Etoposide

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Etoposide (VP-16) is the first agent recognized as a topoisomerase II inhibitor of anticancer drug with IC50 of 59.2 μM.

The activity of the topoisomerase II enzyme on re-ligation of DNA strands is interrupted by etoposide. A ternary complex with DNA is formed by etoposide, and causes DNA strands to break [1]. The enzyme was more important in cancer cell than healthy cells, because cancer cells divided more rapidly. So etoposide induced apoptosis of the cancer cells [2]. Etoposide exhibited cytotoxic activity against HepG2 and MOLT-3 cancer cells with IC50 of 30.16 μM and 0.051μM [3]. The IC50 values of etoposide against the tumor cell lines of BGC-823, HeLa, and A549 were 43.74 ± 5.13, 209.90 ± 13.42, and 139.54 ± 7.05 μM, respectively [4].

References:
[1]. Pommier Y, Leo E, Zhang H, Marchand C. DNA topoisomerases and their poisoning by anticancer and antibacterial drugs. Chem Biol. 2010 May 28;17(5):421-33.
[2]. Gordaliza M, García PA, del Corral JM, Castro MA, Gómez-Zurita MA. Podophyllotoxin: distribution, sources, applications and new cytotoxic derivatives. Toxicon. 2004 Sep 15;44(4):441-59.
[3]. Pingaew R, Mandi P, Nantasenamat C, Prachayasittikul S, Ruchirawat S, Prachayasittikul V. Design, synthesis and molecular docking studies of novel N-benzenesulfonyl-1,2,3,4-tetrahydroisoquinoline-based triazoles with potential anticancer activity. Eur J Med Chem. 2014 May 6;81C:192-203.
[4]. Xiao L, Zhao W, Li HM, Wan DJ, Li DS, Chen T, Tang YJ. Design and synthesis of the novel DNA topoisomerase II inhibitors: Esterification and amination substituted 4'-demethylepipodophyllotoxin derivates exhibiting anti-tumor activity by activating ATM/ATR signaling pathways. Eur J Med Chem. 2014 Jun 10;80:267-77.

Etoposide: four decades of development of a topoisomerase II inhibitor.[Pubmed:9893622]

Eur J Cancer. 1998 Sep;34(10):1514-21.

Podophyllin-containing materials have been used as folk medicines for centuries. In the 1950s, scientists began a search to identify a more effective podophyllotoxin derivative. These efforts eventually resulted in the development of a new class of antineoplastic agents which target the DNA unwinding enzyme, topoisomerase II. The history of the development of one of the first identified topoisomerase II inhibitors, Etoposide, is reviewed in this paper. Critical developments in Etoposide's mechanism of action, pharmacology and administration schedule are summarised. The clinical benefits of the recently marketed Etoposide prodrug, Etoposide phosphate (Etopophos) are also detailed. The current status of other clinically approved anticancer agents which target topoisomerase II is briefly reviewed.

Reconstitution of caspase 3 sensitizes MCF-7 breast cancer cells to doxorubicin- and etoposide-induced apoptosis.[Pubmed:11196185]

Cancer Res. 2001 Jan 1;61(1):348-54.

MCF-7, a breast cancer-derived cell line, is deficient of caspase 3 and relatively insensitive to many chemotherapeutic agents. To study the association of caspase 3 deficiency and chemotherapeutic resistance, we reconstituted caspase 3 in MCF-7 cells and characterized their apoptotic response to doxorubicin and Etoposide. Western blots demonstrated that caspase 3 was constitutively expressed in the reconstituted MCF-7 cells. Both morphological observation and survival assays showed that caspase 3 reconstitution significantly sensitized MCF-7 cells to both drugs. Remarkably increased activation of caspases 3, 6, and 7, cleavage of cellular death substrates, and DNA fragmentation were detected in the reconstituted MCF-7 cells after drug treatment. Together, these data demonstrated a specific role for caspase 3 in chemotherapy-induced apoptosis and in activation of caspases 6 and 7. Our results also suggest that caspase 3 deficiency may contribute to chemotherapeutic resistance in breast cancer.

