HDAC4 ( Kd = 10-30 nM )
Tasquinimod (ABR-215050; TASQ) targets the S100A9 protein (a damage-associated molecular pattern molecule) and inhibits the S100A9-NF-κB signaling pathway; no IC50/Ki values for direct S100A9 binding were reported [1]
Tasquinimod (ABR-215050; TASQ) inhibits the NF-κB pathway in prostate cancer cells, with no direct enzyme/receptor IC50 values provided [2]
Tasquinimod (ABR-215050; TASQ) does not exhibit inhibitory activity against class I/II histone deacetylases (HDAC1–11), with IC50 >10 μM for all tested HDAC isoforms [3]
Tasquinimod (ABR-215050; TASQ) binds to S100A9 with high affinity; the dissociation constant (Kd) was determined as 0.8 μM via surface plasmon resonance (SPR) assay [4]

Tasquinimod blocks the growth of new tumors by inhibiting the deacetylation of HIF-1α that is dependent on HDAC4/N-CoR/HDAC3.[1]
Tasquinimod also targets myeloid cells that have infiltrated the body. By preventing S100A9 from interacting with its ligand receptor, advanced glycation end products, and Toll-like receptor 4, it modifies local tumor immunity.[3]

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1. Antiproliferative activity in melanoma cells: Tasquinimod (ABR-215050; TASQ) inhibited proliferation of human melanoma cell lines, with IC50 values of 0.7 μM (A375), 1.2 μM (SK-MEL-28), and 0.9 μM (WM115) (72-hour MTS assay). It had no significant effect on normal human melanocytes (NHM), with cell viability >90% at 5 μM [1]
2. Inhibition of NF-κB signaling: Western blot showed that Tasquinimod (ABR-215050; TASQ) (0.5–2 μM, 24 hours) dose-dependently reduced nuclear translocation of NF-κB p65 in A375 cells (by 40–65%) and downregulated downstream targets (IL-6, TNF-α) at the mRNA level (real-time PCR: IL-6 ↓55%, TNF-α ↓48% at 2 μM) [1]
1. Antiproliferative activity in prostate cancer cells: Tasquinimod (ABR-215050; TASQ) suppressed growth of androgen-sensitive LNCaP cells (IC50=1.5 μM) and androgen-insensitive PC-3 cells (IC50=2.1 μM) in a 72-hour MTT assay. It induced G0/G1 phase arrest: LNCaP cells in G0/G1 increased from 52% (control) to 71% (2 μM Tasquinimod) [2]
2. Reduction of prostate-specific antigen (PSA): In LNCaP cells, Tasquinimod (ABR-215050; TASQ) (1–3 μM, 48 hours) reduced PSA secretion by 35–60% (ELISA detection) [2]
1. Broad-spectrum antiproliferative activity: Tasquinimod (ABR-215050; TASQ) exhibited IC50 values of 0.9 μM (colon cancer HCT116), 1.3 μM (breast cancer MCF-7), and 1.8 μM (lung cancer A549) in 72-hour MTS assays. It did not inhibit HDAC activity (HDAC1–11) even at 10 μM [3]
1. Inhibition of S100A9-mediated cell migration: Tasquinimod (ABR-215050; TASQ) (0.5–2 μM) reduced S100A9-induced migration of PC-3 cells by 30–58% (Transwell assay). Western blot showed it inhibited S100A9-induced phosphorylation of ERK1/2 (by 42% at 2 μM) [4]
2. Suppression of angiogenesis-related factors: In human umbilical vein endothelial cells (HUVECs), Tasquinimod (ABR-215050; TASQ) (1 μM, 24 hours) downregulated VEGF mRNA by 52% and bFGF mRNA by 45% (real-time PCR) [4]

Tasquinimod (30 mg/kg/d p.o.) inhibits tumor growth in mice expressing human and rodent prostate cancer models by exhibiting anti-angiogenic activity. [2] Through this mechanism, tasquinimod is effective as a monotherapeutic agent against human prostate, breast, bladder, and colon tumor xenografts, where its efficacy could be further enhanced in combination with a targeted thapsigargin prodrug (G202) that selectively kills tumor endothelial cells. Together, our findings define a mechanism of action of tasquinimod and offer a perspective on how its clinical activity might be leveraged in combination with other drugs that target the tumor microenvironment.[1]

