Olav Engebråten

Metabolic biomarkers for response to PI3K inhibition in basal-like breast cancer

IntroductionThe phosphatidylinositol 3-kinase (PI3K) pathway is frequently activated in cancer cells through numerous mutations and epigenetic changes. The recent development of inhibitors targeting different components of the PI3K pathway may represent a valuable treatment alternative. However, predicting efficacy of these drugs is challenging, and methods for therapy monitoring are needed. Basal-like breast cancer (BLBC) is an aggressive breast cancer subtype, frequently associated with PI3K pathway activation. The objectives of this study were to quantify the PI3K pathway activity in tissue sections from xenografts representing basal-like and luminal-like breast cancer before and immediately after treatment with PI3K inhibitors, and to identify metabolic biomarkers for treatment response.MethodsTumor-bearing animals (n = 8 per treatment group) received MK-2206 (120 mg/kg/day) or BEZ235 (50 mg/kg/day) for 3 days. Activity in the PI3K/Akt/mammalian target of rapamycin pathway in xenografts and human biopsies was evaluated using a novel method for semiquantitative assessment of Aktser473 phosphorylation. Metabolic changes were assessed by ex vivo high-resolution magic angle spinning magnetic resonance spectroscopy.ResultsUsing a novel dual near-infrared immunofluorescent imaging method, basal-like xenografts had a 4.5-fold higher baseline level of pAktser473 than luminal-like xenografts. Following treatment, basal-like xenografts demonstrated reduced levels of pAktser473 and decreased proliferation. This correlated with metabolic changes, as both MK-2206 and BEZ235 reduced lactate concentration and increased phosphocholine concentration in the basal-like tumors. BEZ235 also caused increased glucose and glycerophosphocholine concentrations. No response to treatment or change in metabolic profile was seen in luminal-like xenografts. Analyzing tumor sections from five patients with BLBC demonstrated that two of these patients had an elevated pAktser473 level.ConclusionThe activity of the PI3K pathway can be determined in tissue sections by quantitative imaging using an antibody towards pAktser473. Long-term treatment with MK-2206 or BEZ235 resulted in significant growth inhibition in basal-like, but not luminal-like, xenografts. This indicates that PI3K inhibitors may have selective efficacy in basal-like breast cancer with increased PI3K signaling, and identifies lactate, phosphocholine and glycerophosphocholine as potential metabolic biomarkers for early therapy monitoring. In human biopsies, variable pAktser473 levels were observed, suggesting heterogeneous PI3K signaling activity in BLBC.

PCI-enhanced adenoviral transduction employs the known uptake mechanism of adenoviral particles

The development of methods for efficient and specific delivery of therapeutic genes into target tissues is an important issue for further development of in vivo gene therapy. In the present study, the physical targeting technique, photochemical internalization (PCI), has been used together with adenovirus. The combination of PCI and adenoviral transduction has previously been shown to be favorable compared to adenovirus used alone, and the aim of this study was to verify the role of the adenoviral receptors and identify the uptake pathway used by adenoviral particles in photochemically treated cells. All examined cell lines showed augmented transduction efficiency after PCI-treatment, with a maximum of 13-fold increase in transgene expression compared to conventionally infected cells. Blocking of CAR induced a complete inhibition of PCI-enhanced transgene expression. However, photochemical treatment managed to enhance the transduction efficiency of the retargeted virus AdRGD-GFP showing also that the virus-CAR interaction is not vital for obtaining a photochemical effect on adenoviral transduction. Blocking the αV-integrins reduced the gene expression significantly in photochemically treated cells. Subjecting HeLa cells expressing negative mutant-dynamin to light treatment after infection gave no significant increase in gene transfer, while the gene transfer were enhanced seven-fold in cells with wild-type dynamin. Furthermore, chlorpromazine inhibited photochemical transduction in a dose-dependent manner, whereas Filipin III had no effect on the gene transfer. In summary, the data presented imply that adenoviral receptor binding is important and clathrin-mediated endocytosis is the predominant uptake mechanism for adenoviral particles in photochemically treated cells.

