The olivacine S16020 enhances the antitumor effect of ionizing radiation without increasing radio-induced mucositis.

The combination of a novel topoisomerase II inhibitor, S16020, and ionizing radiation (IR) was investigated with the aim of assessing normal tissue tolerance using a mouse mucosal lip model and antitumor activity in a human carcinoma (HEP2) cell line. No increase of acute mucosal reactions was seen when combining S16020 with IR as compared with IR alone. Using clonogenic cell survival assay, a marked enhancement of HEP2 cell killing was found when S16020 was combined with irradiation. Additional in vivo combination of S16020-IR was able to increase markedly the antitumor efficacy as compared with S16020 or irradiation alone. Interestingly, the radiosensitization effect in vivo was observed at relatively low and nontoxic concentrations of S16020, and no dose-effect relationship was found beyond 30 mg/kg. In conclusion, the combination of IR and S16020 seems promising to enhance antitumor activity without increasing deleterious effect in normal tissues and to provide the basis for a new radio-chemotherapy combination.

Time-schedule dependency of S 16020, a new topoisomerase II inhibitor.

S 16020 is a new olivacine derivative which has been shown to intercalate into DNA and to stabilize the cleavable complex formed by DNA and purified topoisomerase II. The aim of the present study was to estimate the impact of time exposure on the in vitro activity of S 16020. This was done on seven cancer cell lines of human origin (head and neck, kidney, and ovary). Doxorubicin was used as a reference drug. The cytotoxic activity of S 16020 remained stable during at least 3 h. A loss of activity of about 30% was apparent after 6 or 24 h preincubation. This relative loss of activity reached about 50% after 72 h preincubation. Considering all tested cell lines, the average IC50 decrease was 89+/-8% for S 16020 with incubation times between 1 and 72 h. An exposure index (El) was calculated to evaluate the effect of time on the cytotoxic efficacy. The reference time was 1 h exposure. The El values were corrected to take into account the loss of drug activity. For the majority of cell lines EI values were greater than 1 for both drugs, particularly after a 6 h exposure time. This means that, in this case as compared to the shorter exposure (1 h), increasing time has a relative detrimental effect on drug efficacy. For the two cancer cell lines of ovarian origin, El values remained close to 1 for both drugs whatever the total exposure time. This means that, in this case, time and concentration have symmetrical effects on cell survival. The pharmacological information provided by the present study may be useful in designing future clinical trials on this potentially interesting new topoisomerase II inhibitor. As a consequence of these data, 1 and 3 h drug administration schedules are currently tested during phase I trials.

[Effect of S9788, cyclosporin A and verapamil on intracellular accumulation of doxorubicin, daunorubicin and daunorubicinol in primary rat hepatocyte culture]. / Effet du S9788, de la ciclosporine A et du vérapamil sur l'accumulation intracellulaire de la doxorubicine, de la daunorubicine et du daunorubicinol dans des hépatocytes de rat en culture primaire.

The aim of this study was to compare the effect of three MDR modulators, cyclosporine A, S9788 and verapamil on the efflux of two anthracyclines, doxorubicin and daunorubicin and of daunorubicinol, the C-13 alcohol metabolite of daunorubicin. Rat hepatocyte primary cultures were used as a model of P-gp expression. They allow to study MDR at different levels of P-gp expression which increases in parallel with culture time. Furthermore, hepatocytes are able to metabolize drugs and enable determination of the role of P-gp on metabolite efflux. Hepatocytes grown for 4 or 48 hours were incubated for 6 hours in the presence of a combination of each modulator and one of the two anthracyclines (0.5 microM). Modulator concentrations used were 1, 5 and 15 microM when associated with DOX, and 1 and 15 when associated with DNR. In fresh hepatocytes, the three MDR modulators did not induce an increase in intracellular retention of the two anthracyclines compared to controls without MDR modulators. At 48 hours of culture, the three tested drugs increased intracellular accumulation of DOX. However, daunorubicin retention was not modified but that of its metabolite was increased. The activity rank order was cyclosporine A > S9788 > verapamil. Cyclosporine A and S9788 were active in simultaneous as well as in sequential combinations with anthracyclines. Verapamil was only effective when co-incubated with anthracyclines.

