The podophyllotoxin derivatives VP16-213 and VM26

GTN057, a komaroviquinone derivative, induced myeloma cells' death in vivo and inhibited c-MET tyrosine kinase

OBJECTIVE

Despite the development of newly developed drugs, most multiple myeloma (MM) patients with high-risk cytogenetic abnormalities such as t(4;14) or del17p relapse at anin early stage of their clinical course. We previously reported that a natural product,komaroviquinone (KQN), isolated from the perennial semi-shrub Dracocephalum komarovi, i.e., komaroviquinone (KQN) and its derivative GTN024 induced the apoptosis of MM cells by producing reactive oxygen species (ROS), but both exhibited significant hematological toxicity. Aim of this study is to clarify anti-tumor activity, safety and pharmacokinetics of GTN057, an optimization compound of KQN in vivo.

METHODS

ICR/SCID xenograft model of KMS11, a t(4;14) translocation-positive MM cell line, was used for in vivo study. Mice pharmacokinetics of GTN057 and the degradation products were analyzed by LC-MS/MS.

RESULTS

Herein, our in vitro experiments revealed that GTN057 is much less toxic to normal hematopoietic cells, induced the apoptosis of both MM cell lines andpatient samples, including those with high-risk cytogenetic changes. A xenograft model of a high-risk MM cell line demonstrated that GTN057 significantly delayed the tumor growth with no apparent hematological or systemic toxicities in vivo. The pathological examination of GTN057-treated tumors in vivoshowed revealed apoptosis of MM cells and anti-angiogenesis. In addition to the production of ROS, GTN057 inhibited the downstream signaling of c-MET, a receptor tyrosine kinase a receptor forand hepatocyte growth factor (HGF) receptor. Thus, GTN057 is less toxic and is able tomay be a candidate drug for treating MM patients, via multifunctional mechanisms. We have also extensively studied the pharmacologyical analysis of GTN057. The metabolites of GTN057, (e.g.,such as GTN054), may also have anti-tumorantitumor activity.

CONCLUSION

Natural products or and their derivatives can could be good sources of antineoplastic drugs even for high-risk cancer.

A Review on Mechanistic Insight of Plant Derived Anticancer Bioactive Phytocompounds and Their Structure Activity Relationship

Cancer is a disorder that rigorously affects the human population worldwide. There is a steady demand for new remedies to both treat and prevent this life-threatening sickness due to toxicities, drug resistance and therapeutic failures in current conventional therapies. Researchers around the world are drawing their attention towards compounds of natural origin. For decades, human beings have been using the flora of the world as a source of cancer chemotherapeutic agents. Currently, clinically approved anticancer compounds are vincristine, vinblastine, taxanes, and podophyllotoxin, all of which come from natural sources. With the triumph of these compounds that have been developed into staple drug products for most cancer therapies, new technologies are now appearing to search for novel biomolecules with anticancer activities. Ellipticine, camptothecin, combretastatin, curcumin, homoharringtonine and others are plant derived bioactive phytocompounds with potential anticancer properties. Researchers have improved the field further through the use of advanced analytical chemistry and computational tools of analysis. The investigation of new strategies for administration such as nanotechnology may enable the development of the phytocompounds as drug products. These technologies have enhanced the anticancer potential of plant-derived drugs with the aim of site-directed drug delivery, enhanced bioavailability, and reduced toxicity. This review discusses mechanistic insights into anticancer compounds of natural origins and their structural activity relationships that make them targets for anticancer treatments.

Sequential Treatment of Bioresponsive Nanoparticles Elicits Antiangiogenesis and Apoptosis and Synergizes with a CD40 Agonist for Antitumor Immunity

The combination of antiangiogenesis and chemotherapy regimens with cancer immunotherapy has the potential to synergistically boost antitumor immunity. Herein, we report the construction of two bioresponsive nanoparticles, namely, Podo-NP and CbP-NP, comprising prodrugs of podophyllotoxin (Podo) and carboplatin, respectively. Sequential treatment with esterase-responsive Podo-NP, redox-sensitive CbP-NP, and a CD40 agonist promotes antitumor T cell response. Podo-NP suppresses angiogenesis by preventing proliferation and migration of endothelial cells, sprouting of neovessels, formation of tubules, and stabilization of newly formed vessels. Vascular endothelial growth factor blockade and endostatin stimulation normalize tortuous tumor vasculatures to allow efficient infiltration of effector immune cells. Subsequent treatment with CbP-NP arrests the cell-division cycle and elicits the apoptosis of tumor cells. CD40 agonist activates antigen-presenting cells to process the released tumor-associated antigens from dying tumor cells, thus reversing immunosuppressive tumor microenvironments. Sequential delivery of antiangiogenic and chemotherapeutic agents with bioresponsive NPs activates tumor microenvironments and synergizes with CD40 agonist to regress transplanted tumors and inhibit disseminated tumors in a lung cancer mouse model.

Synthesis and Biological Evaluation of 4β-N-Acetylamino Substituted Podophyllotoxin Derivatives as Novel Anticancer Agents

A series of novel podophyllotoxin derivatives obtained by 4β-N-acetylamino substitution at C-4 position was designed, synthesized, and evaluated for in vitro cytotoxicity against four human cancer cell lines (EC-9706, HeLA, T-24 and H460) and a normal human epidermal cell line (HaCaT). The cytotoxicity test indicated that most of the derivatives displayed potent anticancer activities. In particular, compound 12h showed high activity with IC₅₀ values ranging from 1.2 to 22.8 μM, with much better cytotoxic activity than the control drug etoposide (IC₅₀: 8.4 to 78.2 μM). Compound 12j exhibited a promising cytotoxicity and selectivity profile against T24 and HaCaT cell lines with IC₅₀ values of 2.7 and 49.1 μM, respectively. Compound 12g displayed potent cytotoxicity against HeLA and T24 cells with low activity against HaCaT cells. According to the results of fluorescence-activated cell sorting (FACS) analysis, 12g induced cell cycle arrest in the G2/M phase accompanied by apoptosis in T24 and HeLA cells. Furthermore, the docking studies showed possible interactions between human DNA topoisomerase IIα and 12g. These results suggest that 12g merits further optimization and development as a new podophyllotoxin-derived lead compound.

