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 a crucial determinant of topotecan elimination. In a mass balance/excretion study of four patients with solid tumors, the mean recovery of total topotecan and its N-demethyl metabolites in urine and feces over 9 days was 73.4 ± 2.3% of the intravenously administered dose. The fecal excretion rate of total topotecan was 9 ± 3.6%, while that of N-demethyltopotecan was 1.7 ± 0.6%. The pharmacokinetics of topotecan have been extensively studied in patients with normal renal function, and one study was conducted in patients with mild to moderate renal impairment. However, the effect of hemodialysis on the distribution of topotecan in the body has not been reported. This study aimed to describe the distribution of topotecan in patients with severe renal impairment undergoing hemodialysis. The distribution of topotecan lactone in a patient undergoing hemodialysis and a patient not undergoing hemodialysis was characterized. The clearance rates of topotecanolactone, measured when used alone and in combination with hemodialysis, were 5.3 L/hr/m² and 20.1 L/hr/m², respectively. Thirty minutes after the end of hemodialysis, the plasma concentration of topotecan was higher than that at the end of dialysis (i.e., 8.0 ng/mL vs. 4.9 ng/mL), suggesting a rebound effect. The terminal half-life of topotecan was 13.6 hours when not undergoing hemodialysis, while the apparent half-life measured during hemodialysis was 3.0 hours. These results indicate that the plasma clearance of topotecan increased approximately fourfold during hemodialysis. Hemodialysis may be an effective method for systemic clearance of topotecan and should be considered in specific clinical situations (e.g., accidental overdose, severe renal impairment). In lactating rats receiving intravenous topotecan (at a dose of 4.72 mg/m²), drug concentrations were high (i.e., 48 times higher than plasma concentrations) and distributed into breast milk. It is currently unclear whether topotecan is distributed into human breast milk. Following oral administration, approximately 57% of topotecan (once daily for 5 consecutive days) is excreted in the urine as unchanged drug (20%) and N-desmethyl metabolite (2%). Approximately 33% of the oral topotecan is excreted in the feces as total topotecan, and approximately 2% as N-desmethyltopotecan. Following intravenous administration, approximately 74% of the topotecan dose is excreted within 9 days, primarily as unchanged drug in the urine (51%) and feces (18%); approximately 3% of N-desmethyltopotecan is excreted in the urine and approximately 2% in the feces. Following oral and intravenous administration (intravenous dose less than 2% of the administered dose), topotecan and the O-glucuronide metabolite of N-desmethyltopotecan were also detected in the urine.
No significant sex-based pharmacokinetic differences were reported in patients receiving oral topotecan. The mean plasma clearance of topotecan via intravenous administration was 24% higher in men than in women, primarily due to body size differences.
For more complete data on absorption, distribution, and excretion of topotecan (6 items in total), please visit the HSDB record page.

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Metabolism/Metabolites
The lactone moiety of topotecan undergoes reversible pH-dependent hydrolysis; the lactone form of topotecan is pharmacologically active.
The lactone moiety of topotecan undergoes reversible pH-dependent hydrolysis; the lactone form is the pharmacologically active form. At pH=4, the lactone form is predominant, while under physiological pH conditions, the open-ring hydroxy acid form is predominant. In vitro human liver microsomal studies indicate that topotecan is metabolized to an N-demethylated metabolite. After intravenous administration, the mean AUC ratio of total topotecan and topotecan lactone metabolites to the parent drug is approximately 3%.

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Biological Half-Life
2-3 hours
The pharmacokinetics of topotecan have been evaluated in cancer patients at doses of 0.5 to 1.5 mg/m², administered via intravenous infusion over 30 minutes. Topotecan exhibits multi-exponential decay pharmacokinetics with a terminal half-life of 2 to 3 hours. The terminal half-life of oral topotecan is 3 to 6 hours, while that after intravenous administration is 2 to 3 hours. …This study aimed to describe the distribution of topotecan in patients with severe renal impairment undergoing hemodialysis. …After dialysis, the terminal half-life of topotecan was 13.6 hours, compared to an apparent half-life of 3.0 hours measured during dialysis. …

Effects During Pregnancy and Lactation
◉ Overview of Lactation Use
Most data suggest that breastfeeding is not advisable while the mother is receiving high-dose anti-tumor drug treatment. The manufacturer recommends that women not breastfeed during topotecan treatment and for one week after the last dose. Chemotherapy may adversely affect the normal microbiota and chemical composition of breast milk. Women receiving chemotherapy during pregnancy are more likely to experience breastfeeding difficulties. ◉ Effects on Breastfed Infants
No published information found as of the revision date. ◉ Effects on Lactation and Breast Milk
No published information found as of the revision date.

