Intratumoral Drug Concentration Research Articles

Abstract A060: Targeting DRD2 dysregulation in recurrent glioblastoma with imipridone ONC201: predictive and pharmacodynamic clinical biomarker analyses

Abstract Background: ONC201, an imipridone that is a selective antagonist of the G protein-coupled receptors dopamine receptor D2 (DRD2) and D3 (DRD3), has exhibited biologic activity and an exceptional safety profile in a phase II study in bevacizumab-naïve recurrent glioblastoma (Arrillaga et a.l, 2017). Single-agent ONC201 efficacy has been observed in preclinical glioblastoma models in addition to robust penetrance of the blood-brain barrier (Allen et al., 2013). DRD2 antagonism induces tumor cell apoptosis via the same signaling pathways affected by ONC201. In addition, DRD2 is expressed on NK and other immune cells and DRD2 antagonism can induce their activation. Methods: Cell viability assays were performed with ONC201 in >1000 Genomic of Drug Sensitivity in Cancer (GDSC) cell lines and NCI60. Immunohistochemistry staining of DRD2/DRD5 was performed in glioblastoma tissue microarrays and archival tumor tissues. Whole exome sequencing was performed in RKO cells with acquired resistance to ONC201. DRD5 wild-type and mutant constructs were generated for overexpression studies. ELISA was used to quantitate serum prolactin and immune effector (perforin) levels. Intratumoral drug concentrations were evaluated by LC-MS assays conducted on glioblastoma tissue resected from patients following the second dose of 625mg ONC201. Results: Evaluation of ONC201 in GDSC cell lines confirmed broad anticancer efficacy with high sensitivity (~1-3 µM) in human brain cancer. The Cancer Genome Atlas (TCGA) revealed that DRD2 is highly expressed in glioblastoma relative to other dopamine receptors and that genetic aberrations are rare. High expression of DRD2 occurred in primary, rather than secondary, glioblastoma and was associated with a poor prognosis. Immunohistochemistry of tissue microarrays revealed DRD2 overexpression in glioblastoma relative to normal brain. A linear correlation between DRD2 mRNA and ONC201 GI50 was observed among glioblastoma cell lines in the NCI60 panel. Interestingly, expression of DRD5, a D1-like dopamine receptor that counteracts DRD2 signaling, was significantly inversely correlated with ONC201 potency in the NCI60 and GDSC datasets (P <.05). Furthermore, a missense DRD5 mutation was identified in cancer cells with acquired resistance to ONC201. Resistance could be recapitulated with overexpression of the mutant or wild-type DRD5 gene. A significant induction of serum prolactin, a surrogate biomarker of target engagement, was detected upon ONC201 administration to recurrent glioblastoma patients. Intratumoral drug concentrations surpassed therapeutic levels, ranging from ~0.6-10µM at 24 hours post-dose. Immune effector levels in the serum correlated with the kinetics of a durable objective response observed in a patient with an H3.3 K27M glioma. Among the 15 available archival tumor tissue specimens, all had expression of DRD2 and 8/17 patients had low expression of DRD5. Patients with PFS>5 month had no detectable expression of DRD5, unlike those with PFS<5 months. In addition, 4/8 DRD2+DRD5- and 0/7 DRD2+DRD5+ patients are still alive with a median follow-up of 47.4 weeks. Conclusion: The dopamine receptor pathway is a novel therapeutic target that is dysregulated in glioblastoma and provides predictive and pharmacodynamic biomarkers of tumor sensitivity to ONC201. Citation Format: Varun Vijay Prabhu, Neel Madhukar, C. Leah B. Kline, Rohinton Tarapore, Wafik El-Deiry, Olivier Elemento, Faye Doherty, Alexander VanEngelenburg, Jessica Durrant, Andrew Zloza, Cyril Benes, Isabel Arrillaga, Wolfgang Oster, Joshua E. Allen. Targeting DRD2 dysregulation in recurrent glioblastoma with imipridone ONC201: predictive and pharmacodynamic clinical biomarker analyses [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A060.

