Polymeric Tubulysin-Peptide Nanoparticles with Potent Antitumor Activity

IT-101, a cyclodextrin polymer-based nanoparticle containing camptothecin, is in clinical development for the treatment of cancer. Multiorgan pharmacokinetics and accumulation in tumor tissue of IT-101 is investigated by using PET. IT-101 is modified through the attachment of a 1,4,7,10-tetraazacyclododecane-1,4,7-Tris-acetic acid ligand to bind 64 Cu 2؉ . This modification does not affect the particle size and minimally affects the surface charge of the resulting nanoparticles. PET data from 64 Cu-labeled IT-101 are used to quantify the in vivo biodistribution in mice bearing Neuro2A s.c. tumors. The 64 Cu-labeled IT-101 displays a biphasic plasma elimination. Approximately 8% of the injected dose is rapidly cleared as a low-molecular-weight fraction through the kidneys. The remaining material circulates in plasma with a terminal half-life of 13.3 h. Steadily increasing concentrations, up to 11% injected dose per cm 3 , are observed in the tumor over 24 h, higher than any other tissue at that time. A 3-compartment model is used to determine vascular permeability and nanoparticle retention in tumors, and is able to accurately represent the experimental data. The calculated tumor vascular permeability indicates that the majority of nanoparticles stay intact in circulation and do not disassemble into individual polymer strands. A key assumption to modeling the tumor dynamics is that there is a ''sink'' for the nanoparticles within the tumor. Histological measurements using confocal microscopy show that IT-101 localizes within tumor cells and provides the sink in the tumor for the nanoparticles.cancer ͉ camptothecin ͉ cyclodextrin ͉ polymer ͉ intracellular delivery C hemotherapeutics are the mainstay of cancer treatment for advanced and/or metastatic tumors. However, their effectiveness is typically limited by toxicity in healthy, normal tissues with rapidly dividing cells, such as bone marrow or the gastrointestinal tract. One approach to increase the therapeutic index of chemotherapeutics is site-directed delivery by using various carrier systems. Numerous types of delivery technologies have been developed for this purpose, such as liposomes (1, 2), conjugates with antibodies or small molecules targeted to tumor antigens (3, 4), and macromolecular polymer carriers (5). Carrier-drug composites are nanoscaled therapeutics, and nanoparticle cancer therapeutics that have been used in humans have been reviewed elsewhere (6).The use of nanoscaled therapeutics takes advantage of the unique tumor physiology characterized by a high density of abnormal blood vessels, high vascular permeability, and decreased rate of clearance due to a lack of lymphatic drainage, all of which act together to cause accumulation of macromolecules through the enhanced permeability and retention (EPR) effect (7). The magnitude of this effect is affected by a number of parameters that are either host-related (tumor perfusion, vascularity, vascular permeability) or nanoparticle-related (plasma half-life, clearance, hydrodynamic size, surface char...

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“…The assembly is not limited to CPT (IT-101) as other conjugated molecules also allow for nanoparticle formation (22).…”

Section: Discussionmentioning

confidence: 99%

Pharmacokinetics and tumor dynamics of the nanoparticle IT-101 from PET imaging and tumor histological measurements

Schluep

Hwang

Hildebrandt

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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“…Over the last decade, various tubulysin analogues with different cytotoxic potency were synthesized (5,6). Preclinical studies showed that tubulysins are too toxic for use as single-agent chemotherapeutics (7), and therefore targeted therapy becomes an appealing option to enable the administration of higher doses of tubulysins, thus avoiding or minimizing systemic toxicity. Combining targeted therapy of mAbs with toxic agents might in fact result in highly specific and well-tolerated ADCs (8).…”

Section: Introductionmentioning

confidence: 99%

Development of Novel ADCs: Conjugation of Tubulysin Analogues to Trastuzumab Monitored by Dual Radiolabeling

