All participants will receive bortezomib as a fixed dose, which will not change unless any intolerable side effects occur. At the start of this study, 3 participants will be given a dose of bortezomib. If this dose does not cause intolerable side effects, the dose will be increased as new participants take part in this study. There will be a total of 3 groups (with 3-6 participants per group) entered at increasing dose levels. The dose of bortezomib you receive will depend on when you join this study.