A Phase I Study of Acapatamab, a Half-life Extended, PSMA-Targeting Bispecific T-cell Engager for Metastatic Castration-Resistant Prostate Cancer.

PURPOSE: Safety and efficacy of acapatamab, a prostate-specific membrane antigen (PSMA) x CD3 bispecific T-cell engager were evaluated in a first-in-human study in metastatic castration-resistant prostate cancer (mCRPC). PATIENTS AND METHODS: Patients with mCRPC refractory to androgen receptor pathway inhibitor therapy and taxane-based chemotherapy received target acapatamab doses ranging from 0.003 to 0.9 mg in dose exploration (seven dose levels) and 0.3 mg (recommended phase II dose) in dose expansion intravenously every 2 weeks. Safety (primary objective), pharmacokinetics, and antitumor activity (secondary objectives) were assessed. RESULTS: In all, 133 patients (dose exploration, n = 77; dose expansion, n = 56) received acapatamab. Cytokine release syndrome (CRS) was the most common treatment-emergent adverse event seen in 97.4% and 98.2% of patients in dose exploration and dose expansion, respectively; grade ≥ 3 was seen in 23.4% and 16.1%, respectively. Most CRS events were seen in treatment cycle 1; incidence and severity decreased at/beyond cycle 2. In dose expansion, confirmed prostate-specific antigen (PSA) responses (PSA50) were seen in 30.4% of patients and radiographic partial responses in 7.4% (Response Evaluation Criteria in Solid Tumors 1.1). Median PSA progression-free survival (PFS) was 3.3 months [95% confidence interval (CI): 3.0-4.9], radiographic PFS per Prostate Cancer Clinical Trials Working Group 3 was 3.7 months (95% CI: 2.0-5.4). Acapatamab induced T-cell activation and increased cytokine production several-fold within 24 hours of initiation. Treatment-emergent antidrug antibodies were detected in 55% and impacted serum exposures in 36% of patients in dose expansion. CONCLUSIONS: Acapatamab was safe and tolerated and had a manageable CRS profile. Preliminary signs of efficacy with limited durable antitumor activity were observed. Acapatamab demonstrated pharmacokinetic and pharmacodynamic activity.

ETV4 Is Necessary for Estrogen Signaling and Growth in Endometrial Cancer Cells.

Estrogen signaling through estrogen receptor alpha (ER) plays a major role in endometrial cancer risk and progression, however, the molecular mechanisms underlying ER's regulatory role in endometrial cancer are poorly understood. In breast cancer cells, ER genomic binding is enabled by FOXA1 and GATA3, but the transcription factors that control ER genomic binding in endometrial cancer cells remain unknown. We previously identified ETV4 as a candidate factor controlling ER genomic binding in endometrial cancer cells, and here we explore the functional importance of ETV4. Homozygous deletion of ETV4, using CRISPR/Cas9, led to greatly reduced ER binding at the majority of loci normally bound by ER. Consistent with the dramatic loss of ER binding, the gene expression response to estradiol was dampened for most genes. ETV4 contributes to estrogen signaling in two distinct ways. ETV4 loss affects chromatin accessibility at some ER bound loci and impairs ER nuclear translocation. The diminished estrogen signaling upon ETV4 deletion led to decreased growth, particularly in 3D culture, where hollow organoids were formed and in vivo in the context of estrogen-dependent growth. These results show that ETV4 plays an important role in estrogen signaling in endometrial cancer cells. SIGNIFICANCE: Estrogen receptor alpha (ER) is a key oncogene in endometrial cancer. This study uncovers ETV4 as an important factor in controlling the activity of ER and the growth of endometrial cancer cells. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/6/1234/F1.large.jpg.

Clinical Performance of SurePath™ Preservative Compared to PreservCyt® with Cobas® and Hybrid Capture® 2 HPV Tests in a Colposcopy Population.

