β-tubulin (colchicine binding site). No IC50, Ki, EC50, or DC50 values for target binding are provided in this paper. [1]

In vitro, ABT-751 shows the selective cytotoxicity with IC50 of 0.6–2.6 μM in neuroblastoma and 0.7–4.6 μM in other solid tumor cell lines. Furthermore, ABT-751 also exhibits a selective effect on dynamic microtubules and spares stable microtubules, accounting for the persistence of acetylated and detyrosinated α-tubulin positive polymerized tubules at the IC90 concentration of ABT-751.

---

Kinase Assay: ABT-751(E 7010) is a novel bioavailable tubulin-binding and antimitotic sulfonamide agent with IC50 of about 1.5 and 3.4 μM in neuroblastoma and non-neuroblastoma cell lines, respectively.

---

Cell Assay: Cells (HOS, HTB-186 Daoy, TC-71, RD, SK-N-AS, SK-N-DZ, LD and KCNR cells), in 1640 RPMI media with FBS, are plated in triplicate onto 96 well tissue culture plates in numbers determined optimal for confluent monolayer growth (5,000 cells/well for HOS, HTB-186 Daoy; 10,000 cells/well for TC-71, RD, SK-N-AS, SK-N-DZ, LD; 30,000 cells/well for KCNR), with an automated, multichannel pipette system. Cells are incubated for 24 hours at 37 °C/5% CO2 then exposed to vehicle control (1.25% DMSO/H2O), VCR (0.1–1000 nM), ABT-751 (0.1 nM–100 μM), and in 4 cell lines (SK-N-AS, KCNR, RD, TC-71) combretastatin (0.1–1000 nM) for 72 hours. Cells are fixed with trichloroacetic acid (final concentration 10%) at 4 °C, washed, then dried at room temperature, stained with SRB in 1% acetic acid and dye is then solubilized with Tris base. Optical density measurements are performed at 540 and 405 nm dual wavelengths in a Bio-Tek EL 340 UV plate reader.

---

In vitro cytotoxicity: ABT-751 was cytotoxic in all 8 pediatric tumor cell lines (neuroblastoma SK-N-AS, SK-N-DZ, KCNR; rhabdomyosarcoma RD; Ewing sarcoma TC-71, LD; medulloblastoma HTB-186 Daoy; osteosarcoma HOS) with IC50 values ranging from 0.6 to 4.6 mM (determined by SRB and ACEA RT-CES assays). The mean IC50 for ABT-751 in three neuroblastoma cell lines was 0.93 mM (SRB assay) vs. 1.8 mM in five non-neuroblastoma lines. Vincristine was more potent (IC50 1.2-8.8 nM) but clinically tolerated dose of ABT-751 is ~250 times higher. [1]
Tubulin polymerization assay (Western blot): In all 8 cell lines, ABT-751 caused a concentration- and time-dependent decrease in stable polymerized tubulin as detected by antibodies specific for post-translational modifications (detyrosinated and acetylated α-tubulin). At equipotent (IC50, IC90) concentrations, the degree of decrease was less extensive with ABT-751 compared to vincristine or combretastatin. [1]
Confocal microscopy: ABT-751 induced a concentration-dependent decrease in stable polymerized tubulin. At IC90, a distinctive microtubule pattern with coarse, thick, curled microtubules remained, whereas vincristine and combretastatin caused near-complete loss of polymerized tubulin. The anti-tyrosinated α-tubulin antibody showed granular appearance of tubulin with increasing ABT-751 concentrations, consistent with depolymerization. [1]

