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PubMed1994

Lung cancer.

In SCLC, combination chemotherapy including agents such as etoposide, teniposide, cisplatin, carboplatin, doxorubicin, vincristine and cyclophosphamide continues to be the backbone of therapy. Epipodophyllotoxin derivatives, together with cisplatin or carboplatin are being increasingly used as part of the initial therapy. Complete plus partial responses to combination chemotherapy occur in 80-90% of all patients with a median duration of 9-11 months. Median survival in these studies is at present 11-16 months, depending on the initial tumour stage. At this point, 5-year survival is around 5% and includes a small fraction of patients (1%) initially presenting with extensive disease. The optimum duration of treatment is still uncertain, but the tendency is to shorten the duration of treatment to 6-9 months. The results of intensifying the treatment with the use of hematopoietic growth factors have hitherto been disappointing. The results of several phase II studies stress the importance of dose scheduling of etoposide in SCLC, with continuous treatment of 5 days' duration or more being superior. The therapeutic results for squamous cell carcinoma, adenocarcinoma, large cell carcinoma and mesothelioma are essentially unchanged. The treatment of patients with these types of lung cancer should continue to be considered experimental, since no standard chemotherapy has as yet been developed, neither when given as single modality nor in combination with surgery or radiotherapy.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1995

Antitumor activities of a new indolocarbazole substance, NB-506, and establishment of NB-506-resistant cell lines, SBC-3/NB.

The novel anticancer glucosyl derivative of indolo-carbazole (NB-506), an inhibitor of DNA topoisomerase I, exhibited strong in vitro cytotoxicity against various human cancer cell lines. In order to elucidate its cytotoxic mechanisms, we established nine NB-506-resistant sublines with different resistance ratios from human small cell lung cancer cells (SBC-3/P) by stepwise and brief exposure (24 h) to NB-506. Among them, SBC-3/NB#9 was 454 times more resistant to NB-506 than the parent cell line. The SBC-3/NB#9 cells showed cross-resistance only to topoisomerase I inhibitors, such as 11,7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecia and 7-ethyl-10-hydroxy-camptothecin, and not to other anticancer drugs, such as vincristine, vinblastine, Adriamycin, etoposide, and teniposide. These results indicate that the difference on the effect of topoisomerase I was considered to be related to a resistance mechanism. The topoisomerase I activities of nuclear extracts eluted from SBC-3/NB#9 cells was only one-tenth of the parent cell activity. A Western blotting study indicated that this lower activity was due to a lower amount of DNA topoisomerase I. Furthermore, we found correlations between topoisomerase I activity and sensitivity to NB-506 in sublines with different degrees of resistance. Accumulation of 3H-labeled NB-506 by SBC-3/NB#9 cells was only one-fifth of that by the parent cells, whereas intracellular accumulation of 3H-labeled camptothecin by both cell lines did not differ. The reduction of accumulation was specific to NB-506, and this result may explain why the resistance ratio for NB-506 was higher than those for 11,7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecin and 7-ethyl-10-hydroxy-camptothecin.

Antineoplastic Agents↗

PubMed1995

Favorable prognosis of hyperdiploid common acute lymphoblastic leukemia may be explained by sensitivity to antimetabolites and other drugs: results of an in vitro study.

DNA hyperdiploidy is a favorable prognostic factor in childhood acute lymphoblastic leukemia (ALL). The explanation for this prognostic significance is largely unknown. We have studied whether DNA ploidy was related to cellular resistance to 12 drugs, assessed with the methyl-thiazol-tetrazolium assay, in samples of 74 children with common (CD10+ precursor B-cell) ALL. Sixteen patients had hyperdiploid ALL cells and 58 patients had nonhyperdiploid ALL cells. Hyperdiploid ALL cells were more sensitive to mercaptopurine (median, 9.0-fold; P = .000003), to thioguanine (1.4-fold; P = .023), to cytarabine (1.8-fold; P = .016), and to I-asparaginase (19.5-fold; P = .022) than were nonhyperdiploid ALL cells. In contrast, these two ploidy groups did not differ significantly in resistance to prednisolone, dexamethasone, vincristine, vindesine, daunorubicin, doxorubicin, mitoxantrone, and teniposide. The percentage of S-phase cells was higher (P = .05) in the hyperdiploid ALL samples (median, 8.5%) than in the nonhyperdiploid ALL samples (median, 5.7%). However, the percentage of cells in S-phase was not significantly related to in vitro drug resistance. We conclude that the favorable prognosis associated with DNA hyperdiploidy in childhood common ALL may be explained by a relative sensitivity of hyperdiploid common ALL cells to antimetabolites, especially to mercaptopurine and to I-asparaginase.