BACKGROUND: Until recently, no HPV test had been US FDA-approved for SurePath preservative. Clinical performance remains incompletely understood. The clinical performances of the Cobas HPV Test (Cobas) and Hybrid Capture 2 High-Risk HPV DNA Test (HC2) with PreservCyt and SurePath preservatives were compared. METHODS: Cervical cytology samples were collected in both preservatives in random order from women age 21+ (n = 244) referred for colposcopy. Before cytology processing and pelleting, SurePath samples were tested by the Cobas test with and without buffered SDS heat pretreatment. SurePath pellets were tested by the HC2 test and by the Cobas test (with pretreatment). Performance characteristics were calculated in relation to cases of cervical in-traepithelial neoplasia grade 2 or higher (CIN2+) as the clinical target outcome. All HPV-positive samples were also genotyped with the Linear Array test. RESULTS: CIN2+ was detected in 42 patients (17.2%). For both HPV tests, there was a trend towards higher positivity and sensitivity for SurePath compared to PreservCyt preservative. The Cobas test had higher sensitivity than HC2 and the HC2 test had higher specificity than Cobas. Pretreated SurePath samples produced results similar to untreated ones, despite a two-fold dilution during pretreatment [sensitivity %: 95.1 (82.2 - 99.2) vs. 94.3 (79.5 - 99.0); specificity %: 33.0 (26.6 - 40.1) vs. 33.0 (26.4 - 40.3)]. CONCLUSIONS: There was good agreement between the preservatives and HPV tests in detecting HPV and between the Cobas and Linear Array tests for genotyping HR-HPV. These trends were not statistically significant due to the limited number of CIN2+ cases. However, these data may help in evaluations of preservative selection for colposcopy samples. Pre-treatment for Cobas testing eliminated invalid results due to clots. The Cobas test has been FDA-approved for use with heat pretreated SurePath samples.

Clinical and Genomic Crosstalk between Glucocorticoid Receptor and Estrogen Receptor α In Endometrial Cancer.

Steroid hormone receptors are simultaneously active in many tissues and are capable of altering each other's function. Estrogen receptor α (ER) and glucocorticoid receptor (GR) are expressed in the uterus, and their ligands have opposing effects on uterine growth. In endometrial tumors with high ER expression, we surprisingly found that expression of GR is associated with poor prognosis. Dexamethasone reduced normal uterine growth in vivo; however, this growth inhibition was abolished in estrogen-induced endometrial hyperplasia. We observed low genomic-binding site overlap when ER and GR are induced with their respective ligands; however, upon simultaneous induction they co-occupy more sites. GR binding is altered significantly by estradiol with GR recruited to ER-bound loci that become more accessible upon estradiol induction. Gene expression responses to co-treatment were more similar to estradiol but with additional regulated genes. Our results suggest phenotypic and molecular interplay between ER and GR in endometrial cancer.

Endometrial Cancers Harboring Mutated Fibroblast Growth Factor Receptor 2 Protein Are Successfully Treated With a New Small Tyrosine Kinase Inhibitor in an Orthotopic Mouse Model.

OBJECTIVES: AL3818 (anlotinib) is a receptor tyrosine kinase inhibitor targeting vascular endothelial growth factor receptors (VEGFR1, VEGFR2/KDR, and VEGFR3), stem cell factor receptor (C-kit), platelet-derived growth factor (PDGFß), and fibroblast growth factor receptors (FGFR1, FGFR2, and FGFR3). This study evaluates the efficacy of AL3818 studying tumor regression in an orthotopic murine endometrial cancer model. METHODS: We tested the cytotoxicity of AL3818 on a panel of 7 human endometrial cancer cell lines expressing either wild-type or mutant FGFR2 and also assessed the in vivo antitumor efficacy in a murine, orthotopic AN3CA endometrial cancer model. AL3818 was administered daily per os either alone or in combination with carboplatin and paclitaxel, which represent the current standard of adjuvant care for endometrial cancer. RESULTS: AL3818 significantly reduces AN3CA cell number in vitro, characterized by high expression of a mutated FGFR2 protein. Daily oral administration of AL3818 (5 mg/kg) resulted in a complete response in 55% of animals treated and in a reduced tumor volume, as well as decreased tumor weights of AN3CA tumors by 94% and 96%, respectively, following a 29-day treatment cycle. Whereas carboplatin and paclitaxel failed to alter tumor growth, the combination with AL3818 did not seem to exhibit a superior effect when compared with AL3818 treatment alone. CONCLUSIONS: AL3818 shows superior efficacy for the treatment of endometrial cancer irresponsive to conventional carboplatin and paclitaxel combination and warrants further investigation.

