Biological Properties of Cell Lines Derived from Moloney Virus-Induced Sarcoma

Two cell lines derived from a primary MSV-M-induced tumor in a BALB/c mouse were studied. One line (MS-2) was subject only to continuous tissue culture transfer (tct). After 21 tct, MS-2 cells produced progressive tumors (MS-2 tumors) in syngeneic hosts. The second cell line (MS-2T) was established by cultivation of a MS-2 tumor. The ability to produce progressive tumors decreased with increased number of tct, in both cell lines. The virus content of MS-2 and MS-2T cells was very low, as shown by uridine incorporation and electron microscopy. Immunofluorescence tests demonstrated that antigens different from the viral MSV-M antigens were present on the cell lines, and that antigenic changes occurred with increased number of tct. Serum of mice bearing progressive MS-2 tumors reacted with MS-2T cells when these cells produced progressive tumors and did not react with MS-2 cells when they produced regressing tumors. MS-2 cells producing regressing tumors reacted with serum from mice in which the MS-2 tumor had regressed and with serum from mice immunized with MS-2T cells at late tct when they were poorly oncogenic. The antigenic changes seemed, therefore, to parallel the decrease of malignancy. A chromosomal analysis carried out on MS-2 and MS-2T cells, when both produced progressive tumors, showed a modal number of 48 and 44, respectively. MS-2T cells showed a large acrocentric chromosome. In contrast, the MS-2 cells at late tct, when they gave regressing tumors, showed a modal number of 60 and a wide range of distribution of chromosome number.

Effect of Daunorubicin and Adriamycin on Nucleic ACID Synthesis of Serum Stimulated Mouse Embryo Fibroblasts

This paper reports the effects of daunorubicin and adriamycin on DNA and RNA synthesis of in vitro cultured mouse embryo fibroblasts (MEF) stimulated by fetal calf serum (FCS). The addition of FCS to quiescent MEF cultures brings about a wave of RNA synthesis, followed by DNA synthesis which starts between 8 and 12 h after change of medium and proceed for up to 24 h. These cells are therefore partially synchronized. The level of DNA synthesis depends on the amount of FCS added. Daunorubicin and adriamycin are almost equally effective in inhibiting DNA synthesis, as well as cell proliferation, which takes place later. Adriamycin is more active than daunorubicin on RNA synthesis. In cultures treated for an 8 h period starting at different times after FCS addition, the highest DNA synthesis inhibition is achieved by treatment during the first 8 h, when DNA synthesis has not yet started. The cellular uptake of daunorubicin is constantly higher than that of adriamycin, in any experimental condition tested. The results show that FCS-stimulated MEF can provide a simple method for studying the effects of anthracycline antibiotics on partially synchronized cells.

Tumors and Dental and Ocular Abnormalities after Treatment of Infant Rats with Adriamycin

In rats repeatedly treated subcutaneously as infants with adriamycin in 2 cycles of 4 treatments each, the induction of ocular and dental abnormalities and tumors was studied. Cataracts appeared from 18 to 26 days in 80 % of CD rats treated with 1.15 mg/kg/day of adriamycin and from 28 to 104 days in 55 % of Wistar-Lewis rats given 0.75 mg/kg/day adriamycin. Abnormal growth of incisors was observed in 30 % of the CD rats and in 44 % of the Wistar-Lewis rats. At lower doses, no such abnormalities were found. At about 1 year after treatment, 100 % of the CD rats treated with 0.75 mg/kg/day adriamycin and about 60 % of the Wistar-Lewis rats treated with 0.75 and 0.5 mg/kg/day adriamycin developed tumors, which were histologically classified.

Antileukemic Activity of 4-Demethoxydaunorubicin in Mice

4-demethoxydaunorubicin was tested against experimental mouse leukemias, in comparison with doxorubicin and daunorubicin. 4-demethoxydaunorubicin, administered ip to mice bearing ascitic L1210 or F388 leukemia was 5 times more potent than daunorubicin and 10 times more potent than doxorubicin (potency established in relation to optimal antitumor doses). At the optimal doses, 4-demethoxydaunorubicin was as active as daunorubicin and less active than doxorubicin. 4-demethoxydaunorubicin, administered iv was 8 times more potent than daunorubicin and 4–5 times more potent than doxorubicin. At the optimal doses, 4-demethoxydaunorubicin was markedly more active than daunorubicin or doxorubicin in mice injected iv with 105 L1210 leukemia cells (early or late leukemia) or with 102 Gross leukemia cells. In mice given 2 × 106 Gross leukemia cells iv, 4-demethoxydaunorubicin was as active as doxorubicin when treatment was given iv on day 1, or on days 1 to 3 or 1 to 5. The optimal intermittent schedule was treatment on days 1, 5 and 9 for 4-demethoxydaunorubicin, and on days 1, 3 and 6 for daunorubicin and doxorubicin. 4-demethoxydaunorubicin administered orally was highly active against ascitic P388 leukemia and against L1210 and Gross leukemia inoculated iv.

Combined Effect of Influenza Virus Infection and Urethan Treatment on the Incidence of Lung: Tumors in Mice

Swiss mice were intranasally infected with influenza A2 virus and treated with urethan in order to detect whether the joint action of the two agents would enhance the development of lung tumors. The average number per mouse of the typical lesions induced by the two treatments together with their location, their histological and histochemical characteristics and the percentage of death in the different groups of animals were recorded. Results indicated that 51.7 % of the mice infected with influenza virus and treated with urethan had both bronchial dysplastic lesions due to influenza virus, and tumors induced by urethan. In this group the number of tumors was smaller than in the mice treated with the carcinogen only and no invasive pulmonary carcinomas were observed. The dysplastic lesions caused by influenza A2 virus as well as the lung adenomas induced by urethan maintained their typical histological and histochemical characteristics even when occurring in a close position. The failure of urethan to enhance the induction of lung tumors in mice exposed to influenzal infection might be ascribed to the different primary sites of response of the pulmonary tissue to the two agents, i.e. the bronchial epithelium for influenza virus and the alveolar epithelium for urethan.