Adolescent↗

PubMed1994

Paclitaxel inhibits progression of mitotic cells to G1 phase by interference with spindle formation without affecting other microtubule functions during anaphase and telephase.

Very low concentrations of paclitaxel, a clinically active anticancer agent isolated from the bark of the Pacific yew tree, were found to produce micronuclei in human colon carcinoma cells, suggesting inhibition of mitotic spindle assembly or function. The possibility that paclitaxel acts at the level of the mitotic spindle was investigated by evaluating its ability to inhibit the progression of mitotic cells to G1 phase. Paclitaxel inhibited mitotic progression with a median inhibitory concentration of 4 nM, a concentration equivalent to the median cytotoxic concentration, without arresting cells in mitosis. A direct correlation was shown to exist between the cytotoxic potency and ability to inhibit mitotic progression for analogues of paclitaxel and antimicrotubule agents but not for the topoisomerase II-active agents etoposide and teniposide. After release from the nocodazole block, cells synchronized in mitosis remained sensitive to very low concentrations of paclitaxel for < 30 min, the time required for spindle formation, yet remained sensitive to vinblastine for > 90 min. This result indicates that very low concentrations of paclitaxel inhibit formation of mitotic spindles in cells without affecting function of preformed spindles and without arresting cells in mitosis. Continuous exposure to low nanomolar concentrations of paclitaxel for more than one cell cycle resulted in cells with DNA contents > 4C and as much as 8C. These results support a hypothesis, that, by not being capable of segregating sister chromatids, paclitaxel-treated cells eventually reform nuclear membranes around individual or clusters of chromosomes, revert to G1 phase cells containing 4C DNA, and enter S phase, resulting in cells with as much as 8C DNA content. It is proposed that this is the primary cytotoxic mechanism of paclitaxel.

Anaphase↗

PubMed1994

Chemotherapy in 998 unselected childhood acute lymphoblastic leukemia patients. Results and conclusions of the multicenter trial ALL-BFM 86.

In trial ALL-BFM 86, the largest multicenter trial of the Berlin-Frankfurt-Münster (BFM) study group for childhood acute lymphoblastic leukemia (ALL), treatment response was used as an overriding stratification factor for the first time. In the previous trial ALL-BFM 83, the in vivo response to initial prednisone treatment was evaluated prospectively. A blast cell count of > or = 1,000/microL peripheral blood after a 7-day exposure to prednisone and one intrathecal dose of methotrexate (MTX) identified 10% of the patients as having a significantly worse prognosis. In trial ALL-BFM 86 patients with > or = 1,000/microL blood blasts on day 8 were included in an experimental branch EG. Patients with < 1,000/microL blood blasts on day 8 were stratified by their leukemic cell burden into two branches, Standard Risk Group (SRG) and Risk Group (RG). SRG patients received an eight-drug induction followed by consolidation protocol M (6-mercaptopurine, high-dose [HD] MTX 4 x 5 g/m2) and maintenance. RG patients were treated with an additional eight-drug reinduction element. For EG patients protocol M was replaced by protocol E (prednisone, HD-MTX, HD-cytarabine, ifosfamide, mitoxantrone). All patients received intrathecal MTX therapy; only those of branches RG and EG received cranial irradiation. In branch RG, patients were randomized to receive or not to receive late intensification (prednisone, vindesine, teniposide, ifosfamide, HD-cytarabine) in the 13th month. During the trial reinduction therapy was introduced in branch SRG, because in the follow-up of trial ALL-BFM 83 the randomized low-risk patients receiving reinduction did significantly better. Nine hundred ninety-eight evaluable patients were enrolled, 28.6% in SRG, 61.1% in RG, 10.3% in EG. At a median follow-up of 5.0 (range 3.4 to 6.9) years, the estimated 6-year event-free survival was 72% +/- 2% for the study population, 58% +/- 5% in branch SRG for the first 110 patients without reinduction therapy, 87% +/- 3% for the next 175 patients with reinduction therapy, 75% +/- 2% in branch RG, and 48% +/- 5% in branch EG. Late intensification did not significantly affect treatment outcome of RG patients; however, only 23% of the eligible patients were randomized. Prednisone poor response remained a negative prognostic parameter despite intensified therapy. The results confirmed the benefit of intensive reinduction therapy even for low-risk patients. The strategy of induction, consolidation, and intensive reinduction may offer roughly 75% of unselected childhood ALL patients the chance for an event-free survival.

