PGP and spinal cord neoplasm: To evaluate the suicide effect of PgP/pHSV-TK with GCV treatment, PgP/pHSV-TK polyplexes at an N/P ratio 60/1 (10 μg pHSV-TK) were injected into spinal cord tumors at 5 days post-injection of C6 cells and then received i.p. injection of 40 mg GCV/kg for 10 days.