APPLICATION OF MEDIAN-EFFECT IN QUANTITATIVE ANALYSIS OF ANTITUMOR DRUGS IN VITRO

Chemotherapy is one of the main clinical treatments for malignant tumors. It can bring about long-term remittent effect or even recovery to many sensitive tumors. Nowadays, administration of combined antitumor agents is often adopted to enhance the curative effect without increasing their toxicity while reducing the possibility of tolerance. In chemotherapy, integrated administration of medicines with different functioning mechanisms is preferred so as to bring about its synergistic effect. Wh…     

中效原理在体外抗癌药物定量分析中的应用

 目的　在体外利用中效原理定量分析抗癌药物联合应用过程中的协同、相加或拮抗作用。方法　采用MTT法 ,利用中效原理判断联合用药 (阿糖胞苷 ,长春新碱 )对HL 6 0细胞的效应。结果　两种药物单用及联合应用时随药物剂量增加 ,其效应也随之增加。两药大剂量合用时为拮抗效应 ,小剂量合用时为协同效应。两药合用时给药次序不同不会影响合用效应 ,两药合用时药物浓度比例变化会影响合用效应。结论　两种药物合用时大剂量为拮抗 ,小剂量为协同 ,其效应大小与两种药物浓度比例有关 ,而与给药时间次序无关。     

利用中效原理观察抗癌药物的相互作用

目的 :利用中效原理体外定量分析抗癌药物苦参素、5 氟尿嘧啶联合应用对人肝癌细胞株(HepG2 )的相互作用。方法 :采用MTT法及中效原理判断联合用药的效果。结果 :两种药物单独及联合应用时随着药物剂量增加 ,其效应也增加。当fa =0 4 1时 ,CI =1,两药作用相加 ;fa <0 4 1时 ,CI <1,两药为协同作用 ;fa >0 4 1时 ,CI>1,两药拮抗。两药合用时给药时间先后次序不同 ,合用效应差异无显著意义 ,而合用时药物浓度比例变化能够影响合用效应。结论 :两种药物合用小剂量为协同 ,大剂量是拮抗 ,其效应大小与药物浓度比例有关 ,而与给药时间先后次序无关。     

Low folate conditions may enhance the interaction of trifluorothymidine with antifolates in colon cancer cells

Purpose: Trifluorothymidine (TFT) is a fluoropyrimidine that is part of the novel combination metabolite TAS-102, in which TFT is combined with a potent thymidine phosphorylase inhibitor (TPI). TAS-102 is currently tested as an orally chemotherapeutic agent in different schedules in a phase I study. In its monophosphate form, TFT can inhibit thymidylate synthase (TS) activity after binding to the TS-nucleotide binding site leading to dTTP depletion, and in its triphosphate form TFT is incorporated into DNA, eventually leading to DNA damage. In this in vitro study, we investigated whether TFT could potentiate cytotoxicity of the antifolate-based TS inhibitors AG337 (Nolatrexed), ZD1694 (Raltitrexed) and GW1843; and whether increased TS inhibition or DNA damage would be related to this result. Methods: The drug combinations were studied in colon cancer cell lines either grown at low or high folate conditions. Multiple drug effect analysis was performed after measuring growth inhibition when the drugs were combined (MTT Assay) and expressed as Combination Index (CI), where CI<0.9 indicates synergism, CI=0.9–1.1 indicates additivity and CI>1.1 indicates antagonism. Drug target analysis was performed using the TS in situ inhibition assay and the FADU DNA-damage assay. Cells were exposed to either the drugs alone or in combination to determine the effect on TS activity and DNA damage induction, respectively. Results: Three experimental procedures were used to test the interaction of the drugs: either one of the drugs was kept at a constant concentration (IC₂₅) or two drugs were added in a 1:1 IC₅₀-based molar ratio. The combinations of TFT with one of the antifolates in which one of the drugs was kept at a constant concentration were synergistic for all antifolates in WiDr/F cells, which grow in low folate medium (CI=0.6–0.8), but only additive to antagonistic for the cell lines growing in high folate medium: TFT-AG337: CI=0.9–2.3; TFT-ZD1694: CI=0.9–1.3; TFT-GW1843: CI=0.8–1.7. The procedure in which the two drugs were added in a 1:1 IC₅₀-based molar ratio showed antagonism for all three combinations in all cell lines (CI>2.7). TS inhibition (14.3%) and DNA damage (8%) were more pronounced than expected (P<0.05) when TFT was combined with GW1843 in WiDr/F cells, in contrast to AG337 and ZD1694, which showed inhibiting effects as expected (additive). Conclusions: The combination of TFT with the antifolates AG337, ZD1694 and GW1843 is mainly additive when the drugs are given simultaneously and this is mediated by an additive TS inhibition and DNA damage. The drug interaction may partly be dependent on the folate homeostasis since WiDr/F cells growing at low folate conditions show pronounced synergism in growth inhibition, two-sided TS inhibition and DNA damage, especially when TFT is combined with the tight-binding TS inhibitor GW1843.     

