Does [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine]- dichloroplatinum(II) act on the hormone-sensitive, murine breast cancer as a biological response modifier? Part II. Studies on the influence of [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine] dichloroplatinum(II) on the specific immune defense in MXT-M-3,2 breast cancer bearing mice

Does [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine] dichloroplatinum(II) act as an immune response modifier? IV. Inhibition of the proliferation-increasing effect of progressively growing MXT-M-3,2 breast cancer on phagocytes by the title compound

In female B6D2F1 mice bearing an MXT-M-3,2 breast cancer graft the level of the phagocytic cells (e.g. of granulocytes and macrophages in the spleen and of granulocytes and monocytes in the blood) is significantly elevated. The positive correlation between the number of the phagocytic cells and the weight of the tumor indicates that the MXT-M-3,2 breast cancer promotes myelopoiesis, presumably by secretion of hematopoietic growth factors like GM-CSF. This process can be described for each phagocyte type by a regression equation. Due to its hormonal potency [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine] dichloroplatinum(II) (meso-1-PtCl2) can reduce the excessive numbers of the granulocytes and macrophages, which seem to be responsible for the progressive growth of the MXT-M-3,2 breast cancer. This process leads to an interruption of the vicious circle of mutual growth stimulation of breast cancer cells and these phagocytes. The target of meso-1-PtCl2 is the estrogen receptor (ER) of the breast cancer cell. The interaction between meso-1-PtCl2 and the ER presumably results in a diminished secretion of hematopoietic growth factors and hence in a decline of the number of phagocytic cells. Meso-1-PtCl2 does not inhibit the proliferation of tumor cells by direct interaction with their DNA, as is described for platinum complexes like cDDP. In its mode of action the equipotent, breast cancer inhibiting drug cDDP differs from meso-1-PtCl2. This is obvious from the fact that in cDDP--but not in meso-1-PtCl2-treated, tumor bearing mice the number of granulocytes and macrophages does not markedly deviate from that in untreated control mice with tumors of the same weight. The drug cDDP probably does not interfere with the mechanism of the secretion of hematopoietic growth factors. The reduction of the number of tumor cells by cDDP leads to a decline of the number of phagocytic cells in accordance with the respective regression equations. In contrast to meso-1-PtCl2 and cDDP, ovariectomy causes elevated phagocyte numbers, probably due to the strongly reduced estrogen level. The studies described in this publication indicate that the anti-breast cancer activity of meso-1-PtCl2 is caused by a decimation of phagocytes and with this by an abolition of the tumor promoting effect. Furthermore, a restoration of the natural immunosurveillance seems to be of importance.

1-(2,6-dichloro-4-hydroxyphenyl)-2-phenylethanes--new biological response modifiers for the therapy of breast cancer. Synthesis and evaluation of estrogenic/antiestrogenic properties

[meso-1,2-Bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine]platinum(II) complexes (meso-1-PtLL'; L,L' = Cl or L = H2O and L' = OSO3) are highly effective towards hormone-sensitive, rodent breast cancers due to their significant estrogenic potencies. Their antitumor activities are caused by modification of the immune response. The pharmacophor of these compounds, the 1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethane (23H), was used as the lead structure in a structure-activity study with the goal of finding new biological response modifiers for the therapy of breast cancer. As intermediates for the synthesis of the 23H derivatives, the CH3O-substituted stilbenes 12E/12Z-16E/16Z were prepared by reaction of the related benzyltriphenylphosphonium halides with 2,6-dichloro-4-methoxybenzaldehyde by the method of Wittig/Campbell and Donald, respectively. Separation of the E/Z-mixtures was performed by fractional crystallization and/or column chromatography. The E-1,2-bis(2,6-dichloro-4-methoxyphenyl)ethene (17E) was obtained by reductive coupling of 2,6-dichloro-4-methoxybenzaldehyde with TiCl4/Zn according to the method of Mukaiyama. Illumination of the solution of 17E in benzene with UV light resulted in an E/Z-isomerization. Compound 17Z could be isolated from this mixture. The CH3O-substituted stilbenes were transformed into their 1,2-diphenylethanes (12H-17H) by catalytic hydrogenation of the C1=C2 double bond. Ether cleavage of the compounds was performed with BBr3. In the estrogen receptor binding assay all OH-substituted 1,2-diphenylethanes showed affinity to the estrogen receptor, which was about two orders of magnitude lower than that of 17 beta-estradiol. In the uterus weight test on the immature mouse 1,2-diphenylethanes with 4-substituted OH groups proved to be "true" estrogens (19H: 2-F/4-OH; 20H: 2-Cl/4-OH; 23H: 2,6-Cl2/4-OH), while those with a 3-substituted OH group in the 2-phenyl ring showed the properties of a "partial" estrogen (18H: 3-OH) or of an "impeded" estrogen (21H: 2-Cl/3-OH; 22H: 2-Cl/5-OH). The latter also showed significant additional antiestrogenic activity. The related E-stilbenes mostly exhibit similar hormonal activities. As a rule, the replacement of the OH groups by the CH3O groups and the change from the E- to the Z-configuration led to a reduction of the estrogenic potencies. Several of the 1-(2,6-dichloro-4-methoxyphenyl)-2-phenylethenes (12E: 3-OCH3; 12Z: 3-OCH3; 15E: 2-Cl/3-OCH3; 15Z: 2-Cl/3-OCH3; 16E: 2-Cl/5-OCH3) produced antiestrogenic effects in the uterus weight test. It is supposed that those new 1-(2,6-dichloro-4-hydroxyphenyl)-2-phenylethanes endowed with marked estrogenic properties are also active as biological response modifiers in animals bearing hormone-sensitive breast cancer. The antiestrogenic derivatives presumably inhibit the breast cancer development by competing with tumor growth stimulating endogenous estrogens for the binding to the receptor. This is to be confirmed in a further study.

Does [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine]- dichloro-platinum(II) act as an immune response modifier? Part III: Progressively growing MXT-M-3,2 breast cancer stimulates the proliferation of phagocytes in B6D2F1 mice

MXT-M-3,2 breast cancer implanted into female B6D2F1 mice accelerates the growth of an identical second tumor. This process is accompanied by a significant increase of the granulocyte and monocyte numbers in the blood and of the granulocyte and macrophage numbers in the spleen. A significant positive correlation of strong intensity was found between the tumor weight on the one hand and the number of the granulocytes and macrophages on the other hand. The tumor-dependent promotion of the myelopoiesis is explained with a secretion of hematopoietic growth factors, e.g. of the granulocyte-macrophage-stimulating growth factor (GM-CSF), by the breast cancer cells.