Enhancement of the Antitumor Activity of Adriamycin by Tween 80

This paper describes the effect of Tween 80 on the antitumor activity and on the distribution of adriamycin in mice. The dilution of adriamycin in a 10% water solution of Tween 80 produced a significant increase of the antitumor activity in mice against ascites tumors (L1210 leukemia), disseminated leukemias (transplanted leukemias originally induced by Gross leukemia virus and Moloney leukemia virus), and solid tumors (Sarcoma 180, MS-2 sarcoma). In all these experiments the drug was administered i.v., according to different schedules. Higher antitumor activity at the optimal dose and an increase of activity at lower doses were observed in different experimental systems. Toxicity was also slightly enhanced. Tissue distribution was studied in normal mice and in tumor-bearing mice (Gross leukemia and MS-2 sarcoma). In animals given i.v. adriamycin diluted in 10% Tween 80 there was a higher drug concentration in spleen, lung and kidney than there was in mice given the drug in a water solution. In all the other organs examined (heart, liver, small intestine) and in the MS-2 tumor tissue, no significant increase was observed. In L1210 leukemia-bearing mice, i.p. treatment with adriamycin diluted in 10% Tween 80 resulted in a significantly higher toxicity than that which resulted from treatment with adriamycin in a water solution; no increase of antitumor activity was observed.

Satraplatin, an oral platinum analog, is active and synergistic with paclitaxel and docetaxel in prostate carcinoma models

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Background: Satraplatin is a novel oral platinum analog with potent cytotoxic and antitumor activity in preclinical models. Satraplatin showed activity in hormone refractory prostate cancer (HRPC) and other tumor types in Phase II trials. A pivotal Phase III trial evaluating satraplatin as 2nd-line therapy for HRPC completed accrual of > 900 patients in 2005. Satraplatin’s activity, safety profile and ease of administration make it attractive for combination regimens. Methods: Satraplatin and its active metabolite JM-118 were tested in vitro as single agents in the androgen-sensitive LNCaP and the androgen-insensitive PC-3 and DU-145 human prostate carcinoma (ca.) cell lines. For in vitro combination studies, PC-3 cells were treated with satraplatin or JM-118 either prior to, after, or concomitantly with paclitaxel or docetaxel. The PC-3 cell line was used for in vivo xenograft experiments in nude mice. Paclitaxel was given intravenously on Day 1, satraplatin orally on Days 2 to 6, and paclitaxel again on Day 8. Results: Satraplatin and JM-118 as single agents inhibited the growth of all three prostate ca. cell lines in vitro in a dose dependent fashion. IC50 values for JM-118 were < 1μM. Strong synergism was noted when PC-3 tumor cells were treated in vitro with paclitaxel or docetaxel followed by satraplatin or JM-118. Satraplatin administered orally inhibited the growth of PC-3 xenografts in nude mice. Treatment of advanced PC-3 tumors with paclitaxel (40 mg/kg) and satraplatin (35 mg/kg) was well tolerated and resulted in a Tumor Growth Delay equivalent to 3 Log Cell Kill, an effect superior to that of the single agents. Conclusions: In vitro, satraplatin and its metabolite JM-118 are active as single agents against human prostate ca. cells, and are synergistic with taxanes. In vivo, treatment with paclitaxel followed by satraplatin showed synergism without increased toxicity. These preclinical data support ongoing Phase I and II clinical trials that are evaluating combinations of satraplatin with paclitaxel or docetaxel.

[Table: see text]

BAY 12-9566, a novel inhibitor of matrix metalloproteinases with antiangiogenic activity

Matrix metalloproteinases (MMPs) have been implicated in tumor cell invasion, metastasis, and angiogenesis. BAY 12-9566, a novel, non-peptidic biphenyl MMP inhibitor, has shown preclinical activity on a broad range of tumor models and is currently in clinical development. The purpose of this study was to investigate the antiangiogenic activity of BAY 12-9566. In vitro, BAY 12-9566 prevented matrix invasion by endothelial cells in a concentration-dependent manner (IC50 = 8.4x10(-7) M), without affecting cell proliferation. In vivo, oral daily administration of BAY 12-9566 (50-200 mg/kg) inhibited angiogenesis induced by basic fibroblast growth factor in the Matrigel plug assay, reducing the hemoglobin content of the pellets. Histological analysis showed a reduction in the amount of functional vessels within the Matrigel. We conclude that the MMP inhibitor BAY 12-9566 inhibits angiogenesis, a property that further supports its clinical development as an antimetastatic agent.

Naamidine A is an antagonist of the epidermal growth factor receptor and an in vivo active antitumor agent

The known 2-aminoimidazole alkaloid naamidine A (1) was isolated from a Fijian Leucetta sp. sponge as an inhibitor of the epidermal growth factor (EGF) receptor. The compound exhibited potent ability to inhibit the EGF signaling pathway and is more specific for the EGF-mediated mitogenic response than for the insulin-mediated mitogenic response. Evaluation in an A431 xenograft tumor model in athymic mice indicated that naamidine A exhibited at least 85% growth inhibition at the maximal tolerated dose of 25 mg/kg. Preliminary mechanism of action studies indicate that the alkaloid fails to inhibit the binding of EGF to the receptor and has no effect on the catalytic activity of purified c-src tyrosine kinase.

Eleutherobin, a novel cytotoxic agent that induces tubulin polymerization, is similar to paclitaxel (Taxol)

Eleutherobin is a novel natural product isolated from a marine soft coral that is extremely potent for inducing tubulin polymerization in vitro and is cytotoxic for cancer cells with an IC50 similar to that of paclitaxel. This compound is cross-resistant along with other multidrug-resistant agents against P-glycoprotein-expressing cells and is cross-resistant with paclitaxel against a cell line that has altered tubulin. In mechanistic studies, eleutherobin shares with paclitaxel the ability to induce tubulin polymerization in vitro and is most likely cytotoxic by virtue of this mechanism. Human colon carcinoma cells exposed to eleutherobin contain multiple micronuclei and microtubule bundles, and they arrest in mitosis, depending on concentration, cell line, and length of exposure. These morphological abnormalities appearing in cultured cells are indistinguishable from those induced by paclitaxel. Electron microscopy reveals that eleutherobin induces homogeneous populations of long, rigid microtubules similar to those formed by paclitaxel. Thus, eleutherobin is a new chemotype with a mechanism of action similar to that of paclitaxel and, as such, has promising potential as a new anticancer agent.

