Longitudinal PET Imaging to Monitor Treatment Efficacy by Liposomal Irinotecan in Orthotopic Patient-Derived Pancreatic Tumor Models of High and Low Hypoxia

Purpose

Hypoxia is linked to aggressiveness, resistance to therapy, and poor prognosis of pancreatic tumors. Liposomal irinotecan (nal-IRI, ONIVYDE®) has shown potential in reducing hypoxia in the HT29 colorectal cancer model, and here, we investigate its therapeutic activity and ability to modulate hypoxia in patient-derived orthotopic tumor models of pancreatic cancer.

Procedures

Mice were randomized into nal-IRI treated and untreated controls. Magnetic resonance imaging was used for monitoring treatment efficacy, positron emission tomography (PET) imaging with F-18-labelled fluoroazomycinarabinoside ([¹⁸F]FAZA) for tumor hypoxia quantification, and F-18-labelled fluorothymidine ([¹⁸F]FLT) for tumor cell proliferation.

Results

The highly hypoxic OCIP51 tumors showed significant response following nal-IRI treatment compared with the less hypoxic OCIP19 tumors. [¹⁸F]FAZA-PET detected significant hypoxia reduction in treated OCIP51 tumors, 8 days before significant changes in tumor volume. OCIP19 tumors also responded to therapy, although tumor volume control was not accompanied by any reduction in [¹⁸F]FAZA uptake. In both models, no differences were observable in [¹⁸F]FLT uptake in treated tumors compared with control mice.

Conclusions

Hypoxia modulation may play a role in nal-IRI’s mechanism of action. Nal-IRI demonstrated greater anti-tumor activity in the more aggressive and hypoxic tumor model. Furthermore, hypoxia imaging provided early prediction of treatment response.

Electronic supplementary material

The online version of this article (10.1007/s11307-019-01374-x) contains supplementary material, which is available to authorized users.

Deposition characteristics and resulting DNA damage patterns of liposomal irinotecan (nal-IRI) in pancreatic cancer xenografts

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Background: Liposomal irinotecan (nal-IRI, ONIVYDE) is approved in the US, EU and other countries in combination with 5-fluorouracil/leucovorin for treatment of patients with metastatic pancreatic cancer after disease progression following gemcitabine-based therapy. We report pharmacokinetic and extended pharmacodynamic effects of nal-IRI in pancreatic tumor models compared to non-liposomal irinotecan HCl. Methods: AsPC-1, BxPC-3 and CFPAC-1 tumors were grown in NOD-SCID mice. For efficacy animals were dosed q7d with 25-50 mg/kg irinotecan HCl or at 5x lower doses of nal-IRI. For PK-PD studies doses of 10-50 mg/kg of fluorescently-labeled nal-IRI were used; samples were collected up to 72 hr for irinotecan HCl and up to 168 hr for nal-IRI. Tumor samples were evaluated for liposome localization, macrophage and tumor markers, vessels, DNA damage and apoptosis. Results: nal-IRI yields sustained circulation and delivery of its payload to tumors compared to irinotecan HCl. This results in improved control of growth rates across a range of pancreatic tumor models even at 5x lower doses. DNA damage in BxPC-3 tumors has a comparable extent with both formulations, but is maximal at 6 hr after irinotecan HCl (50 mg/kg) and at 72 hr after nal-IRI (10 mg/kg). Liposomes deposit in tumors heterogeneously around functional vessels. Accumulation peaks at 6 - 24 hr with similar deposition patterns in cell- or patient-derived xenografts. Liposomes are predominantly taken up by macrophages and to a lesser extent by tumor or other stromal cells. DNA damage is mostly confined to tumor cells, a majority of which have not internalized liposomes. DNA damage and apoptosis are seen only minimally in non-tumor cells even when displaying high liposome uptake. Conclusions: nal-IRI improves tumoral deposition of its payload in pancreatic tumor models. Deposition is heterogeneous and restricted to perivascular areas. DNA damage predominantly in tumor cells outside of the liposomal deposition area suggests sufficient intratumoral levels of the SN-38 active metabolite, possibly after payload release by stromal macrophages and concomitant conversion. Effects of repeated dosing cycles should be explored.

Abstract CT146: Plasma pharmacokinetics of liposomal irinotecan (nal-IRI) in pediatric oncology patients with recurrent or refractory solid tumors: South Plains Oncology Consortium Study 2012-001

Background/Objectives: Children with relapsed or refractory solid tumors have a poor prognosis. Irinotecan is active in some pediatric solid tumors and synergizes with alkylating agents. nal-IRI encapsulates irinotecan into long-circulating, liposome-based nanoparticles. In adults, nal-IRI demonstrated extended plasma exposure compared with non-liposomal irinotecan. In pediatric solid tumor models, nal-IRI had robust preclinical activity and synergized with cyclophosphamide, and therefore merits testing in children with relapsed and refractory solid tumors. Herein we describe a phase 1 dose-escalation study of nal-IRI in combination with cyclophosphamide (NCT02013336) and preliminary pharmacokinetic and safety results.

