There are several treatment protocols for Waldenstrom's macroglobulinemia involving the use (either alone or in combination) of alkylating agents, nucleoside analogues, and Rituximab. Also, Rituximab can be given in combination with the chemotherapy CHOP (Cyclophosphamide, Doxorubicin, Vincristine, Prednisone) or cyclophosphamide.
Stem cell transplant is also a feasible alternative, though data is limited to case reports and case series. This is an abstract on stem cell transplant as treatment for Waldenstrom's macroglobulinemia:
"Preliminary evidence suggests that high-dose chemotherapy followed by autologous or allogeneic stem cell transplantation may be effective in some patients with resistant Waldenstrom's macroglobulinemia. During the last 10 years, seven patients with Waldenstrom's macroglobulinemia have received transplants at the MD Anderson Cancer Center, four with autologous and three with allogeneic stem cells. Four patients achieved partial remission, and three patients have remained alive for at least 2 years. Our data confirm the feasibility of high-dose therapy in patients with macroglobulinemia and support the need for prospective studies of this modality in patients with chemosensitive disease." - Anagnostopoulos A, Dimopoulos, MA, et al. High-dose chemotherapy followed by stem cell transplant in patients with resistant Waldenstrom's macrogolulinemia. Bone Marrow Transplant. 2001 May; (27(10):1027-9.
Hope this helps.