Hydrazone Derivative Of Doxorubicin Research Articles

Targeted Drug Delivery Biopolymers Effectively Inhibit Breast Tumor Growth and Prevent Doxorubicin-Induced Cardiotoxicity.

The anticancer agent doxorubicin(dox) has been widely used in the treatment of a variety of hematological malignancies and solid tumors. Despite doxorubicin’s efficiency in killing tumor cells, severe damage to healthy tissues, along with cardiotoxicity, limits its clinical use. To overcome these adverse side effects, improve patient safety, and enhance therapeutic efficacy, we have designed a thermally responsive biopolymer doxorubicin carrier that can be specifically targeted to tumor tissue by locally applying mild hyperthermia (41 °C). The developed drug vehicle is composed of the following: a cell penetrating peptide (SynB1) to promote tumor and cellular uptake; thermally responsive Elastin-like polypeptide (ELP); and the (6-maleimidocaproyl) hydrazone derivative of doxorubicin (DOXO-EMCH) containing a pH-sensitive hydrazone linker that releases doxorubicin in the acidic tumor environment. We used the in vivo imaging system, IVIS, to determine biodistribution of doxorubicin-delivered ELP in MDA-MB-231 xenografts in nude mice. Tumor bearing mice were treated with a single IV injection of 10 mg/kg doxorubicin equivalent dose with free doxorubicin, thermally responsive SynB1 ELP 1-DOXO, and a thermally nonresponsive control biopolymer, SynB1 ELP 2-DOXO. Following a 2 h treatment with hyperthermia, tumors showed a 2-fold higher uptake when treated with SynB1 ELP 1-DOXO compared to free doxorubicin. Accumulation of the thermally non-responsive control SynB1 ELP2 –DOXO was comparable to free doxorubicin, indicating that an increase in dox accumulation with ELP is due to aggregation in response to thermal targeting. Higher levels of SynB1 ELP1–DOXO and SynB1 ELP2 –DOXO with respect to free doxorubicin were observed in kidneys. Fluorescence intensity from hearts of animals treated with SynB1 ELP1–DOXO show a 5-fold decrease in accumulation of doxorubicin than the same dose of free doxorubicin. SynB1-ELP1-DOXO biopolymers demonstrated a 6-fold increase in tumor/heart ratio in comparison to free doxorubicin, indicating preferential accumulation of the drug in tumors. These results demonstrate that thermally targeted polymers are a promising therapy to enhance tumor targeting and uptake of anticancer drugs and to minimize free drug toxicity in healthy tissues, representing a great potential for clinical application.

Abstract 3708: Targeted delivery of doxorubicin to glioblastomas by thermally sensitive polypeptides

Abstract Glioblastoma (GBM) ranks among the most common, aggressive, and least curable cancers due to a strong tendency for intracranial dissemination, high proliferation potential and inherent tumor resistance to radiation or chemotherapy. Current treatments face the critical challenge of adverse treatment effects in normal tissue within the brain itself and also when the agent cannot adequately penetrate the blood brain barrier (BBB) to reach the tumor microenvironment. We have developed a system to selectively deliver chemotherapeutic doxorubicin to GBM tumors. This carrier is based on elastin-like polypeptide (ELP), which is soluble at physiological temperatures but undergoes a phase transition and accumulates at tumor sites with externally applied, mild (40-41°C) hyperthermia. The CPP-ELP-Dox conjugate consists of a cell penetrating peptide (CPP), which facilitates transcytosis through the BBB and cell entry, and the 6-maleimidocaproyl hydrazone derivative of doxorubicin (Dox) at the C-terminus of ELP. The acid-sensitive hydrazone linker ensures release of Dox in the lysosomes/endosomes after cellular uptake of the drug conjugate. We have shown that CPP-ELP-Dox effectively inhibits cell proliferation in three GBM cell lines; GBM6, D54, and U251 with IC50 values of 250 nM, 60nM, and 30nM, respectively. Both the free drug and CPP-ELP-Dox conjugate exhibited similar in vitro cytotoxicity, although their subcellular localization was considerably different. The Dox conjugate was mainly dispersed in the cytoplasm, while free drug was largely dispersed in the cytoplasm but also had partial nuclear accumulation. The accumulation of free Dox in GBM cells was measured by flow cytometry to determine whether the cytotoxic activity of free Dox or CPP- ELP-Dox is related to intracellular Dox levels. Intracellular Dox concentration was increased in the CPP-ELP-Dox cells compared to that in the free Dox cells, which positively correlates with cytotoxic activity. Flow cytometry was also used to quantitatively investigate apoptosis of GBM cells. After incubation for 24 h, the total apoptosis percentage of free Dox was 1.5% in GBM6, 6% in D54, and 7% in U251 cells. However, the total apoptosis rates of CPP-ELP-Dox treated cells were 5%, 12% and 5% in GBM6, D54, and U251 cells respectively, which confirms increased apoptosis compared to free Dox treated cells. Cell cycle analysis of GBM cells treated with free Dox showed enhanced arrest of the cells in G1 phase, while there was increased percentage arrest of cells in G2 phase in cells treated with CPP-ELP-Dox.In summary, our findings demonstrate that CPP-ELP-Dox effectively kills GBM cells. Development of such a drug carrier has the potential to greatly improve current therapeutic approaches for GBM by increasing the specificity and efficacy of treatment and reducing cytotoxicity in normal tissues. Citation Format: Sonja Dragojevic, Rebecca B. Mackey, Felix Kratz, Drazen Raucher. Targeted delivery of doxorubicin to glioblastomas by thermally sensitive polypeptides [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3708.

