Quantitative tumor apoptosis imaging using technetium-99m-HYNIC annexin V single photon emission computed tomography

Translational imaging: imaging of apoptosis

Since its original description in 1972, apoptosis or programmed cell death has been recognized as the major pathway by which the body precisely regulates the number and type of its cells as part of normal embryogenesis, development, and homeostasis. Later it was found that apoptosis was also involved in the pathogenesis of a number of human diseases, cell immunity, and the action of cytotoxotic drugs and radiation therapy in cancer treatment. As such, the imaging of apoptosis with noninvasive techniques such as with radiotracers, including annexin V and lipid proton magnetic resonance spectroscopy, may have a wide range of clinical utility in both the diagnosis and monitoring therapy of a wide range of human disorders. In this chapter we review the basic biochemical and morphologic features of apoptosis and the methods developed thus far to image this complex process in humans.

99mTc-HYNIC-rh-annexin-V scintigraphy: visual and quantitative evaluation of early treatment-induced apoptosis to predict treatment outcome

AIM

To determine the reliability of visual analysis of 99mTc-HYNIC-rh-annexin-V tumour uptake (ATU) compared to quantitative tracer uptake evaluation.

METHODS

Thirty-eight patients (22 male, 16 female, mean age 57) with histologically proved lymphoma (n=31), non-small cell lung cancer (NSCLC) (n=4) and head and neck squamous cell carcinoma (H&NSCC) (n=3) were examined. 99mTc-HYNIC-rh-annexin-V scintigraphy (TAS) was acquired before and within 2 days after the start of anti-cancer treatment. Maximal counts per pixel in the tumour volume (Cmax) were calculated for every target lesion. To match the quantitative and visual ATU, both were expressed as a four-grade score. Cmax as percentages of baseline values: grade 1, decrease >25%; grade 0, 1-25% decrease; grade 1, 1-25% increase; grade 2, >25% increase. Visual analysis: 0=absent, 1=weak, 2=moderate, 3=intense. Intra-observer and inter-observer variability and methodological agreement between visual and quantitative evaluation of ATU was expressed by computing Cohen's kappa statistics.

RESULTS

A statistically highly significant correlation was found between the changes in ATU and therapy outcome: r=0.97 (P<0.0001) and r=0.99 (P<0.0001) for visual and quantitative analysis, respectively. Good intra-observer reproducibility, with a high kappa of 0.82 for observer 1 and a kappa of 0.90 for observer 2, was determined. Inter-observer variability was 0.82.

CONCLUSION

Visual evaluation of ATU after image co-registration appears to be a reliable and reproducible method for preliminary assessment of early treatment-induced apoptosis.

Assessment of neuroprotection in the retina with DARC

Currently, assessment of new drug efficacy in glaucoma relies on conventional perimetry to monitor visual field changes. However, visual field defects cannot be detected until 20-40% of retinal ganglion cells (RGCs), the key cells implicated in the development of irreversible blindness in glaucoma, have been lost. We have recently developed a new, noninvasive real-time imaging technology, which is named DARC (detection of apoptosing retinal cells), to visualize single RGC undergoing apoptosis, the earliest sign of glaucoma. Utilizing fluorescently labeled annexin 5 and confocal laser scanning ophthalmoscopy, DARC enables evaluation of treatment effectiveness by monitoring RGC apoptosis in the same living eye over time. Using DARC, we have assessed different neuroprotective therapies in glaucoma-related animal models and demonstrated DARC to be a useful tool in screening neuroprotective strategies. DARC will potentially provide a meaningful clinical end point that is based on the direct assessment of the RGC death process, not only being useful in assessing treatment efficacy, but also leading to the early identification of patients with glaucoma. Clinical trials of DARC in glaucoma patients are due to start in 2008.

[Molecular imaging with new PET tracers]

In the recent years, positron emission tomography (PET) has gained more and more importance, especially in oncology for primary staging, as well as for response evaluation. The glucose analogon (18)F-FDG is the most widely used tracer up to now. In this paper, we review the applications of newly developed, more specific PET tracers. These tracers allow for imaging of a variety of biological processes, such as hypoxia and proliferation. The expression of different receptors can be visualized, like the somatostatin receptor 2 and the integrin alphavbeta3. Moreover, gene expression can be imaged as well. While most of these approaches are currently in the first phases of clinical evaluation, imaging of hypoxia and proliferation might be integrated into the daily routine in the near future.

99mTc Hynic-rh-Annexin V scintigraphy for in vivo imaging of apoptosis in patients with head and neck cancer treated with chemoradiotherapy

Purpose

The purpose of this study was to determine the value of ^99mTc Hynic-rh-Annexin-V-Scintigraphy (TAVS), a non-invasive in vivo technique to demonstrate apoptosis in patients with head and neck squamous cell carcinoma.