et al. 2014

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Tubulysins are highly toxic tubulin-targeting agents with a narrow therapeutic window that are interesting for application in antibody-drug conjugates (ADC). For full control over drug-antibody ratio (DAR) and the effect thereof on pharmacokinetics and tumor targeting, a dual-labeling approach was developed, wherein the drug, tubulysin variants, and the antibody, the anti-HER2 monoclonal antibody (mAb) trastuzumab, are radiolabeled.131 I-radioiodination of two synthetic tubulysin A analogues, the less potent TUB-OH (IC 50 > 100 nmol/L) and the potent TUB-OMOM (IC 50 , $1 nmol/L), and their direct covalent conjugation to 89 Zrtrastuzumab were established. Radioiodination of tubulysins was 92% to 98% efficient and conversion to N-hydroxysuccinimide (NHS) esters more than 99%; esters were isolated in an overall yield of 68% AE 5% with radiochemical purity of more than 99.5%. Conjugation of 131 I-tubulysin-NHS esters to 89 Zr-trastuzumab was 45% to 55% efficient, resulting in ADCs with 96% to 98% radiochemical purity after size-exclusion chromatography. ADCs were evaluated for their tumor-targeting potential and antitumor effects in nude mice with tumors that were sensitive or resistant to trastuzumab, using ado-trastuzumab emtansine as a reference. ADCs appeared stable in vivo. An average DAR of 2 and 4 conferred pharmacokinetics and tumor-targeting behavior similar to parental trastuzumab. Efficacy studies using single-dose TUB-OMOM-trastuzumab (DAR 4) showed dose-dependent antitumor effects, including complete tumor eradications in trastuzumab-sensitive tumors in vivo. TUB-OMOM-trastuzumab (60 mg/kg) displayed efficacy similar to ado-trastuzumab emtansine (15 mg/kg) yet more effective than trastuzumab. Our findings illustrate the potential of synthetic tubulysins in ADCs for cancer treatment. Cancer Res; 74(20); 5700-10. Ó2014 AACR.

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“…Tumor suppressor gene p53 is a key element in the induction of cell cycle arrest and apoptosis following DNA damage or cellular stress through regulating the transcription and expression of proapoptotic protein Bax (Lane, 1992;Yamaguchi et al, 2003;Harris et al, 2005). The increased ratio of proapoptotic protein Bax/ antiapoptotic protein Bcl-2 results in the dispersal of mitochondrium transmembrane potential, which indicates the dysfunction of the mitochondria and triggers the cell death (Fujita et al, 1992;Schluep et al, 2009). Our results showed that SBC-treatment decreased the level of ΔΨm by using JC-1 stain and flow cytometry assay (Figure 4).…”

Section: Discussionmentioning

confidence: 99%

S-benzyl-cysteine-mediated Cell Cycle Arrest and Apoptosis Involving Activation of Mitochondrial-dependent Caspase Cascade through the p53 Pathway in Human Gastric Cancer SGC-7901 Cells

Sun

Meng²,

Shen³

et al. 2013

Asian Pacific Journal of Cancer Prevention

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S-benzyl-cysteine (SBC) is a structural analog of S-allylcysteine (SAC), which is one of the major watersoluble compounds in aged garlic extract. In this study, anticancer activities and the underlying mechanisms of SBC action were investigated and compared these with those of SAC using human gastric cancer SGC-7901 cells. SBC significantly suppressed the survival rate of SGC-7901 cells in a concentration-and time-dependent manner, and the inhibitory activities of SBC were stronger than those of SAC. Flow cytometry revealed that SBC induced G2-phase arrest and apoptosis in SGC-7901 cells. Typical apoptotic morphological changes were observed by Hoechst 33258 dye assay. SBC-treatment dramatically induced the dissipation of mitochondrial membrane potential (ΔΨm), and enhanced the enzymatic activities of caspase-9 and caspase-3 whilst hardly affecting caspase-8 activity. Furthermore, Western blotting indicated that SBC-induced apoptosis was accompanied by up-regulation of the expression of p53, Bax and the down-regulation of Bcl-2. Taken together, this study suggested that SBC exerts cytotoxic activity involving activation of mitochondrial-dependent apoptosis through p53 and Bax/Bcl-2 pathways in human gastric cancer SGC-7901 cells.

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Polymeric Tubulysin-Peptide Nanoparticles with Potent Antitumor Activity

Cited by 55 publications

References 32 publications

Pharmacokinetics and tumor dynamics of the nanoparticle IT-101 from PET imaging and tumor histological measurements

Pharmacokinetics and tumor dynamics of the nanoparticle IT-101 from PET imaging and tumor histological measurements

Development of Novel ADCs: Conjugation of Tubulysin Analogues to Trastuzumab Monitored by Dual Radiolabeling

S-benzyl-cysteine-mediated Cell Cycle Arrest and Apoptosis Involving Activation of Mitochondrial-dependent Caspase Cascade through the p53 Pathway in Human Gastric Cancer SGC-7901 Cells

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