Albumin Binding Domain Fusing R/K-X-X-R/K Sequence for Enhancing Tumor Delivery of Doxorubicin.

For the purpose of improving the tumor delivery of doxorubicin (DOX), a kind of peptide-DOXO conjugate was designed and prepared, in which the peptide composed of an albumin-binding domain (ABD) and a tumor-specific internalizing sequence (RGDK or RPARPAR) was conjugated to a (6-maleimidocaproyl) hydrazone derivative of doxorubicin (DOXO-EMCH). The doxorubicin uptake by lung cancer cell line of A549 evidenced that the conjugates are capable of being internalized through a tumor-specific sequence mediated manner, and the intracellular imaging of distribution in A549 cell demonstrated that the conjugated doxorubicin can be delivered to the cell nucleus. The A549 cell cytotoxicity of peptide-DOXO conjugates was presented with IC50 values and shown in the range of about 9-11 μM. Pharmacokinetics study revealed that both conjugates exhibited nearly 5.5 times longer half-time than DOX, and about 4 times than DOXO-EMCH. The in vivo growth inhibitions of the two peptide-DOXO conjugates on BALB/c nude mice bearing A549 tumor (47.78% for ABD-RGDK-DOXO and 47.09% for ABD-RPARPAR-DOXO) were much stronger than that of doxorubicin and DOXO-EMCH (24.28% and 25.67% respectively) at a doxorubicin equivalent dose. Besides, the in vivo fluorescence imaging study confirmed that the peptide markedly increased the payload accumulation in tumor tissues and indicated that albumin binding domain fusing tumor-specific sequence effectively enhanced the tumor delivery of doxorubicin and thus improved its therapeutic potency.

Abstract 3106: Targeted delivery via Elastin Like Polypeptide: Biodistribution of a doxorubicin derivative in MDA-MB231 human breast cancer xenografts in mice

Abstract The anticancer agent doxorubicin has been widely used in the treatment of a variety of hematological malignancies and solid tumors. Despite doxorubicin’s efficiency in eradicating tumor cells, severe damage to healthy tissues, along with cardiotoxicity, limits its use in clinics. To overcome adverse side effects, improve patient safety, and enhance therapeutic efficacy, we have designed a thermally responsive biopolymer doxorubicin carrier that can be specifically targeted to tumor tissue by locally applying mild hyperthermia (41 degrees C). The developed drug vehicle is composed of: a cell penetrating peptide (SynB1) to promote tumor and cellular uptake; thermally responsive Elastin like polypeptide (ELP); and the (6-maleimidocaproyl) hydrazone derivative of doxorubicin (DOXO-EMCH) containing a pH-sensitive hydrazine linker that releases dox in the acidic tumor environment. We used the in vivo imaging system, IVIS, to determine the biodistribution of doxorubicin-delivered ELP in MDA-MB231 triple negative human breast cancer cell line xenografts in nude mice. Tumor bearing mice were treated with a single IV injection of 10 mg/kg doxorubicin equivalent dose with free doxorubicin, thermally responsive SynB1 ELP 1-DOXO, and a thermally nonresponsive control biopolymer, SynB1 ELP 2-DOXO. Following a 2 hour treatment with hyperthermia, tumors showed a 2-fold higher uptake when treated with SynB1 ELP 1-DOXO compared to free doxorubicin. Accumulation of the thermally non-responsive control SynB1 ELP2 -DOXO was comparable to free doxorubicin, indicating that an increase in dox accumulation with ELP is due to aggregation in response to thermal targeting. Higher levels of SynB1 ELP1 -DOXO and SynB1 ELP2 -DOXO with respect to free doxorubicin were observed in kidneys. Fluorescence intensity from hearts of animals treated with SynB1 ELP1 - DOXO show a 5-fold lower accumulation of doxorubicin than the same dose of free doxorubicin. SynB1-ELP1-DOXO biopolymers demonstrated a 6-fold increase in tumor/heart ratio in comparison to free doxorubicin, indicating preferential accumulation of the drug carrier in tumors. Overall, thermally targeted polymers are a promising therapy to enhance tumor targeting and uptake of anticancer drugs and to minimize free drug toxicity in healthy tissues, representing a great potential for clinical application. Citation Format: Sonja Dragojevic, Jung Su Ryu, Felix Kratz, Drazen Raucher. Targeted delivery via Elastin Like Polypeptide: Biodistribution of a doxorubicin derivative in MDA-MB231 human breast cancer xenografts in mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3106. doi:10.1158/1538-7445.AM2017-3106