Assembled liposomes of dual podophyllotoxin phospholipid: preparation, characterization and in vivo anticancer activity

Aim: A novel amphiphilic prodrug dual podophyllotoxin (PPT) succinate glycerophosphorylcholine (Di-PPT-GPC) assembled liposomes was developed to improve efficiency of PPT. Materials & methods: Di-PPT-GPC liposomes were prepared by thin film technique and characterized by dynamic light scattering and cryo-electron microscopy. Results: In vitro release studies showed that Di-PPT-GPC liposomes could significantly release PPT in weakly acidic environment but had good stability under biological conditions. Methyl tetrazolium assay data revealed that the liposomes have comparable cytotoxicities to free PPT against MCF-7, HeLa and U87 cells. More importantly, in vivo antitumor evaluation indicated that Di-PPT-GPC liposomes exhibited favorable tumor growth inhibition without side effects. Conclusion: Di-PPT-GPC liposomes might have potential to promote the therapeutic effect of PPT for cancer therapy.

Phytochemicals and Biogenic Metallic Nanoparticles as Anticancer Agents

Cancer is a leading cause of death worldwide. Several classes of drugs are available to treat different types of cancer. Currently, researchers are paying significant attention to the development of drugs at the nanoscale level to increase their target specificity and to reduce their concentrations. Nanotechnology is a promising and growing field with multiple subdisciplines, such as nanostructures, nanomaterials, and nanoparticles. These materials have gained prominence in science due to their size, shape, and potential efficacy. Nanomedicine is an important field involving the use of various types of nanoparticles to treat cancer and cancerous cells. Synthesis of nanoparticles targeting biological pathways has become tremendously prominent due to the higher efficacy and fewer side effects of nanodrugs compared to other commercial cancer drugs. In this review, different medicinal plants and their active compounds, as well as green-synthesized metallic nanoparticles from medicinal plants, are discussed in relation to their anticancer activities.

Design, synthesis, and cytotoxicity of perbutyrylated glycosides of 4β-triazolopodophyllotoxin derivatives

A series of novel perbutyrylated glycosides of 4β-triazolopodophyllotoxin derivatives were synthesized by utilizing the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Evaluation of cytotoxicity against a panel of five human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7, SW480) using the MTT assay shows that some of these glycosylated derivatives have good anticancer activity. Among the synthesized compounds, compound 21a shows the highest activity, with IC₅₀ values ranging from 0.49 to 6.70 μM, which is more potent than the control drugs etoposide and cisplatin. Compound 21a is characterized by a perbutyrylated α-D(+)-galactosyl residue, the absence of an additional linking spacer between the sugar residue and the triazole ring, as well as a 4'-OH group on the E ring of the podophyllotoxin scaffold.

Development of predictive quantitative structure-activity relationship models of epipodophyllotoxin derivatives

Epipodophyllotoxins are the most important anticancer drugs used in chemotherapy for various types of cancers. To further, improve their clinical efficacy a large number of epipodophyllotoxin derivatives have been synthesized and tested over the years. In this study, a quantitative structure-activity relationship (QSAR) model has been developed between percentage of cellular protein-DNA complex formation and structural properties by considering a data set of 130 epipodophyllotoxin analogues. A systematic stepwise searching approach of zero tests, missing value test, simple correlation test, multicollinearity test, and genetic algorithm method of variable selection was used to generate the model. A statistically significant model (r((train))(2) = 0.721; q(cv)(2) = 0.678) was obtained with descriptors such as solvent-accessible surface area, heat of formation, Balaban index, number of atom classes, and sum of E-state index of atoms. The robustness of the QSAR models was characterized by the values of the internal leave-one-out cross-validated regression coefficient (q(cv)(2)) for the training set and r((test))(2) for the test set. The root mean square error between the experimental and predicted percentage of cellular protein-DNA complex formation (PCPDCF) was 0.194 and r((test))(2) = 0.689, revealing good predictability of the QSAR model.

Design, Synthesis and Biological Evaluation of Novel Spin-Labeled Derivatives of Podophyllotoxin

In order to design new antitumor drugs and study the relationship between antitumor and antioxidative activity of spin-labeled derivatives of podophyllotoxin, five novel pyrroline spin-labeled 4β-N-substituted-amino acid-4′-O-demethylepipodo-phyllotoxin compounds (11a-e) (Scheme 2) were synthesized and evaluated. Their cytotoxicity against three tumor cell lines (human lung carcinoma A-549, human leukemia cell HL-60 and multiple myeloma RPMI-8226) has been evaluated using a MTT-based assay in vitro. Also, we determined malondialdehyde (MDA) in liver and kidney homogenate of SD rats by the TBA method. The five new compounds showed either superior or comparable inhibitory activity against A-549, HL-60 and RPMI-8226 cell lines compared with etoposide (VP-16, 2), and all the tested compounds showed more significant antioxidant activities than VP-16. Furthermore, the partition coefficients were measured and preliminary structure-activity relationships are presented.

