Carbonate and carbamate derivatives of 4-demethylpenclomedine as novel anticancer agents

Purpose  The purpose of this investigation was to synthesize a series of carbonate and carbamate derivatives of 4-demethylpenclomedine (DM-PEN), the major plasma non-toxic metabolite of penclomedine (PEN) seen in patients. DM-PEN has been observed to be an active antitumor agent in mouse human xenograft tumor models and non-neurotoxic in a rat model, however, activity in intracranially implanted human glioma xenograft models have not been reported. The major goal was to identify derivatives that are active in brain tumors. Methods  Derivatives were prepared from DM-PEN and evaluated in vivo against human U251 glioblastoma, D54 glioblastoma and MX-1 breast tumor xenografts and mammary tumor 16/C that were implanted in the mammary fat pad or intracranially (IC). Results  Carbonate and carbamate derivatives were found to be superior to DM-PEN against IC growing human glioblastoma xenografts. Conclusion  The activity of the carbonates and carbamates against human tumor xenografts in vivo suggests consideration of these two series of derivatives of DM-PEN for clinical development.     

Acyl derivatives of demethylpenclomedine, an antitumor-active, non-neurotoxic metabolites of penclomedine

PURPOSE: The purpose of this investigation was to compare the antitumor activities of a series of acyl derivatives of 4-demethylpenclomedine (DM-PEN), the major plasma metabolite of penclomedine (PEN) observed to be an active antitumor agent in vivo and non-neurotoxic in a rat model with that of DM-PEN. METHODS: Acyl derivatives were prepared from DM-PEN and evaluated in vivo against human MX-1 breast tumor xenografts implanted subcutaneously (s.c.) or intracerebrally (i.c.). Several derivatives were also evaluated against other human tumor xenografts and murine P388 leukemia cell lines. RESULTS: Several of the acyl derivatives were found to be superior to DM-PEN against MX-1, human ZR-75-1 breast tumor, human U251 CNS tumor and the P388 leukemia parent cell line and lines resistant to cyclophosphamide and carmustine. 4-Demethyl-4-methoxyacetylpenclomedine showed inferior activity to current clinical brain tumor drugs against a glioma cell line, superior activity to temozolomide and procarbazine against the derived mismatch repair-deficient cell line, and superior activity to cyclophosphamide and carmustine but inferior activity to temozolomide against two ependymoma cell lines, all of which were implanted s.c. CONCLUSION: Proposed mechanisms of activation and action of DM-PEN and the acyl derivatives support the potential clinical superiority of the acyl derivatives.     

FK317: a novel substituted dihydrobenzoxazine with potent antitumor activity which does not induce vascular leak syndrome

Purpose: FK973, a substituted dihydrobenzoxazine, is an antitumor antibiotic which has shown high therapeutic efficacy in a phase I study, but its development has been abandoned because of the side effect of vascular leak syndrome (VLS) in the clinical study. This study was performed to investigate whether or not FK317, a new benzmethoxy derivative of FK973, retains the antitumor activity of FK973 without the side effect of VLS. Methods: VLS was evaluated by the volume of pleural effusion in rats. Cytotoxic activities were determined by a tetrazolium-based colorimetric assay (MTT assay) against murine (B16, P388) and human (HeLa S3, KB) tumor cell lines. Antitumor activities against murine ascitic leukemia (P388, L1210), murine solid tumors (reticulum cell sarcoma M5076, Colon 38 carcinoma) and human xenografts (mammary carcinoma MX-1, lung carcinoma LX-1) were examined. Results: FK973 (1.8 mg/kg) given i.v. to rats induced pleural effusion, one of the elements of VLS, 36 days after the first dosing, but did not 28 days after dosing. This model reflects clinical VLS delayed-type effusion with high protein concentrations. In contrast, FK317 (1.0–3.2 mg/kg) did not induce pleural effusion at all. FK317 had stronger cytotoxic effects against in vitro cultured B16, P388, HeLa S3 and KB tumor cell lines, and in in vivo experiments, FK317 showed equivalent antitumor activity against P388, M5076 and MX-1, and more potent antitumor activity against L1210, Colon 38 and LX-1 compared with FK973. Conclusion: These results suggest that FK317 retains the antitumor activity of FK973 and does not induce VLS, and FK317 is a drug with high clinical potential for treating tumors in humans. Received: 22 May 1997 / Accepted: 12 November 1997     

In vivo Antitumor Activity of Hexamethylmelamine against Human Breast, Stomach and Colon Carcinoma Xenografts

