Synthesis and antitumor activity of LY288601, the 5,6-dihydro analog of LY231514.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
G B Grindey
Publications and source records attributed to G B Grindey.
Evaluation of new anticancer agents against the MIA PaCa-2 and PANC-1 human pancreatic carcinoma xenografts.
Human pancreatic carcinoma xenograft models were developed from established MIA PaCa-2 and PANC-1 cell lines (ATCC, Rockville, MD). Tumors were maintained by serial trocar implantation in CD1 nu/nu mice, and attempts were made to test all drugs under optimal schedules at maximum tolerated doses. In both models, adriamycin, cisplatin, and 5-fluorouracil were inactive (< 60% inhibition of tumor weight), whereas gemcitabine (LY188011] produced modest activity (69% inhibition in MIA PaCa-2 and 76% inhibition in PANC-1. Major differences in tumor sensitivity were noted with diarylsulfonylureas (DSU) and taxol. The DSU (Sulofenur [LY186641] and LY295501) produced complete inhibition in the MIA PaCa-2 xenograft, but were inactive in PANC-1. Conversely, taxol produced 80% inhibition of PANC-1 tumor growth, but was inactive against MIA PaCa-2. In general, in vivo antitumor activity roughly correlated with in vitro tumor cytotoxicity with the exception of DSU. We have previously shown that DSU are extensively bound to albumin and that in vitro cytotoxic activity in serum-containing medium is not predictive of in vivo antitumor activity. The MIA PaCa-2 and PANC-1 xenograft models may be useful for selecting potential candidates for therapy of human pancreatic cancer.
Animals↗
Antitumor activity and clinical pharmacology of sulofenur in ovarian cancer.
BACKGROUND: Sulofenur is a diarylsulfonylurea with demonstrated antitumor activity in patients with advanced epithelial ovarian cancer refractory to standard chemotherapy. The dose-limiting toxic effects observed in phase I clinical trials have been anemia and methemoglobinemia, resulting in cyanosis. PURPOSE: The purposes of this study were to further define the response rate, toxic effects, and pharmacokinetics and pharmacodynamics of sulofenur in patients with advanced ovarian cancer. METHODS: We conducted a phase II trial of sulofenur at a dose of 800 mg/m2 per day in 35 patients with stage III or IV ovarian cancer refractory to standard chemotherapy. Pharmacokinetics and pharmacodynamics were analyzed by comparing sulofenur parent and metabolite plasma levels with methemoglobin levels. RESULTS: Partial responses lasting 6.5-18 weeks occurred in four (15%; 95% confidence interval = 4%-35%) of the 26 patients assessable for response. In addition, 42% (11) of the assessable patients had prolonged stable disease (median, 20 weeks). The first nine patients received sulofenur as a daily oral dose for 14 days, with a 21-day treatment cycle. However, they developed substantial anemia and methemoglobinemia. As a result, the next 26 patients received sulofenur daily for 5 days followed by 2 days of rest for 3 consecutive weeks, with a 28-day treatment cycle (5/2-day schedule). Preclinical models predicted that 2 days of rest would decrease toxicity while maintaining antitumor activity. Patients treated with the 5/2-day schedule had relatively less severe anemia and methemoglobinemia and needed fewer red blood cell transfusions (31% versus 78% of patients), but 31% still required dose reductions because of these toxic effects. The hydroxy and keto metabolites of sulofenur had prolonged plasma half-lives relative to the parent compound, and the difference was statistically significant. In addition, the correlations of metabolite concentrations with methemoglobin levels were higher than the correlation of sulofenur concentrations with methemoglobin levels, and those differences were statistically significant. CONCLUSION: We conclude that sulofenur has modest clinical activity in heavily pretreated patients with ovarian cancer. IMPLICATIONS: The toxic effects of anemia and methemoglobinemia may limit the ultimate clinical utility of diarylsulfonylureas until less toxic derivatives with alternate metabolic pathways can be identified.
Adult↗
A dideazatetrahydrofolate analogue lacking a chiral center at C-6, N-[4-[2-(2-amino-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidin-5- yl)ethyl]benzoyl]-L-glutamic acid, is an inhibitor of thymidylate synthase.