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Protein Binding Rate
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 pyranoindoquinoline antitumor drug. It is a derivative of camptothecin and works by binding to the topoisomerase I-DNA complex, preventing the rejoining of 328 single-strand breaks. It is an EC 5.99.1.2 (DNA topoisomerase) inhibitor and an antitumor drug. It is an antitumor drug used to treat ovarian cancer. Its mechanism of action is through the inhibition of type I DNA topoisomerase. Topotecan is a topoisomerase inhibitor. The mechanism of action of topotecan is as a topoisomerase inhibitor. Topotecan is a semi-synthetic derivative of camptothecin, a cytotoxic quinoline alkaloid extracted from the Asian tree Camptotheca acuminata. Topotecan inhibits the activity of topoisomerase I by stabilizing the topoisomerase I-DNA covalent complex during the S phase of the cell cycle, thereby inhibiting the rejoining of topoisomerase I-mediated single-strand DNA breaks and generating potentially lethal double-strand DNA breaks when these breaks are encountered in DNA replication.
An antitumor drug used to treat ovarian cancer. Its mechanism of action is the inhibition of type I DNA topoisomerase.
See also: Topotecan hydrochloride (salt form); Topotecan hydrochloride (1:1.25) (its active ingredient).
Indications

For the treatment of patients with advanced ovarian cancer who have relapsed or progressed after platinum-based chemotherapy. Also used as second-line therapy for treatment-sensitive small cell lung cancer, and in combination with cisplatin for the treatment of stage IV-B, recurrent or persistent cervical cancer that is not suitable for surgical and/or radiotherapy.
FDA Label
Hycamtin capsules are indicated for monotherapy in adult patients with recurrent small cell lung cancer (SCLC) who are not eligible for further first-line therapy. Topotecan is indicated for the treatment of patients with metastatic ovarian cancer who have failed first-line or subsequent therapy. Hycamin capsules are indicated for the treatment of adult patients with recurrent small cell lung cancer (SCLC) who are not eligible for further first-line therapy. Topotecan monotherapy is indicated for: - Patients with ovarian metastatic cancer who have failed first-line or subsequent treatment; - Patients with recurrent small cell lung cancer (SCLC) who are not suitable for further first-line treatment (see Section 5.1). Topotecan in combination with cisplatin is indicated for patients with recurrent cervical cancer after radiotherapy and patients with stage IVB cervical cancer. Patients who have previously received cisplatin treatment require a long treatment-free interval before receiving combination therapy (see Section 5.1). Topotecan monotherapy is indicated for patients with recurrent small cell lung cancer (SCLC) who are not suitable for further first-line treatment. Topotecan in combination with cisplatin is indicated for patients with recurrent cervical cancer after radiotherapy and patients with stage IVB cervical cancer. Patients who have previously received cisplatin treatment require a long treatment-free interval before receiving combination therapy. Topotecan monotherapy is indicated for patients with recurrent small cell lung cancer (SCLC) who are not suitable for further first-line treatment. Topotecan in combination with cisplatin is indicated for patients with recurrent cervical cancer after radiotherapy and patients with stage IVB cervical cancer. Patients who have previously received cisplatin therapy require a long treatment-free period before receiving combination therapy. Topotecan monotherapy is suitable for: patients with metastatic ovarian cancer who have failed first-line or subsequent therapy; and for patients with recurrent small cell lung cancer (SCLC) who are not suitable for further first-line therapy. Topotecan in combination with cisplatin is also feasible for patients with cervical cancer that has recurred after radiotherapy and for patients with stage IVB cervical cancer. Patients who have previously received cisplatin therapy require a long treatment-free period before receiving combination therapy. Patients who have previously received cisplatin therapy require a long treatment-free period before receiving combination therapy.
Topotecan is suitable for patients with metastatic ovarian cancer who have failed first-line or subsequent therapy.

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Mechanism of Action
Topotecan's mechanism of action is the same as irinotecan, and it is believed to exert cytotoxic effects during the S phase of DNA synthesis. Topoisomerase I relieves DNA torsional stress by inducing reversible single-strand breaks. Topotecan binds to the topoisomerase I-DNA complex, preventing the rejoining of these single-strand breaks. This ternary complex interferes with the movement of the replication fork, leading to replication arrest and fatal double-strand breaks in DNA. Since mammalian cells cannot effectively repair these double-strand breaks, the formation of this ternary complex ultimately leads to apoptosis (programmed cell death). Topotecan mimics DNA base pairs, binding to DNA break sites by inserting between upstream (-1) and downstream (+1) base pairs. This insertion displaces downstream DNA, preventing the rejoining of the broken strand. Topotecan acts as a non-competitive inhibitor by specifically binding to the enzyme-substrate complex. Topoisomerase I alleviates DNA torsional stress by inducing reversible single-strand breaks. Topotecan binds to the topoisomerase I-DNA complex, preventing the rejoining of these single-strand breaks. The cytotoxicity of topotecan is thought to be caused by double-strand DNA damage during DNA synthesis, where the replicase interacts with the ternary complex formed by topotecan, topoisomerase I, and DNA. Mammalian cells cannot effectively 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.)