Technetium-99m methoxyisobutylisonitrile chest imaging of small cell lung carcinoma: relation to patient prognosis and chemotherapy response--a preliminary report

⁹⁹mTc-N4amG: synthesis biodistribution and imaging in breast tumor-bearing rodents

(99m)Tc-N4-guanine ((99m)Tc-N4amG) was synthesized and evaluated in this study. Cellular uptake and cellular fraction studies were performed to evaluate the cell penetrating ability. Biodistribution and planar imaging were conducted in breast tumor-bearing rats. Up to 17%ID uptake was observed in cellular uptake study with 40% of (99m)Tc-N4amG was accumulated in the nucleus. Biodistribution and scintigraphic imaging studies showed increased tumor/muscle count density ratios as a function of time. Our results demonstrate the feasibility of using (99m)Tc-N4amG in tumor specific imaging.

Development of (99m)Tc-N4-NIM for molecular imaging of tumor hypoxia

The nitro group of 2-nitroimidazole (NIM) enters the tumor cells and is bioreductively activated and fixed in the hypoxia cells. 1,4,8,11-tetraazacyclotetradecane (N4) has shown to be a stable chelator for ^99mTc. The present study was aimed to develop ^99mTc-cyclam-2-nitroimidazole (^99mTc-N4-NIM) for tumor hypoxia imaging. N4-NIM precursor was synthesized by reacting N4-oxalate and 1,3-dibromopropane-NIM, yielded 14% (total synthesis). Cell uptake of ^99mTc-N4-NIM and ^99mTc-N4 was obtained in 13762 rat mammary tumor cells and mesothelioma cells in 6-well plates. Tissue distribution of ^99mTc-N4-NIM was evaluated in breast-tumor-bearing rats at 0.5–4 hrs. Tumor oxygen tension was measured using an oxygen probe. Planar imaging was performed in the tumor-bearing rat and rabbit models. Radiochemical purity of ^99mTc-N4-NIM was >96% by HPLC. Cell uptake of ^99mTc-N4-NIM was higher than ^99mTc-N4 in both cell lines. Biodistribution of ^99mTc-N4-NIM showed increased tumor-to-blood and tumor-to-muscle count density ratios as a function of time. Oxygen tension in tumor tissue was 6–10 mmHg compared to 40–50 mmHg in normal muscle tissue. Planar imaging studies confirmed that the tumors could be visualized clearly with ^99mTc-N4-NIM in animal models. Efficient synthesis of N4-NIM was achieved. ^99mTc-N4-NIM is a novel hypoxic probe and may be useful in evaluating cancer therapy.

Synthesis and evaluation of amino acid-based radiotracer 99mTc-N4-AMT for breast cancer imaging

Purpose. This study was to develop an efficient synthesis of ^99mTc-O-[3-(1,4,8,11-tetraazabicyclohexadecane)-propyl]-α-methyl tyrosine (^99mTc-N4-AMT) and evaluate its potential in cancer imaging. Methods. N4-AMT was synthesized by reacting N4-oxalate and 3-bromopropyl AMT (N-BOC, ethyl ester). In vitro cellular uptake kinetics of ^99mTc-N4-AMT was assessed in rat mammary tumor cells. Tissue distribution of the radiotracer was determined in normal rats at 0.5–4 h, while planar imaging was performed in mammary tumor-bearing rats at 30–120 min. Results. The total synthesis yield of N4-AMT was 14%. Cellular uptake of ^99mTc-N4-AMT was significantly higher than that of ^99mTc-N4. Planar imaging revealed that ^99mTc-N4-AMT rendered greater tumor/muscle ratios than ^99mTc-N4. Conclusions. N4-AMT could be synthesized with a considerably high yield. Our in vitro and in vivo data suggest that ^99mTc-N4-AMT, a novel amino acid-based radiotracer, efficiently enters breast cancer cells, effectively distinguishes mammary tumors from normal tissues, and thus holds the promise for breast cancer imaging.

Predicting early chemotherapy response with technetium-99m methoxyisobutylisonitrile SPECT/CT in advanced non-small cell lung cancer

PURPOSE

The purpose of this study is to examine the prognostic value of prechemotherapy technetium-99m methoxyisobutylisonitrile ((99m)Tc-MIBI) uptake with single photon emission computed tomography/computed tomography (SPECT/CT) in relation to tumor size change measured by CT.

METHODS

Eleven patients with stage IIIB/IV non-small cell lung cancer (NSCLC) underwent (99m)Tc-MIBI SPECT/CT within 24 h before starting platinum-containing chemotherapy. Following the Response Evaluation Criteria in Solid Tumors guidelines, 20 lesions from the 11 patients were available for evaluation. Maximum (C (max)) and mean (C (mean)) MIBI counts were calculated for each lesion. One-dimensional (1D; longest diameter) and two-dimensional (2D; area of the largest transverse surface) tumor measurements were assessed by two observers on the diagnostic CT and the response assessment CT after two cycles of chemotherapy.

