A new basis for treatment of multiple myeloma.

In order to get a better understanding of tumor biology, prognostic factors and approaches to treatment, total body tumor cell number, cell kinetics and drug sensitivity have been studied in a series of patients with multiple myeloma. We found that the presenting tumor mass stage was inversely proportional to survival, but did not predict drug sensitivity. Patients with both a high tumor cell mass and a large proliferative compartment of tumor cells had a particularly poor prognosis. Studies of myeloma stem cells in agar culture showed individual patterns of drug sensitivity with a correlation between in vitro sensitivity to melphalan, adriamycin, and BCNU, with in vivo sensitivity to these same classes of agents. Use of such measurements may permit selection of useful new drugs as well as an individualized basis for treatment of multiple myeloma.