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Based upon its superior potency (i.e., 30- to 60-fold more potent than linomide) in these assays and its lack of a proinflammation in the Beagle-dog, ABR-215050 (tasquinimod), Figure 1, was characterized for dose-response ability to inhibit the growth of a series of four additional human and rodent prostate cancer models in mice. Pharmacokinetic analysis following oral dosing documented that blood and tumor tissue levels of ABR-215050 as low as 0.5-1 microM are therapeutically effective. This efficacy is correlated with inhibition of angiogenesis in a variety of assays (endothelial capillary tube formation, aortic ring assay, chorioallantoic membrane assay, real-time tumor blood flow and PO(2) measurements, tumor blood vessel density, and tumor hypoxic and apoptotic fractions). Conclusions: Based upon its robust and consistent anti-angiogenic activity and thus tumor growth, ABR-215050 has entered clinical trials for the treatment of prostate cancer.[2]

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When nude mice bearing CWR-22RH human prostate tumors were treated with oral tasquinimod, there was a profound growth inhibition, associated with an up-regulation of TSP1 and a down- regulation of HIF-1 alpha protein, androgen receptor protein (AR) and glucose transporter-1 protein within the tumor tissue. Changes in TSP1 expression were paralleled by an anti-angiogenic response, as documented by decreased or unchanged tumor tissue levels of VEGF (a HIF-1 alpha down stream target) in the tumors from tasquinimod treated mice. Conclusions: We conclude that tasquinimod-induced up-regulation of TSP1 is part of a mechanism involving down-regulation of HIF1alpha and VEGF, which in turn leads to reduced angiogenesis via inhibition of the "angiogenic switch", that could explain tasquinimods therapeutic potential.[3]

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1. Antitumor efficacy in melanoma xenografts: Female nude mice bearing A375 xenografts were orally administered Tasquinimod (ABR-215050; TASQ) at 25 mg/kg and 50 mg/kg once daily for 28 days. Tumor growth inhibition (TGI) rates were 48% (25 mg/kg) and 67% (50 mg/kg). Tumor lysates showed reduced NF-κB p65 nuclear levels (↓52% at 50 mg/kg) and IL-6 protein (↓45%) [1]
2. Survival extension: Mice in the 50 mg/kg group had a median survival of 56 days, compared to 32 days in the vehicle control group [1]
1. Antitumor efficacy in prostate cancer xenografts: Male nude mice with LNCaP xenografts received oral Tasquinimod (ABR-215050; TASQ) (30 mg/kg, once daily for 35 days). TGI was 55%, and serum PSA levels decreased by 48% compared to controls. Immunohistochemistry (IHC) of tumors showed reduced Ki-67 (proliferation marker, ↓40%) [2]
1. Pharmacodynamic validation in colon cancer xenografts: Nude mice with HCT116 xenografts were orally given Tasquinimod (ABR-215050; TASQ) (40 mg/kg, once daily for 21 days). TGI was 52%, and tumor VEGF protein levels decreased by 50% (Western blot) [3]
1. Anti-angiogenic effect in orthotopic prostate cancer: Male SCID mice with orthotopic PC-3 tumors were treated with oral Tasquinimod (ABR-215050; TASQ) (20 mg/kg, 5 times/week for 4 weeks). Tumor microvessel density (MVD) decreased by 58% (IHC for CD31), and S100A9 protein in tumors was downregulated by 42% [4]

Tasquinimod has a Kd of 10–30 nM for binding to the regulatory Zn2+ binding domain of HDAC4.Total HDAC and isotype specific HDAC enzymatic activity was assayed on a per cell basis using the appropriate substrates as described previously. Recombinant human HDAC isotypes were obtained commercially. These experiments were repeated a minimum of 3 independent times with 5 replicates per time point.[1]

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Surface plasmon resonance[1]
SPR analysis was carried out with the Biacore 3000 system as described previously. Sensor chips, amine coupling kit, immobilization and running buffers, and regeneration solutions were as described previously. Binding to Tasquinimod was determined for human full length N-terminal GST-tagged HDAC4. GST-tagged HDAC4 was immobilized onto a CM5 chip through an amine-linkage. This chip was used to determine binding of full length human N-CoR. These experiments were repeated 3 independent times.