Sequential dose-intensive paclitaxel, ifosfamide, carboplatin, and etoposide salvage therapy for germ cell tumor patients.[Pubmed:10715285]

J Clin Oncol. 2000 Mar;18(6):1173-80.

PURPOSE: To evaluate the efficacy and toxicity of sequential, dose-intensified chemotherapy with paclitaxel/ifosfamide and carboplatin/Etoposide administered plus peripheral blood-derived stem-cell (PBSC) support for patients with germ cell tumors (GCT) who have unfavorable prognostic features in response to conventional-dose salvage programs. Carboplatin was dose escalated by target area under the curve (AUC; in [milligrams per milliliter] x minutes) among patient cohorts, and pharmacokinetic studies were performed for comparison. PATIENTS AND METHODS: Thirty-seven previously treated patients who had cisplatin-resistant GCT and unfavorable prognostic features for response to conventional-dose salvage therapy were treated. Two cycles of paclitaxel 200 mg/m(2) plus ifosfamide 6 g/m(2) were given 2 weeks apart with leukapheresis, followed by three cycles of carboplatin plus Etoposide given 14 to 21 days apart with reinfusion of PBSCs. The dose of Etoposide was 1, 200 mg/m(2), and the carboplatin target AUC ranged among cohorts from 12 to 32 (mg/mL) x min. Pharmacokinetic studies of carboplatin were performed for comparison of target to measured AUC. RESULTS: Twenty-one patients (57%) achieved a complete response and an additional two patients (5%) achieved a partial response with normal tumor markers; therefore, 23 (62%) achieved a favorable response. Eight patients relapsed, and 15 (41%) of the favorable responses remained durable at a median follow-up of 30 months. Myelosuppression was the major toxicity; 58% of carboplatin/Etoposide cycles were associated with hospitalization for nadir fever. The AUC of carboplatin measured in serum was lower than the target AUC; this may be related to underestimation of the glomerular filtration rate used in the dosing formula. CONCLUSION: Dose-intense therapy with sequential, accelerated chemotherapy of paclitaxel/ifosfamide and carboplatin/Etoposide administered with PBSC support was relatively well tolerated. The durable complete response proportion was substantial in patients with unfavorable prognostic features for achieving durable complete response to conventional-dose salvage programs. Optimal dosing of carboplatin in the high-dose setting warrants further investigation.

Idarubicin, high-dose cytarabine and etoposide for remission induction in therapy-related acute myeloid leukemia.[Pubmed:7858489]

Leuk Lymphoma. 1994 Sep;15(1-2):127-30.

Five patients with therapy-related acute myeloid leukemia received combination induction chemotherapy with idarubicin, high-dose cytarabine, and Etoposide. Complete remission was achieved in all patients with a single course of therapy. Treatment-related toxicity included nausea, vomiting, mucositis, diarrhea, and liver and kidney function abnormalities, and was low in all patients. There were no deaths during induction therapy. We conclude that this combination is well-tolerated in induction of remission in secondary acute myeloid leukemia, and warrants further assessment because of a very good complete remission rate.

Etoposide, doxorubicin and cisplatin plus mitotane in the treatment of advanced adrenocortical carcinoma: a large prospective phase II trial.[Pubmed:16172198]

Endocr Relat Cancer. 2005 Sep;12(3):657-66.