Thermosensitive hydrogels a versatile concept adapted to vaginal drug delivery.

Vaginal drug delivery represents an attractive strategy for local and systemic delivery of drugs otherwise poorly absorbed after oral administration. The rather dense vascular network, mucus permeability and the physiological phenomenon of the uterine first-pass effect can all be exploited for therapeutic benefit. However, several physiological factors such as an acidic pH, constant secretion, and turnover of mucus as well as varying thickness of the vaginal epithelium can impact sustained drug delivery. In recent years, polymers have been designed to tackle challenges mentioned above. In particular, thermosensitive hydrogels hold great promise due to their stability, biocompatibility, adhesion properties and adjustable drug release kinetics. Here, we discuss the physiological and anatomical uniqueness of the vaginal environment and how it impacts the safe and efficient vaginal delivery and also reviewed several thermosensitive hydrogels deemed suitable for vaginal drug delivery by addressing specific characteristics, which are essential to engage the vaginal environment successfully.

Use of a highly parallel microfluidic flow cell array to determine therapeutic drug dose response curves.

A high-throughput, microfluidic flow cell array (MFCA) system has been modified to enable drug screening against small-volume cell-, and tissue cultures. The MFCA is composed of a 3D channel network that simultaneously flows fluids through forty-eight 830 µm by 500 µm flow cells, which physically divide and fluidically seal an existing culture into multiple compartments when docked onto the surface of a cell or tissue culture dish. The modified system provides temperature (37 °C) and CO2/pH level controls, while continuously flowing solutions (media or other liquid such as drug suspensions) over the cells/tissues. These assays were enhanced and validated using inverted microscopy and fluorescent staining techniques which also allow real time viability and toxicity assessments. This work presents the results of this new generation in vitro drug testing assay performed using this modified MFCA system. This setup allows the testing of 48 drug combinations on 48 different cell-, tissue specimen at once under flow conditions. All 48 flow cells were utilized to test 5 different concentrations of cisplatin (CDDP). CDDP solutions in various concentrations were continually flowed over cultured human ovarian cancer cells for 48 h. Viability assessments were performed using red-orange calcein and SYTOX ® Green nucleic acid stains. Cells were imaged at the beginning and end of the experiment (48 h). In order to compare and validate MFCAs suitability as drug screening assay, MTT assays were performed on cells. We found that both, MTT and MFCA assays generated dose-response curves with similar profiles. Innovative advantages of the MFCA system include the ability of handling smaller amounts of solutions compared to conventional and current state of the art drug screening and cell viability/toxicity methods. It also provides the ability to continually deliver fresh solution to the cell samples, while eliminating wastes that are produced. Based on our here reported findings MFCA may have a strong potential of providing a more physiological model than current state of the art static MTT assays.

Imiquimod Induces Apoptosis in Human Endometrial Cancer Cells In vitro and Prevents Tumor Progression In vivo.

