Intratumoral Drug Concentration Research Articles

Docetaxel loaded mPEG-PLA nanoparticles for sarcoma therapy: preparation, characterization, pharmacokinetics, and anti-tumor efficacy

Sarcoma represents one of the most common malignant tumors with poor treatment outcomes and prognosis. Docetaxel (DTX) is acknowledged as one of the most important chemotherapy agents. The aim of this study was to improve the efficacy of docetaxel by incorporation into the mPEG-PLA nanoparticle (DTX NP) for the treatment of sarcoma. The DTX NP was prepared by emulsion solvent diffusion method and the prescription and preparation process were optimized through a single factor experiment. The optimized DTX NP was characterized by drug loading, encapsulation efficiency, drug release, etc. Then, the pharmacokinetics was conducted on rats and tumor-bearing ICR mice. Finally, the anti-tumor efficacy of DTX NP with different dosages was evaluated on tumor-bearing ICR mice. The optimized DTX NP was characterized by around 100 nm sphere nanoparticles, sustained in vitro drug release with no obvious burst drug release. Compared with DTX injection, the AUC of DTX NP increased by 94.7- and 35.1-fold on the rats and tumor-bearing ICR mice models, respectively. Moreover, the intra-tumoral drug concentration increased by 5.40-fold. The tumor inhibition rate of DTX NP reached 94.66%, which was 1.24 times that of DTX injection (76.11%) at the same dosage, and the bodyweight increase rate was also higher than the DTX injection. The study provided a DTX NP, which could significantly improve the bioavailability and therapeutic efficacy of DTX as well as reduced its toxicity. It possessed a certain prospect of application for sarcoma treatment.

DIPG-42. TOWARD MULTIMODALITY THERAPY FOR DIPG/DMG: DEVELOPMENT AND INVESTIGATION OF CRANIOSPINAL IRRADIATION AND CONVECTION-ENHANCED DELIVERY PDX MODELS

BACKGROUNDDiffuse intrinsic pontine glioma (DIPG) and diffuse midline glioma (DMG) are metastatic diseases, as demonstrated by early convection-enhanced delivery (CED) clinical trials in which prolonged local tumor control can sometimes be achieved, but fatal disseminated disease then develops. We hypothesize that improvements in treatment of both focal disease and the entire neuraxis are necessary for long-term survival, and patient-derived xenograft (PDX) models can help advance these efforts.METHODSWe used a BT245 murine orthotopic DIPG PDX model for this work. We developed a protocol and specialized platform to deliver craniospinal irradiation (CSI) with a pontine boost. We separately compared intratumoral drug concentration by CED and intraperitoneal delivery. In our CED model, mice receive gemcitabine 60 ug x1 in 15 ul at 0.5 ul/minute through a stepped catheter design with silica tubing extending 2mm beyond a 27G needle.RESULTSMice receiving CSI (4 Gy x2d) plus boost (4 Gy x2d) showed minimal spinal and brain leptomeningeal metastatic disease by bioluminescence, MRI, and pathology compared to mice receiving radiation to the pons only (4 Gy x4d) or no radiation. CED achieved an intratumoral gemcitabine concentration 50-fold greater than intraperitoneal dosing when controlled for dose.CONCLUSIONSIn a DIPG PDX model, CSI+boost minimizes tumor dissemination compared to focal radiation, and CED achieves clinically significant improvements in intratumoral chemotherapy concentration compared to systemic delivery. Adding these modalities to current treatment could improve both focal and metastatic tumor control, leading to meaningful improvements in survival.

Non-Invasive Measurement of Drug and 2-HG Signals Using 19F and 1H MR Spectroscopy in Brain Tumors Treated with the Mutant IDH1 Inhibitor BAY1436032.