Doxorubicin disaccharide analogue: apoptosis-related improvement of efficacy in vivo

BACKGROUND

Although doxorubicin remains one of the most effective agents for the treatment of solid tumors, there is an intensive effort to synthesize doxorubicin analogues (compounds with similar chemical structures) that may have improved antitumor properties. We have synthesized a novel doxorubicin disaccharide analogue (MEN 10755) and have characterized some of its relevant biochemical, biologic, and pharmacologic properties.

METHODS

The antitumor activity of this compound (MEN 10755) was studied in a panel of human tumor xenografts, including xenografts of A2780 ovarian tumor cells, MX-1 breast carcinoma cells, and POVD small-cell lung cancer cells. MEN 10755 was compared with doxorubicin according to the optimal dose and schedule for each drug. The drug's cytotoxic effects, induction of DNA damage, and intracellular accumulation were studied in A2780 cells. DNA cleavage mediated by the enzyme topoisomerase II was investigated in vitro by incubating fragments of simian virus 40 DNA with the purified enzyme at various drug concentrations and analyzing the DNA cleavage-intensity patterns. Drug-induced apoptosis (programmed cell death) in tumors was determined with the use of MX-1 and POVD tumor-bearing athymic Swiss nude mice.

RESULTS

MEN 10755 was more effective than doxorubicin as a topoisomerase II poison and stimulated DNA fragmentation at lower intracellular concentrations. In addition, MEN 10755 exhibited striking antitumor activity in the treatment of human tumor xenografts, including those of the doxorubicin-resistant breast carcinoma cell line MX-1.

CONCLUSIONS

The high antitumor activity of MEN 10755 in human tumor xenografts, including doxorubicin-resistant xenografts, and its unique pharmacologic and biologic properties make this disaccharide analogue a promising candidate for clinical evaluation.

Effect of linker variation on the stability, potency, and efficacy of carcinoma-reactive BR64-doxorubicin immunoconjugates

The internalizing anti-Le(y) monoclonal antibody (MAb) BR64 was conjugated to the anticancer drug doxorubicin (DOX) using an acid-labile hydrazone bond to the DOX and either a disulfide or thioether bond to the MAb. The resulting disulfide (BR64-SS-DOX) and thioether (BR64-S-DOX) conjugates were evaluated for stability, potency, and antigen-specific activity in both in vitro and in vivo model systems. The BR64-SS-DOX conjugates demonstrated antigen-specific activity both in vitro and when evaluated against antigen-expressing, DOX-sensitive human carcinoma xenografts. However, the stability and potency of disulfide conjugates were poor, and in vivo activity superior to unconjugated DOX was seen only at doses approaching the maximum tolerated dose. Furthermore, BR64-SS-DOX conjugates were not active against antigen-expressing, DOX-insensitive colon tumor xenografts. In contrast, the BR64-S-DOX conjugates demonstrated good stability both in vitro and in vivo. The increased stability of the BR64-S-DOX conjugates resulted in the delivery of more biologically active DOX to tumors with a concomitant increase in potency and efficacy over that which could be achieved with either unconjugated DOX or BR64-SS-DOX conjugates. Delivery of DOX by BR64-SS-DOX conjugates resulted in complete regressions and cures of both DOX-sensitive lung xenografts and DOX-intensitive colon tumor xenografts. These results demonstrate the importance of linker stability when delivering drugs such as DOX to carcinomas via internalizing antibodies and are likely to have direct relevance to the clinical utility of MAb-directed delivery.

Preclinical antitumor activity of water-soluble paclitaxel derivatives

PURPOSE

Five water-soluble paclitaxel derivatives were extensively evaluated for their antitumor activities relative to the parent drug.

METHODS

Both subcutaneous (s.c.) murine (M109 lung) and human (A2780 ovarian, L2987 lung) tumor models were used for this purpose.

RESULTS

Consecutive daily intravenous (i.v.) paclitaxel therapy of mice bearing s.c. M109, beginning on day 4 or 5 posttumor implant and continuing for 5 days, resulted in a range of maximum gross log cell kill (LCK) values (reflective of delays in tumor growth) and maximum relative median survival time (% T/C) values (reflective of increases in lifespan) of 1.0-2.1 and 132-162% (and one outlying result of 235%), respectively. Against the same tumor model, using the same treatment schedule, each of the water-soluble derivatives was active, with maximum LCK of 1.3-2.5 and T/C of 124-254%. These LCK and %T/C values were always within 0.5 LCK and 15%, respectively, of the concomitantly obtained maximum effects of paclitaxel. When tested in several experiments against staged (50-100 mg) s.c. A2780 tumors, using various i.v. treatment schedules, the water-soluble derivatives achieved a maximum LCK of 1.4-3.8. Evaluated in parallel, paclitaxel achieved a maximum LCK of 2.1-4.5 following every other day x 5 i.v. therapy. When paclitaxel was assayed in several experiments using the staged (50-100 mg) s.c. L2987 tumor model, maximum LCK of 0.9->4.1 were produced following every other day x 5 i.v. therapy. Concomitant testing of the water-soluble derivatives, using the same i.v. treatment schedule, resulted in maximum LCK of 0.2->4.1. In each of the tumor models used, the consistently active, and usually the most active, water-soluble derivative was BMS-185660. The levels of activity observed were comparable (within 1 LCK) to those achieved concomitantly using paclitaxel, and its potency was only slightly inferior to the parent drug.

CONCLUSIONS

Based on the evaluations performed in three distal site tumor models, we conclude that BMS-185660 is a water-soluble paclitaxel derivative with preclinical antitumor activity comparable to that of the parent drug.