Methods and Study Designs for Characterizing the Pharmacokinetics and Pharmacodynamics of Carrier-Mediated Agents.

Major advances in carrier-mediated agents (CMAs), which include nanoparticles, nanosomes, and conjugates, have revolutionized drug delivery capabilities over the past decade. While providing numerous advantages, such as greater solubility, duration of exposure, and delivery to the site of action over their small molecule counterparts, there is substantial variability in systemic clearance and distribution, tumor delivery, and pharmacologic effects (efficacy and toxicity) of these agents. In this chapter, we focus on the analytical and phenotypic methods required to design a study that characterizes the pharmacokinetics (PK) and pharmacodynamics (PD) of all forms of these nanoparticle-based drug agents. These methods include separation of encapsulated and released drugs, ultrafiltration for measurement of non-protein bound active drug, microdialysis to measure intra-tumor drug concentrations, immunomagnetic separation and flow cytometry for sorting cell types, and evaluation of spatial distribution of drug forms relative to tissue architecture by mass spectrometry imaging and immunohistochemistry.

Application of 3D Mass Spectrometry Imaging to TKIs

Mass spectrometry imaging (MSI) allows visualization of endogenous and exogenous compound in tissue sections based on its molecular mass. The 3D reconstruction by MSI provides a more informative description of the tumor drug distribution compared to the high-performance liquid chromatography method, highlighting the heterogeneity of intratumor drug concentration. This additional information can be important in understanding chemoresistance to target agents. Here, we present the 3D visualization of the tyrosine kinase inhibitor (TKI), imatinib, in a xenograft model of resistant malignant pleural mesothelioma.

18F-Labeled Carboplatin Derivative for PET Imaging of Platinum Drug Distribution.

Increasing evidence indicates that reduced intracellular drug accumulation is the parameter most consistently associated with platinum drug resistance, emphasizing the need to directly measure the intratumor drug concentration. In the era of precision medicine and with the advent of powerful imaging and proteomics technologies, there is an opportunity to better understand drug resistance by exploiting these techniques to provide new knowledge on drug-target interactions. Here, we contribute to this endeavor by reporting on the development of an 18F-labeled carboplatin derivative (18F-FCP) that has the potential to image drug uptake and retention, including intratumoral distribution, by PET. Methods: Fluorinated carboplatin (19F-FCP) was synthesized using 19F-labeled 2-(5-fluoro-pentyl)-2-methyl malonic acid (19F-FPMA) as the labeling agent to coordinate with the cisplatin-aqua complex. It was then used to treat cell lines and compared with cisplatin and carboplatin at different concentrations. Manual radiosynthesis and characterization of 18F-FCP were performed using 18F-FPMA for coordination with the cisplatin-aqua complex. Automated radiosynthesis of 18F-FCP was optimized on the basis of manual synthesis procedures. The stability of 18F-FCP was verified using high-performance liquid chromatography. 18F-FCP was evaluated using ex vivo biodistribution and in vivo PET imaging in non-tumor-bearing animals as well as in KB-3-1 and COLO-205 tumor xenograft-bearing nude mice. Results: In vitro cytotoxicity studies demonstrated that 19F-FCP has an antitumor activity profile similar to that of the parent drug carboplatin. In vivo plasma and urine stability analysis showed intact 18F-FCP at 24 h after injection. PET imaging and biodistribution studies showed fast clearance from blood and major accumulation in the kidneys, indicating substantial renal clearance of 18F-FCP. Using 18F-FCP PET, we could image and identify the intratumor drug profile. Conclusion: Our results demonstrated that 19F-FCP, like carboplatin, retains antitumor activity in various cell lines. 18F-FCP could be a useful imaging tool for measuring the intratumor drug distribution. This strategy of using a new therapeutic carboplatin derivative to quantify and track platinum drugs in tumors using PET has the potential to translate into a clinically useful imaging tool for individual patients.