N-[4-[2-(2-Amino-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidin-5- yl)ethyl]benzoyl]-L-glutamic acid (15), prepared in five steps from 2-pivaloyl-7-deazaguanine, has been found to be an antitumor agent with its primary site of action at thymidylate synthase rather than purine synthesis. This compound appears to be a promising candidate for clinical evaluation.
Animals↗
Sulfonylureas: a new class of cancer chemotherapeutic agents.
This study summarizes the antitumor properties of a number of sulofenur thiophene analogs against subcutaneously implanted 6C3HED lymphosarcoma with structural modification of the aryl moiety of the sulfonamide portion of the diarylsulfonylureas. The spectrum of activity of N-(p-chlorophenyl)-N'- [(5-methoxy-2-thienyl)sulfonyl]urea in the HXGC3, VRC5, CX-1, and LX-1 cell lines is also presented.
Animals↗
Synthesis and biological activity of acyclic analogues of 5,10-dideaza-5,6,7,8-tetrahydrofolic acid.
The synthesis and biological evaluation of a number of analogues of N-[4-[4-(2,4-diamino-1,6-dihydro-6-oxo-5-pyrimidyl) butyl]benzoyl]-L-glutamic acid (2) (7-DM-DDATHF), an acyclic modification of the novel folate antimetabolite 5,10-dideazatetrahydrofolic acid (DDATHF), are described. The synthetic procedure utilized previously for the synthesis of 2, 15, and 16 was extended to the preparation of analogues modified in the benzoyl region with thiophene and methylene groups replacing the benzene ring (compounds 27a-c) and in the glutamate region with aspartic acid and phenylalanine replacing L-glutamic acid (compounds 36, 37). The 2-amino-4,6-dioxo derivative 33 was obtained from intermediate 30 via a palladium-catalyzed carbon-carbon coupling reaction with diethyl (4-iodobenzoyl)-L-glutamate, followed by reduction and removal of protecting groups with base. Cell culture cytotoxicity studies of all of the above acyclic analogues of DDATHF against CCRF-CEM human lymphoblastic leukemic cells gave IC50s ranging from 0.042 greater than 48 microM. Inhibition and cell culture reversal studies against isolated enzymes suggest the mode of action of these compounds. Compound 2 was only 3-fold less inhibitory toward glycinamide ribonucleotide formyltransferase (GARFT, isolated from L1210 leukemic cells) than DDATHF itself. These acyclic analogues were less efficient substrates for the enzyme folylpolyglutamate synthetase (FPGS) compared with their bicyclic counterparts. Moderate antitumor activity was observed for compound 2 against 6C3HED lymphosarcoma and C3H mammary adenocarcinoma in vivo.
Adenocarcinoma↗
Cellular elimination of 2',2'-difluorodeoxycytidine 5'-triphosphate: a mechanism of self-potentiation.
2',2'-Difluorodeoxycytidine (dFdC, Gemcitabine) is a deoxycytidine analogue which, after phosphorylation to the 5'-di- and 5'-triphosphate (dFdCTP), induces inhibition of DNA synthesis and cell death. We examined the values for elimination kinetics of cellular dFdCTP and found they were dependent on cellular concentration after incubation of CCRF-CEM cells with dFdC and washing into drug-free medium. When the drug was washed out at low cellular dFdCTP levels (less than 50 microM), dFdCTP elimination was linear (t1/2 = 3.3 h), but it became biphasic at intracellular dFdCTP levels greater than 100 microM. Although the initial elimination rate was similar at all concentrations, at higher concentrations the terminal elimination rate increased with increasing cellular dFdCTP concentration, with a nearly complete inhibition of dFdCTP elimination at 300 microM. The deamination product 2',2'-difluorodeoxyuridine was the predominant extracellular catabolite at low cellular dFdCTP concentrations, whereas at high dFdCTP concentrations dFdC was the major excretion product. The dCMP deaminase inhibitor 3,4,5,6-tetrahydrodeoxyuridine transformed the monophasic dFdCTP degradation seen at low dFdCTP levels into a biphasic process, whereas the deoxycytidine deaminase inhibitor 3,4,5,6-tetrahydrouridine had no effect on dFdCTP elimination. An in situ assay indicated that dCMP deaminase activity was inhibited in whole cells, an action that was associated with a decreased dCTP:dTTP value. In addition, dFdCTP inhibited partially purified dCMP deaminase with a 50% inhibitory concentration of 0.46 mM. We conclude that dFdC-induced inhibition of dCMP deaminase resulted in a decrease of dFdCTP catabolism, contributing to the concentration-dependent elimination kinetics. This action constitutes a self-potentiation of dFdC activity.
