The Oncologic Drugs Advisory Committee (ODAC) to the United States Food and Drug Administration has recommended GlaxoSmithKline's accelerated approval of Arranon (nelarabine) Injection, a chemotherapy agent. GSK is seeking approval in the United States of Arranon for the treatment of T-cell acute lymphoblastic leukaemia (T-ALL) and T-cell lymphoblastic lymphoma (T-LBL) in paediatric and adult patients whose disease has not responded to or has relapsed following treatment with at least two chemotherapy regimens.

Discovered by GSK, Arranon is a water-soluble prodrug of ara-G with T-cell selectivity. Arranon has been studied in collaboration with the National Cancer Institute (NCI) of the National Institutes of Health (NIH), the Children's Oncology Group (COG) and the Cancer and Leukaemia Group B (CALGB), in conjunction with the Southwest Oncology Group (SWOG). Throughout the development of the compound, more than 980 patients have been treated with Arranon. The clinical studies were sponsored by the Cancer Therapy Evaluation Program of the NCI under a Clinical Trials Agreement between GSK and the NCI.

In December 2003, the FDA granted Arranon Fast Track designation, conferred on products in development that demonstrate a potential to address an unmet medical need for a serious or life-threatening condition. The FDA later granted Arranon Orphan Drug Status, a designation given to products under development for a rare disease or condition (i.e. affecting fewer than 200,000 people per year in the US). It is estimated that 1,600 adults and children are diagnosed in the United States every year with these rare cancers, T-ALL and T-LBL.

Acute lymphoblastic leukaemia (ALL) is a cancer of the white blood cells, the cells in the body that normally fight infections. It is an aggressive disease that is more common in children and progresses rapidly in the absence of effective therapy. ALL is the most common cancer in children, representing 23 percent of cancer diagnoses among children younger than 15 years of age. T-ALL patients tend to have a poor prognosis and represent a subset of the ALL population.

Lymphoblastic lymphoma (LBL) is a type of non-Hodgkin's lymphoma (NHL), a cancer of the lymphatic system, which occurs more often in children than adults. T-LBL patients represent a subset of this population.