Bortezomib and cyclophosphamide in combination with dexamethasone has already demonstrated high response rates in refractory multiple myeloma. Low dose continuous cyclophosphamide, also called metronomic scheduling, minimize toxic side effects and eliminate the obligatory rest periods. Combining cyclophosphamide with bortezomib might target distinct aspects of a myeloma functionality.

The objectives of the present study are whether patients with refractory or relapsed multiple myeloma after reinduction with bortezomib, cyclophosphamide and dexamethasone will benefit from maintenance therapy with bortezomib and cyclophosphamide with acceptable side-effects. Recently two studies have shown with thalidomide that maintenance therapy might improve EFS and one study also the OS.

Inclusion Criteria:

• Age ≥ 18 years
• Stage II-III Multiple Myeloma
• Relapse or primary refractory disease after initial chemotherapy
• WHO performance status 0 - 2
• Life expectancy of at least 6 weeks
• ANC (absolute neutrophil count) ≥ 1.0x109/l(or ≥ 0.5x109/l, if due to bone marrow infiltration by malignancy)
• Platelet count ≥ 75x109/l or ≥ 50x109/l, if due to bone marrow infiltration by malignancy)
• Written informed consent (present in patient's file)
• Patient is able and willing to use adequate contraception during therapy and for at least 1 month after study
• Patient has the ability to understand the requirements of the study

Exclusion Criteria:

• Previous treatment with bortezomib
• Urine production < 1.5 l/24h
• Pre-existent polyneuropathy (grade 2 or higher, according to CTCAE 3.0)
• Pregnancy or positive pregnancy tests during study and for 1 month after final dose of thalidomide
• History of active malignancy during the past 5 years with the exception of basal carcinoma of the skin)
• Active uncontrolled infections
• Additional uncontrolled serious medical or psychiatric illness