Influence of S9788, a new modulator of multidrug resistance, on the cellular accumulation and subcellular distribution of daunorubicin in P-glycoprotein-expressing MCF7 human breast adenocarcinoma cells.

A triazinoaminopiperidine derivative synthesized as a modulator of multidrug resistance, S9788, was investigated in the human breast adenocarcinoma MCF7DXR cell line expressing P-glycoprotein. In addition to being less sensitive to daunorubicin, the resistant cell line showed dramatic alterations in the subcellular distribution of daunorubicin, as observed via fluorescence microscopy and quantified via tritiated daunorubicin nuclear distribution analysis. Compared to verapamil and cyclosporin A at 2 and 5 mumol/liter, S9788 proved to be more potent in restoring the cellular accumulation and the subcellular distribution of daunorubicin in the resistant cells. Significant activity of S9788 was observed at 2 mumol/liter, which is clinically achievable, and S9788 restored the nuclear distribution of the drug to the level observed in the parental sensitive cell line. Consequently, the restoration of the cytotoxicity of daunorubicin by S9788 was nearly complete (> 90%) at 2 mumol/liter, wheras cyclosporin A reached this level of activity at 5 mumol/liter, and verapamil was always less active at both concentrations. These results suggest that the modulation of multidrug resistance by S9788 is not only related to the enhancement of the cellular accumulation but also especially by the restoration of the subcellular distribution of the drugs to their nuclear sites of action.

In vitro activity of S 9788 on a multidrug-resistant leukemic cell line and on normal hematopoietic cells-reversal of multidrug resistance by sera from phase I-treated patients.

The triazinoaminopiperidine derivative S 9788 is a new multidrug-resistance modulator that is currently being evaluated in phase I clinical trials. In this study, the reversal effect of S 9788 in comparison with verapamil was shown in vitro in human T-leukemic CCRF-CEM/VLB cells expressing the multidrug-resistance (MDR) phenotype. S 9788 increased in a dose-dependent manner the cytotoxic activity of doxorubicin or vinblastine, with complete reversal of resistance occurring at 2 microM for a concomitant continuous exposure (96 h) to the cytotoxic drugs. At respective concentrations equivalent to the IC10 value (the concentration inhibiting 10% of cell growth), S 9788 was 44 times more potent than verapamil in CCRF-CEM/VLB cells. S 9788 at 2 microM did not enhance the in vitro toxicity of doxorubicin or vinblastine in the human normal bone-marrow erythroid (BFU-E) and myeloid (CFU-GM) progenitors. The effect of exposure duration and concentrations on the synergistic action of modulator and cytotoxic agent closely depended on the cytotoxic agent studied. Post-incubations with S 9788 alone after a 1-h coadministration with vinblastine and S 9788 dramatically increased the reversal effect (4-41 times) in proportion to both the duration of postincubation and the concentration of S 9788. In contrast, for doxorubicin resistance, post-incubation with S 9788 alone induced a maximal 2-fold increase in the reversal effect that was not proportional to the post-incubation duration. In patients treated with S 9788 as a 30-min intravenous infusion during phase I trials, a good correlation was found between the serum levels of S 9788 and the ability to reverse MDR in CCRF-CEM/VLB cells. The reversal effect was dose-dependent and was effective beginning at a plasma concentration of 0.25 microM. These data form a basis for the design of phase II trials using a combination of a loading dose of S 9788 given before vinblastine or doxorubicin administration followed by a maintenance infusion of S 9788 alone for a period of 2-24 h.

[Tamoxifen increases cytotoxic effects of fotemustine. Experimental results on cell lines of human melanoma]. / Le tamoxifène augmente les effets cytotoxiques de la fotémustine. Résultats expérimentaux sur lignées de mélanomes humains.