Evaluation of combination therapy schedules of doxorubicin and an acid-sensitive albumin-binding prodrug of doxorubicin in the MIA PaCa-2 pancreatic xenograft model

In this work, we evaluated combinations of doxorubicin with INNO-206, a (6-maleimidocaproyl)hydrazone derivative of doxorubicin (DOXO-EMCH) that is currently undergoing two phase II clinical trials, in a primarily chemoresistant tumor indication, i.e. pancreatic cancer. Thus, we compared the antitumor efficacy and tolerability of the following weekly intravenous treatments in the MIA PaCa-2 xenograft model: 3×6 mg doxorubicin (MTD), 3×24 mg/kg DOXO-EMCH (doxorubicin equivalents, MTD), 3×3 mg/kg doxorubicin followed 6h later by 3×12 mg/kg DOXO-EMCH, and 3×12 mg/kg DOXO-EMCH followed 6 h later by 3×3 mg/kg doxorubicin. Whereas therapy with doxorubicin only produced a moderate tumor inhibition, all other therapy arms induced complete and partial remissions up to the end of the experiment on day 43. Although the total amount of doxorubicin equivalents is 72 mg/kg when DOXO-EMCH is administered alone, but only 45 mg/kg doxorubicin equivalents are administered in the combination regimens, the antitumor efficacy in all treated groups was essentially identical, a surprising finding of this study. However, there were significant differences in the tolerability as assessed by the body weight changes: whereas therapy at the MTD of DOXO-EMCH (3×24 mg/kg) produced a body weight loss of -16% including one death, therapy with 3×12 mg/kg DOXO-EMCH followed 6h later by 3×3 mg/kg doxorubicin produced -7% body weight loss, and 3×3 mg/kg doxorubicin followed 6h later by 3×12 mg/kg DOXO-EMCH produced a body weight gain of +2% as a clear indication of minimal systemic toxicity. In addition, cell culture experiments revealed additive to synergistic effects when MIA PaCa-2 cells were exposed to doxorubicin followed 6h later to exposure of the albumin-bound form of DOXO-EMCH spanning a ratio of 1:5 to 5:1 (analyzed for synergistic, additive or antagonistic effects using the software program CalcuSyn(®)). This animal study demonstrates that the time-dependent schedule of an albumin-binding prodrug and a free drug has a critical influence on the overall tolerability. A combination of doxorubicin and DOXO-EMCH is currently being investigated in a phase Ib study.

Abstract 1760: Development of bisphosphonate prodrugs of doxorubicin for targeting bone metastases that are cleaved pH dependently or by cathepsin B

Abstract Bone metastases occur in up to 80 % of patients with advanced breast or prostate cancer and significantly affect the quality of life. Most frequently, bone metastases cause bone fractures, severe pain and hypercalcaemia. Current options for treating of bone metastases are surgery, radiotherapy, chemotherapy, hormone therapy, and the administration of bisphosphonates. These treatments are primarily palliative and can improve the quality of life in some cases, however without increasing the survival time of the patients. Bisphosphonates are presently the most active inhibitors of bone degradation, and they can reduce bone pain, bone destruction and tumor growth. Their therapeutic effects are due to the high affinity between bisphosphonates and the apatite structure of bone and bone metastases. In order to improve the outcome of treating bone metastases, new therapeutic approaches are urgently required. As bone-seeking agents, bisphosphonates show an uptake in the bone of 20-60% of the applied dose, and in general the uptake in bone metastases is 10-20-fold higher than in healthy bone tissue. In addition, bone metastases are characterized by an acidic pH and the over-expression of several proteases including cathepsins, matrix metalloproteases, plasmin and uPA. Surprisingly, no prodrug approaches have been reported to date that exploit the bone targeting effect of low-molecular weight bisphosphonates with a concomitant release of a bound drug in bone metastases. To this purpose, we developed water-soluble bisphosphonate prodrugs of doxorubicin for targeting bone metastases by conjugating a thiol-bearing aliphatic bisphosphonate with the 6-maleimidocaproyl hydrazone derivative of doxorubicin (1) that is cleaved pH dependently, or by attaching a maleimide derivative of the dipeptide Val-Ala-PABC (PABC = p-benzyloxycarbonyl) to the aliphatic bisphosphonate (2). Incubation studies with cathepsin B and 2 at 37 °C showed a cleavage of doxorubicin after two hours with a half time of ∼ 45 min and 1 released doxorubicin quantitatively at pH 5.0 after 2 h. The plasma stabilities (human and mouse) of both prodrugs were in the range of 3-6 h at 37 °C. Binding studies of 1 and 2 with a major component of bone, i.e. hydroxyapatite, demonstrated binding of 80-90 % of both prodrugs after 4 h at 37 °C. Finally, in an orientating toxicity study in nude mice the maximum tolerated dose (MTD) of 1 was three-fold higher compared to conventional doxorubicin whereas 2 showed essentially the same MTD as doxorubicin. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1760. doi:1538-7445.AM2012-1760

