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]- 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

The anti-tumor activity of [meso-1,2-bis(2,6-dichloro-4- hydroxyphenyl)ethylenediamine]dichloroplatinum(II) on the MXT-M-3,2 breast cancer implanted into B6D2F1 mice was not significantly reduced by splenectomy or co-administration of cyclosporine A. Neither did the use of T-lymphocyte-deficient NMRI (nu/nu) mice as hosts substantially influence its anti-tumor effect. Obviously, [meso-1,2-bis(2,6-dichloro-4- hydroxyphenyl)ethylenediamine]dichloroplatinum(II) does not act by an enhancement of the specific immune defense.

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.

[Aqua-1-(2,6-dichloro-4-hydroxyphenyl)-2-phenylethylenediamine] sulfatoplatinum(II) complexes with variable substituents in the 2-phenyl ring. 3. Investigation of breast cancer inhibiting properties

In the search for new anti-breast cancer compounds a series of diastereomeric aqua[1-(2,6-dichloro-4-hydroxyphenyl)-2-phenylethylenediamine]sulfato platinum(II) complexes was tested on the hormone-sensitive MXT-M-3.2 breast cancer of the mouse. By simultaneous determination of tumor and uterine weights at the end of the experiment we obtained an insight into the mode of action. Changes in the uterine weights indicate whether the anti-breast cancer effect of the test substance is caused either by its capability to reduce the endogenous estrogen level via inhibition of estrogen biosynthesis (mechanism B), or by its estrogenic side effects which enhance the immune defense in the host animals (mechanism C). Studies on the [3H]thymidine incorporation into DNA of MDAMB-231 breast cancer cells showed that all test compounds inhibit deoxyribonucleic acid synthesis, like cisplatin (mechanism A). However, in comparison to the standard cisplatin, their activities were low. The three most effective test compounds threo-2-PtSO4 (2-phenyl-residue), threo-5-PtSO4 (2-(4-hydroxyphenyl)-residue), and threo-8-PtSO4 (2-(2-fluoro-4-hydroxyphenyl)-residue) seem to exert their anti-breast cancer effect by mechanism B. Moreover, threo-5-PtSO4 was moderately active on the hormone- insensitive MXT-M-3.2 (Ovex) breast cancer of the mouse. Aqua[erythro-1-(2,6-dichloro-4-hydroxyphenyl)-2-(2-chloro-4-hydroxypheny l) ethylenediamine]sulfato-platinum(II) (erythro-9-PtSO4) was the only breast cancer inhibiting compound of the series acting mainly according to mechanism C. A minor contribution of mechanism A, impairment of the DNA function in the tumor cell, to the anti-breast cancer activity of these aqua[1-(2,6-dichloro-4-hydroxyphenyl)-2-phenylethylenediamine]sulfato platinum(II) complexes cannot be excluded, since such effects are apparent in the MDA-MB-231 as well as in the MCF-7 breast cancer cell line at higher drug concentrations. In this test series which was performed with the crystal violet chemosensitivity assay, the MCF-7 cells proved to be somewhat more sensitive.

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 1: The MXT-M-3.2 breast cancer stimulates the growth of an identical second graft; [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine]dichloroplat inum (II) inhibits this process

The MXT-M-3.2 breast cancer implanted into female B6D2F1 mice accelerates the growth of an identical second tumor. This process is inhibited by [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl) ethylenediamine]dichloroplatinum(II). The possible modes of action of this compound as a biological response modifier are discussed.

[meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine] sulfatoplatinum(II)--pharmacokinetic studies

The maximally attainable level of the non-plasma protein bound fraction of a single 10.0 mumol/kg i.p. dose of [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine] sulfatoplatinum(II), a drug active on the murine, hormone-sensitive MXT-M-3.2 breast cancer, lies markedly below the concentration causing a significant cytotoxic effect on a cell line derived from this tumor. This result confirms our opinion that the strong in vivo activity of this drug on hormone-sensitive breast cancers is mediated by its estrogenic potency by analogy with high dosed steroidal and non-steroidal estrogens. A specific cytotoxic effect utilizing the estrogen receptor as carrier, as formerly postulated, is unlikely.

[meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl) ethylenediamine]dichloroplatinum(II), a compound with a specific activity on hormone-sensitive breast cancers--evidence for a diethylstilbestrol-like mode of action

[meso-1,2-Bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine]- dichloroplatinum(II) (meso-1-PtCl2), an estrogenic and cytotoxic platinum complex, shows activity against ER+ but not against ER- breast cancers in vivo (ER: estrogen receptor; ER+ and ER- indicate the presence or absence of the ER). To clarify whether its estrogenic or its cytotoxic potency or both properties are the cause of this specific inhibitory effect, we tested meso-1-PtCl2 comparatively in vivo on an ER+ and an ER- murine breast cancer (MXT-M-3.2 MC and MXT-M-3.2(ovex) MC, respectively), and in vitro on two cell lines derived from the former in vivo models (MXT+ and MXT-, respectively). The estrogens diethylstilbestrol (DES) and the ligand of meso-1-PtCl2 (meso-1), responsible for the hormonal effect of meso-1-PtCl2, and the cytotoxic drug cisplatin (cDDP) were used as comparative substances. Meso-1-PtCl2. DES and cDDP showed a strong and comparable activity on the ER+ MXT-M-3.2 MC in vivo, meso-1 being somewhat less inhibitory. In experiments on the murine, ER- MXT-M-3.2(ovex) MC only cDDP caused a marked inhibitory effect. The other compounds were inactive or only marginally active. In accordance with the in vivo results cDDP was also very active on the MXT+ and MXT- breast cancer cell line. In contrast to this meso-1-PtCl2, meso-1, and DES proved to be only weakly active or inactive on both cell lines. From these results it can be concluded that there is only little if any contribution of the cytotoxic PtCl2 moiety of meso-1-PtCl2 to the anti-breast cancer activity in vivo. On the ER+ MXT-M-3.2 MC transplanted into ovariectomized mice meso-1-PtCl2 yielded a biphasic dose activity curve, i.e. an increase of the tumor growth at low doses followed by a decrease at high doses, identical with those of the estrogens DES and meso-1. These results indicate that meso-1-PtCl2 inhibits ER+ breast cancers by its estrogenicity in the same manner as meso-1 and DES. The complex mechanism of anti-breast cancer active estrogens involves presumably the endocrine and/or the immune system. Its investigation is the subject of further studies.