PURPOSE: The increasing incidence of endometrial cancer (EC), in younger age at diagnosis, calls for new tissue-sparing treatment options. This work aims to evaluate the potential of imiquimod (IQ) in the treatment of low-grade EC. METHODS: Effects of IQ on the viabilities of Ishikawa and HEC-1A cells were evaluated using MTT assay. The ability of IQ to induce apoptosis was evaluated by testing changes in caspase 3/7 levels and expression of cleaved caspase-3, using luminescence assay and western blot. Apoptosis was confirmed by flow cytometry and the expression of cleaved PARP. Western blot was used to evaluate the effect of IQ on expression levels of Bcl-2, Bcl-xL, and BAX. Finally, the in vivo efficacy of IQ was tested in an EC mouse model. RESULTS: There was a decrease in EC cell viability following IQ treatment as well as increased caspase 3/7 activities, cleaved caspase-3 expression, and Annexin-V/ 7AAD positive cell population. Western blot results showed the ability of IQ in cleaving PARP, decreasing Bcl-2 and Bcl-xL expressions, but not affecting BAX expression. In vivo study demonstrated IQ's ability to inhibit EC tumor growth and progression without significant toxicity. CONCLUSIONS: IQ induces apoptosis in low-grade EC cells in vitro, probably through its direct effect on Bcl-2 family protein expression. In, vivo, IQ attenuates EC tumor growth and progression, without an obvious toxicity. Our study provides the first building block for the potential role of IQ in the non-surgical management of low-grades EC and encouraging further investigations.

Design and Characterization of Bioengineered Cancer-Like Stem Cells.

Cancer stem cells (CSCs) are a small subset of cancer cells responsible for maintenance and progression of several types of cancer. Isolation, propagation, and the differentiation of CSCs in the proper stem niches expose the intrinsic difficulties for further studies. Here we show that induced cancer like stem cells (iCLSCs) can be generated by in vitro oncogenic manipulation of mouse embryonic stem cells (mESCs) with well-defined oncogenic elements; SV40 LTg and HrasV12 by using a mouse stem virus long terminal repeat (MSCV-LTR)-based retroviral system. The reprogrammed mESCs using both oncogenes were characterized through their oncogenic gene expression, the enhancement of proliferation, and unhampered maintenance of stem properties in vitro and in vivo. In addition, these transformed cells resulted in the formation of malignant, immature ovarian teratomas in vivo. To successfully further expand these properties to other organs and species, more research needs to be done to fully understand the role of a tumor- favorable microenvironment. Our current study has provided a novel approach to generate induced cancer like stem cells through in vitro oncogenic reprogramming and successfully initiated organ-specific malignant tumor formation in an orthotopic small animal cancer model.

Enhanced thermogenic program by non-viral delivery of combinatory browning genes to treat diet-induced obesity in mice.

Thermogenic program (also known as browning) is a promising and attractive anti-obesity approach. Islet amyloid polypeptide (IAPP) and irisin have emerged as potential browning hormones that hold high potential to treat obesity. Here, we have constructed a dual browning gene system containing both IAPP and irisin (derived from fibronectin type III domain containing 5; FNDC5) combined with 2A and furin self-cleavage sites. Intraperitoneal administration of the construct complexed with a linear polyethylenimine into diet-induced obese mice demonstrated the elevation of anti-obesogenic effects characterized as the decreased body weight, adiposity, and levels of glucose and insulin. In addition, the construct delivery increased energy expenditure and the expression of core molecular determinants associated with browning. The additional advantages of the dual browning gene construct delivery compared to both single gene construct delivery and dual peptide delivery can be emphasized on efficacy and practicability. Hence, we have concluded that dual browning gene delivery makes it therapeutically attractive for diet-induced obesity treatment.

Combinatorial gene construct and non-viral delivery for anti-obesity in diet-induced obese mice.

The combinatorial peptidergic therapy of islet amyloid polypeptide (IAPP) and leptin (LEP) analogues was once an optimistic option in treating obese animals and patients. However, the need for frequent administrations and its negative side effects prevent it from being a viable choice. Here, we developed a combinatorial gene therapy of IAPP and LEP, where two genes are inserted into a single plasmid with self-cleaving furin and 2A sites to treat diet-induced obese (DIO) mice. The developed plasmid DNA (pDNA) individually produced both IAPP and LEP peptides in vitro and in vivo. The pDNA was delivered with a non-viral polymeric carrier, and its once-a-week administrations demonstrated a synergistic loss of body weight and significant reductions of fat mass, blood glucose, and lipid levels in DIO mice. The results suggest that the combinatorial gene therapy would have higher potential than the peptidergic approach for future translation due to its improved practicability.