Paclitaxel (Taxol(R)) inhibits motility of paclitaxel-resistant human ovarian carcinoma cells

The effect of paclitaxel on the adhesive and motility properties of human ovarian carcinoma cell lines was investigated. Paclitaxel significantly inhibited the motility of OVCAR 5, SK-OV-3, and HOC-1OTC ovarian carcinoma cell lines (IC50 = 2.1 x 10(-8), 2 x 10(-9), and 1.9 x 10(-8) m, respectively) but did not affect the adhesion of these cells to the subendothelial matrix. The association between inhibition of motility and cytotoxic activity was investigated using an A2780 subclone (1A9) and three paclitaxel-resistant variants (designated 1A9/PTX22, 1A9/PTX10, and 1A9/PTX18). Although paclitaxel did not significantly affect the adhesion to subendothelial matrix of the sublines, it completely inhibited their migration. Inhibition of migration was similar in 1A9 cells and the resistant sublines, with an IC50 of 1 x 10(-8) for 1A9 cells and 5.4 x 10(-9), 1.1 x 10(-8), and 5.2 x 10(-9) m for 1A9/PTX22, 1A9/PTX10, and 1A9/PTX18, respectively. Paclitaxel inhibited motility induced by soluble attractant (chemotaxis) and immobilized attractant (haptotaxis). Inhibition of cell motility occurred in the absence of an antiproliferative effect, because higher concentrations of paclitaxel were required to inhibit tumor cell proliferation (IC50 = 1.9 x 10(-7) and 4.6 x 10(-6), 1 x 10(-5), and 3.1 x 10(-6) m for 1A9 and 1A9/PTX22, 1A9/PTX10, and 1A9/PTX18, respectively). These data show that paclitaxel is a potent inhibitor of ovarian carcinoma cell motility and that this activity is independent of its cytotoxic activity.

Reversal of the human and murine multidrug-resistance phenotype with megestrol acetate

MA is an orally active PG derivative with an excellent safety profile that is used primarily for the treatment of carcinomas of the breast and endometrium. We investigated the potential application of MA as an MDR-reversal agent using cell culture and human tumor xenograft models. The reversing activity of MA in vitro was compared with that of PG and VER in two human MDR cell lines, the colon carcinoma HCT-116/VM46 and the breast carcinoma MCF-7/ADR, and in a murine cell line, J774.2. At concentrations as low as 3 microM, MA was capable of partially restoring sensitivity to Act D in the HCT-116/VM46 cells and sensitivity to DOX in the MCF-7/ADR cells. Although less effective than VER, MA was about 2.5 times more potent than PG in reversing MDR at equimolar concentrations. Increased accumulation of DOX in drug-resistant cells that were treated simultaneously with MA was observed by flow cytometry. In vivo, using established human colon and breast carcinoma xenografts implanted s.c. in athymic mice, the combined therapy with MA and DOX resulted in enhanced antitumor activity relative to that of DOX alone in the MDR sublines. These results suggest that MA may be a promising clinical MDR-reversing agent.

Structure-activity relationships of VP-16 analogues

A total of 27 selected analogues of VP-16 and VM-26 were compared with VP-16 and VM-26 for their relative abilities to stabilize the enzyme-substrate intermediate normally formed between eukaryote topoisomerase II and DNA. This activity was compared with cytotoxicity results obtained using the human colon HCT116 cell line and antitumor results obtained after intraperitoneal injection of mice with murine leukemia P388. The most potent analogues were those containing OH groups (demethyl) in either the 3' and 4' or the 3', 4', and 5' positions, the latter being twice as potent as VP-16. VM-26 was only 40% more potent than VP-16 in this assay. It was generally found that the 4'-esters had little activity in vitro, yet were cytotoxic and had antitumor activities. All other analogues with little in vitro activity were not very cytotoxic and had little if any antitumor activity. A very good correlation exists between stabilization of topoisomerase II-DNA intermediates, cytotoxicity, and antitumor activity.

Selective proteolytic activity of the antitumor agent kedarcidin

Kedarcidin is a potent antitumor antibiotic chromoprotein, composed of an enediyne-containing chromophore embedded in a highly acidic single chain polypeptide. The chromophore was shown to cleave duplex DNA site-specifically in a single-stranded manner. Herein, we report that in vitro, the kedarcidin apoprotein, which lacks any detectable chromophore, cleaves proteins selectively. Histones that are the most opposite in net charge to the apoprotein are cleaved most readily. Our findings imply that the potency of kedarcidin results from the combination of a DNA damaging-chromophore and a protease-like apoprotein.

Cure of xenografted human carcinomas by BR96-doxorubicin immunoconjugates

Immunoconjugates (BR96-DOX) were prepared between chimeric monoclonal antibody BR96 and the anticancer drug doxorubicin. The monoclonal antibody binds an antigen related to Lewis Y that is abundantly expressed at the surface of cells from many human carcinomas; it has a high degree of tumor selectivity and is internalized after binding. BR96-DOX induced complete regressions and cures of xenografted human lung, breast, and colon carcinomas growing subcutaneously in athymic mice and cured 70 percent of mice bearing extensive metastases of a human lung carcinoma. Also, BR96-DOX cured 94 percent of athymic rats with subcutaneous human lung carcinoma, even though the rats, like humans and in contrast to mice, expressed the BR96 target antigen in normal tissues.

Kedarcidin chromophore: an enediyne that cleaves DNA in a sequence-specific manner

Kedarcidin chromophore is a 9-membered enediyne, recently isolated from an actinomycete strain. In vivo studies show this molecule to be extremely active against P388 leukemia and B16 melanoma. Cytotoxicity assays on the HCT116 colon carcinoma cell line result in an IC50 value of 1 nM. In vitro experiments with phi X174, pM2 DNA, and 32P-end-labeled restriction fragments demonstrate that this chromophore binds and cleaves duplex DNA with a remarkable sequence selectivity producing single-strand breaks. The cleavage chemistry requires reducing agents and oxygen similar to the other naturally occurring enediynes. Certain cations (Ca2+ and Mg2+) prevent strand cleavage. High-resolution 1H NMR studies on the chromophore in the presence of calcium chloride implicate the 2-hydroxynaphthoyl moiety in DNA binding. Interestingly, the kedarcidin chromophore appears structurally related to neocarzinostatin yet recognizes specific DNA sequences in a manner similar to calicheamicin gamma 1I, an enediyne with a significantly different structure. Moreover, kedarcidin and calicheamicin share a DNA preferred site, the TCCTN-mer. These observations indicate that the individual structural features of these agents are not solely responsible for their DNA selectivity. Rather, a complementarity between their overall tertiary structure and the local conformation of the DNA at the binding sites must play a significant role in the recognition process.

