Topo I (DU-145 Luc cells) ( IC50 = 2 nM ); Topo I (MCF-7 Luc cells) ( IC50 = 13 nM )

In a dose- and time-dependent way, topotecan strongly inhibits the growth of human glioma cells as well as glioma stem cells (GSC) [1]. Topotecan (0–40 μM) dramatically reduced cell viability in a dose-dependent manner as compared to the control group [1]. For U251, U87, GSCs-U251, and GSCs-U87 cells, topotecan has anti-proliferative action with IC50 values of 2.73±0.25, 2.95±0.23, 5.46±0.41, and 5.95±0.24 μM, in that order [1].

After receiving therapy for 14 days, all of the animals in the 4 groups in the NUB-7 transfer model were slaughtered. Animals treated with low-dose metronomic (LDM) topotecan (TP) and TP+pazopanib (PZ) had considerably lower liver weights than the control group. With the exception of TP+PZ, all mouse groups' livers displayed microtumors, demonstrating TP+PZ's capacity to prevent liver metastasis [2]. In an ovarian cancer model, topotecan (0.5, 1.0, and 1.5 mg/kg; p.o. daily) significantly decreased the density of microvessels; however, mice given 1.5 mg/kg p.o. The anti-tumor action is likewise less potent when the dosage is lowered [2].

Topotecan [(S)-9-dimethylaminomethyl-10-hydroxycamptothecin hydrochloride; SK&F 104864-A, NSC 609699], a water soluble semisynthetic analogue of the alkaloid camptothecin, is a potent topoisomerase I inhibitor. Here we show that topotecan stabilizes topoisomerase I/DNA cleavable complexes in radiation-resistant human B-lineage acute lymphoblastic leukemia (ALL) cells, causes rapid apoptotic cell death despite high-level expression of bcl-2 protein, and inhibits ALL cell in vitro clonogenic growth in a dose-dependent fashion. Furthermore, topotecan elicited potent antileukemic activity in three different severe combined immunodeficiency (SCID) mouse models of human poor prognosis ALL and markedly improved event-free survival of SCID mice challenged with otherwise fatal doses of human leukemia cells at systemic drug exposure levels that can be easily achieved in children with leukemia. [Blood. 1995 May 15;85(10):2817-28]

Gliomas, the most malignant form of brain tumors, contain a small subpopulation of glioma stem cells (GSCs) that are implicated in therapeutic resistance and tumor recurrence. Topoisomerase I inhibitors, shikonin and topotecan, play a crucial role in anti-cancer therapies. After isolated and identified the GSCs from glioma cells successfully, U251, U87, GSCs-U251 and GSCs-U87 cells were administrated with various concentrations of shikonin or topotecan at different time points to seek for the optimal administration concentration and time point. The cell viability, cell cycle and apoptosis were detected using cell counting kit-8 and flow cytometer to observe the inhibitory effects on glioma cells and GSCs. We demonstrated that shikonin and topotecan obviously inhibited proliferation of not only human glioma cells but also GSCs in a dose- and time-dependent manner. According to the IC50 values at 24 h, 2 μmol/L of shikonin and 3 μmol/L of topotecan were selected as the optimal administration concentration. In addition, shikonin and topotecan induced cell cycle arrest in G0/G1 and S phases and promoted apoptosis. The down-regulation of Bcl-2 expression with the activation of caspase 9/3-dependent pathway was involved in the apoptosis process. Therefore, the above results showed that topoisomerase I inhibitors, shikonin and topotecan, inhibited growth and induced apoptosis of GSCs as well as glioma cells, which suggested that they might be the potential anticancer agents targeting gliomas to provide a novel therapeutic strategy[1].

