The purpose of this study is to assess the effectiveness of the drug bortezomib in treating patients with relapsed or refractory indolent B-cell lymphoproliferative disorders or mantle cell lymphoma when it is combined with other drugs now being used to treat these diseases (rituximab, cyclophosphamide, and prednisone).
Bortezomib is a new drug that has been approved by the FDA for use in patients with a cancer of the bone marrow called multiple myeloma. This drug is thought to inhibit many proteins (known as proteasomes) that cancer cells need to survive and multiply.
In the phase I portion of this study, researchers will determine the highest dose of bortezomib and cyclophosphamide that can be given to these patients. In the phase II portion, they will determine how active this combination of drugs is in treating the various kinds of lymphoma.