Is flow cytometric DNA content hypodiploidy prognostic in multiple myeloma?

Hypodiploid multiple myeloma is uncommon when assessed by DNA content flow cytometry, having been reported in less than 6% of patients with newly diag nosed multiple myeloma. Previous studies have shown these patients to be un responsive to therapy and to have short survival. To address this further, we studied 349 of 504 patients eligible for Eastern Cooperative Oncology Gr oup (ECOG) treatment trial E9486 and laboratory correlative study E9487 who had marrow mononuclear cells available for ploidy analysis. Marrow samples were studied by dual channel flow cytometry, using propidium iodide to mea sure the DNA content and kappa and lambda light chain antisera to identify the clonal cells. A DNA index < 0.95 was considered hypodiploid. Five patie nts (1.4%) were found to have hypodiploid DNA content in their marrow plasm a cells. Three of the 5 patients with hypodiploid myeloma had a partial obj ective response to chemotherapy, which is not different from the overall ob jective response rate for all patients enrolled on E9486. All five patients with hypodiploid multiple myeloma died within 4 years from diagnosis, but these patients had a similar overall median survival (2.6 years) compared t o the patients with diploid DNA content. Our studies confirm the poorer sur vival of patients with diploid versus hyperdiploid myeloma; we cannot confi rm, however, the previously reported very poor outcome associated with hypo diploid myeloma using DNA content flow cytometry. Hypodiploid DNA content o f plasma cells by flow cytometry may not be as ominous a factor as previous ly reported.