The origin of 6 isologously transplantable leukemias in Fischer/344 rats is described. Three of these are considered acute (R 3149, R 3323, and IRC 741) with different biologic characteristics, 1 is subacute (R 3330), and 2 (R 3399 and R 3432) are considered chronic. The responses of 5 of these transplanted leukemias to 11 standard steroid compounds were compared. R 3323 proved to be the most responsive to the estrogens. R 3149, R 3323, and R 3330 responded to some of the corticoids, and IRC 741 was refractory to all of the standard steroids. R 3399 showed some response to stilbestrol (NSC-3070), estradiol (NSC-9895), progesterone (NSC-9704), and testosterone (NSC-9700) but was refractory to the corticoid compounds. Incomplete tests with the other chronic leukemia, R 3432, showed it to be refractory to stilbestrol, estradiol, testosterone propionate (NSC-9166), and cortisone (NSC-9703).

The 108 selected compounds tested included 33 estrogens, 16 androgens, 20 progestogens, 16 corticoids, 5 flavanoids, and 8 miscellaneous compounds. R 3323 had a good response to 9 estrogens, 7 progestogens, and 12 corticoids. R 3149 responded well to 7 progestogens and 8 corticoids. R 3330 responded to 3 estrogens, 5 progestogens, and 8 corticoid compounds. R 3399 was not tested with any estrogens but failed to respond to the 4 progestogens and 4 corticoids that were effective against the acute leukemias. The effectiveness of certain progestogens, corticoids, and estrogens suggests the desirability of correlating chemical structure with antitumor activity.


Supported by contract PH-43-64-80 from the Cancer Chemotherapy National Service Center, National Cancer Institute, USPHS.

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