We have evaluated the antitumor activity of Altretamine (hexamethylmelamine, HMM) on human carcinoma xenografts serially transplanted in nude mice. Five human breast carcinoma xenografts, MX-1, T-61, MCF-7, R-27 and Br-10, were inoculated subcutaneously into female nude mice. Two human stomach carcinoma xenografts, SC-1-NU and St-4, and three human colon carcinoma xenografts, Co-3, Co-4 and Co-6, were inoculated subcutaneously into male nude mice. One pellet of 17β-estradiol (0.1 mg/mouse) was inoculated subcutaneously in the mice transplanted with MCF-7 when the tumors were inoculated. HMM was administered per os daily for 4 weeks. MX-1 and T-61 tumors regressed completely after treatment with HMM at a dose of 75 mg/kg (the maximum tolerated dose: MTD) for MX-1 and 25 mg/kg for T-61. Br-10 was sensitive, whereas MCF-7 and R-27 were resistant to HMM at its MTD. HMM exerted the most potent antitumor effect against T-61. Against MX-1, it exerted an antitumor effect equivalent to that of cisplatin or cyclophosphamide. In addition, this agent was effective against all stomach and colon carcinoma xenografts, in particular St-4 (T/C%= 10.7: the mean tumor weight of treated group/the mean tumor weight of control group) and Co-3 (T/C%=31.5%) which are insensitive to presently available agents. HMM seems worthy of further clinical investigation as a candidate agent to treat breast, stomach, colon and other carcinomas.     

Antitumor activity of cryptophycins: effect of infusion time and combination studies

Introduction/Purpose: Cryptophycins are a family of antitubulin antitumor agents. A synthetic cryptophycin derivative (LY355703, CRYPTO 52) is in early clinical evaluation. The effect of infusion time on the antitumor activity of four cryptophycins was assessed in rats bearing the 13762 mammary carcinoma and combination treatment regimens were assessed in nude mice bearing human tumor xenografts. Methods: The cryptophycins were prepared in 2% PEG300/8% cremophor/90% normal saline and delivered by jugular vein catheter on days 7, 9 and 11 post tumor implant to 13762 tumor-bearing rats. The cryptophycins prepared in the same formulation were administered by intravenous bolus injection on an alternate day schedule for five doses to human tumor xenograft bearing nude mice. Results: An infusion time of 2 h in the rats increased the tumor growth delay produced by CRYPTO 52 and CRYPTO 55, while increasing the infusion time to 6 h continued to increase the tumor growth delay for CRYPTO 292 and CRYPTO 296. Administering CRYPTO 292 at a higher dose two times was more effective than administering it at a lower dose three times. The tumor growth delays produced by the cryptophycins in the rat 13762 mammary carcinoma were greater than those with cisplatin, doxorubicin, 5-fluorouracil and 5 × 3 Gray and comparable with cyclophosphamide and gemcitabine. Combination studies were carried out in human tumor xenografts including the MX-1 breast carcinoma, the Calu-6 non-small cell lung carcinoma, the H82 small cell lung carcinoma and the SW-2 small cell lung carcinoma. CRYPTO 52 and CRYPTO 55 combined with doxorubicin, paclitaxel and 5-fluorouracil to form highly effective regimens against the human MX-1 breast carcinoma. CRYPTO 52 and CRYPTO 55 were also highly effective against the three lung carcinoma xenografts when combined with the antitumor platinum complexes, cisplatin, carboplatin or oxaliplatin. Conclusions: Cryptophycins represent a promising new class of antitumor agents that may be optimally administered by intravenous infusion and in combination with doxorubicin, paclitaxel and 5-fluorouracil. Received: 18 November 1999 / Accepted: 16 March 2000     

Potent and broad antitumor effects of DX-8951f, a water-soluble camptothecin derivative, against various human tumors xenografted in nude mice