Stability and cellular studies of [rac-1,2-bis(4-fluorophenyl)-ethylenediamine][cyclobutane-1,1- dicarboxylato]platinum(II), a novel, highly active carboplatin derivative

The synthesis of the diastereomeric [1,2-bis(4-fluorophenyl)ethylenediamine][cyclobutane-1, 1-dicarboxylato]platinum(II) complexes, rac- and meso-4F-Pt(CBDC), the evaluation of their structures, their tumor-inhibiting properties and their stability in physiological environment are described (reference complexes: the dichloro- and sulfatoplatinum(II) analogues, carboplatin and cisplatin). The most interesting diastereomer, rac-4F-Pt(CBDC), equals cisplatin and surpasses carboplatin in its effect on human breast cancer cell lines (MCF-7 and MDA-MB-231). Rac-4F-Pt(CBDC) is largely insensitive against attack of nucleophiles e.g. Cl-, a prerequisite for sufficient stability in vivo and for fewer side effects. In accordance with this, in vitro studies on the binding of rac-4F-Pt(CBDC) to albumin, the main plasma protein, show that the free, non-protein-bound fraction is relatively high, coming close to that of carboplatin. These properties are of importance for the transferability of the promising effects found in the cell culture experiments to in vivo conditions. The distinctly better anti-breast cancer activity of rac-4F-Pt(CBDC) than of carboplatin has been attributed to its ability to accumulate in the tumor cells. The human ovarian cancer cell line NIH-OVCAR-3 is also strongly inhibited by rac-4F-Pt(CBDC).

Synthesis and antitumor activity of [1,2-bis(4-fluorophenyl)ethylenediamine][dicarboxylato]platinum(II) complexes

The synthesis of the diastereomeric [1,2-bis(4-fluorophenyl)-ethylenediamine][dicarboxylato]platinum(I I) complexes, rac- and meso-4F-Pt(X) [X: oxalato (Ox), malonato (Mal), hydroxymalonato (OHMal), phenylmalonato (PhMal), tetrahydro-4H-pyran-4,4-dicarboxylato (Thpdc)], the evaluation of their structure, water solubility, resistance against attack by nucleophiles, and growth inhibiting properties on the human MCF-7 breast cancer cell line are described [parent compounds: rac-4F-Pt(CBDC) and meso-4F-Pt(CBDC); reference complexes: carboplatin, cisplatin, rac- and meso-4F-PtCl2]. The most active 4F-Pt(X) complexes, rac-4F-Pt(Mal), rac-4F-Pt(OHMal) and rac-4F-Pt(Thpdc), equal the parent compound rac-4F-Pt(CBDC) as well as cisplatin and surpass carboplatin in their effect on the MCF-7 breast cancer cell line. Their water solubility, which is of importance for an application in the cancer chemotherapy, is higher than that of rac-4F-Pt(CBDC), especially in the case of rac-4F-Pt(OHMal) and rac-4F-Pt(Thpdc). In comparison to the dichloroplatinum(II) analogue (4F-PtCl2) the stability of the three compounds in the presence of the strong nucleophile iodide is markedly enhanced, which means a reduction of the protein bound drug fraction in the blood and tissue compartments accompanied by an increase of the active, free drug level. The found physiochemical properties of these compounds meet the requirements for the transferability of their promising breast cancer inhibiting effects detected in cell culture experiments to in vivo conditions.

Discrepancy between cytotoxicity, platinum accumulation, and DNA platination in MCF-7 breast cancer cells treated with diaqua (1,2-diphenylethylenediamine) platinum (II) sulfates and cisplatin

Cisplatin (cis), raceme-diaqua[1,2-bis(4-fluorophenyl)ethylenediamine] platinum(II) sulfate (r-4F-PtSO4), meso-diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]platinum(II) sulfate (m-4F-PtSO4), and meso-diaqua[1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine] platinum(II) sulfate (m-2,6Cl2-4OH-PtSO4) were compared with regard to their growth inhibitory effect on MCF-7 breast cancer cells. At concentrations of 5 microM, cis, r-4F-PtSO4, and m-4F-PtSO4 were essentially equiactive, whereas m-2,6Cl2-4OH-PtSO4 was ineffective. Platinum measurements by neutron activation analysis showed that a 24-h treatment of the MCF-7 cells with r-4F-PtSO4 and m-4F-PtSO4 caused a 22.3- and 10.3-fold accumulation, respectively, whereas the accumulation factors for cis (2.55) and m-2,6Cl2-4OH-PtSO4 (1.83) were very low. The comparison of DNA-associated platinum revealed a similar tendency. After 24 h of drug exposure, the base pair/ platinum ratios were: 2.1.10(4) for r-4F-PtSO4, 3.7.10(4) for m-4F-PtSO4, 6.1.10(4) for cisplatin, and 8.1. 10(4) for m-2,6Cl2-4OH-PtSO4. Thus, the grade of cytotoxicity was correlated neither with the extent of cellular platinum enrichment nor with the degree of genomic DNA platination.