Methods

TAVS were performed before and within 48 h after the first course of cisplatin-based chemoradiation. Radiation dose given to the tumour at the time of post-treatment TAVS was 6–8 Gy. Single-photon emission tomography data were co-registered to planning CT scan. Complete sets of these data were available for 13 patients. The radiation dose at post-treatment TAVS was calculated for several regions of interest (ROI): primary tumour, involved lymph nodes and salivary glands. Annexin uptake was determined in each ROI, and the difference between post-treatment and baseline TAVS represented the absolute Annexin uptake: Delta uptake (ΔU).

Results

In 24 of 26 parotid glands, treatment-induced Annexin uptake was observed. Mean ΔU was significantly correlated with the mean radiation dose given to the parotid glands (r = 0.59, p = 0.002): Glands that received higher doses showed more Annexin uptake. ΔU in primary tumour and pathological lymph nodes showed large inter-patient differences. A high correlation was observed on an inter-patient level (r = 0.71, p = 0.006) between the maximum ΔU in primary tumour and in the lymph nodes.

Conclusions

Within the dose range of 0–8 Gy, Annexin-V-scintigraphy showed a radiation-dose-dependent uptake in parotid glands, indicative of early apoptosis during treatment. The inter-individual spread in Annexin uptake in primary tumours could not be related to differences in dose or tumour volume, but the Annexin uptake in tumour and lymph nodes were closely correlated. This effect might represent a tumour-specific apoptotic response.

Tumor-specific positron emission tomography imaging in patients: [18F] fluorodeoxyglucose and beyond

Biochemical and molecular imaging of cancer using positron emission tomography (PET) plays an increasing role in the care of cancer patients. Most clinical work to date uses the glucose analogue [(18)F]fluorodeoxyglucose (FDG) to detect accelerated and aberrant glycolysis present in most tumors. Although clinical FDG PET has been used largely to detect and localize cancer, more detailed studies have yielded biological insights and showed the utility of FDG as a prognostic marker and as a tool for therapeutic response evaluation. As cancer therapy becomes more targeted and individualized, it is likely that PET radiopharmaceuticals other than FDG, aimed at more specific aspects of cancer biology, will also play a role in guiding cancer therapy. Clinical trials designed to test and validate new PET agents will need to incorporate rigorous quantitative image analysis and adapt to the evolving use of imaging as a biomarker and will need to incorporate cancer outcomes, such as survival into study design.

Prognostic value of 99mTc-HYNIC Annexin-V imaging in squamous cell carcinoma of the head and neck

PURPOSE

The purpose of the study was to report on the prognostic value of (99m)Tc-hydrazinonicotinamide (HYNIC) Annexin-V single-photon emission computed tomography (SPECT) imaging in patients suffering from primary squamous cell carcinoma of the head and neck.

METHODS

Twenty-nine patients diagnosed with a primary untreated head and neck squamous cell carcinoma were included in this study. In all patients, (99m)Tc-HYNIC Annexin-V scintigraphy SPECT was performed before treatment instigation. Tumour-to-background ratios (T/N) of the primary tumour, derived from reconstructed images, as well as clinical variables were obtained in all patients and related to patient outcome. Median follow-up was 22.6 months (range 4.1-55.8 months).

RESULTS

On univariate as well as multivariate analysis, only the (99m)Tc-HYNIC Annexin-V T/N ratio dichotomized using the group median as cutoff value (T/N ratio of 2) was predictive of recurrence-free survival (respectively, p = 0.0000 and 0.000). On univariate analysis, only lymph node status dichotomized according to N0 vs N1-N2-N3 disease and the (99m)Tc-HYNIC Annexin-V T/N ratio dichotomized using the group median as cutoff value (T/N ratio of 2) were predictive of overall survival (p = 0.0051 and 0.0000). When both factors were included in the multivariate model, both N status and the (99m)Tc-HYNIC Annexin-V T/N ratio showed an independent association with overall survival (p = 0.001 for lymph node status and 0.000 for dichotomized (99m)Tc-HYNIC Annexin-V T/N ratio).

CONCLUSION

(99m)Tc-HYNIC Annexin-V T/N ratios derived from SPECT provides independent prognostic information on disease-free survival and overall survival.

Cardiovascular molecular imaging of apoptosis

Introduction

Molecular imaging strives to visualise processes at the molecular and cellular level in vivo. Understanding these processes supports diagnosis and evaluation of therapeutic efficacy on an individual basis and thereby makes personalised medicine possible.