Purpose: We have previously reported that DX-8951f, a water-soluble and nonprodrug camptothecin (CPT) derivative, exhibits both high in vitro potency against a series of 32 malignant cell lines and significant topoisomerase I inhibition. The purpose of this study was to evaluate the therapeutic efficacy of DX-8951f against human tumor xenografts in nude mice and to compare its activity with those of CPT-11 and other current CPT derivatives. Methods: The antitumor activity of DX-8951f against xenografts of several different types of human tumors was determined in nude mice using a schedule in which DX-8951f was administered intravenously every 4th day for a total of four injections. Results: Against both gastric adenocarcinoma SC-6 and its CPT-11-resistant variant, SC-6/CPT-11, DX-8951f demonstrated superior antitumor activity and antitumor activity over a broader range of doses than did CPT-11, SK&F104864 (hycamtin, topotecan) and GG-211 (GI147211). DX-8951f at 75 mg/kg was effective (growth inhibition rate IR58%) against 15 of 16 lines of human cancers examined (6 colon cancers, 5 lung cancers, 2 breast cancers, 1 renal cancer and the above 2 gastric cancers), and exhibited excellent antitumor activity (IR80%) against 14 of these lines. CPT-11 exhibited antitumor activity with IR values of 58% and higher against 11 lines and IR values of 80% and higher against only eight of the same 16 human tumors. DX-8951f was effective in inhibiting the growth of an SN-38-resistant tumor and some P-glycoprotein-expressing tumors, but CPT-11 was not. Conclusions: DX-8951f exhibited potent antitumor activity against various types of human tumor xenografts. Its in vivo antitumor effects were superior to those of current camptothecin analogs against certain tumors. Received: 3 June 1997 / Accepted: 25 November 1997     

Antitumor activity and cross-resistance of carmethizole hydrochloride in preclinical models in mice

Summary Carmethizole hydrochloride [1-methyl-2-methylthio-4,5-bis(hydroxymethyl)imidazole-4,5-bis(N-methylcarbamate)hydrochloride, NSC 602 668; hereafter called carmethizole] is a new antitumor drug that has shown relatively broad activity in initial evaluations against several murine tumors and human tumor xenografts in vivo. The present studies were designed to address questions about carmethizole's activity against established disease, its activity on different treatment schedules, and the extent of its cross-resistance with established drugs. Human MX-1 mammary carcinoma, human NCI-H82 small-cell lung carcinoma, and human LOX amelanotic melanoma xenografts in athymic mice were used to determine the drug's activity against established disease; the NCI-H82 lung-tumor xenograft in athymic mice was used to explore its schedule dependence; and a series of drug-resistant murine leukemias provided an in vivo cross-resistance profile. When injected i.p., carmethizole exhibited antitumor activity against advanced-stage s.c. MX-1 mammary, s.c. NCI-H82 lung, and i.p. LOX melanoma xenografts and was as effective against established disease (MX-1 and LOX) as it was against early-stage disease (no data are available for early-stage NCI-H82). The therapeutic effect of carmethizole was not route-dependent, as was evidenced by the similar delays observed in tumor growth following i.p. and i.v. administration. The use of a split-dose schedule on a single day instead of one bolus injection yielded an increase in the total dose delivered, resulting in an increased delay in tumor growth. Murine leukemias resistant to vincristine (VCR), amsacrine (AMSA), or methotrexate (MTX) were not cross-resistant to carmethizole. However, murine leukemias resistant to doxorubicin (ADR), melphalan (l-PAM), cisplatin (DDPt), l--d-ara-binofuranosylcytosine (ara-C), and 5-fluorouracil (5-FU) were cross-resistant to carmethizole, suggesting that patients who have previously been treated with any of these agents might be less likely to respond to carmethizole than those who have had no opportunity to develop resistance to any of these compounds. We anticipate that the information derived from these studies may be useful in the design of clinical trials of carmethizole and may stimulate additional basic research on the mechanism of action of this new agent.This work was supported by contract NO1-CM-07315 with the Developmental Therapeutics Program, Division of Cancer Treatment, NCI     

UCN-01 (7-hydoxystaurosporine) inhibits in vivo growth of human cancer cells through selective perturbation of G1 phase checkpoint machinery.

Mechanisms underlying tumor sensitivity to the antitumor agent UCN-01 (7-hydroxystaurosporine) were examined in the nude mouse model using three human tumor xenografts, two pancreatic cancers (PAN-3-JCK and CRL 1420) and a breast cancer (MX-1). UCN-01 antitumor activity was evaluated in terms of relative tumor weights in treated and untreated mice bearing the tumor xenografts. The activity of cyclin-dependent kinase 2 (CDK2), levels of p21 and p27 proteins, pRb status and cell cycle were evaluated. Induction of p21 and apoptosis were also assessed immunohistochemically in CRL 1420. UCN-01 was administered intraperitoneally at a dose of either 5 or 10 mg / kg daily for 5 days followed by a further 5 injections after an interval of 2 days. UCN-01 significantly suppressed the growth of both pancreatic cancers, but was ineffective against MX-1. p21 protein expression was markedly induced in the UCN-01-sensitive pancreatic carcinoma xenografts at both doses, but p21 induction was only evident in the UCN-01-resistant MX-1 at 10 mg / kg. MX-1 exhibited CDK2 activity that was 6-fold higher than that of pancreatic cancer strains, which may explain the resistance of MX-1 to UCN-01 despite the induction of p21 at the dose of 10 mg / kg. The UCN-01-sensitive tumors exhibited G1 arrest and increased levels of apoptosis, changes not observed in resistant MX-1. In conclusion, it appears that a determining factor of in vivo UCN-01 sensitivity involves the balance of CDK2 kinase activity and p21 protein induction, resulting in augmented pRb phosphorylation, G1 cell cycle arrest and apoptosis.     