Fotemustine (Fote) is a new aminoacid linked chloroethyl nitrosourea which has been shown to be useful in disseminated malignant melanoma. The aim of the present study was to analyze the cytotoxic effects resulting from the combination of antiestrogens and Fote on human melanoma cell lines. The antiestrogens tested were tamoxifen (TMX 5.10(-7) M and 5.10(-6) M) and 40H TMX (5.10(-8) M and 5.10(-7) M). As a preliminary step, a series of nine human melanoma cell lines was screened in order to identify and quantify the presence of estradiol receptors (ER) in these cell lines. This led to selecting an ER positive (+) cell line. The drugs alone or in combination were then tested against CAL 1 ER (+) and CAL 7 ER (-) melanoma cell lines. Different sequences of drug combinations were tested using clinically compatible drug concentrations. For CAL 1 cells there was a growth inhibitory effect induced by the antiestrogens given alone. Overall, the presence of the antiestrogens resulted in higher cytotoxic effects than when cells were exposed to Fote alone. The lowest IC50 Fote values as compared to Fote alone were generated by the sequences with the antiestrogens administered before Fote. Significantly, these associations with antiestrogens enabled the IC50 values of Fote to be reduced up to 80%. Globally TMX and 40H TMX had similar synergistic effects. TMX and 40H TMX had a modest influence on Fote cytotoxic effects against CAL 7 ER (-) cells. These data may be useful for optimal planning of future clinical trials for malignant melanoma using antiestrogens and nitrosoureas.

Multidrug resistance circumvention by a new triazinoaminopiperidine derivative S9788 in vitro: definition of the optimal schedule and comparison with verapamil.

The current work was undertaken to investigate the importance of exposure sequence and duration in achieving the maximum reversal action of S9788 on doxorubicin (DOX) cytotoxicity against cells that exhibit the (MDR) multidrug resistance phenotype: the MCF7/DOX cell line. Accumulation and release of DOX were examined in this cell line. The reversal effect was compared with that obtained with verapamil. S9788 activity was schedule dependent: when comparing incubation with S9788 before or after treatment with DOX, the best reversal factor was obtained in the case of a post-treatment incubation (65.6 +/- 7.7 vs 20.8 +/- 7.0). S9788 was a more potent modulating agent than verapamil, whatever the schedule of exposure of the cells to the reversal agent. The reversal of resistance after short-term DOX exposures was caused not only by prolonged cellular accumulation of DOX, but also by its prolonged retention after transfer of cells to DOX-free medium. A relationship was noted between cellular exposure to DOX and the cytotoxic effect, and so the reversal of resistance induced by S9788 appears to be directly linked to the level of cell exposure to DOX. This work provided a rationale for improving the schedule of administration of S9788 in clinical trials.

[Quantitative cytological study of the activity of a new resistance modulator, S 9788, on human leukemic cells using multiparametric image analysis]. / Etude cytologique quantitative de l'activité d'un nouvel agent modulateur de la résistance, le S 9788, sur des cellules leucémiques humaines par analyse d'image multiparamétrique.

The triazinoaminopiperidine derivative S 9788 is a new multidrug resistance modulator. The modulating activity of S 9788, comparatively to those of verapamil and the combination of S 9788 and verapamil, was demonstrated on the human leukemic T cell line CCRF-CEM resistant (about 6000 fold) to vinblastine using Microculture Tetrazolium Assay. S 9788 at 5 microM, strongly potentialized the cytotoxic activity of vinblastine but the reversion of resistance remained partial. Verapamil and the combination S 9788-verapamil, tested at equimolar concentrations, were respectively 1000 and two times less active than S 9788 alone. The impact of S 9788, verapamil and their combination on the cytological modifications bound to vinblastine resistance of CEM cells was evaluated by multiparametric quantitative cytological analysis (21 nuclear parameters measured) using a SAMBA 2005 cell image processor. Treatments with the different modulators, in absence or in presence of vinblastine, had no significant effects on the morphology of sensitive CEM cells. On vinblastine resistant CEM cells, S 9788 and the combination S 9788-verapamil induced significant cytological modifications. These modifications were characterized by a partial reversion of some parameters (more specifically nuclear texture parameters) to values close to those observed in parental sensitive cells and permitted an automatic classification of these treated resistant cells in cells of "sensitive" type with a percentage superior to 50%. In conclusion, the reversion of resistance induced by S 9788 on CEM cells resistant to vinblastine does not fit only with a biological phenomenon like the efflux of cytotoxic agents but is associated with a set of cellular alterations involved in multidrug resistance.

Modulation of anthracycline accumulation and metabolism in rat hepatocytes in culture by three revertants of multidrug resistance.