RESULTS

Bland-Altman analysis demonstrated no clinically significant bias between the observers. A solid correlation was found between (99m)Tc-MIBI C (mean) and change in the longest diameter (1D change) of the target lesion (rho = -0.62) using Spearman's rank correlation test. C (mean) also correlated negatively with change in the area of the largest transverse surface (2D change) of the target lesion (rho = -0.53). Furthermore, a correlation was established between (99m)Tc-MIBI C (max) and 1D change (rho = -0.56) in tumor size as well, though less strongly when compared to its C (mean) counterpart.

CONCLUSIONS

Our series demonstrated solid, negative correlations between prechemotherapy (99m)Tc-MIBI uptake and tumor size change measured by CT for advanced NSCLC, particularly with C (mean) and 1D change.

Neoadjuvant therapy in locally advanced breast cancer: 99mTc-MIBI mammoscintigraphy is not a reliable technique to predict therapy response

Mammoscintigraphy (MMS) has been indicated as a useful tool in predicting response to therapy in cancer. However, contrasting results have been reported in the literature for breast cancer patients. The aim of this study was to explore the role of MMS in locally advanced breast cancer (LABC) patients. Fifty-one patients affected by LABC and scheduled for neoadjuvant therapy were enrolled. Breast tumor status was evaluated at baseline, during therapy and at the completion of therapy by radiological techniques and by MMS. Pre-therapy (MMS1) and post-therapy MIBI (2-methoxyisobutilysonitrile) images (MMS2-3) were analyzed. MMS1 was performed in all pts, 41 carried out MMS2 and 27 had MMS3. Tumor uptake and washout in MMS1 did not show any correlation with the therapy response. The absence of any association between tumor uptake and washout with respect to therapy response suggests that MMS is not a reliable technique to predict therapy response in LABC.

[Expression of multidrug resistance (MDR)-associated proteins in solid tumors]

The causes of drug resistance in tumor cells vary widely. The present study aims to provide an update of multidrug resistance in tumor cells and, in particular, of multidrug resistance-associated proteins.

Tc-99m MIBI SPECT in prediction of prognosis in patients with small cell lung cancer

PURPOSE

The purpose of this study was to evaluate whether the degree of technetium-99m methoxyisobutylisonitrile (MIBI) uptake and its retention in delayed imaging in small cell lung cancer (SCLC) was correlated with the response to multiagent chemotherapy and to investigate if there was a relationship between the survival time of patients with SCLC and Tc-99m MIBI SPECT tumor uptake parameters at the time of diagnosis.

METHODS

Between 1998 and by December 2004, 40 patients with SCLC were studied with Tc-99m MIBI SPECT at the time of diagnosis. The patients were classified by a follow-up CT as good responders (complete or partial remission) and poor responders (stable disease or progressive disease). Following i.v. administration of 740 MBq Tc-99m MIBI, SPECT imaging at 30 minutes (early) and 2 hours (delayed) was performed. Regions of interests were placed over the tumors and contralateral normal lung tissue on one transverse section. The uptake ratio of the lesion to that in the contralateral normal lung was obtained from early images (early ratio; ER) as well as delayed images (delayed ratio; DR). The retention index (RI%) was measured as: RI% = [(DR-ER)/ER] x 100. Tc-99m MIBI tumor uptake parameters were compared with chemotherapeutic response and survival time.

RESULTS

Of 40 patients, 29 patients were good responders (72.5%) and 11 patients were poor responders (27.5%). RI% of Tc-99m MIBI SPECT in the group of good response was significantly higher than in that with poor response (p < 0.05). On the other hand, there was no significant difference between the two groups with respect to ER or DR values. Four of 40 patients were still alive with disease (10%). The patient survival time varied from 1 to 70 months (mean survival time = 12.9 +/- 13.4 months). There was no significant difference between the survival time of patients with respect to ER or DR of Tc-99m MIBI SPECT imaging. When median RI% was accepted as a cut-off value (-3.85%), patients with higher RI% values had a longer survival time (12 months) when compared with those with low RI% (8 months), p < 0.05.

CONCLUSION

Our results suggest that Tc-99m MIBI SPECT could accurately predict the chemotherapy response in patients with SCLC. RI% of Tc-99m MIBI SPECT is recommended to differentiate patients with a poor response to chemotherapy and good responders, and RI% of Tc-99m MIBI SPECT appears as the only parameter that may be useful in predicting the survival of patients with SCLC.

