Vaccine therapies for non-Hodgkin's lymphoma.

Various clinical observations suggest that non-Hodgkin's lymphomas (NHLs), particularly those of low histologic grade, can be controlled by immunologic mechanisms. Although many effective therapies exist for the initial treatment of low grade lymphomas, none are curative and most have significant toxic side effects. Several promising lymphoma tumor antigen vaccines are being studied at medical centers throughout North America. I favor the scientific evaluation of a therapeutic strategy for follicular NHL that places immune-based therapies forward in the treatment algorithm to the initial therapeutic decision point. Active immunotherapies (therapeutic tumor vaccines) are instituted in tandem with initial cytoreductive chemotherapy, and followed by passive monoclonal antibody therapies. The tumor-specific idiotype vaccines are favored because of their demonstrated potential for clinical activity in numerous human studies and their lack of significant toxic side effects. Rituximab and other monoclonal antibodies directed at normal B-cell antigens are known to abrogate the host's ability to mount primary humoral immune responses, including antitumor antibodies evoked by tumor vaccines. Therefore, one should consider deferring the use of these agents until after an attempt at generating a host humoral antitumor response using investigational tumor vaccines. Chemotherapy regimens containing highly immunosuppressive agents (ie, fludarabine) or organ dose-limiting toxicities (ie, doxorubicin) may be best reserved for later in the disease course for those failing the more conservative approaches and for cases with adverse prognostic features. This strategy may give patients the greatest chance at prolonged remission or cure while minimizing acute and chronic toxicities, although its impact on overall survival has not been proven. Low grade NHLs remain the proving ground for this treatment philosophy. Hopefully, in the future, similar strategies may be applicable to NHLs of other grades and histologies.