In vitro testing of drug combinations employing nilotinib and alkylating agents with regard to pretransplant conditioning treatment of advanced-phase chronic myeloid leukemia

Purpose

The prognosis of patients with advanced-phase chronic myeloid leukemia (CML) remains dismal despite the availability of targeted therapies and allogeneic stem cell transplantation (allo-SCT). Increasing the antileukemic efficacy of the pretransplant conditioning regimen may be a strategy to increase remission rates and duration. We therefore investigated the antiproliferative effects of nilotinib in combination with drugs that are usually used for conditioning: the alkylating agents mafosfamide, treosulfan, and busulfan.

Methods

Drug combinations were tested in vitro in different imatinib-sensitive and imatinib-resistant BCR–ABL-positive cell lines. A tetrazolium-based MTT assay was used for the assessment and quantification of growth inhibition after exposure to alkylating agents alone or to combinations with nilotinib. Drug interaction was analyzed using the median-effect method of Chou and Talalay, and combination index (CI) values were calculated according to the classic isobologram equation.

Results

Treatment of imatinib-sensitive, BCR–ABL-positive K562 and LAMA84 cells with nilotinib in combination with mafosfamide, treosulfan, or busulfan resulted in synergistic (CI < 1), additive (CI ~ 1), and predominantly antagonistic (CI > 1) effects, respectively. In imatinib-resistant K562-R and LAMA84-R cells, all applied drug combinations were synergistic (CI < 1) at higher growth inhibition levels.

Conclusions

Our in vitro data warrant further investigation and may provide the basis for nilotinib-supplemented conditioning regimens for allo-SCT in advanced-phase CML.     

利用中效原理观察紫杉醇和木黄酮对子宫内膜癌JEC细胞的作用

[目的]利用中效原理体外定量分析紫杉醇及木黄酮对子宫内膜癌JEC细胞的作用。[方法]采用MTT法观察两药单用及合用时对JEC细胞的抑制率,用中效方程计算两药的中效浓度,并计算两药合用时的合用指数（CI）。[结果]两药单独使用时随着药物剂量的增加,其效应也增加,紫杉醇的中效浓度为5.33μmol/L,木黄酮的中效浓度为190.98μmol/L。两药合用时的中效浓度为49.31μmol/L。两药在高效应剂量时合用效应为协同（CI〉1）,在低效应剂量时合用效应为拮抗（CI〈1）。[结论]紫杉醇联合木黄酮对子宫内膜癌JEC细胞有抑制作用,两种药物大剂量合用时效应为协同,小剂量合用时效应为拮抗。     

Sequence-dependent growth-inhibitory effects of the in vitro combination of fluorouracil,cisplatin, and dipyridamole