Abstract 4771: Improved antitumor efficacy of an acid-sensitive doxorubicin derivative delivered by thermally responsive elastin-like polypeptides

Abstract Doxorubicin is a widely used anticancer drug used in the treatment of various cancers. It acts as an intercalator of DNA and inhibits topoisomerase II thus preventing cell replication. Its side effects include nausea, myelosuppression, alopecia, and dose-limiting cardiotoxicity. Dox is nonspecific, and high doses are needed to treat cancer cells. These high doses, however, are also harmful to normal cells. Because of this toxicity to normal cells, there is a great need for a delivery system that will target dox to the tumor site. In our research, we have developed a tumor targeted drug delivery system comprising the elastin-like polypeptide (ELP) which is a thermally responsive macromolecule that remains soluble in physiologic temperature but aggregates upon heating at 42 °C in the tumor. The N-terminus of ELP was modified with the cell-penetrating peptide SynB1. The SynB1-ELP construct was further modified by the addition of an acid-sensitive hydrazone derivative of doxorubicin (DOXO), by conjugation with a 6-maleimidocaproyl moiety on the drug to a terminal cysteine residue on ELP. SynB1-ELP-DOXO was found to have a thermal transition temperature of 41 °C. This construct was 2-fold more effective in inhibiting MCF-7 breast cancer cell proliferation at 42 °C than at 37 °C, indicating that the hyperthermia-induced phase transition of ELP increases the local concentration of the drug. This inhibition may be due to apoptosis since apoptosis was enhanced 2.3-fold in MCF-7 cells when SynB1-ELP-DOXO aggregation was induced by hyperthermia. SynB1-ELP-DOXO had a similar accumulation inside the cell as free Dox as shown by confocal fluorescence imaging, and the uptake into the cell was increased by hyperthermia. In the in vivo studies, a marked reduction in tumor size was seen with SynB1-ELP-DOXO exposed to hyperthermia in the E0771 syngeneic breast cancer model in C57BL/6 mice. The efficacy of the construct was further proved by the animal's body weight increasing over time as compared to treatment with free Dox and a decreasing body weight. An ongoing study uses the combination of free Dox and SynB1-ELP-DOXO at lower doses to reduce tumor size. The ELP macromolecule can also be applied to other small molecule therapeutics opening a potential platform technology for this thermally responsive biopolymer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4771. doi:1538-7445.AM2012-4771

Abstract 779: Prodrug-mediated reversal of multidrug resistance in breast cancer cells

Abstract The P-glycoprotein (P-gp) is a 170 kDa protein that acts as an energy-dependent, transmembrane efflux pump and is encoded by the MDR1 gene. It has been shown to be responsible for multidrug resistance (MDR) in a defined subpopulation of breast cancer patients and thus represents a molecular target for circumventing MDR in this tumor indication. Third generation MDR modulators have been developed that demonstrated high selectivity for P-gp with inhibitory activities in the low nanomolar range. Although some objective responses were achieved in clinical trials, combination therapy with these MDR-modulators caused unacceptable toxicity. Targeting P-gp inhibitors to the tumor site is a means to increase their therapeutic index, and in this context binding tailor-made prodrugs to circulating albumin is an established technology to reduce the toxicity and enhance the efficacy of anticancer drugs. In this work we consequently developed an acid-sensitive albumin-binding prodrug of the P-gp inhibitor zosuquidar (LY335979) in a two-step synthesis using a maleimide hydrazone linker system established in our laboratory that first introduces acetylbenzoic acid at the OH-group of zosuquidar followed by derivatization with 6-maleimidocaproyl hydrazide to form the acid-sensitive hydrazone bond. The maleimide group enables the prodrug to bind rapidly and selectively to the cysteine-34 position of endogenous albumin after intravenous administration. HPLC analysis demonstrated rapid albumin binding of the zosuquidar prodrug as well as the quantitative release of the acetylbenzoic ester derivative of zosuquidar at pH 5.0. Subsequently, its ability to circumvent MDR was tested in two doxorubicin-resistant breast carcinoma cell lines (MCF-7/ADR and MT-3/ADR). The MDR status of these cell lines can be reversed by zosuquidar which was confirmed in a rhodamine 123 assay using fluorescence microscopy and FACS analysis. Furthermore, zosuquidar as well its acid-sensitive albumin conjugate re-sensitized cells to doxorubicin as well to an albumin-binding prodrug of doxorubicin, i.e. the 6-maleimidocaproyl hydrazone derivative of doxorubicin, achieving IC50 values in the same order of magnitude as the parental cell lines. Thus a novel formulation of zosuquidar has been developed that may be used to improve the toxicity issues and tumor targeting properties of the original compound. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 779. doi:1538-7445.AM2012-779