Antimetabolites, Antineoplastic↗
Activity of 2',2'-difluorodeoxycytidine (Gemcitabine) against human tumor colony forming units.
2',2'-Difluorodeoxycytidine (LY 188011, Gemcitabine) is a novel pyrimidine antimetabolite with promising activity in preclinical models for leukemia and solid tumors. Phase I clinical trials with the agent are ongoing. In order to better define types of tumors with clinical sensitivity to Gemcitabine (to help target phase II trials), we have studied the antitumor effects of this agent against a variety of freshly explanted human tumor specimens using an in vitro capillary soft agar cloning system. Final concentrations of 2.0-200 micrograms/ml were used for short-term (1 h) and continuous incubations experiments. Using a short-term incubation, 94/215 (44%) tumor specimens were evaluable for the determination of antitumor activity. The most common tumor types studied included colorectal, breast, non-small cell lung, ovarian cancer, kidney and melanoma. A concentration-dependent increase in the frequency of inhibited tumor specimens was noted (2 micrograms/ml: 6/94 specimens, 20 micrograms/ml: 13/94 specimens, 200 micrograms/ml:33/94 specimens; p less than 0.0001). A similar increase in tumor growth inhibition was found using a continuous incubation (2 micrograms/ml: 0/14 specimens, 20 micrograms/ml: 1/14 specimens, 200 micrograms/ml: 7/14 specimens; p less than 0.001). We conclude that Gemcitabine is an active antitumor agent against tumor colony forming units from a variety of human malignancies if sufficiently high concentrations can be achieved. The agent should be evaluated for Phase II clinical activity against those tumor types.
Antimetabolites, Antineoplastic↗
Effect of 2',2'-difluorodeoxycytidine on the viability and radiosensitivity of EMT6 cells in vitro.
EMT6 mouse mammary tumor cells were used to examine the cytotoxic effects of 2',2'-difluorodeoxycytidine (gemcitabine; dFdC) alone and in combination with radiation. The cytotoxicity of dFdC differed from that of most antimetabolites. The concentration-response curve for exponentially growing cells treated for 4 hr with various drug concentrations was exponential down to a surviving fraction of 0.05; thus, dFdC appeared to kill cells in all phases of the cell cycle, rather than killing only the S-phase cells that compose approximately 50% of the cell population. High concentrations of dFdC were toxic to cells in plateau phase EMT6 cultures, as well as to cells in rapidly proliferating cultures. These findings are thought to reflect the unusual cellular pharmacokinetics of the compound. Treatment of exponentially growing cultures with dFdC before, during, and after irradiation was extremely effective in killing the cells; the survival curves for cells treated with drug plus radiation were statistically compatible with either additive cytotoxicity or a synergistic effect (i.e., radiosensitization by dFdC). These studies also provided evidence that dFdC released by dying cells could produce delayed cytotoxic effects on cells not treated directly with dFdC. These data provide several bases for expecting beneficial therapeutic effects from antineoplastic regimens combining dFdC plus radiation.
Animals↗
Action of 2',2'-difluorodeoxycytidine on DNA synthesis.