Development of a parenterally administrable hydrosol preparation of the "third generation platinum complex" [(+/-)-1,2-bis(4-fluorophenyl)ethylenediamine]dichloroplatinum(II). Part 1. Preparation and studies on the stability and antitumor activity

The development of a galenical formulation for poorly water soluble dichloroplatinum(II) complexes suitable for the parenteral administration in cancer chemotherapy is described. The procedure, which we elaborated for [(+/-)-1,2-bis(4-fluorophenyl)ethylenediamine]dichloroplatinum(II) (rac-4F-PtCl2), is based on the reaction of a soluble diaquaplatinum(II) salt with sodium chloride in water in the presence of pluronic F 68 as stabilizer and results in a sufficiently stable colloidal solution (i.e. hydrosol). In contrast to the poorly water soluble synthetic rac-4F-PtCl2, which was ineffective towards the hormone sensitive MXT-M-3.2 breast cancer of the mouse, its hydrosol formulation proved to be highly active and was very well tolerated.

Third generation antitumor platinum(II) complexes of the [1-(fluoro/difluorophenyl)-2-phenylethylenediamine]platinum(II) type

The diastereomeric 1-(fluoro/difluorophenyl)-2-phenylethylene-diamines (4-fluoro: erythro-1/threo-1; 2,4-difluoro: erythro-2/-threo-2; 2,6-difluoro: erythro-3/threo-3) and the diastereomeric 1-(4-fluorophenyl)-2-(3-hydroxyphenyl)ethylenediamines (erythro-4/-threo-4) were synthesized from appropriately substituted stilbenes by reaction with IN3 and subsequent LiAlH4 reduction. Coordination of the 1,2-diphenylethylenediamines to platinum was carried out by use of K2PtI4. The water-soluble aquasulfato-platinum(II) complexes (erythro/threo-1-PtSO4-erythro/threo-4-PtSO4) were obtained from the diiodoplatinum(II) complexes by reaction with Ag2SO4. Additionally erythro/threo-1-PtSO4 and erythro/threo-4-PtSO4 were transformed into the dichloroplatinum(II) complexes (erythro/threo-1-PtCl2, erythro/threo-4-PtCl2) by treatment with KCl. In contrast to the less effective erythro-configurated sulfatoplatinum(II) complexes the threo-analogues showed comparable or even superior activities to cisplatin on the human MDA-MB-231 breast cancer cell line. On the MXT-M-3.2 breast cancer of the mouse only erythro- and threo-4-PtSO4 caused similar effects like cisplatin. The strong inhibitory effect of the diastereomeric sulfatoplatinum(II) complexes on the P-388 leukemia of the mouse was equal to that of cisplatin. On the latter tumor threo-4-PtCl2 was the most active among the less toxic dichloroplatinum(II) derivatives.

Investigation of the configurational and conformational influences on the hormonal activity of 1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamines and of their platinum(II) complexes. 1. Synthesis, estradiol receptor affinity, and estrogenic activity of diastereomeric [N-alkyl- and N,N'-dialkyl-1,2- bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine]dichloroplatinum(II) complexes

N-Monoalkylated (Et) and N,N'-dialkylated (Me and Et) 1,2-bis(2,6-dichloro-4-hydroxyphenyl)-ethylenediamines and their dichloroplatinum(II) complexes were synthesized, and their configuration and conformational behavior were 1H-NMR spectroscopically clarified. The latter was brought in relation to their relative binding affinity (RBA) to the estrogen receptor as well as to their estrogenic potency. In contrast to the RR/SS-configurated diamines, the R/S-configurated ones showed marked estrogenic properties which correlate with the RBA's. In the related R/S-configurated complexes the estrogenic activity is determined by the same structural requirements as in the diamine series. However, a correlation between RBA's and estrogenic potencies is missing. The connection between spatial structure and activity is discussed by use of a drug-receptor model recently proposed by Höltje and Dall.

Reduction of the estrogenic side effects of the mammary tumor-inhibiting drug [1,2-bis(2,6-dichloro-4-hydroxyphenyl)- ethylenediamine]dichloroplatinum(II) by variation of ring substituents

[1,2-Bis(4-methoxy/4-hydroxyphenyl)ethylenediamine]dichloroplatinum-(II) complexes with Cl-, CH3-, or OCH3-substituents in the ortho-positions of the aromatic rings (meso-1-PtCl2, D,L-1-PtCl2, meso-2-PtCl2, D,L-2-PtCl2, meso-3-PtCl2, meso-4-PtCl2, meso-5-PtCl2) were tested on the MDA-MB 231 breast cancer cell line, the lymphocytic leukemia P388, and the estrogen receptor-positive and -negative MXT mammary carcinoma of the mouse (MXT,ER(+)-MC, MXT,ER(-)-MC). The comparison of the effects of methoxy-substituted complexes (meso-1-PtCl2, D,L-1-PtCl2, meso-3-PtCl2) with those of the respective hydroxy-substituted ones (meso-2-PtCl2, D,L-2-PtCl2, meso-4-PtCl2) shows that a reduction of estrogenic effects as well as a total loss of the mammary tumor-inhibiting activity takes place on methylation of the 4-OH group. The exchange of the 2,6-standing chlorine atoms by methyl groups in meso-2-PtCl2 led to the non-estrogenic, but on the MXT,ER(+)-MC highly effective derivative meso-4-PtCl2 which proved to be also cytotoxic on ER(-)-tumors such as MXT,ER(-)-MC, and the P388 leukemia.

Hyaluronidase significantly enhances the efficacy of regional vinblastine chemotherapy of malignant melanoma

The regional chemotherapy of the human malignant melanomas (SK-MEL-2, -3, -5, -24) implanted in NMRI nu/nu mice with a combination of the hyaluronic-acid-cleaving enzyme hyaluronidase (HYase) and vinblastine is a very effective therapeutic procedure. In three out of four melanoma models (SK-MEL-2, -3, -5) the weekly peritumoral administration of high-dose HYase (100,000 IU/kg) 4 h prior to the injection of 0.3 mg/kg vinblastine in the vicinity of the tumor (seven weekly therapeutic cycles) caused marked antitumor effects, while HYase and vinblastine were inactive when given alone. The pretreatment with HYase, which is well tolerated by the test animals, prevented local inflammation reactions commonly seen after subcutaneous vinblastine administration. Tumor growth and metastatic behavior of the melanomas used were neither increased nor reduced by HYase after peritumoral administration without subsequent vinblastine injection. The curative activity of the regional chemotherapy with HYase/vinblastine could be demonstrated on the SK-Mel-3 melanoma. After an observation time of 18 weeks, tumor cells could no longer be detected in the subcutaneous region of the former lesion. Only macrophages, which had abundantly incorporated melanin, gave evidence of previously growing tumors. In contrast to the controls, no metastases could be observed in the axillary lymph nodes of the test animals.