Combination therapy with the albumin-binding prodrug of doxorubicin (INNO-206) and doxorubicin achieves complete remissions and improves tolerability in an ovarian A2780 xenograft model

We recently reported on the in superior in vivo antitumor efficacy of the (6-maleimidocaproyl)hydrazone derivative of doxorubicin (INNO-206, formerly DOXO-EMCH), an albumin-binding prodrug of doxorubicin with acid-sensitive properties (see Fig. 1), in three tumor models in this journal, i.e. in three xenograft models (breast carcinoma M3366, ovarian carcinoma A2780, and small cell lung cancer H209) as well as in an orthotopic pancreatic carcinoma model (AsPC-1) [1] Previously, INNO-206 has shown significantly improved activity over doxorubicin in two xenograft breast cancer models and an orthotopic murine renal cell carcinoma model [2] and recently against resistant and non resistant myeloma (see http//:www.cytrx.com). INNO-206 binds rapidly to circulating serum albumin and releases doxorubicin selectively at the tumor site due to incorporation of an acid-sensitive hydrazone bond. The accumulation of INNO-206 in tumor tissue combined with a favorable biodistribution [3] is due to the pathophysiology of tumor tissue, characterized by a high metabolic turnover, angiogenesis, hypervasculature, a defective vascular architecture and an impaired lymphatic drainage, the so-called EPR (enhanced and retention) effect [4]. As a carrier for INNO-206, we selected albumin, which is emerging as a versatile protein carrier for drug targeting and for improving the pharmacokinetic profile of peptideor protein-based drugs [5]. Albumin is a potential carrier for tumor targeting because it accumulates in solid tumors. In addition, we discovered that the HS-group of cysteine-34 of albumin is a unique and accessible functional group of a plasma protein for in situ prodrug conjugation considering that free thiol groups are absent from most circulating serum proteins except for albumin, which makes this group by far the most abundant thiol group in human plasma After injection directly into the blood stream, INNO-206 binds in situ to the cysteine-34 position of circulating albumin and is then transported in its albumin-bound form to the tumor site. INNO-206 is a prodrug of the anticancer agent doxorubicin in which doxorubicin is derivatized at its C-13 keto-position with a thiol-binding spacer molecule, i.e. 6-maleimidocaproic acid hydrazide. It contains an acidsensitive hydrazone linker that allows doxorubicin to be released either extracellularly in the slightly acidic environment often present in tumor tissue (pH range 6.0-6.8) [6] or intracellularly in acidic endosomal (pH 5.0-6.5) or lysosomal (pH 4.0-5.0) compartments after cellular uptake of the albumin conjugate by the tumor cell. INNO-206 was selected as an investigational product for clinical evaluation after toxicology studies in mice, rats, and dogs had shown a 2.5to 5-fold increase in the maximum tolerated dose (MTD) when compared to conventional doxoElectronic supplementary material The online version of this article (doi:10.1007/s10637-011-9686-5) contains supplementary material, which is available to authorized users.

INNO-206 (DOXO-EMCH), an Albumin-Binding Prodrug of Doxorubicin Under Development for Phase II Studies

The (6-maleimidocaproyl)hydrazone derivative of doxorubicin (INNO-206, formerly DOXO-EMCH) is a prodrug of the anticancer agent doxorubicin which is selectively bound to the cysteine-34 position of endogenous albumin within a few minutes after intravenous administration planned for 2011. Preclinically as well as clinically, the albuminbound form of INNO-206 has a large AUC, a small volume of distribution and low clearance compared to doxorubicin, uptake in solid tumors being mediated by the pathophysiology of tumor tissue, characterized by angiogenesis, hypervasculature, a defective vascular architecture, and an impaired lymphatic drainage. The prodrug contains an acid-sensitive hydrazone linker allowing doxorubicin to be released either extracellularly in the slightly acidic environment often present in tumor tissue or intracellularly in acidic endosomal or lysosomal compartments after cellular uptake of the albumin conjugate by the tumor cell. INNO-206 shows significantly superior antitumor efficacy over free doxorubicin in a spectrum of preclinical tumor models. In a phase I study, INNO-206 showed a good safety profile at doses up to 260 mg/m2 doxorubicin equivalents. Although not the primary end point of the phase I study, INNO-206 was able to induce tumor regressions in breast cancer, small cell lung cancer and sarcoma. Phase II studies against gastric cancer, pancreatic cancer and sarcoma are planned for the end of 2010.