Antitumor activity on murine tumors of a novel antitumor benzoylphenylurea derivative,HO-221

Summary A novel antitumor compound,N-[4-(5-bromo-2-pyrimidinyloxy)-3-chlorophenyl]-N-(2-nitrobenzoyl) urea (HO-221) was evaluated for its antitumor activity in experimental tumor models. HO-221 preparation was given orally to tumor-bearing animals. The compound exhibited significant effects against various tumors such as P388 and L1210 leukemias; M5076 reticulum-cell sarcoma; colon 38 carcinoma; human xenografts MX-1, LX-1, GA-1, and Co-1; Lewis lung carcinoma; sarcoma 180; and Walker 256 carcinosarcoma and was especially effective against solid tumors. However, its effect on murine B16 melanoma was moderate. Intermittent administration of HO-221 produced better results. The effects of HO-221 on human tumor xenografts were compared with those of other antitumor agents. HO-221 showed activity against LX-1 lung and Co-1 gastrointestinal tumor and was also effective against advanced-stage L1210 leukemia and Lewis lung carcinoma. Furthermore, the effect of HO-221 on drug-resistant tumors was examined using murine leukemias L1210 and P388. It showed no cross-resistance with the known antitumor agents Adriamycin (ADM), daunomycin (DM), vincristine (VCR), mitomycin C (MMC), cisplatin (CDDP), 5-fluorouracil (5-FU), cytosine arabinoside (Ara-C), methotrexate (MTX), cyclophosphamide (CPA), or carboquone (CQ), and collateral sensitivity to HO-221 was found in MMC-, CDDP-, and CPA-resistant sublines. HO-221 exhibits significant reproducible, broadspectrum antitumor activity against experimental tumors as well as human neoplasms.     

Preclinical antitumor activity of penclomedine in mice: cross-resistance, schedule dependence, and oral activity against tumor xenografts in brain

Penclomedine is 3,5-dichloro-2,4-dimethoxy-6-(trichloromethyl)pyridine (NSC 338720), an alpha-picoline derivative with p.o. antitumor activity in preclinical leukemia and solid tumor models. Described here are an in vivo cross-resistance profile of penclomedine, treatment schedule dependence studies, and studies exploring the effects of p.o. drug on human tumors xenografted into mouse brain. The latter studies exploited the apparent facile distribution of penclomedine to the central nervous system. Tumor models used included murine leukemia lines selected in vivo for acquired resistance to various antitumor drugs and the human mammary and lung tumor xenografts MX-1 and H82, respectively. The therapeutic effects of p.o. penclomedine against s.c. MX-1 and H82 xenografts were shown to be independent of treatment schedule. Therapeutic activity was comparable when p.o. and parenteral treatments were compared. Lines of P388 leukemia resistant to melphalan, cyclophosphamide, and carmustine were cross-resistant to penclomedine in vivo. Leukemia lines resistant to antimetabolites, DNA binders/intercalators, and vincristine were not cross-resistant to penclomedine. Intracerebrally implanted MX-1 xenografts retained their sensitivity to p.o. penclomedine, and therapeutic activity was at least comparable to that of carmustine, a drug known for its ability to cross the blood-brain barrier. These results demonstrate attributes of penclomedine that are relatively uncommon among currently available antitumor drugs and that are of interest for the anticipated clinical development of this drug.     

UCN-01 (7-Hydoxystaurosporine) Inhibits in vivo Growth of Human Cancer Cells through Selective Perturbation of G1 Phase Checkpoint Machinery