Investigation of the conformational influences on the estrogenic activity of 1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamines and of their platinum(II) complexes, II: Synthesis and studies on the estrogenic activity of cis- and trans[bis(2,6-dichloro-4-hydroxybenzylamine)]dihaloplatinum(II)-c omplexes

2,6-Dichloro-4-hydroxybenzylamine (1) and its N-methyl (2) and N-ethyl (3) derivatives were synthesized and tested for estrogen receptor affinity as well as for estrogenic activity. In contrast to their related highly active 1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamines (meso-4 - meso-6) none of the benzylamines showed hormonal activity. The coordination of the benzylamine 1 to platinum did not lead to an estrogenic compound. The reasons for the different activity of [meso- 1,2(bis-2,6-dichloro-4-hydroxyphenyl)ethylenediamine]dichloroplatinum(II ) (meso-4-PtCl2) and cis[bis(2,6-dichloro-4-hydroxybenzylamine)]dichloroplatinum(II) (cis-1-PtCl2), the latter of which can be considered as a ring-opened counterpart of the highly active meso-4-PtCl2, are thoroughly discussed under inclusion of conformational facts. The results of this and the preceding work show, that the pharmacophore meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine (meso-4) which is exclusively responsible for the estrogenic activity of meso-4-PtCl2 causes comparable hormonal effects in two different conformations with O-O distances of about 8 A (complex) and of about 12 A (diamine). Therefore, we discuss two binding sites for estrogens in their receptor.

A rapid luciferase transfection assay for transcription activation effects and stability control of estrogenic drugs in cell cultures

A rapid assay system for measuring the potential of estrogenic drugs is introduced. Luciferase induction could be measured in estrogen-receptor-positive human MCF-7 breast cancer cells, which had been transfected with a novel luciferase reporter plasmid ERE luc. The minimal requirement was 1 h exposure to the inducing drug and 3.5 h of incubation after removal of the drug. The assay system was used to measure the stability of the drug diaqua-[1,2-bis (2,6-dichloro-4-hydroxyphenyl) ethylenediamine] platinum(II) sulfate, containing an estrogenic ligand and reactive platinum. Luciferase activity was observed only when the drug was in the culture medium and cells for short times, whereas the estrogenic ligand alone remained active. It is assumed that binding of the platinum moiety to macromolecular constituents of the culture or cells renders the drug inaccessible for binding to the estrogen receptor.

Aqua[1-(2,6-dichloro-4-hydroxyphenyl)-2- phenylethylenediamine]sulfatoplatinum(II) complexes with variable substituents in the 2-phenyl ring, II: Correlation of molecular structure and estrogenic activity of breast and prostate cancer inhibiting. [erythro-1-(2,6-dichloro-4-hydroxyphenyl)-2-(2-halo-4- hydroxyphenyl)ethylenediamine]platinum(II) complexes

Complete three-dimensional X-ray crystal structure analyses of estrogenic [erythro-1-(2,6-dichloro-4-hydroxyphenyl)-2-(2-halo-4- hydroxyphenyl)ethylenediamine]diiodoplatinum(II) complexes (halo = fluoro:erythro-8PtI2 and halo = chloro:erythro-9-PtI2) which were synthesized for application in breast and prostate cancer, have been carried out. 6239 as well as 6521 reflexes were measured and refined to an R-value of 0.105 and 0.066, respectively. The molecules of erythro-8-PtI2 are displaced laterally from a possible Pt-Pt-axis separated, alternatingly, by Pt-Pt-distances of 3.62 A and 6.27 A. A comparable structure possesses erythro-9-PtI2 with Pt-Pt-distances of 3.59 A and 6.32 A. The ethylenediamine ligands of erythro-8-PtI2 and erythro-9-PtI2 are puckered and exist in half chair conformations. For both complexes the 2,6-dichloro-4-hydroxyphenyl ring is equatorially arranged, while the 2-halo-4-hydroxyphenyl ring is nearly perpendicular to the N-Pt-N plane. The O-O-distance between the phenolic oxygens amounts to 8.1 A in erythro-8-PtI2 and to 7.8 A in erythro-9-PtI2. Though these O-O-distances differ strongly from that (12.1 A), which is considered to be necessary for the binding of an estrogen to its receptor, [1-(2,6-dichloro-4-hydroxyphenyl)- 2-(2-halo-4-hydroxyphenyl)ethylenediamine)]platinum(II) complexes show estrogenic effects which are, however, strongly reduced compared to that of therapeutically used estrogens like diethylstilbestrol. The relationship between molecular structure and estrogenicity as well as the significance of the latter for antitumor activity and untoward side effects are thoroughly discussed.

[meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine]- dichloroplatinum(II), a new drug not only parenterally but also orally active in the therapy of breast and prostate cancer

The platinum complex [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)- ethylenediamine]dichloroplatinum(II),K, was tested for its antitumor activity on hormone-sensitive tumor models under peroral administration. The resorption from the gastrointestinal tract was proved by determining the estrogenic effect of K in a dose/activity study using the immature-mouse uterine weight test. In comparison to the subcutaneous injection, a tenfold peroral dose was administered to achieve identical effects. By peroral treatment of the hormone-sensitive MXT(M3.2) mammary carcinoma of the mouse with K an almost complete inhibition of the tumor growth was obtained. This effect was superior to that of subcutaneously applied cisplatin and significantly better than that obtained by perorally administered ligand L at an equimolar dose, indicating that the antitumor effect is caused by the intact complex K and not by the liberated ligand L. The strong antitumor activity of perorally applied K was also demonstrated on the hormone-sensitive Noble Nb-R prostatic carcinoma of the rat. Histological examinations showed that the platinum complex K did not cause cisplatin-like kidney damage or irritations of gastric or intestinal mucosa when given perorally.