Adolescent↗

PubMed1993

[Poisons of DNA topoisomerases I and II].

Over the past decade, DNA topoisomerase I and II appeared to be the targets of some antitumor agents: CPT-11 and Topotecan derived from Camptothecin which interact with topoisomerase I; Actinomycin D, Adriamycin and Daunorubicin, Elliptinium Acetate, Mitoxantrone, Etoposide and Teniposide, Amsacrine which interact with topoisomerase II. The multiple functions of these enzymes are important as they play a role during replication, transcription, recombination, repair and chromatine organisation. Particularly, they relax torsional constraints which appear when intertwined DNA strands are separated while replication fork or RNA polymerases are moving. To some extent, topoisomerase I and II are structurally and functionally different. Moreover, topoisomerase I is not indispensable for a living cell whereas topoisomerase II is. Drug-topoisomerase interaction which probably leads to antitumoral effect of the compounds studied in this review is not a trivial inhibition of the enzyme but rather a poisoning due to stabilization of cleavable complexes between the enzyme and DNA. These stabilized complexes are likely to induce apoptosis-like programmed cell death, which is characterised by DNA fragmentation. However, it appears that it is the collision of the replication fork with the drug-stabilized cleavable complex that is responsible for the cytotoxicity of the drug: poisoning of topoisomerases by antitumor agents leads to a new concept of "dynamic toxicity". Although they interact with a common target, topoisomerase II poisons have differential effects on macromolecules syntheses, cell cycle and chromosome fragmentation; a few compounds may produce free radicals. Because of these differential effects in addition to quantitative and qualitative variations of stabilized cleavable complexes, in particular DNA sequences on which topoisomerase II is stabilized, these antitumor agents do not resemble each other. Cellular resistance to topoisomerases poisons results of two principal types of alteration: target and/or drug transport modification. Decreased ability to form the cleavable complex in resistant cells may be the consequence of both decreased amount of topoisomerase or altered enzyme. On the other hand, overexpression of membrane P-glycoprotein, which pumps drugs out of the cell by an energy dependent process provokes a decreased accumulation of these drugs. Cross resistances to other drugs are mainly under control of these two different mechanisms of resistance. A complete knowledge of their individual effects and mechanisms of resistance would allow a better clinical use of topoisomerases poisons, especially when administered in combination chemotherapy.

Antineoplastic Agents↗

PubMedDate not supplied

Molecular targets in oncology: implications of the multidrug resistance gene.

The curative potential of chemotherapy for a number of tumor types has been obscured by the fact that many patients initially have striking remissions but later relapse and die. At the time of relapse many patients manifest resistance to a wide array of structurally unrelated antineoplastic agents, hence the term multidrug resistance (MDR). Other tumor types, such as those arising in the colon, kidneys, liver, and lungs, tend to exhibit poor response to available cytotoxic drugs. The MDR phenomenon includes cross-resistance among the anthracyclines (doxorubicin, daunorubicin), the epipodophyllotoxins (etoposide, teniposide), the vinca alkaloids (vinblastine, vincristine), taxol, and other compounds. In vitro studies in cell culture indicate that this form of resistance is associated with amplification or overexpression of the mdr1 gene. The mdr1 gene codes for the expression of a cell surface protein, P-glycoprotein (P-gp), which acts as an energy-dependent efflux pump that transports drugs associated with MDR out of the cell before cytotoxic effects occur. The protein is expressed in normal human tissues such as the gastrointestinal tract, liver, and kidneys, where it is thought to serve as an excretory pathway for xenobiotic drugs and toxins. Preliminary studies demonstrated the presence of P-gp in tumor samples from patients with acute leukemia, multiple myeloma, lymphomas, and a variety of solid tumors. A number of drugs are able to reverse MDR, including calcium-channel blockers, phenothiazines, quinidine, antimalarial agents, antiestrogenic and other steroids, and cyclosporine. Limited results from clinical trials with small numbers of patients suggest that the addition of verapamil, diltiazem, quinine, trifluoperazine, or cyclosporine to chemotherapeutic regimens has the potential to reverse MDR; however, toxicities limit their clinical usefulness. A number of trials are under way to identify more active and less toxic modulators of MDR.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1993

Cross-resistance to diverse drugs is associated with primary cisplatin resistance in ovarian cancer cell lines.

