My operational adjustment is that I’m more careful not to extend the initial period with patients who are on a thalidomide-based regimen or a lenalidomide-based regimen, and I try to mobilize them earlier than I would normally.
With a bortezomib-based regimen, I don’t have to be that concerned because I know that if I am seeing a continuous response to therapy, for instance, I keep going until I reach plateau, so I have less contamination of collections with myeloma cells and there is improvement in some outcomes. Some people agree that that’s important. Others who are not sure whether they will go for transplant anticipate that the patient may receive treatment longer, and they will wait to see whether the patient’s performance status improves.
In that setting I would likely favor a bortezomib-based rather than a thalidomide-based regimen because I could give the patient’s performance status more time to recover, so he or she could be a more acceptable candidate for transplant.
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