Computer modelling of estrogenic transcriptional activation can account for different types of dose-response curves of estrogens

Estrogenic activity of diphenylethanes and -ethenes was determined by uterine growth in immature mice and analyzed by weighed regression of logit-transformed effect on log dose values. This resulted in a range of Hill coefficients nH from 0.3 to 2 corresponding to the molecular mechanism of estrogenic transcriptional activation. Binding of agonists (hormones, H) to estrogen receptors (ER) leads to receptor dimerization depending on the structure of the ligand. Three hormone-receptor complexes, H-ER, H-ER-ER, and H-ER-ER-H, which bind with different affinity to short palindromic DNA sequences (estrogen responsive elements), can be proposed. Transcriptional activating functions of the DNA-bound ER are subsequently induced. We have derived an equilibrium model including these steps. Computer simulations of Hill plots based on the model have completely reproduced the range of observed nH values. Hill coefficients are > 1.5 if the homodimer H-ER-ER-H and < 0.7 if the heterodimer H-ER-ER strongly predominates. If ER dimerization is disturbed (H-ER monomer predominant), nH is closer to 1. Hill coefficients and pD2 values (negative decadic logarithms of molar estrogen doses causing 50% of the maximal effects) are related to parameters of ER dimerization and the two steps of hormone-receptor dissociation. When a series of 1,2-bis(3'-or 4'-hydroxyphenyl)ethanes and -ethenes is studied, a rather simple dependence of nH and pD2 on the nature of alkyl groups symmetrically substituted at C-atoms 1 and 2 can be observed. In terms of the model this implies that ethyl and alpha-branched higher alkyl substituents (nH >> 1) appear to stabilize the homodimer, while methyl and CF3 groups (nH << 1) could lead to a rapid dissociation of the homodimer to the heterodimer. With longer n-alkyl and beta-branched alkyl substitution (nH from 0.66 to 1.3), dimerization itself can be limited or the ligand-homodimer dissociation is only moderately increased. Thus, a strong sterical constraint could exist with respect to the stabilization of the second ligand-receptor bond in the homodimer.

Mammary tumor inhibiting [1,2-bis(2,6-dihalo-3-hydroxyphenyl)ethylenediamine]platinum(II) complexes, III: Relationship between structure and estrogenic activity of the diamine ligands, their sulfatoplatinum(II) and diiodoplatinum(II) complexes

1,2-Bis(2,6-dihalo-3-hydroxyphenyl)ethylenediamines with 2,6-Cl2, 2-F-6-Cl, 2-Cl,6-F, and 2,6-F2 substituents (meso-1 to meso-4, D,L-1 and D,L-4) and their sulfatoplatinum(II) complexes were tested in the immature mouse uterine weight test. The only complex with marked estrogenic properties proved to be meso-1-PtSO4. Surprisingly its diamine ligand meso-1 was only marginally active. 1H-NMR spectroscopic studies on the 1,2-diphenylethylenediamine ligand reveal that the 2,6-standing Cl-atoms in meso-1 (antiperiplanar phenyl residues) hinder the rotation of the aromatic rings, which results in very stable conformers with different O-O distances owing to the unsymmetric arrangement of the ring substituents. On transformation into the Pt(II) complex the conformations of meso-1 change (synclinal phenyl residues) and a delta and lambda interconversion takes place already at physiological temp. (37 degrees C). This process is accompanied by a rotation of phenyl rings, which is supposed to allow an optimal fit for the formation of hydrogen bridges to the estrogen receptor, resulting in a marked estrogenic activity. The other ligands and complexes are inactive presumably due to a diminished hydrophobic interaction with the estrogen receptor, resulting from their R,R/S,S-configuration or the reduced number of Cl-atoms.

Antitumour activity of miltefosine alone and after combination with platinum complexes on MXT mouse mammary carcinoma models

Miltefosine, an alkylphosphocholine structurally related to alkyllysophospholipids showed highly selective antitumour activity against the hormone-sensitive variant of the s.c. transplantable MXT mouse mammary adenocarcinoma, the ovary-dependent MXT (M3.2), whereas it was inactive against the hormone-insensitive MXT (M3.2) OVEX variant. A dose of 32 mg/kg miltefosine p.o. daily for 5 weeks was well tolerated. Histopathological evaluation gave no signs of gastroenteral toxicity. After therapy the microarchitecture of the MXT (M3.2) tumours changed from that of a moderately differentiated adenocarcinoma to that of an anaplastic mammary carcinoma. A dose of 16 mg/kg miltefosine p.o. daily, though in effective per se, enhanced the antitumour activity of suboptimal i.p. doses of cisplatin and the hormone-like platinum analogue meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl) ethylenediamine]dichloroplatinum(II). Furthermore, it was shown, that miltefosine exhibited no (anti)hormonal properties. However, the mechanism of action of miltefosine remains unclear.

