HIGH PROPORTIONS OF VLA-5(-) IMMATURE MYELOMA CELLS CORRELATED WELL WITH POOR RESPONSE TO TREATMENT IN MULTIPLE-MYELOMA

Using two-colour phenotypic analysis with anti-CD38 antibody, human my eloma cells can be classified into VLA-5(-) immature and VLA-5(+) matu re cells. We examined the relationship between variations of these sub populations and clinical responses during treatment in multiple myelom a (MM), 39 patients with MM were treated with combined chemotherapy. F irst estimation of clinical responses after induction therapy showed t hat early clinical responses were correlated with the percentage of im mature myeloma cells present after induction therapy (P < 0.01), not a t diagnosis, After three courses of cyclic maintenance therapy, immatu re myeloma cells significantly decreased in proportion along with a de crease in total myeloma cells in maintained or more responsive cases ( P < 0.01), On the other hand, immature myeloma cells were still found in high proportions in nonresponsive cases with no change (NC) or mino r response (MR) (P < 0.01), Furthermore, in relapsing cases from parti al response (PR) or progressive disease (PD) from nonresponsive cases, immature myeloma cells increased markedly. Therefore these results sh ow that high proportions of VLA-5(-) immature myeloma cells remaining after induction therapy and during maintenance therapy correlate well with a declining clinical course of MM during maintenance therapy.