An estrogen-induced endometrial hyperplasia mouse model recapitulating human disease progression and genetic aberrations.

Endometrial hyperplasia (EH) is a condition originating from uterine endometrial glands undergoing disordered proliferation including the risk to progress to endometrial adenocarcinoma. In recent years, a steady increase in EH cases among younger women of reproductive age accentuates the demand of therapeutic alternatives, which emphasizes that an improved disease model for therapeutic agents evaluation is concurrently desired. Here, a new hormone-induced EH mouse model was developed using a subcutaneous estradiol (E2)-sustained releasing pellet, which elevates the serum E2 level in mice, closely mimicking the effect known as estrogen dominance with underlying, pathological E2 levels in patients. The onset and progression of EH generated within this model recapitulate a clinically relevant, pathological transformation, beginning with disordered proliferation developing to simple EH, advancing to atypical EH, and then progressing to precancerous stages, all following a chronologic manner. Although a general increase in nuclear progesterone receptor (PR) expression occurred after E2 expression, a total loss in PR was noted in some endometrial glands as disease advanced to simple EH. Furthermore, estrogen receptor (ER) expression in the nucleus of endometrial cells was reduced in disordered proliferation and increased when EH progressed to atypical EH and precancerous stages. This EH model also resembles other pathological patterns found in human disease such as leukocytic infiltration, genetic aberrations in ß-catenin, and joint phosphatase and tensin homolog/paired box gene 2 (PTEN/PAX2) silencing. In summary, this new and comprehensively characterized EH model is cost-effective, easily reproducible, and may serve as a tool for preclinical testing of therapeutic agents and facilitate further investigation of EH.

Thermosensitive progesterone hydrogel: a safe and effective new formulation for vaginal application.

PURPOSE: The safe and functional delivery of progesterone through the vaginal route remains an unmet clinical need. The purpose of this work is to prepare a new progesterone (P4) gel for vaginal application using a thermosensitive mucoadhesive polymer, glycol chitin (GC). METHOD: Thermogelling, mucoadhesive, mechanical, and viscoelastic properties of GC and the new formulation were evaluated using rheometry. In vitro release profile and the bioactivity of P4 were determined using vaginal fluid simulant (VFS) pH 4.2, and PR-reporter gene assay, respectively. In vitro safety of the formulations was tested using (VK2/E6E7) vaginal epithelial cell line and Lactobacillus Crispatus. Finally, in vivo safety and the efficacy of this formulation were evaluated using an endometrial hypoplasia mouse model. RESULTS: Results shows the aqueous solution of 5%; (w/v) GC loaded with 0.1%; (w/v) P4 prepared in pH 4.2, (GC-P4), forms a thermosensitive mucoadhesive hydrogel and can maintain stable physical properties at 37 °C. GC-P4 gel release 50% of P4 in 4 h after exposure to VFS, and no significant decrease in % viability of VK2/E6E7 or Lactobacillus was found after exposure to 5% GC or GC-P4. GC-P4 does not exhibit obvious toxicities to vaginal tissue in vivo even after repeated application. Efficacy studies indicated that GC-P4 was capable of preventing the progression of simple endometrial hyperplasia (SEH) to complex atypical endometrial hyperplasia (CAEH) in vivo. CONCLUSIONS: Results indicates that GC-P4 retains many characteristics for an effective vaginal delivery system for P4. Therefore we believe that GC-P4 formulation is a promising alternative to current vaginal P4 formulation.

An immunocompetent, orthotopic mouse model of epithelial ovarian cancer utilizing tissue engineered tumor cell sheets.