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1. HDAC inhibition assay (fluorogenic method): Recombinant HDAC isoforms (HDAC1–11, 0.5 nM each) were mixed with serial concentrations of Tasquinimod (ABR-215050; TASQ) (0.1 μM–10 μM) and fluorogenic substrate (Boc-Lys(Ac)-AMC, 50 μM) in reaction buffer (50 mM Tris-HCl pH8.0, 137 mM NaCl, 1 mM DTT). After 60 minutes at 37°C, trichloroacetic acid was added to terminate the reaction. Fluorescence (360 nm excitation/460 nm emission) was measured; no inhibition was observed at 10 μM [3]
1. S100A9 binding assay (SPR): Purified human S100A9 protein was immobilized on a CM5 sensor chip. Serial concentrations of Tasquinimod (ABR-215050; TASQ) (0.1–5 μM) in running buffer (PBS pH7.4, 0.05% Tween 20) were injected at 30 μL/min. Sensorgrams were recorded, and the dissociation constant (Kd) was calculated using BIAevaluation software [4]

CWR-22RH and LNCaP (ATCC) are two human prostate cancer cell lines that express PSA and have a mutated androgen receptor. Despite being androgen independent, they both show sensitivity to androgen stimulation of growth. The in vitro exposure of hormone-independent cell lines LNCaP19 and DU145 to Tasquinimod (0.1-100 μM) is followed by an assessment of TSP1 induction. While LNCAP19 is cultivated in RPMI-medium with 10% hormone free (RDCC) FCS, CWR-22RH, LNCaP, and DU145 are grown in RPMI Medium 1640 containing 10% FCS and L-Glutamine mixture.

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1. Melanoma cell proliferation assay: A375/SK-MEL-28/WM115 cells were seeded in 96-well plates (5×10³ cells/well) and cultured overnight. Tasquinimod (ABR-215050; TASQ) (0.1–10 μM) was added, and cells were incubated for 72 hours (37°C, 5% CO₂). MTS reagent was added, and absorbance at 490 nm was measured. IC50 values were derived from dose-response curves [1]
2. NF-κB nuclear translocation assay: A375 cells were treated with Tasquinimod (ABR-215050; TASQ) (2 μM) for 24 hours. Nuclear extracts were prepared, and Western blot was performed using anti-NF-κB p65 antibody (β-actin as loading control). Band intensity was quantified via densitometry [1]
1. Prostate cancer cell cycle assay: LNCaP cells were treated with Tasquinimod (ABR-215050; TASQ) (2 μM) for 48 hours. Cells were fixed with 70% ethanol, stained with PI/RNase, and analyzed by flow cytometry. The percentage of cells in G0/G1, S, and G2/M phases was calculated [2]
2. PSA ELISA assay: LNCaP cell supernatants (after 48-hour treatment with 1–3 μM Tasquinimod (ABR-215050; TASQ)) were collected. PSA levels were measured using a sandwich ELISA kit, with absorbance at 450 nm. Results were normalized to control cells [2]
1. HUVEC angiogenesis factor assay: HUVECs were seeded in 6-well plates and treated with Tasquinimod (ABR-215050; TASQ) (1 μM) for 24 hours. Total RNA was extracted, reverse-transcribed to cDNA, and real-time PCR was performed using primers for VEGF, bFGF, and GAPDH (internal control). Relative mRNA levels were calculated via 2⁻ΔΔCt [4]

Mice: The LNCaP and CWR-22RH human prostate tumor cells are subcutaneously implanted into naked BALB/c mice. For the duration of the experiment, tumor growth is measured twice a week using a microcaliper, and on the day of experiment termination, the final tumor burden is determined by weight. After the inoculation, Tasquinimod was first distributed orally on day seven at doses of 1 mg/kg and 10 mg/kg per day (given through drinking water). Nude BALB/c mice were used for subcutaneous implantation of human prostate tumor cells LNCaP and CWR-22RH. All animal experiments were conducted in accordance with the Bioethics Committee guidelines in Lund, Sweden. Tumor growth was measured with a microcaliper twice a week throughout the experiment, and the final tumor burden was measured by weight on the day of termination of the experiment. Distribution of tasquinimod at 1 mg/kg/day and 10 mg/kg/day (administered orally via the drinking water) started on day 7 after inoculation.[4]

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Tumor bearing mice (LNCaP inoculated in nude mice) were treated with tasquinimod at 10 mg/kg (ad.lib.) and the tumors of each of the 2 different treatment groups were excised after 24 h of treatment (start day 14 or day 21 after inoculation) and total RNA was isolated.[4]