Synthesis, characterization, and anti-tumor activities of some transition metal(II) complexes with podophyllic acid hydrazide

Four transition metal(II) complexes with podophyllic acid hydrazide (HL) were prepared and characterized by elemental analysis, complexometric titration, thermal analysis, conductivity, IR, and 1H NMR. The complexes have the general formula ML2 · nH2O, where M = Zn, Cu, Co, and Ni, n = 2 or 0. Anti-tumor activities of podophyllotoxin, HL, ZnL2 · 2H2O, and NiL2 were tested by both the MTT and the SRB method. The results show that the activities of the complexes against the tumor cells tested are superior to HL and the anti-tumor activity of NiL2 is even similar to that of podophyllotoxin.

Camptothecin and podophyllotoxin derivatives: inhibitors of topoisomerase I and II - mechanisms of action, pharmacokinetics and toxicity profile

Camptothecins represent an established class of effective agents that selectively target topoisomerase I by trapping the catalytic intermediate of the topoisomerase I-DNA reaction, the cleavage complex. The water-soluble salt camptothecin-sodium - introduced in early trials in the 1960s - was highly toxic in animals, whereas the semisynthetic derivatives irinotecan and topotecan did not cause haemorrhagic cystitis because of their higher physicochemical stability and solubility at lower pH values. Myelosuppression, neutropenia and, to a lesser extent, thrombocytopenia are dose-limiting toxic effects of topotecan. In contrast to the structurally-related topotecan, irinotecan is a prodrug which has to be converted to SN-38, its active form. SN-38 is inactivated by conjugation, thus patients with Gilbert's syndrome and other forms of genetic glucuronidation deficiency are at an increased risk of irinotecan-induced adverse effects, such as neutropenia and diarrhoea. The cytotoxic mechanism of podophyllotoxin is the inhibition of topoisomerase II. Common adverse effects of etoposide include dose-limiting myelosuppression. Hypersensitivity reactions are more common with etoposide and teniposide than with etoposide phosphate because the formulations of the former contain sensitising solubilisers. Leukopenia and thrombocytopenia occur in 65% and 80%, respectively, of patients after administration of conventional doses of teniposide. Anorexia, vomiting and diarrhoea are generally of mild severity after administration of conventional doses of topoisomerase II inhibitors. Clinical pharmacokinetic studies have revealed substantial interindividual variabilities regarding the area under the concentration-time curve values and steady-state concentrations for all drugs reviewed in this article. Irinotecan, etoposide and teniposide are degraded via complex metabolic pathways. In contrast, topotecan primarily undergoes renal excretion. Regarding etoposide and teniposide, the extent of catechol formation over time during drug metabolism may be associated with a higher risk for secondary malignancies.

Etoposide: twenty years later

Since the beginning of its clinical development 20 years ago, etoposide has become an important and widely used agent in clinical oncology. Its integral role in the treatment of germ cell tumors and small-cell lung cancer seems unlikely to diminish in the future, and its use in non-Hodgkin's lymphoma and in various high dose regimens will probably continue to increase. Active investigation continues regarding the optimal dose and schedule of etoposide, and it is likely that these investigations will result in further improvement of its clinical activity in patients with sensitive tumor types. Continued clinical investigation may result in the identification of active etoposide containing combination regimens for ovarian cancer, breast cancer, and some of the childhood malignancies. Exciting possibilities for the future include exploration of etoposide in combination with the topoisomerase I inhibitors, as well as the development of drugs to reverse drug resistance. During the next 10 years, the applications and importance of this unique drug will continue to increase.

Weekly carboplatin and VM-26 for elderly patients with small-cell lung cancer

BACKGROUND

Elderly patients are excluded from chemotherapy trials, even though they represent 25% of those with small cell lung cancer. An effective chemotherapy regimen with limited toxicity should be developed with the aim not only of increasing the survival of these patients, but also of improving their quality of life and their independence.

PATIENTS AND METHODS

Twenty-four patients with a median age of 72 years and small-cell lung cancer (SCLC) were included in the trial. Chemotherapy consisted of a weekly intravenous regimen of Carboplatin 80 mg/m2 and Teniposide 80 mg/m2 administered on an outpatient basis.

RESULTS

Eight patients had limited and 16 extensive disease. After a median of 12 chemotherapy courses (2-31) the overall response rate was 66.7% (95% Cl: 44.7-84.4), with 5 patients in complete and 11 in partial remission. The median overall survival was 33 weeks, with 4 patients alive at more than one year. Improvement of symptoms occurred in 86% of patients. Toxicity, mainly hematological, was moderate.

CONCLUSIONS

Weekly Carboplatin and VM-26 is an effective and non-toxic regimen for elderly patients, leading to results similar to those obtained with a more intensive regimen in a younger age group.

A study of dose escalation of teniposide (VM-26) plus cisplatin (CDDP) with recombinant human granulocyte colony-stimulating factor (rhG-CSF) in patients with advanced small cell lung cancer

