- Avoidance of bone marrow suppression using A-5021 as a nucleoside analog for retrovirus-mediated herpes simplex virus type I thymidine kinase gene therapy. Hasegawa, Y., Nishiyama, Y., Imaizumi, K., Ono, N., Kinoshita, T., Hatano, S., Saito, H., Shimokata, K. Cancer Gene Ther. (2000)