Immunotherapy has emerged as effective treatment for patients with Blood Cancer states Dr Sharat Damodar, Narayana Health City

There are 2 types of blood cancers - acute leukemia and chronic leukemias. Acute leukemia can be lymphoid or myeloid. With the progress in various chemotherapy regimens the cure rate in pediatric acute lymphatic leukemia has been as high as 80 to 90 per cent in western literature, but the numbers are lower in our country, it is around 60 to 80 per cent. There are various reason for this starting from delay in diagnosis, to higher infection rates to disease biology and pharmacogenetics. However, acute myeloid leukemia has lower cure rates with chemotherapy alone and a large subset of these patients need a bone marrow transplant as a curative treatment option.

BMT was not easily available in our country 10 years ago, but now there are more than 100 transplant centers in the country who can offer this treatment. BMT needs a donor to donate the stem cells and generally, siblings tend to be the fully matched HLA eligible to donate. However, not all patients would have fully matched sibling donors and hence medical science started looking for other donor options. The stem cell registries were set up and they were able to offer the option of unrelated matching stem cell donors. Adults between the age group of 18 to 60 years can enroll in these registries voluntarily and donate stem cells when needed. The Indian registry called DATRI currently has around 5 lac donors which is grossly inadequate for our country. We certainly need more people to volunteer as donors. Due to the non-availability of unrelated fully matched donors the next option was to use a half-matched parent, child or sibling called a haplo transplant and this is the new therapy for leukemias who need BMT as a curative treatment option.

However, in spite of all these advances, there are patients who cannot undergo a BMT or relapse after BMT. The real-world experience of this is Emily Whitehead, a child in the US, who relapsed with leukemia after BMT in 2012, and became the first patient to receive immunotherapy - CAR T Cell Therapy. There are various types of immunotherapy like monoclonal antibodies and T cells. The monoclonal antibodies are antibodies that target the antigens on the cancer cells. This is like sniper shooting compared to the carpet bombing of chemotherapy.

The world is moving towards these kinds of treatment in cancer. Emily is free of disease for the last 10 years and has been called cured. Similar results in chronic lymphatic leukemia in adults is also available with 2 patients who have crossed 10 years from treatment and been declared cured. In CAR T cell therapy, T cell are collected from the patient and a receptor is expressed on the cells using a viral vector, after which the cells are reinfused back to the patient, wherein these cells go and bind to the cancer cells and destroy them. This kind of therapy has known to produce long term cures in leukemia, lymphoma and myeloma. Till recently, this therapy was available only in the US, Europe and China at an exorbitant cost of 4 crore, however, the efforts and expertise of our physicians has ensured the treatment is made available in India as well.

- By Dr Sharat Damodar, Clinical Director and Head of adult haematology/BMT/Immunotherapy Mazumdar Shaw Cancer Center, Narayana Health City Bangalore.

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