Bortezomib therapy alone and in combination with dexamethasone for previously untreated symptomatic multiple myeloma.

Bortezomib, as a single agent and in combination with dexamethasone, was examined as first-line treatment in 32 consecutive patients with untreated symptomatic multiple myeloma. Patients received bortezomib 1.3 mg/m(2) for a maximum of six 3-week cycles; oral dexamethasone 40 mg was added if a less than partial response (PR) was achieved after two cycles or a less than complete response (CR) was achieved after four cycles. The response rate (CR + PR) was 88%, with undetectable paraprotein (CR) in 6%, and detectable by immunofixation only in 19% [near (n)CR]. All 32 patients completed the first two cycles of bortezomib alone, of whom 3% achieved CR, 9% nCR, and 28% PR. Ten patients received single-agent bortezomib on study, and dexamethasone was added in 22, leading to 15 improved responses. The most common adverse events >/=grade 2 included sensory neuropathy (31%), constipation (28%), myalgia (28%) and fatigue (25%). Sensory neuropathy grade 2 or 3 was reversible within a median of 3 months in five of 10 patients. Bortezomib treatment did not affect stem cell mobilization in eight or transplantation in six patients. Bortezomib alone or in combination with dexamethasone is an effective induction therapy with a high CR and nCR rate and manageable toxicities in previously untreated patients with myeloma.