Despite the development of a myriad of anticancer drugs that appeared promising in preclinical ovarian cancer animal models, they failed to predict efficacy in clinical testing. To improve the accuracy of preclinical testing of efficacy and toxicity, including pharmacokinetic and pharmacodynamic evaluations, a novel animal model was developed and characterized. In this study, murine ID8 (epithelial ovarian cancer [EOC]) cells as injected cell suspensions (ICS) and as intact cultured monolayer cell sheets (CS) were injected or surgically grafted, respectively, into the left ovarian bursa of 6-8 week-old, female C57BL/6 black mice and evaluated at 8 and 12 weeks after engraftment. Tumor volumes at 8 weeks were as follows: 30.712 ± 18.800 mm(3) versus 55.837 ± 10.711 mm(3) for ICS and CS, respectively, p = 0.0990 (n = 5). At 12 weeks, tumor volumes were 128.129 ± 44.018 mm(3) versus 283.953 ± 71.676 mm(3) for ICS and CS, respectively, p = 0.0112 (n = 5). The ovarian weights at 8 and 12 weeks were 0.02138 ± 0.01038 g versus 0.04954 ± 0.00667 g for ICS and CS, respectively (8 weeks), p = 0.00602 (n = 5); and 0.10594 ± 0.03043 g versus 0.39264 ± 0.09271 g for ICS and CS, respectively (12 weeks), p = 0.0008 (n = 5). These results confirm a significant accelerated tumorigenesis in CS-derived tumors compared with ICS-derived tumors when measured by tumor volume/time and ovarian weight/time. Furthermore, the CS-derived tumors closely replicated the metastatic spread found in human EOC and histopathological identity with the primary tumor of origin.

Ultrasound-assisted siRNA delivery via arginine-grafted bioreducible polymer and microbubbles targeting VEGF for ovarian cancer treatment.

The major drawback hampering siRNA therapies from being more widely accepted in clinical practice is its insufficient accumulation at the target site mainly due to poor cellular uptake and rapid degradation in serum. Therefore, we designed a novel polymeric siRNA carrier system, which would withstand serum-containing environments and tested its performance in vitro as well as in vivo. Delivering siRNA with a system combining an arginine-grafted bioreducible polymer (ABP), microbubbles (MBs), and ultrasound technology (US) we were able to synergize the advantages each delivery system owns individually, and created our innovative siRNA-ABP-MB (SAM) complexes. SAM complexes show significantly higher siRNA uptake and VEGF protein knockdown in vitro with serum-containing media when compared to naked siRNA, and 25k-branched-polyethylenimine (bPEI) representing the current standard in nonviral gene therapy. SAM complexes activated by US are also able to improve siRNA uptake in tumor tissue resulting in decelerating tumor growth in vivo.

Mucoadhesive hybrid gel improves intraperitoneal platinum delivery.

A leading cause of death and suffering in patients with abdominal or pelvic malignancies is progression of peritoneal surface disease. Changes in the use of chemotherapy have shown significant survival benefits for intraperitoneal or combined intraperitoneal and intravenous treatment following optimal surgical cytoreduction. However, broader clinical use of intraperitoneal therapy has not reached its full potential due to limited efficacy, accessibility and nonspecific toxicity. To overcome these problems, we developed a mucoadhesive hybrid gel (HG) for a local, intraperitoneal drug delivery. In vivo studies confirmed reliable adherence and residence of the gel to the peritoneal sidewall for at least 72 h exhibiting no signs of tissue toxicity. Functionally active CDDP was released from HG within 2h and was equal to free CDDP in vitro. Moreover, intraperitoneal application of HG-CDDP significantly enhanced CDDP accumulation in the genomic DNA of peritoneal tissues compared to the same CDDP dose administered intravenously. These findings indicate the potential application of this hybrid gel as a mucoadhesive drug carrier amendable to use for intraperitoneal drug delivery and possible expansion for use on other mucosal surfaces of the female reproductive tract.

Characterization and evaluation of pre-clinical suitability of a syngeneic orthotopic mouse ovarian cancer model.