We have previously obtained, by exposure to near continuous increasing concentrations of cisplatin, a panel of human ovarian cancer cell lines that exhibit a wide range of primary resistance to the drug (9- to > 400-fold). These cells had strikingly increased (4- to 50-fold) levels of glutathione (GSH) as compared with the drug-sensitive cells of origin (A. K. Godwin et al., Proc. Natl. Acad. Sci. USA, 89: 3070-3074, 1992). Utilizing this panel of resistant cell lines, we evaluated cross-resistance to classical alkylating agents, natural product drugs, and irradiation. We observed that cross-resistance to carboplatin paralleled that of cisplatin, culminating in approximately 250-fold resistance. Similarly, melphalan cross-resistance continued to increase to > 400-fold and again paralleled the primary cisplatin resistance. Cell lines with low to very high levels of resistance to cisplatin are 8- to 850-fold resistant to the epipodophyllotoxin derivative etoposide. Cross-resistance is also observed for other natural product drugs, including Adriamycin (approximately 80-fold), mitoxantrone (approximately 440-fold), and taxol (approximately 40-fold). Cross-resistance to irradiation is, however, modest (< 2-fold). The cells with the greatest primary resistance to cisplatin most commonly had the highest cross-resistance to the other drugs examined. The cross-resistance to the natural product category drugs was found not to be mediated by the products of either the multidrug resistance 1 (MDR1) or multidrug resistance-associated protein (MRP) genes based on lack of coordinate increased expression or amplification of these genes as assessed by Northern and Southern blot analyses. Furthermore, verapamil failed to markedly increase drug sensitivity. Although there was no indication that these natural product drug efflux pumps were operative, we observed decreased doxorubicin accumulation in these cell lines cross-resistant to natural products. In addition, alternations in DNA topoisomerase II mRNA levels, which have been observed in a variety of human tumor cell lines selected in vitro for resistance to etoposide or teniposide, were not detected. Only intracellular levels of GSH correlated with cross-resistance to these diverse anticancer agents and partial loss of resistance was associated with a marked decrease in glutathione levels. In the absence of alternative mechanisms, we speculate that the very broad clinically relevant cross-resistance seen in this model system may, at least in part, be the direct result of GSH-mediated drug inactivation or may be due to a combination of GSH conjugation to drug and conjugate efflux mediated by the putative ATP-dependent glutathione S-conjugate export pump.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMedDate not supplied

Treatment of small cell lung cancer: the Copenhagen experience.

The present article is a review of recent treatment protocols for patients with small cell lung cancer (SCCL) treated in Copenhagen from 1985 to 1990. Furthermore, preliminary data on long-term survivors (> 5 years) from 9 treatment protocols since 1973 are reviewed. For 484 patients < or = 70 years old, no survival difference was observed between 2 platinum (cis-platinum or carboplatin) containing regimens, while the survival was better in these two induction regimens compared to an alternating control arm. For patients > 70 years old, Etoposide (VP-16) and Teniposide (VM-26) were compared in a randomized fashion. Both drugs were highly active, and no significant difference in activity was observed. All together 1527 patients have been included in clinical trials in the Copenhagen Lung Cancer Study Group since 1973. The rates of 5- and 10-years survivors were 3.5% and 1.8% respectively. Long-term survival can be achieved in all stages of SCCL.

Aged↗

PubMed1994

Targeting the cytotoxicity of topoisomerase II-directed epipodophyllotoxins to tumor cells in acidic environments.