Diamine ligand release from the cisplatin analogue [meso-1,2-bis(2,6-dichloro-4- hydroxyphenyl)ethylenediamine]dichloroplatinum(II) in cell culture medium

The stability of the five-membered chelate ring of the cisplatin analogue [meso-1,2-bis(2,6-dichloro-4- hydroxyphenyl)ethylenediamine]dichloroplatinum(II) was investigated under typical cell culture conditions (IMEM-Richter's medium with 10% fetal calf serum, 37 degrees C). For this purpose, the platinum compound was radiolabeled with tritium in the meta position of the aromatic ring by an acid-catalyzed tritium-exchange reaction, and a reversed-phase HPLC assay with radiochemical detection was developed to monitor for the presence of the free diamine ligand in the cell culture medium. A gradual increase in radioactivity attributed to the free diamine was found in medium containing the dichloroplatinum(II) complex (ca. 25% after 24 h), indicating that the diamine ligand was being released from the metal atom. When 1 mM glutathione (GSH) was included in the incubation medium, the amount of free diamine nearly doubled after 24 h, while the amount of radioactivity attributed to serum protein-platinum adducts decreased relative to incubations without GSH. On the other hand, the omission of serum from the incubations resulted in a dramatic decrease in the amount of radioactivity eluting under the diamine peak, while the concentrations of the two methionine-Pt adducts, which formed in a 1:1 ratio, rose. Through the use of liquid secondary ion mass spectroscopy, the two methionine-Pt adducts were identified as monomethionine metabolites of the title compound, whereby the two chloride ligands have been replaced by the amino acid. These compounds are probably diastereomers since the sulfur of methionine can coordinate to platinum with equal probability either cis or trans to the R-configured benzylamine carbon. On the basis of the chemical shifts of the MeS groups in the 250-MHz 1H NMR, it is concluded that a S,N-five-membered chelate ring is present in these methionine-Pt adducts.

[1,2-Bis(2-hydroxyphenyl)ethylenediamine]dichloroplatinum(II), a new compound for the therapy of ovarian cancer. II. Synthesis and preliminary testing of the enantiomeric complexes

The enantiomeric [1,2-bis(2-hydroxyphenyl)-ethylenediamine]dichloroplatinum(II) complexes were synthesized and their configuration assessed. A preliminary test in the cisplatin-resistant human NIH:OVCAR-3 ovarian cancer cell line, which was previously characterized by its sensitivity against several therapeutically used drugs, showed that both enantiomers produce cytocidal effects in a concentration of 2.5 microM. A difference between the enantiomers became evident from the faster onset of cytocidal activity of the S,S-configurated compound.

[1,2-Bis(2-hydroxyphenyl)ethylenediamine]dichloroplatinum(II), a new compound for the therapy of ovarian cancer. III. Detailed evaluation of the antitumor activity of the enantiomeric complexes on the human NIH:OVCAR-3 ovarian cancer cell line

The stereoisomeric [1,2-bis(2-hydroxyphenyl)ethylenediamine]dichloroplatinum(II) complexes were thoroughly tested on the cisplatin-resistant human NIH:OVCAR-3 ovarian cancer cell line. The racemate and its enantiomers produced cytocidal effects at a concentration of 2.5 microM (incubation time 256 h). The meso form, however, was merely cytostatically active. Differences between the enantiomers became evident after a short drug incubation time (1 h) followed by an incubation in drug-free medium (243 h). The S,S-configurated enantiomer (-)-3-PtCl2 proved to be the most active compound. To achieve cytocidal effects concentrations of 2.5-5.0 microM and incubation times of about 3 h were necessary for (-)-3-PtCl2. This compound is also sufficiently stable under test conditions as shown by the preincubation in cell-free medium for 3 h. These results and the augmentation of its antitumor activity by buthionine sulfoximine recommend the further preclinical development of (-)-3-PtCl2 for clinical use.

Stereoisomeric [1,2-bis(3-hydroxyphenyl)ethylenediamine]platinum(II) complexes, Part III: Evaluation of the mammary tumor inhibiting properties

Stereoisomeric [1,2-bis(3-hydroxyphenyl)ethylenediamine]platinum(II) complexes produce a strong configuration-dependent inhibition of the hormone sensitive MXT-mammary carcinoma of the mouse. Besides an interference in the DNA synthesis in analogy to cisplatin an estrogen level lowering effect is supposed to be the mode of action. The new complexes show also a significant activity on the hormone-independent MXT-mammary carcinoma of the mouse.

Dichloro-[1-(hydroxyphenyl)-2-phenylethylenediamine]platinum(II) complexes: testing on the human ovarian cancer cell lines NIH: OVCAR3 and SK OV 3

The diastereoisomeric dichloro-[1-(2-, 3- and 4-hydroxyphenyl)-2-phenylethylenediamine]platinum(II) complexes were tested on two human ovarian cancer cell lines NIH: OVCAR-3 and SK-OV-3, both resistant against cisplatin. Dichloro-[threo-1-(3-hydroxyphenyl)-2-phenylethylenediamine]platinum(II) (threo-5-PtCl2) proved to be the most active representative of the new series, producing cytocidal effects at a concentration range of 2.5 to 5.0 microM on the NIH: OVCAR-3 cell line. On the more resistant SK-OV-3 cell line, threo-5-PtCl2 was only moderately active, while in combination with BSO, a GSH level lowering compound, threo-5-PtCl2 showed a strong synergistic effect.

Standardized kinetic microassay to quantify differential chemosensitivity on the basis of proliferative activity

Conventionally in vitro cytotoxicity assays are performed as single-end-point determinations. To compensate for the diversity of growth rates among different cell lines in this report we describe a computerized kinetic chemosensitivity assay based on quantification of biomass by staining cells with crystal violet. As a prerequisite four human breast cancer cell lines (MDA-MB-231, MCF-7, T-47-D and ZR-75-1) were characterized with regard to oestrogen and progesterone receptor content, modal chromosome number and proliferation kinetics depending on the number of passages in culture. With prolonged time in culture for ZR-75-1 exposed to various concentrations of cisplatinum a dose-related increase in drug effect was observed. Owing to a correction of the T/C values for the initial cell mass (at the time when drug is added) a sharp distinction between cytostatic and cytocidal drug effects becomes obvious in plots of corrected T/C values versus time of incubation. The influence of the untreated control on the corrected T/C values and possible time courses of theoretical inhibition profiles (reflecting cytostatic, transient cytotoxic or cytocidal drug effects as well as development of resistance) and their relationship to the corresponding growth curves of drug-treated cells are discussed. Chemosensitivity assays with diethylstilbestrol dipropionate, tamoxifen, melphalan, cisplatinum, vinblastine, Adriamycin and 5-fluorouracil prove the theoretical considerations to be true for MDA-MB-231, MCF-7, T-47-D and ZR-75-1 human breast cancer cell lines in practice.