Apoptosis and molecular imaging

Apoptosis is a well-organised mode of cell suicide that plays a role in cardiovascular diseases (CVD). Apoptosis is associated with loss of cardiomyocytes following myocardial infarction, atherosclerotic plaque instability, congestive heart failure and allograft rejection of the transplanted heart. Thus, apoptosis constitutes an attractive target for molecular imaging of CVD. Our current knowledge about the molecular players and mechanisms underlying apoptosis offers a rich palette of potential molecular targets for molecular imaging. However, only a few have been successfully developed so far.

Aims

This review highlights aspects of the molecular machinery and biochemistry of apoptosis relevant to the development of molecular imaging probes. It surveys the role of apoptosis in four major areas of CVD and portrays the importance and future perspectives of apoptosis imaging. The annexin A5 imaging protocol is emphasised since it is the most advanced protocol to measure apoptosis in both preclinical and clinical studies.

In vivo targeting of dead tumor cells in a murine tumor model using a monoclonal antibody specific for the La autoantigen

PURPOSE

To investigate the potential of the La-specific monoclonal antibody (mAb) 3B9 as an in vivo tumor-targeting agent.

EXPERIMENTAL DESIGN

The murine EL4 lymphoma cell line was used for in vitro studies and the EL4 model in which apoptosis was induced with cyclophosphamide and etoposide was used for in vivo studies. In vitro studies compared 3B9 binding in the EL4 cell with that in its counterpart primary cell type of the thymocyte. For in vivo studies, 3B9 was intrinsically or extrinsically labeled with carbon-14 or 1,4,7,10-tetra-azacylododecane-N,N',N'',N''''-tetraacetic acid-indium-111, respectively, and biodistribution of the radiotracers was investigated in EL4 tumor-bearing mice, which were treated or not with chemotherapy.

RESULTS

La-specific 3B9 mAb bound EL4 cells rather than thymocytes, and binding was detergent resistant. 3B9 binding to dead EL4 cells in vitro was specific, rapid, and saturable. Significantly, more 3B9 bound dead EL4 tumor explant cells after host mice were treated with chemotherapy, which suggested that DNA damage induced 3B9 binding. Tumor binding of 3B9 in vivo was antigen specific and increased significantly after chemotherapy. Tumor accumulation of 3B9 peaked at approximately 50% of the injected dose per gram of tumor 72 h after chemotherapy and correlated with increased tumor cell death. Tumor/organ ratios of 3B9 biodistribution, which included the tumor/blood ratio, exceeded unity 48 or more hours after chemotherapy.

CONCLUSIONS

La-specific mAb selectively targeted dead tumor cells in vivo, and targeting was augmented by cytotoxic chemotherapy. This novel cell death radioligand may be useful both for radioimmunoscintigraphy and radioimmunotherapy.

Biochemical and in vivo characterization of a small, membrane-permeant, caspase-activatable far-red fluorescent peptide for imaging apoptosis

Apoptosis is an important process involved in diverse developmental pathways, homeostasis, and response to therapy for a variety of diseases. Thus, noninvasive methods to study regulation and to monitor cell death in cells and whole animals are desired. To specifically detect apoptosis in vivo, a novel cell-permeable activatable caspase substrate, TcapQ647, was synthesized and Km, kcat, and Ki values were biochemically characterized. Specific cleavage of TcapQ647 by effector caspases was demonstrated using a panel of purified recombinant enzyme assays. Of note, caspase 3 was shown to cleave TcapQ647 with a kcat 7-fold greater than caspase 7 and 16-fold greater than caspase 6. No evidence of TcapQ647 cleavage by initiator caspases was observed. In KB 3-1 or Jurkat cells treated with cytotoxic agents or C6-ceramide, TcapQ647 detected apoptosis in individual- and population-based fluorescent cell assays in an effector caspase inhibitor-specific manner. Further, only background fluorescence was observed in cells incubated with dTcapQ647, a noncleavable all d-amino acid control peptide. Finally, in vivo experiments demonstrated the utility of TcapQ647 to detect parasite-induced apoptosis in human colon xenograft and liver abscess mouse models. Thus, TcapQ647 represents a sensitive, effector caspase-specific far-red "smart" probe to noninvasively monitor apoptosis in vivo.