Mechanisms underlying tumor sensitivity to the antitumor agent UCN-01 (7-hydroxystaurosporine) were examined in the nude mouse model using three human tumor xenografts, two pancreatic cancers (PAN-3-JCK and CRL 1420) and a breast cancer (MX-1). UCN-01 antitumor activity was evaluated in terms of relative tumor weights in treated and untreated mice bearing the tumor xenografts. The activity of cyclin-dependent kinase 2 (CDK2), levels of p21 and p27 proteins, pRb status and cell cycle were evaluated. Induction of p21 and apoptosis were also assessed immuno-histochemically in CRL 1420. UCN-01 was administered intraperitoneally at a dose of either 5 or 10 mg/kg daily for 5 days followed by a further 5 injections after an interval of 2 days. UCN-01 significantly suppressed the growth of both pancreatic cancers, but was ineffective against MX-1. p21 protein expression was markedly induced in the UCN-01-sensitive pancreatic carcinoma xenografts at both doses, but p21 induction was only evident in the UCN-01-resistant MX-1 at 10 mg/kg. MX-1 exhibited CDK2 activity that was 6-fold higher than that of pancreatic cancer strains, which may explain the resistance of MX-1 to UCN-01 despite the induction of p21 at the dose of 10 mg/kg. The UCN-01-sensitive tumors exhibited G1 arrest and increased levels of apoptosis, changes not observed in resistant MX-1. In conclusion, it appears that a determining factor of in vivo UCN-01 sensitivity involves the balance of CDK2 kinase activity and p21 protein induction, resulting in augmented pRb phosphorylation, G1 cell cycle arrest and apoptosis.     

Antitumor mechanisms and metabolism of the novel antitumor nucleoside analogues, 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)cytosine and 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)uracil

The antitumor ribonucleoside analogues 1-(3-C-ethynyl-β-d-ribo-pentofuranosyl)cytosine (ECyd) and 1-(3-C-ethynyl-β-d-ribo-pentofuranosyl)uracil (EUrd), first synthesized in 1995, have strong antitumor activity against human cancer xenografts without severe side effects. Here, we studied the antitumor mechanisms of ECyd and EUrd using mouse mammary tumor FM3A cells in vitro and the mechanism of selective cytotoxicity of ECyd using human tumor xenografts in nude rats in vivo. In FM3A cells, ECyd and EUrd were rapidly phosphorylated to ECyd 5′-triphosphate (ECTP) and EUrd 5′-triphosphate (EUTP), which strongly inhibiting RNA synthesis. Cells treated with EUrd were later found to contain both EUTP and ECTP, and ECTP accumulated as the final product. Probably the uracil moieties of EUrd derivatives were efficiently converted to cytosine moieties in the cells. EUrd and its derivatives were minor metabolites in the cells treated with ECyd, so cytidine forms probably were not converted to uridine forms at the nucleoside or nucleotide stage. The ultimate metabolite of ECyd and EUrd, ECTP, is stable in cultured cells with a half-life of at least 3 days, so ECyd and EUrd are on a “closed” metabolic pathway to ECTP. These characteristics of ECyd and EUrd may be important for their antitumor activity. ECyd had strong and selective antitumor activity against the human tumor xenografts. ECyd-phosphorylating activity (uridine/cytidine kinase) in the xenografts was higher than that in the organs of the rats. This finding may account for the strong activity with mild side effects. ECyd and EUrd may be a new kind of antitumor nucleoside analogue for clinical use. Received: 8 June 1998 / Accepted: 5 November 1998     

A novel carbazole topoisomerase II poison,ER-37328: potent tumoricidal activity against human solid tumors in vitro and in vivo

We have discovered a novel topoisomerase II (topo II) poison, ER-37328 (12,13-dihydro-5-[2-(dimethylamino)ethyl]-4H-benzo[c]py-rimido[5,6,1- jk ]carbazole-4,6,10(5H, 11H)-trione hydrochloride), which shows potent tumor regression activity against Colon 38 cancer inoculated s.c. Here, we describe studies on the cell-killing activity against a panel of human cancer cell lines and the antitumor activity of ER-37328 against human tumor xenografts. In a cell-killing assay involving 1-h drug treatment, ER-37328 showed more potent cell-killing activity (50% lethal concentrations (LC₅₀s) ranging from 2.9 to 20 μM ) than etoposide (LC₅₀s>60 μM ) against a panel of human cancer cell lines. ER-37328 induced double-stranded DNA cleavage, an indicator of topo II-DNA cleavable complex formation, within 1 h in MX-1 cells, and the extent of cleavage showed a bell-shaped relationship to drug concentration, with the maximum at 2.5 μM . After removal of the drug (2.5 μM ) at 1 h, incubation was continued in drug-free medium, and the amount of cleaved DNA decreased. However, at 10 μM , which is close to the LC₅₀ against MX-1 cells, DNA cleavage was not detected immediately after 1-h treatment, but appeared and increased after drug removal. This result may explain the potent cell-killing activity of ER37328 in the 1-h treatment. In vivo , ER-37328 showed potent tumor regression activity against MX-1 and NS-3 tumors. Moreover, ER-37328 had a different antitumor spectrum from irinotecan or cisplatin against human tumor xenografts. In conclusion, ER-37328 is a promising topo II poison with strong cell killing activity in vitro and tumor regression activity in vivo , and is a candidate for the clinical treatment of malignant solid tumors. (Cancer Sci 2003; 94: 119–124)     

