Comparative study of Tc-99m MIBI and TI-201 SPECT in predicting chemotherapeutic response in non-small-cell lung cancer

Targeting MDR in breast and lung cancer: discriminating its potential importance from the failure of drug resistance reversal studies

This special issue of Drug Resistance Updates is dedicated to multidrug resistance protein 1 (MDR-1), 35 years after its discovery. While enormous progress has been made and our understanding of drug resistance has become more sophisticated and nuanced, after 35 years the role of MDR-1 in clinical oncology remains a work in progress. Despite clear in vitro evidence that P-glycoprotein (Pgp), encoded by MDR-1, is able to dramatically reduce drug concentrations in cultured cells, and that drug accumulation can be increased by small molecule inhibitors, clinical trials testing this paradigm have mostly failed. Some have argued that it is no longer worthy of study. However, repeated analyses have demonstrated MDR-1 expression in a tumor is a poor prognostic indicator leading some to conclude MDR-1 is a marker of a more aggressive phenotype, rather than a mechanism of drug resistance. In this review we will re-evaluate the MDR-1 story in light of our new understanding of molecular targeted therapy, using breast and lung cancer as examples. In the end we will reconcile the data available and the knowledge gained in support of a thesis that we understand far more than we realize, and that we can use this knowledge to improve future therapies.

A pharmacodynamic study of docetaxel in combination with the P-glycoprotein antagonist tariquidar (XR9576) in patients with lung, ovarian, and cervical cancer

PURPOSE

P-glycoprotein (Pgp) antagonists have been difficult to develop because of complex pharmacokinetic interactions and a failure to show meaningful results. Here we report the results of a pharmacokinetic and pharmacodynamic trial using a third-generation, potent, noncompetitive inhibitor of Pgp, tariquidar (XR9576), in combination with docetaxel.

EXPERIMENTAL DESIGN

In the first treatment cycle, the pharmacokinetics of docetaxel (40 mg/m(2)) were evaluated after day 1 and day 8 doses, which were administered with or without tariquidar (150 mg). (99m)Tc-sestamibi scanning and CD56(+) mononuclear cell rhodamine efflux assays were conducted to assess Pgp inhibition. In subsequent cycles, 75 mg/m(2) docetaxel was administered with 150 mg tariquidar every 3 weeks.

RESULTS

Forty-eight patients were enrolled onto the trial. Nonhematologic grade 3/4 toxicities in 235 cycles were minimal. Tariquidar inhibited Pgp-mediated rhodamine efflux from CD56(+) cells and reduced (99m)Tc-sestamibi clearance from the liver. There was striking variability in basal sestamibi uptake; a 12% to 24% increase in visible lesions was noted in 8 of 10 patients with lung cancer. No significant difference in docetaxel disposition was observed in pairwise comparison with and without tariquidar. Four partial responses (PR) were seen (4/48); 3 in the non-small cell lung cancer (NSCLC) cohort, measuring 40%, 57%, and 67% by RECIST, and 1 PR in a patient with ovarian cancer.

CONCLUSIONS

Tariquidar is well tolerated, with less observed systemic pharmacokinetic interaction than previous Pgp antagonists. Variable effects of tariquidar on retention of sestamibi in imageable lung cancers suggest that follow-up studies assessing tumor drug uptake in this patient population would be worthwhile.