Preclinical antitumor activity of orally administered platinum (IV) complexes

Several novel platinum (IV) mixed ammine/amine dicarboxylate dichlorides of general structure [Pt(IV)Cl2(OCOY)2NH3(XNH2)], where Y is aliphatic or aromatic and X is alicyclic or aliphatic, known to be particularly well absorbed following oral administration, were evaluated by that route for their antitumor activity. Testing of the Pt(IV) derivatives took place concomitantly with i.v. administered cisplatin and carboplatin in two s.c. staged tumor models, the murine M5076 sarcoma and human A2780 ovarian carcinoma. Based upon repetitive experiments which included an evaluation of different vehicles and treatment schedules, each of the orally administered Pt(IV) dicarboxylates was reproducibly active in the M5076 tumor, producing mean maximum gross log cell kill (LCK) values of between 1.5 and 2.0, and lifespan increases, reflected by mean maximum treated/control median survival (T/C) values, of 139-151%. Cisplatin and carboplatin given i.v. yielded mean maximum LCK of 3.5 and 2.5, respectively, as well as mean maximum T/C values of 166% and 164%, respectively, in the same tumor model. The best of the derivatives in the M5076 experiments, JM-216 [ammine/cyclohexylamine diacetato dichloride Pt(IV)], produced LCK values that averaged only 0.5 lower than that of carboplatin, and increases in lifespan not significantly different than that of carboplatin. Against the A2780 tumor, the Pt(IV) dicarboxylates produced individual best effects of between 0.8-1.1 LCK, based on data from two or three experiments. The mean maximum LCK values for cisplatin and carboplatin were 1.8 and 2.2 LCK, respectively. JM-225, ammine/cyclopentylamine diacetato dichloride Pt(IV), was active in two of three experiments, including one result comparable to that of carboplatin. The Pt(IV) mixed ammine/amine dicarboxylate dichlorides represent a novel class of Pt derivative capable of expressing oral antitumor activity in both murine and human tumor models.

Mechanisms of resistance to etoposide and teniposide in acquired resistant human colon and lung carcinoma cell lines

Stable acquired resistance to etoposide (VP-16) or teniposide (VM-26) in HCT116 human colon carcinoma cells and A549 human lung adenocarcinoma cells, was previously obtained by weekly 1-h exposures to either drug (B. H. Long, Natl. Cancer Inst. Monogr., 4: 123-127, 1987). The purpose of this study was to identify possible mechanisms of resistance present in these cells by using human mdr1 and topoisomerase II DNA probes, antibodies to these gene products, and P4 phage unknotting assay for topoisomerase II activities. HCT116(VP)35 cells were 9-, 7-, and 6-fold resistant to VP-16, VM-26, and Adriamycin, respectively, and showed no cross-resistance to colchicine and actinomycin D. These cells had no differences in mdr1 gene, mdr1 mRNA, or P-glycoprotein levels but displayed decreased levels of topoisomerase II mRNA and enzyme activity without any alteration of drug sensitivity displayed by the enzyme. HCT116(VM)34 cells were 5-, 7-, and 21-fold resistant to VP-16, VM-26, and Adriamycin; were cross-resistant to colchicine (7-fold) and actinomycin D (18-fold); and possessed a 9-fold increase in mdr1 mRNA and increased P-glycoprotein without evidence of mdr1 gene amplification. No alterations in topoisomerase II gene or mRNA levels, enzyme activity, or drug sensitivity were observed. A549(VP)28 and A549(VM)28 cells were 8-fold resistant to VP-16 and VM-26 and 3-fold resistant to Adriamycin. Both lines were not cross-resistant to colchicine or actinomycin D but were hypersensitive to cis-platinum. No alterations in mdr1 gene, mdr1 mRNA, or P-glycoprotein levels, but lower topoisomerase II mRNA levels and decreased enzyme activities, were observed. Of the four acquired resistant cell lines, resistance is likely related to elevated mdr1 expression in one line and to decreased topoisomerase II expression in the other three lines.

Preclinical antitumor activity of a soluble etoposide analog, BMY-40481-30

BMY-40481-30 is a new, water-soluble derivative and probable prodrug of etoposide characterized by the presence of a phosphate group in position 4' of the E ring of the etoposide molecule. The compound was only weakly cytotoxic in vitro and, consequently, an investigation of its antitumor activity was conducted in several murine and human tumor (xenograft) models. Etoposide was administered ip or po whereas BMY-40481-30 was given ip, po or iv. The potency of the derivative, when administered parenterally, as defined on the basis of maximum tolerated dose (MTD), was less than the parent compound on a weight (mg/kg) basis in some experiments but comparable to etoposide in other instances. Comparison at the MTD of the two compounds showed that BMY-40481-30 administered ip was as active as etoposide against ip P388 leukemia. BMY-40481-30 given iv was more active than etoposide given ip in two of five experiments versus iv P388 leukemia, but the two compounds were comparably active in the other three studies. Of particular interest was the finding that the derivative was more active than the parent compound at many of the comparable (on a mg/kg basis) dose levels of both evaluated po versus iv P388 leukemia; MTD levels were not achieved, and hence not compared, for either compound using the po route of administration. Both etoposide and BMY-40481-30 yielded comparable maximum effects against ic P388 leukemia, ic L1210 leukemia, and sc B16 melanoma, but etoposide was more efficacious versus sc M5076 sarcoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical and biological characterization of 4'-iodo-4'-deoxydoxorubicin

4'-Iodo-4'-deoxydoxorubicin is a doxorubicin (DXR) analogue with greater lipophilicity and reduced basicity of the amino group. In vitro 4'-iodo-4'-deoxydoxorubicin is more cytotoxic than DXR against a panel of human and murine cell lines and is characterized by a higher and faster uptake. In vivo, the spectrum of activity of 4'-iodo-4'-deoxydoxorubicin is comparable to that of DXR, but the new compound has higher activity against murine P388 leukemia resistant to DXR and against pulmonary metastases from Lewis lung carcinoma. Moreover, the new analogue exhibits antitumor activity also after p.o. administration and shows no cardiotoxicity in experimental systems.