Antitumor activity of a derivative of mitomycin, 7-N-[2-[[2-(γ-l-glutamylamino)ethyl]dithio]ethyl]mitomycin C (KW-2149), against murine and human tumors and a mitomycin C-resistant tumor in vitro and in vivo

Summary The antitumor activity of a mitomycin derivative, 7-N-[2-[[2-(-glutamylamino)ethyl]dithio]ethyl]mitomycin C (KW-2149), was evaluated in murine and human tumor models, including a mitomycin C (MMC)-resistant tumor in vitro and in vivo. KW-2149 showed a profound effect against i.p. inoculated P388 leukemia on both a single and an intermittent administration schedule. Against s.c. implanted colon adenocarcinoma 38 (colon 38), KW-2149 was as effective as MMC in ILS% and in tumor growth inhibition on a single-administration schedule. Both compounds were similarly effective when an intermittent schedule was used. KW-2149 showed activity against human tumor xenografts and was effective in two of four non-small-cell lung carcinomas but was not effective against three gastric adenocarcinomas on the singleadministration regimen. The activity of KW-2149 against gastric adenocarcinoma was inferior to that of MMC on a single-administration schedule. However, the antitumor activity of KW-2149 was higher on an intermittent schedule than on a single-administration regimen. The antitumor activity of KW-2149 against human tumor xenografts was similar to that of MMC on an intermittent schedule, and the former drug was effective against both gastric adenocarcinomas and both non-small-cell lung carcinomas. KW-2149 was more effective than MMC against a subline of P388 leukemia that is resistant to MMC in vitro as well as in vivo.     

In vivo and in vitro evaluation of the alkylating agent carmethizole

Carmethizole, a novel bis-carbamate alkylating agent, was evaluated in vitro for potential mechanisms of interaction with DNA and in vivo for spectrum and degree of antitumor activity. In vitro, the concentration of carmethizole required to produce a 50% reduction in clonogenic cell survival was identical in O6-alkylguanine DNA alkyltransferase-positive and -negative human cell lines. The CHO cell line UV4, hypersensitive to mono- and bifunctional alkylating agents, was 37-fold more sensitive to carmethizole than normal cells. The UV5 cell line, which is not hypersensitive to cross-linkers, was 13-fold more sensitive to carmethizole than normal cells. Alkaline elution studies in L1210 cells exposed to carmethizole showed the presence of DNA-protein and DNA-DNA cross-links but not DNA strand breaks. These data suggested that the interaction of carmethizole with DNA produces monoadducts, DNA-protein, and DNA-DNA interstrand cross-links at several sites. In vivo, carmethizole was not cross-resistant with 1,3-bis(2-chloroethyl)-1-nitrosourea or Cytoxan as determined by testing against P388 leukemias resistant to the latter 2 agents. Carmethizole activity was similar to that of melphalan across the murine solid tumor panel, which consisted of B16 melanoma; colon adenocarcinomas 11a, 26, and 36; and the KHT sarcoma. Carmethizole, Cytoxan, and melphalan were all active and had comparable activity against the HCT-8 and MX-1 human tumor xenografts. The in vivo spectrum of activity and efficacy of carmethizole was similar to that of melphalan.     

KF25706, a novel oxime derivative of radicicol, exhibits in vivo antitumor activity via selective depletion of Hsp90 binding signaling molecules.