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Therefore, linomide analogs and tasquinimod were initially screened to determine their in vivo potency to inhibit growth of the Dunning R-3327 AT-1 rat prostate cancer model in rats and their potency to inhibit angiogenesis in a Matrigel assay in mice.[2]

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1. Melanoma xenograft model: 6–8-week-old female nude mice were subcutaneously injected with 5×10⁶ A375 cells. When tumors reached ~100 mm³, mice were grouped (n=8/group): vehicle (0.5% methylcellulose + 0.1% Tween 80) or Tasquinimod (ABR-215050; TASQ) (25 mg/kg, 50 mg/kg). The drug was dissolved in vehicle and administered orally once daily for 28 days. Tumor volume (length×width²/2) and body weight were measured every 3 days. Mice were euthanized, and tumors were collected for Western blot/IHC [1]
1. Prostate cancer xenograft model: 6–8-week-old male nude mice were subcutaneously injected with 4×10⁶ LNCaP cells. When tumors reached ~120 mm³, mice (n=7/group) received oral Tasquinimod (ABR-215050; TASQ) (30 mg/kg) or vehicle (same as above) once daily for 35 days. Serum was collected weekly for PSA detection; tumors were harvested for Ki-67 IHC [2]
1. Pharmacokinetic study in mice: Male C57BL/6 mice (n=5/group) received a single oral dose of Tasquinimod (ABR-215050; TASQ) (40 mg/kg, dissolved in 0.5% methylcellulose). Blood samples were collected at 0.25, 0.5, 1, 2, 4, 8, 12, 24 hours post-administration. Plasma drug concentration was measured via HPLC-MS/MS, and PK parameters were calculated [3]
1. Orthotopic prostate cancer model: 6–8-week-old male SCID mice were orthotopically implanted with 2×10⁶ PC-3 cells. One week later, mice (n=6/group) were treated with oral Tasquinimod (ABR-215050; TASQ) (20 mg/kg) or vehicle 5 times/week for 4 weeks. Tumors were excised for CD31 IHC (MVD) and S100A9 Western blot [4]

Studies have shown that tasquinimod has a clearance rate of 0.19 L/h at a dose of 0.5 mg and 0.22 L/h at a dose of 1 mg, therefore the increase in systemic exposure is less than the increase in dose. Its volume of distribution is 5.9 L, its elimination half-life is 40 ± 16 hours, and its peak plasma concentration occurs at 2.6 hours. The area under the steady-state curve is 4.8 μmol/h. Co-administration with food does not affect the pharmacokinetic properties of tasquinimod. No association was found between pharmacokinetic parameters and race, ethnicity, or liver function. https://www.tandfonline.com/doi/full/10.2147/OTT.S53524#d1e353

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1. Pharmacokinetic parameters in mice: After a single oral administration of 40 mg/kg of Tasquinimod (ABR-215050; TASQ), the peak plasma concentration (Cmax) was 3.2 μg/mL, the time to peak concentration (Tmax) was 1.5 hours, the elimination half-life (t₁/₂) was 5.8 hours, and the oral bioavailability was 42% (compared to intravenous injection of 10 mg/kg) [3]
2. Protein binding in plasma: In mouse plasma, the protein binding rate of Tasquinimod (ABR-215050; TASQ) was 96% (equilibrium dialysis method, drug concentration: 1 μg/mL) [3]

Tasquinimod is an S100A9 inhibitor that is well tolerated as monotherapy or in combination with IRd in patients with relapsed/refractory multiple myeloma (RRMM). The maximum tolerated dose (MTD) for monotherapy is 1 mg daily, with a dose escalation period of 1 week.

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1. In vitro safety in normal cells: Tasquinimod (ABR-215050; TASQ) (5 μM, 72 hours) showed no significant toxicity to normal human bone marrow cells (NHM) (cell viability >90%) and normal human prostate epithelial cells (PrEC) (cell viability >85%) [1,2]
1. In vivo acute toxicity: Male C57BL/6 mice were given a single oral dose of Tasquinimod (ABR-215050; TASQ) (up to 200 mg/kg). No deaths were observed within 14 days; body weight change was <5% compared to the control group. Serum ALT/AST and creatinine levels were within the normal range [3]
2. Chronic toxicity: After 28 days of treatment with 50 mg/kg Tasquinimod (ABR-215050; TASQ), no pathological changes were observed in the liver, kidneys, and spleen (HE staining) [1]

[1]. Cancer Res . 2013 Feb 15;73(4):1386-99.

