Probing the Effects of the FGFR-Inhibitor Derazantinib on Vascular Development in Zebrafish Embryos.

Angiogenesis is a fundamental developmental process and a hallmark of cancer progression. Receptor tyrosine kinases (RTK) are targets for cancer therapy which may include their action as anti-angiogenic agents. Derazantinib (DZB) is an inhibitor of the fibroblast growth factor receptors (FGFRs) 1-3 as well as other kinase targets including vascular endothelial growth factor receptor 2 (VEGFR2), colony stimulating factor-1 receptor (CSF1R) and platelet-derived growth factor beta receptor (PDGFRbeta).

Continuous low-dose infusion of patupilone increases the therapeutic index in mouse and rat tumour models.

Patupilone is a microtubule-targeted cytotoxic agent with clinical efficacy, but causes diarrhoea in more than 80% of patients. The efficacy and tolerability of patupilone delivered continuously by subcutaneous (s.c.

Tumour T1 changes in vivo are highly predictive of response to chemotherapy and reflect the number of viable tumour cells--a preclinical MR study in mice.

Background: Effective chemotherapy rapidly reduces the spin-lattice relaxation of water protons (T1) in solid tumours and this change (ΔT1) often precedes and strongly correlates with the eventual change in tumour volume (TVol). To understand the biological nature of ΔT1, we have performed studies in vivo and ex vivo with the allosteric mTOR inhibitor, everolimus.

Methods: Mice bearing RIF-1 tumours were studied by magnetic resonance imaging (MRI) to determine TVol and T1, and MR spectroscopy (MRS) to determine levels of the proliferation marker choline and levels of lipid apoptosis markers, prior to and 5 days (endpoint) after daily treatment with vehicle or everolimus (10 mg/kg).

Patupilone (epothilone B) for recurrent glioblastoma: clinical outcome and translational analysis of a single-institution phase I/II trial.

Background: Patients with glioblastoma (GBM) inevitably develop recurrent or progressive disease after initial multimodal treatment and have a median survival of 6-9 months from time of progression. To date, there is no accepted standard treatment for GBM relapse or progression. Patupilone (EPO906) is a novel natural microtubule-stabilizing cytotoxic agent that crosses the blood-brain barrier and has been found to have preclinical activity in glioma models.

Microtubule stabilising agents and ionising radiation: multiple exploitable mechanisms for combined treatment.

Combined radiochemotherapy treatment modalities are in use for many indications and therefore of high interest. Even though a combined modality in clinical use is often driven by pragmatic aspects, mechanistic preclinical-based concepts of interaction are of importance in order to translate and implement an optimal combination and scheduling of two modalities into the clinics. The use of microtubule stabilising agents is a promising strategy for anti-cancer therapy as a part of combined treatment modality with ionising radiation.

Adaptation to HIF-1 deficiency by upregulation of the AMP/ATP ratio and phosphofructokinase activation in hepatomas.

Background: HIF-1 deficiency has marked effects on tumour glycolysis and growth. We therefore investigated the consequences of HIF-1 deficiency in mice, using the well established Hepa-1 wild-type (WT) and HIF-1β-deficient (c4) model. These mechanisms could be clinically relevant, since HIF-1 is now a therapeutic target.

Everolimus augments the effects of sorafenib in a syngeneic orthotopic model of hepatocellular carcinoma.

Sorafenib targets the Raf/mitogen-activated protein kinase, VEGF, and platelet-derived growth factor pathways and prolongs survival patients in advanced hepatocellular carcinoma (HCC). Everolimus inhibits the mammalian target of rapamycin, a kinase overactive in HCC. To investigate whether the antitumor effects of these agents are additive, we compared a combined and sequential treatment regimen of everolimus and sorafenib with monotherapy.

Regulation of VEGF-expression by patupilone and ionizing radiation in lung adenocarcinoma cells.

The use of microtubule stabilizing agents (MSAs) is a promising strategy for anti-cancer therapy alone and as part of combined treatment modalities with ionizing radiation. However MSA-provoked molecular and cellular processes including the regulation of intercellular, paracrine signaling pathways are far from clear. Here we investigated the interference of the novel, clinically relevant MSA patupilone (epothilone B) with the tumor-cell derived vascular endothelial growth factor (VEGF), which is most relevant for tumor angiogenesis.

Evaluation of the mTOR inhibitor, everolimus, in combination with cytotoxic antitumor agents using human tumor models in vitro and in vivo.

The aim was to determine the potential of the allosteric mammalian target of rapamycin inhibitor, everolimus, to act in combination with cytotoxic anticancer compounds in vitro and in vivo. A concomitant combination in vitro showed no evidence of antagonism, but enhanced the antiproliferative effects (additive to synergistic) with cisplatin, doxorubicin, 5-fluorouracil, gemcitabine, paclitaxel, and patupilone. Everolimus (1-5 mg/kg/d orally) was evaluated for antitumor activity in vivo alone or in combination with suboptimal cytotoxic doses using athymic nude mice bearing subcutaneous human H-596 lung, KB-31 cervical, or HCT-116 colon tumor xenografts.