Methods: Cyclophosphamide was administered on days 1-5 of each cycle (250 mg/m2/d intravenously [IV]) with a single 90-min IV infusion of nal-IRI on day 3 of a Q3-week schedule, escalating from 60 mg/m2 to 210 mg/m2 (expressed as irinotecan HCL trihydrate salt), in a standard 3+3 dose-escalation design to determine the maximum tolerated dose. To date, the nal-IRI dose has been escalated from 60 mg/m2 to 150 mg/m2. Samples for pharmacokinetic analysis were collected during the first cycle of chemotherapy before infusion and at 4h, 24h, 48h, 120h, and 168h post-infusion. Plasma pharmacokinetics of total irinotecan and SN-38 were quantified using mixed effect modeling, and were compared with adult values from a population pharmacokinetic analysis of 6 clinical studies of nal-IRI.1

Results: To date, 10 males and 6 females with a median age of 12.8 years (range: 5-19) have been enrolled: 10 with Ewing sarcoma, 2 with neuroblastoma, 3 with osteosarcoma, and 1 with rhabdomyosarcoma. The estimated total irinotecan volume of distribution (Vd) was 1.9 L, clearance (CL) was 10.3 L/week, and half-life (t1/2) was 21.2 h, which were 42% (Vd and CL) of adult values and comparable to adult values (t1/2). The corresponding Cmax was 72% higher than that observed in adults. SN-38 clearance was 11.4 L/week (comparable to adults), t1/2 was 19.3 h (48% of adult values), and Cmax was 68% of adult values. Thrombocytopenia leading to treatment delay was a dose-limiting toxicity at 150 mg/m2 (n=1); other systemic toxicity attributed to chemotherapy within the 1st cycle was nausea/vomiting (n=1).

Conclusions: Preliminary safety and pharmacokinetic data support continued investigation of nal-IRI in pediatric oncology. Clinical outcomes including safety of patients treated in this study will be reported once a maximum tolerated dose is achieved.

1. Adiwijaya B et al. Clin Pharmacol Ther. 2017. In press.

Citation Format: Paul D. Harker-Murray, William H. Meyer, Patrick Leavey, Min H. Kang, Hwangeui Cho, Bambang S. Adiwijaya, Jonathan B. Fitzgerald, J Marc Pipas, Daryl C. Drummond, C. Patrick Reynolds. Plasma pharmacokinetics of liposomal irinotecan (nal-IRI) in pediatric oncology patients with recurrent or refractory solid tumors: South Plains Oncology Consortium Study 2012-001 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT146. doi:10.1158/1538-7445.AM2017-CT146

Correlation between Ferumoxytol Uptake in Tumor Lesions by MRI and Response to Nanoliposomal Irinotecan in Patients with Advanced Solid Tumors: A Pilot Study

Purpose: To determine whether deposition characteristics of ferumoxytol (FMX) iron nanoparticles in tumors, identified by quantitative MRI, may predict tumor lesion response to nanoliposomal irinotecan (nal-IRI).Experimental Design: Eligible patients with previously treated solid tumors had FMX-MRI scans before and following (1, 24, and 72 hours) FMX injection. After MRI acquisition, R2* signal was used to calculate FMX levels in plasma, reference tissue, and tumor lesions by comparison with a phantom-based standard curve. Patients then received nal-IRI (70 mg/m² free base strength) biweekly until progression. Two percutaneous core biopsies were collected from selected tumor lesions 72 hours after FMX or nal-IRI.Results: Iron particle levels were quantified by FMX-MRI in plasma, reference tissues, and tumor lesions in 13 of 15 eligible patients. On the basis of a mechanistic pharmacokinetic model, tissue permeability to FMX correlated with early FMX-MRI signals at 1 and 24 hours, while FMX tissue binding contributed at 72 hours. Higher FMX levels (ranked relative to median value of multiple evaluable lesions from 9 patients) were significantly associated with reduction in lesion size by RECIST v1.1 at early time points (P < 0.001 at 1 hour and P < 0.003 at 24 hours FMX-MRI, one-way ANOVA). No association was observed with post-FMX levels at 72 hours. Irinotecan drug levels in lesions correlated with patient's time on treatment (Spearman ρ = 0.7824; P = 0.0016).Conclusions: Correlation between FMX levels in tumor lesions and nal-IRI activity suggests that lesion permeability to FMX and subsequent tumor uptake may be a useful noninvasive and predictive biomarker for nal-IRI response in patients with solid tumors. Clin Cancer Res; 23(14); 3638-48. ©2017 AACR.

