1-Amino-substituted 4-methyl-5H-pyrido[3',4':4,5]pyrrolo[3,2-c]pyridines: a new class of antineoplastic agents

In an attempt to find new anticancer agents, a series of pyrido[3',4':4,5]pyrrolo[3,2-c]pyridines were synthesized and evaluated in the standard NCI screening. Among these new compounds, which are structurally related to 9-azaellipticines but differ by deletion of a cycle, those that have a 4-methyl group and a NHCH2CH2CH2NR2 side chain at the 1-position show significant cytotoxicity on L1210 cultured cells and antitumor properties in the in vivo P388 leukemia system. The in vivo antineoplastic activity of the most potent compounds were confirmed on the L1210 leukemia model.     

Synthesis and antitumor properties of activated cyclophosphamide analogues

A series of 5- and 6-substituted cyclophosphamide analogues has been prepared, and their 31P NMR kinetics of phosphoramide mustard (PDA) release and in vitro and in vivo cytotoxicity have been evaluated. cis-4-Hydroxy-5-methoxycyclophosphamide equilibrated very slowly and to a minor extent with the ring-opened aldophosphamide analogues in aqueous buffer; release of PDA was observed to a minor extent and only at high (1 M) buffer concentrations. This analogue was essentially inactive in vitro against L1210 and P388 leukemia cells. 6-Phenylcyclophosphamide and its 4-hydroperoxy derivative were potent inhibitors of blood acetylcholinesterase and were lethal at therapeutic doses in mice. In contrast, 4-hydroperoxy-6-(4-pyridyl)cyclophosphamide did not inhibit acetylcholinesterase and showed significant antitumor activity in vitro and in vivo against both wild-type and cyclophosphamide-resistant L1210 leukemia. The 4-hydroperoxy-6-arylcyclophosphamides were generally active in vitro against both wild-type and cyclophosphamide-resistant L1210 and P388 cells, and several analogues showed significant activity in vivo. Surprisingly, there was no correlation between antitumor activity in vitro and the rate of PDA release in aqueous buffer. Several compounds that showed essentially no release of PDA in aqueous buffer over several hours were highly cytotoxic to leukemia cells following a 1-h exposure in vitro. These results show that activated cyclophosphamide analogues substituted at the 6-position are not cross-resistant in these leukemia cell lines, and that a specific intracellular activation mechanism may be catalyzing PDA release in these analogues.     

Antitumor properties of 2(1H)-pyrimidinone riboside (zebularine) and its fluorinated analogues

2(1H)-Pyrimidinone riboside (zebularine, 1b) and its 5-fluoro (6b) and 2'-ara-fluoro (7b) analogues have been synthesized and evaluated in vivo as antitumor agents. Zebularine provides increase in life span (ILS) values of ca. 70% against intraperitoneal (ip) murine B16 melanoma and 50% against P388 leukemia. This compound is active when administered either ip or orally against ip or subcutaneously implanted L1210 leukemia, producing ILS values of about 100% at an optimum dose of 400 mg/kg. 1b is also active (60% ILS) against ara-C-resistant L1210. The analogous unsubstituted purine riboside nebularine (2) has modest activity against P388 leukemia (60% ILS). While 2'-ara-fluorozebularine (7b) is only marginally active (40% ILS) at high doses against L1210 leukemia, 5-fluoro analogue 6b is more active than zebularine and is ca. 100 times more potent. Although the activity of 6b is about the same as that of 1b against P388 leukemia, greater potency also is realized in this model. Zebularine is a strong inhibitor of cytidine deaminase, but in contrast to tetrahydrouridine, 1b is acid-stable. In an attempt to use this property to advantage in oral administration, 1b and ara-C have been orally coadministered to mice with ip L1210 leukemia. When zebularine is given in divided doses, up to a 2-fold increase in activity is realized, relative to treatment with the same dose of ara-C alone.     