Abstract 2653: Thermally targeted delivery of an acid-labile derivative of doxorubicin by elastin-like polypeptide

Abstract Doxorubicin (Dox) is an anthracycline used in the treatment of many types of cancer. It intercalates into the strands of DNA to inhibit the progression of topoisomerase II, stopping the cell from replicating. The side effects, however, are severe and include neutropenia, alopecia, nausea, myelosuppression, and cardiotoxicity. The drug is nonspecific; as a result, high doses are needed to treat cancer cells. These high doses are inadvertently harmful to normal cells. Therefore, there is a need for an efficient drug delivery system in order to deliver doxorubicin to the tumor site. Our lab has developed a macromolecular carrier that can provide this targeted delivery. This elastin-like polypeptide (ELP) is thermally responsive as it remains in solution at physiological temperature and aggregates upon heating at 42 °C. The N-terminus of ELP was modified with three different cell penetrating peptides (CPPs) - Bac, Tat, and SynB1. These peptides are derived from the bactenecin family of antimicrobial peptides, truncated version of the HIV-1 Tat protein, and porcine leukocytes, respectively. This study compared the efficiency of these three CPP-ELP carriers to deliver doxorubicin to the cells. ELP was attached to a hydrazone derivative of doxorubicin (DOXO) by conjugation of a 6-maleimidocaproyl moiety on the drug with a terminal cysteine residue on ELP. This linker allows the drug to be cleaved at acidic pH in the cell. The three CPP-ELP-DOXO conjugates had transition temperatures within the range of 38-42°C. All three carriers of DOXO inhibited MCF-7 breast cancer cell proliferation 2-fold more at 42 °C than at 37 °C, indicating that the hyperthermia induced phase transition of ELP does increase the local concentration of the drug. Inhibition of cell proliferation may be due to apoptosis, since apoptosis was enhanced 2.3-fold in MCF-7 cells when SynB1-ELP-DOXO aggregation was induced with hyperthermia. CPP-ELP-DOXO accumulated in cells to the same level as free Dox. Confocal imaging showed that when cells were treated with any of the three CPP-ELP-DOXO derivatives, Dox localized in the nucleus, similar to the free Dox. The results suggest that CPP-ELP-DOXO conjugates may provide a means to thermally target solid tumors. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2653.

Characterisation of the conjugate of the (6-maleimidocaproyl)hydrazone derivative of doxorubicin with lactosaminated human albumin by 13C NMR spectroscopy

In order to improve the efficacy of doxorubicin (DOXO) in the treatment of hepatocellular carcinomas, the drug was conjugated with lactosaminated human albumin (L-HSA), a hepatotropic drug carrier. Conjugation was performed using the (6-maleimidocaproyl)hydrazone derivative of the drug (DOXO-EMCH). The maleimide group of DOXO-EMCH reacts with the aminoacidic residues of the carrier forming stable bonds, whereas the hydrazone bond is rapidly hydrolysed in the acidic endosomal and lysosomal compartments of the cells allowing the intracellular release of DOXO. To identify the amino acids of L-HSA involved in the bond with DOXO-EMCH, in the present study we synthesized this compound with the 2,3 carbon atoms of the maleimide moiety enriched in the 13C isotope and used this labelled DOXO-EMCH to prepare two types of L-HSA conjugate. Type I was prepared in analogy to those studied in the anticancer experiments using tris(2-carboxyethyl)phosphine (TCEP) to reduce l-cysteine disulfides and make the sulfhydryl groups available for the reaction with DOXO-EMCH; type II was synthesized omitting TCEP. By 13C NMR spectroscopy we could demonstrate that in type I conjugate cysteine was the only amino acid residue that reacted with DOXO-EMCH, whereas in type II conjugate lysine was the only amino acid in the reaction with DOXO-EMCH. When hydrolysed in an acidic medium to cleave the hydrazone bond, type I conjugate released only DOXO, whereas type II conjugate also released a derivative of the drug.

Phase I and Pharmacokinetic Study of the (6-Maleimidocaproyl)Hydrazone Derivative of Doxorubicin

The (6-maleimidocaproyl)hydrazone derivative of doxorubicin (DOXO-EMCH) is an albumin-binding prodrug of doxorubicin with acid-sensitive properties that shows superior antitumor efficacy in murine tumor models and a favorable toxicity profile in mice, rats, and dogs compared with doxorubicin. The purpose of the phase I study was to characterize the toxicity profile of DOXO-EMCH, establish a recommended dose for phase II studies, and assess potential anticancer activity. A starting dose of 20 mg/m2 doxorubicin equivalents was chosen. Forty-one patients with advanced cancer disease were treated with an i.v. infusion of DOXO-EMCH once every 3 weeks at a dose level of 20 to 340 mg/m2 doxorubicin equivalents. Treatment with DOXO-EMCH was well tolerated up to 200 mg/m2 without manifestation of drug-related side effects. Myelosuppression (grade 1-2) and mucositis (grade 1-2) were the predominant adverse effects at dose levels of 260 mg/m2 and myelosuppression (grade 1-3) as well as mucositis (grade 1-3) were dose limiting at 340 mg/m2. No cardiac toxicity was observed. Of 30 of 41 evaluable patients, 12 patients (40%) had progressive disease, 15 patients (57%) had stable disease, and 3 patients (10%) had a partial remission. DOXO-EMCH showed a good safety profile and was able to induce tumor regressions in tumor types known to be anthracycline-sensitive tumors, such as breast cancer, small cell lung cancer, and sarcoma. The recommended doxorubicin equivalent dose for phase II studies is 260 mg/m2.