Preclinical antitumor activity of nanoliposomal irinotecan (Nal-IRI, MM-398) and utilization as a foundation of front-line pancreatic cancer regimens

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Background: Nanoliposomal irinotecan (nal-IRI, MM-398) recently gained approval in combination with 5-fluorouracil/leucovorin (5-FU/LV) in post-gemcitabine metastatic pancreatic ductal adenocarcinoma (PDAC) based on the extended survival and manageable safety profile observed in the Phase 3 NAPOLI-1 trial. Preclinically, we have previously demonstrated the anti-tumor activity of nal-IRI with 5-FU and oxaliplatin, standard of care agents in first-line PDAC, and are currently investigating this combination in patients with previously untreated metastatic PDAC in a Phase 2 clinical trial (NCT02551991). Herein, we further evaluate nal-IRI as a potential backbone of first-line metastatic PDAC by assessing the preclinical anti-tumor activity of nal-IRI relative to, and in combination with, gemcitabine and nanoparticle albumin-bound-paclitaxel (nab-P). Methods: Nal-IRI tumor metabolite (CPT-11 and SN-38) levels were measured in mice treated with nal-IRI in combination with gemcitabine or nab-P. Anti-tumor activity and tolerability of nal-IRI, 5-FU, gemcitabine and nab-P monotherapies and combinations were evaluated using pancreatic cancer cell line (ASPC-1 and CFPAC-1)-derived xenograft models, as well as a panel of five patient-derived xenograft models. Results: Administration of gemcitabine or nab-P prior to or simultaneously with nal-IRI resulted in unchanged or increased nal-IRI deposition, as measured by tumor CPT-11 and SN-38 levels at 24 hours post-injection. Moreover, in both cell line-derived and patient-derived xenograft models of PDAC, nal-IRI monotherapy demonstrated comparable or improved anti-tumor activity relative to gemcitabine or nab-P monotherapies. Further, nal-IRI consistently improved tumor growth inhibition and survival when used in combination with either 5-FU, gemcitabine and/or nab-P, relative to the combination of gemcitabine plus nab-P. All treatments were well-tolerated in these preclinical models. Conclusions: These findings illustrate the compatibility and therapeutic potential of nal-IRI as a foundation of first-line PDAC combination regimens, and warrant clinical evaluation.

Abstract 4830: Preclinical anti-tumor activity of nanoliposomal irinotecan (Nal-IRI, MM-398) + 5-FU + oxaliplatin in pancreatic cancer

Nanoliposomal irinotecan (Nal-IRI, MM-398) recently gained approval in combination with 5-fluorouracil/leucovorin (5-FU/LV) in post-gemcitabine metastatic pancreatic cancer based on results of the Phase 3 NAPOLI-1 trial. Nal-IRI, in combination with 5-FU/LV, improved overall survival in gemcitabine-refractory metastatic PDAC relative to 5-FU/LV alone with a well-defined and manageable toxicity profile in pretreated patients. FOLFIRINOX (5-FU/LV, irinotecan and oxaliplatin) is a chemotherapy regimen active in first-line metastatic PDAC. Herein, we evaluate the preclinical anti-tumor activity of a nal-IRI + 5-FU + oxaliplatin regimen relative to the FOLFIRINOX regimen. Using pancreatic cancer cell lines, we demonstrate enhanced cell death when nal-IRI treatment is simulated using prolonged exposure of SN-38 (the active metabolite of irinotecan) in combination with 5-FU and oxaliplatin. In cell line-derived and patient-derived xenograft models of pancreatic cancer we demonstrate improved anti-tumor activity of nal-IRI relative to exposure-matched doses of unencapsulated irinotecan. Further, nal-IRI consistently improved tumor growth inhibition and survival relative to unencapsulated irinotecan in preclinical models, both as a monotherapy and in combination with 5-FU and oxaliplatin. The addition of nal-IRI to 5-FU and/or oxaliplatin did not exacerbate the baseline toxicities of these agents, including weight loss and neutropenia, and tolerability could be further improved by delaying the administration of oxaliplatin to 1 day post-MM-398. These findings illustrate the therapeutic potential of nal-IRI in combination with 5-FU/LV and oxaliplatin and support an ongoing Phase 2 trial (NCT02551991) of this triplet regimen in first-line PDAC.

Citation Format: Daniel F. Gaddy, Helen Lee, Nancy Paz, Shannon C. Leonard, Ashish Kalra, Ninfa L. Straubinger, Robert M. Straubinger, Bryan M. Gillard, Michael T. Moser, Daryl C. Drummond, Stephan G. Klinz, Bart S. Hendriks, Jonathan B. Fitzgerald. Preclinical anti-tumor activity of nanoliposomal irinotecan (Nal-IRI, MM-398) + 5-FU + oxaliplatin in pancreatic cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4830.

Activity of MM-398, nanoliposomal irinotecan (nal-IRI), in Ewing's family tumor xenografts is associated with high exposure of tumor to drug and high SLFN11 expression

PURPOSE

To determine the pharmacokinetics and the antitumor activity in pediatric cancer models of MM-398, a nanoliposomal irinotecan (nal-IRI).