The aim of this study was to compare the action of three multidrug resistance (MDR) modulators, cyclosporine A, S 9788, and verapamil, on the efflux of two anthracyclines, doxorubicin and daunorubicin, and of daunorubicinol, the C-13 alcohol metabolite of daunorubicin. Rat-hepatocyte primary cultures have been used as a model of P-glycoprotein (Pgp) expression. This model allows the study of MDR at different levels of Pgp expression, which increases in parallel with the time in culture; furthermore, the hepatocytes are capable of metabolizing drugs, which enables the determination of the role of Pgp on metabolite efflux. All modulators tested were incubated for 6 h at concentrations of 1, 5, and 15 microM with doxorubicin (0.5 microM) and at 1 and 15 microM with daunorubicin (0.5 microM) on hepatocytes grown for 4 and 48 h in culture. Daunorubicinol (0.5 microM) was tested with modulators at 48 h of culture. In fresh hepatocytes, the three MDR modulators did not induce an increase in the intracellular retention of anthracycline as compared with controls (no MDR modulator). At 48 h of culture, the three test drugs increased doxorubicin intracellular accumulation. In contrast, daunorubicin retention was not modified, but that of its metabolites was increased. Within the concentration range tested, cyclosporine was the most potent modulator without dose-dependent activity. The activity rank order was cyclosporine > S 9788 > verapamil. Cyclosporine and S 9788 were as active in coincubation as in preincubation with anthracyclines. Verapamil had no action when incubated before the addition of anthracyclines. Cyclosporine and S 9788 had an effect on the intracellular retention of daunorubicinol used alone whereas verapamil did not. The action of cyclosporine and S 9788 on the retention of daunorubicinol proves that at least a part of the efflux of C-13 alcohol metabolites of anthracyclines is mediated by Pgp. This study shows that S 9788, cyclosporine, and verapamil are MDR modulators in hepatocytes with high-level Pgp expression. This study also demonstrates that hepatocytes are a potent tool for the study of the action of new MDR modulators on cytostatic drugs as well as on their metabolites.

Antitumor activity of the new vinca-alkaloid S 12363 alone or in combination with verapamil on a human multidrug resistant renal carcinoma xenograft.

We have established a model of human renal cell carcinoma, Kgg2, transplanted into athymic nude mice which expressed P-glycoprotein (P-gp) (detected by flow cytometry) and a high level of mRNA transcript of mdr1 gene (Northern blot analysis). We have evaluated the antitumor activity of a new highly potent vinca-alkaloid derivative, S 12363, in comparison with the activity of the reference compound vinblastine (VLB), when used alone or in combination with verapamil (VRP). The influence of the calcium influx blocker verapamil on the activity of the combination of S 12363 with adriamycin (ADR) was also determined. The results showed that S 12363 at a dose of 0.05 mg/kg/day, administered alone by intraperitoneal route daily on days 1 to 5, induced a tumoral regression of 50% during the first days after treatment. This effect was potentialized by simultaneous treatment with verapamil at 20 mg/kg/day for 5 days, leading to a long-term reduction of 70% of tumor growth. Vinblastine at a dose of 0.4 mg/kg/day administered alone or in combination with verapamil, using the same protocol, was less efficient. The association of S 12363 at 0.075 mg/kg/day (on days: 1-5, 11, 21 and 31), adriamycin at 2 mg/kg/day (on days: 11, 21 and 31) and verapamil at 20 mg/kg/day (on days: 0-5, 11, 21 and 31) induced an important reduction of tumor growth of 80% at the end of the experiment. In conclusion, the new vinca-alkaloid derivative S 12363 could present a therapeutic advantage over the reference compound vinblastine in the treatment of renal cell carcinoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Reversal of inherent multidrug-resistance in primary human renal cell carcinoma cell cultures by S 9788.

In a panel of 14 primary cultures of human renal cell carcinomas the reversal of inherent multidrug-resistance by S 9788, a new triazinoaminopiperidine derivative, was analysed. In combination with doxorubicin S 9788 revealed an evident reversal of multidrug resistance in 12 cell cultures. Two cell cultures remained unaffected. An association between reversal and P-glycoprotein (P-170) expression suggests that S 9788 exerts its activity through P-glycoprotein.

Tamoxifen enhances the cytotoxic effects of the nitrosourea fotemustine. Results on human melanoma cell lines.