Radicicol, a macrocyclic antifungal antibiotic, has been shown to bind to the heat shock protein 90 (Hsp90) chaperone, interfering with its function. Hsp90 family chaperones have been shown to associate with several signaling molecules and play an essential role in signal transduction, which is important for tumor cell growth. Because radicicol lacks antitumor activity in vivo in experimental animal models, we examined the antitumor activity of a novel radicicol oxime derivative, radicicol 6-oxime (KF25706), on human tumor cell growth both in vitro and in vivo. KF25706 showed potent antiproliferative activities against various human tumor cell lines in vitro and inhibited v-src- and K-ras-activated signaling as well as radicicol. In addition, Hsp90 family chaperone-associated proteins, such as p185erbB2, Raf-1, cyclin-dependent kinase 4, and mutant p53, were depleted by KF25706 at a dose comparable to that required for antiproliferative activity. KF25706 was also shown to compete with geldanamycin for binding to Hsp90. KF29163, which is an inactive derivative of radicicol, was less potent both in p185erbB2 depletion and Hsp90 binding. More importantly, KF25706 showed significant growth-inhibitory activity against human breast carcinoma MX-1 cells transplanted into nude mice at a dose of 100 mg/kg twice daily for five consecutive i.v. injections. KF25706 was also shown to possess antitumor activity against human breast carcinoma MCF-7, colon carcinoma DLD-1, and vulval carcinoma A431 cell lines in vivo in an animal model. Finally, we confirmed the depletion of Hsp90-associated signaling molecules (Raf-1 and cyclin-dependent kinase 4) with ex vivo Western blotting analysis using MX-1 xenografts. In agreement with in vivo antitumor activity, KF25706 depleted Hsp90-associated molecules in vivo, whereas KF29163 and radicicol did not show this activity in vivo. Taken together, these results suggest that antitumor activity of KF25706 may be mediated, at least in part, by binding to Hsp90 family proteins and destabilization of Hsp90-associated signaling molecules.     

A new analogue of 10-deazaaminopterin with markedly enhanced curative effects against human tumor xenografts in mice

Purpose: These studies sought to evaluate the biochemical and cellular pharmacokinetic properties, cytotoxicity and antitumor efficacy of a new analogue of 10-deaza-aminopterin (PDX) against human tumors. Methods: Studies were conducted with a group of human tumor cell lines in culture examining PDX and other folate analogues as permeants for mediated membrane transport, as inhibitors of dihdrofolate reductase and as substrates for folylpolyglutamate synthetase. These same analogues were examined for their cytotoxicity following a 3-h pulse exposure, in experiments providing a value for IC₅₀. Other studies with these analogues were conducted in nude mice bearing subcutaneously implanted human tumors. Treatment of the mice was initiated 4 days after implantation of the tumor using a schedule of administration of one dose per day for 5 days. The tumors were measured 6 days after cessation of therapy and compared to controls for assessment of response. Results: In the CCRF-CEM cell system, PDX was 2- to 3-fold less effective as an inhibitor of dihydrofolate reductase than aminopterin (AMT), methotrexate (MTX) or edatrexate (EDX) but much more effective as a permeant for one-carbon, reduced folate transport inward (PDX >AMT ≃ EDX >MTX) and substrate for folylpolyglutamate synthetase (PDX >AMT >EDX >MTX). As predicted by these results, PDX was 15- to 40-fold more cytotoxic than MTX and 3- to 4-fold more cytotoxic than the highly potent EDX following a 3-h pulse exposure in culture of CCRF-CEM cells and cells from a panel of three human breast and two human nonsmall-cell (NSC) lung cancers. The same relative differences were shown for the therapeutic efficacy of these three analogues at equitoxic doses in studies with the human MX-1 and LX-1 tumors and the human A549 NSC lung tumor xenografted in nude mice. On a schedule of qd × 5 given 3–4 days posttransplant, MTX was minimally active (modest tumor growth delay) against all three tumors. EDX was highly active (25–35% complete regressions and 5–10% cures) against the MX-1 and LX-1 tumors but very modestly active (no regressions) against the A549 tumor. In contrast, PDX was even more active (75–85% complete regressions and 25–30% cures) than EDX against the MX-1 and LX-1 tumors and highly active (30% complete regressions and 20% cures) against the A549 tumor. Conclusions: These studies showed significantly enhanced antitumor properties of PDX compared with MTX and EDX. Based upon these results, clinical trials of PDX in patients with metastatic breast and NSC lung cancer appear to be warranted. Received: 24 September 1997 / Accepted: 16 December 1997     

Antitumor activity of cis-malonato[(4R,5R)-4,5-bis(aminomethy1)-2-isopropyl-1,3-dioxolanelplatinum(II), a new platinum analogue,as an anticancer agent