Targeted molecular imaging in oncology

Improvement of scintigraphic tumor imaging is extensively determined by the development of more tumor specific radiopharmaceuticals. Thus, to improve the differential diagnosis, prognosis, planning and monitoring of cancer treatment, several functional pharmaceuticals have been developed. Application of molecular targets for cancer imaging, therapy and prevention using generator-produced isotopes is the major focus of ongoing research projects. Radionuclide imaging modalities (positron emission tomography, PET; single photon emission computed tomography, SPECT) are diagnostic cross-sectional imaging techniques that map the location and concentration of radionuclide-labeled radiotracers. 99mTc- and 68Ga-labeled agents using ethylenedicysteine (EC) as a chelator were synthesized and their potential uses to assess tumor targets were evaluated. 99mTc (t1/2 = 6 hr, 140 keV) is used for SPECT and 68Ga (t1/2 = 68 min, 511 keV) for PET. Molecular targets labeled with Tc-99m and Ga-68 can be utilized for prediction of therapeutic response, monitoring tumor response to treatment and differential diagnosis. Molecular targets for oncological research in (1) cell apoptosis, (2) gene and nucleic acid-based approach, (3) angiogenesis (4) tumor hypoxia, and (5) metabolic imaging are discussed. Numerous imaging ligands in these categories have been developed and evaluated in animals and humans. Molecular targets were imaged and their potential to redirect optimal cancer diagnosis and therapeutics were demonstrated.

To use MIBI or not to use MIBI? That is the question when assessing tumour cells

99mTc-sestamibi (MIBI) is a well-known tumour imaging agent. Its retention within tumour cell mitochondria is related to perfusion and to the magnitude of the electrical gradient, reflecting cell viability. Several internal cell factors modulate this uptake; for example, multidrug resistance membrane proteins (Pgp and MRP1) and anti-apoptotic BCl-2 protein of the outer mitochondrial membrane can limit retention of MIBI. At the early stage of cell apoptosis, the electrical driving forces of MIBI uptake are impaired, and influx and accumulation are reduced. It seems clear that MIBI can be used before treatment to detect drug resistance, assess anti-apoptotic status and predict treatment efficacy. Although it has been suggested that MIBI might be used to monitor tumour response to treatment, MIBI is unable to differentiate tumours with ongoing apoptosis from those developing drug resistance.

Residual tumor uptake of [99mTc]-sestamibi after neoadjuvant chemotherapy for locally advanced breast carcinoma predicts survival

BACKGROUND

Studies utilizing serial [99mTc]-sestamibi (MIBI) scintimammography have reported accurate prediction of tumor response in patients with locally advanced breast carcinoma (LABC) undergoing neoadjuvant chemotherapy. The pathologic response of LABC to presurgical treatment regimens is a prognostic indicator of survival. The authors tested whether MIBI uptake posttherapy predicted survival.

METHODS

Sixty-two patients with LABC underwent MIBI scintimammography just before chemotherapy and 2 months after treatment initiation. An additional MIBI scan was performed if treatment lasted >3 months. The affected breast was imaged within 10 minutes after injection to reflect early uptake, which the authors have shown to be related to tumor blood flow. MIBI uptake was quantified using the lesion-to-normal breast (L:N) ratio. Most patients (93%) received weekly dose-intensive doxorubicin-based treatment. Disease-free survival (DFS) and overall survival (OS) were compared with posttherapy primary MIBI uptake and with other established prognostic factors for neoadjuvantly treated LABC, namely, primary tumor pathologic response and posttherapy axillary lymph node status.

RESULTS

Patients with high uptake on the last observed MIBI scan (i.e., the L:N ratio was greater than the median value) had poorer DFS and OS (P<0.01 and P=0.01, respectively). Residual MIBI uptake retained independent prognostic significance in preliminary multivariate analysis that included other established prognostic markers.

CONCLUSIONS

High primary breast tumor MIBI uptake after neoadjuvant chemotherapy predicted poor survival, suggesting serial MIBI imaging may provide a useful quantitative surrogate end point for neoadjuvant chemotherapy trials. Given the association between MIBI uptake and tumor blood flow, this prognostic capability may be related to retained tumor vascularity after treatment.

Optimization of technetium-99m Sestamibi single-photon emission tomography to define multidrug resistance with confidence

BACKGROUND

The efflux rate of technetium-99m Sestamibi (99mTc-Sestamibi) is a kinetic phenomenon related to the response of cancer cells to chemotherapy, and may be used to determine drug resistance. Measurement of the efflux rate requires accurate quantitative single-photon emission tomography (SPET) imaging within the time constraints imposed by the kinetics of the process.

