Drug therapy of leukemia
Treatment of acute leukemia is principally chemotherapy to reduce or, optimally, to remove all leukemic clones.
For chronic myeloid leukemia, there is consensus that newly diagnosed patients in most situations should be given imatinib as the first choice of treatment. The observation time is limited for tyrosine kinase inhibitors, and treatment with an allogeneic stem cell transplantation is documented to cure the disease. New second-generation tyrosine kinase inhibitors are already registered and third-generation tyrosine kinase inhibitors are under development. Transplantation methods are also under development and new data from clinical studies are accumulating quickly. Algorithms for treatment and reponse evaluation are under continual change.
It is recommended that treatment of CML patients is done in cooperation with a university hospital.
In chronic lymphoblastic leukemia, there is no clear evidence that disease-directed treatment can prolong survival. Drug therapy is given to reduce symptoms.
Allogeneic stem cell transplantation
Up to 70% of adult patients below 40 years with acute myeloid leukemia, who are in their first remission with chemotherapy, can be cured by an allogeneic stem cell transplantation from an HLA-identical sibling donor after bone marrow eradication treatment. The transplantation is used as consolidation treatment instead of regular chemotherapy. But in patients aged over 40, the results are somewhat poorer.
For leukemia in more advanced phases, (accelerated phase of chronic myeloid leukemia, other remission or start of recurrence of acute leukemia) the possibility for curing the disease is less (< 40 %). If the disease is more advanced, the chance of curing the disease is under 10–15%.
Fatal complications occur in larger groups in at least 20–30%, usually within a few months, and increase with age and more advanced illnesses. They are more frequent with unrelated donors than for identical tissue types from sibling donors.
For acute lymphoblastic leukemia among adults, 5 year recurrence-free survival is achieved in up to 35% with modern chemotherapy. The results are better in younger patients compared to older patients. At most treatment centers, a first remission is treated by an allogeneic stem cell transplantation only in high risk patients. Adults cannot be cured with chemotherapy alone after recurrence of acute leukemia. However, with bone marrow eradicating treatment and allogeneic stem cell transplantations with HLA-identical stem cells, the disease is cured in 20-30%.
Differences between non-myeloablative and myloablative allogeneic stem cell transplant
During non-myeloablative stem cell transplantations, serious bone marrow depression, mucosal damage, and other organ toxicity following conditioning are usually avoided. In return, the patient receives a powerful immunosuppressive treatment. It is therefore necessary to be as aware of opportunistic infections as for a myeloablative transplant, but it will often develop later in the disease course.
Futhermore, the disease course for graft-versus-host disease (GVHD) will be different since acute GVHD often occurs also after 100 days, during or after a gradual reduction of immunosuppression. Treatment may be necessary.
GVHD often occurs when the patient converts from mixed to full chimera status of T-cells.