A dose escalation study of teniposide (VM-26) plus cisplatin (CDDP) was carried out using recombinant human granulocyte colony-stimulating factor (rhG-CSF) in 46 previously untreated patients with advanced small cell lung cancer (SCLC). The dose of CDDP was 80 mg/m2/day intravenously (i.v.) (day 1) and VM-26 was escalated from 60 mg/m2/day to 80, 100 and 120 mg/m2/day i.v. x 5 days for four cycles. The dose of rhG-CSF was 90 micrograms/m2/day subcutaneously for 13 days. The feasibility of the regimen at the starting dose level of VM-26 with or without rhG-CSF was initially examined in 10 patients chosen through random allocation. WHO grade 4 neutropenia was observed in 17% (three out of 18 courses) of patients in the rhG-CSF group and in 63% (12 out of 19 courses) of the control group (P < 0.01). The number of patients with febrile episodes (> 38 degrees C) over the four courses of chemotherapy was 1 in the rhG-CSF group and 4 in the control group. According to these results, all 36 patients received rhG-CSF in the dose escalation stage. The incidence of WHO grade 4 neutropenia at the dose levels of 60, 80, 100 and 120 mg/m2/day of VM-26 was 66, 57, 76 and 85%, respectively (P > 0.1). The incidence of grade 4 thrombocytopenia was 19, 31, 18 and 46%, respectively (P > 0.1). The overall response rate was 100% in patients with limited stage SCLC and 83% in patients with extensive stage SCLC. The actual administered VM-26 dose per week at the dose level of 100 mg/m2/day was 1.6-fold higher than the planned starting dose (60 mg/m2/day) per week. At the dose level of 120 mg/m2/day, 50% of patients developed WHO grade 4 leucopenia, which lasted longer than 1 week and 67% of the patients had WHO grade 3 or 4 diarrhoea. At this same dose, all patients had at least one febrile episode (> 38 degrees C), and 1 patient died of cerebral bleeding with severe thrombocytopenia. The median survival time of all patients was 451 days (411 days, extensive disease; 497 days, limited disease). VM-26 plus CDDP with rhG-CSF was active in previously untreated patients with SCLC. The recommended dose of VM-26 in combination with CDDP for a phase II study is 100 mg/m2/day for 5 days with rhG-CSF support.

A randomised study of bolus vs continuous pump infusion of ifosfamide and doxorubicin with oral etoposide for small cell lung cancer

One hundred and fifty-nine previously untreated patients with small cell lung cancer (SCLC), who were not eligible for intensive chemotherapy, were entered into a randomised study of intravenous (i.v.) doxorubicin and ifosfamide (with mesna) and oral etoposide. The i.v. drugs were given either by bolus therapy or by a continuous infusion (CI) pump over 7 days via a central venous line. Therapy was given for 6 weeks only. On weeks 1, 3 and 5 IV doxorubicin 35 mg m-2 was given with 5 days of oral etoposide 100 mg m-2 daily. On weeks 2, 4 and 6 IV ifosfamide 5 g m-2 was given with equidose mesna. The overall median survival was 25 weeks for patients in the bolus arm and 30 weeks for the CI therapy (P = 0.45). The overall response rate was 64% (18% complete response-CR) and 69% (30% CR) respectively (P = 0.13). The median WHO score for haematological toxicity was 4 for bolus therapy and 3 for CI therapy (P = 0.0007). Despite a trend for less supportive care for patients on CI therapy there were no significant differences in the use of i.v. antibodies and blood or platelet transfusions. There were fewer treatment delays due to myelotoxicity in the CI arm (P = 0.04). The median WHO score for non-haematological toxicity was 2 in both treatment groups. There was significantly less nausea (P = 0.037) but more mucositis (P = 0.01) in the CI arm. Weekly chemotherapy using CI treatment was as effective as bolus therapy. It was well accepted by patients. The assessment of quality of life in a subgroup of patients showed a statistically significant reduction in anxiety and depression for both groups of patients during therapy.

Treatment of early recurrent medulloblastoma in children with cisplatin and etoposide: a preliminary report

The prognosis of recurrent medulloblastoma remains extremely poor. Combination chemotherapy with cisplatin (CDDP) and etoposide (VP-16) was given to five children with early recurrent medulloblastoma. As a rule, CDDP 20 mg/m2 per day and VP-16 60 mg/m2 per day were administered intravenously for 5 days. This cycle was repeated three times at 4-week intervals. After this therapy, cerebellar signs improved in one case and were unchanged in four cases. Weakness and sensory disturbance, however, improved in three of four patients. Moreover, neck and/or back pain resolved in all these four. Radiological findings improved in three cases. Myelosuppression appeared in all patients, but receded rapidly. No other significant complications were noticed. Two patients died 5 and 6 months after this therapy. These results seem to suggest that this therapy has a use in improving neurological symptoms, particularly neck and/or back pain, although its efficacy is limited.

Phase II study of teniposide in patients with AIDS-related Kaposi's sarcoma

Antitumour activity of cytotoxic agents, evaluated in patients with AIDS-related Kaposi's sarcoma (KS), is about 30-80%. However, responses are mostly partial and short. Experience with etoposide is similar. Teniposide has a longer elimination half-life and superior antitumour activity compared with etoposide in some experimental models. Thus a phase II trial was done in 25 patients with AIDS-related KS. Teniposide was given by 60-min infusion at 360 mg/m2 every 3 weeks. 10 (40%) showed a partial response, median duration of 9 (6-20) weeks. The main side-effects were leukopenia, thrombocytopenia, nausea and vomiting, alopecia and mucositis.

Gestational trophoblastic disease: what have we learned in the past decade?

Hydatidiform moles can be classified into two distinct entities: complete and partial. Complete moles are androgenetically derived, are characterized by a predominance of the 46,XX karyotype, and are associated with a significantly higher incidence of malignant sequelae than are partial moles. A subset of complete moles resulting from dispermy are heterozygous (46,XY) and appear to be associated with the greatest risk of malignancy. Free subunits of human chorionic gonadotropin, beta core fragments, and acidic variants of human chorionic gonadotropin can now be readily measured by radioimmunoassays, fluoroimmunoassays, or isoelectric focusing techniques. Determination of these markers can be of value not only in monitoring response to therapy, but also as prognostic indicators. A subgroup of patients, traditionally classified as "high risk" or poor prognosis, who show poor responses to conventional combination chemotherapy have recently been designated as "ultra-high-risk" patients. They require more complex chemotherapy and possibly surgery and radiotherapy to achieve remission. The development of chemotherapy over the past decade, including the introduction of etoposide and cisplatin into current protocols and the treatment of patients with advanced gestational trophoblastic disease, are considered in this review.