Performance of Doxorubicin-Conjugated Gold Nanoparticles: Regulation of Drug Location

Drug-conjugated gold nanoparticles (GNPs), which are generally constructed with many molecules of thiol-terminated polyethylene glycol (PEG)-drug decorated on their surfaces via a thiol-Au covalent bond, are promising and efficient nanoprodrugs. However, because of the exposure of the hydrophobic drug molecules on the surface of the conjugate, in vivo stability, opsonization, and subsequent inefficient therapy become the main issues of this system. To solve these problems without complicating the structures of gold conjugates, herein we propose a method to change the relative position of PEG and the drug. A novel gold conjugate (GNP-NHN═Dox-mPEG) with doxorubicin (Dox) shielded by PEGylation on the surface of GNPs is designed. It demonstrates improved solubility, stability, and dispersion and achieves a two-step stimulus-responsive drug release in response to an acidic environment in lysosomes and then esterase in the cytoplasm. This unique manner of release enables the cytoplasm to act as a reservoir for sustained drug delivery into the nucleus to improve antitumor efficacy in vivo. The intratumoral drug concentrations of the conjugate reach 14.4 ± 1.4 μg/g at 8 h, a two-fold increase in the drug concentration compared with that of the doxorubicin hydrochloride group. This molecular design and regulation approach is facile but important in modulating the in vivo performance of nanovehicles and demonstrates its vital potential in developing effective nanoparticle-based drug delivery agents.

Targeted delivery of paclitaxel and doxorubicin to cancer xenografts via the nanoparticle of nano-diamino-tetrac.

The tetraiodothyroacetic acid (tetrac) component of nano-diamino-tetrac (NDAT) is chemically bonded via a linker to a poly(lactic-co-glycolic acid) nanoparticle that can encapsulate anticancer drugs. Tetrac targets the plasma membrane of cancer cells at a receptor on the extracellular domain of integrin αvβ3. In this study, we evaluate the efficiency of NDAT delivery of paclitaxel and doxorubicin to, respectively, pancreatic and breast cancer orthotopic nude mouse xenografts. Intra-tumoral drug concentrations were 5-fold (paclitaxel; P<0.001) and 2.3-fold (doxorubicin; P<0.01) higher than with conventional systemic drug administration. Tumor volume reductions reflected enhanced xenograft drug uptake. Cell viability was estimated by bioluminescent signaling in pancreatic tumors and confirmed an increased paclitaxel effect with drug delivery by NDAT. NDAT delivery of chemotherapy increases drug delivery to cancers and increases drug efficacy.

Targeted delivery of cisplatin to tumor xenografts via the nanoparticle component of nano-diamino-tetrac.

Nano-diamino-tetrac (NDAT) targets a receptor on integrin αvβ3; αvβ3 is generously expressed by cancer cells and dividing endothelial cells and to a small extent by nonmalignant cells. The tetrac (tetraiodothyroacetic acid) of NDAT is covalently bound to a poly(lactic-co-glycolic acid) nanoparticle that encapsulates anticancer drugs. We report NDAT delivery efficiency of cisplatin to agent-susceptible urinary bladder cancer xenografts. Cisplatin-loaded NDAT (NDAT-cisplatin) was administered to xenograft-bearing nude mice. Tumor size response and drug content were measured. Intratumoral drug concentration was up to fivefold higher (p < 0.001) in NDAT-cisplatin-exposed lesions than with conventional systemic administration. Tumor volume reduction achieved was NDAT-cisplatin > NDAT without cisplatin > cisplatin alone. NDAT markedly enhances cisplatin delivery to urinary bladder cancer xenografts and increases drug efficacy.

Bioinspired peptosomes with programmed stimuli-responses for sequential drug release and high-performance anticancer therapy.