Fotemustine (Fote) is a new amino acid-linked chloroethyl nitrosourea which has been shown to be useful in disseminated malignant melanoma. The aim of the present study was to analyse the cytotoxic effects resulting from the combination of anti-oestrogens and Fote on human melanoma cell lines. The anti-oestrogens tested were tamoxifen (TMX, 5 x 10(-7) mol/l and 5 x 10(-6) mol/l) and 4OH TMX (5 x 10(-8) mol/l and 5 x 10(-7) mol/l). As a preliminary step, a series of nine human melanoma cell lines was screened in order to identify and quantify the presence of oestradiol receptors (ER) in these cell lines. This led to the selection of an ER-positive (+) cell line. The drugs alone or in combination were then tested against CAL 1 ER (+) and CAL 7 ER (-) melanoma cell lines. Different sequences of drug combinations were tested using clinically compatible drug concentrations. For CAL 1 cells, there was a growth inhibitory effect induced by the anti-oestrogens given alone. Overall, the presence of the anti-oestrogens resulted in higher cytotoxic effects than when cells were exposed to Fote alone. The lowest IC50 Fote values as compared to Fote alone were generated by the sequences in which the anti-oestrogens were administered before Fote. Significantly, these associations with anti-oestrogens enabled the IC50 values of Fote to be reduced by up to 80%. Globally, TMX and 4OH TMX had similar synergistic effects. TMX and 4OH TMX had a modest influence on Fote cytotoxic effects against CAL 7 ER-negative cells. These data may be useful for optimal planning of future clinical trials for malignant melanoma using anti-oestrogens and nitrosoureas.

Evaluation of the time-schedule dependency for the cytotoxic activity of the new vinca alkaloid derivative, S 12363 (vinfosiltine).

S 12363 is a new vinca alkaloid derivative obtained by appending an optically active alpha-aminophosphonate at the C23 position of 04-deacetyl vinblastine. The present study concerns four different human tumour cell lines, which represent the spectrum of vinca alkaloid clinical activity. The influence of time exposure on S 12363 growth inhibition was studied in vitro. Cells were exposed to the drug during the following exposure times: 5, 15, 30 min and 1, 3, 6, 12, 24, 48, 72, 144 h. The concentrations of S 12363 applied were between 1 x 10(-2) and 1 x 10(3) nmol/l. The cytotoxic effects were assessed by using the methyltetrazolium (MTT) semi-automated test. Considering the IC50 values in terms of concentration (C) x time (T), I (C x T)50, it was shown that for an equal growth inhibitory effect (50% of cell death) the increased exposure times required higher cumulative drug exposures. More precisely, only very long exposure (greater than 24 h) resulted in very high I (C x T)50. The drug exposure ratios which correspond to I (C x T)50 values for 144 h divided by the I (C x T)50 values for 0.25 h ranged between 2.8 and 18.3. If T and C had symmetrical effects on the final growth inhibition, the I (C x T)50 ratios should have been equal to one. For all cell lines investigated there were similar dose-response curves following two types of S12363 exposure: a single day exposure or three successive daily exposures, the total C x T values being the same in both experimental situations. The basic pharmacological information provided by the present study may encourage further clinical trials of this potentially interesting new vinca alkaloid.

In vitro and in vivo circumvention of multidrug resistance by Servier 9788, a novel triazinoaminopiperidine derivative.

S 9788 is a novel triazinoaminopiperidine derivative which does not belong to any of the classes of compounds known to reverse multidrug resistance (MDR). S 9788 was far more potent than verapamil (VRP) in reversing resistance to adriamycin (ADR) in the ADR-selected murine leukaemia cell lines P388/ADR-1 and P388/ADR-10, and the human chronic myelogenous leukaemia K562/R. Fold reversion with S 9788 (5 microM) was, respectively, 3.5, 5.4 and 11.3 times greater than that with VRP (5 microM). S 9788 was also a more potent reversant of ADR resistance in the intrinsically resistant human colon adenocarcinoma COLO 320DM (2.3 fold), and of vincristine (VCR) resistance in the human MDR1 gene-transfected squamous lung carcinoma line S1/tMDR1 (5.6 fold). The activity of S 9788 depended on both the MDR cell line and the cytotoxic agent. S 9788 (50-100 mg/kg/d) administered IP once a day on days 1-4 resulted in a dose-dependent increase in the chemotherapeutic effect of VCR (0.25 mg/kg/d) in P388/VCR - bearing mice and ADR (4 mg/kg/d) in P388/ADR - bearing mice. Increases in antitumor activity were (% T/C) of +20-34% in the P388/ADR model and + 50-78% in the P388/VCR model with respect to cytotoxic agent treatment alone. S 9788 appeared to be devoid of toxicity at its effective doses. The mechanism of action of S 9788 is unknown but S 9788 (0.5-10 microM) induced a dose-dependent increase in ADR accumulation in KB-Al cells and compared to verapamil its effect was twice as active and approximately seven times more potent. We conclude that S 9788 is a novel agent capable of reversing MDR in vitro and in vivo, and whose pharmacological profile warrants its selection as a candidate drug for eventual assessment in the clinic.