Antitumor and toxicity evaluation of free doxorubicin and doxorubicin entrapped in cardiolipin liposomes

The antitumor activity of free doxorubicin and doxorubicin entrapped in cardiolipin liposomes was evaluated in P388 ascitic leukemia, disseminated Gross leukemia, and advanced mammary carcinoma. In P388 leukemia, free drug and drug entrapped in liposomes demonstrated equivalent antitumor activity at doses of 2.2 and 4.4 mg/kg, demonstrating 52% and 69% ILS (increase in life-span), respectively. Free doxorubicin at a dose of 10 mg/kg was superior, producing a 185% ILS against 82% with liposomal doxorubicin. With an increase in administered dose the antitumor response with liposomal doxorubicin was much more pronounced; at doses of 20 and 25 mg/kg the ILS was in excess of 376%, with five of ten mice surviving tumor-free. In Gross leukemia, the optimum dose of free doxorubicin, 10 mg/kg, brought about 186% T/C (median survival in treated mice over that in controls, X 100), whereas with liposomal doxorubicin the optimum dose was 16.9 mg/kg, which yielded 214% T/C. In advanced mammary carcinoma, the maximum tumor regression with free doxorubicin was at a dose of 7.5 mg/kg, with two of six mice dying of toxicity. Liposomal doxorubicin caused maximum tumor regression at 10.8 mg/kg dose with no toxic deaths. Doxorubicin entrapped in cardiolipin liposomes was much less toxic than free drug at high doses in normal mice.

Biochemical and biological activity of the anthracycline analog, 4-demethyl-6-O-methyl-doxorubicin

The chromophore-modified derivative of doxorubicin, 4-demethyl-6-O-methyl-doxorubicin, has been tested for antitumor activity in a range of experimental murine tumor systems. In contrast to the inactive 6-O-methyl derivative of daunorubicin, 4-demethyl-6-O-methyl-doxorubicin provided antitumor effects comparable to that of the parent compound. In addition, detailed DNA-interaction studies showed that the doxorubicin derivative retains the ability to bind DNA by the intercalation mechanism. However, the binding affinity was appreciably reduced following structural modification in the anthraquinone chromophore. On the basis of the proposed models of intercalation, these results could be rationalized in terms of steric influence of the bulky methoxy group. The results of this study are in agreement with the correlation already observed between DNA binding and relative antitumor activity of anthracyclines.

New anthracycline glycosides obtained by the nitrous acid deamination of daunorubicin, doxorubicin and their configurational analogues

The new anthracyclines 7-O-(2,3,5-trideoxy-3-C-formyl-alpha-L-threo-pentofuranosyl)daunomyci none (8) and -adriamycinone (10) have been obtained upon nitrous acid deamination of daunorubicin and doxorubicin respectively. Deamination of the L-ribo analogue of daunorubicin (6) gave a mixture of 2,3,6-trideoxy-L-glycero-hexopyranosid-4-ulose (alpha-L-cinerulosyl) (11) and 2,6-dideoxy-alpha-L-arabino-hexopyranosyl (12) glycosides. The corresponding adriamycinone glycosides 13 and 14, obtained by deamination of the doxorubicin L-ribo analogue 7, were found to display an outstanding antileukemic activity in mice.

Combined and sequential treatment using FCE 21336, a new prolactin-lowering drug, and medroxyprogesterone acetate (MPA) in DMBA-induced tumors in rats

The effect of the new, prolactin-lowering ergoline derivative FCE21336 and medroxyprogesterone acetate (MPA) given alone and in combination was tested on DMBA-induced mammary tumors in rats. FCE 21336 (0.05 and 0.4 mg/kg p.o.) and MPA (25 and 50 mg/kg s.c.), administered 5 days/week for 4 weeks, inhibited the growth of established tumors and reduced serum prolactin levels. Combined treatment inhibited tumor growth more than single treatment. These results were confirmed in a second experiment: the antitumor effect of the combination of FCE 21336 (0.1 mg/kg p.o.) and MPA (50 mg/kg s.c.) was greater than that of the single treatment and was similar to the effect of ovariectomy. In this experiment rats with tumors that did not respond to 4 weeks' treatment with FCE 21336 (0.1 mg/kg p.o.) were treated during the next 4 weeks with MPA (50 mg/kg s.c.). MPA was effective on FCE 21336-unresponsive tumors. These data indicate that combined FCE 21336 and MPA treatment is more effective than single treatment and that MPA is effective on tumors not sensitive to the prolactin-lowering drug.

Synthesis, antitumor activity, and cardiac toxicity of new 4-demethoxyanthracyclines

The new anthracycline glycosides 4-demethoxy-4'-deoxydaunorubicin and 4-demethoxy-4'-O-methyldaunorubicin, synthesized by coupling 4-demethoxydaunomycinone with 1-chloro-derivatives of protected 4-O-methyl and 4-deoxydaunosamine derivatives, have been converted into the corresponding doxorubicin analogs. The new compounds have been compared for antitumor effect with the parent drugs and with the previously described 4-demethoxydaunorubicin, 4-demethoxy-4'-epidaunorubicin, and their doxorubicin analogs. All of the new analogs were more cytotoxic against HeLa cells in vitro and were more toxic and more potent in mice than the parent drugs. Comparison at optimal antitumor doses showed that the new analogs were as active as the parent drugs against ascitic P388 leukemia and disseminated Gross leukemia. They were also active when administered orally. The new doxorubicin analogs were slightly more active than doxorubicin against ascitic L1210 leukemia and were markedly more active against disseminated L1210 leukemia. In a parallel activity-cardiotoxicity test in C3H mice repeatedly treated iv, 4-demethoxydoxorubicin, 4-demethoxy-4'-epidoxorubicin, 4-demethoxy-4'-O-methyldoxorubicin, and 4-demethoxy-4'-deoxydoxorubicin showed antitumor activity against mammary carcinoma without inducing the typical myocardial lesions observed after doxorubicin treatment, 4-Demethoxy-4'-O-methyldoxorubicin, because of its high antitumor effectiveness, lack of cardiac toxicity in mice, and activity by the oral route, deserves further study.

