Total Skeletal Irradiation in Multiple Myeloma Before Second Autologous Hematopoietic Stem Cell Transplantation

The purpose of this study is to improve the efficacy of the HDC regimen by adding a novel, "targeted" means administering a variation of total body irradiation (TBI) radiation i.e., total skeletal irradiation (TSI) administered by helical tomotherapy (HT) before, and in addition to the current standard of HDC, at a dose of 200 mg/m2 (HDMel200). The underlying postulate of this endeavor is that TSI-HT will provide additional cytoreduction to HDMel alone, without producing additional (serious) toxicity. We will utilize a classical Phase I study design (i.e., dose escalation) in myeloma patients undergoing AHSCT2 to define a maximum tolerated dose (MTD) and dose limiting toxicity (DLT). Finally, although comparisons to other therapies are not typical (and/or feasible) for a Phase I study, we will compare, whenever possible, both the toxicity and the antimyeloma activity of the AHSCT2 to AHSCT1. This protocol will standardize, as much as possible the use of AHSCT2 both as a "tandem" and "salvage" procedure. Since sufficient AHSC (CD34+ cells) are routinely collected in adequate numbers for multiple AHSCTs, but recently used infrequently, it is important to work towards defining the optimal utilization of this resource.