The action of the new deoxycytidine analogue 2',2'-difluorodeoxycytidine (dFdC) on DNA synthesis was investigated in whole cells and in vitro assay systems with purified DNA polymerases. DNA synthesis in human lymphoblastoid CEM cells was inhibited by dFdC in a concentration-dependent manner that could not be reversed by exogenous deoxynucleosides. The analogue was incorporated into cellular DNA; most of the incorporated dFdC 5'-monophosphate (dFdCMP) residues were in internucleotide linkage. In vitro DNA primer extension assays demonstrated that dFdC 5'-triphosphate (dFdCTP) competed with deoxycytidine triphosphate for incorporation into the C sites of the growing DNA strand. The ratios of the apparent Km values for the incorporation of dFdCTP and dCTP into a C site of M13mp19 DNA were 21.8 and 22.9 for DNA polymerases alpha and epsilon, respectively. The apparent Ki values of dFdCTP were 11.2 microM for DNA polymerase alpha and 14.4 microM for polymerase epsilon. After dFdCMP incorporation, the primer was extended by one deoxynucleotide before a major pause in the polymerization process was observed. This was in contrast to the action of arabinosylcytosine 5'-triphosphate, which caused both DNA polymerases alpha and epsilon to pause at the site of incorporation. The 3'----5' exonuclease activity of DNA polymerase epsilon was essentially unable to excise nucleotides from DNA containing dFdCMP at either the 3'-end or at an internal position, whereas arabinosylcytosine monophosphate was removed from the 3'-terminus at 37% the rate for deoxynucleotides. The cytotoxic activity of dFdC was strongly correlated with the amount of dFdCMP incorporated into cellular DNA. Our results demonstrate qualitative and quantitative differences in the molecular actions of dFdC and arabinosylcytosine on DNA metabolism, but are consistent with an important role for such incorporation in the toxicity of dFdC.
Antimetabolites, Antineoplastic↗
Diarylsulfonylureas and radiotherapy. I. In vitro studies with N-(5-indanylsulfonyl)-N'-(4-chlorophenyl)-urea (Sulofenur).
The effects of proliferative state and environmental factors on the cytotoxicity of N-(5-indanylsulfonyl)-N'-(4-chlorophenyl)-urea (Sulofenur) were examined using EMT6 mouse mammary tumor cells in monolayer cultures. The toxicity of Sulofenur was at least as great in quiescent, plateau phase cultures as in exponentially growing cultures. Acute hypoxia during treatment did not alter the efficacy of the drug. The pH of the culture medium was a critical determinant of cytotoxicity; survival decreased progressively as the pH of the culture medium decreased from 7.0 to 6.0. High concentrations of Sulofenur appeared to potentiate the cytotoxic effects of x-rays. The cytotoxicity of Sulofenur to quiescent cells, the enhanced cytotoxicity at acutely lowered pH, and the interactions between the drug and radiation all suggest that Sulofenur and other diarylsulfonylureas warrant further examination as agents for use in combination with radiotherapy for the treatment of solid tumors.
Animals↗
Evaluation of the antitumor activity of gemcitabine (2',2'-difluoro-2'-deoxycytidine).
A new pyrimidine antimetabolite, 2',2'-difluorodeoxycytidine, Gemcitabine (LY188011, dFdCyd) has been synthesized and evaluated in experimental tumor models. dFdCyd is a very potent and specific deoxycytidine analogue. The concentration required for 50% inhibition of growth is 1 ng/ml in the CCRF-CEM human leukemia cell culture assay. Concurrent addition of deoxycytidine to the cell culture system provides about a 1000-fold decrease in biological activity. The inhibition of growth of human leukemia cells in culture led to the in vivo evaluation of this compound as a potential oncolytic agent. Maximal activity in vivo was seen with dFdCyd when administered on an every third day schedule. 1-beta-D-Arabinofuranosylcytosine, administered on a daily for 10-day schedule, was directly compared to dFdCyd in this evaluation. dFdCyd demonstrated good to excellent antitumor activity in eight of the eight murine tumor models evaluated. 1-beta-D-Arabinofuranosylcytosine was substantially less active or had no activity in these same tumor models. This in vivo activity against murine solid tumors supports the conclusion that dFdCyd is an excellent candidate for clinical trials in the treatment of cancer.
Animals↗
Studies on the cellular pharmacology of N-(4-methylphenylsulfonyl)-N'-(4-chlorophenyl)-urea.