Simple SummaryTargeted therapies are of growing interest to physicians in cancer treatment. These drugs target specific genes and proteins involved in the growth and survival of cancer cells. Brain tumor therapy is complicated by the fact that not all drugs can penetrate the blood brain barrier and reach their target. We explored the non-invasive method, Magnetic Resonance Spectroscopy, for monitoring drug penetration and its effects in live animals bearing brain tumors. We were able to show the presence of the investigated drug in mouse brains and its on-target activity.Background: BAY1436032 is a fluorine-containing inhibitor of the R132X-mutant isocitrate dehydrogenase (mIDH1). It inhibits the mIDH1-mediated production of 2-hydroxyglutarate (2-HG) in glioma cells. We investigated brain penetration of BAY1436032 and its effects using 1H/19F-Magnetic Resonance Spectroscopy (MRS). Methods: 19F-Nuclear Magnetic Resonance (NMR) Spectroscopy was conducted on serum samples from patients treated with BAY1436032 (NCT02746081 trial) in order to analyze 19F spectroscopic signal patterns and concentration-time dynamics of protein-bound inhibitor to facilitate their identification in vivo MRS experiments. Hereafter, 30 mice were implanted with three glioma cell lines (LNT-229, LNT-229 IDH1-R132H, GL261). Mice bearing the IDH-mutated glioma cells received 5 days of treatment with BAY1436032 between baseline and follow-up 1H/19F-MRS scan. All other animals underwent a single scan after BAY1436032 administration. Mouse brains were analyzed by liquid chromatography-mass spectrometry (LC-MS/MS). Results: Evaluation of 1H-MRS data showed a decrease in 2-HG/total creatinine (tCr) ratios from the baseline to post-treatment scans in the mIDH1 murine model. Whole brain concentration of BAY1436032, as determined by 19F-MRS, was similar to total brain tissue concentration determined by Liquid Chromatography with tandem mass spectrometry (LC-MS/MS), with a signal loss due to protein binding. Intratumoral drug concentration, as determined by LC-MS/MS, was not statistically different in models with or without R132X-mutant IDH1 expression. Conclusions: Non-invasive monitoring of mIDH1 inhibition by BAY1436032 in mIDH1 gliomas is feasible.

Structural Optimization and Enhanced Prodrug-Mediated Delivery Overcomes Camptothecin Resistance in High-Risk Solid Tumors.

Camptothecins are potent topoisomerase I inhibitors used to treat high-risk pediatric solid tumors, but they often show poor efficacy due to intrinsic or acquired chemoresistance. Here, we developed a multivalent, polymer-based prodrug of a structurally optimized camptothecin (SN22) designed to overcome key chemoresistance mechanisms. The ability of SN22 vs. SN38 (the active form of irinotecan/CPT-11) to overcome efflux pump-driven drug resistance was tested. Tumor uptake and biodistribution of SN22 as a polymer-based prodrug (PEG-[SN22]4) compared with SN38 was determined. The therapeutic efficacy of PEG-[SN22]4 to CPT-11 was compared in: (i) spontaneous neuroblastomas (NB) in transgenic TH-MYCN mice; (ii) orthotopic xenografts of a drug-resistant NB line SK-N-BE(2)C (mutated TP53); (iii) flank xenografts of a drug-resistant NB-PDX; and (iv) xenografts of Ewing sarcoma and rhabdomyosarcoma. Unlike SN38, SN22 inhibited NB cell growth regardless of ABCG2 expression levels. SN22 prodrug delivery resulted in sustained intratumoral drug concentrations, dramatically higher than those of SN38 at all time points. CPT-11/SN38 treatment had only marginal effects on tumors in transgenic mice, but PEG-[SN22]4 treatment caused complete tumor regression lasting over 6 months (tumor free at necropsy). PEG-[SN22]4 also markedly extended survival of mice with drug-resistant, orthotopic NB and it caused long-term (6+ months) remissions in 80% to 100% of NB and sarcoma xenografts. SN22 administered as a multivalent polymeric prodrug resulted in increased and protracted tumor drug exposure compared with CPT-11, leading to long-term "cures" in NB models of intrinsic or acquired drug resistance, and models of high-risk sarcomas, warranting its further development for clinical trials. SIGNIFICANCE: SN22 is an effective and curative multivalent macromolecular agent in multiple solid tumor mouse models, overcoming common mechanisms of drug resistance with the potential to elicit fewer toxicities than most cancer therapeutics.

Abstract 2273: Selection of first-in-human clinical dose range for the tumor-targeted 4-1BB agonist MP0310 (AMG 506) using a pharmacokinetic/pharmacodynamics modeling approach

