Ara-G is an analog of the nucleoside guanosine and an active metabolite of nelarabine .1,2 Ara-G accumulates in T lymphoblasts and malignant T-lymphoid cells, where it is phosphorylated to produce ara-GTP and incorporated into the DNA.3,1 Ara-G inhibits DNA replication by 92% after 30 minutes when used at a concentration of 50 μM in CEM cells, which are used as a model for human T lymphoblasts.1 It also halts the cell cycle at the sub-G1 phase and induces apoptosis in CEM cells.3 Syngeneic bone marrow containing 6C3HED tumor cells treated with ara-G (100 mM) ex vivo prior to transplantation increases survival of lethally irradiated mice and induces reconstitution of lymphoid, myeloid, and erythroid cell linages.4

References
1. Leanza, L., Miazzi, C., Ferraro, P., et al. Activation of guanine-β-D-arabinofuranoside and deoxyguanosine to triphosphates by a common pathway blocks T lymphoblasts at different checkpoints. Exp. Cell Res. 316(20), 3443-3453 (2010).
2. Lambe, C.U., Averett, D.R., Paff, M.T., et al. 2-Amino-6-methoxypurine arabinoside: An agent for T-cell malignancies. Cancer Res. 55(15), 3352-3356 (1995).
3. Rodriguez, C.O., Jr., Stellrecht, C.M., and Gandhi, V. Mechanisms for T-cell selective cytotoxicity of arabinosylguanine. Blood 102(5), 1842-1848 (2003).
4. Kurtzberg, J. Guanine arabinoside as a bone marrow-purging agent. Ann. N.Y. Acad. Sci 685(1), 225-236 (1993).