The present study was designed to analyze the growth-inhibitory effects of the combination of fluorouracil (FUra), cisplatin (CDDP), and dipyridamole (DP). These toxic effects were assessed on the human breast-carcinoma cell line MCF-7 using the MTT (tetrazolium bromide) assay in 96-well culture dishes. Data were analyzed using the median-effect principle. The drug combinations tested included FUra concentrations ranging from 0.8 to 800 nmol/l, CDDP concentrations of 0.3–30 mol/l, and DP concentrations of 2–200 mol/l. A total of 189 different experimental conditions were tested, including different sequences of administration, with being DP applied before, simultaneously with, or after the two antitumor drugs. Synergistic cytotoxic interactions were found between FUra and CDDP, FUra and DP, and CDDP and DP as well as when the three drugs were combined. The sequence of exposure did not influence the growth-inhibitory activity of the combination FUra-CDDP but altered the effect of combinations of either FUra or CDDP with DP, since at lower concentrations the effect shifted from synergism to antagonism when DP was added simultaneously with CDDP and after the two antitumor drugs. However, the interaction was shown to be truly synergistic by median-effect analysis when the two antitumor drugs were simultaneously associated, with no change in the synergistic effect being observed for the three DP administration sequences.Abbreviations FUra fluorouracil - CDDP cisplatin,cis-diamminedichloroplatinum(II) - MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (azolyl blue); IC₅₀, concentration inducing 50% inhibition of cell growth; fa, fraction affected; fu, fraction unaffected - Cl combination index     

Hyperthermia and platinum complexes: Time between treatments and synergy in vitro and in vivo

To investigate the greatest therapeutic efficacy, we investigated the effect of scheduling on the cytotoxic interaction between hyperthermia and seven different platinum complexes in vitro and in vivo using the FSaII murine fibrosarcoma cells. Hyperthermia treatment (43°C, 1 h) was administered at various times relative to exposure of the cells to the IC₉₀ (at 37°C, 1 h) of each platinum complex. Greater-than-additive killing of FSaII cells was obtained with cis-diamminedichloroplatinum (II) (CDDP) and hyperthermia when the drug and heat exposure were overlapping or simultaneous. The same cell killing effect with carboplatin and hyperthermia resulted from heat exposure up to 5 h prior to, simultaneous with, or immediately after the drug exposure. D-Tetraplatin and K₂PtCl₄ were synergistic with hyperthermia only if the drug and heat exposure were simultaneous. PtCl₄(Nile Blue)₂ and hyperthermia produced greater-than-additive cell killing if the heat and drug exposure occurred in immediate sequence, simultaneously, or with drug exposure up to 5 h prior to heat exposure. PtCl₄(Rh-123)₂ and hyperthermia produced greater-than-additive cell killing if the drug and heat occurred in immediate sequence, overlapping, or simultaneously. PtCl₄(Fast Black)₂ and hyperthermia were additive over a wide range of scheduling from heat exposure 2 h prior to 5 h after drug exposure. When animals bearing FSaIIC tumours were treated with single doses of CDDP (10 mg/kg), carboplatin/PtCl₄(Nile Blue)₂ (50 mg/kg), PtCl₄(Rh-123)₂/PtCl₄(Fast Black)₂ (100 mg/kg) under various combined schedules with hyperthermia treatment (43°C, 30 min), similar cytotoxicity patterns were observed. To administer hyperthermia at a time when the drug concentration in the tumour tissue is at peak level, careful scheduling of systemically administered anticancer drugs with hyperthermia is needed. Modelling studies can identify the stringency/flexibility of drug/heat scheduling to achieve synergistic tumour cell killing.     

Interaction between gemcitabine and mitomycin-C in vitro

Both gemcitabine (2′,2′-difluorodeoxycytidine; dFdCyd) and mitomycin-C (MMC) are active against several solid malignancies. dFdCyd is an attractive agent for use in combination with drugs which damage DNA and with radiation therapy because of its ability to inhibit DNA replication and repair as well as its radiosensitizing effect. We hypothesized that the repair of MMC adducts in DNA might be inhibited by dFdCyd leading to a synergistic effect. To test this possibility, we studied the effect of combining dFdCyd and MMC in HT29 human colon carcinoma cells in vitro. The cells were exposed to a variety of drug concentration ratios and schedules, then assessed for clonogenic survival. D₅₀ values (drug concentration at which clonogenicity is inhibited by 50%) were calculated, and the interactive effects of the two drugs were evaluated using median effect analysis. In this approach, if the calculated combination index (CI) is <1, 1, or >1, it indicates synergism, additivity, or antagonism, respectively (Chou and Talalay 1984). We found that marked synergy (CI of 0.5–0.7) was produced by concurrent exposure to mitomycin and gemcitabine. In contrast, sequential treatment led only to additivity. These findings suggest that, when combined in an appropriate schedule, the chemosensitizing effect of gemcitabine may be beneficial in the treatment of malignancies which are sensitive to MMC. Received: 19 November 1998 / Accepted: 21 June 1999     

