Bcl-W (Ki=1 nM); Bcl-xL (Ki=1 nM); Bcl-2 (Ki=1 nM)

The Bcl-2/Bcl-xL interactions with pro-apoptotic proteins are disrupted by ABT-263, which is structurally related to ABT-737. The maintenance, progression, and chemoresistance of tumors are frequently linked to overexpression of prosurvival Bcl-2 family members. ABT-263 exhibits the defense provided by overexpression of Bcl-2 or Bcl-xL with EC50 values of 60 nM and 20 nM, respectively. ABT-263 inhibits 50% of growth in the most sensitive line (H146) with an EC50 of 110 nM, whereas the least sensitive line (H82) exhibits a wide range of cellular activity with an EC50 of 22 M. The two most resistant cell lines (H1048 and H82) are also similarly resistant to ABT-263, as are all four cell lines (H146, H889, H1963, and H1417) with EC50 values of less than 400 nM.

In the H345 xenograft model, significant antitumor efficacy is seen with 80% TGI and 20% of treated tumors indicating at least a 50% reduction in tumor volume. In xenograft models of small-cell lung cancer and acute lymphoblastic leukemia, oral administration of ABT-263 alone results in total tumor regressions. ABT-263 significantly improves the efficacy of clinically pertinent therapeutic regimens in xenograft models of aggressive B-cell lymphoma and multiple myeloma, where it exhibits modest or no single agent activity.

---

ABT-263 induced significant prolongation of the EFS distribution in 9 of 35 (26%) of the solid tumor xenografts, and in 5 of 6 (83%) of the evaluable ALL xenografts. ABT-263 induced no objective responses in the solid tumor panels, but induced CRs in 3 of 6 evaluable xenografts in the ALL panel, including two that were maintained for an additional 3 weeks following treatment cessation.[1]

---

Navitoclax enhances the activity of docetaxel in vivo[3]
As shown in Fig. 1B, docetaxel exhibited positive combination activities with navitoclax in a high percentage of cancer cell lines (78%). Docetaxel represents a clinically relevant anti-microtubule agent approved for use in a variety of tumors. To extend these observations to in vivo, navitoclax was tested in combination with docetaxel in the SKOV3 ovarian cancer xenograft model using a variety of different schedules (Fig. 2). As a monotherapy, navitoclax dosed orally once a day at 100 mg/kg for 2, 14, or 21 days was not efficacious in the SKOV3 xenograft model (Fig. 2). Docetaxel administered once weekly for 3 cycles at 10 mg/kg/d produced a significant decrease in tumor burden (TGI) of 82% with a delay in regrowth (TGD) of 114% (Table 2). In contrast, bolus dosing of docetaxel dosed 30 mg/kg once intravenously inhibited tumor growth by only 48% with no significant effect on time to progression. ORRs were slightly higher when cyclical dosing was administered, rather than bolus dosing (30% vs. 0%).

Binding affinities (Ki or IC50) of ABT-263 against different isoforms of Bcl-2 family are determined with competitive fluorescence polarization assays. The following peptide probe/protein pairs are used: f-bad (1 nM) and Bcl-xL (6 nM), f-Bax (1 nM) and Bcl-2 (10 nM), f-Bax (1 nM) and Bcl-w (40 nM), f-Noxa (2 nM) and Mcl-1 (40 nM), and f-Bax (1 nM) and Bcl-2-A1 (15 nM). Binding affinities for Bcl-xL are also determined using a time-resolved fluorescence resonance energy transfer assay. Bcl-xL (1 nM, His tagged) is mixed with 200 nM f-Bak, 1 nM Tb-labeled anti-His antibody, and ABT-263 at room temperature for 30 min. Fluorescence is measured on an Envision plate reader using a 340/35 nm excitation filter and 520/525 (f-Bak) and 495/510 nm (Tb-labeled anti-His antibody) emission filters.