Dynamic 18F-FDG-PET for monitoring treatment effect following anti-angiogenic therapy in triple-negative breast cancer xenografts

Abstract Introduction. Dynamic 18F-FDG PET allows the study of glucose distribution in tissues as a function of time and space. Using pharmacokinetics, the temporal uptake pattern of 18F-FDG may be separated into components reflecting perfusion and metabolism. Bevacizumab is an angiogenesis inhibitor which prevents the growth of new blood vessels, and may potentially lead to normalization of the blood circulation in the tumor. The purpose of the study was to explore the use of dynamic PET as a tool for monitoring treatment effect, reflected by changes in perfusion and metabolism. Materials and Methods. Twelve athymic nude mice, bearing the bilateral triple-negative human breast cancer xenograft MAS98.12 were treated with bevacizumab (5 mg/kg i.p.). Dynamic PET data was acquired prior to and 24 and 72 hours after treatment for 1 hour after injection of 10 MBq 18F-FDG and fitted with a FDG two-tissue compartment model. The changes in the rate constants k1, k3, MRFDG and the vascular fraction νB were assessed. To evaluate the effect of treatment regimes, 30 mice, randomized in 5 groups, received either vehicle (0.9% NaCl), bevacizumab (5 mg/kg i.p.), doxorubicin (8 mg/kg i.v.) or bevacizumab and doxorubicin either together, or doxorubicin 24 hours after bevacizumab treatment. Tumor volume was measured twice a week. Results. The perfusion-related rate parameter k1 and the metabolic rate constant k3 decreased significantly 24 hours after treatment. This decrease was followed by an increase, albeit non-significant, at 72 hours post treatment. Doxorubicin given 24 hours after bevacizumab showed less antitumor effect compared to concomitant treatment. Conclusions. Dynamic PET can detect changes in tumor perfusion and metabolism following anti-angiogenic therapy in mouse xenograft models. Longitudinal dynamic PET, used to assess the efficacy of anti-angiogenic treatment, can identify the time frame of potential tumor vasculature re-normalization and allow optimal timing of supplementary therapy (radiation or chemotherapy).

Targeting inhibitor of apoptosis proteins in combination with dacarbazine or TRAIL in melanoma cells

Melanoma is a highly aggressive malignant tumor with an exceptional ability to develop resistance and no curative therapy is available for patients with distant metastatic disease. The inhibitor of apoptosis protein (IAP) family has been related to therapy resistance in cancer. We examined the importance of the IAPs in the resistance to the commonly used chemotherapeutic agent dacarbazine (DTIC) and the apoptosis inducer TRAIL (TNF-related apoptosis inducing ligand) in malignant melanoma. The data presented show that the expression of IAPs is universal, concomitant and generally high in melanoma cell lines and in patient samples. Depleting IAP expression by siRNA tended to reduce cell viability, with XIAP reduction being the most efficient in all four cell lines examined (FEMX-1, LOX, SKMEL-28 and WM115). The combined treatment of XIAP siRNA and DTIC showed a weak improvement in two of four cell lines, while all four cell lines showed enhanced sensitivity towards TRAIL (AdhCMV-TRAIL) after XIAP depletion. In addition, cIAP-1, cIAP-2 and survivin down-regulation sensitized to TRAIL treatment in several of the cell lines. Cells exposed to TRAIL and XIAP siRNA showed increased DNA-fragmentation and cleavage of Bid, procaspase-8, -9, -7 and -3 and PARP, and change in the balance between pro- and anti-apoptotic proteins, indicating an enhanced level of apoptosis. Furthermore, the combined treatment reduced the ability of melanoma cells to engraft and form tumors in mice, actualizing the combination for future therapy of malignant melanoma.

Human malignant melanoma harbours a large fraction of highly clonogenic cells that do not express markers associated with cancer stem cells

Department of Tumour Biology, Oslo University Hospital Radiumhospital, Oslo, Norway Department of Pathology, Oslo University Hospital Radiumhospital, Oslo, Norway Faculty Division, The Norwegian Radium Hospital, University of Oslo, Oslo, Norway Department of Surgery, Oslo University Hospital Radiumhospital, Oslo, Norway Department of Clinical Cancer Research, Oslo University Hospital Radiumhospital, Oslo, Norway Correspondence Lina Prasmickaite, e-mail: linap@rr-research.no

Quantitative 31P HR-MAS MR spectroscopy for detection of response to PI3K/mTOR inhibition in breast cancer xenografts

Phospholipid metabolites are of importance in cancer studies, and have been suggested as candidate metabolic biomarkers for response to targeted anticancer drugs. The purpose of this study was to develop a phosphorus (31P) high resolution magic angle spinning magnetic resonance spectroscopy protocol for quantification of phosphorylated metabolites in intact cancer tissue.

In Vivo 31P magnetic resonance spectroscopic imaging (MRSI) for metabolic profiling of human breast cancer xenografts

To study cancer associated with abnormal metabolism of phospholipids, of which several have been proposed as biomarkers for malignancy or to monitor response to anticancer therapy. We explored 3D 31P magnetic resonance spectroscopic imaging (MRSI) at high magnetic field for in vivo assessment of individual phospholipids in two patient‐derived breast cancer xenografts representing good and poor prognosis (luminal‐ and basal‐like tumors).