EXPERIMENTAL DESIGN

Mouse plasma and tissue pharmacokinetics of nal-IRI and the current clinical formulation of irinotecan were characterized. In vivo activity of irinotecan and nal-IRI was compared in xenograft models (3 each in nu/nu mice) of Ewing's sarcoma family of tumors (EFT), neuroblastoma (NB), and rhabdomyosarcoma (RMS). SLFN11 expression was assessed by Affymetrix HuEx arrays, Taqman RT-PCR, and immunoblotting.

RESULTS

Plasma and tumor concentrations of irinotecan and SN-38 (active metabolite) were approximately 10-fold higher for nal-IRI than for irinotecan. Two doses of NAL-IRI (10 mg/kg/dose) achieved complete responses maintained for >100 days in 24 of 27 EFT-xenografted mice. Event-free survival for mice with RMS and NB was significantly shorter than for EFT. High SLFN11 expression has been reported to correlate with sensitivity to DNA damaging agents; median SLFN11 mRNA expression was >100-fold greater in both EFT cell lines and primary tumors compared with NB or RMS cell lines or primary tumors. Cytotoxicity of SN-38 inversely correlated with SLFN11 mRNA expression in 20 EFT cell lines.

CONCLUSIONS

In pediatric solid tumor xenografts, nal-IRI demonstrated higher systemic and tumor exposures to SN-38 and improved antitumor activity compared with the current clinical formulation of irinotecan. Clinical studies of nal-IRI in pediatric solid tumors (especially EFT) and correlative studies to determine if SLFN11 expression can serve as a biomarker to predict nal-IRI clinical activity are warranted.

Abstract OT3-02-14: A phase 1 study in patients with metastatic breast cancer to evaluate the feasibility of magnetic resonance imaging with ferrumoxytol as a potential biomarker for response to treatment with nanoliposomal irinotecan (nal-IRI, MM-398)

Background: Nal-IRI (MM-398, nanoliposomal irinotecan) is designed for extended circulation relative to free irinotecan and to exploit leaky tumor vasculature for enhanced drug delivery to tumors. Tumor deposition of nal-IRI and subsequent conversion to SN-38 in both neoplastic cells and tumor associated macrophages (TAM) may positively correlate with response to therapy. In phase I studies of nal-IRI, activity has been shown in metastatic breast cancer (MBC), pancreatic and colorectal cancer. Ferumoxytol (FMX) is an iron-oxide superparamagnetic nanoparticle that has been used off-label for its MRI contrast properties. FMX has long-circulating pharmacokinetics and is taken up by TAMs with similar distribution patterns to nal-IRI in preclinical models. A single site pilot study established the feasibility of performing quantitative FMX MRI. Thirteen patients with advanced cancer (3 with ER/PR+ MBC) were imaged with FMX MRI and treated with nal-IRI. Median tumor lesion FMX uptake in the pilot study was 32.6 and 34.5 μg/mL at 1 h and 24 h, respectively. Lesions with FMX uptake above the median were associated with greater reductions in tumor size following treatment with nal-IRI as determined by CT lesion measurements. The relationship between FMX levels in tumor lesions and nal-IRI activity may serve as a potential biomarker for nal-IRI deposition and response in solid tumors. This study has been expanded to include additional MBC patients to further evaluate the technical feasibility of FMX MRI at multiple study sites, and to evaluate activity of nal-IRI in patients with MBC.

Trial Design: Three cohorts of 10 patients with MBC in the following categories will be enrolled: ER and/or PR positive/HER2-negative, triple negative (TNBC) and MBC with brain metastases. An imaging phase will be followed by a treatment phase. The imaging phase consists of a baseline MRI scan, FMX infusion, and follow-up MRI scans at 1-4 and 24 h after infusion. The treatment phase begins 1-6 days after imaging and consists of nal-IRI 80 mg/m2 q2w. A pretreatment biopsy is required for correlative studies.

Study Objectives: The primary objective of this multisite expansion is to investigate the feasibility of FMX quantitation in tumor lesions at multiple lesion sites in breast cancer. The secondary objective is to characterize the efficacy of nal-IRI in patients with metastatic breast cancer.

Eligibility Criteria: The key inclusion criteria include patients with MBC, ECOG 0 or 1 with adequate bone marrow reserve and no prior topoisomerase 1 inhibitor or anti-VEGF treatment. ER and/or PR positive/HER2-negative and TNBC patients must have had 1-3 prior lines of chemotherapy in the metastatic setting and have at least 2 measurable lesions. Patients with brain metastasis must be neurologically stable and have new or progressive brain metastases after prior radiation therapy with at least one lesion measuring ≥ 1 cm in longest diameter on gadolinium-enhanced MRI.

Status: This trial is currently recruiting patients.

Citation Format: Sachdev JC, Ramanathan RK, Raghunand N, Anders C, Munster P, Minton S, Northfelt D, Blanchette S, Campbell K, Lee H, Klinz SG, Hendriks BS, Moyo V, Fitzgerald JB, Korn RL. A phase 1 study in patients with metastatic breast cancer to evaluate the feasibility of magnetic resonance imaging with ferrumoxytol as a potential biomarker for response to treatment with nanoliposomal irinotecan (nal-IRI, MM-398). [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 OT3-02-14.