In this Calu-6 xenograft model, ABT-751 as a single agent at 100 and 75 mg/kg/day shows significant antitumor activity, while in combination with cisplatin, ABT-751 shows a dose-dependent enhancement in growth delay. In the HT-29 colon xenograft model, ABT-751 also shows significant antitumor activity as a single agent and produced a dose-dependent enhancement in growth delay In combination with 5-FU. In dogs with lymphoma, ABT-751 exhibits the dose-limiting toxicities that included vomiting, diarrhea, anorexia, or some combination of these with a maximum tolerated dose (MTD) of 350 mg/m2 PO q24h. Furthermore, the mean AUC and Cmax for ABT-751 at the MTD of 350 mg/m2 is 5.55 μg-hour/mL and 0.9 μg/mL, respectively.
In vivo clinical activity in pediatric patients: 50 neuroblastoma patients (heavily pretreated, 78% had prior high-dose chemotherapy/radiotherapy with autologous HSCT, 88% had biologic therapy) received ABT-751 on phase I and pilot trials (7-day schedule: 200 mg/m²/day for 7 days every 21 days; or 21-day schedule). No complete or partial responses were documented. Median event-free survival (EFS) was 9.3 weeks for neuroblastoma patients (n=50) vs. 3.3 weeks for other solid tumors (n=26) (P<0.0001). Median progression-free survival for neuroblastoma was 11.7 weeks; median overall survival was 62.5 weeks. Six patients (13%) completed study or continued without progression; three completed 50 cycles (150 weeks). Prolonged disease stabilization was observed. [1]
Pharmacodynamic effect in patients: In 10 neuroblastoma patients, PBMC samples showed a decrease in polymerized tubulin (by anti-detyrosinated α-tubulin antibody) following ABT-751 administration in some patients, but no consistent pattern. Anti-acetylated α-tubulin was not detectable. [1]

Cell viability/cytotoxicity assays: (1) Sulforhodamine B (SRB) assay: Cells were plated in 96-well plates at optimal densities (5,000-30,000 cells/well) in RPMI with FBS, incubated 24h, then exposed to vehicle control (1.25% DMSO/H2O), ABT-751 (0.1 mM - 100 mM), vincristine (0.1-1000 nM), or combretastatin (0.1-1000 nM) for 72h. Cells were fixed with trichloroacetic acid (10% final), washed, dried, stained with SRB in 1% acetic acid, dye solubilized with Tris base, and optical density measured at 540/405 nm. Survival = (mean OD drug-exposed / mean OD vehicle control) × 100. [1]
(2) ACEA RT-CES real-time cell electronic sensing assay: Cells were plated on 16-well E-plates with embedded microelectrodes. Hourly measurements of electrical impedance (Cell Index) were taken for 96h (plating through 72h drug exposure). Survival = (mean CI drug-exposed / mean CI vehicle control) × 100. The method generated continuous growth curves; at low non-cytotoxic concentrations of ABT-751, Cell Index increased up to 50% in some lines (e.g., SK-N-AS, TC-71), presumably due to drug-related alteration in cell size/morphology. [1]
Tubulin polymerization assay (Western blot): Cells were plated on 100 mm dishes (500,000-3,000,000 cells/dish), incubated 24h, then exposed to vehicle, ABT-751, vincristine, or combretastatin for 72h at IC10, IC50, IC90 concentrations. Cells were scraped, pelleted, resuspended in lysis buffer (0.1 M PIPES, 1 mM EGTA, 1 mM MgSO4, 30% glycerol, 5% DMSO, 0.125% IGEPAL, protease inhibitor, aprotinin, 5 mM GTP), vortexed, centrifuged. Supernatant protein concentration standardized by Bradford assay. Samples (15 mg total protein) separated by SDS-PAGE, transferred to PVDF, probed with anti-detyrosinated α-tubulin, anti-acetylated α-tubulin, anti-tyrosinated α-tubulin, and anti-α-tubulin antibodies. Chemiluminescent detection. In some experiments, lysis buffer contained 5 mM paclitaxel. [1]
Confocal microscopy: Cells were plated on 12 mm glass coverslips, incubated 24h, exposed to drugs for 72h at IC10, IC50, IC90. Fixed with cold methanol (-20°C), blocked with 5% BSA in PBS, then exposed to primary antibodies (anti-detyrosinated, anti-acetylated, anti-tyrosinated, anti-α-tubulin), followed by FITC-labeled secondary antibodies. Coverslips mounted with Fluor-Gel. Intracellular microtubule structure observed on confocal microscope (Axiovert 100M with LSM510). [1]

Dissolved in 4% ethanol/96% dextrose solution (D5W) with 1 eq. 1 N HCl; 75 or 100 mg/kg; P.O. Calu-6 NSCLC, HT-29 colon, and HCT-116 cells are injected into athymic mice.