Tumor and host factors that may limit efficacy of chemotherapy in non-small cell and small cell lung cancer

While chemotherapy provides useful palliation, advanced lung cancer remains incurable since those tumors that are initially sensitive to therapy rapidly develop acquired resistance. Resistance may arise from impaired drug delivery, extracellular factors, decreased drug uptake into tumor cells, increased drug efflux, drug inactivation by detoxifying factors, decreased drug activation or binding to target, altered target, increased damage repair, tolerance of damage, decreased proapoptotic factors, increased antiapoptotic factors, or altered cell cycling or transcription factors. Factors for which there is now substantial clinical evidence of a link to small cell lung cancer (SCLC) resistance to chemotherapy include MRP (for platinum-based combination chemotherapy) and MDR1/P-gp (for non-platinum agents). SPECT MIBI and Tc-TF scanning appears to predict chemotherapy benefit in SCLC. In non-small cell lung cancer (NSCLC), the strongest clinical evidence is for taxane resistance with elevated expression or mutation of class III beta-tubulin (and possibly alpha tubulin), platinum resistance and expression of ERCC1 or BCRP, gemcitabine resistance and RRM1 expression, and resistance to several agents and COX-2 expression (although COX-2 inhibitors have had minimal impact on drug efficacy clinically). Tumors expressing high BRCA1 may have increased resistance to platinums but increased sensitivity to taxanes. Limited early clinical data suggest that chemotherapy resistance in NSCLC may also be increased with decreased expression of cyclin B1 or of Eg5, or with increased expression of ICAM, matrilysin, osteopontin, DDH, survivin, PCDGF, caveolin-1, p21WAF1/CIP1, or 14-3-3sigma, and that IGF-1R inhibitors may increase efficacy of chemotherapy, particularly in squamous cell carcinomas. Equivocal data (with some positive studies but other negative studies) suggest that NSCLC tumors with some EGFR mutations may have increased sensitivity to chemotherapy, while K-ras mutations and expression of GST-pi, RB or p27kip1 may possibly confer resistance. While limited clinical data suggest that p53 mutations are associated with resistance to platinum-based therapies in NSCLC, data on p53 IHC positivity are equivocal. To date, resistance-modulating strategies have generally not proven clinically useful in lung cancer, although small randomized trials suggest a modest benefit of verapamil and related agents in NSCLC.

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.

Cost-effectiveness of 99mTc-sestamibi in predicting response to chemotherapy in patients with lung cancer: systematic review and meta-analysis

Multidrug resistance (MDR) is a major problem in lung cancer. (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) has been demonstrated to be a noninvasive marker for the diagnosis of MDR-related P glycoprotein and MDR-associated protein expression in various solid tumors. Studies have shown that (99m)Tc-MIBI could play a significant role in the management of lung cancer; for example, it could be used in the selection of patients for chemotherapy or radiotherapy or in combined protocols before the start of treatment. Accurate selection of chemosensitive patients with (99m)Tc-MIBI would result not only in effective treatment of patients but also in significant cost savings for health care providers. There is increasing pressure on health care providers to consider costs in medical decision making, particularly in the last decade, as several economic evaluations have appeared in the medical literature. The aims of this study were to undertake a systematic review of the performance of (99m)Tc-MIBI imaging in the assessment of treatment resistance in lung cancer and to use the findings of the review in a decision tree analysis of the potential cost-effectiveness of (99m)Tc-MIBI imaging in selecting lung cancer patients for chemotherapy.

METHODS

This study included a systematic review of the literature and a meta-analysis together with a cost-effectiveness analysis of studies with a decision tree analysis model.

RESULTS

Analysis of the studies revealed that the overall sensitivity of (99m)Tc-MIBI in identifying responders to chemotherapy was 94%, the specificity was 90%, and the accuracy was 92%. The sensitivity analysis revealed an incremental cost-effectiveness ratio of greater than pound30,000 ( approximately $42,900) for the strategy of treating all patients to recover the small loss of life expectancy (7.5 d) associated with the use of (99m)Tc-MIBI to preselect patients for chemotherapy.

CONCLUSION

(99m)Tc-MIBI SPECT can accurately predict which patients with lung cancer will respond to chemotherapy. The use of (99m)Tc-MIBI to preselect patients for chemotherapy has the potential to yield significant cost savings in the health care system without a significant loss of life expectancy for patients.

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.

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.

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.