Enhanced Targeting of the EGFR Network with MM-151, an Oligoclonal Anti-EGFR Antibody Therapeutic

Although EGFR is a validated therapeutic target across multiple cancer indications, the often modest clinical responses to current anti-EGFR agents suggest the need for improved therapeutics. Here, we demonstrate that signal amplification driven by high-affinity EGFR ligands limits the capacity of monoclonal anti-EGFR antibodies to block pathway signaling and cell proliferation and that these ligands are commonly coexpressed with low-affinity EGFR ligands in epithelial tumors. To develop an improved antibody therapeutic capable of overcoming high-affinity ligand-mediated signal amplification, we used a network biology approach comprised of signaling studies and computational modeling of receptor-antagonist interactions. Model simulations suggested that an oligoclonal antibody combination may overcome signal amplification within the EGFR:ERK pathway driven by all EGFR ligands. Based on this, we designed MM-151, a combination of three fully human IgG1 monoclonal antibodies that can simultaneously engage distinct, nonoverlapping epitopes on EGFR with subnanomolar affinities. In signaling studies, MM-151 antagonized high-affinity EGFR ligands more effectively than cetuximab, leading to an approximately 65-fold greater decrease in signal amplification to ERK. In cell viability studies, MM-151 demonstrated antiproliferative activity against high-affinity EGFR ligands, either singly or in combination, while cetuximab activity was largely abrogated under these conditions. We confirmed this finding both in vitro and in vivo in a cell line model of autocrine high-affinity ligand expression. Together, these preclinical studies provide rationale for the clinical study of MM-151 and suggest that high-affinity EGFR ligand expression may be a predictive response marker that distinguishes MM-151 from other anti-EGFR therapeutics.

Preclinical activity of nanoliposomal irinotecan is governed by tumor deposition and intratumor prodrug conversion

A major challenge in the clinical use of cytotoxic chemotherapeutics is maximizing efficacy in tumors while sparing normal tissue. Irinotecan is used for colorectal cancer treatment but the extent of its use is limited by toxic side effects. Liposomal delivery systems offer tools to modify pharmacokinetic and safety profiles of cytotoxic drugs. In this study, we defined parameters that maximize the antitumor activity of a nanoliposomal formulation of irinotecan (nal-IRI). In a mouse xenograft model of human colon carcinoma, nal-IRI dosing could achieve higher intratumoral levels of the prodrug irinotecan and its active metabolite SN-38 compared with free irinotecan. For example, nal-IRI administered at doses 5-fold lower than free irinotecan achieved similar intratumoral exposure of SN-38 but with superior antitumor activity. Tumor response and pharmacokinetic modeling identified the duration for which concentrations of SN-38 persisted above a critical intratumoral threshold of 120 nmol/L as determinant for antitumor activity. We identified tumor permeability and carboxylesterase activity needed for prodrug activation as critical factors in achieving longer duration of SN-38 in tumors. Simulations varying tumor permeability and carboxylesterase activity predicted a concave increase in tumor SN-38 duration, which was confirmed experimentally in 13 tumor xenograft models. Tumors in which higher SN-38 duration was achieved displayed more robust growth inhibition compared with tumors with lower SN-38 duration, confirming the importance of this factor in drug response. Overall, our work shows how liposomal encapsulation of irinotecan can safely improve its antitumor activity in preclinical models by enhancing accumulation of its active metabolite within the tumor microenvironment.

Comparing routes of delivery for nanoliposomal irinotecan shows superior anti-tumor activity of local administration in treating intracranial glioblastoma xenografts

BACKGROUND

Liposomal drug packaging is well established as an effective means for increasing drug half-life, sustaining drug activity, and increasing drug efficacy, whether administered locally or distally to the site of disease. However, information regarding the relative effectiveness of peripheral (distal) versus local administration of liposomal therapeutics is limited. This issue is of importance with respect to the treatment of central nervous system cancer, for which the blood-brain barrier presents a significant challenge in achieving sufficient drug concentration in tumors to provide treatment benefit for patients.

METHODS

We compared the anti-tumor activity and efficacy of a nanoliposomal formulation of irinotecan when delivered peripherally by vascular route with intratumoral administration by convection-enhanced delivery (CED) for treating intracranial glioblastoma xenografts in athymic mice.

RESULTS

Our results show significantly greater anti-tumor activity and survival benefit from CED of nanoliposomal irinotecan. In 2 of 3 efficacy experiments, there were animal subjects that experienced apparent cure of tumor from local administration of therapy, as indicated by a lack of detectable intracranial tumor through bioluminescence imaging and histopathologic analysis. Results from investigating the effectiveness of combination therapy with nanoliposomal irinotecan plus radiation revealed that CED administration of irinotecan plus radiation conferred greater survival benefit than did irinotecan or radiation monotherapy and also when compared with radiation plus vascularly administered irinotecan.