Effects of the lipophilic anticancer drug teniposide (VM-26) on membrane transport

The epipodophyllotoxin glucopyranosides have previously been shown to interact with membrane lipids and to alter the activity of several lipid-embedded membrane proteins. To determine if these agents are acting as general membrane perturbants, we have further examined their effects on membrane processes in Ehrlich ascites tumor cells. [3H]VM-26 and [3H]VP-16 were taken up rapidly and concentrated within the cells in proportion to their lipophilicity. Neither agent was found to have any significant effect on the influx of L-[3H]leucine or alpha-[3H]aminoisobutyric acid. Likewise, these drugs had no significant effects on the hexose transporter. The nucleoside transporter, which is structurally and functionally similar to the hexose transporter, was dramatically affected, however. VM-26 was a non-competitive inhibitor of equilibrium-exchange influx of cytosine arabinoside in Ehrlich cells with a Ki of 15 microM. Equilibrium-exchange influx increased with temperature in control cells (Q10 = 2) but not in VM-26-treated cells; thus, VM-26 was a more potent inhibitor at higher temperatures. VM-26 also significantly reduced zero-trans influx in Ehrlich, P388, L5178Y, and ML-1 cells, and these effects were immediate in onset. VM-26 inhibited high-affinity binding of the nucleoside transport inhibitor nitrobenzylmercaptopurine riboside (NBMPR), but VM-26 enhanced non-specific NBMPR binding to Ehrlich cells. The apparent specificity of the epipodophyllotoxins for the nucleoside transporter is discussed.

Clinical pharmacology of cancer chemotherapy in children

The pharmacokinetics of most anticancer drugs are highly variable in children, and are commonly different when children are compared to adults. Several recent studies have demonstrated that variability in systemic exposure due to interpatient pharmacokinetic variability, may be related to the probability of oncolytic effects or toxicity for some anticancer drugs. This review has exemplified differences in the clinical pharmacology of several anticancer drugs, when children are compared to adults. Such age-related differences in the pharmacokinetics and pharmacodynamics of these drugs, together with biologic differences between pediatric and adult cancers, provide the rationale for systematically conducting pediatric phase I through IV studies of anticancer drugs and denote the risks of relying on adult trials to identify new therapeutic strategies for childhood cancers.

Etoposide in leukemia, lymphoma and bone marrow transplantation

Etoposide, an epipodophyllotoxin structurally related to vincristine, is active in solid tumors. Trials of etoposide in hematologic malignancies, particularly leukemia and lymphoma, were initiated in 1973. Subsequent studies indicate that etoposide, either as a single agent or in combination with other drugs, is active in acute myelogenous leukemia, non-Hodgkin and Hodgkin lymphoma. Etoposide may be effective in acute lymphoblastic leukemia, but it is inactive in chronic myelogenous leukemia. The major toxicity of etoposide is myelosuppression. Non-hematologic toxicity is relatively mild at doses up to 2000 mg/m2. This feature favors its use in high dose regimens such as those employed before bone marrow transplantation. Preliminary studies of etoposide in autologous bone marrow transplantation in lymphoma and Hodgkin disease are promising. Studies of high dose etoposide in combination with other chemotherapeutic agents or in the context of bone marrow transplantation are in progress.

Stability of solutions of antineoplastic agents during preparation and storage for in vitro assays. III. Antimetabolites, tubulin-binding agents, platinum drugs, amsacrine, L-asparaginase, interferons, steroids and other miscellaneous antitumor agents

The stability of solutions of the antitumour antimetabolites, vinca alkaloids, podophyllotoxins, interferons, steroids and platinum drugs as well as maytansine, asparaginase, amsacrine, flavone-8-acetic acid, mitoguazone, and N-phosphonoacetyl-L-aspartate (PALA) is reviewed. Much of the published work has been done with biological, not stability-indicating, assays; thus, the relevant results should be used with caution. With this proviso, almost all of these drugs can be stored in solution for several days at room temperature or 4 degrees C. Most reports also suggest that the drugs that have been tested are stable when frozen in solution. For a number of the drugs, particular precautions are required; for instance, amsacrine should not be mixed with chloride-containing solutions, whereas cisplatin is most stable in solutions containing greater than 0.1 M chloride.

Effects of the ortho-quinone and catechol of the antitumor drug VP-16-213 on the biological activity of single-stranded and double-stranded phi X174 DNA