The cellular pharmacology of N-(4-methylphenylsulfonyl)-N'-(4-chlorophenyl)-urea (MPCU) has been examined in a cloned line of GC3 human colon adenocarcinoma cells. There was a rapid concentrative accumulation of drug, which could be separated into energy-independent and -dependent phases. Accumulation over 15 sec was linear and temperature dependent, but not energy dependent (azide insensitive). The rate of uptake was a linear function of concentration over a wide range (0.0026 to 5 mM). No saturation kinetics were demonstrated. Steady state was achieved within 10 min, and drug levels associated with GC3/C1 cells exceeded the extracellular concentration by 4- to 6-fold. This second phase "concentrative accumulation" of drug was azide sensitive. When cells were incubated to steady state in the presence of azide, removal of azide (with addition of glucose) resulted in a further uptake of sulfonylurea to a higher steady state. When [3H]MPCU was removed from the medium after achieving steady state, loss of drug from cells was rapid (T1/2 approximately 130 sec), and no tight-binding component was apparent. After achieving steady state, cell-associated drug was lost into drug-containing medium reaching a lower steady state if 10 mM azide (+/- glucose) was added. These data indicate that MPCU may enter cells by a non-saturable energy-independent process (passive diffusion) and bind weakly to some intracellular component or become sequestered to some compartment in an energy-dependent manner.
Adenocarcinoma↗
Evidence for mitochondrial localization of N-(4-methylphenylsulfonyl)-N'-(4-chlorophenyl)urea in human colon adenocarcinoma cells.
N-(4-Methylphenylsulfonyl)-N'-(4-chlorophenyl)urea (MPCU) is a new agent that exhibits high therapeutic activity against human and rodent tumor models. Initial studies indicated that in vitro [3H]MPCU was concentrated 4- to 6-fold in GC3/c1 human colon adenocarcinoma cells in an azide-sensitive manner. In this study the dependence of uptake and concentrative accumulation of MPCU upon temperature, plasma membrane potential, and the electrochemical potential of mitochondria has been examined. Accumulation and efflux of MPCU were temperature dependent. At 3.6 microM MPCU, initial rates of uptake (15 s) were 1.4, 38.0, and 84.2 pmol/min/10(6) cells at 2 degrees C, 23 degrees C, and 37 degrees C, respectively. The rate of uptake and concentrative accumulation within GC3/c1 cells was not altered in high K+ buffer or by 1 mM ouabain, indicating that plasma membrane potential was not significant in these processes. Concentrative accumulation, but not initial uptake, was inhibited by carbonyl cyanide p-trifluoromethoxyphenylhydrazone, 2,4-dinitrophenol, and sodium azide. Glucose partially antagonized the inhibition of these agents which uncouple oxidative phosphorylation. Oligomycin, an inhibitor of mitochondrial ATP synthase, did not inhibit uptake or concentrative accumulation of MPCU. However, oligomycin in the presence of 2-deoxyglucose significantly inhibited concentrative accumulation of MPCU. These results suggested that concentrative accumulation of MPCU was dependent upon the mitochondrial transmembrane gradient rather than ATP, although direct implication of ATP could not be excluded. To examine which component of this gradient was predominant in causing MPCU sequestration, the ionophores valinomycin and nigericin were used. Valinomycin, which collapses the charge gradient across the mitochondrial matrix membrane, caused only slight inhibition of MPCU accumulation, and the effect was similar at 2 or 10 mumol. In contrast, nigericin (which collapses the pH gradient and increases mitochondrial membrane potential) inhibited by approximately 90% concentrative accumulation of MPCU. These data suggested that MPCU was being concentrated in mitochondria and that this was dependent upon the pH gradient across mitochondrial membrane. In cells exposed to MPCU or the analogue N-(5-indanylsulfonyl)-N'-(4-chlorophenyl)urea, enlargement of mitochondria was observed within 24 h and appeared to be the initial morphological change associated with drug treatment. These results implicate mitochondria as a site of sequestration of diarylsulfonylureas and as a potential site of action.
Adenocarcinoma↗
N-(5-indanylsulfonyl)-N'-(4-chlorophenyl)urea, a novel agent equally cytotoxic to nonproliferating human colon adenocarcinoma cells.