The epipodophyllotoxins etoposide and teniposide are probably the most important drugs in the treatment of small cell lung cancer. The drugs are used in maximally tolerated doses, and the toxicity of the drugs precludes significant dose increments. The cellular target is the nuclear enzyme topoisomerase II which, in the presence of these drugs, causes an extensive fragmentation of DNA. The cell kill can be antagonized by distinct drug types. We have demonstrated previously that the intercalating drug aclarubicin and the cardioprotecting agent ICRF-187 antagonize the cytotoxicity of etoposide in vitro. We have studied possible ways of using this antagonism as a means of differentially protecting normal tissue. Here we demonstrate that the intercalating agent chloroquine prevents the introduction of topoisomerase II-mediated DNA breaks and thereby antagonizes the cytotoxicity of etoposide. This interaction depends on the extracellular pH. Chloroquine, in contrast to etoposide, is a weak base and therefore does not enter the cell if the extracellular fluid is acidic, as is the case in most solid tumors. We propose that such a pH-dependent drug interaction may be useful in directing topoisomerase II drug effects toward solid tumors. Thus, by lowering the extracellular pH (pHe) from neutral (pHe = 7.4) to acidic (pHe = 6.0), [3H]chloroquine accumulation was decreased 5-fold in a human small cell lung cancer cell line, OC-NYH, and in murine leukemia L1210 cells. In parallel, the antagonism exhibited by chloroquine on etoposide cytotoxicity was pHe dependent. Thus, no protection by chloroquine was observed at pHe = 6.5, whereas at pHe = 7.4, etoposide cytotoxicity was almost completely antagonized with a 460-fold protection or more than eight doublings of the cell population. This exploitation of antagonist extracellular trapping by acidic pH is a novel model for regulation of anticancer drug effects.

Amsacrine↗

PubMed1993

Involvement of human liver cytochrome P450 3A in vinblastine metabolism: drug interactions.

Vinblastine biotransformation was investigated by using a human liver microsomes library. The drug was converted into one major metabolite (M) upon incubation with the microsomes. A large interindividual variation in vinblastine metabolism was observed among the samples tested, with a 4.4 ratio between the lowest and the highest metabolic rates. The biotransformation of vinblastine followed Michaelis-Menten kinetics (Km = 6.82 +/- 0.27 microM and Vmax = 0.64 +/- 0.06 nmol/min/mg protein). The involvement of the cytochrome P450 3A subfamily in vinblastine metabolism was demonstrated by the following body of evidence: (a) the competitive inhibition of vinblastine biotransformation by cytochrome P450 3A specific probes with Ki values of 0.17, 22.5, 14.8, and 35.3 microM for ketoconazole, erythromycin, troleandomycin, and vindesine, respectively; (b) the immunoinhibition of vinblastine metabolism by polyclonal anti-cytochrome P450 3A antibodies; (c) the highly significant correlation between the level of cytochrome P450 3A determined by Western blots and vinblastine metabolism (r = 0.759, P < 0.001); (d) the highly significant correlation between erythromycin N-demethylase activity (mediated by cytochrome P450 3A) and vinblastine metabolism (r = 0.83, P < 0.001); (e) the significant correlation between the CYP3A4 mRNA level and vinblastine metabolism (r = 0.60, P < 0.1). Although vincristine and navelbine (members of the Vinca alkaloid family) also inhibit the metabolism of vinblastine, suggesting the involvement of the cytochrome subfamily in their respective metabolisms, other anticancer drugs currently associated with vinblastine in chemotherapy (etoposide, Adriamycin, lomustine, and teniposide) also interfere with vinblastine biotransformation. These metabolic drug interactions may alter the antitumor activity and/or toxicity of the drug during anticancer chemotherapy.

Adolescent↗

PubMed1993

Therapeutic drug monitoring in cancer management.

Several anticancer drugs display characteristics that make them suitable candidates for therapeutic drug monitoring (TDM), including substantial pharmacokinetic variability and a narrow therapeutic index. However, concentration-effect relationships (pharmacodynamics) of most antineoplastic agents have not been well defined, thus limiting the widespread clinical application of TDM for cancer chemotherapy. Strategic incorporation of pharmacokinetic studies during phase I-III clinical trials should facilitate the identification of concentration-effect relationships and the definition of clinically useful levels of treatment intensity. We review representative clinical studies that have defined pharmacodynamic relationships for methotrexate, teniposide, etoposide, carboplatin, and mercaptopurine. Given that TDM has impacted positively on the clinical use of many drugs belonging to other therapeutic classes, and that pharmacodynamic correlations have been identified in several recent studies of anticancer drugs, we consider implementation of TDM a rational strategy for optimizing the use of selected antineoplastics.