In vitro schedule-dependent interaction between paclitaxel and oxaliplatin in human cancer cell lines

Purpose In order to define the most effective administration schedule of the combination of paclitaxel and oxaliplatin, we investigated the in vitro interaction between these drugs in a panel of three human cancer cell lines (AZ-521 gastric adenocarcinoma cell line, HST-1 tongue squamous carcinoma cell line, and KSE-1 esophageal squamous carcinoma cell line).Materials and methods Cytotoxic activity was determined by the WST-1 assay. Different administration schedules of the two drugs were compared and evaluated for synergism, additivity, or antagonism with a quantitative method based on the median-effect principle of Chou and Talalay. Cell cycle perturbation and apoptosis were evaluated by flow cytometry.Results Simultaneous treatment of cells with paclitaxel and oxaliplatin showed greater than additive effects. Upon 24-h sequential exposure, the sequence of paclitaxel followed by oxaliplatin showed synergistic effects in AZ-521 and HST-1 cells, and greater than additive effects in KSE-1 cells, while the opposite sequence yielded marked antagonistic effects in all three cell lines. Flow cytometric analysis indicated that paclitaxel induced G₂/M arrest with subsequent induction of apoptosis in the sub-G₁ phase. Apoptosis was most prominent when paclitaxel preceded oxaliplatin, which produced apoptosis in the majority of treated cells (75%). By contrast, the reverse sequence yielded only 39% induction of apoptotic cells, the rate being not different from those induced by each drug singly.Conclusions Our findings suggest that the interaction of paclitaxel and oxaliplatin is highly schedule-dependent and that the sequential administration of paclitaxel followed by oxaliplatin should thus be incorporated into the design of a clinical trial.     

Quantitative combination effects between sulforaphane and 3,3'-diindolylmethane on proliferation of human colon cancer cells in vitro

Isothiocyanates (ITCs) and indoles derived from cruciferous vegetables possess growth-inhibiting and apoptosis-inducing activities in cancer cell lines in vitro. ITCs like sulforaphane (SFN) are cytotoxic, whereas indoles including indole-3-carbinol or its condensation product 3,3'-diindolylmethane (DIM) are acting by cytostatic mechanisms in human colon cancer cell lines. In the present study, we have investigated the impact of defined combinations of SFN and DIM (ratio 1:4, 1:2, 1:1, 2:1 and 4:1) on cell proliferation, cell-cycle progression and apoptosis induction in cultured 40-16 colon carcinoma cells. Calculations of combination effects were based on the method of Chou et al. (1984) Adv. Enzyme Regul., 22, 27-55, and were expressed as a combination index (CI) with CI < 1, CI = 1 or CI > 1 representing synergism, additivity or antagonism, respectively. Interestingly, at a total drug concentration of 2.5 microM, all combinations of SFN and DIM were antagonistic. With increasing concentrations, the antagonistic effect gradually turned into a synergistic interaction at the highest combined cytotoxic concentration of 40 microM. Cell-cycle analyses with SFN:DIM ratios of 1:1, 1:2 and 1:4 and total concentrations between 10 and 25 microM confirmed antagonism at low and additive effects at higher doses. SFN (10 microM) in combination with DIM (10 microM) resulted in strong G(2)/M cell-cycle arrest, which was not observed with either compound alone. Our results indicate that cytotoxic concentrations of SFN:DIM combinations affect cell proliferation synergistically. At low total concentrations (below 20 microM), which are physiologically more relevant, the combined broccoli compounds showed antagonistic interactions in terms of cell growth inhibition. These data stress the need for elucidating mechanistic interactions for better predicting beneficial health effects of bioactive food components.     