In vivo evidence of complete circumvention of vincristine resistance by a new triazinoaminopiperidine derivative S 9788 in P388/VCR leukemia model.

S 9788, a new triazinoaminopiperidine derivative, was found to be a potent reversant of vincristine resistance in the in vivo murine leukemic P388/VCR model. In two treatment regimens (Q4D days 1, 5 and 9 and QD days 1-9), S 9788 enhanced the antitumor activity of vincristine in a dose-dependent manner, resulting in a complete circumvention of drug resistance for well-tolerated doses of S 9788. S 9788 was also effective in enhancing therapeutic effects of vincristine in the treatment of sensitive P388-bearing mice. These results strongly suggest that S 9788 may be a potential candidate for circumvention of multidrug resistance (MDR) in clinical practice.

[Cytotoxic effects of the combination of a new nitrosourea, fotemustine, combined with 5-fluorouracil and folinic acid depend on the sequence of their administration]. / Les effets cytotoxiques de la combinaison d'une nouvelle nitrosourée, la fotémustine, avec l'association 5-fluorouracile et acide folinique dépendent de la séquence de leur administration.

The present study was designed to analyse the cytotoxic effects of the combination of fotemustine plus 5-fluorouracil (5-FU) and folinic acid (FA). Two human tumor cell lines were used; one line was derived from colon cancer (WIDR) and the other from a non-small cell lung cancer (CAL 12). Cytotoxic effects were assessed by the MTT semi-automated test in 96-well incubation plates. The effects of various drug combinations were evaluated by the isobologram method. The drug combinations tested included fotemustine concentrations of 20, 30, 40, 50 and 70 micrograms/ml, 5-FU concentrations of 5, 15 and 30 micrograms/ml, and a constant FA concentration of 10(-5) M. A total of 180 different experimental conditions were tested. When cells were exposed to fotemustine before 5-FU the final cytotoxic effects for both cell lines were additive or synergistic in the majority of cases (P less than 0.001). The 5-FU concentration was a determinant factor affecting modification of the effects of the drug combination from antagonism (with low 5-FU concentrations) to synergism (high 5-FU concentrations) (P less than 0.001). Addition of FA (10(-5) M) resulted in a significant shift towards synergistic associations for both cell lines. Administration of 5-FU before fotemustine caused a marked antagonism which 10(-5) M FA was unable to significantly shift towards simple additivity.

Preclinical antitumor activity of a new Vinca alkaloid derivative, S 12363.

S 12363 is a new Vinca alkaloid derivative obtained by appending an optically active alpha-aminophosphonate at the C23 position of O4-deacetyl vinblastine. S 12363 was evaluated for cytotoxic and antitumor activity against a spectrum of murine and human tumors. This compound was, respectively, on average, 72- and 36-fold more cytotoxic than were vincristine and vinblastine, when tested on a panel of 2 murine and 37 human tumor cell lines using the microculture tetrazolium assay. S 12363 exhibited significant antitumor activity against murine transplantable tumors (i.p. and s.c. P388 leukemia, i.p. L1210 leukemia, i.p. and i.v. B16 melanoma, i.p. M5076 sarcoma, and s.c. colon adenocarcinoma 38), while no activity was observed on s.c. Lewis lung carcinoma. S 12363, when administered i.p., showed moderate activity on human NCI-H460 lung and PANC-1 pancreas tumor xenografts in nude mice. However, when it was administered i.v., it exerted a significant activity against human HT-29 colon, NCI-H460 lung, NCI-H125 lung, PANC-1 pancreas, and A-431 vulvar tumor xenografts. S 12363 was also active in vivo against a P388 leukemia subline resistant to vincristine. On the in vivo panel of tumors used in this study, S 12363 was at least as active as reference compounds, while its optimal dosage was 10- to 40-fold lower than that of vinblastine, depending on the models studied. The effects of schedule and route of administration on the antitumor activity of S 12363 were studied in both i.p. inoculated P388 leukemia and B16 melanoma, in which the activity was improved by single and intermittent treatment (Days 1, 8, and 15) and i.p. route. S 12363, which differs only by the configuration of the asymmetric carbon atom of the side chain, was 300-fold less cytotoxic and 1000-fold less potent in vivo than was S 12363. These results suggest that S 12363 could present a therapeutic advantage over its congeners and deserves further pharmacological evaluations.