DOXO-EMCH (INNO-206): the first albumin-binding prodrug of doxorubicin to enter clinical trials

The (6-maleimidocaproyl)hydrazone derivative of doxorubicin (DOXO-EMCH) is an albumin-binding prodrug of doxorubicin with acid-sensitive properties that demonstrates superior antitumor efficacy in murine tumor models and a favorable toxicity profile in mice, rats and dogs, including significantly reduced cardiotoxicity. After intravenous administration, DOXO-EMCH binds rapidly to the Cys-34 position of circulating albumin and accumulates in solid tumors due to passive targeting. In a clinical Phase I study, the dose of doxorubicin could be increased by a factor of 4.5 – 340 mg/m² when 75 mg/m² of free doxorubicin is considered to be the dose that can be administered as a single agent concomitant with the typical spectrum of side effects (i.e., myelotoxicity and mucositis). DOXO-EMCH was able to induce tumor regressions in anthracycline-sensitive tumors (i.e., breast cancer, small cell lung cancer and sarcoma). Phase II studies will be initiated at the beginning of 2007.

Acute and repeat-dose toxicity studies of the (6-maleimidocaproyl)hydrazone derivative of doxorubicin (DOXO-EMCH), an albumin-binding prodrug of the anticancer agent doxorubicin

The (6-maleimidocaproyl)hydrazone derivative of doxorubicin (DOXO-EMCH) is an albumin-binding prodrug of doxorubicin with acid-sensitive properties that demonstrates superior antitumor efficacy in murine tumor models, and has been evaluated in a phase I study. In order to establish the toxicity profile of this prodrug, acute and repeat-dose toxicity studies were performed with DOXO-EMCH in CD1-mice, Sprague-Dawley rats and Beagle dogs. Although the objective of the acute toxicity studies was not the determination of LD50 values, the LD50 of DOXO-EMCH was >60 mg/kg doxorubicin equivalents in both male and female mice (the LD50 of doxorubicin in CD-1 mice is -12 mg/kg). In Sprague-Dawley rats, the LD50 was 23.4 and 45.9 mg/kg doxorubicin equivalents for males and females, respectively. For comparison, the LD50 of doxorubicin in Sprague-Dawley rats is -10.5 mg/kg. The major clinical sign noted following intravenous administration of DOXO-EMCH in mice and rats was a dose-dependent peripheral neuropathy which, in general, developed as a delayed toxicity 1-3 weeks after application. The observed neurotoxicity has been well documented for Sprague-Dawley rats treated with doxorubicin at a dose of 5 and 10 mg/kg. In Beagle dogs, LD10 was not reached for DOXO-EMCH at 4.5 mg/kg doxorubicin equivalents. A four-cycle intravenous study with DOXO-EMCH at dose levels of 4 x 2.5, 5.0 or 7.5 mg/kg doxorubicin equivalents in rats revealed approximately three-fold less side effects on the hemolymphoreticular system when compared to 4 x 2.5 mg/kg doxorubicin dose, whereas effects on the testes/oligospermia seem to be comparable between both drugs at equitoxic dose. A No Observable Adverse Effect Level (NOAEL) for DOXO-EMCH of 4 x 2.5 mg/kg doxorubicin equivalents was established in this study. This dose is equivalent to the maximum tolerated dose (MTD) of doxorubicin in rats. In a two-cycle study over a period of 6 weeks in Beagle dogs (intravenous administration of DOXO-EMCH at dose levels of 1.5, 3.0 or 4.5 mg/kg doxorubicin equivalents), dose-related systemic histamine-like reactions within the first 3 hours after injection were noted in all treated groups. Only transient and temporary effects on hematology, urinary function, as well as on histopathology in mid- and/or high-dose animals, were observed. The low dose of 2 x 1.5 mg/kg was considered to be the NOAEL in this study, which is equivalent to twice the MTD o f doxorubicin i nBeagle dogs. In summary, the toxicity studies with DOXO-EMCH in mice, rats or dogs have not identified any other special toxicity when compared to the toxicity data for doxorubicin. Preclinical tolerance of DOXO-EMCH was higher in mice, rats and dogs compared to doxorubicin. A dose of 20 mg/m2 doxorubicin equivalents was recommended as the starting dose for a phase I study with DOXO-EMCH.