CONCLUSIONS

Our results indicate that liposomal formulation plus direct intratumoral administration of therapeutic are important for maximizing the anti-tumor effects of irinotecan and support clinical trial evaluation of this therapeutic plus route of administration combination.

Co-culture of mechanically injured cartilage with joint capsule tissue alters chondrocyte expression patterns and increases ADAMTS5 production

We studied changes in chondrocyte gene expression, aggrecan degradation, and aggrecanase production and activity in normal and mechanically injured cartilage co-cultured with joint capsule tissue. Chondrocyte expression of 21 genes was measured at 1, 2, 4, 6, 12, and 24h after treatment; clustering analysis enabled identification of co-expression profiles. Aggrecan fragments retained in cartilage and released to medium and loss of cartilage sGAG were quantified. Increased expression of MMP-13 and ADAMTS4 clustered with effects of co-culture, while increased expression of ADAMTS5, MMP-3, TGF-beta, c-fos, c-jun clustered with cartilage injury. ADAMTS5 protein within cartilage (immunohistochemistry) increased following injury and with co-culture. Cartilage sGAG decreased over 16-days, most severely following injury plus co-culture. Cartilage aggrecan was cleaved at aggrecanase sites in the interglobular and C-terminal domains, resulting in loss of the G3 domain, especially after injury plus co-culture. Together, these results support the hypothesis that interactions between injured cartilage and other joint tissues are important in matrix catabolism after joint injury.

Therapeutically targeting ErbB3: a key node in ligand-induced activation of the ErbB receptor-PI3K axis

The signaling network downstream of the ErbB family of receptors has been extensively targeted by cancer therapeutics; however, understanding the relative importance of the different components of the ErbB network is nontrivial. To explore the optimal way to therapeutically inhibit combinatorial, ligand-induced activation of the ErbB-phosphatidylinositol 3-kinase (PI3K) axis, we built a computational model of the ErbB signaling network that describes the most effective ErbB ligands, as well as known and previously unidentified ErbB inhibitors. Sensitivity analysis identified ErbB3 as the key node in response to ligands that can bind either ErbB3 or EGFR (epidermal growth factor receptor). We describe MM-121, a human monoclonal antibody that halts the growth of tumor xenografts in mice and, consistent with model-simulated inhibitor data, potently inhibits ErbB3 phosphorylation in a manner distinct from that of other ErbB-targeted therapies. MM-121, a previously unidentified anticancer therapeutic designed using a systems approach, promises to benefit patients with combinatorial, ligand-induced activation of the ErbB signaling network that are not effectively treated by current therapies targeting overexpressed or mutated oncogenes.

Gene expression profiles of human chondrocytes during passaged monolayer cultivation

Chondrocyte phenotype has been shown to dedifferentiate during passaged monolayer cultivation. Hence, we have investigated the expression profile of 27 chondrocyte-associated genes from both osteoarthritic cartilage tissue and healthy passaged human articular chondrocytes by quantitative real-time PCR. Our results indicate that the gene expression levels of matrix proteins and proteases in chondrocytes from monolayer culture decrease compared with those from cartilage tissue, while monolayer cultured chondrocytes from normal and osteoarthritic cartilage exhibit similar gene expression patterns. However, chondrocytic gene expression profiles were differentially altered at various stages of passage. The expression of the matrix proteins aggrecan, type II collagen, and fibromodulin inversely correlated with increasing passage number, while fibronectin and link protein exhibited a marked increase with passage. The expression of matrix proteinases MMP-3/9/13 and ADAMTS-4/5 decreased with passage, whereas proteinase inhibitors TIMP-2/3 were elevated. The cytokine IL-1 also showed increased expression with monolayer chondrocyte culture, while IGF-1 expression levels were diminished. No significant changes in TGF-beta, or the chondrogenic transcription factors Sox-9, c-fos, or c-jun were observed. Our data indicates that cultured chondrocytes undergo dedifferentiation during monolayer culture, although the gene expression level of transcription factors necessary for chondrogenesis remains unchanged. This data may prove important for the future development of more specific and efficacious cultivation techniques for human articular chondrocyte-based therapies.

Systems biology and combination therapy in the quest for clinical efficacy

Combinatorial control of biological processes, in which redundancy and multifunctionality are the norm, fundamentally limits the therapeutic index that can be achieved by even the most potent and highly selective drugs. Thus, it will almost certainly be necessary to use new 'targeted' pharmaceuticals in combinations. Multicomponent drugs are standard in cytotoxic chemotherapy, but their development has required arduous empirical testing. However, experimentally validated numerical models should greatly aid in the formulation of new combination therapies, particularly those tailored to the needs of specific patients. This perspective focuses on opportunities and challenges inherent in the application of mathematical modeling and systems approaches to pharmacology, specifically with respect to the idea of achieving combinatorial selectivity through use of multicomponent drugs.

