β-tubulin; microtubule

PlinabuLin (NPI-2358), a potent antineoplastic agent, rapidly induces tubulin depolymerization and monolayer permeability in multidrug-resistant (MDR) tumor cell lines. In HUVEC, the IC50 values are 18 nM for DU 145 cells, 13 nM for PC-3 cells, 14 nM for MDA-MB-231 cells, 18 nM for NCI-H292 cells, and 11 for Jurkat leukemia cells. nM[1].

Tumor perfusion is reduced in a dose- and time-dependent manner in female CDF1 and C3H/He mice when given plinabuLin (0 mg/kg–15 mg/kg; intraperitoneally). Plinabulin's anticancer effects are more responsive to KHT sarcomas than they are to C3H tumors, and both models exhibit an increased radiation response [3].

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Thirty-eight patients were enrolled. A dose of 30 mg/m² was selected as the RP2D based on the adverse events of nausea, vomiting, fatigue, fever, tumor pain, and transient blood pressure elevations, with DCE-MRI indicating decreases in tumor blood flow (Ktrans) from 13.5 mg/m² (defining a biologically effective dose) with a 16% to 82% decrease in patients evaluated at 30 mg/m². Half-life was 6.06 ± 3.03 hours, clearance was 30.50 ± 22.88 L/h, and distributive volume was 211 ± 67.9 L. Conclusions: At the RP2D of 30 mg/m², plinabulin showed a favorable safety profile, while eliciting biological effects as evidenced by decreases in tumor blood flow, tumor pain, and other mechanistically relevant adverse events. On the basis of these results additional clinical trials were initiated with plinabulin in combination with standard chemotherapy agents.[2]

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Plinabulin (7.5 mg/kg) significantly reduced the initial area under curve (IAUC) and the transfer constant (K(trans)) within 1 hour after injection, reaching a nadir at 3 h, but returning to normal within 24 h. A dose-dependent decrease in IAUC and K(trans), was seen at 3 h. No significant anti-tumour effects were observed in the C3H tumours until doses of 12.5 mg/kg were achieved, but started at 1.5 mg/kg in the KHT sarcoma. Irradiating tumours 1 h after injecting plinabulin enhanced response in both models. Conclusions: Plinabulin induced a time- and dose-dependent decrease in tumour perfusion. The KHT sarcoma was more sensitive than the C3H tumour to the anti-tumour effects of plinabulin, while radiation response was enhanced in both models.[3]

The diketopiperazine NPI-2358 is a synthetic analog of NPI-2350, a natural product isolated from Aspergillus sp., which depolymerizes microtubules in A549 human lung carcinoma cells. Although structurally different from the colchicine-binding site agents reported to date, NPI-2358 binds to the colchicine-binding site of tubulin. NPI-2358 has potent in-vitro anti-tumor activity against various human tumor cell lines and maintains activity against tumor cell lines with various multidrug-resistant (MDR) profiles. In addition, when evaluated in proliferating human umbilical vein endothelial cells (HUVECs), concentrations as low as 10 nmol/l NPI-2358 induced tubulin depolymerization within 30 min. Furthermore, NPI-2358 dose dependently increases HUVEC monolayer permeability--an in-vitro model of tumor vascular collapse. NPI-2358 was compared with three tubulin-depolymerizing agents with vascular-disrupting activity: colchicine, vincristine and combretastatin A-4 (CA4). Results showed that the activity of NPI-2358 in HUVECs was more potent than either colchicine or vincristine; the profile of CA4 approached that of NPI-2358. Altogether, our data show that NPI-2358 is a potent anti-tumor agent which is active in MDR tumor cell lines, and is able to rapidly induce tubulin depolymerization and monolayer permeability in HUVECs. These data warrant further evaluation of NPI-2358 as a vascular-disrupting agent in vivo. Currently, NPI-2358 is in preclinical development for the treatment of cancer. [1]

Cell Viability Assay[1]
Cell Types: HUVECs cells
Tested Concentrations: 2 nM, 10 nM, 20 nM and 200 nM
Incubation Duration: 30 minutes
Experimental Results: Low concentrations (2 nM, 10 nM) rapidly induced tubulin depolymerization in HUVECs.

Animal/Disease Models: Female CDF1 mice (10-14weeks old) with C3H mammary carcinoma; Female C3H/HeJ mice with KHT sarcoma cells (8-weeks-old)[3]
Doses: 0 mg/kg, 1.5 mg/kg , 2.5 mg/kg, 5 mg/kg, 7.5 mg/kg, 10 mg/kg, 12.5 mg/kg, 15 mg/kg; 0.02 mL/g mouse body weight in CDF1 mice and 0.01 mL/g body weight for C3H /HeJ mice
Route of Administration: intraperitoneal (ip)injection; 0 huor, 1 huor, 3 hrs (hours), 6 huors, 24 huors
Experimental Results: Induced a time- and dose-dependent decrease in tumour perfusion. The KHT sarcoma was more sensitive than the C3H tumour to the anti -tumor, while radiation response was enhanced in both models.