Abstract Following the clinical success of checkpoint inhibitors, cancer immunotherapy is rapidly expanding into combination treatments to enhance response rates and duration. Engagement of co-stimulatory molecules from the tumor necrosis factor receptor (TNFR) superfamily, including 4-1BB, may be a promising approach to enhance the benefits of cancer immunotherapy. Agonistic antibodies against the costimulatory receptor 4-1BB (CD137) have been shown to effectively enhance the anti-tumor activity of checkpoint inhibitors and other agents in preclinical animal models. However, the clinical development of 4-1BB agonistic antibodies has met with limited success thus far. Anti-4-1BB monoclonal antibodies have either been reported to cause significant dose-limiting hepatotoxicity or demonstrated limited efficacy as single agent therapeutics. We generated a DARPin® therapeutic candidate, MP0310 (AMG 506), which comprises domains binding to 4-1BB and fibroblast activation protein (FAP). MP0310 triggers 4-1BB activation only if bound and clustered via FAP which is abundantly expressed by cancer associated fibroblasts present in many solid tumors. In vitro functional assays indicate that MP0310 is a potent T cell co-stimulator in the presence of FAP-expressing cells. In vivo activity of tumor-targeted 4-1BB agonism was assessed in the HT-29 colon carcinoma xenograft model in PBMC humanized mice in combination with a T cell engager. Consistent with tumor targeting, MP0310 enhanced intra-tumoral CD8 T cell expansion while showing only limited systemic activity. We used a translational pharmacokinetic-pharmacodynamic (PK-PD) modeling approach to integrate in vitro and in vivo data to support the estimation of a minimal anticipated biological effect level (MABEL) and the relevant dose range for first in human (FIH) studies. In addition to a PK model describing the MP0310 concentrations over time in mouse and monkey, direct and indirect response models were used to describe receptor occupancy (RO), intra-tumoral CD8 T cell infiltration and peripheral CD8 count kinetics. Predictions from the combined PK and PD models using average intra-tumoral and peripheral drug concentrations (Cav) provide a MABEL dose with minimal expected systemic PD effects at 20% RO as well as the anticipated therapeutic dose range in humans. In conclusion, our PK/PD-modeling approach provides support for the selection of a safe starting dose for MP0310 (AMG506) in patients. It provides a rationale for selecting the maximum tested dose, and may help reduce the number of cancer patients receiving sub-therapeutic doses. MP0310 (AMG 506) is currently being evaluated in a Ph1 clinical study. Citation Format: Alexander Link, Laurent Juglair, Heïdi Poulet, Guy Lemaillet, Christian Reichen, Patricia Schildknecht, Ivana Tosevski, Joanna Robinson, Niina Veitonmäki, Jörg Herbst, Keith Dawson, Christof Zitt, Camila de Almeida, Rik de Greef, Victor Levitsky, Michael T. Stumpp, Hong Ji, Elmar Vom Baur. Selection of first-in-human clinical dose range for the tumor-targeted 4-1BB agonist MP0310 (AMG 506) using a pharmacokinetic/pharmacodynamics modeling approach [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2273.

Superparamagnetic Iron Oxide Nanoparticles Carrying Chemotherapeutics Improve Drug Efficacy in Monolayer and Spheroid Cell Culture by Enabling Active Accumulation.

Cytotoxic and cytostatic chemotherapeutics act by attacking rapidly dividing tumor cells, predominantly affecting malignant tissue and to a certain degree preserving healthy cells. Nonetheless, severe side effects are caused as quickly proliferating healthy cells such as hematopoietic precursors and mucous membranes are impaired as well. This limits the administered dose and eventually allows tumor cells to escape treatment. In order to increase intratumoral drug concentration and simultaneously reduce systemic side effects, nanoparticles have come into focus as drug carriers. The functionalization of superparamagnetic iron oxide nanoparticles (SPIONs) with chemotherapeutics such as mitoxantrone (MTO) enables targeted drug transport by using magnetic forces. Here, we investigate SPIONs consisting of individual iron oxide cores of 10 nm in diameter and a total hydrodynamic diameter of 53 ± 0.8 nm as a transporting system for MTO. Comparing the killing efficacy in monolayer cell culture and multicellular tumor spheroids of HT-29 cells, we show that spheroids tolerate considerably higher doses of nanoparticle-loaded MTO. Therefore, dose predictions from conventional monolayer cell cultures are often misleading for in vivo applications. This was true for both soluble and nanoparticle-bound MTO. Using flow chambers mimicking in vivo blood flow, we furthermore demonstrate that SPIONs can magnetically accumulate MTO. We conclude that SPIONs can function as an effective delivery platform to increase local drug concentrations, thereby potentially overcoming chemotherapy resistance of cells.

Intra-tumoral drug concentration mapping within solid tumor micro-milieu using in-vitro model and doxorubicin as a model drug

In contrast to plasma pharmacokinetics, intratumoral pharmacokinetics of doxorubicin (DOX) determines its spatial anti-tumoral activity. Three-dimensional multicellular layers (MCL) model for solid tumors present optimum experimental platform for studying the intratumoral pharmacokinetics of DOX. This might imply new insights for understanding intratumoral pharmacokinetic parameters with realistic clinical implications. Herein, we are presenting simplified method for the spatial in-situ concentration assessment of DOX within the avascular simulating MCL solid tumor model of DLD-1 and HT-29 cell lines. DLD-1 and HT-29 formed viable well-structured MCL model abundant in extracellular matrix component (fibronectin). DOX (100 µM) showed stronger anti-proliferative effect against MCL of DLD-1 compared to HT-29 MCL (38.8% and 27.9%, respectively). The differential potencies of DOX closely correlate to the intratumoral pharmacokinetics within MCL’s of both cell lines. DOX penetrated faster and washed out slower through the MCL of DLD-1 compared to HT-29 MCL. Distribution of DOX within MCL of DLD-1 was more homogenous compared to HT-29 MCL. Tissue concentration of DOX within MCL of DLD-1 was significantly higher than HT-29 MCL’s after 96 h exposure (0.7 and 0.4 µmole/gm tissue, respectively). Concentration of DOX within MCL of both cell lines exceeded the IC50 under monolayer conditions (2.3 ± 0.6 µM and 0.6 ± 0.1 µM, respectively). In addition, DOX was extensively metabolized to less active metabolites (doxorubicinol and doxorubicinone) through the thickness of both MCL’s. In conclusion, Intratumoral pharmacokinetic barriers to DOX might be key determinant in drug resistance on the tissue level, despite cellular and molecular events.

