An analysis of which subgroups of multiple myeloma patients, divided according to b(2)-microglobulin and plasma cell labeling index, benefit from high dose vs conventional chemotherapy.

The clinical advantage of high-dose therapy (HDT) over standard treatment for multiple myeloma (MM) patients has been recently assessed. Which patient subgroups benefit most from this approach is unclear.To address this issue, the outcome of 54 patients under 55 years old treated with HDT was compared with that of 101 age-matched controls selected from 390 patients who received standard melphalan and prednisone (MP) chemotherapy in a national multi-center trial (M90 protocol).The complete response (CR) rate was 50% in the HDT group compared to 5% in the MP group. Event-free survival (EFS) was three times longer for the HDT patients (median 34.5 vs 12.2 months, p<0. 0001), though the controls enjoyed a prolonged survival after relapse, and hence there was no statistically significant difference in OS. Overall survival (OS) was analyzed in relation to to two major prognostic factors: b(2)-microglobulin (b(2)-M) and bone marrow plasma cell labeling index (LI). HDT significantly improved OS in poor prognosis patients with a high LI (>1.2%), (median 49.5 vs 32.5 months, p<0.03), whereas it did not prolong OS in poor prognosis patients with high b(2 )-M (> 3 mg/L).In conclusion, HDT has a major impact on CR and EFS, and is the treatment of choice for patients with a high LI. Alternative strategies should be adopted in poor prognosis patients with high b(2 )-M.