Antitumor spectrum of deoxyspergualin and its lack of cross-resistance to other antitumor agents

Antitumor activities of 15-deoxyspergualin (NKT-01), an analogue of spergualin (SGL), were examined in cultured tumor cells, transplantable murine tumors, and human tumor xenografts in nude mice. NKT-01 exhibited strong antitumor activity specifically against leukemias both in vitro and in vivo. Moreover, it also showed activity against AH66F hepatoma, M5076 fibrosarcoma and MH134 hepatoma. However, antitumor activity of NKT-01 against other non-leukemic tumors was marginal. Effective dose range of NKT-01 in sensitive tumors was so wide that the largest chemotherapeutic indexes were produced by NKT-01 in P388 and L1210 leukemias among 15 antitumor agents examined. The efficacy of NKT-01 against doxorubicin- and cytosine arabinoside-resistant P388 leukemias was comparable to that against parental sensitive P388 leukemia. NKT-01 also retained activity against other p388 leukemia sublines resistant to cisplatin, 5-fluorouracil or nimustine, although the effect was slightly decreased. In addition, in the in vitro and in vivo experiments using NKT-01-resistant P388 and SGL-resistant L1210(IMC) leukemias, no cross-resistance was observed. Moreover, collateral sensitivity was observed especially to alkylating agents in animal study.     

Chemical properties and biological effects of 2-haloethyl sulfonates

Data for the alkylating activities, DNA cross-linking activities, and proliferation-inhibitory activities toward cultured L1210 cells for twenty-four 2-haloethyl sulfonates are reported. Previously reported activities against P388 leukemia in vivo are also presented to permit correlation of in vitro and in vivo properties. Since these compounds are believed to be 2-haloethylating agents, their properties and effects were compared with those of chlorozotocin, which is a recognized 2-chloroethylating agent. 2-Chloroethyl chloromethanesulfonate, which was the most effective compound against P388 leukemia, had a moderate level of alkylating activity and a low level of cross-linking activity, but it was quite active in inhibiting proliferation of cultured L1210 cells. Although its alkylating activity was about the same as that of chlorozotocin, it caused much less cross-linking of DNA. The in vitro tests were useful for gaining information relating structure to the individual properties, but results obtained for one of the properties might not be predictive of the relative values obtained for other properties nor for in vivo activity against P388 leukemia. These results indicate that additional experiments to define the mechanism of action of these agents are needed.     

Synthesis and antitumor activity of a series of ftorafur analogues: the effect of varying electronegativity at the 1'-position

To test the effect of changes in electronegativity within the alicyclic N-1 substituent 5-fluorouracil analogues on cytotoxic activity, a series of derivatives of ftorafur, 1-(2'-tetrahydrofuranyl)-5-fluorouracil, was synthesized and tested for antitumor activity in the P388 lymphocytic leukemia screen and cytotoxic activity in the L1210 cell culture screen. Two compounds of N-1 substituent with high electronegativity, the 2'-tetrahydrothiophene 1'-oxide and the 2'-tetrahydrothiophene 1',1'-dioxide derivatives, demonstrated the highest in vitro L1210 cell inhibition (84.5% and 92.0%, respectively). Furthermore, against P388 lymphocytic leukemia in vivo, the 2'-tetrahydrothiophene 1'-oxide derivative showed significant activity (T/C = 143). Other compounds of similar or lower electronegativity within the N-1 cyclic substituent were inactive against P388 lymphocytic leukemia and less active against L1210 cells.     

Antineoplastic activity of didemnin congeners: nordidemnin and modified chain analogues

Nordidemnin (2), a natural analogue of the marine cyclodepsipeptide didemnin B (1b), showed cytotoxic activity against L1210 leukemia and antineoplastic activity against P388 leukemia as well as B16 melanoma; nordidemnin (2) was as active as didemnin B (1b). The influence of synthetic modifications in the linear peptidic chain on in vitro and in vivo activity was also studied. Replacement of the terminal lactyl residue by mandelyl and 3-(p-hydroxyphenyl)propionyl residues in compounds 3 and 4, respectively, did not affect the cytotoxic activity against L1210 leukemia (ID50 of 1.1 nM and 1.2 nM, respectively) or the in vivo activity against P388 leukemia. Unlike these aromatic substituants, the lipophilic palmityl residue induced a dramatic loss in cytotoxic activity. The inverted chirality of the MeLeu joining residue in compound 6 caused a marked reduction in the in vitro activity.     