Improving Treatment Efficacy of In Situ Forming Implants via Concurrent Delivery of Chemotherapeutic and Chemosensitizer

P-glycoprotein (Pgp), a member of the ATP-binding cassette family, is one of the major causes of multidrug resistance in tumors. Current clinical treatments to overcome MDR involve the co-delivery of a Pgp inhibitor and a chemotherapeutic. A concern for this treatment that has led to varied clinical trial success is the associated systemic toxicities involving endogenous Pgp. Local drug delivery systems, such as in situ forming implants (ISFIs), alleviate this problem by delivering a high concentration of the drug directly to the target site without the associated systemic toxicities. ISFIs are polymeric drug solutions that undergo a phase transition upon injection into an aqueous environment to form a solid drug eluting depot allowing for a high initial intratumoral drug concentration. In this study, we have developed an ISFI capable of overcoming the Pgp resistance by co-delivering a chemotherapeutic, Doxorubicin (Dox), with a Pgp inhibitor, either Pluronic P85 or Valspodar (Val). Studies investigated in vitro cytotoxicity of Dox when combined with either Pgp inhibitor, effect of the inhibitors on release of Dox from implants in PBS, in vivo Dox distribution and retention in a subcutaneous flank colorectal murine tumor, and therapeutic response characterized by tumor growth curves and histopathology. Dox + Val showed a 4-fold reduction in the 50% lethal dose (LD50) after 48 hours. Concurrent delivery of Dox and Val showed the greatest difference at 16 days post injection for both Dox penetration and retention. This treatment group had a 5-fold maximum Dox penetration compared to Dox alone ISFIs (0.53 ± 0.22 cm vs 0.11 ± 0.11 cm, respectively, from the center of the ISFI). Additionally, there was a 3-fold increase in normalized total intratumoral Dox intensity with the Dox + Val ISFIs compared to Dox alone ISFIs (0.54 ± 0.11 vs 0.18 ± 0.09, respectively). Dox + Val ISFIs showed a 2-fold reduction in tumor growth and a 27.69% increase in necrosis 20 days post-injection compared to Dox alone ISFIs. These findings demonstrate that co-delivery of Dox and Val via ISFI can avoid systemic toxicity issues seen with clinical Pgp inhibitors.

First-in-Humans Trial of Dasatinib-Derivative Tracer for Tumor Kinase-Targeted PET.

We developed a first-of-kind dasatinib-derivative imaging agent, 18F-SKI-249380 (18F-SKI), and validated its use for noninvasive in vivo tyrosine kinase-targeted tumor detection in preclinical models. In this study, we assessed the feasibility of using 18F-SKI for PET imaging in patients with malignancies. Methods: Five patients with a prior diagnosis of breast cancer, renal cell cancer, or leukemia underwent whole-body PET/CT imaging 90 min after injection of 18F-SKI (mean, 241.24 ± 116.36 MBq) as part of a prospective study. In addition, patients underwent either a 30-min dynamic scan of the upper abdomen including, at least partly, cardiac left ventricle, liver, spleen, and kidney (n = 2) or three 10-min whole-body PET/CT scans (n = 3) immediately after injection and blood-based radioactivity measurements to determine the time course of tracer distribution and facilitate radiation dose estimates. A subset of 3 patients had a delayed whole-body PET/CT scan at 180 min. Biodistribution, dosimetry, and tumor uptake were quantified. Absorbed doses were calculated using OLINDA/EXM 1.0. Results: No adverse events occurred after injection of 18F-SKI. In total, 27 tumor lesions were analyzed, with a median SUVpeak of 1.4 (range, 0.7-2.3) and tumor-to-blood ratios of 1.6 (range, 0.8-2.5) at 90 min after injection. The intratumoral drug concentrations calculated for 4 reference lesions ranged from 0.03 to 0.07 nM. In all reference lesions, constant tracer accumulation was observed between 30 and 90 min after injection. A blood radioassay indicated that radiotracer clearance from blood and plasma was initially rapid (blood half-time, 1.31 ± 0.81 min; plasma, 1.07 ± 0.66 min; n = 4), followed variably by either a prolonged terminal phase (blood half-time, 285 ± 148.49 min; plasma, 240 ± 84.85 min; n = 2) or a small rise to a plateau (n = 2). Like dasatinib, 18F-SKI underwent extensive metabolism after administration, as evidenced by metabolite analysis. Radioactivity was predominantly cleared via the hepatobiliary route. The highest absorbed dose estimates (mGy/MBq) in normal tissues were to the right colon (0.167 ± 0.04) and small intestine (0.153 ± 0.03). The effective dose was 0.0258 mSv/MBq (SD, 0.0034 mSv/MBq). Conclusion:18F-SKI demonstrated significant tumor uptake, distinct image contrast despite low injected doses, and rapid clearance from blood.