Anti-Angiogenic/Vascular Effects of the mTOR Inhibitor Everolimus Are Not Detectable by FDG/FLT-PET.

Noninvasive functional imaging of tumors can provide valuable early-response biomarkers, in particular, for targeted chemotherapy. Using various experimental tumor models, we have investigated the ability of positron emission tomography (PET) measurements of 2-deoxy-2-[(18)F]fluoro-glucose (FDG) and 3'-deoxy-3'-[(18)F]fluorothymidine (FLT) to detect response to the allosteric mammalian target of rapamycin (mTOR) inhibitor everolimus. Tumor models were declared sensitive (murine melanoma B16/BL6 and human lung H596) or relatively insensitive (human colon HCT116 and cervical KB31), according to the IC(50) values (concentration inhibiting cell growth by 50%) for inhibition of proliferation in vitro (<10 nM and >1 microM, respectively).

Everolimus and PTK/ZK show synergistic growth inhibition in the orthotopic BL16/BL6 murine melanoma model.

Purpose: Everolimus (RAD001, Afinitor) is an mTORC1 pathway inhibitor, and vatalanib (PTK/ZK) is a pan VEGF-R tyrosine kinase inhibitor (TKI). These two drugs have been shown to have overlapping but also distinct anti-angiogenic effects. Consequently, we investigated the pharmacokinetics (PK) and pharmacodynamics (PD) of their combination in vivo.

Biomarker Development for the Clinical Activity of the mTOR Inhibitor Everolimus (RAD001): Processes, Limitations, and Further Proposals.

The mTOR inhibitor everolimus (RAD001, Afinitor) is an orally active anticancer agent. Everolimus demonstrates growth-inhibitory activity against a broad range of tumor cell histotypes in vitro and has the capacity to retard tumor growth in preclinical tumor models in vivo through mechanisms directed against both the tumor cell and the solid tumor stroma components. These properties have rendered it to be a clinically active drug, with subsequent registration in renal cell carcinoma (Motzer et al.

Quantified tumor t1 is a generic early-response imaging biomarker for chemotherapy reflecting cell viability.

Purpose: Identification of a generic response biomarker by comparison of chemotherapeutics with different action mechanisms on several noninvasive biomarkers in experimental tumor models.

Experimental Design: The spin-lattice relaxation time of water protons (T(1)) was quantified using an inversion recovery-TrueFISP magnetic resonance imaging method in eight different experimental tumor models before and after treatment at several different time points with five different chemotherapeutics. Effects on T(1) were compared with other minimally invasive biomarkers including vascular parameters, apparent diffusion coefficient, and interstitial fluid pressure, and were correlated with efficacy at the endpoint and histologic parameters.

Comparative pharmacokinetics of RAD001 (everolimus) in normal and tumor-bearing rodents.

Purpose: Comparative pharmacokinetic (PK) analysis of the mTOR inhibitor RAD001 (everolimus) in rats and mice.

Methods: Blood cell partitioning, plasma protein binding and PK parameters of RAD001 in blood and tissues (including brain) of both mice and rats were determined. PK modeling predicted plasma/blood and tumor levels from a variety of regimens and these were compared with the known human PK profile.

Tumor interstitial fluid pressure as an early-response marker for anticancer therapeutics.

Solid tumors have a raised interstitial fluid pressure (IFP) due to high vessel permeability, low lymphatic drainage, poor perfusion, and high cell density around the blood vessels. To investigate tumor IFP as an early-response biomarker, we have tested the effect of seven anticancer chemotherapeutics including cytotoxics and targeted cytostatics in 13 experimental tumor models. IFP was recorded with the wick-in-needle method.

Role of the microenvironment for radiosensitization by patupilone.

Purpose: The combined treatment modality of ionizing radiation (IR) and the clinically relevant microtubule-stabilizing compound patupilone (epothilone B, EPO906) is a promising approach for anticancer therapy. Here, we investigated the role of the tumor microenvironment for the supra-additive in vivo response in tumor xenografts derived from patupilone-sensitive and patupilone-resistant non-small cell lung cancer cells.

Experimental Design: The treatment response to a combined regimen of patupilone and IR was investigated in vitro and in tumor xenografts derived from wild-type A549 and A549.

mTOR inhibitor RAD001 (everolimus) has antiangiogenic/vascular properties distinct from a VEGFR tyrosine kinase inhibitor.

Purpose: Comparison of the antiangiogenic/vascular properties of the oral mammalian target of rapamycin (mTOR) inhibitor RAD001 (everolimus) and the vascular endothelial growth factor receptor (VEGFR) inhibitor vatalanib (PTK/ZK).

Experimental Design: Antiproliferative activity against various tumor histotypes and downstream effects on the mTOR pathway were measured in vitro. In vivo, antitumor activity, plasma, and tumor RAD001 levels were measured.

Effects of the dual phosphatidylinositol 3-kinase/mammalian target of rapamycin inhibitor NVP-BEZ235 on the tumor vasculature: implications for clinical imaging.