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. However, there are many challenges in the development and implementation of biomarkers that probably explain their disappointingly low implementation in phase I trials. The Pharmacodynamic/Pharmacokinetic Technologies Advisory committee of Cancer Research UK has found that submissions for phase I trials of new cancer drugs in the United Kingdom often lack detailed information about PK and/or PD endpoints, which leads to suboptimal information being obtained in those trials or to delays in starting the trials while PK/PD methods are developed and validated. Minimally invasive PK/PD technologies have logistic and ethical advantages over more invasive technologies. Here we review these technologies, emphasizing magnetic resonance spectroscopy and positron emission tomography, which provide detailed functional and metabolic information. Assays that measure effects of drugs on important biologic pathways and processes are likely to be more cost-effective than those that measure specific molecular targets. Development, validation, and implementation of minimally invasive PK/PD methods are encouraged.

Recent new approaches to the treatment of head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer in the world and affects 50,000 Americans annually. During the past 20 years, treatments for HNSCC have changed dramatically due largely to the advent of novel approaches such as combined modality therapy, as well as improvements in surgical and radiotherapeutic techniques. Ongoing advances in the multidisciplinary management of this complex and multivariate disease process are resulting in improved function, quality of life and survival. Here, we review state-of-the-art therapy and presents selected advances in the treatment of head and neck cancer.

In VivoImaging of Chemotherapy-Induced Apoptosis in Human Cancers

RATIONALE

Induction of apoptosis in sensitive tumor cells is the main mechanism of action of chemotherapy agents in human cancers. Also, the assessment of drug-induced apoptosis soon after chemotherapy may be an early predictor of treatment efficacy.

PATIENTS AND METHODS

A phase I/II study was prospectively conducted in 15 patients presenting with proven lung cancers (n = 10), breast cancers (n = 2), and lymphomas (n = 3) to assess the value of the (99m)Tc-radiolabeled recombinant human (rh) Annexin V for imaging apoptosis immediately after completion of the first course of chemotherapy. Early Annexin V findings post-chemotherapy (day+1, day+2) were also compared to the tumor status at 6 to 12 weeks post-treatment.

RESULTS

All lung and lymphoma patients with an increased tracer uptake post-treatment (n = 8) had either partial or complete tumor response. Five patients with no tracer uptake had progressive disease. However, two breast cancers had a response to treatment, although no significant tracer uptake was observed. Tumor response and survival time were significantly correlated with the (99m)Tc-labeled Annexin V uptake. No serious events related to tracer administration were noted.

CONCLUSION

: Preliminary results of this pilot study demonstrate the feasibility of the 99mTc-labeled Annexin V uptake for the in vivo imaging of apoptosis after one course of chemotherapy. If confirmed on larger series, these promising results may open new perspectives in the management of oncology patients.

New reagents for phosphatidylserine recognition and detection of apoptosis

The phospholipid bilayer surrounding animal cells is made up of four principle phospholipid components, phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), and sphingomyelin (SM). These four phospholipids are distributed between the two monolayers of the membrane in an asymmetrical fashion, with PC and SM largely populating the extracellular leaflet and PE and PS restricted primarily to the inner leaflet. Breakdown in this transmembrane phospholipid asymmetry is a hallmark of the early to middle stages of apoptosis. The consequent appearance of PS on the extracellular membrane leaflet is commonly monitored using dye-labeled Annexin V, a 36 kDa, Ca2+-dependent PS binding protein. Substitutes for Annexin V are described, including small molecules, nanoparticles, cationic liposomes, and other proteins that can recognize PS in a membrane surface. Particular attention is given to the use of these reagents for detecting apoptosis.

Functional comparison of annexin V analogues labeled indirectly and directly with iodine-124

We are interested in imaging cell death in vivo using annexin V radiolabeled with (124)I. In this study, [(124)I]4IB-annexin V and [(124)I]4IB-ovalbumin were made using [(124)I]N-hydroxysuccinimidyl-4-iodobenzoate prepared by iododestannylation of N-hydroxysuccinimidyl-4-(tributylstannyl)benzoate. [(124)I]4IB-annexin V binds to phosphatidylserine-coated microtiter plates and apoptotic Jurkat cells and accumulates in hepatic apoptotic lesions in mice treated with anti-Fas antibody, while [(124)I]4IB-ovalbumin does not. In comparison with (124)I-annexin V, [(124)I]4IB-annexin V has a higher rate of binding to phosphatidylserine in vitro, a higher kidney and urine uptake, a lower thyroid and stomach content uptake, greater plasma stability and a lower rate of plasma clearance. Binding of radioactivity to apoptotic cells relative to normal cells in vitro and in vivo appears to be lower for [(124)I]4IB-annexin V than for (124)I-annexin V.