Synergistic and additive combinations of several antitumor drugs and other agents with the potent alkylating agent adozelesin

Adozelesin is a highly potent alkylating agent that undergoes binding in the minor groove of double-stranded DNA (ds-DNA) at A-T-rich sequences followed by covalent bonding with N-3 of adenine in preferred sequences. On the basis of its highpotency, broad-spectrum in vivo antitumor activity and its unique mechanism of action, adozelesin has entered clinical trial. We report herein the cytotoxicity for Chinese hamster ovary (CHO) cells of several agents, including antitumor drugs, combined with adozelesin. The additive, synergistic, or antagonistic nature of the combined drug effect was determined for most combinations using the median-effect principle. The results show that in experiments using DNA- and RNA-synthesis inhibitors, prior treatment with the DNA inhibitor aphidicolin did not affect the lethality of adozelesin. Therefore, ongoing DNA synthesis is not needed for adozelesin cytotoxicity. Combination with the RNA inhibitor cordycepin also did not affect adozelesin cytotoxicity. In experiments with alkylating agents, combinations of adozelesin with melphalan or cisplatin were usually additive or slightly synergistic. Adozelesin-tetraplatin combinations were synergistic at several different ratios of the two drugs, and depending on the schedule of exposure to drug. In experiments using methylxanthines, adozelesin combined synergistically with noncytotoxic doses of caffeine or pentoxifylline and resulted in several logs of increase in adozelesin cytotoxicity. In experiments with hypomethylating agents, adozelesin combined synergistically with 5-azacytidine (5-aza-CR) and 5-aza-2-deoxycytidine (5-aza-2-CdR). Combinations of adozelesin with tetraplatin or 5-ara-2-CdR were also tested against B16 melanoma cells in vitro and were found to be additive and synergistic, respectively. The synergistic cytotoxicity to CHO cells of adozelesin combinations with tetraplatin, 5-aza-CR, or pentoxifylline was not due to increased adozelesin uptake or increased alkylation of DNA by adozelesin.     

Comparative study of sequential combinations of paclitaxel and methotrexate on a human bladder cancer cell line

We investigated the cytotoxic effect of different sequential combinations of paclitaxel (Taxol, TX), an antimicrotuble agent, and methotrexate (MTX), a potent inhibitor of dihydrofolate reductase, on a human bladder cancer cell line (T24). The results obtained with a colony-forming assay 5 days after 24 hr of exposure to TX alone showed a strong decline in colony growth up to a concentration of 6 nM. There was a plateau phase at TX concentrations ranging from 6 to 10 nM. The IC50 values found with the different dosing sequences and 24-hr exposure to the drugs were 0.24 microM for MTX alone, 3.49 nM for TX alone, 3.84 nM for TX followed by MTX, 3.75 nM for TX and MTX simultaneously, and 2.10 nM for MTX followed by TX. The cytotoxic effect due to drug interactions in the different sequential combinations was evaluated by an algebraic method. All the combination sequences were found to be synergistic (combination index [CI] < 1) at low TX concentrations. An antagonistic effect (CI > 1) was obtained at higher TX concentrations. Our data demonstrate that the T24 cell line is sensitive to TX and that the cytotoxic effect is enhanced to different degrees depending on the treatment sequence when TX is combined with MTX. These findings could have implications in the design of appropriate administration schedules of these two drugs for the treatment of bladder cancer.     

Drug administration in combination for management of cancer

The use of drugs in combination for the management of cancer patients aims at the increased therapeutic advantage by elimination the problem of the heterogeneous sensitivity of cancer cells to anticancer drugs, and by delaying or preventing the development of drug resistance within given tumors. Theoretically, the effects of drugs in combination are classified as antagonistic, subadditive, additive and synergistic. Since these results hold for both tumors and hosts, the effects of combined drugs should be considered in terms of therapeutic index. From this viewpoint, the choice and administration schedule of drugs in combination must be synergistic or additive for the tumors and antagonistic or subadditive for the hosts in regard to combined effects. Thus, the rationale for combined drug therapy should be considered from the aspects of biochemical basis, drug resistance, cytokinetic and pharmacologic rationales, and toxicologic basis.     