Combination therapy with enhanced therapeutic and antimetastatic efficacy has become promising for cancer treatment. There is an urgent need to design a co-delivery system to sequentially release the drug pair at desired locations that can increase the intra-tumoral drug concentration and reduce the side effects. Inspired by virus architecture and function, herein, we developed a peptosome (PS)-based co-delivery system, PePm/PS/Curcumin (Cur), for the sequential release of the therapeutic peptide Pe and chemodrug Cur. PS was formed by the self-assembly of amphiphilic α-lactalbumin peptides obtained from enzymatic partial hydrolysis. Then, PS was self-cross-linked with disulfide bonds utilizing their endogenous thiol groups. The system is responsive to multiple tumor microenvironments and releases the drugs at specific tumor locations. First, after PS accumulation in tumor tissue via the EPR effect, the linkage peptide Pm in PS can be cleaved by matrix metalloproteinases (MMP) enzymatic hydrolysis. Pe can stay on the cell surface and antagonize the ErbB-2 receptor expression on the tumor cells. Moreover, the positively charged nature of remaining Mal-PS/Cur facilitates tumor cell internalization and induces a subsequent proton-sponge effect for lysosomal escape. Finally, Cur is released in the cytoplasm via a reduction-induced PS disassembly due to the high level of intracellular GSH. Both the in vitro and in vivo results exhibited an enhanced antitumor and antimetastatic efficacy of this system.

Limited Tumor Tissue Drug Penetration Contributes to Primary Resistance against Angiogenesis Inhibitors.

Resistance mechanisms against antiangiogenic drugs are unclear. Here, we correlated the antitumor and antivascular properties of five different antiangiogenic receptor tyrosine kinase inhibitors (RTKIs) (motesanib, pazopanib, sorafenib, sunitinib, vatalanib) with their intratumoral distribution data obtained by matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI). In the first mouse model, only sunitinib exhibited broad-spectrum antivascular and antitumor activities by simultaneously suppressing vascular endothelial growth factor receptor-2 (VEGFR2) and desmin expression, and by increasing intratumoral hypoxia and inhibiting both tumor growth and vascularisation significantly. Importantly, the highest and most homogeneous intratumoral drug concentrations have been found in sunitinib-treated animals. In another animal model, where - in contrast to the first model - vatalanib was detectable at homogeneously high intratumoral concentrations, the drug significantly reduced tumor growth and angiogenesis. In conclusion, the tumor tissue penetration and thus the antiangiogenic and antitumor potential of antiangiogenic RTKIs vary among the tumor models and our study demonstrates the potential of MALDI-MSI to predict the efficacy of unlabelled small molecule antiangiogenic drugs in malignant tissue. Our approach is thus a major technical and preclinical advance demonstrating that primary resistance to angiogenesis inhibitors involves limited tumor tissue drug penetration. We also conclude that MALDI-MSI may significantly contribute to the improvement of antivascular cancer therapies.

Implantable chemotherapy-loaded silk protein materials for neuroblastoma treatment.

Neuroblastoma is the most common extracranial childhood solid tumor. Treatment of high risk tumors require intense multicycle chemotherapies, resulting in short- and long-term toxicities. Here, we present treatment of an orthotopic neuroblastoma mouse model, with silk fibroin materials loaded with vincristine, doxorubicin or the combination as a intratumoral, sustained release system. The materials, loaded with vincristine with or without doxorubicin, significantly decreased neuroblastoma tumor growth compared to materials loaded without drug or doxorubicin only as well as intravenous (IV) drug treatment. The intratumoral drug concentration was significantly higher with intratumoral delivery versus IV. Furthermore, intratumor delivery decreased the maximum plasma concentration compared to IV delivery, reducing systemic exposure and possibly reduing long-term side effects of chemotherapy exposure. Histopathologically, tumors with remission periods >25 days before recurrence transformed from a "small-round-blue cell" (SBRC) to predominantly "large cell" neuroblastoma (LCN) histopathology, a more aggressive tumor subtype with unfavorable clinical outcomes. These results show that intratumoral chemotherapy delivery may be a treatment strategy for pediatric neuroblastoma, potentially translatable to other focal tumors types. Furthermore, this treatment modality allows for a clinically relevant mouse model of tumor transformation that may be used for studying the phenotypical tumor recurrence and developing more effective treatment strategies for recurrent tumors.