MBP-annexin V radiolabeled directly with iodine-124 can be used to image apoptosis in vivo using PET

A noninvasive method of measuring programmed cell death in the tumors of cancer patients using positron-emission tomography (PET) would provide valuable information regarding their response to therapeutic intervention. Our strategy is to radiolabel annexin V, a protein that binds to phosphatidylserine moieties that are translocated to the external leaflet of plasma membranes during apoptosis. We developed a phosphatidylserine-ELISA capable of distinguishing wild type from point mutant annexin V that is known to have a lower phosphatidylserine binding affinity. A maltose-binding protein/annexin V chimera was synthesized and purified with high yield using amylose resin. We showed that it bound to phosphatidylserine in the ELISA as well as to that exposed on apoptotic Jurkat cells; therefore, it was used in the development of a method for radiolabeling annexin V using iodine radionuclides. MBP-annexin V retained its phosphatidylserine binding properties on direct iodination, but at high levels of oxidizing agents (iodogen and chloramine T), its specificity for phosphatidylserine was compromised. (124)I-MBP-annexin V was successfully used to image Fas-mediated hepatic cell death in BDF-1 mice using PET. In conclusion, we have shown that MBP-annexin V and the phosphatidylserine ELISA are useful tools for the development of methods for radiolabeling annexin V for PET imaging.

In vivo apoptosis detection with radioiodinated Annexin V in LoVo tumour-bearing mice following Tipifarnib (Zarnestra, R115777) farnesyltransferase inhibitor therapy

In this paper, the use of (123)I-Annexin V for the detection of farnesyltransferase inhibitor (FTI)-induced apoptosis in tumour-bearing athymic mice is described. In vitro binding assays on LoVo cells show time- and dosage-dependent (125)I-Annexin V binding upon treatment with Tipifarnib (Zarnestra, R115777), a selective and potent FTI. In vivo experiments using planar gamma scintigraphy on LoVo inoculated mice show a 40% increased (123)I-Annexin V uptake 8 h after a single oral administration of 100 mg/kg Tipifarnib in 20% beta-cyclodextrin in 0.1 M HCl, as well as after 3 days of twice daily treatments with the same dose. Ex vivo TUNEL assays, detecting end-stage apoptotic cells, correlate significantly with both in vitro and in vivo results. The percentage of necrosis is also increased by Tipifarnib treatment, but is too low to interfere with the (123)I-Annexin V uptake. It can be concluded that (123)I-Annexin V can be used to monitor Tipifarnib-induced apoptosis in LoVo xenograft tumours in athymic mice. Future applications might include the early prediction of FTI response and the selection of FTI-sensitive patients very shortly after treatment initiation. Subsequently, such patients would greatly benefit from a noninvasive and fast therapy evaluation.

Imaging beta-cell death with a near-infrared probe

Evidence exists for an essential role of beta-cell apoptosis in the pathology of type 1 and type 2 diabetes. Current methods for diabetes-associated apoptosis detection, however, suffer the drawbacks of relying on in situ-based strategies. In this study, we attempted to measure, both in vitro and ex vivo, levels of beta-cell apoptosis in diabetic mice using Cy5.5-labeled annexin V. We used streptozotocin-treated BALB/c mice and NOD mice of different ages as models of type 1 diabetes and db/db mice as a model of type 2 diabetes. With annexin V Cy5.5, we established differences in levels of apoptosis between diabetic and control animals. Intravenously administered annexin V Cy5.5 accumulated in pancreata of diabetic mice but not in nondiabetic controls. Furthermore, its localization was specific to apoptotic events within diabetic islets; its selectivity was supported by transferase-mediated dUTP nick-end labeling staining. Because annexin V defines an early marker of apoptosis and the developed probe is suitable for in vivo administration, it may provide a promising tool for real-time identification in intact animals of the earliest stages of diabetes-associated beta-cell death and for tracing the events that characterize the pathology of the disease.

Weaving single photon imaging into new drug development

The specific aim of this review is to assess the potential contribution of single photon emitting radiopharmaceutical technologies to new drug development. For each phase of therapeutic drug development, published literature was sought that shows single photon emitters can add value by quantifying pharmacokinetics, visualizing mechanisms of drug action, estimating therapeutic safety indices, or measuring dose-dependent pharmacodynamic effects. Not any published reports were found that describe using nuclear medicine techniques to help manage the progress of a new drug development program. As a consequence, most of the case in favor of weaving single photon imaging into the process had to be built on extrapolations from studies that showed feasibility post hoc. The strongest evidence of potential value was found for drug candidates that hope to influence diseases characterized by cell proliferation or cell death, particularly in the fields of oncology, cardiology, nephrology, and inflammation. Receptor occupancy studies were observed to occasionally offer unique advantages over analogous studies with positron emission tomography (PET). Enough hard data sets were found to justify the costs of using single photon imaging in a variety of new drug development paradigms.