Limitations of (99m)Tc tetrofosmin in assessing reversal effects of verapamil on the function of multi-drug resistance associated protein 1

BACKGROUND

Previous reports have demonstrated the feasibility of scintigraphic assessment of the multi-drug resistance (MDR) of tumours caused by ATP binding cassette (ABC) transporters by using Tc cationic tracers such as Tc tetrofosmin (TF). Furthermore, the potential of these tracers for evaluating the effects of reversal agents for MDR has been documented. However, most reversal agents simultaneously affect cationic ion transporters related to tracer accumulation in tumours.

METHODS

The uptake of Tc-TF was examined in the MCF7/WT cell line, a wild-type breast cancer cell line that does not exhibit MDR, and its subclonal etoposide resistant cell line MCF7/VP, which expresses high levels of MRP1, one of the multi-drug resistance associated proteins (MRPs), in the presence of increasing concentrations of verapamil, a classical MDR modulator. In the absence of verapamil, MCF7/VP cells showed significantly lower Tc-TF uptake than did MCF7/WT cells, indicating that Tc-TF is a substrate for MRP1. The presence of verapamil enhanced the uptake of Tc-TF in MCF7/VP cells. On the other hand, verapamil also increased tracer uptake in MCF7/WT cells, which was readily appreciated when the uptake values were corrected by viable cell numbers: an approximately 100% increase of Tc-TF uptake was observed in comparison with that in the absence of verapamil in viable MCF7/WT cells whereas a 100-200% increase occurred in viable MCF7/VP cells. In addition, verapamil prolonged the retention of radioactivity in both MCF7/WT cells and MCF7/VP cells.

CONCLUSION

These results suggest that cellular functions other than MRP1 function, probably cationic ion transporters, are simultaneously and significantly involved in the verapamil induced changes of cellular uptake of Tc-TF. Tc-TF scintigraphy may overestimate the reversal effects of modulators on chemoresistance caused by MRP1 when the modulators simultaneously affect ion transporters.

Thallium-201 SPECT in advanced non-small cell lung cancer: in relation with chemotherapeutic response, survival, distant metastasis and p53 status

PURPOSE

The aim of this study was to evaluate the relationship between 201Tl tumor uptake, chemotherapeutic response, metastasis, p53 status and survival in non-small cell lung cancer (NSCLC).

METHODS

A total of 23 patients underwent 201Tl SPECT. In 9 patients, 2nd 201Tl SPECT study were performed 1 week after the 3rd cycle of chemotherapy (ChT), and early (ER) and delayed (DR) tumor/normal lung ratios and retention indices (RI) were obtained. In 15 patients p53 status was assayed with immuno-histochemical staining. The patients were divided into subgroups after the 3rd cycle of ChT; responders [R(+) (n = 10)] and non-responders [R(-) (n = 13)], distant metastasis [(M1) n = 11] and [(M0) n = 12], and mutant p53 status [p(+) n = 7, p53(-) n = 8].

RESULTS

The differences for ER, DR and RI values between all of the subgroups were not statistically significant. ER and DR of responders decreased significantly after ChT; from to 2.46 to 1.36 (p = 0.04) and 2.29 to 1.53 (p = 0.04), respectively. In the non-responder group, both ER and DR slightly increased after ChT (p > 0.05).

CONCLUSION

Our results suggest that in NSCLC, there was a weak correlation between higher 201Tl ratios and positive response to chemotherapy, absence of distant metastasis, and p53(-) status. Significant 201Tl uptake decrease after chemotherapy indicates that delayed 201Tl uptake can be used in evaluating the chemotherapeutic response.