---

Pharmacokinetics in pediatric patients: At the recommended dose of 200 mg/m²/day administered orally once daily for 7 days every 21 days, the mean peak plasma concentration (Cmax) was 46 mcM (micromolar) and the mean steady-state concentration (Css) was 10 mcM. ABT-751 is orally bioavailable. [1]

Toxicities observed in neuroblastoma patients (phase I and pilot study): Dose-limiting toxicities included grade 2 decrease in left ventricular function (asymptomatic decrease in left ventricular shortening fraction); grade 3 thrombocytopenia, neutropenia, neuropathic pain, dehydration, and fatigue; grade 4 elevated ALT and weight loss. One patient experienced encephalopathy (severe adverse event) – this patient had no CNS disease but had received TBI and neck irradiation 4 years prior. ABT-751 is not significantly myelosuppressive at the recommended dose (200 mg/m²/day for 7 days in children). [1]

Pediatr Blood Cancer.2010 Jan;54(1):47-54;Cancer Chemother Pharmacol.2007 May;59(6):725-32.

N-[2-(4-hydroxyaniline)-3-pyridyl]-4-methoxybenzenesulfonamide is a sulfonamide drug. ABT-751 has been investigated for the treatment of lung cancer, including non-small cell lung cancer (NSCLC). ABT-751, a colchicine-binding site binder, is an orally bioavailable antimitotic sulfonamide drug. ABT-751 binds to the colchicine binding site on β-tubulin, inhibiting microtubule polymerization and thus preventing tumor cell replication. This drug also disrupts tumor angiogenesis, reducing tumor blood flow and thus producing cytotoxic effects. (NCI04)

---

ABT-751 is a synthetic tubulin-binding agent with favorable pharmacological properties: oral bioavailability, not a substrate for P-glycoprotein-mediated multidrug resistance, binds to a distinct site on β-tubulin (colchicine site) different from vinca alkaloid and taxane sites. It demonstrated prolonged disease stabilization and event-free survival in a heavily pretreated neuroblastoma population. Health-related quality of life (PedsQL) during treatment was not significantly changed from baseline; clinician-assigned performance status was weakly to moderately correlated with patient-reported QOL (r=0.40, p=0.08). A Children's Oncology Group phase 2 study of ABT-751 in relapsed/refractory neuroblastoma is evaluating progression-free survival and quality of life. [1]

C18H17N3O4S

371.41

371.093

141430-65-1

141430-65-1;857447-92-8 141450-48-8 (HCl);

3035714

White to off-white solid powder

1.4±0.1 g/cm3

551.0±60.0 °C at 760 mmHg

162 °C(dec.)

287.0±32.9 °C

0.0±1.5 mmHg at 25°C

1.677

4.58

3

7

6

26

523

0

URCVCIZFVQDVPM-UHFFFAOYSA-N

InChI=1S/C18H17N3O4S/c1-25-15-8-10-16(11-9-15)26(23,24)21-17-3-2-12-19-18(17)20-13-4-6-14(22)7-5-13/h2-12,21-22H,1H3,(H,19,20)

N-[2-(4-hydroxyanilino)pyridin-3-yl]-4-methoxybenzenesulfonamide

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 (6.73 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.

---

Solubility in Formulation 2: ≥ 2.5 mg/mL (6.73 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.

---

View More

Solubility in Formulation 3: 30% Propylene glycol , 5% Tween 80 , 65% D5W:15 mg/mL

---

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