Beta₂-microglobulin and bone marrow plasma cell involvement predict complete responders among patients undergoing blood cell transplantation for myeloma

We studied the prognostic value of clinical and laboratory variables, measured before blood cell transplantation, in predicting complete response among patients undergoing autologous blood cell transplantation for relapsed or primary refractory myeloma. Sixty-seven patients who underwent transplantation for relapsed or primary refractory myeloma were studied. The overall response rate was 90%, and the complete response rate was 33%. Low β₂-microglobulin (≤ 2.7 mg/l) was associated with a significantly better complete response rate compared with high levels (54 vs 19%, P = 0.002). Similarly, the complete response rate was 39% when the bone marrow plasma cell percentage was low (< 40%) and 21% with greater involvement (P = 0.04). Complete response rate was 50% when β₂-microglobulin and bone marrow plasma cell percentage were low, 36% if either was high, and 12% when both were high (P = 0.01). Median survival measured from initial diagnosis of myeloma was 51 months. Overall survival after transplantation was better among responders who achieved complete response than those who did not: median survival, 24 vs 11 months, P = 0.04 (log-rank) and 0.009 (Gehan-Wilcoxon). Attainment of a complete response independently predicted better survival in a multivariate analysis. β₂-Microglobulin and bone marrow plasma cell percentage predict complete responders among patients undergoing transplantation for myeloma.