Positron emission tomography in lung cancer

Carcinoma of the lung is one of the most frequent malignancies and a major cause of mortality. The use of positron emission tomography (PET) has been extensively investigated in patients with carcinoma of the lung and has established clinical utility and cost-effectiveness in characterization of solitary pulmonary nodules and preoperative staging of carcinoma of the lung. Evolving applications in carcinoma of the lung include detection of recurrence, assessment of treatment response, radiotherapy planning, and prognosis. In addition, there is developing interest in combined anatomic/metabolic imaging and new tracer techniques, in particular gene expression imaging. This review aims to present existing data supporting the use of PET in carcinoma of the lung and to explore the evolving indications and future prospects of PET and lung cancer.

Predictive value of (99m)Tc sestamibi scintigraphy in the evaluation of doxorubicin based chemotherapy response in patients with advanced breast cancer

Resistance to doxorubicin based chemotherapy is a major therapeutic problem limiting advanced breast cancer treatment. 99mTc hexakis-2-methoxyisobutylisonitrile ((99m)Tc-MIBI) has been reported to be extruded from tumour cells by the P-glycoprotein and multidrug resistance protein encoded by MDR1 and MRP1 genes, respectively. These proteins are involved in the cellular efflux of several chemotherapeutic agents including doxorubicin. The aim of this study was to investigate the clinical value of a standard (99m)Tc-MIBI scintimammography technique in the prediction of response to chemotherapy in advanced breast cancer patients. Fifty-six lesions from 33 female patients with locally advanced (n=27) or recurrent breast cancer (n=6) were included in the study. MIBI scintigraphy was performed 2-8 days prior to chemotherapy (FAC regimen). Images were acquired 10 min and 1 h post-injection of 740-1110 MBq of (99m)Tc-MIBI. Tumour-to-normal background tissue uptake ratios were calculated on each lesion in the early (T/B(e)) and delayed phase of the study (T/B(d)). Both T/B(e) and T/B(d) ratios were significantly higher (P<0.0001) in responders (n=43) than nonresponders (n=13). Diagnostic values of (99m)Tc-MIBI in the prediction of chemotherapy response were evaluated using the arbitrary cut-off values of 1.5 for T/B(e) and 1.4 forT/B(d). Sensitivity, specificity, positive and negative predictive values were 88.4%, 92.3%, 97.4%, 70.6%; and 90.7%, 100.0%, 100.0%, 76.6%, for T/B(e) and T/B(d), respectively. We conclude that (99m)Tc-MIBI scintigraphy may be a clinically valuable tool for guiding chemotherapy in advanced breast cancer patients.

Quantified 99mTc-MIBI scintigraphy for predicting chemotherapy response in breast cancer patients: factors that influence the level of 99m Tc-MIBI uptake

The aim of this study was to establish whether tumour uptake of 99mTc-MIBI can predict response to chemotherapy in patients with breast carcinoma. Forty women suffering from breast carcinoma confirmed by tumour biopsy were studied prospectively. Fifteen patients subsequently underwent surgery and 25 were candidates for neoadjuvant chemotherapy. Breast scintigraphy was performed and planar and tomographic views (single photon emission computed tomography (SPECT)) were obtained after injection of 740 MBq of 99mTc-MIBI. The tumoural uptake was quantified by computer analysis. P-glycoprotein was evaluated by immunohistochemistry only in operable patients. The response to chemotherapy was evaluated at 3 months upon completion of treatment. The results of this study showed no relationship between 99mTc-MIBI uptake and the histological type or tumour size. There was an inverse correlation with the degree of tumour differentiation (P<0.05). 99mTc-MIBI uptake in negative P-glycoprotein lesions (2.36+/-1.72) was higher than in positive P-glycoprotein lesions (1.53+/-1.29), although the difference was not statistically significant. Lesions which responded to chemotherapy (16) showed higher 99mTc-MIBI uptake (7.70+/-5.20) than non-responding lesions (nine) (2.21+/-1.0) (P<0.001). In conclusion, there is a correlation between 99mTc-MIBI uptake in breast cancer and response to chemotherapy. Furthermore, 99mTc-MIBI uptake may be influenced by other factors such as the degree of tumour differentiation or tumour P-glycoprotein levels.