We have studied the effects of the recently reported two new metabolites of the antitumor agent VP-16-213, the ortho-dihydroxy derivative or catechol and the ortho-quinone, on the biological activity of single-stranded and double-stranded phi X174 DNA, the binding of the metabolites to calf thymus DNA and the conversion of the catechol into the ortho-quinone. Evidence was obtained for the oxidation of the catechol into the ortho-quinone and for the fact that the ortho-quinone is the metabolite of VP-16-213 responsible for its binding to rat liver microsomal proteins. The catechol and ortho-quinone of VP-16-213 were found to bind 7-9 times more strongly to calf thymus DNA than VP-16-213 itself. In contrast to the parent compound VP-16-213, the catechol as well as the ortho-quinone inactivated both single-stranded (ss) and double-stranded (RF) biologically active phi X174 DNA. The mean T37-values for inactivation of ss and RF phi X174 DNA by 2.2 x 10(-4)M catechol at 37 degrees and pH 7.4 were 96 and 640 min, respectively. Reduction of the ortho-quinone by NADPH cytochrome P-450 reductase resulted in formation of the catechol. The system ortho-quinone/NADPH cytochrome P-450 reductase inactivated ss phi X174 DNA with a mean T37-value of 454 min, and this inactivation was inhibited by DMSO. The mean T37-value for inactivation of ss phi X174 DNA by 1.8 x 10(-4) M ortho-quinone at 37 degrees and pH 4.0 was 24 min. The chemical stability of the ortho-quinone and the extent of inactivation of ss phi X174 DNA by the ortho-quinone were both pH-dependent: at higher pH the ortho-quinone was less stable and gave less inactivation of DNA. The aqueous decomposition product(s) of the ortho-quinone formed at pH 7.4 inactivated ss phi X174 DNA with a mean T37-value of 175 min. The rate of inactivation of RF phi X174 DNA by the ortho-quinone at pH 4.0 was twice as low as the rate of inactivation of ss phi X174 DNA: T37 = 49 min. When using excision repair deficient E. coli mutants (uvrA- or uvrC-), a higher inactivation of RF phi X174 DNA was found: T37 = 29 min for uvrA- E. coli, indicating that a part of the DNA damage introduced by the incubation with ortho-quinone is removed by excision repair.(ABSTRACT TRUNCATED AT 400 WORDS)

Structure-bioactivation relationship of a series of podophyllotoxin derivatives

With the aim of elucidating the structural requirements for O-demethylation of the antitumor agent VP-16-213 by cytochrome P-450, the binding of a series of podophyllotoxin derivatives to rat liver microsomal cytochrome P-450 was studied. The examined podophyllotoxin derivatives were: VP-16-213, VM-26, podophyllotoxin, 4'-demethylepipodophyllotoxin (the aglycone of VP-16-213 and VM-26) and 3,5-dimethoxy-4-hydroxytoluene (a model compound for the E-ring of VP-16-213). The binding to phenobarbital (Pb)-induced microsomes was more extensive than that to 3-methylcholanthrene (3-MC)-induced microsomes. Experiments on the binding to cytochrome P-450 in Pb-induced microsomes led to the following findings: (a) the presence of the polycyclic skeleton is necessary for binding; (b) the presence of the sugar moiety gives a further extension of binding, and changes in the sugar moiety affect binding; (c) binding increases on elevation of hydrophobicity; (d) the E-ring itself does not bind. For binding to cytochrome P-450 in 3-MC-induced microsomes conclusions (a) and (d) appeared to hold true. For the O-demethylation of the podophyllotoxin derivatives containing the dimethoxyphenol ring by Pb- and 3-MC-induced microsomes, the following order was observed: VM-26 greater than VP-16-213 greater than aglycone much greater than E-ring. A similar sequence was observed for the cytotoxicity against Chinese hamster ovary cells.

Teniposide (VM-26) in patients with advanced refractory ovarian cancer: a phase II study of the Netherlands Joint Study Group for Ovarian Cancer

In 23 evaluable patients with advanced ovarian epithelial cancer refractory to combination therapy with cisplatin and an alkylating agent, teniposide (VM-26) was administered as a short-term i.v. infusion at a dose of 100 mg/m2 on days 1 and 2, every 3 weeks. Toxicity was moderate and comparable to the pattern known from other studies. No objective response has been observed, showing that teniposide is not active as second-line therapy in this disease.

Chemotherapy for small cell lung cancer: induction and reinduction with VOCA

Sixty-five patients with small cell lung cancer were treated with VP16, vincristine, cyclophosphamide, and doxorubicin (VOCA) intravenously at three-week intervals. Patients with limited disease received four cycles with responders receiving radiation to the primary site and prophylactic cranial irradiation. Patients with extensive disease received chemotherapy only. Of 59 patients evaluable for chemotherapy response, eight (14%) achieved complete remission and 30 (51%) partial remission. Major side-effects included myelosuppression, alopecia, nausea, and vomiting. Reinduction with VOCA at relapse yielded objective or subjective response in four of seven patients. This regimen is active in small cell lung cancer and was well tolerated by patients. Reinduction of response was possible in a small number of patients retreated and may provide useful palliation for those who relapse when treatment is discontinued.

The clinical pharmacology of etoposide and teniposide

Etoposide and teniposide are semisynthetic derivatives of podophyllotoxin and are increasingly used in cancer medicine. Teniposide is more highly protein-bound than etoposide, and its uptake and binding to cells is also greater. Etoposide and teniposide are phase-specific cytotoxic drugs acting in the late S and early G2 phases of the cell cycle. They appear to act by causing breaks in DNA via an interaction with DNA topoisomerase II or by the formation of free radicals. Teniposide is more potent as regards the production of DNA damage and cytotoxicity. Most studies show a biexponential decay following intravenous administration of etoposide and teniposide. The terminal elimination half-life of etoposide is less than that of teniposide, and the plasma and renal clearances of etoposide are greater. The peak plasma concentrations of drug and the area under the concentration versus time curve are linearly related to the intravenous dose of both drugs. Considerable interpatient variability of pharmacokinetic parameters exists following intravenous etoposide and teniposide. Various metabolites of etoposide and teniposide have been identified but their detection and quantitation are disputed. Approximately 30 to 70% of a dose of etoposide is accounted for by excretion, whereas the figure appears to be only 5 to 20% for teniposide. The bioavailability of oral etoposide is about 50% but its absorption is not linear with increasing dose within the range in clinical use. There is considerable inter- and intrapatient variability in the pharmacokinetics of oral etoposide. There is no evidence of accumulation of etoposide and teniposide after multiple consecutive doses by the intravenous or oral routes. The exact roles of the liver and kidney in metabolism and excretion of etoposide and teniposide are uncertain. Etoposide has been shown to be a highly schedule-dependent drug in clinical studies. This together with the phase-specific action of etoposide and teniposide and their increasingly widespread use in cancer medicine make the clinical pharmacology of these drugs of great clinical importance.