Diarylsulfonylureas have been shown to have therapeutic activity against rodent and human tumor models, notably causing regressions in some lines of human colon adenocarcinomas in mice. At present the mechanism of cytotoxicity is unknown, although preliminary data implicate mitochondria as a potential site of action. In this study, the cytotoxicity of the diarylsulfonylurea N-(5-indanylsulfonyl)-N'-(4-chlorophenyl)urea (ISCU) has been examined in GC3/c1 human colon adenocarcinoma cells. At cytotoxic concentrations of ISCU, in the presence of albumin as a drug binding species, there was only slight inhibition of [3H]thymidine and [3H]uridine incorporation at concentrations of ISCU up to 140 micrograms/ml and no inhibition of synthesis of protein as determined by incorporation of L-leucine. In the absence of albumin, incorporation of [3H]thymidine into DNA or [3H]uridine into RNA was inhibited at greater than 70 micrograms/ml and 140 micrograms/ml, respectively. As ISCU is highly bound to serum albumin (greater than 99%), it would appear that inhibition of nucleic acid synthesis occurs only at supralethal concentrations of ISCU. The cytotoxicity of ISCU in proliferating or quiescent cell populations was examined. GC3/c1 cells grown in medium containing 0.5% fetal calf serum (FCS) had a 60% reduction in rate of growth, but were more sensitive than cells exposed for 24 h in 10% FCS-medium (IC50 1.9 and 31 micrograms/ml, respectively). When the albumin concentration was adjusted (240 mg/100 ml) to allow equivalent drug binding, IC50 values were similar. In cultures of GC3/c1 cells growth rate was related to the concentration of FCS. In the absence of serum, growth rate was 2.5 to 3.2% that of exponentially growing control cultures in the presence of 10% FCS. Addition of FCS to quiescent cultures after 1 to 6 days in serum-free conditions resulted in immediate growth of cells. Clonogenic potential was also unchanged for at least 6 days under serum-free conditions. Under these conditions, where albumin concentration was adjusted to be equivalent to medium containing 10% FCS, sensitivity of proliferatively quiescent GC3/c1 cells was similar to that in exponentially growing control cultures in which the population doubling time was approximately 22 h. Further, there was no recovery of clonogenic potential when cells were exposed for 24 h to ISCU and maintained in a quiescent state for up to 4 days prior to serum stimulation. These data suggest that the cytotoxic effects of ISCU are independent of the proliferative state of the cell population.(ABSTRACT TRUNCATED AT 400 WORDS)
Adenocarcinoma↗
Automated measurement of transplantable solid tumors using digital electronic calipers interfaced to a microcomputer.
Data collection for transplantable solid tumors has been automated with electronic digital calipers and a balance which have been coupled through an RS-232 interface to a microcomputer. BASIC programs handle data entry, calculations and data storage. A "PROTOCOL" program accepts keyboard input of sample name, notebook number, submitter and dose along with necessary information on tumor system, and then initial animal weights for treatment groups are sent from balance to computer. Data is stored as an ASCII file on floppy disks, and protocol reports are printed. When the test is to be measured, a "MEASURE" program prompts the user for keyboard entry of toxic deaths in each group. Then the computer requests input of width and length of tumors for each animal. These tumor dimensions are sent to microcomputer by pressing a button on the calipers. When a group is completed, final animal weights are sent from balance to microcomputer. Then tumor weights and percent inhibition as compared to appropriate control groups are calculated, and the data is appended to the file for that test. A hard copy is generated as tumors are measured, and reports including percent inhibition can be printed immediately after a test is measured. The data as an ASCII file is transferred via modem to mainframe computer, where another program transfers the information to a database management program. These automated procedures for tumor measurement save time and lessen the chance for error by eliminating manual recording of solid tumor dimensions and subsequent reentry of this data for calculation.
Animals↗
Cytotoxicity and antitumor activity of 2',2'-difluorodeoxycytidine (Gemcitabine).
Explore the source record for details and available documents.
Animals↗
Current status of cancer drug development: failure or limited success?
Murine leukemia models have been a major part of cancer drug screening strategies over the past 30 years. While these models have reliably identified agents active against human leukemias and lymphomas, they have been considerably less effective in identifying new agents for the treatment of common human solid tumors. This review considers the shortcomings of past approaches to cancer drug development, and describes new screening strategies designed to identify carcinoma-selective drugs.
Animals↗