Synergistic activity of the new ABL-specific tyrosine kinase inhibitor STI571 and chemotherapeutic drugs on BCR-ABL-positive chronic myelogenous leukemia cells.

The ABL-specific tyrosine kinase inhibitor STI571 (formerly CGP57148B) induced cytogenetic remissions in 33% of chronic myelogenous leukemia (CML) patients in a phase I trial (Druker et al 1999). Combination therapy may increase this proportion. We tested whether combinations of STI571 and cytarabine or other chemotherapeutic agents such as hydroxyurea, mafosfamide or etoposide would display synergistic activity in BCR-ABL-positive chronic myelogenous leukemia (CML) cell lines derived from patients in blast crisis. In addition, the toxicity of these combinations on BCR-ABL-negative cells was investigated. A tetrazolium-based MTT assay was used to quantity growth inhibition after 48 h of exposure to cytotoxic agents alone and in simultaneous combination with STI571. The drug interactions were analyzed using the median-effect method of Chou and Talalay. The combination index (CI) was calculated according to the classic isobologram equation. At growth inhibition levels of over 50%, STI571 + cytarabine as well as STI571 + etoposide were significantly synergistic (CI < 1, P < 0.05) in the BCR-ABL-positive cell lines evaluated. At 60% inhibition or higher, a similar synergistic pattern became apparent for STI571 + mafosfamide (P < 0.05), while STI571 + hydroxyurea showed ambiguous, cell line-dependent synergism (BV173), additivity (EM-3) or antagonism (K562) in CML cell lines. Furthermore, the BCR-ABL-negative HL-60, KG1a and normal CD34+ progenitor cells were not affected by 0.8 microM STI571, a concentration which produced more than 50% growth inhibition in all BCR-ABL-positive cells tested, and no potentiation of growth inhibition was observed in these BCR-ABL-negative cells when STI571 was combined with chemotherapeutic agents. Our in vitro data with CML blast crisis cell lines strongly suggest that combinations of STI571 with cytarabine or etoposide be rapidly considered for clinical testing.     

In vitro synergistic effects of vinflunine, a novel fluorinated vinca alkaloid, in combination with other anticancer drugs

Purpose: Vinflunine (20′-20′-difluoro-3′,4′-dihydrovinorelbine), a novel derivative of vinorelbine characterized by marked antitumour activity in vivo in a series of experimental murine and human tumours is currently undergoing phase I evaluation. To investigate its potential for inclusion in combination chemotherapy regimens, this preclinical study was undertaken. The in vitro cytotoxicity of vinflunine incubated simultaneously with one of the following drugs was investigated: camptothecin, cisplatin, doxorubicin, etoposide, 5-fluorouracil, gemcitabine, mitomycin C, paclitaxel or vinorelbine. Methods: The combinations were first evaluated in vitro against the A549 human non-small-cell lung cancer cell line using median-effect analyses. Results: The results revealed synergistic cytotoxicity when vinflunine was combined with cisplatin, mitomycin C, doxorubicin or 5-fluorouracil. Synergy was also observed when testing similar combinations against CCRF-CEM human leukaemia cells. Finally, these findings were comparable with those resulting from such combinations involving vinorelbine instead of vinflunine. Conclusion: Vinflunine appears a promising candidate for combining with other anticancer drugs. Received: 6 September 1999 / Accepted: 1 January 2000     

Antimicrobial Activity of Isepamicin (SCH21420, 1-N-HAPA Gentamicin B) Combinations with Cefotaxime,Ceftazidime, Ceftriaxone,Ciprofloxacin, Imipenem,Mezlocillin and Piperacillin Tested Against Gentamicin-Resistant and Susceptible Gram-Negative Bacilli and Enterococci

Summary

Isepamicin, formerly SCH21420 or 1-N-HAPA gentamicin B, is an aminoglycoside that was tested alone or in combination with one of seven broad spectrum drugs against 80 clinical isolates. Half of the strains were gentamicin-resistant but only one isolate (1.396) was resistant to isepamicin. The broadest spectrum comparison drugs tested alone (ciprofloxacin at 3.8% resistance and imipenem at 5.096 resistance) were associated with the lowest synergy rates when combined with isepamicin. The rank order of synergy (complete or partial) was; cefotaxime = ceftazidime = ceftriaxone = mezlocillin = piperacillin (7596 to 8096) > imipenem (66%) > ciprofloxacin (38%). Isepamicin/ampicillin combinations produced synergistic killing of those enterococci not having high-grade resistance to gentamicin or kanamycin. Enterococcus faecium strains were also refractory to isepamicin/ampicillin synergy. Isepamicin appears to be widely useable against gentamicin-resistant gram-negative bacilli cither alone or combined with most commonly used broad spectrum bcta-lactams.     