Human tumor cell lines SCLC cell lines are maintained at 37℃ containing 5% CO2. SCLC cell lines are cultured in RPMI 1640 with 10% fetal bovine serum (FBS), 1% sodium pyruvate, 25 mM HEPES, 4.5 g/L glucose, and 1% penicillin/streptomycin. Leukemia and lymphoma cell lines are cultured in RPMI 1640 supplemented with 10% FBS and 1% penicillin/streptomycin. Cells (1-5×10 4) are treated by ABT-263 for 48 hours in 96-well culture plates in a final volume of 100 μL and cytotoxicity is assessed with the CellTiter Glo assay. In vitro cyto toxicity of ABT-263 is assayed.

ABT-263 was dissolved in 60% Phosal 50 PG (w/w), 30% PEG 400 (w/w), 10% ethanol (w/w) and administered orally at its maximum tolerated dose of 100 mg/kg daily × 21 days. ABT-263 was provided to each consortium investigator in coded vials for blinded testing, according to the PPTP's standard operating procedures. CB17SC-M scid−/− female mice were used to propagate subcutaneously implanted kidney/rhabdoid tumors, sarcomas (Ewing, osteosarcoma, rhabdomyosarcoma), neuroblastoma, and non-glioblastoma brain tumors, while BALB/c nu/nu mice were used for glioma models. Human leukemia cells were propagated by intravenous inoculation in female non-obese diabetic (NOD)/scid−/− mice as described previously. [1]

---

All studies used 6 to 10 mice per group. Statistical comparisons of tumor growth rate and TGD used the Wilcoxon rank-sum test and the Mantel–Cox log-rank test, respectively. Navitoclax was formulated in 10% ethanol, 30% polyethylene glycol 400, and 60% Phosal 50 PG (a dispersion of 50% phosphatidylcholine in a propylene glycol/ethanol carrier) and administered orally by gavage. [3]

---

100 mg/kg/day

Formulated in 10% ethanol, 30% polyethylene glycol 400, and 60% Phosal 50 PG

C.B -17 scid-bg or C.B -17 scid mice

[1]. Initial testing (stage 1) of the BH3 mimetic ABT-263 by the pediatric preclinical testing program. Pediatr Blood Cancer. 2008 Jun;50(6):1181-1189.

[2]. Navitoclax (ABT-263) reduces Bcl-x(L)-mediated chemoresistance in ovarian cancer models.Mol Cancer Ther. 2012 Apr;11(4):1026-1035.

[3]. The Bcl-2/Bcl-X(L)/Bcl-w inhibitor, navitoclax, enhances the activity of chemotherapeutic agents in vitro and in vivo. Mol Cancer Ther. 2011 Dec;10(12):2340-9.

Navitoclax is a N-sulfonylcarboxamide resulting from the formal condensation of the carboxy group of 4-{4-[(4'-chloro-4,4-dimethyl-3,4,5,6-tetrahydro[biphenyl]-2-yl)methyl]piperazin-1-yl}benzoic acid with the amino group of 4-{[(2R)-4-(morpholin-4-yl)-1-(phenylsulfanyl)butan-2-yl]amino}-3-[(trifluoromethyl)sulfonyl]benzenesulfonamide. It is a BH3-mimetic drug which targets the anti-apoptotic B-cell lymphoma-2 (BCL-2) family proteins, including BCL-2, BCL-xL, and BCL-w, and induces apoptosis in cancer cells. Currently under clinical investigation as treatment for solid tumors and hematologic malignancies. It has a role as a B-cell lymphoma 2 inhibitor, an apoptosis inducer and an antineoplastic agent. It is a member of piperazines, a member of monochlorobenzenes, a member of morpholines, an aryl sulfide, a N-sulfonylcarboxamide, a sulfone, an organofluorine compound, a secondary amino compound and a tertiary amino compound.
Navitoclax has been used in trials studying the treatment and basic science of Solid Tumors, Non-Hodgkin's Lymphoma, EGFR Activating Mutation, Chronic Lymphoid Leukemia, and Hematological Malignancies, among others. Navitoclax is an orally bioavailable small molecule inhibitor of Bcl-2 family proteins. It is a substance being studied in the treatment of lymphomas and other types of cancer. It blocks some of the enzymes that keep cancer cells from dying.
Navitoclax is an orally active, synthetic small molecule and an antagonist of a subset of the B-cell leukemia 2 (Bcl-2) family of proteins with potential antineoplastic activity. Navitoclax selectively binds to apoptosis suppressor proteins Bcl-2, Bcl-XL, and Bcl-w, which are frequently overexpressed in a wide variety of cancers, including those of the lymph, breast, lung, prostate, and colon, and are linked to tumor drug resistance. Inhibition of these apoptosis suppressors prevents their binding to the apoptotic effectors Bax and Bak proteins, thereby triggering apoptotic processes in cells overexpressing Bcl-2, Bcl-XL, and Bcl-w. This eventually reduces tumor cell proliferation.