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Patients received a weekly infusion of plinabulin for 3 of every 4 weeks. A dynamic accelerated dose titration method was used to escalate the dose from 2 mg/m² to the RP2D, followed by enrollment of an RP2D cohort. Safety, pharmacokinetic, and cardiovascular assessments were conducted, and Dynamic contrast-enhanced MRI (DCE-MRI) scans were performed to estimate changes in tumor blood flow.[2]

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Foot implanted C3H mammary carcinomas or leg implanted KHT sarcomas were used, with plinabulin injected intraperitoneally. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) measurements were made with gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) on a 7-tesla magnet. Treatment response was assessed using regrowth delay (C3H tumours), clonogenic survival (KHT sarcomas) or histological estimates of necrosis for both models.[3]

[1]. NPI-2358 is a tubulin-depolymerizing agent: in-vitro evidence for activity as a tumor vascular-disrupting agent. Anticancer Drugs. 2006 Jan;17(1):25-31.

[2]. Phase 1 First-in-Human Trial of the Vascular Disrupting Agent Plinabulin (NPI-2358) in Patients with Solid Tumors or Lymphomas Clin Cancer Res. 2010 Dec 1;16(23):5892-9.

[3]. Vascular effects of plinabulin (NPI-2358) and the influence on tumour response when given alone or combined with radiation. Int J Radiat Biol. 2011 Nov;87(11):1126-34.

Plinabulin is a member of the class of 2,5-diketopiperazines that is piperazine-2,5-dione substituted by benzylidene and (5-tert-butyl-1H-imidazol-4-yl)methylidene groups at positions 3 and 6, respectively. It is a vascular disrupting agent and a microtubule destabalising agent which was in clinical trials (now discontinued) for the treatment of non-small cell lung cancer. It has a role as a microtubule-destabilising agent, an antineoplastic agent, an apoptosis inducer and an angiogenesis inhibitor. It is a member of 2,5-diketopiperazines, a member of imidazoles, a member of benzenes and an olefinic compound.
Plinabulin is an orally active diketopiperazine derivative with potential antineoplastic activity. Plinabulin selectively targets and binds to the colchicine-binding site of tubulin, thereby interrupting equilibrium of microtubule dynamics. This disrupts mitotic spindle assembly leading to cell cycle arrest at M phase and blockage of cell division. In addition, plinabulin may also inhibit growth of proliferating vascular endothelial cells, thereby disrupting the function of tumor vasculature that further contributes to a decrease in tumor cell proliferation.

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Drug Indication
Investigated for use/treatment in cancer/tumors (unspecified).

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Mechanism of Action
NPI-2358 is a vascular disrupting agent currently in clinical development for the treatment of cancer by Nereus. NPI-2358 is one of over 200 synthetic analogues that were prepared following the discovery of the compound Halimide isolated from a marine fungus. In preclinical models of cancer, including lung, breast, sarcoma, colon and prostate, NPI-2358 demonstrated potent and selective anti-tumor effects in combination with docetaxel and other oncology therapies, as well as single-agent efficacy in a number of orthotopic models. NPI-2358 interacts with soluble beta-tubulin and prevents the polymerization of tubulin without altering dynamic microtubule function of formed microtubules. As demonstrated in preclinical testing, this target profile results in a highly specific nanomolar cytotoxicity while reducing the side effects seen in first-generation VDAs due to cardiotoxicity, hemodynamic changes and neuropathies.

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Plinabulin (NPI-2358) is a vascular disrupting agent that elicits tumor vascular endothelial architectural destabilization leading to selective collapse of established tumor vasculature. Preclinical data indicated plinabulin has favorable safety and antitumor activity profiles, leading to initiation of this clinical trial to determine the recommended phase 2 dose (RP2D) and assess the safety, pharmacokinetics, and biologic activity of plinabulin in patients with advanced malignancies. [2]

C19H20N4O2

336.39

336.158

C, 67.84; H, 5.99; N, 16.66; O, 9.51

714272-27-2

9949641

Light yellow to yellow solid powder

1.3±0.1 g/cm3

730.3±60.0 °C at 760 mmHg

395.5±32.9 °C

0.0±2.4 mmHg at 25°C

1.657

2.66

3

3

3

25

597

0

CC(C)(C)C1=C(N=CN1)/C=C\2/C(=O)N/C(=C\C3=CC=CC=C3)/C(=O)N2

UNRCMCRRFYFGFX-TYPNBTCFSA-N

InChI=1S/C19H20N4O2/c1-19(2,3)16-13(20-11-21-16)10-15-18(25)22-14(17(24)23-15)9-12-7-5-4-6-8-12/h4-11H,1-3H3,(H,20,21)(H,22,25)(H,23,24)/b14-9-,15-10-

(3E,6E)-3-benzylidene-6-((5-(tert-butyl)-1H-imidazol-4-yl)methylene)piperazine-2,5-dione

NPI-2358; Plinabulin; NPI2358; Plinabulin(NPI-2358); NPI 2358; NPI-2358 (Plinabulin); (3z,6z)-3-Benzylidene-6-[(5-Tert-Butyl-1h-Imidazol-4-Yl)methylidene]piperazine-2,5-Dione; 986FY7F8XR; NPI 2358;

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 (7.43 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 (7.43 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 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 (7.43 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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 (Please use freshly prepared in vivo formulations for optimal results.)