METHODS

A phantom study, at activity concentrations typically found with 99mTc-Sestamibi in vivo, was undertaken to optimize the SPET parameters and, in particular, to determine whether 180 degrees acquisition arcs with heads in 'L' configuration could be used for accurate quantification. Following the development of the most appropriate SPET protocol, a small patient pilot study was undertaken.

RESULTS

Studies designed to evaluate statistical uncertainty (noise), contrast restitution and spatial resolution of the data sets, using different acquisition and reconstruction parameters, showed that 180 degrees SPET using a 64 x 64 matrix, 6 degrees angular sampling and iterative reconstruction was optimal. Finer linear and/or angular sampling afforded negligible improvement in resolution, but markedly increased the statistical uncertainty. Comparison of 360 degrees and 180 degrees acquisitions, utilizing conventional filtered backprojection and iterative reconstruction algorithms, demonstrated that the statistical uncertainty was reduced to a greater extent for 180 degrees data collection. For 360 degrees (64 x 64) data acquisition, statistical uncertainty decreased from 15% to 11% using the iterative algorithm, whilst the 180 degrees (64 x 64) data showed a reduction from 20% to 7%, and approached values obtained by planar imaging. The efflux measurements obtained in the patient pilot study were consistent with the observed chemotherapy response.

CONCLUSION

Our study shows that 180 degrees acquisition arcs are a practical option for accurate quantitative SPET kinetic imaging for potential studies of chemotherapy response in patients with lung cancer.

Assessment of Therapeutic Tumor Response Using 99mTc-Ethylenedicysteine-Glucosamine

PURPOSE

The aim of this study was to evaluate 99mTc-ethylenedicysteine-glucosamine (EC-DG) for the assessment of tumor growth.

METHOD

To evaluate whether 99mTc-EC-DG is involved in cell nuclei activity, in vitro thymidine incorporation, and cell-cycle assays of EC-DG were conducted using lung and breast cancer cells. Biodistribution of 99mTc-EC-DG in lung tumor-bearing mice (0.5-4 hours, 1 Ci/mouse, i. v.) was used to estimate the radiation-absorbed dose. Autoradiograms of 99mTc-EC-DG and 18F-FDG were compared in nude mice bearing uterine sarcoma. Rabbits inoculated with VX-2 cells were imaged with 99mTc-EC-DG and 99mTc-EC. For therapeutic assessment studies, scintigraphic imaging studies with 99mTc-EC-DG in mammary tumor-bearing rats were conducted at various days after treatment with paclitaxel and cisplatin. The imaging findings were correlated immunohistochemical assays (mRNA expression, apoptosis, and cell-cycle changes in tumor), and flow cytometry analysis was performed.

RESULTS

In vitro cellular uptake assays indicated that cell nuclei activity could be assessed by 99mTc-EC-DG. Scintigraphy and autoradiograms in animal models demonstrated that the tumor could be clearly visualized by 99mTc-EC-DG. The efficacy of paclitaxel and cisplatin treatment in rodent models could be assessed using tumor/muscle ratios. Immunohistochemical staining indicated a reduced expression of bFGF and an increased apoptosis and cell-cycle changes after paclitaxel and cisplatin treatment.

CONCLUSION

99mTc-EC-DG is involved in cell nuclei activity and could assess the therapeutic tumor response.

Monitoring mitochondrial metabolisms in irradiated human cancer cells with 99mTc-MIBI

Cationic hexakis(2-methoxyisobutylisonitrile)-technetium-99m ((99m)Tc-MIBI), an agent for scintigraphic detection and imaging of tumors, accumulates in mitochondria of various cells and tissues of high mitochondrial metabolic activity. To monitor the mitochondrial metabolisms of human cancer cells exposed to ionizing radiation, uptake of (99m)Tc-MIBI in an irradiated human lung cancer cell line (A549) was measured at 1-12 h following 0-9 Gy irradiation in vitro. Mitochondrial membrane potential, an index of mitochondrial activity, was also determined by flow cytometry with 3,3'-dihexyloxacarbocyanine (DiOC6(3)). At 1 h after 3 and 9 Gy irradiation, cellular (99m)Tc-MIBI accumulation increased by 10.5 +/- 1.6 and 16.8 +/- 5.6% compared with controls, respectively (P < 0.01) DiOC6(3) measurement also showed increased mitochondrial membrane potentials immediately after irradiation, consistent with (99m)Tc-MIBI changes. The present findings showed that the transient hyperactivated mitochondrial metabolism and subsequently decreased activities following irradiation were monitored by determining the cellular (99m)Tc-MIBI accumulation, suggesting the possibility of (99m)Tc-MIBI scintigraphy as a functional imaging to monitor tumor metabolisms after radiation therapy.

