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A B S T R A C T PurposeTo assess efficacy and safety of single-agent bortezomib in previously untreated patients with multiple myeloma, investigate prevalence of baseline and treatment-emergent polyneuropathy, and identify molecular markers associated with response and neuropathy. Patients and MethodsPatients received bortezomib 1.3 mg/m 2 on days 1, 4, 8, and 11, for up to eight 21-day cycles. A subset of patients underwent neurophysiologic evaluation pre-and post-treatment. Bone marrow aspirates were performed at baseline for exploratory whole-genome analyses. ResultsAmong 64 patients, 41% had partial response or better, including 9% complete/near-complete responses; median duration of response was 8.4 months. Response rates did not differ in the presence or absence of adverse cytogenetics. After median follow-up of 29 months, median time to progression was 17.3 months. Median overall survival had not been reached; estimated 1-year survival was 92%. Thirty-two patients successfully underwent optional stem-cell transplantation. Bortezomib treatment was generally well tolerated. At baseline, 20% of patients had sensory polyneuropathy. Sensory polyneuropathy developed during treatment in 64% of patients (grade 3 in 3%), but proved manageable and resolved in 85% within a median of 98 days. Neurologic examination, neurophysiologic testing, and measurements of epidermal nerve fiber densities in 35 patients confirmed pretreatment sensory neuropathy in 20% and new or worsening neuropathy in 63%. Pharmacogenomic analyses identified molecular markers of response and treatmentemergent neuropathy, which will require future study. ConclusionSingle-agent bortezomib is effective in previously untreated myeloma. Baseline myelomaassociated neuropathy seems more common than previously reported, and bortezomib-associated neuropathy, although a common toxicity, is reversible in most patients.

Prior studies have shown that myeloma patients exhibiting either genetically defined high-risk disease or plasma cell leukemia have a poor outcome with a median overall survival (OS) of ≤3 years. Results of IFM 2005-01 and 02 suggest that relatively limited bortezomib-containing induction regimens did not produce a major survival benefit among these patients. However, results of recent studies suggest that combination therapy may benefit these patients when given early and again later in the treatment. We evaluated a combination maintenance/consolidation regimen (RVD) following autologous stem cell transplant (ASCT) for high-risk patients to evaluate the impact of this approach on outcome. Following initiation of RVD maintenance, 51% of patients achieved stringent complete response (sCR), with 96% achieving at least VGPR as best response. Median progression free survival (PFS) for all patients is 32 months with a 3-year OS of 93%. The regimen was well tolerated with no grade 3/4 neuropathy. Early ASCT followed by RVD maintenance is a promising strategy for high-risk myeloma patients and delivered excellent response rates, and promising PFS and OS.