In vivo imaging of apoptosis by 99mTc-Annexin V scintigraphy: visual analysis in relation to treatment response

BACKGROUND AND PURPOSE

Anticancer therapy induces apoptosis in a dose- and time-dependent fashion. (99m)Tc-Hynic-rh-Annexin V scintigraphy (TAVS) enables non-invasive in vivo imaging of treatment-induced apoptosis. We identified the visual patterns of (99m)Tc-Hynic-rh-Annexin V tumour uptake and related these to treatment response.

PATIENTS AND METHODS

Thirty-three patients with malignant lymphoma (n=26), leukaemia (n=1) NSCLC (n=5), H&NSCC (n=1), scheduled for radiotherapy (n=27), platinum-based chemotherapy (n=5) or concurrent chemoradiation (n=1), underwent TAVS before and early after the start of treatment. Planar and SPECT images were visually examined to assess changes in tumour (99m)Tc-Hynic-rh-Annexin V uptake. Twenty-nine patients were eligible for further analysis. Annexin V uptake before (U(baseline)) and early after (U(post)) the start of treatment was graded using a four-step scale: 0, absent; 1, weak; 2, moderate and 3, intense. The difference between these values (Delta U) was calculated and correlated to tumour response after therapy (Spearman rank correlation test).

RESULTS

Weak to moderate U(baseline) was detected in 13/15 patients with a complete response and U(post) was markedly increased in all these cases (Delta U range 1-3). Partial response (n=7) was associated with weak to moderate U(baseline) and a moderately increased U(post) (Delta U range 1-2). In patients with stable disease (n=5), U(baseline) was predominantly weak, without considerable changes in uptake after the start of treatment (Delta U range 0-1). Finally, in case of progressive disease (n=2), either no tumour uptake or a decrease in U(post) was detected (Delta U=-1). A statistically significant correlation was found between changes in (99m)Tc-Hynic-rh-Annexin V tumour uptake and clinical response (correlation coefficient=0.62; P<0.001).

CONCLUSIONS

Complete or partial tumour response was associated with a marked increase of (99m)Tc Hynic-rh-Annexin V accumulation early during treatment compared to baseline values. In case of stable or progressive disease, pretreatment scans demonstrated predominantly low (99m)Tc Hynic-rh-Annexin V tumour uptake and no significant increase early after treatment. These results indicate that TAVS might be useful as a predictive test for treatment response.

Nuclear medicine in the era of genomics and proteomics: lessons from annexin V

In the past decade, genomics and proteomics have begun to develop many new targets for potential diagnostic and therapeutic agents. Among the life sciences, nuclear medicine is also deeply involved in the field of clinical investigation. Experience with radiolabeled annexin V highlights the many steps required to translate a good basic-science concept into the clinical setting. This model also emphasizes the value of synergy between basic and medical specialties in developing and optimizing a clinically useful product initially derived from basic investigation.

Intraobserver, interobserver, and day-to-day reproducibility of quantitative 99mTc-HYNIC annexin-V imaging in head and neck carcinoma

RATIONALE

For clinical application, a sufficient reproducibility of 99mTc-HYNIC annexin-V quantitative uptake measurements must be demonstrated to allow a study of cell-death changes induced by chemotherapy over time and intersubject. Thus, the aim of this study was to estimate the intra-, inter-, and day-to-day reproducibility of quantitative 99mTc-HYNIC annexin-V tumor uptake values in patients suffering from head and neck carcinomas.

METHODS

Thirteen (13) patients suffering from clinically suspected, histologically confirmed squamous head and neck carcinomas were prospectively included in the study. All patients were scheduled to undergo a spiral computed tomography scan and two 99mTc-HYNIC annexin-V scintigraphies within 3-5 days from each other, referred to as day 1 and day 2 of scintigraphy. The percentage of uptake of the injected dose of 99mTc-HYNIC annexin-V in tumor lesions on scintigrams divided by the tumor volume, as derived from CT, was determined twice within an interval of 2 weeks by observer 1 and once by observer 2 on day 1 of scintigraphy and once on day 2 of scintigraphy by observer 1.

RESULTS

The mean of the difference for the intra-, inter-, and day-to-day measurements were -3.4%, 2.4%, and -6%, respectively. No systematic bias was observed for the mean of the differences for the intra-, inter-, and day-to-day measurements. The respective confidence intervals for the mean of the differences of intra-, inter-, and day-to-day variability were -8.2%-1.4%, -2.9%-7.8%, and -14.7%-2.7%.

