Effects of 5,8-dideazaisofolic acid (IAHQ) on human tumor cells in culture and on normal and tumor-bearing hamsters.

The quinazoline analog of folic acid, 5,8-dideazaisofolic acid (IAHQ), was tested for its effects on the growth of human tumor cells in vitro and in vivo. Of 23 human tumor cell lines tested in vitro, 7 were inhibited by IAHQ (ED50, 5 X 10(-6) to 5 X 10(-7) M). For in vivo studies, human osteosarcoma (OS) cells from the IAHQ-sensitive line TE-85 were implanted intraperitoneally in newborn hamsters: in the group treated with IAHQ, only 30% of the animals developed OS, compared with 100% of those not treated with IAHQ. The effects of IAHQ injections on mitogenic responses and natural killer activity of lymphocytes from normal 3-month-old hamsters were also examined.