Antitumor activity in mice of 4'-deoxydoxorubicin in comparison with doxorubicin

4'-Deoxydoxorubicin has been compared with doxorubicin as regards potency, antitumor activity and toxicity in tumored and non-tumored mice treated i.v. according to different schedules. 4'-Deoxydoxorubicin was 1.5-3 times more toxic and more potent than doxorubicin. At equitoxic doses, 4'-deoxydoxorubicin was: as active as doxorubicin against Gross leukemia, mammary carcinoma and MS-2 sarcoma; slightly less active than doxorubicin against B16 melanoma; more active than doxorubicin against colon 38 adenocarcinoma. The best schedule of administration of 4'-deoxydoxorubicin in mice was the weekly treatment. The strong effectiveness against colon 38 adenocarcinoma makes 4'-deoxydoxorubicin a particularly interesting new anthracycline derivative that deserves clinical trials.

Synthesis, biological and biochemical properties of new anthracyclines modified in the aminosugar moiety

New 4'-C-methyl analogues of daunorubicin, synthesized by the coupling reaction of daunomycinone with 1-chloroderivatives of protected 4-C-methyldaunosamine analogues, were chemically transformed to the corresponding doxorubicin analogues. Their cytotoxic effect against HeLa cells, ability to bind to DNA, and in vivo toxicity and antitumor activity were compared with those of daunorubicin, doxorubicin, and their 4'-O-methyl analogues. The cytotoxic effect of the new anthracyclines could be correlated with their ability to bind to DNA and with their toxicity in experimental animals; however, the antitumor effectiveness did not seem to be related to these parameters. In general all the compounds retained a remarkable antitumor activity at their optimal doses. The most active compound against P388 leukemia was 4'-O-methyldoxorubicin, which was also more active than doxorubicin against L1210 leukemia.

New anthracycline glycosides: 4-O-demethyl-11-deoxydoxorubicin and analogues from Streptomyces peucetius var. aureus

The new anthracyclines 4-O-demethyl-11-deoxydoxorubicin, 4-O-demethyl-11-deoxydaunorubicin along with its 13-dihydro and 13-deoxo analogues are the main components of the anthracycline complex produced by cultures of Streptomyces peucetius var. aureus. They were isolated by solvent partition, separated by column chromatography and characterized by chemical and physical methods. Among these new anthracyclines, displaying antibacterial and cytotoxic activity "in vitro", 4-O-demethyl-11-deoxydoxorubicin and the corresponding daunorubicin analogue were also active against experimental tumors.

Cross resistance and cellular uptake of 4'-O-methyldoxorubicin in experimental tumors with acquired resistance to doxorubicin

A new analog of doxorubicin, 4'-O-methyldoxorubicin, was previously reported to have a pronounced activity against L1210 leukemia, which shows a natural partial resistance to doxorubicin itself. In the present study, lines of P388 leukemia and Ehrlich ascites tumor with acquired resistance to doxorubicin were found to be cross-resistant to 4'-O-methyldoxorubicin, indicating that the natural and the acquired resistance to doxorubicin involve different mechanisms. In vitro studies on the uptake of 4'-O-methyldoxorubicin in the Ehrlich ascites tumor cells indicated that the observed cross-resistance was partly due to a decreased drug uptake in the resistant cells because of an increased extrusion of the drug, in accordance with previous findings on the mechanism of acquired resistance to doxorubicin.

Evaluation of new anthracycline analogs with the human tumor stem cell assay

Ten anthracyclines, including doxorubicin (DX) and daunorubicin (DNR), and eight analogs with modifications in structure or stereochemistry of the aglycone and/or the aminosugar moiety were simultaneously tested in serial vitro titration studies against human adenocarcinomas in the human tumor stem cell assay. More than a two-log range in cytotoxicity of the various anthracyclines was observed with the tumors tested. Marked individual differences in sensitivity of specific tumors (breast, lung, peritoneal) were observed for the various analogs. By assessing average effects on survival of tumor colony-forming units (TCFU) in the tumors tested, the three compounds lacking the methoxyl group in position 4 of the aglycone (4-demethoxyDX, 4-demethoxy-4'-epiDX, 4-demethoxyDNR) all proved to be more cytotoxic than their parent compounds. Compounds modified in position 4' of the aminosugar were on average either as toxic (4' epiDX) or more toxic (4'-deoxyDX and 4'-0-methylDX) to TCFU than the parent compound DX. On average, 11-deoxyDX was less toxic than DX or the other eight anthracyclines tested. The results obtained are also in good general agreement with those previously reported for anthracyclines with human tumors in xenografts or cancer patients. These antitumor results viewed in concert with toxicology studies in normal mice (including evidence of a lack of cardiac toxicity) suggest that 4'deoxyDX may prove to be a clinically useful anthracycline analog. We also conclude that use of this clinically predictive in vitro soft agar assay provides a rapid and relatively inexpensive means of simultaneously testing a large number of analogs of a parent compound against a spectrum of human tumors.

Fluorescence assays and pharmacokinetic studies of 4'-deoxydoxorubicin and doxorubicin in organs of mice bearing solid tumors

The pharmacokinetic of 4'-deoxydoxorubicin, a new analog of doxorubicin, was compared with that of its parent compound in mice treated with equal and equiactive doses. The levels of total fluorescence due to the initial drugs and to metabolites were determined in tissue extracts by fluorometry. 4'-Deoxydoxorubicin reached the same tissue levels as doxorubicin in all the organs tested except in spleen and lung, where a higher peak was found in the animals treated with the new analog. The rate of elimination of 4'-deoxydoxorubicin from the organs tested was higher than that of doxorubicin.