Phase I dose-escalation and pharmacokinetic (PK) study of a(6-maleimidocaproyl)hydrazone derivative of doxorubicin (DOXO-EMCH) in patients with advanced cancers

2125 Background: The anthracyclines are among the most useful agents in the treatment of solid malignancies and exhibit a wide range of antitumor activity. Adriamycin is most commonly used, but therapy is associated with significant bone marrow and organ toxicities. Therefore, an albumin-binding prodrug of adriamycin with acid-sensitive properties, i.e. (6-maleimidocaproyl)hydrazone derivative of doxorubicin (DOXO-EMCH), was developed that binds to circulating albumin with high affinity after intravenous application in a first step thus preventing rapid diffusion of adriamycin into healthy tissue. Due to a passive accumulation of albumin in solid tumors, DOXO-EMCH is targeted to the tumor and releases adriamycin in the acidic environment of tumor tissue. DOXO-EMCH has shown superior antitumor efficacy and an improved toxicity profile in various animal models compared to adriamycin. The objectives of this phase I trial is to evaluate the safety profile and pharmacokinetics of DOXO-EMCH in order to assess the maximum tolerated dose (MTD), evaluate dose-limiting toxicity (DLT), and to preliminarily assess the antitumor activity of intravenous single dosing in 3 week intervals in patients with advanced cancer. Methods: Cohorts of 3 patients with advanced cancer disease were treated with an intravenous infusion of DOXO-EMCH over 30 minutes once every 3 weeks at dose levels 27 mg/m2 (20 mg/m2 adriamycin equivalent), 54 mg/m2 (40 mg/m2 adriamycin equivalent) and 108 m2 (80 mg/m2 adriamycin equivalent) so far. Blood sampling for of PK analysis was performed. Results: 10 patients (6 female, 4 male) were treated with DOXO-EMCH so far, median age was 55.8 years. Treatment with DOXO-EMCH was well tolerated up to 40 mg/m2 adriamycin equivalent, whereas treatment with 54mg/m2 adriamycin equivalent was still ongoing. The MTD was not established. One out of 3 patients evaluable for response had a minor response after 2 cycles of DOXO-EMCH dosed with 27 mg/m2. Conclusions: Intravenous infusion once every 3 weeks of DOXO-EMCH was well tolerated and showed potential antitumor activity. The study is ongoing. No significant financial relationships to disclose.

Phase I dose-escalation and pharmacokinetic (PK) study of a(6-maleimidocaproyl)hydrazone derivative of doxorubicin (DOXO-EMCH) in patients with advanced cancers

2125 Background: The anthracyclines are among the most useful agents in the treatment of solid malignancies and exhibit a wide range of antitumor activity. Adriamycin is most commonly used, but therapy is associated with significant bone marrow and organ toxicities. Therefore, an albumin-binding prodrug of adriamycin with acid-sensitive properties, i.e. (6-maleimidocaproyl)hydrazone derivative of doxorubicin (DOXO-EMCH), was developed that binds to circulating albumin with high affinity after intravenous application in a first step thus preventing rapid diffusion of adriamycin into healthy tissue. Due to a passive accumulation of albumin in solid tumors, DOXO-EMCH is targeted to the tumor and releases adriamycin in the acidic environment of tumor tissue. DOXO-EMCH has shown superior antitumor efficacy and an improved toxicity profile in various animal models compared to adriamycin. The objectives of this phase I trial is to evaluate the safety profile and pharmacokinetics of DOXO-EMCH in order to assess t...

Probing the cysteine-34 position of endogenous serum albumin with thiol-binding doxorubicin derivatives. Improved efficacy of an acid-sensitive doxorubicin derivative with specific albumin-binding properties compared to that of the parent compound.

We have recently proposed a macromolecular prodrug strategy for improved cancer chemotherapy based on two features (Kratz, F.; et al. J. Med. Chem 2000, 43, 1253-1256.): (a) rapid and selective binding of thiol-reactive prodrugs to the cysteine-34 position of endogenous albumin after intravenous administration and (b) release of the albumin-bound drug in the acidic environment at the tumor site due to the incorporation of an acid-sensitive bond between the drug and the carrier. To investigate this therapeutic strategy in greater depth, four (maleinimidoalkanoyl)hydrazone derivatives of doxorubicin were synthesized differing in the length of the aliphatic spacer (1, -(CH(2))(2)-; 2, -(CH(2))(3)-; 3, -(CH(2))(5)-; 4, -(CH(2))(7)-). The albumin-binding doxorubicin prodrugs, especially the (6-maleimidocaproyl)hydrazone derivative of doxorubicin (3), are rapidly and selectively bound to the cysteine-34 position of endogenous albumin. 3 was distinctly superior to the parent compound doxorubicin in three animal tumor models (RENCA, MDA-MB 435, and MCF-7) with respect to antitumor efficacy and toxicity.