Mutagenicity and clastogenicity of teniposide (VM-26) in L5178Y/TK +/- -3.7.2C mouse lymphoma cells

The antitumor drug teniposide (VM-26) is a potent inducer of DNA breaks (Long et al., Cancer Res., (1985) 45, 3106), but it is only weakly mutagenic at the hprt locus in CHO cells (Singh and Gupta, Cancer Res., (1983) 43, 577). In the present study, the mutagenic and clastogenic activities of teniposide were evaluated in L5178Y/TK +/- -3.7.2C mouse lymphoma cells. Although teniposide is a weak mutagen at the hprt locus, it is a potent mutagen at the tk locus, with as little as 0.5 ng/ml producing 220 TK mutants/10(6) survivors at 96% survival (background = 100/10(6) survivors). This same dose of teniposide induced 38 aberrations per 100 metaphases (background = 7/100 cells). At 7 ng/ml, teniposide induced approximately 2700 TK mutants/10(6) survivors at approximately 10% survival. At the highest dose sampled for aberration analysis (5 ng/ml), teniposide induced 44 aberrations/100 cells. Most of the aberrations were chromosomal rather than chromatid events. As expected for a compound acting primarily by a clastogenic mechanism, most of the TK mutants were small colonies. Thus, teniposide is a potent clastogen, and it is a potent mutagen at the tk locus but not at the hprt locus. These results support the hypothesis that the location of the target gene affects the ability of the assay to detect both intragenic events and events causing functional multilocus effects. Thus, a heterozygous locus (like tk) but not a functionally hemizygous locus (like hprt) may permit the detection of mutagens that act primarily by a clastogenic mechanism. Because teniposide induces topoisomerase II-associated DNA breaks, and because there is evidence that teniposide may not interact directly with DNA, we discuss the possibility that the potent clastogenic/mutagenic activity of teniposide may be mediated by topoisomerase II.

Purified podophyllotoxin (CPH-86) inhibits lymphocyte proliferation but augments macrophage proliferation

Purified podophyllotoxin (CPH-86) is an inhibitor of microtubular aggregation used in the treatment of cancer, psoriasis and rheumatoid arthritis. To better understand its immunopharmacology we examined its effects on human lymphocytes and monocytes and guinea pig macrophages. CPH-86 inhibits mitogen-induced human lymphocyte proliferation and macrophage growth factor-stimulated macrophage proliferation with ID50s of approximately 10(-7) M. The effect of CPH-86 on lymphocytes in conjunction with mitogen is nonlethal, evident during the early but not the late phases of proliferation, and associated with early increases in cyclic AMP levels. In contrast to these obviously inhibitory effects, CPH-86 (10(-7) M) alone induces IL-1 by human monocytes and, with mitogen, it induces IL-2 production by human lymphocytes. It directly stimulates macrophage proliferation and potentiates the effects of low doses of macrophage growth factor to do so. The latter effects may be mediated by colony stimulating factor production. The effects of CPH-86 are not mediated by inhibition of prostaglandin synthesis. The stimulation of monokine and lymphokine production by CPH-86 may represent positive features of its action and may be immunotherapeutic.

Pharmacokinetics of high dose etoposide (VP 16-213)

This paper describes the pharmacokinetics of etoposide in cancer patients after high dose administration (up to 3.5 g/m2). High performance liquid chromatography with electrochemical detection was used to determine etoposide, cis etoposide and the glucuronide of etoposide in plasma, bile, cerebro-spinal fluid, urine, saliva and ascites, the detection limit being 2 ng etoposide/ml plasma. The plasma concentration time curve shows a tri-phasic decay. The terminal phase is very slow. It was concluded that etoposide is strongly bound in the peripheral compartment. The volume of the central compartment varied from 7.4 to 20.1 l and the steady state volume of distribution from 3.1 to 7.8 l/m2. Relatively high concentrations of etoposide were found in saliva, bile, ascites and urine and low concentrations in cerebro-spinal fluid. The total body clearance varied from 12.0 to 26.8 ml/min/m2, and 26.2 to 53.4% was excreted as unchanged etoposide into the urine and 8.3 to 17.3% as glucuronide into the urine. Very low amounts of the trans hydroxy acid of etoposide and the cis etoposide were detected in the urine. Glucuronides were found in urine and duodenal fluid but not in plasma.

A phase I-II study of cytosine arabinoside, daunorubicin, and VP16-213 in adult patients with acute non-lymphocytic leukemia

The combination cytosine arabinoside (ara-C), daunorubicin, and VP 16-213 was studied in 28 patients with acute non-lymphocytic leukemia to define the toxicity of the combination and assess its efficacy. Of 21 previously untreated patients, 16 (76%) achieved a complete response (CR) with the median remission duration not reached but exceeding 25 weeks. For CR patients, the median number of days with neutrophils less than 500/microliter was 19. The median survival for patients with CR is 60 weeks. Two of seven previously treated patients achieved CR for 11 weeks and in excess of 36 weeks, respectively. At the initial VP16-213 dose of 100 mg m-2 per day for seven days, severe stomatitis was seen in 38% of courses but was less with dose reduction to 75 mg m-2 per day for seven days. Other toxicity was similar to previous experience with ara-C and daunorubicin alone.