 The in vitro and in vivo antitumor activity of a new antitumor platinum complex, cis-malonato[(4R, 5R)-4, 5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]platinum(II) (SKI 2053R, NSC D644591), were evaluated and compared with those of cisplatin (CDDP) and carboplatin (CBDCA) using murine tumors. SKI 2053R was highly active in vitro against both L1210 murine leukemia and its CDDP-resistant subline, L1210/DDP; the relative resistances were 20.0-, 14.5-, and 2.7-fold for CDDP, CBDCA, and SKI 2053R, respectively. SKI 2053R showed activity comparable with or superior to either CDDP or CBDCA in mice implanted with L1210. In mice implanted with L1210/DDP, as compared with CBDCA, SKI 2053R showed high values for the percentage of treated survivors relative to controls and for numbers of cured mice, whereas CDDP had virtually no activity. In mice implanted with P388, all three drugs were highly active, but the intensity of activity was shown to be ranked in the following order: SKI 2053R > CDDP > CBDCA. The antitumor activity of SKI 2053R against Lewis lung carcinoma was comparable with that of both CDDP and CBDCA. The antitumor activity of SKI 2053R was further investigated against two human tumor xenografts, KATO III (stomach adenocarcinoma) and WiDr (colon adenocarcinoma), implanted s.c. in nude mice and was compared with that of CDDP. In SKI 2053R-treated groups, the time required for a mean tumor weight of 1,000 mg was 33.1 days in KATO III xenografts and 35.0 days in WiDr xenografts as compared with 30.2 and 27.2 days in CDDP-treated groups, respectively. SKI 2053R achieved growth-inhibition rates comparable with those of CDDP against KATO III (65% versus 59%) and WiDr xenografts (64% versus 54%) on day 35. These results indicate that SKI 2053R is an attractive candidate for further development as a clinically useful anticancer drug. Received: 7 June 1994 / Accepted: 27 September 1994     

Antitumor activity of Virulizin,a novel biological response modifier (BRM) in a panel of human pancreatic cancer and melanoma xenografts

PURPOSE: To define the anticancer efficacy of Virulizin in vivo as a single agent or in combination with conventional drugs in human pancreatic tumor and melanoma xenografts. METHODS: The therapeutic effect of Virulizin was evaluated in a series of human tumor xenografts in athymic nude mice. RESULTS: Virulizin had a high level of antitumor activity against all the pancreatic tumors (BxPC-3, SU 86.86. and Mia-PaCa-2) and melanomas (C8161 and A2058), as indicated by suppression of tumor growth with an optimal T/C value of 相似文献   

Potent reversal of multidrug resistance by ningalins and its use in drug combinations against human colon carcinoma xenograft in nude mice

Purpose: To evaluate the pharmacological properties and the possible therapeutic applications of a series of synthetic marine natural product analogs, ningalins (N1–N6), in terms of cytotoxicity, MDR-reversing activity, and enhancement of drug combinations with antitumor agents in vitro and in vivo. Methods: XTT assays, [³H]azidopine binding to P-glycoprotein (Pgp), cellular accumulation and efflux of labeled drugs were carried out in vitro. Drug combinations using combination index, dose-reduction index, and isobologram were performed in vitro and enhancement of efficacy in drug combinations against human colon carcinoma HCT-116 xenografts were conducted with nude mice. Results: N3 at sub-IC₅₀ cytotoxic concentration (10 M) was capable of enhancing vinblastine (VBL) cytotoxicity toward human leukemic CCRF-CEM cells about 50,000-fold as measured by the decrease of IC₅₀ of VBL. For CCRF-CEM/VBL₁₀₀₀ (1,500-fold resistant to VBL and overexpressing Pgp), N3 and N5 enhanced VBL cytotoxicity as much as 6.2 million-fold and 210,000-fold, respectively. Moreover, N3 and N5 collaterally made CCRF-CEM/VBL₁₀₀₀ cells 4,000-fold and 130-fold, respectively, more susceptible to VBL than the parent CCRF-CEM cells. In human mammary carcinoma cells MX-1/paclitaxel which were 170-fold resistant to taxol and 38-fold resistant to VBL, N3 was capable of enhancing VBL effect as much as 6,000-fold. Combination therapy on murine P388/doxorubicin (DX) leukemia with DX + N3 or taxol + N3 achieved greater efficacy than the therapy with each drug alone. Impressively, nude mice, bearing human colon carcinoma HCT-116 cells, treated with a suboptimal dosage of taxol in combination with N3, N5 or N6 led to shrinkage of established tumor and achieved total tumor remission, while taxol alone had no tumor disappearance in this xenograft model. Furthermore, the enhancement of antitumor effect by ningalins, at least in parts, are due to inhibiting Pgp which was supported by the observation that the ningalins compete for [³H]azidopine binding to Pgp, increase the cellular accumulation of VBL or taxol, and inhibit drug efflux from the tumor cells. Conclusion: The profound enhancement of antitumor cytotoxicity of vinblastine and taxol in vitro by ningalins may have multiple mechanisms including the MDR-reversing effects. The mechanisms for collateral sensitivity by ningalins against sensitive (parent) cells are not yet clear. The marked enhancement of therapeutic effect of taxol by ningalins against xenograft tumors in nude mice suggests potential applications of therapeutic use of ningalins.