Studies in mice treated with ICRF-159 combined with daunorubicin or doxorubicin

We have investigated the effect of ICRF-159 on the toxicity of daunorubicin (DR) and doxorubicin (DX) given iv, and the effectiveness of ICRF-159 combined with DR or DX on the growth of transplantable MLV-M (murine leukemia virus-Moloney) leukemia, MS-2 solid sarcoma, and pulmonary MS-2 metastases in mice. The injection of ICRF-159 concurrently with the administration of DR resulted in a marked decrease in the toxicity of the antibiotic. However, when DX was injected concurrently with ICRF-159 an increase in antibiotic toxicity was observed, except when ICRF-159 was employed at a very low dosage. ICRF-159 administered alone did not influence the tumor growth in the systems tested and did not result in antimetastatic activity. In mice bearing transplanted MLV-M leukemia, the effects of the combination of ICRF-159 with DR or DX were not superior to those of DR or DX treatment on either tumor growth or lifespan. The treatment of MS-2 tumor with the ICRF-159 and DX combination neither produced a therapeutic synergism (therapeutic response superior to the maximum response obtainable by either agent independently) nor antagonized the antineoplastic action of DX. A marked inhibition of tumor growth and increase in lifespan were observed in the mice treated with a high dose of DR (10 mg/kg/injection) plus ICRF-159 (50 mg/kg/injection). We have also examined, on MS-2 lung metastases, the effectiveness of surgical-adjuvant combination chemotherapy with DR or DX plus ICRF-159 injected at different times with respect to surgery. A synergistic effect of DX or DR with ICRF-159 was observed when the drug treatment was performed before the surgery, or both before and after the surgery. No synergistic effect of DX or DR with ICRF-159 on MS-2 lung metastases was found when the MS-2 lung metastases were treated after the surgery. A higher antimetastatic activity was observed in the groups treated with a combination of toxic doses of DR and ICRF-150 than in the groups treated with a combination of toxic doses of DR and ICRF-159 than in the groups treated with tolerated doses of the antibiotic.

New anthracycline glycosides from Micromonospora. II. isolation, characterization and biological properties

Four glycosides, designated A, B, C and D, are the main components of the anthracycline complex produced by cultures of Micromonospora sp. nov. They were extracted by solvent partition, separated by column chromatography and characterized by chemical and physical methods as 11-deoxy analogues of daunorubicin. Among these new anthracyclines, displaying antibacterial and cytotoxic activity in vitro, 11-deoxydaunorubicin and 11-deoxydoxorubicin are also active against P388 leukemia in mice.

Fluorescence assay of tissue distribution of 4-demethoxydaunorubicin and 4-demethoxydoxorubicin in mice bearing solid tumors

The tissue distribution of 4-demethoxydaunorubicin and 4-demethoxydoxorubicin was studied in comparison with that of their patient compounds, daunorubicin and doxorubicin, in mice bearing transplanted tumors. The doses administered were equal or equitoxic to those of their parent compounds. The levels of total fluorescence due to initial drugs and metabolites were determined on tissue extracts by fluorometry. After administration of equal doses of daunorubicin and 4-demethoxydaunorubicin, the calculated Cxt values of 4-demethoxydaunorubicin equivalents were higher than those for daunorubicin in all the organs tested except the heart. In animals treated with equitoxic doses, lower 4-demethoxydaunorubicin levels were found in all the organs tested. In mice treated with equitoxic doses of doxorubicin and 4-demethoxydoxorubicin, 4-demethoxydoxorubicin reached higher drug concentrations than doxorubicin in spleen and liver, whereas in all the other organs tested lower drug levels were found. The rate of drug disappearance from organs was slower in animals treated with 4-demethoxyderivatives than in those treated with their parent drugs.

Experimental evaluation of anthracycline analogs

This review summarizes the preclinical tests conducted to date for experimental evaluation of new anthracycline analogs. Most of the data are derived from the experience at the Istituto Nazionale Tumori, Milan, Italy, at the National Cancer Institute, Bethesda, Md, and at the Farmitalia Research Laboratories, Nerviano, Italy. In vitro cytotoxicity tests are useful for determining the doses to be used in vivo. Antitumor activity tests in mice can be divided into different stages. P388 and L1210 leukemias are generally used in primary screening; the value of adding L1210 leukemia is briefly discussed. Other experimental tumors adopted include disseminated leukemia and transplanted solid tumors. The importance of the route and schedule of treatment is stressed. Drugs should be administered iv in the case of solid tumors, and the schedule of treatment can be adjusted according to the pharmacokinetic properties of the new analog, when these are known. If possible, the parent compound and the new analog should be dissolved in the same solvents. In the toxicity tests, cardiac toxicity deserves particular attention. Until now, the only experimental model in which a number of new anthracyclines have been tested is the rat model proposed by Zbinden. A comparison between cardiotoxicity data obtained in such models and antitumor data obtained in mice shows that cardiac toxicity can be dissociated from the antitumor activity. Knowledge of pharmacokinetic properties of new analogs is of importance for selecting the schedules of treatment and for explaining selective toxic effects.

Preliminary phase I study of 4'-epi-adriamycin

A phase I study of 4'-epi-Adriamycin (4'-epi-ADM) was performed in 22 patients with various types of advanced solid tumors. Very preliminary results would indicate that the drug produces a pattern of acute toxicity which is similar to that of Adriamycin. However, the incidence of vomiting, alopecia, and marrow suppression was less pronounced than that of Adriamycin. 4'-Epi-ADM prolonged the systolic time interval, although no patient presented clinical signs of cardiotoxicity. Two patients with renal carcinoma and malignant melanoma showed objective improvement. Present results suggest that further clinical studies with 4'-epi-ADM are indicated.

Effect of various substitutions in positions 1, 2, 3, and 4 of 4-demethoxydaunorubicin and 4-demethoxyadriamycin

Previous studies on structure-activity relationships of anthracycline antitumor antibiotics have shown that removal of the methoxyl group at position 4 of the aglycone causes a marked increase in the potency of the compounds: 4-demethoxydaunorubicin and 4-demethoxyadriamycin had an antitumor effect similar to that of the parent compound at doses five to eight times lower, and they were active even when administered orally. This paper reports the effects of further substitutions at positions 1, 2, 3, and 4 of 4-demethoxy aglycone. The introduction of methyl groups at positions 2 and 3, or 1 and 4 resulted in decreased cytotoxicity and biological activity. The addition of a benzoyl ring at positions 2 and 3 decreased the activity further. 1,4-Dichloro-4-demethoxydaunorubicin and 2,3-dichloro-4-demethoxydaunorubicin were respectively as active and 2.5 times less active than was daunorubicin against HeLa cells in vitro while they were inactive against P388 and L1210 leukemias in vivo. 2,3-Dimethyl-4-demethoxyadriamycin showed an antitumor activity against mouse leukemias that was slightly higher than was that of adriamycin.

Synthesis and antitumour activity of new daunorubicin and adriamycin analogues

A new synthetic procedure for the preparation of daunorubicin and adriamycin analogues bearing different substituents on ring D, has been developed. The new compounds display outstanding efficacy against experimental tumours of mice.