Convection-enhanced delivery of temozolomide and whole cell tumor immunizations in GL261 and KR158 experimental mouse gliomas

BackgroundGlioblastomas (GBM) are therapy-resistant tumors with a profoundly immunosuppressive tumor microenvironment. Chemotherapy has shown limited efficacy against GBM. Systemic delivery of chemotherapeutic drugs is hampered by the difficulty of achieving intratumoral levels as systemic toxicity is a dose-limiting factor. Although some of its effects might be mediated by immune reactivity, systemic chemotherapy can also inhibit induced or spontaneous antitumor immune reactivity. Convection-enhanced delivery of temozolomide (CED-TMZ) can tentatively increase intratumoral drug concentration while reducing systemic side effects. The objective of this study was to evaluate the therapeutic effect of intratumorally delivered temozolomide in combination with immunotherapy and whether such therapy can generate a cellular antitumor immune response.MethodsSingle bolus intratumoral injection and 3-day mini-osmotic pumps (Alzet®) were used to deliver intratumoral TMZ in C57BL6 mice bearing orthotopic gliomas. Immunotherapy consisted of subcutaneous injections of irradiated GL261 or KR158 glioma cells. Tumor size and intratumoral immune cell populations were analyzed by immunohistochemistry.ResultsCombined CED-TMZ and immunotherapy had a synergistic antitumor effect in the GL261 model, compared to CED-TMZ or immunotherapy as monotherapies. In the KR158 model, immunization cured a small proportion of the mice whereas addition of CED-TMZ did not have a synergistic effect. However, CED-TMZ as monotherapy prolonged the median survival. Moreover, TMZ bolus injection in the GL261 model induced neurotoxicity and lower cure rate than its equivalent dose delivered by CED. In addition, we found that T-cells were the predominant cells responsible for the TMZ antitumor effect in the GL261 model. Finally, CED-TMZ combined with immunotherapy significantly reduced tumor volume and increased the intratumoral influx of T-cells in both models.ConclusionsWe show that immunotherapy synergized with CED-TMZ in the GL261 model and cured animals in the KR158 model. Single bolus administration of TMZ was effective with a narrower therapeutic window than CED-TMZ. Combined CED-TMZ and immunotherapy led to an increase in the intratumoral influx of T-cells. These results form part of the basis for the translation of the therapy to patients with GBM but the dosing and timing of delivery will have to be explored in depth both experimentally and clinically.

Chemoembolization of liver cancer with doxorubicin-loaded CalliSpheres microspheres: plasma pharmacokinetics, intratumoral drug concentration, and tumor necrosis in a rabbit model.

The purpose of this work was to investigate the plasma pharmacokinetics, intratumoral drug concentration, and tumor necrosis after transarterial chemoembolization (TACE) with doxorubicin-loaded CalliSpheres microspheres (CSMs). Sixty rabbits with liver VX2 tumors were assigned into five groups of 12 rabbits each, which received 4mg of doxorubicin via intravenous injection (IV group), hepatic arterial infusion (IA group), conventional TACE (cTACE group), CSM-TACE (CSM low-dose group), and 8mg of doxorubicin via CSM-TACE (CSM high-dose group), respectively. Doxorubicin concentrations in plasma, tumor, and adjacent hepatic parenchyma were measured at various timepoints after treatment, and tumor necrosis percentage and liver enzymes were also assessed. The peak plasma concentration of doxorubicin was significantly lower in the three TACE groups compared to IV and IA group (P < 0.05), while doxorubicin concentrations in tumor and adjacent hepatic parenchyma were higher in the two CSM groups compared with IV, IA, and cTACE groups at 3days and 7days after treatment (P < 0.05). The percentages of tumor necrosis at 3 and 7days after treatment were significantly higher in three TACE groups (all higher than 50%) compared with IV group and IA group (both lower than 25%) (P < 0.05), and the highest tumor necrosis percentage was achieved in CSM high-dose group. The three TACE groups showed transient increases in transaminases levels after treatment, in which the peak transaminases levels were significantly lower in the two CSM groups than those in cTACE group (P < 0.05). CSM achieves an effective delivery of doxorubicin into liver cancer. High-dose doxorubicin improves tumoricidal capacity while not impairing the safety of the doxorubicin-loaded CSM.