In vivo 31P MRSI for metabolic profiling of human breast cancer xenografts

To study cancer associated with abnormal metabolism of phospholipids, of which several have been proposed as biomarkers for malignancy or to monitor response to anticancer therapy. We explored 3D 31P magnetic resonance spectroscopic imaging (MRSI) at high magnetic field for in vivo assessment of individual phospholipids in two patient‐derived breast cancer xenografts representing good and poor prognosis (luminal‐ and basal‐like tumors).

Abstract P1-08-21: Detection and monitoring of circulating endothelial cells, circulating tumor cells and disseminated tumor cells during neoadjuvant breast cancer treatment including bevacizumab

Background: Results from studies with bevacizumab in addition to traditional neoadjuvant therapy (NAT) indicate a need for predictive biomarkers. As a sub-study of the NeoAva study (a neoadjuvant study), the aim was to investigate the potential association between the presence of circulating endothelial cells (CECs) in peripheral blood (PB), circulating tumor cells (CTCs) in PB and disseminated tumor cells (DTCs) in bone marrow (BM) at different time points during NAT +/- bevacizumab and at one year follow-up, and therapy response. Patients and methods: A total of 150 HER2-negative patients with cT2-4 (≥ 2.5cm) N0-3 M0 status were randomized to receive NAT with or without bevacizumab. In this sub-study, 90 patients have so far been analyzed. Of these, 82 received chemotherapy (FEC100→taxane) and 8 received endocrine therapy (letrozole) + / - bevacizumab. Therapy response was evaluated according to the RECIST criteria and achievement of pathological complete response (pCR). Number of CECs, CTCs and DTCs were assessed at baseline after 12 weeks, at surgery (after 24 weeks) and at one year follow-up. Blood samples were analyzed by CellSearch® to assess CEC and CTC counts. The detection of DTCs was performed by immunocytochemical analysis of 2 × 106 BM mononuclear cells. Results: The pathological complete response rate was 10 out of 90 (11.1%), eight of these patients received bevacizumab. For bevacizumab-treated patients with a change in CEC counts from baseline to time of surgery below median change (27 CECs), 35% (6/17) achieved pCR compared to 6% (1/18) in the group with a CEC count-increase above median change (p = 0.035). The corresponding pCR rates for patients not receiving bevacizumab (median CEC change 131 CECs) were 0% (0/15) and 13% (2/14), respectively. Stepwise testing of thresholds for CEC changes in the bevacizumab-arm revealed significant associations to pCR for change-values between 20 and 40. CTC- and DTC-status or -changes were not associated with tumor response or CEC changes. Conclusion: The presented results indicate that the level of change in the number of circulating endothelial cells during neoadjuvant therapy including bevacizumab is associated with the pathological complete response rate in breast cancer patients. This supports additional testing of CECs as a surrogate marker for response to this treatment. The analyses will be up-dated with results from the rest of the included patients. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-08-21.

The longitudinal transcriptional response to neoadjuvant chemotherapy with and without bevacizumab in breast cancer

Purpose: Chemotherapy-induced alterations to gene expression are due to transcriptional reprogramming of tumor cells or subclonal adaptations to treatment. The effect on whole-transcriptome mRNA expression was investigated in a randomized phase II clinical trial to assess the effect of neoadjuvant chemotherapy with the addition of bevacizumab. Experimental Design: Tumor biopsies and whole-transcriptome mRNA profiles were obtained at three fixed time points with 66 patients in each arm. Altogether, 358 specimens from 132 patients were available, representing the transcriptional state before treatment start, at 12 weeks and after treatment (25 weeks). Pathologic complete response (pCR) in breast and axillary nodes was the primary endpoint. Results: pCR was observed in 15 patients (23%) receiving bevacizumab and chemotherapy and 8 patients (12%) receiving only chemotherapy. In the estrogen receptor–positive patients, 11 of 54 (20%) treated with bevacizumab and chemotherapy achieved pCR, while only 3 of 57 (5%) treated with chemotherapy reached pCR. In patients with estrogen receptor–positive tumors treated with combination therapy, an elevated immune activity was associated with good response. Proliferation was reduced after treatment in both treatment arms and most pronounced in the combination therapy arm, where the reduction in proliferation accelerated during treatment. Transcriptional alterations during therapy were subtype specific, and the effect of adding bevacizumab was most evident for luminal-B tumors. Conclusions: Clinical response and gene expression response differed between patients receiving combination therapy and chemotherapy alone. The results may guide identification of patients likely to benefit from antiangiogenic therapy. Clin Cancer Res; 23(16); 4662–70. ©2017 AACR.