Didemnin B

A new class of marine compounds, the didemnins, with potent antitumor activity has been identified. They share the novel structure of a cyclic depsipeptide. Among three structurally related compounds, didemnin B is by far the most potent in its in vitro cytotoxicity and in vivo antitumor activity (0.001 g/ml inhibits the growth of L1210 leukemia cells by 50%). It also demonstrates good antitumor activity against B16 melanoma and moderate activity against M5076 sarcoma and P388 leukemia. The compound also has good antiviral and potent immunosuppressive properties. Although the precise mechanism of action for the cytotoxicity remains unknown, the agent inhibits protein synthesis more than DNA synthesis and the inhibition of protein synthesis is closely correlated with inhibition of L1210 cell growth. Toxicology studies in CD2F1 mice, Fischer 344 rats and beagle dogs reveal that major target organs are the lymphatics, gastrointestinal tract, liver and kidney. Phase I trials are currently in progress under the auspices of the National Cancer Institute.     

Antitumor effects of biologic reducing agents related to 3,4-dihydroxybenzylamine: dihydroxybenzaldehyde, dihydroxybenzaldoxime, and dihydroxybenzonitrile

This report describes a structure-activity analysis of isomers of three classes of dihydroxybenzene derivatives, including dihydroxybenzaldoxime, dihydroxybenzaldehyde, and dihydroxybenzonitrile. These derivatives were examined for their effect on ribonucleotide reductase activity, macromolecular synthesis, cell growth, and in vivo antitumor activity against the L1210 murine leukemia. One of the compounds studied exhibited significant antitumor activity against the growth of L1210 leukemia cells. A comparison of the various analogues revealed a possible correlation for 3,4-dihydroxybenzaldoxime between its potent inhibitory effect toward ribonucleotide reductase activity (IC50 = 38 microM) and its superior L1210 antitumor activity [percent increased life span (% ILS) = 100].     

Doxorubicin analogues incorporating chemically reactive substituents

Doxorubicin (1) analogues 2-5, incorporating the following alkylating or latent alkylating substituents, R, on the 3'-position of the daunosamine sugar have been synthesized as potential antitumor agents: 2, R = NHCOC6H4(p)SO2F; 3, R = NHCOCH2Br; 4, R = NHCOCH2Cl; 5, R = NHCON(NO)CH2CH2Cl. These compounds were designed on the premise that alkylating anthracyclines might bind covalently to critical intracellular target macromolecules and overcome resistance to the parent agent attributable to reduced cellular drug accumulation. Growth inhibitory studies of the analogues were conducted in vitro against mouse leukemia cells (L1210 and P388) and human uterine sarcoma cells that are sensitive (MES-SA) and resistant (MES-SA/DOX) to doxorubicin. The analogues were 5-100-fold less potent than doxorubicin against the sensitive cell lines. However, they were only marginally cross-resistant with doxorubicin against MES-SA/DOX. Compounds 3 and 5 were also evaluated against a human myelocytic cell line (KBM-3) and a subline (KBM-3/DOX) resistant to doxorubicin. They were equally potent against both cell lines, indicating a complete lack of cross-resistance with doxorubicin. Alkylating anthracyclines may have potential for the treatment of tumors resistant to the parent agents.     

Pyrimidoacridine derivatives as potential antitumor agents.

A series of some N-alkylaminoalkyl derivatives of pyrimido[5,6,1-d,e]acridine-1,3,7-trione (3) was synthesized as new potential antitumor drugs, starting from the suitable 9,10-dihydro-9-oxo-4-acridinecarboxamides and using phosgene as cyclizing agent. 1-(9,10-dihydro-9-oxo-4-acridinecarbonyl)-3-alkyl-2-imidazolido nes were also obtained as side products. The final products 3 and some carboxamides were tested "in vitro" against L 1210 leukemia and "in vivo" against P388 leukemia. Of the tested compounds, one is active "in vivo", another shows significant cytotoxic activity "in vitro", but is inactive or toxic "in vivo".     

In vivo antitumor activity of 6-benzyl-1,3-benzodioxole derivatives against the P388, L1210, B16, and M5076 murine models

A series of 6-benzyl-1,3-benzodioxoles have been synthesized and evaluated against the in vivo ip P388 murine lymphocytic leukemia. Selected activities against this system were tested against the additional in vivo systems L1210, B16, M5076, and MX1. The most active of the 6-benzyl-1,3-benzodioxoles tested were as effective as podophyllotoxin as experimental antitumor agents in vivo, but larger doses were required. Three of the P388-active series members were active against the in vitro astrocytoma assay, which detects compounds that interfere with or bind to tubulin.     