Shear and Compression Differentially Regulate Clusters of Functionally Related Temporal Transcription Patterns in Cartilage Tissue

Chondrocytes are subjected to a variety of biophysical forces and flows during physiological joint loading, including mechanical deformation, fluid flow, hydrostatic pressure, and streaming potentials; however, the role of these physical stimuli in regulating chondrocyte behavior is still being elucidated. To isolate the effects of these forces, we subjected intact cartilage explants to 1-24 h of continuous dynamic compression or dynamic shear loading at 0.1 Hz. We then measured the transcription levels of 25 genes known to be involved in cartilage homeostasis using real-time PCR and compared the gene expression profiles obtained from dynamic compression, dynamic shear, and our recent results on static compression amplitude and duration. Using clustering analysis, we determined that transcripts for proteins with similar function had correlated responses to loading. However, the temporal expression patterns were strongly dependent on the type of loading applied. Most matrix proteins were up-regulated by 24 h of dynamic compression or dynamic shear, but down-regulated by 24 h of 50% static compression, suggesting that cyclic matrix deformation is a key stimulator of matrix protein expression. Most matrix proteases were up-regulated by 24 h under all loading types. Transcription factors c-Fos and c-Jun maximally responded within 1 h to all loading types. Pre-incubating cartilage explants with either a chelator of intracellular calcium or an inhibitor of the cyclic AMP pathway demonstrated the involvement of both pathways in transcription induced by dynamic loading.

Mechanical injury of cartilage explants causes specific time-dependent changes in chondrocyte gene expression

OBJECTIVE

Joint injury in young adults leads to an increased risk of developing osteoarthritis (OA) later in life. This study was undertaken to determine if injurious mechanical compression of cartilage explants results in changes at the level of gene transcription that may lead to subsequent degradation of the cartilage.

METHODS

Cartilage was explanted from the femoropatellar groove of newborn calves. Levels of messenger RNA encoding matrix molecules, proteases, their natural inhibitors, transcription factors, and cytokines were assessed in free swelling control cultures as compared with cartilage cultures at 1, 2, 4, 6, 12, and 24 hours after application of a single injurious compression.

RESULTS

Gene-expression levels measured in noninjured, free swelling cartilage varied over 5 orders of magnitude. Matrix molecules were the most highly expressed of the genes tested, while cytokines, matrix metalloproteinases (MMPs), aggrecanases (ADAMTS-5), and transcription factors showed lower expression levels. Matrix molecules showed little change in expression after injurious compression, whereas MMP-3 increased approximately 250-fold, ADAMTS-5 increased approximately 40-fold, and tissue inhibitor of metalloproteinases 1 increased approximately 12-fold above the levels in free swelling cultures. Genes typically used as internal controls, GAPDH and beta-actin, increased expression levels approximately 4-fold after injury, making them unsuitable for use as normalization genes in this study. The expression levels of tumor necrosis factor alpha and interleukin-1beta, cytokines known to be involved in the progression of OA, did not change in the chondrocytes after injury.

CONCLUSION

Changes in the level of gene expression after mechanical injury are gene specific and time dependent. The quantity of specific proteins may be altered as a result of these changes in gene expression, which may eventually lead to degradation at the tissue level and cause a compromise in cartilage structure and function.

Mechanical Compression of Cartilage Explants Induces Multiple Time-dependent Gene Expression Patterns and Involves Intracellular Calcium and Cyclic AMP

Chondrocytes are influenced by mechanical forces to remodel cartilage extracellular matrix. Previous studies have demonstrated the effects of mechanical forces on changes in biosynthesis and mRNA levels of particular extracellular matrix molecules, and have identified certain signaling pathways that may be involved. However, the broad extent and kinetics of mechano-regulation of gene transcription has not been studied in depth. We applied static compressive strains to bovine cartilage explants for periods between 1 and 24 h and measured the response of 28 genes using real time PCR. Compression time courses were also performed in the presence of an intracellular calcium chelator or an inhibitor of cyclic AMP-activated protein kinase A. Cluster analysis of the data revealed four main expression patterns: two groups containing either transiently up-regulated or duration-enhanced expression profiles could each be subdivided into genes that did or did not require intracellular calcium release and cyclic AMP-activated protein kinase A for their mechano-regulation. Transcription levels for aggrecan, type II collagen, and link protein were up-regulated approximately 2-3-fold during the first 8 h of 50% compression and subsequently down-regulated to levels below that of free-swelling controls by 24 h. Transcription levels of matrix metalloproteinases-3, -9, and -13, aggrecanase-1, and the matrix protease regulator cyclooxygenase-2 increased with the duration of 50% compression 2-16-fold by 24 h. Thus, transcription of proteins involved in matrix remodeling and catabolism dominated over anabolic matrix proteins as the duration of static compression increased. Immediate early genes c-fos and c-jun were dramatically up-regulated 6-30-fold, respectively, during the first 8 h of 50% compression and remained up-regulated after 24 h.

Real-time detection technique for Doppler optical coherence tomography

We propose and demonstrate a novel detection technique, based on a modified electronic phase-locked loop, for Doppler optical coherence tomography. The technique permits real-time simultaneous reflectivity and continuous, bidirectional velocity mapping in turbid media over a wide velocity range with minimal sensitivity penalty compared with conventional optical coherence tomography, which is a major advance over current postprocessing and discrete parallel detection techniques.