CONCLUSION

The reproducibility of quantitative 99mTc-HYNIC annexin-V tumor uptake measurements using a manual method appears to be acceptable for clinical use.

Apoptosis-detecting radioligands: current state of the art and future perspectives

This review provides a critical and thorough overview of the radiopharmaceutical development and in vivo evaluation of all apoptosis-detecting radioligands that have emerged so far, along with their possible applications in nuclear medicine. The following SPECT and PET radioligands are discussed: all forms of halogenated Annexin V (i.e. (123)I-labelled, (124)I-labelled, (125)I-labelled, (18)F-labelled), (99m)Tc/(94m)Tc-labelled Annexin V derivatives using different chelators and co-ligands (i.e. BTAP, Hynic, iminothiolane, MAG(3), EDDA, EC, tricarbonyl, SDH) or direct (99m)Tc-labelling, (99m)Tc-labelled Annexin V mutants and (99m)Tc/(18)F-radiopeptide constructs (i.e. AFIM molecules), (111)In-DTPA-PEG-Annexin V, (11)C-Annexin V and (64)Cu-, (67)Ga- and (68)Ga-DOTA-Annexin V. In addition, the potential role and clinical relevance of anti-PS monoclonal antibodies and other alternative apoptosis markers are reviewed, including: anti-Annexin V monoclonal antibodies, radiolabelled caspase inhibitors and substrates and mitochondrial membrane permeability targeting radioligands. Nevertheless, major emphasis is placed on the group of Annexin V-based radioligands, in particular (99m)Tc-Hynic-Annexin V, since this molecule is by far the most extensively investigated and best-characterised apoptosis marker at present. Furthermore, the newly emerging imaging modalities for in vivo detection of programmed cell death, such as MRI, MRS, optical, bioluminescent and ultrasound imaging, are briefly described. Finally, some future perspectives are presented with the aim of promoting the development of potential new strategies in pursuit of the ideal cell death-detecting radioligand.

Multidisciplinary approaches in the management of advanced head and neck tumors: state of the art

PURPOSE OF REVIEW

Head and neck cancer remains a significant cause of morbidity worldwide, with approximately 400,000 new cases per year. Ongoing advances in multidisciplinary management of this complex and multivaried disease process are resulting in improved function, quality of life, and survival. This review presents selected advances in primary research in head and neck cancer during the year 2003.

RECENT FINDINGS

Successful management of head and neck cancer now requires a cooperative approach among a broad group of medical disciplines that includes head and neck surgery, radiation oncology, medical oncology, medical imaging, clinical pathology and lab medicine, social work, nutrition, and others. Translation of continued advances in these fields by cooperative work will continue to yield incremental advances in diagnosis, staging, treatment, follow-up, supportive care, and quality of life. Accordingly, this review aims to include facets of each individual field. Diagnosis and staging continue to evolve with the inclusion of nuclear medicine and in vivo molecular imaging based on the technology of positron emission tomography and single photon emission computed tomographic scanning. Multimodality approaches remain the forefront of intervention for patients with advanced disease. Facets that continue to be defined and studied include the best treatment order of the three disciplines of surgery, radiation, and chemotherapy; the refinement of radiation by altering fraction dose, sequence, and time course; radiosensitization by chemo- and biologic therapy; and the addition of novel, biologically targeted agents to these disciplines. Following from the side effects of these intensive treatments to a functionally critical part of the body are ongoing advances in supportive care and quality of life.

SUMMARY

Head and neck cancer represents a collection of diseases that, although seemingly united by location and histology, on closer inspection represent a diverse collection of subcategories that often differ in pathogenesis, tumor biology, sublocation within the head and neck region, diagnosis, prognosis, treatment, and effect on quality of life. Given this complexity, it is not surprising that clinical management is also complicated and requires a cooperative effort among multiple subspecialties. This review of the current standard of care for patients with head and neck cancer aims to assist this diverse group of practitioners in caring for this complex group of patients.

The imaging of apoptosis with the radiolabeled annexin V: optimal timing for clinical feasibility

In recent years, the imaging of drug-induced apoptosis has become one of the centers of interest in experimental and clinical research. In particular, the accurate monitoring of chemosensitivity as well as the early prediction of chemoresistance in response to various pro-apoptotic interventions are critical requirements for the best management of oncology patients. The use of technetium [(99m)Tc]-labeled annexin V on animal and human models of cancers provides a proof of principle for the feasibility of a non-invasive, in vivo detection of an apoptotic signal and then for the early assessment of tumor response in the course of chemotherapy. Although promising, however, the initial clinical data point out on the technical limitations that are still to be resolved in terms of tumor-to-background ratio and optimal timing for the imaging of apoptosis. In the present review article, we report the results of animal studies aimed to the evaluation of apoptotic peaks following chemotherapy. In the light of these basic research works, we analyze the profiles of radiolabeled annexin V uptake over time as observed in clinical trials. We then discuss possible new imaging strategies designed to optimize the visualization of apoptotic changes within tumor tissues using the [(99m)Tc]-labeled annexin V. We also suggest longer lived forms of radiolabeled annexin V designed to better understand the temporal patterns of apoptotic tumor response, which in turn, may help to capture the best time-window for the imaging of cell death.