In vivo antitumor activity of 4-amino 4-methyl 2-pentyne 1-al, an inhibitor of aldehyde dehydrogenase

4-amino-4-methyl-2-pentyne-1-al (AMPAL), a new irreversible inhibitor of aldehyde dehydrogenase (ALDH) has been assayed for its in vitro and in vivo antitumor activity. In vitro, AMPAL inhibits the proliferation and the ALDH activity of L1210 and RBL5 cell lines. In vivo, AMPAL significantly increases the mean survival time of mice i.p. grafted with leukemia (L1210, P815, MBL2, EL4, RBL5 cell lines) or carcinoma cells (Krebs cell line), without haematopoetic toxicity. No carcinostatic effect was observed against the P388 leukemia and the 3LL Lewis lung carcinoma. A possible relationship between the ALDH isoenzyme activity of the tumor and its sensitivity to AMPAL is discussed in the light of previous reports concerning the role of aldehydes in cell growth control.     

Potential central nervous system antitumor agents. Aziridinylbenzoquinones. 1.

A series of 3,6-substituted 2,5-diaziridinyl-1,4-benzoquinones was prepared as potential CNS antitumor agents. Activity was evaluated in the murine leukemia L1210 system. The diurethane derivative 9 was found to have significant activity in that system as well as in the intraperitoneal P388 and B16 tumor models. Marginal Lewis lung activity was observed. Reproducible activity was seen in the intracerebral L1210 and P388 systems. Multiple cures were observed in the murine ependymoblastoma brain tumor model. The effect of substituent type on aziridinylquinone activity is discussed.     

Antitumor activity of benzamide riboside and its combination with cisplatin and staurosporine

Benzamide riboside (BR), a new synthetic nucleoside analogue, has demonstrated a potent cytotoxic activity in murine leukemia in vitro. The purpose of the present investigation was to examine the antitumor activity of BR in mice bearing leukemia L1210. The results revealed that BR possesses a potent antitumor activity in vivo. It increases life-span of mice with leukemia. Synergistic cytotoxicity of BR with select DNA damaging agents, cisplatin (cis-Pt) and staurosporine (STP) was examined in MTT chemosensitivity assay, FACS analyses and apoptotic DNA fragmentation on L1210 cells in culture. A simultaneous treatment of leukemia L1210 cells with the combination of BR and STP resulted in synergistic cytotoxicity that correlated with increased apoptotic activity in those cells. On the other hand, treatment of L1210 cells with combination of BR and cis-Pt resulted in antagonistic cytotoxic effect. Finally, to elucidate the synergistic effect of BR and STP in inducing apoptosis, the attention was directed to the activation of cell death processes through various cell cycle signals. This is the first report describing in vivo antitumor activity of BR and its utilization in combination chemotherapy.     

Heterocyclic quinones. 17. A new in vivo active antineoplastic drug: 6,7-bis(1-aziridinyl)-4-[[3-(N,N-dimethylamino)propyl]amino]-5,8- quinazolinedione

A series of heterocyclic quinones, 6-substituted and 6,7-disubstituted 4-(alkylamino)-5,8-quinazolinediones, have been synthesized in order to evaluate their in vitro cytotoxicity on L1210 leukemia cells. Among 14 derivatives that have been prepared and studied for the structure-activity relationship, the most potent cytotoxic compound on L1210 leukemia cells was the 6,7-bis(1-aziridinyl)-4-[[3-(N,N-dimethylamino)propyl]amino]-5,8- quinazolinedione (24). This compound has been tested with the use of a cell-image processor on MCF-7 human mammary and HBL human melanoma cell lines. The results show that compound 24 influences cell proliferation and blocks both cells lines in the S phase. In vivo antineoplastic activity of compound 24 has been demonstrated on a broad spectrum of murine experimental models, but it was found highly toxic and produced long-delayed deaths.     

