 Rituximab has also been used in small numbers of patients in combination with thalidomide with some effect.In contrast to these antibody-based 'passive' immunotherapies, the field of 'active' immunotherapy tries to activate a patient's immune system to specifically eliminate their own tumor cells.Examples of active immunotherapy include cancer vaccines, adoptive cell transfer, and immunotransplant, which combines vaccination and autologous stem cell transplant.