Antineoplastic Agents↗

PubMed1993

Lung cancer.

In small cell lung cancer, combination chemotherapy including agents such etoposide, teniposide, cisplatin, doxorubicin, ifosfamide, vincristine and cyclophosphamide continues to be the cornerstone of therapy. The importance of dose scheduling of etoposide with continuous treatment of 5 days' duration or more is becoming more and more clear. Complete or partial responses secondary to combination chemotherapy occur in 80-90% of all patients with median durations of 9 to 11 months. Median survival in these studies is unchanged, at present 11-16 months depending on the initial tumour stage. The optimum duration of treatment is still uncertain, but generally a period of 6 to 9 months is used. The use of G-CSF with combination chemotherapy leads to reductions in the incidence of fever, duration and severity of grade 4 neutropenia, and in the total number of days of treatment with i.v. antibiotics and days of hospitalization. No differences have been observed in response rates, duration of response or survival. Therapeutic results for epidermoid, cancer, adeno carcinoma, large cell carcinoma and mesothelioma are essentially unchanged. The treatment of patients with these tumours should continue to be considered experimental since no standard chemotherapy has as yet been developed, neither when given as single modality nor in combination with surgery or radiotherapy. Two studies published in 1991 comparing induction chemotherapy before irradiation versus irradiation alone have resulted in improvement of median and 2-year survival, while a third study did not show such an improvement. The fact remains that three-fourths of patients with local disease die within 3 years, and further improvements in both systemic and local treatment are needed.

Adenocarcinoma↗

PubMed1993

Leaching of diethylhexyl phthalate from polyvinyl chloride containers by selected drugs and formulation components.

The extent of leaching of diethylhexyl phthalate (DEHP) from polyvinyl chloride (PVC) bags by several organic solvents and surfactants used as formulation components and by 12 drug products containing these solvents and surfactants was studied. The organic solvents ethanol, polyethylene glycol, and propylene glycol, the surfactants polysorbate 80 and polyoxyethylated castor oil, and the 12 drugs were admixed separately in PVC bags of 5% dextrose injection. At the time of preparation and after 4, 8, and 24 hours at 24 degrees C, the concentration of DEHP in duplicate samples was determined in duplicate by high-performance liquid chromatography. Ethanol, polyethylene glycol, and propylene glycol at concentrations of 25% and the drugs containing these components did not leach DEHP within the study period. Polysorbate 80 1% to 25% leached detectable amounts of DEHP in as little as one hour at the high concentration and within four hours at the lower concentrations; at 24 hours, DEHP concentrations ranged from 36 micrograms/mL for 1% polysorbate 80 to 237 micrograms/mL for 25% polysorbate 80. Similar results were observed for polysorbate 80 plus ethanol and for polyoxyethylated castor oil plus ethanol. Drug products containing surfactants, including cyclosporine, miconazole, and teniposide, and the vehicles used in formulating taxol and taxotere, leached relatively large amounts of DEHP in 24 hours. Smaller amounts were leached by chlordiazepoxide hydrochloride and etoposide. DEHP was leached from PVC containers by a variety of surfactants and drug products containing these surfactants. Drugs that leach DEHP should be prepared in non-PVC containers and administered through non-PVC tubing.

Chemistry, Pharmaceutical↗

PubMed1993

[Pharmacodynamics of anticancer agents].

Studies of anticancer pharmacodynamics were reviewed. Pharmacodynamics deals with the relationship between therapeutic or toxic response and pharmacological measurements. It is suggested that the lack of pharmacodynamic information is currently limiting the application of pharmacokinetic information to cancer therapy. The studies contain pharmacodynamics of hematologic and non-hematologic toxicities, tumor response and cellular pharmacodynamics. It would be desirable to develop pharmacodynamic models using a limited sampling model during phase II trials, when all patients are treated with the same recommended dose, to relate pharmacokinetic parameters to tumor responses. The return knowledge of pharmacodynamics to cancer chemotherapy makes the concept of individualized therapy, adaptive control strategy with feedback (ACF) and targeted systemic exposure strategy (TSES). St. Jude Children's Research Hospital is now performing a randomized prospective trial to evaluate the efficacy and toxicity of conventional dosages versus individualized therapy using TSES with ACF in Acute lymphocytic leukemia pulse therapy with high-dose methotrexate, teniposide, and cytarabine. It would be a good model for the establishment of oncological pharmacology-based optimal administration of anticancer drugs.