Pharmacokinetic/pharmacodynamic modeling of etoposide tumor growth inhibitory effect in Walker-256 tumor-bearing rat model using free intratumoral drug concentrations

The purpose of this study was to establish a population pharmacokinetic/pharmacodynamic (PK/PD) model linking etoposide free tumor and total plasma concentrations to the inhibition of solid tumor growth in rats. Walker-256 tumor cells were inoculated subcutaneously in the right flank of Wistar rats, which were randomly divided in control and two treated groups that received etoposide 5 or 10mg/kg i.v. bolus every day for 8 and 4days, respectively, and tumor volume was monitored daily for 30days. The plasma and intratumoral concentrations-time profiles were obtained from a previous study and were modeled by a four-compartment population pharmacokinetic (popPK) model. PK/PD analysis was conducted using MONOLIX v.4.3.3 on average data and by mean of a nonlinear mixed-effect model. PK/PD data were analyzed using a modification of Simeoni Tumor Growth Inhibition (TGI) model by introduction of an Emax function to take into account the concentration dependency of k2variable parameter (variable potency). The Simeoni TGI-Emax model was capable to fit schedule-dependent antitumor effects using the tumor growth curves from the control and two different administered schedules. The PK/PD model was capable of describing the tumor growth inhibition using total plasma or free tumor concentrations, resulting in higher k2max (maximal potency) for free concentrations (25.8mL·μg−1·day−1 - intratumoral vs. 12.6mL·μg−1·day−1 total plasma). These findings indicate that the plasma concentration may not be a good surrogate for pharmacologically active free tumor concentrations, emphasizing the importance of knowing drug tumor penetration to choose the best antitumor therapy.

The release of Doxorubicin from liposomes monitored by MRI and triggered by a combination of US stimuli led to a complete tumor regression in a breast cancer mouse model

The work aimed at developing a novel MRI-based theranostic protocol for improving the anticancer efficacy of a Doxil-like liposomal formulation. The goal was achieved stimulating the intratumor release of the drug from the nanocarrier and favoring its diffusion in the lesion by the sequential application of low-intensity pulsed ultrasound. The protocol was tested on mice bearing a syngeneic breast cancer model. The combination of acoustic waves with different characteristics allowed for: i) the release of the drug and the co-encapsulated MRI agent (Gadoteridol) from the liposomes in the vessels of the tumor region, and ii) the extravasation of the released material, as well as intact liposomes, in the tumor stroma. The MR-T1 contrast enhancement measured in the tumor reported on the delivery and US-triggered release of Doxorubicin. The developed protocol resulted in a marked increase in the intratumor drug concentration that, in turn, led to the complete regression of the lesion. The protocol has a good clinical translatability because all the components of the theranostic agent (Doxorubicin, liposomes, Gadoteridol) are approved for human use.

Understanding taxanes in prostate cancer; importance of intratumoral drug accumulation.

Resistance to docetaxel is common in metastatic castration-resistant prostate cancer (mCRPC) and may be caused by sub-therapeutic intratumoral drug concentrations. Cabazitaxel demonstrated survival benefit in docetaxel-pretreated and docetaxel-refractory patients. In this study, we investigated whether the superior antitumor activity of cabazitaxel in mCRPC is explained by higher intratumoral cabazitaxel levels. Since recent studies suggest a reduced efficacy of docetaxel following treatment with novel androgen receptor (AR)-targeted agents, we also investigated taxane efficacy in an enzalutamide-resistant tumor model. Intratumoral concentrations of docetaxel and cabazitaxel were correlated with antitumor activity in docetaxel-naïve, docetaxel-resistant, and enzalutamide-resistant patient-derived xenografts (PDXs) of prostate cancer. Intratumoral drug levels were negatively related to intrinsic and acquired resistance to docetaxel. Also, the observed stronger antitumor activity of cabazitaxel was associated with increased cumulative exposure and higher intratumoral of cabazitaxel concentrations in all PDXs. The superior antitumor activity of cabazitaxel in docetaxel- and enzalutamide-resistant tumors can be partly attributed to higher intratumoral drug concentrations. Especially for patients who are intrinsically resistant to docetaxel resulting from suboptimal intratumoral docetaxel concentrations, cabazitaxel may be the preferred chemotherapeutic agent. Prostate 76:927-936, 2016. © 2016 Wiley Periodicals, Inc.