The ApoCorrect assay: a novel, rapid method to determine the biological functionality of radiolabeled and fluorescent Annexin A5

We have demonstrated that imaging of programmed cell death (PCD) in patients is possible using 99mTc-Annexin A5. Because of the short half-life of the technetium label it is important to limit the time span between the preparation of 99mTc-Annexin A5 and its administration into the patient. Therefore methods of quality control that determine the biological active fraction in the 99mTc-Annexin A5 should be not only accurate and precise but also rapid. We report the development and validation of a rapid, simple assay measuring the biological active fraction of 99mTc-Annexin A5. The assay is based on a solid phase of paramagnetic beads which are coated with phospholipids. Annexin A5 binds to these beads with high affinity if phosphatidyl serine is present within the phospholipid coat. Furthermore the binding depends on Ca2+ ions and functional Ca2+/phospholipid binding sites of Annexin A5. The bead assay is specific, stability-indicating, repeatable, and reproducible. It allows one to determine within 25 min the biological active fraction of a 99mTc-Annexin A5 preparation. We dubbed this assay the ApoCorrect assay.

Radiolabeled Annexin-V for Monitoring Treatment Response in Oncology

Because of its potential to allow for noninvasive, repetitive, and selective in vivo identification of the site and extent of apoptotic cell death and for monitoring cell death kinetics without the need for invasive biopsy, radiolabeled annexin-V is of major clinical relevance. This paper reviews available preclinical and clinical data on radiolabeled annexin-V pertaining to the domain of monitoring response to radiotherapy and chemotherapy, focusing especially on advantages and drawbacks of the different labeling procedures for the radiolabeling of annexin-V.

Relationship of 99mTc-HYNIC annexin V uptake to microvessel density, FasL and MMP-9 expression, and the number of tumour-infiltrating lymphocytes in head and neck carcinoma

This study reports on the relationship between quantitative (99m)Tc-HYNIC radiolabelled annexin V tumour uptake measurements, Fas ligand (FasL) expression, matrix metalloproteinase-9 (MMP-9) expression, microvessel density (MVD) and the number of tumour-infiltrating lymphocytes in squamous cell carcinoma of the head and neck (SCCHN) patients. Twenty-eight patients (24 men and 4 women; mean age 59 years, range 43-83 years) suffering from a primary ( n, number of patients=22) or locally recurrent ( n=6) SCCHN were studied. All patients underwent a spiral CT scan, allowing estimation of lesion size in three dimensions, and (99m)Tc-HYNIC annexin V scintigraphy within 1 week of each other. Biopsies or resection of the suspected primary tumour or local recurrence for histopathological analysis were performed on all patients within a period of 10 days following (99m)Tc-HYNIC annexin V scintigraphy. The percentage uptake of the injected dose of (99m)Tc-HYNIC annexin V in visible tumour lesions on scintigrams divided by the tumour volume, derived from CT, was related to MVD and to histological score (HSCORE) values for MMP-9 and FasL expression as well as to the number of tumour-infiltrating lymphocytes (CD45 staining). Median percentage absolute tumour uptake of the injected dose/cm(3) tumour volume derived from tomographic images was 0.0001% (SD 0.0001%) at 5-6 h p.i. (range: 0.000007-0.0003%). Mean HSCORE for MMP-9 tumour staining was 2.1 (SD 0.84). Mean HSCORE for FasL tumour staining was 2.49 (SD 0.92). At the sites of tumour containing the highest number of vessels, the mean MVD was 20 vessels/field at the hot spot (range 1-73). The median number of tumour-infiltrating lymphocytes was 500 (range 100-5,000). The percentage absolute tumour uptake of the injected dose/cm(3) tumour volume derived from tomographic images correlated linearly with FasL HSCORES( r=0.47, P=0.02). No correlation was found between the percentage absolute tumour uptake of the injected dose/cm(3) tumour volume derived from tomographic images and MMP-9 HSCORES, MVD or the number of tumour-infiltrating lymphocytes. MVD correlated significantly with MMP-9 HSCORES ( r=0.44, P=0.03).