Imaging with 99mTc ECDG targeted at the multifunctional glucose transport system: feasibility study with rodents

PURPOSE

To evaluate the feasibility of technetium 99m ((99m)Tc) ethylenedicysteine-deoxyglucose (ECDG) imaging in tumor-bearing rodents.

MATERIALS AND METHODS

ECDG was synthesized by means of reacting ethylenedicysteine with glucosamine, with carbodiimide as the coupling agent. Hexokinase assays were performed at an ultraviolet wavelength of 340 nm. To determine whether blood glucose level could be altered, ECDG or glucosamine was injected into six rats. In a separate study, ECDG followed by insulin was administered to three rats. To determine biodistribution, lung tumor cells were intramuscularly injected into the hind legs of 18 nude mice. The animals were then injected with (99m)Tc ECDG or fluorine 18 ((18)F) fluorodeoxyglucose (FDG) (0.037-0.074 MBq per mouse). Radioactivity was measured in tissue excised from the animals. Scintigraphy was performed in three groups: in group 1 to demonstrate that different-sized tumors could be imaged after (99m)Tc ECDG administration, in group 2 to ascertain whether tumor uptake of (99m)Tc ECDG was perfusion related, and in group 3 to demonstrate that tumor uptake of (99m)Tc ECDG occurred by means of a glucose-mediated process.

RESULTS

ECDG was positive for phosphorylation at hexokinase assay. Blood glucose level increased with ECDG injection and decreased with insulin administration. Tumor-to-brain tissue and tumor-to-muscle tissue ratios of (99m)Tc ECDG uptake were higher than those of (18)F FDG uptake. Scintigraphic results demonstrated the feasibility of (99m)Tc ECDG imaging.

CONCLUSION

There are similarities between (99m)Tc ECDG uptake and (18)F FDG uptake in tumors, and study findings supported the potential use of (99m)Tc ECDG as a functional imaging agent.

Assessment of antiangiogenic effect using 99mTc-EC-endostatin

PURPOSE

Tumor vascular density may provide a prognostic indicator of metastatic potential or survival. The purpose of this study was to develop 99mTc-ethylenedicysteine-endostatin (99mTc-EC-endostatin) for the evaluation of anti-angiogenesis therapy.

METHOD

99mTc-EC-endostatin was prepared by conjugating ethylenedicysteine (EC) to endostatin, followed by adding pertechnetate and tin chloride. Radiochemical purity was > 95%. In vitro cell viability, affinity and TUNEL assays were performed. Tissue distribution and planar imaging of radiolabeled endostatin were determined in tumor-bearing rats. To assess anti-angiogenic treatment response, rats were treated with endostatin, paclitaxel and saline, followed by imaging with 99mTc-EC-endostatin. Tumor response to endostatin therapy in tumor-bearing animal models was assessed by correlating tumor uptake dose with microvessel density, VEGF, bFGF and IL-8 expression during endostatin therapy.

RESULTS

In vitro cell viability and TUNEL assays indicated no marked difference between EC-endostatin and endostatin. Cellular uptake assay suggests that endostatin binds to endostatin receptor. Biodistribution of 99mTc-EC-endostatin in tumor-bearing rats showed increased tumor-to-tissue count density ratios as a function of time. Tumor uptake (%ID/g) of 99mTc-EC-endostatin was 0.2-0.5. Planar images confirmed that the tumors could be visualized clearly with 99mTc-EC-endostatin. The optimal time for imaging using radiolabeled endostatin was 2 hrs. 99mTc-EC-endostatin could assess treatment response. There was a correlation between tumor uptake and cellular targets expression.

CONCLUSION

The results indicate that it is feasible to use 99mTc-EC-endostatin to assess efficiency of anti-angiogenesis therapy.

Focal pulmonary uptake during Tc-99m myocardial perfusion SPECT imaging

PURPOSE

To evaluate the incidence and origin of abnormal focal pulmonary uptake during myocardial perfusion SPECT imaging (MSPECT).

METHODS

For evaluation of chest pain, 790 men and 581 women (mean age, 56 +/- 13 years) underwent MSPECT. All of them received adenosine for pharmacologic stress and Tc-99m tetrofosmin (TF, n = 817) or Tc-99m sestamibi (MIBI, n = 554) for myocardial perfusion imaging.