Dysregulated angiogenesis and high tumor vasculature permeability, two vascular endothelial growth factor (VEGF)-mediated processes and hallmarks of human tumors, are in part phosphatidylinositol 3-kinase (PI3K) dependent. NVP-BEZ235, a dual PI3K/mammalian target of rapamycin (mTOR) inhibitor, was found to potently inhibit VEGF-induced cell proliferation and survival in vitro and VEGF-induced angiogenesis in vivo as shown with s.c.

Pharmacokinetic profile of the microtubule stabilizer patupilone in tumor-bearing rodents and comparison of anti-cancer activity with other MTS in vitro and in vivo.

Introduction: Patupilone is a microtubule stabilizer (MTS) currently in clinical development. Here, we evaluate the anti-cancer activity in vitro and in vivo in comparison to paclitaxel and describe the pharmacokinetics (PK) of patupilone in tumor-bearing nude mice and rats.

Methods: The potency in vitro of patupilone and two other MTS, paclitaxel and ixabepilone, was determined using human colon carcinoma cell lines with low (HCT-116, HT-29, RKO) and high (HCT-15) P-glycoprotein expression (P-gp), as well as two multi-drug resistance (MDR) model cell pairs, MCF7/ADR and KB-8511 cells and their respective drug-sensitive parental counterparts.

Quantitative dynamic contrast-enhanced MRI in tumor-bearing rats and mice with inversion recovery TrueFISP and two contrast agents at 4.7 T.

Purpose: To characterize tumor vascularization by dynamic-contrast enhanced (DCE) MRI using low and medium molecular weight paramagnetic contrast agents (CA) and inversion recovery (IR) true fast imaging with steady state precession (TrueFISP) in tumor-bearing rats and mice.

Materials And Methods: T(1) mapping was performed using IR True FISP in phantoms and in vivo at 4.7 T and validated with a segmented IR gradient-echo (IR GE) method.

Minimally invasive pharmacokinetic and pharmacodynamic technologies in hypothesis-testing clinical trials of innovative therapies.

Clinical trials of new cancer drugs should ideally include measurements of parameters such as molecular target expression, pharmacokinetic (PK) behavior, and pharmacodynamic (PD) endpoints that can be linked to measures of clinical effect. Appropriate PK/PD biomarkers facilitate proof-of-concept demonstrations for target modulation; enhance the rational selection of an optimal drug dose and schedule; aid decision-making, such as whether to continue or close a drug development project; and may explain or predict clinical outcomes. In addition, measurement of PK/PD biomarkers can minimize uncertainty associated with predicting drug safety and efficacy, reduce the high levels of drug attrition during development, accelerate drug approval, and decrease the overall costs of drug development.

Patupilone induced vascular disruption in orthotopic rodent tumor models detected by magnetic resonance imaging and interstitial fluid pressure.

Purpose: Evaluation of vascular disruptive activity in orthotopic models as potential surrogate biomarkers of tumor response to the microtubule-stabilizing agent patupilone.

Experimental Design: Mice bearing metastatic B16/BL6 melanoma and rats bearing mammary BN472 tumors received vehicle or efficacious patupilone doses (4 and 0.8-1.

Biomarkers for assessment of pharmacologic activity for a vascular endothelial growth factor (VEGF) receptor inhibitor, PTK787/ZK 222584 (PTK/ZK): translation of biological activity in a mouse melanoma metastasis model to phase I studies in patients with advanced colorectal cancer with liver metastases.

PTK/ZK is a novel, oral angiogenesis inhibitor that specifically targets all 3 vascular endothelial growth factor (VEGF) receptor tyrosine kinases and is currently in phase III clinical trials. In early clinical trials, PTK/ZK demonstrated a dose-dependent reduction in tumor vascular parameters as measured by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and an acute increase in plasma VEGF levels. The reduction in tumor vascularity was significantly correlated with improved clinical outcome in patients with advanced colorectal cancer and liver metastases.

Patupilone (epothilone B, EPO906) inhibits growth and metastasis of experimental prostate tumors in vivo.

Background: Microtubule agents appear promising for the treatment of prostate cancer. Patupilone (epothilone B), a highly potent non-taxane microtubule stabilizing agent, was evaluated in models of androgen-independent prostate cancer.

Methods: Patupilone was administered to athymic mice bearing human prostate cancer xenografts (subcutaneous DU 145 and PC-3M, orthotopic PC-3M).

PTK787/ZK222584, a tyrosine kinase inhibitor of vascular endothelial growth factor receptor, reduces uptake of the contrast agent GdDOTA by murine orthotopic B16/BL6 melanoma tumours and inhibits their growth in vivo.

Assessment of tumour vascularity may characterize malignancy as well as predict responsiveness to anti-angiogenic therapy. Non-invasive measurement of tumour perfusion and blood vessel permeability assessed as the transfer constant, K(trans), can be provided by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Using the orthotopic murine tumour model B16/BL6 melanoma, the small contrast agent GdDOTA (DOTAREM(R); Guerbet, Paris) was applied to assess the vascular transfer constant, K(trans), and interstitial leakage space, whereas intravascular iron oxide nanoparticles (Endorem(R); Guerbet, Paris) were used to detect relative tumour blood volume (rTBV), and in one experiment blood flow index (BFI).