CAR-T therapy first showed success in CLL and AML leukaemias, but one of the problems with CAR-T is that the T-cells are not selective against cancerous lymphocytes, so they keep killing off both cancerous and non-cancerous lymphocytes long after treatment initiation. For CLL patients, that means long term infusions of IVIG are needed, which is an expensive therapy. Novartis have made progress in limiting the active period of the CAR-T cells with AML therapy in mice studies, as is reported in this Hematology Times article (free registration required):
There's another reason for limiting the lifetime of the CAR-T therapy - using it to prepare a patient for allogeneic bone marrow transplant: 'Allogeneic transplantation is the only potentially curative option in relapsed/refractory AML,” Dr Kenderian noted. “Outcomes are poor if patients are transplanted in residual disease . . . , and these patients are often considered transplant-ineligible. Therefore, novel therapies are desperately needed.”' The same can be said for CLL patients.
Incidentally, one of the patients on the CAR-T CLL trial in 2013 recently reported on another CLL forum that his blood work is all normal (including lymphocytes) and he continues to have IVIG every 10-12 weeks.