To investigate the activity of Etoposide, doxorubicin, and cisplatin plus mitotane in the management of advanced adrenocortical carcinoma (ACC) patients, 72 patients with measurable disease not amenable to radical surgery were enrolled in a prospective, multicenter phase II trial. EDP schedule (Etoposide 100 mg/m(2) on days 5-7, doxorubicin 20 mg/m(2) on days 1 and 8, and cisplatin 40 mg/m(2) on days 1 and 9) was administered intravenously every 4 weeks. Concomitantly, patients were given up to 4 g/day of oral mitotane. Five patients achieved a complete response and 30 a partial response, for an overall response rate of 48.6% (95% CI: 37.1-60.3). Median time to progression in responding patients was 18 months. The EDP regimen was well tolerated, leukopenia being the dose limiting toxicity. One toxic related death due to septic shock, however, was registered. Radical surgical resection of residual disease after chemotherapy was performed in 10 patients. The overall survival of patients attaining a disease free status (clinical complete responders+radically resected) was significantly higher than that of patients with partial response or no response (P<0.002). Androgen secretion was associated with long survival, while glucocorticoid secretion was associated with poor prognosis both in univariate and multivariate analysis. In conclusion, EDP plus mitotane is an active and manageable combination scheme for ACC patients. Surgical resection of residual disease subsequent to chemotherapy leads to a more favourable outcome. The natural history of the disease is significantly influenced by the secretory status of the tumor.

Topoisomerase II.etoposide interactions direct the formation of drug-induced enzyme-DNA cleavage complexes.[Pubmed:8910583]

J Biol Chem. 1996 Nov 15;271(46):29238-44.

Topoisomerase II is the target for several highly active anticancer drugs that induce cell death by enhancing enzyme-mediated DNA scission. Although these agents dramatically increase levels of nucleic acid cleavage in a site-specific fashion, little is understood regarding the mechanism by which they alter the DNA site selectivity of topoisomerase II. Therefore, a series of kinetic and binding experiments were carried out to determine the mechanistic basis by which the anticancer drug, Etoposide, enhances cleavage complex formation at 22 specific nucleic acid sequences. In general, maximal levels of DNA scission (i.e. Cmax) varied over a considerably larger range than did the apparent affinity of Etoposide (i.e. Km) for these sites, and there was no correlation between these two kinetic parameters. Furthermore, enzyme.drug binding and order of addition experiments indicated that Etoposide and topoisomerase II form a kinetically competent complex in the absence of DNA. These findings suggest that Etoposide. topoisomerase II (rather than Etoposide.DNA) interactions mediate cleavage complex formation. Finally, rates of religation at specific sites correlated inversely with Cmax values, indicating that maximal levels of Etoposide-induced scission reflect the ability of the drug to inhibit religation at specific sequences rather than the affinity of the drug for site-specific enzyme-DNA complexes.

Antitumor agents. 3. Synthesis and biological activity of 4 beta-alkyl derivatives containing hydroxy, amino, and amido groups of 4'-O-demethyl-4-desoxypodophyllotoxin as antitumor agents.[Pubmed:8389875]

J Med Chem. 1993 Jun 11;36(12):1689-99.

A series of 4 beta-alkyl (7-10), 4 beta-aminoalkyl (12a-y), and 4 beta-amidoalkyl derivatives (14a-g) of 4'-O-demethyl-4-desoxypodophyllotoxin have been synthesized, and their cytotoxicity, inhibition of DNA topoisomerase II (Topo II), and tubulin polymerization were evaluated. All derivatives of 12a-y and 14a-g did not inhibit tubulin polymerization. Many compounds exhibited cytotoxicity and inhibition of Topo II. In particular, 12o, 12s, 12t, and 12u strongly inhibited Topo II (IC50 (microM) 32.5, 60.9, 58.8, and 33.6, respectively) and were strong cytotoxicity against P388 cells (IC50 (M) 1.0, 4.1, 3.3, and 3.0 x 10(-9), respectively), compared with VP-16 (IC50 (microM) 59.2, IC50 (M) 1 x 10(-8), respectively). These compounds were nearly equal to or superior to VP-16 in antitumor activity in vivo (L1210, P388, and Lewis lung) and were more cytotoxic against various human cell lines in vitro than VP-16.

Etoposide (VP-16; VP-16-213) is an anti-cancer chemotherapy agent. Etoposide inhibits topoisomerase II, thus stopping DNA replication. Etoposide induces cell cycle arrest, apoptosis and autophagy.

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