Hepatic arterial infusion of irinotecan and EmboCept® S results in high tumor concentration of SN-38 in a rat model of colorectal liver metastases

Intraarterial chemotherapy for colorectal liver metastases (CRLM) can be applied alone or together with embolization particles. It remains unclear whether different types of embolization particles lead to higher intratumoral drug concentration. Herein, we quantified the concentrations of CPT-11 and its active metabolite SN-38 in plasma, liver and tumor tissue after hepatic arterial infusion (HAI) of irinotecan, with or without further application of embolization particles, in a rat model of CRLM. Animals underwent either systemic application of irinotecan, or HAI with or without the embolization particles Embocept® S and Tandem™. Four hours after treatment concentrations of CPT-11 and SN-38 were analyzed in plasma, tumor and liver samples by high-performance liquid chromatography. Additionally, DNA-damage and apoptosis were analyzed immunohistochemically. Tumor tissue concentrations of SN-38 were significantly increased after HAI with irinotecan and EmboCept® S compared to the other groups. The number of apoptotic cells was significantly higher after both HAI with irinotecan and EmboCept® S or Tandem™ loaded with irinotecan compared to the control group. HAI with irinotecan and EmboCept® S resulted in an increased SN-38 tumor concentration. Both HAI with irinotecan and EmboCept® S or Tandem™ loaded with irinotecan were highly effective with regard to apoptosis.

A Population Dynamic Energy Budget-Based Tumor Growth Inhibition Model for Etoposide Effects on Wistar Rats.

This work aimed to develop a population PK/PD tumor-in-host model able to describe etoposide effects on both tumor cells and host in Walker-256 tumor-bearing rats. Etoposide was investigated on thirty-eight Wistar rats randomized in five arms: two groups of tumor-free animals receiving either placebo or etoposide (10mg/kg bolus for 4days) and three groups of tumor-bearing animals receiving either placebo or etoposide (5 or 10mg/kg bolus for 8 or 4days, respectively). To analyze experimental data, a tumor-in-host growth inhibition (TGI) model, based on the Dynamic Energy Budget (DEB) theory, was developed. Total plasma and free-interstitial tumor etoposide concentrations were assessed as driver of tumor kinetics. The model simultaneously describes tumor and host growths, etoposide antitumor effect as well as cachexia phenomena related to both the tumor and the drug treatment. The schedule-dependent inhibitory effect of etoposide is also well captured when the intratumoral drug concentration is considered as the driver of the tumor kinetics. The DEB-based TGI model capabilities, up to now assessed only in mice, are fully confirmed in this study involving rats. Results suggest that well designed experiments combined with a mechanistic modeling approach could be extremely useful to understand drug effects and to describe all the dynamics characterizing in vivo tumor growth studies.

Development of a hybrid nanocarrier-recognizing tumor vasculature and penetrating the BBB for glioblastoma multi-targeting therapy.

The success of glioma chemotherapy is hampered by poor drug penetration ability across the blood-brain barrier (BBB) and low intratumoral drug concentration. Novel tumor-targeted delivery systems are useful in specifically accumulating in the tumor foci and penetrating into the glioma core after entering into the brain. Here we show that a multi-targeting hybrid nanocarrier (Pep-MLHA HNPs) system based on hyaluronic acid (HA)-modified polymer and a functional peptide possesses multi-target capability and stronger penetration ability into the core of three-dimensional tumor spheroids, could migrate efficiently across the BBB in vitro. The intensity of the Pep-MLHA HNPs after transporting across the BBB was 5.2-fold and 5.6-fold higher than that of ML NPs in C6 and U87 cells, respectively. More interestingly, this multi-targeting hybrid system displayed high colloidal stability in PBS solution, and weak negative zeta potential (-1.99 ± 0.655 mV) minimizing nonspecific interactions with plasma proteins and promoting long-term circulation in vivo. Additionally, the multi-targeting hybrid system induced enhanced tumor localization in U87 in situ-bearing nude mice and xenograft-bearing nude mice after systemic administration. Furthermore, docetaxel (DTX)-loaded Pep-MLHA HNPs showed negligible systemic toxicity and enhanced therapeutic efficacy, with significantly improved survival rates in intracranial C6 glioma-bearing rats. The 50% survival rate of DTX/Pep-MLHA HNPs-treated rats (40 days) was significantly longer than that of rats treated with NS (22 days), Taxotere® (25 days), DTX/ML NPs (25 days), DTX/Pep NPs (32 days) and DTX/MLHA NPs (29 days). All the results suggested that the multi-targeting hybrid nanocarrier system is promising for glioma treatment.