Chemosensitivity of human MCF-7 breast cancer cells to diastereoisomeric diaqua(1,2-diphenylethylenediamine) platinum(II) sulfates and specific platinum accumulation

Cisplatin, raceme-diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]platinu m(II) sulfate (compound I), meso-diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]-platinum(II) sulfate (compound II), and meso-diaqua[1,2-bis(2,6-dichloro-4- hydroxyphenyl)ethylenediamine]platinum(II) sulfate (compound III) were compared with regard to their effect on the MCF-7 breast cancer cell line in vitro. At equimolar concentrations (5 microM), cisplatin, compound I, and compound II were equiactive after 231 h drug exposure, whereas compound III was ineffective. Although compounds I and II showed markedly greater inactivation than did cisplatin after 6 h incubation with culture medium, compound I (but not compound II) exhibited antitumor activity equivalent to that of cisplatin when cells were exposed to the drugs for 6 h. Platinum measurements by neutron-activation analysis revealed that compound I was selectively and rapidly accumulated by MCF-7 cells, resulting in a high degree of DNA platination within the first few hours of drug exposure. However, when the drug-exposure period was long enough, platinum enrichment was not reflected in an overall difference in the cytotoxicity of compound I vs cisplatin. Nevertheless, compound I should be superior to cisplatin in vivo, provided that effective plasma levels can be maintained for about 6 h.

Different response of murine and human mammary tumour models to a series of diastereoisomeric [1,2-bis(difluorophenyl) ethylenediamine]dichloroplatinum(II) complexes

A series of isomeric [1,2-bis(difluorophenyl) ethylenediamine]dichloroplatinum(II) complexes and cisplatin were tested on the P388 leukemia and on the murine hormone-independent MXT (M3.2) OVEX and the ovarian-hormone-dependent MXT (M3.2) mammary carcinoma for evaluating antineoplastic activity against breast cancer in vivo. Although these results were heterogeneous, a trend to the 2,6-difluorosubstituted compound as the most active platinum complex was observed. For the development of a large-scale in vitro screening method on human breast cancer cell lines, cell number, [3H]thymidine incorporation, and crystal violet staining were evaluated as parameters for end-point determination. Chemosensitivity testing on the human breast cancer cell lines MDA-MB-231 and MCF-7 unambiguously identified [1,2-bis(2,4-difluorophenyl)ethylenediamine]dichloroplatinum(II) as the complex with the highest activity in the crystal violet micro-assay. In equimolar concentration this compound was superior to cisplatin on both cell lines. The analysis of the conflicting results of this study indicates that murine mammary carcinomas are most probably unrealistic and inappropriate models for the screening of cytotoxic platinum complexes with potential activity on human breast cancer.

Dissociation of estrogenic and cytotoxic properties of an estrogen receptor-binding platinum complex in human breast cancer cell lines

The Pt complex [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)-ethylenediamine]diaqua -Pt(II) sulfate (meso-6-PtSO4) was designed with the concept of combining the cytotoxic cisplatin with an estrogen receptor (ER)-binding ligand for targeting to ER+ mammary tumor cells. This Pt complex selectively inhibits growth of ER+ mammary tumors in rodents. To study the cellular mechanisms of action, cultures of two human mammary tumor cell lines, MCF-7 (ER+) and MDA-MB231 (ER-), were used and the effects of estradiol, tamoxifen, and cis-Pt compared with those of meso-6-PtSO4. The relative binding affinity of the meso-6-PtSO4 to the ER in MCF-7 cells was 0.35 compared to estradiol (relative binding affinity, 100). Nevertheless, the Pt complex was able to induce ER processing and increase the level of the progesterone receptor at concentrations of 1-10 nM. Growth of MCF-7 cells was inhibited at concentrations of meso-6-PtSO4 greater than 10 microM. MDA-MB231 cells were inhibited likewise by the Pt complex, indicating a lack of selectivity for the ER+ cells. The results show that meso-6-PtSO4 possesses both estrogen-like and cis-Pt-like properties. Since growth inhibition did not correlate with ER-mediated processes, these two properties are expressed independently at the cellular level. The selective growth inhibitory effect of meso-6-PtSO4 in vivo is suggested to involve endocrinological and/or immunological factors.

[Potential antiestrogens of the 1,2-diphenyl-1-pyridyl-but-1-ene type. 2. Biological testing]

Z-1-(4-hydroxyphenyl)-1-(4-resp. 3-pyridyl)-2-phenyl-but-1-enes Z-1 and Z-2 and their acetates Z-1a and Z-2a are weak estrogens (uterine weight test, immature mouse), which cause a marked tumor growth inhibition on the hormone-dependent MXT mammary carcinoma of the mouse. No or just slight estrogenic side effects determined by uterine weight are detectable in this tumor experiment.

Investigations on the antiproliferative effects of amino acid antagonists targeting for aminoacyl-tRNA synthetases. Part III--Combination experiments

The combined effects of amino acid antagonists with proven or potential inhibitory activities on aminoacyl-tRNA synthetases were investigated on the murine leukemic cell line P388 D1. As the best result a summation of the antiproliferative effects was observed. Combinations with established cytostatic agents like platinum complexes or other antitumor compounds also yielded partly additive effects. In experiments performed with asparaginase L-aspartic acid-beta-hydroxamate gave synergistic growth inhibition of P388 D1 cells in vitro, which was reflected by additive effects against murine leukemia P388 in vivo.