---

Drug Indication
Treatment of myelofibrosis

---

Mechanism of Action
Navitoclax targets the Bcl-2 family of proteins, the major negative regulators of apoptosis. The Bcl-2 proteins, including Bcl-2, Bcl-xL, and Bcl-w, work by binding to two other groups of proteins-the executioners (Bax, Bak) that actually start the destruction pathway, and the sentinel proteins. Cancer cells frequently overexpress the Bcl-2-like proteins, and thus, when they sustain DNA damage-from radiation, for example-they continue growing. Preventing the Bcl-2-like proteins from binding to the executioners might be able to trigger cell death in the tumor.

C47H55CLF3N5O6S3

974.61

973.295

C, 57.92; H, 5.69; Cl, 3.64; F, 5.85; N, 7.19; O, 9.85; S, 9.87

923564-51-6

Navitoclax-d8;1217620-38-6; 923564-51-6; 2143096-93-7 (Navitoclax-piperazine); 1093851-28-5 (HCl)

24978538

White to light yellow solid powder

1.4±0.1 g/cm3

114-116ºC

1.655

12.14

2

14

16

65

1800

1

C(N1CCN(C2C=CC(C(=O)NS(C3C=CC(N[C@@H](CSC4C=CC=CC=4)CCN4CCOCC4)=C(S(=O)(=O)C(F)(F)F)C=3)(=O)=O)=CC=2)CC1)C1CC(C)(C)CCC=1C1C=CC(Cl)=CC=1

JLYAXFNOILIKPP-KXQOOQHDSA-N

InChI=1S/C47H55ClF3N5O6S3/c1-46(2)20-18-42(34-8-12-37(48)13-9-34)36(31-46)32-55-22-24-56(25-23-55)39-14-10-35(11-15-39)45(57)53-65(60,61)41-16-17-43(44(30-41)64(58,59)47(49,50)51)52-38(19-21-54-26-28-62-29-27-54)33-63-40-6-4-3-5-7-40/h3-17,30,38,52H,18-29,31-33H2,1-2H3,(H,53,57)/t38-/m1/s1

(R)-4-(4-((4'-chloro-4,4-dimethyl-3,4,5,6-tetrahydro-[1,1'-biphenyl]-2-yl)methyl)piperazin-1-yl)-N-((4-((4-morpholino-1-(phenylthio)butan-2-yl)amino)-3-((trifluoromethyl)sulfonyl)phenyl)sulfonyl)benzamide

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: 2.08 mg/mL (2.13 mM) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), suspension solution; with sonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 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: 2.08 mg/mL (2.13 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 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: ≥ 2.08 mg/mL (2.13 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 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

---

Solubility in Formulation 4: 55% DMSO+Corn oil: 8mg/mL

---

Solubility in Formulation 5: 7.5 mg/mL (7.70 mM) in 60% phosal 50 propylene glycol (PG), 30% polyethylene glycol 400 (PEG400), 10% ethanol (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.

---

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