In vivo antitumor efficacies of the LDM topotecan and pazopanib as single agents and in combination were tested on 4 subcutaneous xenograft models and on 2 neuroblastoma metastatic models. Circulating angiogenic factors such as circulating endothelial cells (CEC), circulating endothelial pro genitor cells (CEP), and microvessel densities were used as surrogate biomarker markers of antiangiogenic activity.[2]

Absorption, Distribution and Excretion
Renal clearance is an important determinant of topotecan elimination. In a mass balance/excretion study in 4 patients with solid tumors, the overall recovery of total topotecan and its N-desmethyl metabolite in urine and feces over 9 days averaged 73.4 ± 2.3% of the administered IV dose. Fecal elimination of total topotecan accounted for 9 ± 3.6% while fecal elimination of N-desmethyl topotecan was 1.7 ± 0.6%.
The pharmacokinetics of topotecan have been extensively studied in patients with normal renal function and there is one study of patients with mild to moderate renal insufficiency. However, the effect of hemodialysis on topotecan disposition has not been reported. The objective of this study was to characterize the disposition of topotecan in a patient with severe renal insufficiency receiving hemodialysis. Topotecan lactone disposition was characterized in a patient on and off hemodialysis. The topotecan lactone clearance determined after administration of topotecan alone and with hemodialysis was 5.3 L/hr per sq m vs 20.1 L/hr per sq m respectively. At 30 min after the completion of hemodialysis, the topotecan plasma concentration obtained was greater than that measured at the end of hemodialysis (i.e. 8.0 ng/mL vs 4.9 ng/mL), suggesting a rebound effect. The topotecan terminal half-life off dialysis was 13.6 hr, compared with an apparent half-life determined during hemodialysis of 3.0 hr. These results demonstrate that topotecan plasma clearance while on hemodialysis increased approximately fourfold. Hemodialysis may be an effective systemic clearance process for topotecan and should be considered in selected clinical situations (e.g. inadvertent overdose, severe renal dysfunction).
In lactating rats receiving IV topotecan at a dosage of 4.72 mg/sq m, high concentrations of the drug (i.e., up to 48 times higher than plasma concentrations) were distributed into milk. It is not known whether topotecan is distributed into human milk.
Following oral administration, about 57% of topotecan (administered daily for 5 days) is excreted in urine as unchanged drug (20%) and as the N-desmethyl metabolite (2%).47 Approximately 33% of the oral dose of topotecan was eliminated in feces as total topotecan and approximately 2% as N-desmethyl topotecan. Following IV administration, about 74% of a topotecan dose is excreted, mostly unchanged in urine (51%) and feces (18%) within 9 days; excretion of N-desmethyl topotecan in urine is approximately 3% and in feces is approximately 2%. O-Glucuronide metabolites of topotecan and N-desmethyl topotecan also have been detected in urine following oral and IV (less than 2% of the administered IV dose) administration of the drug.
No substantial gender-related differences in pharmacokinetics were reported in patients receiving oral topotecan. The average plasma clearance of IV topotecan was 24% higher in males than in females, mainly because of difference in body size.
For more Absorption, Distribution and Excretion (Complete) data for Topotecan (6 total), please visit the HSDB record page.

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Metabolism / Metabolites
Topotecan undergoes a reversible pH dependent hydrolysis of its lactone moiety; it is the lactone form that is pharmacologically active.
Topotecan undergoes a reversible pH-dependent hydrolysis of its lactone moiety; it is the lactone form that is pharmacologically active. At pH =4, the lactone is exclusively present, whereas the ring-opened hydroxy-acid form predominates at physiologic pH. In vitro studies in human liver microsomes indicate topotecan is metabolized to an N-demethylated metabolite. The mean metabolite:parent AUC ratio was about 3% for total topotecan and topotecan lactone following IV administration.

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Biological Half-Life
2-3 hours
The pharmacokinetics of topotecan have been evaluated in cancer patients following doses of 0.5 to 1.5 mg/sq m administered as a 30-minute infusion. Topotecan exhibits multiexponential pharmacokinetics with a terminal half-life of 2 to 3 hours.
Topotecan has a terminal half-life of 3-6 hours following oral administration and 2-3 hours following IV administration of the drug.
... The objective of this study was to characterize the disposition of topotecan in a patient with severe renal insufficiency receiving hemodialysis. ... The topotecan terminal half-life off dialysis was 13.6 hr, compared with an apparent half-life determined during hemodialysis of 3.0 hr. ...

Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Most sources consider breastfeeding to be contraindicated during maternal high-dose antineoplastic drug therapy. The manufacturer recommends that women not breastfeed during treatment with topotecan and for 1 week after the last dose. Chemotherapy may adversely affect the normal microbiome and chemical makeup of breastmilk. Women who receive chemotherapy during pregnancy are more likely to have difficulty nursing their infant.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
35%

[1]. PLoS One. 2013 Nov 26;8(11):e81815.Topoisomerase I inhibitors, Shikonin and Topotecan, inhibit growth and induce apoptosis of glioma cells andglioma stem cells.

[2]. Metronomic oral topotecan with pazopanib is an active antiangiogenic regimen in mouse models of aggressive pediatric solid tumor. Clin Cancer Res. 2011 Sep 1;17(17):5656-67.

Topotecan is a pyranoindolizinoquinoline used as an antineoplastic agent. It is a derivative of camptothecin and works by binding to the topoisomerase I-DNA complex and preventing religation of these 328 single strand breaks. It has a role as an EC 5.99.1.2 (DNA topoisomerase) inhibitor and an antineoplastic agent.
An antineoplastic agent used to treat ovarian cancer. It works by inhibiting DNA topoisomerases, type I.
Topotecan is a Topoisomerase Inhibitor. The mechanism of action of topotecan is as a Topoisomerase Inhibitor.
Topotecan is a semisynthetic derivative of camptothecin, a cytotoxic, quinoline-based alkaloid extracted from the Asian tree Camptotheca acuminata. Topotecan inhibits topoisomerase I activity by stabilizing the topoisomerase I-DNA covalent complexes during S phase of cell cycle, thereby inhibiting religation of topoisomerase I-mediated single-strand DNA breaks and producing potentially lethal double-strand DNA breaks when encountered by the DNA replication machinery.
An antineoplastic agent used to treat ovarian cancer. It works by inhibiting DNA TOPOISOMERASES, TYPE I.
See also: Topotecan Hydrochloride (has salt form); Topotecan Hydrochloride (1:1.25) (is active moiety of).

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Drug Indication
For the treatment of advanced ovarian cancer in patients with disease that has recurred or progressed following therapy with platinum-based regimens. Also used as a second-line therapy for treatment-sensitive small cell lung cancer, as well as in combination with cisplatin for the treatment of stage IV-B, recurrent, or persistent cervical cancer not amenable to curative treatment with surgery and/or radiation therapy.
FDA Label
Hycamtin capsules are indicated as monotherapy for the treatment of adult patients with relapsed small cell lung cancer (SCLC) for whom re-treatment with the first-line regimen is not considered appropriate. Topotecan is indicated for the treatment of patients with metastatic carcinoma of the ovary after failure of first-line or subsequent therapy. Hycamtin capsules are indicated as monotherapy for the treatment of adult patients with relapsed small cell lung cancer (SCLC) for whom re-treatment with the first-line regimen is not considered appropriate.
Topotecan monotherapy is indicated for the treatment of: - patients with metastatic carcinoma of the ovary after failure of first-line or subsequent therapy- patients with relapsed small cell lung cancer (SCLC) for whom re-treatment with the first-line regimen is not considered appropriate (see section 5. 1). Topotecan in combination with cisplatin is indicated for patients with carcinoma of the cervix recurrent after radiotherapy and for patients with Stage IVB disease. Patients with prior exposure to cisplatin require a sustained treatment free interval to justify treatment with the combination (see section 5. 1).
Topotecan monotherapy is indicated for the treatment of patients with relapsed small-cell lung cancer (SCLC) for whom re-treatment with the first-line regimen is not considered appropriate. , , Topotecan in combination with cisplatin is indicated for patients with carcinoma of the cervix recurrent after radiotherapy and for patients with stage IVB disease. Patients with prior exposure to cisplatin require a sustained treatment-free interval to justify treatment with the combination. ,
Topotecan monotherapy is indicated for the treatment of patients with relapsed small cell lung cancer [SCLC] for whom re-treatment with the first-line regimen is not considered appropriate. , , Topotecan in combination with cisplatin is indicated for patients with carcinoma of the cervix recurrent after radiotherapy and for patients with Stage IVB disease. Patients with prior exposure to cisplatin require a sustained treatment free interval to justify treatment with the combination. ,
Topotecan monotherapy is indicated for the treatment of: , , , patients with metastatic carcinoma of the ovary after failure of first line or subsequent therapy; , patients with relapsed small cell lung cancer [SCLC] for whom re-treatment with the first-line regimen is not considered appropriate. , , , Topotecan in combination with cisplatin is indicated for patients with carcinoma of the cervix recurrent after radiotherapy and for patients with Stage IVB disease. Patients with prior exposure to cisplatin require a sustained treatment free interval to justify treatment with the combination. ,
Topotecan monotherapy is indicated for the treatment of patients with relapsed small cell lung cancer (SCLC) for whom re-treatment with the first-line regimen is not considered appropriate. Topotecan in combination with cisplatin is indicated for patients with carcinoma of the cervix recurrent after radiotherapy and for patients with Stage IVB disease. Patients with prior exposure to cisplatin require a sustained treatment free interval to justify treatment with the combination.
Topotecan is indicated for the treatment of patients with metastatic carcinoma of the ovary after failure of first-line or subsequent therapy.