Antineoplastic Agents↗

PubMed1993

[Cytotoxic effect of topoisomerase II inhibitors against adriamycin- and etoposide-resistant small cell lung cancer sublines].

Using reverse transcription polymerase chain reaction, we determined mRNA expression of topoisomerase (topo) II alpha and beta in adriamycin- and etoposide-resistant small cell lung cancer sublines, SBC-3/ADM 100 and SBC-3/ETP. The expression of topo II alpha mRNA decreased substantially in SBC-3/ADM 100 and SBC-3/ETP as compared with the parent cell line, SBC-3; 0.71-fold in the former and 0.38-fold in the latter. Similarly, that of topo II beta mRNA decreased to an extent of 0.68-fold in SBC-3/ADM 100 and 0.28-fold in SBC-3/ETP as compared with the parent cell line. SBC-3/ADM 100 and SBC-3/ETP were highly resistant to topo II inhibitors such as daunorubicin, epirubicin, pirarubicin, mitoxantrone, and teniposide. However, SBC-3/ADM 100 showed a less resistance to aclarubicin, and SBC-3/ETP was as sensitive to the drug as was in the parent cell line. The resistance to topo II inhibitors excluding for aclarubicin might be partially explained by the decreased expression of topo II alpha and beta mRNA.

Carcinoma, Small Cell↗

PubMed1993

Use of yeast in the study of anticancer drugs targeting DNA topoisomerases: expression of a functional recombinant human DNA topoisomerase II alpha in yeast.

A plasmid was constructed for the expression of human DNA topoisomerase II alpha in yeast from a galactose-inducible promoter of the yeast GAL1 gene. Expression of a recombinant human enzyme, in which the first 28 of the 1531 codons of human DNA topoisomerase II alpha were replaced by the first five codons of yeast DNA topoisomerase II, was shown to rescue the lethal phenotype of thermal sensitive yeast DNA topoisomerase II mutants at 35 degrees C. Purification of the human enzyme overexpressed in yeast yielded a single polypeptide with an apparent mass of 170 kDa, and the properties of the purified recombinant enzyme were found to be the same as those reported for human DNA topoisomerase II alpha purified from HeLa cells. Studies with the anticancer drug amsacrine indicated that the human enzyme, either inside yeast cells or in its purified form, is a target of the drug; inhibition of the purified enzyme by teniposide (VM-26) and merbarone was also demonstrated. These studies demonstrate that yeast strains expressing human DNA topoisomerase II alpha provide a convenient system for studying drugs targeting the enzyme; unlike mammalian systems, potential complications due to the presence of human DNA topoisomerase II beta can be eliminated in this system. Overexpression of human DNA topoisomerase II alpha in yeast also provides a convenient source of the enzyme for in vitro studies.

Antineoplastic Agents↗

PubMed1993

Autologous bone marrow transplantation after a long first remission for children with recurrent acute lymphoblastic leukemia.

Fifty-one children with acute lymphoblastic leukemia (ALL) in second or subsequent remission after a first remission of at least 24 months underwent purged, autologous bone marrow transplantation (ABMT). Bone marrow was harvested in remission and purged in vitro with monoclonal antibodies specific for leukemia-associated antigens. Ablative chemotherapy included cytarabine, teniposide, and cyclophosphamide followed by total body irradiation. Of the 51 patients treated between November 1980 and June 1991, 5 died of treatment-related complications, 18 relapsed, 1 died of a second tumor at 6.7 years, and 27 remained in continuous complete remission for a median of 39 months (range, 9+ to 124+). Event-free survival (EFS) (+/- SE) at 3 years after ABMT was 53% +/- 7%. Leukemia-free survival (LFS) was 58% +/- 8%. In multivariate analysis, the most significant predictors of EFS were duration of longest pre-ABMT remission and remission duration immediately before ABMT. For LFS, the most significant predictors were cell dose per kilogram of marrow reinfused and duration of longest pre-ABMT remission. We conclude that ABMT for this population is an effective therapy available to the majority of children with relapsed ALL.

Adolescent↗