RESULTS

Review of chest radiography with or without computed tomography revealed 111 (8.1%) focal pulmonary diseases. Among them, 38 (34.2%) showed focal pulmonary uptake (TF, 22; MIBI, 16); 27 (30.7%) of 88 showed previous pulmonary tuberculosis; 2 of 10 (20%) benign pulmonary nodules; 4 of 5 (80%) metastatic lung cancers; 2 of 4 (50%) primary lung cancers; and 3 of 4 (75%) pneumonias. No difference in uptake was noted for the two imaging agents. Intensity of uptake did not vary with origin of the uptake. Focal abnormal pulmonary uptake was found in 2.8% of patients undergoing MSPECT and in 34.2% of patients in whom radiological examinations showed regional pulmonary disease. In patients with abnormal pulmonary uptake on MSPECT, 16% had a malignant lesion, whereas 75% of patients with a pulmonary nodule shown on radiography and focal pulmonary uptake on MSPECT had a malignant lesion.

CONCLUSIONS

Although the incidence of abnormal pulmonary uptake during MSPECT was very low, the incidence of malignant lesions in the patients with nodular pulmonary uptake was relatively high.

Technetium-99m methoxyisobutylisonitrile chest imaging for small-cell lung cancer. Relationship to chemotherapy response (six courses of combination of cisplatin and etoposide) and p-glycoprotein or multidrug resistance related protein expression

AIMS

This is a retrospective and adaptive randomization study. The purpose of this study was to evaluate the relationship between technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) chest-imaging results, chemotherapy response and P-glycoprotein (Pgp) or multidrug resistance related protein (MRP) expression in small-cell lung cancer (SCLC).

PATIENTS AND METHODS

Before chemotherapy, 30 patients (11 females, 19 males, ages: 52-69 years) with SCLC, including 14 extensive diseases without localized problems and 16 limited diseases in excess of solitary pulmonary nodule, underwent early chest imaging, including visual interpretation and quantitative analyses of tumor uptake ratio (TUR), 10 minutes after intravenous injection of Tc-99m MIBI. Immunohistochemical analyses were performed, using multiple nonconsecutive sections of the biopsy specimens, to detect Pgp and MRP expressions. Chemotherapy response was evaluated in the third month after completion of treatment by clinical and radiological methods.

RESULTS

All 15 (100%) of the SCLC patients with complete or partial response had positive Tc-99m MIBI chest SPECT results, but negative ones for both Pgp and MRP expression. Twelve of the 15 (80%) SCLC patients with no response or progressive disease had negative Tc-99m MIBI chest SPECT results and were positive for either Pgp or MRP expression (P < 0.05). Negative Tc-99m MIBI chest SPECT results predicted complete or partial response. The TUR of patients with complete or partial response (1.91 +/- 0.29 with a 95% confidence interval (95% CI): 1.75-2.07) was significantly higher than that of patients with no response or progressive disease (1.19 +/- 0.28 with a 95% CI: 1.04-1.35).

CONCLUSION

Tc-99m MIBI chest images are a potential tool for understanding Pgp and MRP expressions in SCLC and for predicting patient chemotherapy response.

Evaluation of chemotherapy response using technetium-99M-sestamibi scintigraphy in untreated adult malignant lymphomas and comparison with other prognosis factors: a preliminary report

The purpose of this study was to predict chemotherapy response using technetium-99m methoxyisobutylisonitrile (Tc-MIBI) scintigraphy in untreated adult malignant lymphomas (ML) and compare the response with other prognosis factors. Before chemotherapy, 25 adult patients with ML were enrolled in this study. Tc-MIBI scintigraphy was performed 10 min after intravenous injection of Tc-MIBI to calculate tumor-to-background (T/B) uptake ratio and interpret the results visually. Chemotherapy response was evaluated in the first 1 to 2 years after completion of treatment by clinical and radiological methods. The mean T/B uptake ratio of the 15 patients with good response (3.3 +/- 0.6) was significantly higher than that of the 10 patients with poor response (1.2 +/- 0.1). All of the 15 patients with good response had positive Tc-MIBI scintigraphic results. All of the 10 patients with poor response had negative Tc-MIBI scintigraphic results. However, there were no significant differences in the incidences of good and poor responses for other prognosis factors. In our preliminary study, when compared with other prognosis factors, Tc-MIBI scintigraphy was the best tool to predict chemotherapy response in adult patients with ML.

Prediction of chemotherapeutic response by Technetium 99m--MIBI scintigraphy in breast carcinoma patients

BACKGROUND

Significance of Technetium 99m ((99m)Tc)-MIBI scintigraphy in the prediction of response to anthracylines and taxanes (both are substrates for P-glycoprotein [P-gp]) as well as relation between (99m)Tc-MIBI uptake and P-gp or MDR1 mRNA expression in tumors were studied in patients with breast carcinoma.