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Mechanism of Action
Topotecan has the same mechanism of action as irinotecan and is believed to exert its cytotoxic effects during the S-phase of DNA synthesis. Topoisomerase I relieves torsional strain in DNA by inducing reversible single strand breaks. Topotecan binds to the topoisomerase I-DNA complex and prevents religation of these single strand breaks. This ternary complex interferes with the moving replication fork, which leads to the induction of replication arrest and lethal double-stranded breaks in DNA. As mammalian cells cannot efficiently repair these double strand breaks, the formation of this ternary complex eventually leads to apoptosis (programmed cell death). Topotecan mimics a DNA base pair and binds at the site of DNA cleavage by intercalating between the upstream (−1) and downstream (+1) base pairs. Intercalation displaces the downstream DNA, thus preventing religation of the cleaved strand. By specifically binding to the enzyme–substrate complex, Topotecan acts as an uncompetitive inhibitor.
Topoisomerase I relieves torsional strain in DNA by inducing reversible single-strand breaks. Topotecan binds to the topoisomerase I-DNA complex and prevents religation of these single-strand breaks. The cytotoxicity of topotecan is thought to be due to double-strand DNA damage produced during DNA synthesis, when replication enzymes interact with the ternary complex formed by topotecan, topoisomerase I, and DNA. Mammalian cells cannot efficiently repair these double strand breaks.

C23H23N3O5

421.453

421.163

C, 65.55; H, 5.50; N, 9.97; O, 18.98

123948-87-8

Topotecan hydrochloride;119413-54-6; Topotecan hydrochloride hydrate;1044663-62-8; Topotecan-d6;1044904-10-0; 123948-87-8

60700

Typically exists as solid at room temperature

1.5±0.1 g/cm3

782.9±60.0 °C at 760 mmHg

−114 °C(lit.)

427.3±32.9 °C

0.0±2.8 mmHg at 25°C

1.734

1.08

2

7

3

31

867

1

O=C1[C@](O)(CC)C2=C(CO1)C(N3CC4=CC5=C(CN(C)C)C(O)=CC=C5N=C4C3=C2)=O

UCFGDBYHRUNTLO-QHCPKHFHSA-N

InChI=1S/C23H23N3O5/c1-4-23(30)16-8-18-20-12(9-26(18)21(28)15(16)11-31-22(23)29)7-13-14(10-25(2)3)19(27)6-5-17(13)24-20/h5-8,27,30H,4,9-11H2,1-3H3/t23-/m0/s1

(19S)-8-[(dimethylamino)methyl]-19-ethyl-7,19-dihydroxy-17-oxa-3,13-diazapentacyclo[11.8.0.02,11.04,9.015,20]henicosa-1(21),2,4(9),5,7,10,15(20)-heptaene-14,18-dione

NSC 609699; NSC-609699; NSC609699; SKF S104864A; SKF 104864 A; SKF-104864-A; SKF104864A; TOPO. Hycamtamine; Topotecan lactone; Hycamptamine; Hycamptin; (S)-Topotecan; Topotecane; Topotecanum; Nogitecan; Topotecan

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)