Characterization of the pharmacological antitumor effects of S 12363, a new vinca alkaloid.

S 12363 is a new highly potent vinca alkaloid derivative characterized by the grafting of an a-aminophosphonate, bioisoster of the valine, at the C23 position of O4-deacetyl vinblastine. Using a cell image processor Samba 200 (System for Analytical Microscopic Biomedical Applications), we have studied the effect of S 12363 on cell proliferation of four mammary (MXT, MCF-7, T47-D and MDA-MB231) and two melanoma (HBL and DRD 3) tumor cell lines, and on cell cycle kinetic parameters on human T47-D and HBL tumor cell lines. S 12363 significantly inhibited the growth of these 6 tumor cell lines in a time- and concentration-dependent manner. Three concentrations were tested for 24, 48, 72 and 96 hours incubation times. The human breast T47-D, MCF-7 and melanoma DRD3 and HBL tumor cells were the most sensitive to S 12363. This compound was effective at all doses tested (0.1, 1 and 10 ng/ml) after at least a 24 hour incubation period. The murine MXT and human MDA-MB231 tumor cells were about 10 fold less sensitive than the other cell lines. S 12363 disturbed the cell cycle of T47-D and HBL cell lines and induced a significant accumulation of cells in the G2 + M phases to the detriment of the G0 + G1 phases. The antitumor activity of S 12363 was confirmed in vivo on 2 disseminated murine tumor models, i.e. P388 leukemia implanted subcutaneously and M5076 reticulum-cell sarcoma inoculated intraperitoneally. S 12363 was at least as active as reference compounds vinblastine or vincristine with active doses 5 to 20 times lower.

Synthesis of Mannich bases of 5-hydroxynapthalene-1,8-carbolactone as potential antifungal or antitumor agents.

Mannich bases of 5-hydroxynaphthalene-1,8-carbolactone 1 were prepared from various secondary amines or bulky primary amines and formaldehyde. They were isolated in almost all cases as hydrochlorides. These derivatives were submitted to in vitro antifungal and cytotoxic assays. The antifungal assays were performed against three strains of yeasts and five strains of human pathogenic fungi. Two of the tested compounds, 2i and 2j, exhibited interesting antifungal activities against Candida albicans and Candida tropicalis. The cytotoxic activity was evaluated towards L 1210 leukemia cells. Almost all of the Mannich bases had shown significant activity against this tumor cell line as values of IC50 less than or equal to 4 micrograms/ml are considered interesting. Only one derivative 2 developed better cytotoxicity than the parent compound 1.

Differential in vitro action of S-12363, a new vinblastine derivative, and of its epimer on microtubule proteins.

The action of two epimers of a new vinblastine derivative that differ in their in vivo antitumor activity and their cytotoxicity was studied in vitro in brain microtubule proteins. These two compounds, called S-12363 and S-12362, could not be distinguished from one another or from other active vinca alkaloids by their ability to prevent microtubule assembly. However, they differed strongly both from one another and from vincristine and vinblastine in their ability to induce the formation of tubulin paracrystals and in the stability of the paracrystals following temperature shifts from 0 degree to 37 degrees C and vice versa. The most potent drug, S-12363, induced considerable tubulin aggregation, which was even more pronounced than that observed in the presence of vincristine. Previous results have shown that S-12363, in contrast to vincristine, induces no neurotoxic effects. This observation is in disagreement with a direct relationship between tubulin aggregation and neurotoxicity.