BACKGROUND/AIM: To develop and characterize the pre-clinical suitability of a syngeneic mouse epithelial ovarian cancer model in immunocompetent hosts. MATERIALS AND METHODS: ID8 mouse ovarian surface epithelium cells were implanted into the left ovarian bursa of C57BL/6 mice. Using conventional as well as ultrasound-based techniques and histopathological analysis, the tumor weights, volumes, metastases, ascites and vascularity were observed over a period of 16 weeks. RESULTS: Ovarian weights and volume increased 12- and 7-fold, respectively. Ultrasound measurements of ovarian ID8 tumors correlated with the actual size obtained following surgical excision. Ascites and metastasis were first observed at 12 weeks post-orthotopic implantation. Histopathological analysis indicated similarities between orthotopically-generated ovarian tumors and human ovarian tumors. However, there was less evidence of angiogenesis in this animal model. CONCLUSION: The development of this mouse model closely replicates characteristics seen in human ovarian cancer with feasibility of using ultrasound to assess tumor formation, progression and vascularization.

Preparation and characterization of glycol chitin as a new thermogelling polymer for biomedical applications.

In this study, a new thermo-sensitive polymer, glycol chitin, was synthesized by controlled N-acetylation of glycol chitosan and evaluated as a thermogelling system. The physico-chemical properties of glycol chitins with different degrees of acetylation (DA) were investigated in terms of degradation, cytotoxicity, rheological properties, and in vitro and in vivo gel formation. Aqueous solutions of glycol chitins were flowable freely at room temperature but quickly became a durable gel at body temperature. Thermo-reversible sol-gel transition properties were observed with fast gelation kinetics. Glycol chitins with higher DA showed faster degradation in the presence of lysozyme. They exhibited no significant biological toxicity against human cell lines. An anti-cancer drug, doxorubicin, could be incorporated into the hydrogel by a simple mixing process and released in a sustained pattern over 13 days. Our findings suggest that glycol chitins could be useful as a new thermogelling biomaterial for drug delivery and injectable tissue engineering.

Synthesis and evaluation of a backbone biodegradable multiblock HPMA copolymer nanocarrier for the systemic delivery of paclitaxel.

The performance and safety of current antineoplastic agents, particularly water-insoluble drugs, are still far from satisfactory. For example, the currently widely used Cremophor EL®-based paclitaxel (PTX) formulation exhibits pharmacokinetic concerns and severe side effects. Thus, the concept of a biodegradable polymeric drug-delivery system, which can significantly improve therapeutic efficacy and reduce side effects is advocated. The present work aims to develop a new-generation of long-circulating, biodegradable carriers for effective delivery of PTX. First, a multiblock backbone biodegradable N-(2-hydroxypropyl)methacrylamide(HPMA) copolymer-PTX conjugate (mP-PTX) with molecular weight (Mw) of 335 kDa was synthesized by RAFT (reversible addition-fragmentation chain transfer) copolymerization, followed by chain extension. In vitro studies on human ovarian carcinoma A2780 cells were carried out to investigate the cytotoxicity of free PTX, HPMA copolymer-PTX conjugate with Mw of 48 kDa (P-PTX), and mP-PTX. The experiments demonstrated that mP-PTX has a similar cytotoxic effect against A2780 cells as free PTX and P-PTX. To further compare the behavior of this new biodegradable conjugate (mP-PTX) with free PTX and P-PTX in vivo evaluation was performed using female nu/nu mice bearing orthotopic A2780 ovarian tumors. Pharmacokinetics study showed that high Mw mP-PTX was cleared more slowly from the blood than commercial PTX formulation and low Mw P-PTX. SPECT/CT imaging and biodistribution studies demonstrated biodegradability as well as elimination of mP-PTX from the body. The tumors in the mP-PTX treated group grew more slowly than those treated with saline, free PTX, and P-PTX (single dose at 20 mg PTX/kg equivalent). Moreover, mice treated with mP-PTX had no obvious ascites and body-weight loss. Histological analysis indicated that mP-PTX had no toxicity in liver and spleen, but induced massive cell death in the tumor. In summary, this biodegradable drug delivery system has a great potential to improve performance and safety of current antineoplastic agents.