Abstract P4-14-24: Optimization of intermittent high dose lapatinib administration with or without capecitabine: A rational approach to drug dosing and scheduling using Norton-Simon modeling

Abstract Background: Systemic treatment of central nervous system (CNS) metastases remains a challenge partially due to poor drug penetration. Lapatinib and capecitabine are drugs with modest efficacy in treatment of brain metastases from HER2-positive (+) breast cancer (BC) and were shown to cross the blood-tumor barrier in clinical craniotomy specimens (Lin N et al., CCR 2009, Morikawa A et al., Neuro Oncol 2015). However, intratumoral drug concentrations observed were sub-optimal and heterogeneous. Administration of shorter-duration, high dose tyrosine kinase inhibitor is proposed as a way to improve efficacy and tolerability based on Norton-Simon modeling and drug exposure in the CNS (Traina T et al., JCO 2008, Grommes C et al., Neuro Oncol 2011, Chien AJ et al., J Clin Oncol 2014) . In this study, we examined optimization of high dose lapatinib administration with or without capecitabine to inform the design of a phase I trial for BC patients with HER2+ CNS metastases. Methods: Mice bearing BT-474 BC xenograft tumors were treated with various lapatinib doses and schedules. A standard continuous daily dose (100mg/kg) was compared to various intermittent dosing schedules (at 100mg/kg, 400mg/kg, and 800mg/kg). In addition, high dose lapatinib (800mg/kg) was administered with capecitabine either concurrently or in tandem. Xenografts were treated when tumors reached 100mm3. Tumor volumes were evaluated for antitumor efficacy, and mice weights were measured for toxicity. Significance testing for between-group comparisons was conducted using a mixed effect model for repeated measures. Results: Intermittent schedules of lapatinib at 100mg/kg given as 3 days on/11 days off (3/11), 5 days on/9 days off (5/9), and 7 days on/7days off (7/7) had a similar efficacy in tumor control: percent change in tumor volume of 225% (7/7), 222% (5/9), and 223% (3/11) (NS). Therefore, the 3 days on (with 4 days off or 11 days off ) schedule was subsequently chosen to evaluate for tolerability and antitumor efficacy of higher lapatinib dose. The 3 days on/4 days off (3/4) group at 800mg/kg demonstrated the highest tumor reduction (-69%) compared to the daily continuous dosing group (-18%) (p=0.04), but a trend toward higher toxicity was observed (p=0.12). Evaluation of concurrent vs. tandem administration of capecitabine with lapatinib at 800mg/kg given in 3 days on/11 days off was conducted. The concurrent treatment was discontinued early due to high toxicity. However, tandem administration of capecitabine with high dose lapatinib was tolerable without a significant difference in weight changes (p=0.62). Conclusions: The intermittent schedule allows delivery of high dose lapatinib, which has better anti-tumor activity than standard continuous dosing. If given intermittently, high dose lapatinib is tolerable, even with capecitabine if given in tandem/sequence. Based on the result of these experiments, a phase I trial of high dose lapatinib using 3 days on/11 days off schedule in tandem with capecitabine is currently proposed for treatment of HER2-positive BC patient with CNS metastases. Citation Format: Morikawa A, De Stanchina E, Patil S, Chandarlapaty S, Li BT, Norton L, Seidman AD. Optimization of intermittent high dose lapatinib administration with or without capecitabine: A rational approach to drug dosing and scheduling using Norton-Simon modeling. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-14-24.