Cocktail Strategy Based on Spatio-Temporally Controlled Nano Device Improves Therapy of Breast Cancer.

Metastatic breast cancer may be resistant to chemo-immunotherapy due to the existence of cancer stem cells (CSC). Also, the control of particle size and drug release of a drug carrier for multidrug combination is a key issue influencing the therapy effect. Here, a cocktail strategy is reported, in which chemotherapy against both bulk tumor cells and CSC and immune checkpoint blockade therapy are intergraded into one drug delivery system. The chemotherapeutic agent paclitaxel (PTX), the anti-CSC agent thioridazine (THZ), and the PD-1/PD-L1 inhibitor HY19991 (HY) are all incorporated into an enzyme/pH dual-sensitive nanoparticle with a micelle-liposome double-layer structure. The particle size shrinks when the nanoparticle transfers from circulation to tumor tissues, favoring both pharmacokinetics and cellular uptake, meanwhile achieving sequential drug release where needed. This nano device, named PM@THL, increases the intratumoral drug concentrations in mice and exhibits significant anticancer efficacy, with tumor inhibiting rate of 93.45% and lung metastasis suppression rate of 97.64%. It also reduces the proportion of CSC and enhances the T cells infiltration in tumor tissues, and thus prolongs the survival of mice. The cocktail therapy based on the spatio-temporally controlled nano device will be a promising strategy for treating breast cancer.

MR imaging tracking of inflammation-activatable engineered neutrophils for targeted therapy of surgically treated glioma

Cell-based drug delivery systems have shown promising capability for tumor-targeted therapy owing to the intrinsic tumor-homing and drug-carrying property of some living cells. However, imaging tracking of their migration and bio-effects is urgently needed for clinical application, especially for glioma. Here, we report the inflammation-activatable engineered neutrophils by internalizing doxorubicin-loaded magnetic mesoporous silica nanoparticles (ND-MMSNs) which can provide the potential for magnetic resonance (MR) imaging tracking of the drug-loaded cells to actively target inflamed brain tumor after surgical resection of primary tumor. The phagocytized D-MMSNs possess high drug loading efficiency and do not affect the host neutrophils’ viability, thus remarkably improving intratumoral drug concentration and delaying relapse of surgically treated glioma. Our study offers a new strategy in targeted cancer theranostics through combining the merits of living cells and nanoparticle carriers.

Physiologically-based pharmacokinetic and pharmacodynamic models for gemcitabine and birinapant in pancreatic cancer xenografts.

The anticancer effects of combined gemcitabine and birinapant were demonstrated as synergistic in PANC-1 cells in vitro. In this study, pharmacokinetic information derived from experiments and the literature was utilized to develop full physiologically-based pharmacokinetic (PBPK) models that characterize individual drugs. The predicted intra-tumor drug concentrations were used as the driving force within a linked PBPK/PD model for treatment-mediated changes in tumor volume in a xenograft mouse model. The efficacy of the drug combination in vivo was evaluated mathematically as exhibiting additivity. The network model developed for drug effects in the in vitro cell cultures was applied successfully to link the in vivo tumor drug concentrations with tumor growth inhibition, incorporating more mechanistic features and accounting for disparate drug interaction outcomes in vitro and in vivo.

Abstract 4926: Preclinical intratumoral pharmacokinetics (PK) of capecitabine (Cap) given +/- eribulin (Eri)