Tumor inhibiting [1,2-bis(difluorophenyl)ethylenediamine]dichloroplatinum (II) complexes, I: Synthesis

The synthesis of the diastereomeric 1,2-bis(2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5-difluorophenyl)ethylenediamine (meso, D/L 8-13) from meso 1,2-bis(2-hydroxyphenyl)ethylenediamine and the respective difluorobenzaldehyde by a diaza-Cope-rearrangement and their conversion into the [1,2-bis(2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5-difluorophenyl)ethylenediamine]dihaloplatinum(II)- complexes (meso, D/L 8-13 PtCl2; meso D/L 9- and 11-PtI2) with K2PtHal4 (Hal = Cl, I) is described. From the diiodoplatinum(II)-complexes (meso D/L 9- and 11-PtI2) the better water soluble diaqua[1,2-bis(2,4- and 2,6-difluorophenyl)ethylenediamine]platinum(II) sulfates (meso, D/L 9- and 11-PtSO4) are obtained by reaction with Ag2SO4.

Tumor-inhibiting [1,2-bis(fluorophenyl)ethylenediamine]platinum(II) complexes. V. Synthesis and evaluation of enantiomeric [1,2-bis-(4-fluorophenyl)ethylenediamine]dichloroplatinum(II) complexes

The enantiomeric [1,2-bis(4-fluorophenyl)ethylenediamine]dichloroplatinum(II) complexes were synthesized and tested on the hormone-sensitive human MCF7 breast cancer cell line and on the P388 leukemia of the mouse. They showed a strong and comparable activity on both tumor models.

Aqua[1-(2,6-dichloro-4-hydroxyphenyl)-2- phenylethylenediamine](sulfato)platinum-(II) complexes with variable substituents in the 2-phenyl ring. 1. Synthesis and antitumor and estrogenic properties

Erythro- and threo-configurated aqua[1-(2,6-dichloro-4-hydroxyphenyl)-2- phenylethylenediamine](sulfato)platinum(II) complexes with variable substituents in the 2-phenyl ring (2-PtSO4 to 9-PtSO4: H, 4-F, 3-OH, 4-OH, 2,6-F2, 2,6-Cl2, 2-F/4-OH, 2-Cl/4-OH) were synthesized and tested for estrogenic and antitumor activities. The ligands were obtained by a three-step reaction. The stilbenes were reacted with a mixture of IN3 and NaN3 to yield the respective 1,2-diazido-1,2-diphenylethanes. The subsequent reduction with LiAlH4 led to the corresponding 1,2-diphenyl-ethylenediamines. The (sulfato)platinum(II) complexes were synthesized by reaction of Ag2SO4 with the diiodo complexes, which had been obtained by coordination of the diamines with K2PtI4. Two complexes, erythro-8-PtSO4 and erythro-9-PtSO4, possess antitumor and estrogenic effects and are therefore of interest for the therapy of breast cancer.

Computerized determination of growth kinetic curves and doubling times from cells in microculture

In this paper we describe the microcomputer-aided determination of cell proliferation kinetics and doubling times utilizing a crystal violet assay and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay in microtitration plates. The analysis of spectrophotometric data provides the doubling times at any time of incubation. Plots of doubling time versus time of incubation give reproducible information on the exact duration of the logarithmic growth phase. This method is applicable to anchorage-dependent as well as anchorage-independent cells when colorimetric or fluorometric data are accessible.

[DL-1,2-bis(2-hydroxyphenyl)ethylenediamine]dichloroplatinum(II), a new compound for the therapy of ovarian cancer

The synthesis of diastereoisomeric [1,2-bis(2-hydroxyphenyl)ethylenediamine]dichloroplatinum(II) complexes, DL-3-PtCl2 and meso-3-PtCl2, and their evaluation on the hormone-independent, human MDA-MB231 breast cancer cell line, on the cisplatin-sensitive and -resistant L1210 leukemia cell line, on the cisplatin-resistant human NIH:OVCAR 3 ovarian cancer cell line, on the P-388 leukemia of the mouse and on the cisplatin-sensitive and -resistant Ehrlich ascites tumor of the mouse are described. On all tumor models DL-3-PtCl2 produces a marked inhibitory effect. The diastereoisomer meso-3-PtCl2 is less active and more toxic. It is striking that DL-3-PtCl2 leads to a pronounced inhibition of all cisplatin-resistant tumors. At non-toxic concentrations DL-3-PtCl2 produces cytocidal effects on the NIH:OV-CAR 3 cell line. Therefore DL-3-PtCl2 is of interest for further evaluation for the therapy of ovarian cancer.

Tumor inhibiting [1,2-bis(fluorophenyl)ethylenediamine]platinum(II) complexes, III: Evaluation of the mammary tumor inhibiting properties

Diastereomeric diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]platinum(II) sulfates and nitrates produce a strong inhibition of the hormone-dependent MXT-M 3.2 mammary carcinoma of the B6D2F1 mouse. Besides an interference in the DNA synthesis in analogy to cisplatin a lowering of the estrogen level due to an interference in steroid biosynthesis is suggested as the mode of action. In contrast to the R,R/S,S configurated diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]platinum(II) salts the corresponding R,S configurated compounds are also markedly active on the hormone-independent MXT-Ovex mammary carcinoma of the B6D2F1 mouse.

[Antiestrogenic N-(4-hydroxyphenyl)-n-(1,1,1,-trifluoro-2-propyl)-4- hydroxybenzamides: influence of hydrophobic groups substituted in the ortho-position of the benzamide-fragment on activity]

Experiments are reported here to develop compounds with antiestrogenic and mammary tumor inhibiting properties. Analogues with hydrophobic groups in 2- or 2,6-position of the benzamide-fragment of N-(4-hydroxyphenyl)-N-(1,1,1-trifluoro-2-propyl)- 4-hydroxybenzamides were investigated. Compounds 2 and 3 proved to be "true" antiestrogenes among 2-7 (2: 2-CH3, 3: 2-F, 4: 2-Cl, 5: 2-Br, 6: 2,6-Cl2, 7: 2-CF3). Compound 4 showed the highest activity on the MXT-MC, ER+.