Two-Step Delivery: Exploiting the Partition Coefficient Concept to Increase Intratumoral Paclitaxel Concentrations In vivo Using Responsive Nanoparticles

Drug dose, high local target tissue concentration, and prolonged duration of exposure are essential criteria in achieving optimal drug performance. However, systemically delivered drugs often fail to effectively address these factors with only fractions of the injected dose reaching the target tissue. This is especially evident in the treatment of peritoneal cancers, including mesothelioma, ovarian, and pancreatic cancer, which regularly employ regimens of intravenous and/or intraperitoneal chemotherapy (e.g., gemcitabine, cisplatin, pemetrexed, and paclitaxel) with limited results. Here, we show that a “two-step” nanoparticle (NP) delivery system may address this limitation. This two-step approach involves the separate administration of NP and drug where, first, the NP localizes to tumor. Second, subsequent administration of drug then rapidly concentrates into the NP already stationed within the target tissue. This two-step method results in a greater than 5-fold increase in intratumoral drug concentrations compared to conventional “drug-alone” administration. These results suggest that this unique two-step delivery may provide a novel method for increasing drug concentrations in target tissues.

Preparation, characterization, and efficacy of thermosensitive liposomes containing paclitaxel

To increase the anti-tumor activity of paclitaxel (PTX), novel temperature-sensitive liposomes loading paclitaxel (PTX-TSL) were developed. In vitro, characteristics of PTX-TSL were evaluated. The mean particle diameter was about 100 nm, and the entrapment efficiency was larger than 95%. The phase-transition temperature of PTX-TSL determined by differential scanning calorimetry was about 42 °C. The result of in vitro drug release from PTX-TSL illustrated that release rate at 37 °C was obviously lower than that at 42 °C. Stability data indicated that the liposome was physically and chemically stable for at least 3 months at −20 °C. In vivo study, after three injections with hyperthermia in the xenograft lung tumor model, PTX-TSL showed distinguished tumor growth suppression, compared with non-temperature-sensitive liposome and free drug. The results of intratumoral drug concentration indicated that PTX-TSL combined with hyperthermia delivered more paxlitaxel into the tumor location than the other two paxlitaxel formulations. In summary, PTX-TSL combined with hyperthermia significantly inhibited tumor growth, due to the increased targeting efficiency of PTX to tumor tissues. Such approach may enhance the delivery efficiency of chemotherapeutics into solid tumors.

Dual-targeting nanocarrier system based on thermosensitive liposomes and gold nanorods for cancer thermo-chemotherapy

The primary challenge of cancer therapy was the failure of most chemotherapeutics to accumulate in the tumors, additionally causing serious systemic side effects. We designed a tumor-targeting accumulated and locally triggered-release nanocarrier system to increase the intratumoral drug concentration and thus the efficacy of chemotherapy, based on gold nanorods (GNRs) and thermosensitive liposomes (TSLs). PEGylated GNRs could not only make nanocarriers to co-accumulate in tumors depending on enhanced permeability and retention (EPR) effect, but also generated heat locally under near-infrared (NIR) stimulation. CO2 bubbles were generated by the encapsulated ammonium bicarbonate (ABC) under hyperthermia, thus the co-encapsulated drug was released and local drug concentration was increased along with the disintegration of liposomal membrane. On the other hand, this dual-targeting system prevented the drug leakage in blood circulation or other organs while facilitated most of the active agents delivered to tumors. In vitro and in vivo experiments revealed high cytotoxicity and good affinity of HTSL to MDA-MB-435 cells when used synergistically with GNRs, but low toxicity to normal cells at the same condition. When combined with thermotherapy, the smart nanocarrier system held significant promise for future cancer treatment for their markedly improved therapeutic efficacy and decreased systemic toxicity.

Abstract 4182: Gemcitabine triggers angiogenesis-promoting molecular signals in pancreatic cancer cells: Therapeutic implications