Cross-resistance of drug-resistant murine leukemias to deoxyspergualin (NSC 356894) in vivo

Deoxyspergualin, the 15-deoxy derivative of the antibiotic spergualin, is a novel guanidino analog structurally related to spermine. Deoxyspergualin has significant activity in selected experimental tumor models, and clinical trials have been initiated. Described here are in vivo evaluations of the therapeutic activity of deoxyspergualin against murine leukemia lines specifically resistant to eight clinically useful antitumor drugs. These were P388 lines resistant to doxorubicin, vincristine, L-phenylalanine mustard, cisplatin, ara-C, and methotrexate and L1210 lines resistant to 5-FU, L-phenylalanine mustard, and cyclophosphamide. Sensitivity to deoxyspergualin was evaluated in parallel comparisons of each resistant leukemia to the sensitive line from which it had been derived. All experiments were repeated at least once for confirmation of results. Responses were quantitated in terms of the change in tumor cell numbers from the beginning of treatment to the end of treatment as estimated from the median survival times of dying mice. The results indicated that P388 leukemia resistant to cisplatin (P388/DDPt) was cross-resistant to deoxyspergualin. No cross-resistance was observed in leukemias resistant to doxorubicin, vincristine, ara-C, methotrexate, or cyclophosphamide. L1210 resistant to 5-FU (L1210/5-FU) was collaterally sensitive to deoxyspergualin. Although cross-resistance was also observed in P388/L-PAM, L1210/L-PAM retained sensitivity to deoxyspergualin. Total glutathione concentrations in P388/L-PAM and L1210/L-PAM provided no apparent explanation for this unexpected result. It may be tentatively concluded that resistance to cisplatin, L-PAM, or other DNA alkylators or cross-linkers may increase the potential for cross-resistance to deoxyspergualin. This conclusion requires verification with additional alkylating agents, with drug-resistant human tumor cell lines, and with prospective clinical studies.(ABSTRACT TRUNCATED AT 250 WORDS)     

Synthesis of hydroxy- and amino-substituted benzohydroxamic acids: inhibition of ribonucleotide reductase and antitumor activity.

Benzohydroxamic acids inhibit mammalian ribonucleotide reductase and exhibit antineoplastic activity in L1210 leukemic mice. Five new hydroxy- and amino-substituted benzohydroxamic acids (3,4- and 3,5-OH, 3,4-NH2, 2,3,4- and, 3,4,5-OH) were prepared and tested along with 12 previously reported benzohydroxamic acids (BHA) for enzyme inhibition and antitumor activity. The most potent enzyme inhibitor in this series was 2,3,4-OH-BHA (ID50 = 3.5 microM), which is 140 times more potent than hydroxyurea, but its toxicity limited the antitumor activity to a 30% increase in life span of L1210 bearing mice at 125 (mg/kg)/day ip for 8 days. The most effective antitumor agent in this series was 3,4-OH-BHA which prolonged the life span of L1210 bearing mice 103% at 600 (mg/kg)/day ip for 8 days.     

Antitumor and DNA-binding properties of a group of oligomeric complexes of Pt(II) and Pt(IV)

The antitumor and DNA-binding properties of a group of oligomeric platinum(II) and platinum(IV) complexes are described. The compounds, having the stoichiometry [cis-PtII(X)2(mu-OH)]2(NO3)2, where X is NH3, NH2CH2CH3, and NH2CH(CH3)2, were found to be inactive or only weakly active against L-1210 leukemia. In vitro studies involving PM2-DNA show that these compounds bind to and unwind closed circular DNA in a manner similar to cis-PtII-(NH3)2Cl2. The Pt(IV) complexes produced by hydrogen peroxide oxidation of the Pt(II) dimers are inactive as antitumor agents and are incapable of unwinding PM2-DNA. The cyclotrimer [cis-PtII(RR-DACH)(mu-OH)]3(NO3)3, where RR-DACH is (R,R)-1,2 diaminocyclohexane, exhibits potent antitumor activity against L-1210 leukemia and modest activities with B-16 and M5076 tumor lines. This compound platinates DNA, causing DNA unwinding and mobility shifts.     

Tallysomycin, a new antitumor antibiotic complex related to bleomycin. III. Antitumor activity of tallysomycins A and B.

The antitumor activity of tallysomycins A and B was determined in five experimental tumor systems in mice. Tallysomycins A and B were highly active against B16 melanoma, sarcoma 180 ascites tumor and Lewis lung carcinoma, and moderately active against P388 leukemia but were without effect on lymphoid leukemia L1210. The antitumor activity of tallysomycin A was 2 to 3 times that of tallysomycin B and 3 to 17 times that of bleomycin. Tallysomycin A was about 1.5 and 4 times more toxic for mice than tallysomycin B and bleomycin, respectively, in terms of subacute LD50 values.