紫杉醇联合染料木黄酮对人肝癌细胞株SMMC-7721的作用

目的 利用中效原理体外定量分析紫杉醇及染料木黄酮联合应用对人肝癌细胞株SMMC-7721的作用.方法 采用MTT法观察两种药物单用及合用对肝癌细胞株SMMC-7721的抑制率,然后用中效方程计算各自的中效浓度,并计算两种药物合用时的合用指数(CI).结果 两种药物单独使用时随着药物剂量的增加,其效应也增加,紫杉醇的中效浓度为8.912μmol/L,染料木黄酮的中效浓度为163.680 μmol/L.两种药物合用时的中效浓度为58.340μmol/L.大剂量合用(大于中效浓度)时CI＜1,表示协同;小剂量合用(小于中效浓度)时CI＞1,表示拮抗.结论 紫杉醇联合染料木黄酮对人肝癌细胞株SMMC-7721有抑制作用,两种药物大剂量合用时具有协同作用,小剂量合用时则相互拮抗.     

In vitro search for synergy and antagonism: evaluation of docetaxel combinations in breast cancer cell lines

The use of combination chemotherapy is the accepted standard for most human malignancies but little attention has been paid to drug interactions. A combination of drugs may be synergistic, additive, or antagonistic in cytotoxic activity. This study evaluated combinations of agents with docetaxel, one of the most active agents in human breast cancer, using a median effects model to look at synergy or antagonism in vitro as a potential predictor of clinical outcome. Three human breast cancer cell lines, MCF7/wt, MCF7/adr (multiply drug resistant), and BT474 were grown to confluence, plated into 96 well dishes, and incubated with combinations of drugs for 72 h. Cytotoxic effect was measured by the MTT assay. Median effect analysis was used to calculate the combination index (CI) with values less than 1 indicating synergism, 1 additive effects, and greater than 1 antagonism. Potentially useful combinations for clinical study which were identified included docetaxel with vinorelbine, docetaxel with dexrazoxane, docetaxel with cis-retinoic acid, docetaxel with disulfiram and either doxorubicin or epirubicin, and docetaxel with dexrazoxane and epirubicin.     

Combined 4-hydroxy-ifosfamide and vinorelbine treatment in established and primary human breast cell cultures

Background:Vinorelbine and ifosfamide are active drugs againstbreast cancer, but the best treatment schedule has yet to be defined bypreclinical or clinical studies. The antitumor activity of4-hydroxy-ifosfamide (4-OH-IF), the active form of ifosfamide, and vinorelbine(VNB) and their interaction were investigated in two established breast cancercell lines (MCF-7 and BRC-230) and in 10 primary breast cancer cultures. Materials and methods:Cytotoxic activity was evaluated by ahighly efficient clonogenic assay (HECA). The median-effect principle wasapplied to evaluate synergistic and antagonistic interactions and thecorresponding combination index values were calculated. Cell cycleperturbations were analysed by flow cytometry. Results:In MCF-7 and BRC-230 cell lines the sequence VNB for 4hours followed by 4-OH-IF for 24 hours produced an antagonistic effect.Conversely, the inverse sequential scheme, 4-OH-IF VNB providedsynergistic effects on both cell lines. The synergism was associated with astrong block in the G2-M phase. Synergistic activity of 4-OH-IF VNBsequence was confirmed in 7 of 10 primary breast cancercultures. Conclusions:In conclusion, the sequence 4-OH-IF VNBappeared to be the most effective scheme both in established cell lines andin primary breast cancer cultures.