Abstract Pancreatic tumor microenvironment (TME) is characterized by poor tumor vasculature and extensive desmoplasia that together contribute to poor response to chemotherapy. It was recently shown that targeting of TME to inhibit desmoplastic reaction in a mouse model of pancreatic cancer resulted in increased microvessel density and intratumoral drug concentration, leading to improved therapeutic response. This approach; however, failed to generate a favorable response in a clinical trial. In that regard, we have previously demonstrated that gemcitabine-treatment of pancreatic cancer cells induces CXCR4 expression in a counter-defense mechanism and promotes pancreatic tumor cell invasiveness. The goal of present study was to examine the effect of chemotherapy on endothelial cell growth and migration. Pancreatic cancer cells were treated with gemcitabine or vehicle for 8 h and subsequently incubated in fresh low serum-containing media for next 48 h. Conditioned media was collected from vehicle- (V-CM) and gemcitabine-treated (Gem-CM) pancreatic cancer cells and used for the treatment of human umbilical vein endothelial cells (HUVEC). The data demonstrated stimulatory effects of Gem-CM on endothelial cell proliferation, migration, invasion and capillary-like structure (CLS) formation. Expression analysis of vehicle- and gemcitabine-treated pancreatic cancer cells and their conditioned-media revealed an upregulation of CXCL8/IL8, which is a known regulator of angiogenesis. Currently, we are investigating whether IL8 mediates the effect of Gem-CM on endothelial cells. Together, our findings suggest that gemcitabine triggers angiogenesis-promoting molecular signals in pancreatic cancer cells, which, in light of our previous observations, may hold important clinical and translational significance. Citation Format: Mohammad Aslam Khan, Sanjeev K. Srivastava, Arun Bhardwaj, Seema Singh, James E. Carter, Ajay P. Singh. Gemcitabine triggers angiogenesis-promoting molecular signals in pancreatic cancer cells: Therapeutic implications. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4182. doi:10.1158/1538-7445.AM2015-4182

Phase I trial of the HSP-90 inhibitor PU-H71.

2537 Background: PU-H71 (PU) is an HSP-90 inhibitor that can be labeled with 124I without altering its biochemical properties. Intratumoral drug concentration can be calculated based on 124I-PU-H71 (*PU) PET imaging, leading to a surrogate marker of intratumoral pharmacokinetics. Methods: Patients (pts) with previously treated solid tumors, lymphoma and myeloproliferative neoplasms (MPN) on ruxolitinib were eligible. PU was given days 1, 4, 8, 11 each 21 days at escalating dose levels using a Continuous Reassessment Method (CRM). The primary objective was determination of the MTD. Secondary objectives included plasma and intratumoral PKs measured by pre- and on-treatment core needle biopsies (CNB) and by *PU PET imaging. Results: To date, 40 pts have received PU at doses from 10-400mg/m2. 37 are currently evaluable for DLT, and the last 3 pts needed (per CRM) are being enrolled. Five pts experienced DLTs: 1 (of 2) at 400 mg/m2 - grade 3 mucositis; 4 (of 7) at 350 mg/m2 – 1 pt grade 3 AST and ALT, 1 pt gra...

Gemcitabine triggers angiogenesis-promoting molecular signals in pancreatic cancer cells: Therapeutic implications.

Pancreatic tumor microenvironment (TME) is characterized by poor tumor-vasculature and extensive desmoplasia that together contribute to poor response to chemotherapy. It was recently shown that targeting of TME to inhibit desmoplasiatic reaction in a preclinical model resulted in increased microvessel-density and intratumoral drug concentration, leading to improved therapeutic response. This approach, however, failed to generate a favorable response in clinical trial. In that regard, we have previously demonstrated a role of gemcitabine-induced CXCR4 signaling as a counter-defense mechanism, which also promoted invasiveness of pancreatic cancer (PC) cells. Here, we investigated the effect of gemcitabine on endothelial cell phenotype. Gemcitabine-treatment of human-umbilical-vein-endothelial-cells (HUVECs) did not promote the growth of HUVECs; however, it was induced when treated with conditioned media from gemcitabine-treated (Gem-CM) PC cells due to increased cell-cycle progression and apoptotic-resistance. Moreover, treatment of HUVECs with Gem-CM resulted in capillary-like structure (CLS) formation and promoted their ability to migrate and invade through extracellular-matrix. Gemcitabine-treatment of PC cells induced expression of various growth factors/cytokines, including IL-8, which exhibited greatest upregulation. Further, IL-8 depletion in Gem-CM diminished its potency to promote angiogenic phenotypes. Together, these findings suggest an indirect effect of gemcitabine on angiogenesis, which, in light of our previous observations, may hold important clinical significance.