METHODS

Forty-six female patients with locally advanced (n = 15) or metastatic (n = 31) breast carcinoma were recruited in this study. Before chemotherapy (epirubicin and cyclophosphamide [n = 20] or decetaxel [n = 26]), (99m)Tc-MIBI scintigraphy was performed to obtain the T/N (tumor to normal tissue) ratios of (99m)Tc-MIBI uptake at 10 minutes (T/N[e]) and at 180 minutes (T/N[d]) after the (99m)Tc-MIBI injection. Expression of MDR1 mRNA and P-gp in tumors (n = 32) were determined by a quantitative real-time polymerase chain reaction and immunohistochemistry, respectively.

RESULTS

Clinical significance of T/N(e) and T/N(d) ratios in the prediction of chemotherapeutic response was evaluated using the arbitrary cutoff values of 3.0 for T/N(e) ratios and 2.0 for T/N(d) ratios. Positive predictive value, negative predictive value, and diagnostic accuracy of T/N(d) ratios (81.0%, 96.0%, and 89.1%, respectively) were higher, although statistically not significant, than those of T/N(e) ratios (73.3%, 77.4%, and 76.1%, respectively), and these values were not affected by type of chemotherapy. MDR1 mRNA levels were not significantly different between the lesions with high (> or = 2.0) and low (< 2.0) T/N(d) ratios, but P-gp expression was significantly (P < 0.01) higher in the lesions with low T/N(d) ratios than in those with high T/N(d) ratios.

CONCLUSIONS

T/N(d) ratios determined by (99m)Tc-MIBI scintigraphy are useful in the prediction of response to chemotherapy with epirubicin and cyclophosphamide or docetaxel as well as in the in vivo evaluation of P-gp expression status in tumors in patients with locally advanced or recurrent breast carcinoma.

Phase I and pharmacokinetic study of the novel MDR1 and MRP1 inhibitor biricodar administered alone and in combination with doxorubicin

PURPOSE

To evaluate the safety, tolerability, and pharmacokinetics of biricodar (VX-710), an inhibitor of P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP1), alone and with doxorubicin in patients with advanced malignancies. The effect of VX-710 on the tissue distribution of (99m)Tc-sestamibi, a P-gp and MRP1 substrate, was also evaluated.

PATIENTS AND METHODS

Patients with solid malignancies refractory to standard therapy first received a 96-hour infusion of VX-710 alone at 20 to 160 mg/m(2)/h. After a 3-day washout, a second infusion of VX-710 was begun, on the second day of which doxorubicin 45 mg/m(2) was administered. Cycles were repeated every 21 to 28 days. (99m)Tc-sestamibi scans were performed before and during administration of VX-710 alone.

RESULTS

Of the 28 patients who enrolled, 25 patients were eligible for analysis. No dose-limiting toxicity (DLT) was observed in the nine assessable patients who received 120 mg/m(2)/h or less. Among seven patients receiving VX-710 160 mg/m(2)/h, two DLTs were seen: reversible CNS toxicity and febrile neutropenia. All other adverse events were mild to moderate and reversible. Plasma concentrations of VX-710 in patients who received at 120 and 160 mg/m(2)/h were two- to fourfold higher than concentrations required to fully reverse drug resistance in vitro. VX-710 exhibited linear pharmacokinetics with a harmonic mean half-life of 1.1 hours. VX-710 enhanced hepatic uptake and retention of (99m)Tc-sestamibi in all patients.

CONCLUSION

A 96-hour infusion of VX-710 at 120 mg/m(2)/h plus doxorubicin 45 mg/m(2) has acceptable toxicity in patients with refractory malignancies. The safety and pharmacokinetics of VX-710 plus doxorubicin warrant efficacy trials in malignancies expressing P-gp and/or MRP1.

Technetium-99m-sestamethoxyisobutylisonitrile scan as a predictor of chemotherapy response in malignant lymphomas compared with P-glycoprotein expression, multidrug resistance-related protein expression and other prognosis factors

The purpose of the present study was to predict the response of malignant lymphomas (MLs) to chemotherapy using technetium-99m methoxyisobutylisonitrile (Tc-MIBI) scan and to compare it with the predictive ability of P-glycoprotein (P-gp) expression, multidrug resistance-related protein (MRP) expression and other prognosis factors. Twenty-five ML patients were enrolled in this study prior to initiation of chemotherapy. Images were obtained 10 min after intravenous injection of Tc-MIBI, interpreted visually and the tumour-to-background (T/B) ratios calculated. Immunohistochemical analyses were performed on sections of the biopsy specimens to determine P-gp and MRP expression. Chemotherapy response was evaluated in the first 1-2 years after completion of chemotherapy. The mean T/B ratio of the 15 patients with a good response (3.3 +/- 0.6) was significantly higher than that of the 10 patients with a poor response (1.2 +/- 0.1). All 15 patients with a good chemotherapy response had positive Tc-MIBI scan results and negative P-gp and MRP expression. All 10 patients with a poor response had negative Tc-MIBI scan results and either positive P-gp or MRP expression. Other prognosis factors showed no significant difference in the incidence of good and poor responses. Tc-MIBI scan results represent P-gp or MRP expression more accurately than other prognosis factors and predict the chemotherapy response in ML patients.