Early mobilization following angioplasty

AIM

To assess the incidence of puncture site complications in in-patients undergoing early mobilization following angioplasty with a view to performing day case angioplasty.

MATERIALS AND METHODS

One hundred and twenty-eight patients undergoing peripheral and renal angioplasty using a sheath size of up to 6 French were recruited prospectively. The mobilization protocol consisted of supine bed rest for 2 h, followed by gradual mobilization, so that the patient was ambulant 4 h after the procedure. Mobilization was delayed if clinically appropriate. Puncture sites were scored for discomfort, paraesthesia, visible bruising and palpable haematoma after groin compression and the following morning.

RESULTS

One hundred and forty-four puncture sites were studied. There were 44 haematomas in total, of which 37 (26%) were less than 2.5 cm and seven (4.9%) were between 2.5 cm and 7.5 cm. Four patients (2.8%) had visible bruising greater than 7.5 cm. No patient assessed discomfort higher than moderate at any stage. Mobilization was delayed in 15 patients. In 11 this was due to puncture site oozing, haematoma in one, two were hypertensive and one required surgery for limb ischaemia. All complications occurred within 4 h of angioplasty. No patient required surgery or transfusion for haemorrhagic complications.

CONCLUSION

Mobilization at 4 h was successful in 90% of cases but 10% require more prolonged bed rest. No delayed complications occurred. These results suggest that day case angioplasty is feasible in most cases.Butterfield, J. S. (2000). Clinical Radiology55, 874-877

The use of TIPS to control bleeding caput medusae

Two patients with cirrhosis and portal hypertension had persistent bleeding from caput medusae and ascites. Transjugular intrahepatic portosystemic shunt (TIPS) resulted in regression of the caput medusae and ascites in both cases.

The callosal-septal interface lesion in multiple sclerosis: effect of sequence and imaging plane

We examined the effect of imaging plane and sequence on the demonstration of lesions at the callosal-septal interface (CSI) by magnetic resonance imaging in 20 patients with known multiple sclerosis. Variable-echo-(VE) T2- and proton density (PD) weighted images were performed in coronal axial and sagittal planes. Sagittal gradient echo (GE) T2- and PD-weighted images were also performed. Lesions at the CSI were seen in all patients and were all demonstrated on both sagittal and coronal VE images. Sagittal PD-weighted GE images were slightly less sensitive but showed good overall agreement with sagittal VE. Axial VE and sagittal T2-weighted GE images demonstrated CSI lesions poorly.

Isolated splenic metastases from colon carcinoma

It is generally accepted that splenic metastases from colorectal carcinoma occur concurrently with widespread dissemination of the tumor. The case reviewed is notable for its long disease-free interval, isolated splenic metastasis and favorable-outcome postsplenectomy. It represents the fourth case report in the English literature of surgical resection for an isolated splenic metastasis from colorectal carcinoma.

CT appearances of haematomas in the corpus callosum in patients with subarachnoid haemorrhage

Corpus callosum haematoma is a rare feature in subarachnoid haemorrhage (SAH), which may result from aneurysms of the anterior communicating artery (ACoA) or pericallosal artery (PCA). In 348 patients with aneurysmal SAH, bleeding from ACoA aneurysms in 88 cases produced no abnormality on CT in 7. Blood in the cistern of the lamina terminalis was the most frequent abnormality (76/88); haematomas of the septum pellucidum, confined to patients with ACoA aneurysms, were seen in 26 (30%). Rupture of PCA aneurysms in 12 patients gave rise to blood in the pericallosal cistern, anterior interhemispheric fissure and cistern of the lamina terminalis in 11. There was no blood in the septum pellucidum or the ventricular system in any case, but haematomas in the corpus callosum occurred in 8 (67%). In all of these, blood extended into the anterodorsal aspect of the callosum and spread posteriorly along its dorsal border. An identical, supracallosal pattern was seen in 2 patients (2.5%) with ACoA aneurysms, in whom haemorrhage was more extensive, with a large frontal lobe haematoma extending up from the cistern of the lamina terminalis in 1 and a haematoma of the septum pellucidum, with intraventricular extension in the other. In 8 patients (9%) with ACoA aneurysms a corpus callosum haematoma appeared to result from passage of blood up through the cistern of the lamina terminalis into the septum pellucidum and thence into the ventral aspect of the anterior corpus callosum; blood was present within the cistern, the septum and the ventricles.

Bronchogenic cysts above and below the diaphragm: report of eight cases

Bronchogenic cysts are developmental foregut anomalies usually located within the mediastinum. Although typically asymptomatic, infection or compression of adjacent structures may become prominent. Surgical excision is recommended to establish diagnosis, alleviate symptoms if present, and prevent future complications. We report our recent experience with bronchogenic cysts including 7 located within the mediastinum and a rare instance of a cyst below the diaphragm.