Leukemia is a group of malignant disorders of the hematopoietic tissues characteristically associated with increased numbers of white cells in the bone marrow and or peripheral blood.

This type of cancer can be classified into:-
1. Acute : ALL (Acute Lymphoblastic Leukemia ) and AML (Acute Myeloid Leukemia)
2. Chronic : CLL(Chronic Lymphoblastic Leukemia ) and CML (Chronic Myeloid Leukemia)

The malignant transformation of a myeloid precursor cell usually occurs at a very early stage of myeloid development. This is rare in childhood stage and the chances of occurrence of the disease increases with age. Presently, there are around 5% of all new cancer cases. The acute myeloid leukemia (AML) is common among adults and acute lymphoblastic leukemia (ALL) is prevalent among children. The ionizing radiation, chemical compound benzene, chemotheraputic agent like, alkylating agent, topoisomerase II inhibitor are generally used for the treatment. The virus Human T-lymphocyte leukemia virus (HTLV1) results in congenital disorder like, Down syndrome, Immunodeficiency syndrome, etc.

The prominent signs and symptoms for the disease are as mentioned below:
i) Pancytopenia: The low count WBC causing infection. The depreciating level of hemoglobin results in anemia and low platelets can cause heavy bleeding, thrombocytopenia
ii) Organ infiltration: Lymphadenopathy, Splenomegally, Hepatomegally.

There are chances of median survival without treatment for 5 weeks. There are 30% survival chances for youger patients suffering with leukemia for abot 5 years with chemotherapy. The disease which relapses during treatment or soon after the end of treatment has a poor prognosis.

Recently, the clinical trial was done on acute leukemia patients. The genetically engineered immune cells were used as the investigational product (IP). The clinical trial suggests that the genetically engineered immune cells that can treat an acute type of leukaemia. The trial was experimented on five patients with acute lymphoblastic leukemia (ALL). The recent results of the trial were published in the journal Science Translational Medicine. This represent the latest success for a 'fringe' therapy in which a type of immune cell called T cells are extracted from a patient, genetically modified, and then reinfused back into the patient. In this case, the T cells were engineered to express a receptor for a protein on other immune cells, known as B cells, found in both healthy and cancerous tissue. When reintroduced into the patients, the tricked T cells quickly hit their original targets.

The technique has already shown good result against chronic leukaemia, but there were doubts regarding that whether it could work on the faster-growing and lethal acute lymphoblastic leukaemia, a tenacious disease that kills more than 60% of those afflicted with the same.

Another month in the hospital on intensive chemotherapy drugs did nothing to help. By the time the subject entered the trial, 70% of his bone marrow had become cancerous. The investigators and researchers then extracted T cells from the patient and engineered them to express a chimeric antigen receptor (CAR), that would target cells expressing a protein called CD19. As CD19 is found on both healthy and cancerous B cells, the engineered T cells were unable to discriminate between the two. However, the patients can still survive without B cells.
After the procedure was over, the patient was showing signs of improvement. The treatment had driven the cancer into the remission. Thus, the patients became eligible for a bone-marrow transplant. They were checked after certain period of time. Many of the patients were well enough to receive the transplant and the remaining of them relapsed as they were found ineligible.

Pharmaceutical firms have tended to be the wary of the CAR technique because it is technically challenging, must be personalized to the patient and faces an untested path to regulatory approval. But this seems to be changing. The trial was made multi-centric to test whether the technique can be exported to other treatment centers to find other outcomes.

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Geetanjali Murari
Emai Id: geetanjali1232@gmail.com