In vivo and in vitro measurement of apoptosis in breast cancer cells using 99mTc-EC-annexin V

OBJECTIVE

The purpose of this study was to develop an imaging technique to measure and monitor tumor cells undergoing programmed death caused by radiation and chemotherapy using 99mTc-EC-annexin V. Annexin V has been used to measure programmed cell death both in vitro and in vivo. Assessment of apoptosis would be useful to evaluate the efficacy and mechanisms of therapy and disease progression or regression.

METHODS

Ethylenedicysteine (EC) was conjugated to annexin V using sulfo-N-hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide-HCl as coupling agents. The yield of EC-annexin V was 100%. In vitro cellular uptake, pre- and post-radiation (10-30 Gy) and paclitaxel treatment, was quantified using 99mTc-EC-annexin V. Tissue distribution and planar imaging of 99mTc-EC-annexin V were determined in breast tumor-bearing rats at 0.5, 2, and 4 hrs. To demonstrate in vivo cell apoptosis that occurred during chemotherapy, a group of rats was treated with paclitaxel and planar imaging studies were conducted at 0.5-4 hrs. Computer outlined region of interest (ROI) was used to quantify tumor uptake on day 3 and day 5 post-treatment.

RESULTS

In vitro cellular uptake showed that there was significantly increased uptake of 99mTc-EC-annexin V after irradiation (10-30 Gy) and paclitaxel treatment. In vivo biodistribution of 99mTc-EC-annexin in breast tumor-bearing rats showed increased tumor-to-blood, tumor-to-lung and tumor-to-muscle count density ratios as a function of time. Conversely, tumor-to-blood count density ratios showed a time-dependent decrease with 99mTc-EC in the same time period. Planar images confirmed that the tumors could be visualized clearly with 99mTc-EC-annexin. There was a significant difference of ROI ratios between pre- and post-paclitaxel treatment groups at 2 and 4 hrs post injection.

CONCLUSION

The results indicate that apoptosis can be quantified using 99mTc-EC-annexin and that it is feasible to use 99mTc-EC-annexin to image tumor apoptosis.

Technetium-99m MIBI single photon emission computed tomography as an indicator of prognosis for patients with lung cancer-preliminaly report

PURPOSE

We performed technetium-99m hexakis-2-methoxyisobutylisonitrile (Tc-99m MIBI) single photon emission computed tomography (SPECT) in 23 patients with primary lung cancer between July 1993 and March 1996. We evaluated the relationships among the uptake ratio, retention index and the prognosis after radiation therapy and/or chemotherapy.

MATERIALS AND METHODS

Tc-99m MIBI SPECT was performed at 30 minutes and at 3 hours after intravenous injection of 600 MBq of Tc-99m MIBI with three gamma camera detectors (GCA-9300A/HG) on transverse SPECT images. Regions of interest were set in the area of abnormal uptake of Tc-99m MIBI and in the contralateral normal lung. The ratio of uptake in the lesion to that in the contralateral normal lung was obtained on early images (early ratio; ER) as well as delayed images (delayed ratio: DR). The retention index (RI) was calculated as follows: RI = (DR - ER)/ER x 100. The ratio was compared with survival time and prognostic factors.

RESULTS

There was no correlation between ER and DR. The patients with high RI survived longer than those with low RI (median survival, 19.4 months vs. 9.4 months; p = 0.0104 by the Mantel-Cox test).

CONCLUSION

These results suggest that RI is the most useful among Tc-99m MIBI indices of primary lung cancer in predicting prognosis.

Assessment of resistance to paclitaxel of murine tumors by (99m)Tc-MIBI/(201)Tl dual-radionuclide imaging

This study investigated P-glycoprotein (Pgp) expression by murine tumors with and without resistance to paclitaxel and the role of (99m)Tc-2-methoxyisobutylisonitrile (MIBI)/(201)Tl imaging in predicting the effect of paclitaxel. Antitumor effect of paclitaxel and biodistribution of the radiopharmaceuticals were evaluated in mice bearing four tumor types. Pgp expression did not correlate with the antitumor efficacy of paclitaxel. Although the absolute uptake of (99m)Tc-MIBI did not correlate with Pgp expression, (99m)Tc-MIBI could predict paclitaxel sensitivity by its higher uptake.