Abstract Background: Eri &amp; Cap are active as single agents in metastatic breast cancer, but the combination appears particularly active &amp; well tolerated clinically. We explored the hypothesis that normalisation of tumor vasculature by Eri seen in preclinical models may enhance delivery of Cap to the tumor when given in combination. Methods: Mice bearing MDA-MD-231 xenografts were treated with Cap 540mg/kg p.o. day 1 alone or following Eri 1mg/kg i.v. on day -8 then sacrificed on day 1 at 15min, 30min, 1h, 2h, 4h, 6h or 24h after Cap (n=3/ time point). Concentrations of Cap &amp; its metabolites (5'-deoxy-5-fluorocytidine, 5DFCR; 5-Fluoro-5'-deoxyuridine, 5DFUR; 5-Fluorouracil, 5FU; 5-Fluorouridine, 5FUrd; &amp; 5-Fluoro-2'-deoxyuridine, 5FdUrd) in plasma, tumor, skin &amp; muscle were analysed by LC-MS/MS. Half the tumor was reserved to study Cap distribution using matrix-assisted laser desorption/ionization mass spectrometry imaging with haem imaged as a surrogate marker for tumour vasculature. Results: We found no differences in the plasma, skin, muscle or tumor PK profiles of Cape &amp; its metabolites with the addition of Eri (Table 1). In both treatment arms intratumoral concentrations of 5DFUR, 5FU, 5FUrd &amp; 5FdUrd appeared higher in tumors while those of Cape &amp; 5DFCR appeared higher in normal healthy tissues. To mitigate the variability in tumor Cape concentrations between animals, we also expressed the results as the ratio of drug concentration in tumour:healthy tissue but again found no apparent effect of Eri on intratumoral drug concentrations. Analyses of drug distribution are on-going &amp; will be presented. Conclusion: No clear effect of Eri on intratumoral concentrations of Cape or its metabolites was seen. We are exploring potential differences in tumour drug distribution. Citation Format: Maria Jove Casulleras, Jade Spencer, Paul Loadman, Malcolm Clench, Steve Shnyder, Patricia Cooper, Cristina Russo, Amanda Race, Ramon Salazar, Chris Twelves. Preclinical intratumoral pharmacokinetics (PK) of capecitabine (Cap) given +/- eribulin (Eri) [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 4926.

TEMPO-oxidized starch nanoassemblies of negligible toxicity compared with polyacrylic acids for high performance anti-cancer therapy

There is an urgent need for developing nanocarrier of excellent biocompatibility which can selectively release drugs at desired locations that can increase intratumoral drug concentration and reduce side effects. Herein, we developed a highly biocompatible nanocarrier made of oxidized starch in delivering doxorubicin (DOX) for enhanced anti-cancer therapy. The 30% oxidized starch can spontaneously self-assemble into 30–50 nm spherical nanoassemblies under physiological concentrations. DO30 nanoassemblies possessed negligible toxicity in several cell lines and ICR mice, in contrast to severe toxicity of synthetic polyacrylic acid (PAA), both of which are carboxyl-abundant polymers. The biocompatible DO30 was further decorated with cyclic RGD (Arg-Gly-Asp-Phe-Cys) peptides via PEG linker to target αvβ3 integrin overexpressed on HepG2 cells. RGD-PEG-DO30/DOX demonstrated an enhanced tumor-targeting ability and anti-cancer property in vitro and in vivo. In general, RGD-oxidized starch nanoassemblies showed a great potential as a new type of safe and effective nanocarrier for anti-cancer therapy.

Mibefradil dihydrochoride with hypofractionated radiation for recurrent glioblastoma: A phase I dose expansion trial.

e14046 Background: Recurrent Glioblastoma Multiforme (GBM) has limited treatment options. We performed a high-throughput screen for DNA repair inhibitors and identified mibefradil dihydrochloride, a T-type calcium channel blocker. We and others revealed that mibefradil acts as a glioma radiosensitizer. Recent studies in our laboratory indicate that mibefradil blocks non-homologous end joining. We sought to determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of mibefradil and radiation therapy (RT), in a Phase I recurrent GBM study. Methods: The Primary objective was to determine mibefradil MTD with concurrent hypofractionated RT. Secondary objectives included safety, pharmacokinetics, progression-free survival (PFS) and overall survival (OS). A tertiary objective included assessing intra-tumoral drug concentrations. In this novel translational sub-study, patients were given mibefradil for 5 days prior to surgery, followed by a re-resection. Resected tissues were analyzed for the presence of drug in situ. Inclusion criteria included histologically proven GBM progressive following RT and temozolomide. Patients received mibefradil, dose escalated from 150mg/day using a 3 + 3 design. RT consisted of 5 fractions of 600 cGy each, delivered over 2 weeks. Results: Nineteen patients enrolled from 9/2014 - 12/2016. There were 4 DLTs; a final dose level of 200 mg/day was reached. Median PFS and OS were 3 months and 9 months, respectively. Four patients (22%) achieved a PFS interval of ≥4 months (longest 8 months). One patient had a complete radiographic response. Intriguingly, mibefradil was detected at micromolar levels in GBM tumor tissue in 2 patients enrolled in the translational sub-study. We detected drug levels in biopsies from T1-post contrast and FLAIR regions on MRI and these levels correlate with that required for tumor cell radiosensitization in vitro. Conclusions: Our data suggest mibefradil can be safely co-administered with RT over a 17 day period at 200 mg/day. Promising local control signals apparent in a selection of patients, and we have demonstrated that pharmacologically effective concentrations of the drug are achieved in resected brain tumor tissue. Clinical trial information: NCT02202993.