Factors predictive of outcome in relapsed, refractory multiple myeloma patients treated with bortezomib, melphalan, prednisone, and thalidomide (VMPT)

Abstract

8048 Background: In relapsed/refractory multiple myeloma (MM) patients, the addition of thalidomide and bortezomib to the standard oral melphalan/prednisone (VMPT) significantly increased response rate and progression-free survival (PFS) (Blood. 2006 Dec 5; [Epub ahead of print]). Baseline parameters which may predict outcome after VMPT have been investigated to identify which patient subgroups most benefit from this drug combination. Methods: Thirty patients with relapsed or refractory MM after 1 or 2 lines of treatment, were treated with six 35-days courses of bortezomib (3 dose levels: 1.0,1.3 and 1.6 mg/m2) on days 1,4,15,22, plus melphalan (6 mg/m2) and prednisone (60 mg/m2) on days 1–5 and thalidomide (50 mg) on days 1–35. Several parameters such as age, β2-microglobulin, C-reactive protein, chromosome 13 abnormalities, albumin, haemoglobin, stage, creatinine, bone marrow plasmacytosis, line of therapy and dosage of bortezomib were analyzed in association with response rate and PFS, using χ2 and Cox model. Results: At least a very good partial response was achieved in 43% of patients and at least a partial response in 67%. The 1-year PFS was 61%, and the 1- year overall survival was 84%. Subgroup analyses did not show any statistical difference between responses and either age, β2 microglobulin, C-reactive protein, chromosome 13 abnormalities, line of treatment or dosage of bortezomib. Serum albumin <3.5 mg/dL was loosely associated with a lower response rate (p=0.09). Factors predictive of shorter PFS were C-reactive protein = 6 mg/L (p=0.02) and 3rd line of therapy (p=0.009). Factors loosely associated with shorter PFS were β2-microglobulin = 3.5 mg/L (p=0.06) and creatinine = 2 mg/dL (p=0.09). No difference in PFS was observed between patients with or without chromosome 13 abnormalities. Conclusions: VMPT induced a high proportion of responses and appeared to overcome the poor prognosis of patients with chromosome 13q deletion. [Table: see text]