The three drugs combination of cyclophosphamide, bortezomib and dexamethasone (CyBorD) has been proven to be a powerful regimen for the treatment of the patients with multiple myeloma (MM). However, twice-weekly schedule of bortezomib and high dose dexamethasone has been shown to cause significant toxicities, including severe peripheral neuropathy (PN). Recently, once-weekly bortezomib induction therapy with CyBorD (modified-CyBorD) has shown less toxicity with high response rate equal to original regimen (Reeder, CB et al. Leukemia 2009). However, more than half of the patients developed bortezomib induced PN (BiPN) in modified-CyBorD. Thus it was still concerned adverse event for the transplant ineligible patients, especially frail elderly patients because it often caused interruption or withdrawal of the treatments, resulting in fewer efficacies. Under these circumstances, we introduced the reduced-dosage of CyBorD regimen (reduced-CyBorD) in the transplant ineligible patients with multiple myeloma for continuation of the treatment.

The protocol consisted of bortezomib given intravenously at a dose of 1.3 mg/m²once a week on days 1, 8, 15, cyclophosphamide orally at a dose of 50 mg daily on days 1–21, and dexamethasone orally or intravenously at a dose of 20 mg daily on days 1,2,8,9,15,16 in 4-week cycles. Total of 20 patients, including 12 newly diagnosed and 8 refractory, were treated with reduced-CyBorD and evaluated its efficacy and safety.

The median age was 72 years (range from 62 to 81). 14 patients were more than 70 year-old (70%). A half of the patients were female. According ISS, 3 patients were classified in stage I, 6 were in II, and 11 were in III. The overall response was 86.6 % with 26.7 % CR/nCR (1 CR, 3 nCR, 5 VGPR and 4 PR). Hematological adverse events were neutropenia (35%; G1/2 n=7), lymphocytopenia (35%; G1/2 n=1, G3/4, n=1), thrombocytopenia (10%; G1/2 n=2). Non-hematological adverse events were pneumonia (20%; G2 n=2, G3 n=2), VZV infection (15%; G2 n=3), cerebral infarction (5%; G2 n=1). Importantly, only three patients (15%) developed grade 1 PN, and no patient reduced or discontinued bortezomib due to PN.

Reduced-CyBorD with three times once-weekly bortezomib retained high efficacy seen in standard and modified CyBorD (4 times bortezomib administration). Furthermore, it was found that this regimen obviously revealed less toxicity, especially BiPN compared with those previous regimens (See Table). Our results suggested that reduced-CyBorD might be safe and effective approach to the transplant ineligible patients, especially elderly frail patients with MM.

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No relevant conflicts of interest to declare.