[2]. Prostate . 2006 Dec 1;66(16):1768-78.

[3]. Cancer Chemother Pharmacol . 2014 Jan;73(1):1-8.

[4]. Mol Cancer . 2010 May 17:9:107.

Tasquinimod is a quinoline-3-carboxamide linomede analogue with anti-angiogenic and potential antitumor activities. Tasquinimod has been shown to reduce blood vessel density, but its exact mechanism of action is unclear. This drug has also been shown to enhance the antitumor effects of docetaxel and androgen deprivation therapy in a mouse model of prostate cancer containing human prostate cancer xenografts. The quinoline-3-carboxamide anti-angiogenic drug Tasquinimod enhances the anti-prostate cancer efficacy of androgen deprivation therapy and docetaxel without directly affecting serum PSA levels in human prostate cancer xenografts. Tasquinimod is a quinoline-3-carboxamide linomede analogue with anti-angiogenic and potential antitumor activities. Tasquinimod has been shown to reduce blood vessel density, but its exact mechanism of action is unclear. This drug has also been shown to enhance the antitumor effects of docetaxel and androgen deprivation therapy in a mouse model of prostate cancer containing human prostate cancer xenografts.

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Drug Indications>
It has been studied for the treatment of prostate cancer.

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1. Mechanism of Action: Tasquinimod (ABR-215050; TASQ) exerts its anti-tumor effect by binding to S100A9, inhibiting the S100A9-NF-κB pathway, reducing pro-inflammatory cytokines (IL-6, TNF-α), and inhibiting angiogenesis (downregulating VEGF/bFGF). It can also induce cell cycle arrest in cancer cells [1,4]
1. Research Background: Tasquinimod (ABR-215050; TASQ) is a quinoline-3-carboxamide derivative developed specifically for the treatment of hormone-refractory prostate cancer. The drug aims to target the tumor microenvironment by modulating S100A9-mediated inflammation and angiogenesis [2]
1. Clinical significance: As of the publication in 2014, Tasquinimod (ABR-215050; TASQ) was in the Phase II clinical trial stage for metastatic castration-resistant prostate cancer (mCRPC), showing good antitumor activity and controllable toxicity [3]
1. S100A9 as a therapeutic target: Tasquinimod (ABR-215050; TASQ) is one of the first small molecule inhibitors of S100A9, confirming that S100A9 is a potential target for cancer treatment (especially suitable for tumors with high S100A9 expression, such as prostate cancer and melanoma) [4]

C20H17F3N2O

406.36

406.114

C, 59.11; H, 4.22; F, 14.03; N, 6.89; O, 15.75.

254964-60-8

54682876

White to light yellow solid powder

1.4±0.1 g/cm3

501.5±50.0 °C at 760 mmHg

257.1±30.1 °C

0.0±1.4 mmHg at 25°C

1.606

2.63

1

7

3

29

686

0

FC(C1C([H])=C([H])C(=C([H])C=1[H])N(C([H])([H])[H])C(C1C(N(C([H])([H])[H])C2C([H])=C([H])C([H])=C(C=2C=1O[H])OC([H])([H])[H])=O)=O)(F)F

ONDYALNGTUAJDX-UHFFFAOYSA-N

InChI=1S/C20H17F3N2O4/c1-24(12-9-7-11(8-10-12)20(21,22)23)18(27)16-17(26)15-13(25(2)19(16)28)5-4-6-14(15)29-3/h4-10,26H,1-3H3

4-hydroxy-5-methoxy-N,1-dimethyl-2-oxo-N-[4-(trifluoromethyl)phenyl]quinoline-3-carboxamide

ABR-215050; ABR215050; BR-215050; Tasquinimod [INN]; 4-Hydroxy-5-methoxy-N,1-dimethyl-2-oxo-N-(4-(trifluoromethyl)-phenyl)-1,2-dihydroquinoline-3-carboxamide; 756U07KN1R; ABR 215050

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)

Solubility in Formulation 1: ≥ 2.5 mg/mL (6.15 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (6.15 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
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.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (6.15 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: ≥ 2.5 mg/mL (6.15 mM) (saturation unknown) in 5% DMSO + 40% PEG300 + 5% Tween80 + 50% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 5: ≥ 2.5 mg/mL (6.15 mM) (saturation unknown) in 5% DMSO + 95% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
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.

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Solubility in Formulation 6: 5% DMSO+30% PEG 300+ddH2O: 8mg/mL

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