Variable bioavailability following repeated oral doses of etoposide

Following oral administration considerable variation in the bioavailability of etoposide has been reported between patients and with different formulations of the drug. The variation within patients following repeated doses is unknown and has therefore been studied in seven patients receiving therapy on three successive days for relapsed small cell lung carcinoma. Etoposide was administered at a dose of 400 mg orally and plasma concentrations were measured using high-performance liquid chromatography. Within-patient coefficients of variation over three successive days ranged over 19-45% for peak plasma concentrations and 16-53% for the area under the plasma concentration-time curve. There was no evidence of a trend to suggest improving or worsening absorption and accumulation did not occur. Urinary excretion was less than 25% and showed no increase over the 3 days. These data indicate that etoposide bioavailability is not constant and oral therapy may lead to unsuspected underdosing or unexpected toxicity in schedules extending over several days. Monitoring blood concentrations for a single day following oral therapy may give a misleading idea of the total bioavailability of etoposide during a course of therapy. Studies of the relationship between the pharmacokinetics of prolonged schedules of etoposide and disease outcome may lead to unreliable conclusions unless intravenous etoposide is used.

Phase II trial of VP-16-213 in advanced ovarian carcinoma

We have reevaluated the effectiveness of VP-16-213 in advanced ovarian carcinoma. Twenty-five patients with measurable disease were treated for 3 days every 2 weeks with an escalating dose of the oral preparation. Twenty-two percent of 23 evaluable patients responded including one complete response. The median duration of response was 20 weeks and median survival 32 weeks. Toxicity was mild. The response rate observed is relatively high in patients pretreated with cis-platinum. VP-16-213 deserves further study, especially in combination with cis-platinum.

Inactivation of phi X174 DNA by the ortho-quinone derivative or its reduction product of the antitumor agent VP 16-213

Biologically active phi X174 DNA is inactivated by the ortho-quinone derivative of the antitumor agent VP 16-213, but not by VP 16-213 itself, VP 16-213 phenoxy radical or aqueous decomposition product(s) of the ortho-quinone. Reduction of the ortho-quinone by cytochrome P-450 reductase and NADPH results in deactivation of the ortho-quinone towards anti-phi X174 DNA activity. However, compared with the parent compound VP 16-213, reduction of the ortho-quinone results in substantial damage towards DNA.

The effect of food and concurrent chemotherapy on the bioavailability of oral etoposide

There is no information on the effect of food or concurrent drug administration on the bioavailability of oral etoposide, despite the fact that treatment is frequently administered over several days and most often in combination with other cytotoxic agents. The influence of these factors has been studied in 11 patients, receiving combination cytotoxic therapy for extensive small cell lung carcinoma. Neither food nor concurrent oral or intravenous chemotherapy had a significant effect on the mean plasma concentrations of etoposide, achieved following oral administration. Wide variation in peak plasma concentrations and in area under the concentration time curve (AUC) occurred both between and within patients. It appears unnecessary for patients receiving etoposide (at 100 mg) to fast prior to drug administration. Furthermore, oral etoposide (at 100 mg and at 400 mg) may be given in combination with other cytotoxic agents without compromising its bioavailability.

Drug monitoring of etoposide (VP16-213). I. A combined method of liquid chromatography and mass spectrometry

Drug monitoring is performed by means of sample extraction, sample purification by high-performance liquid chromatography (HPLC), and sample detection by time-of-flight mass spectrometry. This mass spectrometry utilizing 252Cf fission fragment-induced ionization and desorption of nonvolatile compounds is suitable as a universal, nondestructive detector in HPLC. Liquid chromatography and mass spectrometry are combined, so that mass analysis can be operated online and offline to the fractional sampling of the effluent and the samples can still be recovered. As an alternative to HPLC separation, samples can be purified by thin-layer chromatography (TLC), resulting an offline TLC + MS combination. Preliminary pharmacokinetic data for etoposide (VP16-213) together with calibration data are presented, and are discussed with reference to the sensitivity and detection limit of the new experimental method.

Skin ulceration potential without therapeutic anticancer activity for epipodophyllotoxin commercial diluents

The epipodophyllotoxin derivatives, etoposide (VP-16) and teniposide (VM-26), are highly lipophilic anticancer drugs supplied with novel commercial solvent systems. A BALB/c mouse skin toxicity model was used to evaluate the ulcerative potential of intradermal (ID) VP-16 and its lipophilic solvent system along with the main ingredient of the VM-26 solvent, polyethoxylated castor oil (PECO). ID VP-16 caused dose-dependent ulceration following 0.17 mg, 0.33 mg (50 mg/M2) or 1.0 mg (150 mg/M2). Both normal saline (0.05 ml ID) and hyaluronidase (7.5 u ID) were effective as local VP-16 antidotes, presumably by diluting out the extravasated drug. The VP-16 solvent alone was as toxic as the 1.0 mg (undiluted) ID VP-16 injection. ID PECO was mildly ulcerative in mouse skin. When given to P-388 lymphocytic leukemia-bearing mice, both VP-16 (24 mg/kg IP for 3 doses) and VM-26 (8 mg/kg IP for 2 doses) were active, producing increased life spans (ILS) of 160% and 90%, respectively. The solvents, given IP at the same schedule, did not increase or decrease the life span of tumor-bearing mice, but did increase morbidity. In an in vitro human tumor clonogenic assay (WiDr colon carcinoma and HEC-1A endometrial carcinoma in soft agar), both VP-16 and VM-26 showed moderate to complete inhibition of tumor colony forming units (TCFUs) by continuous exposure. 1-h drug exposures were marginally active at reducing TCFUs. None of the epipodophyllotoxin diluents at clinical concentrations reduced TCFUs. At very high concentrations, both epipodophyllotoxins were cytotoxic. They were more effective at reducing TCFUs when plated as a continuous exposure rather than a 1-h exposure.