Lay Summary: Induction regimens for high dose chemotherapy have not been sufficiently compared but this should not lead us to concluding that they are experimental.
High-dose therapy with autologous stem cell transplantation (ASCT) has been extensively used in the past 15 years in multiple myeloma. Several randomized studies confirm that ASCT yields superior complete remission and event free survival rates. However what the field is missing is trials comparing various induction regimens one to another in terms of effectiveness. Several such regimens are being employed without experimental confirmation that they are equivalent or superior to others.
The goal of induction therapy is to reduce the tumor burden prior to high-dose therapy and autologous transplant. Many groups have used administration of 2 to 4 cycles of VAD for this purpose. VAD has the important advantage of sparing hematopoietic stem cells relative to other chemotherapeutic regimens, particularly combinations of alkylating agents. This increases the likelihood that sufficient autologous stem cells can be collected for transplantation. Other induction regimens that may also be useful for reducing the tumor burden and sparing stem cells include administration of 2 or more cycles of dexamethasone either alone or with thalidomide, CDEP VDT-PACE, PACE and others. Currently, the optimal induction regimen and number of cycles of treatment are unclear. Further studies are underway to clarify this issue.
Despite this fact, I do nto consider it sufficient to deny autologous transplantation, which is generally agreed by experts to be standard of care and is enshrined in guidelines. It would be paradoxic to allow transplants as standard of care but in practice not approving any transplant because the induction regimens are not comparatively studied.
Jean-Luc Harousseau, Michel Attal The role of stem cell transplantation in multiple myeloma Blood Reviews, Volume 16, Issue 4, Pages 245-253 (December 2002)
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Sonneveld P, Segeren CM. Changing concepts in multiple myeloma: from conventional chemotherapy high-dose treatment. Eur J Cancer. 2003;39:9-18.