Silvana Del Vecchio

In vivo detection of multidrug-resistant (MDR1) phenotype by technetium-99m sestamibi scan in untreated breast cancer patients

Technetium-99m sestamibi is a transport substrate recognised by the multidrug-resistant P-glycoprotein (Pgp). To test whether99mTc-sestamibi efflux is enhanced in breast carcinomas overexpressing Pgp, we determined the efflux rates of99mTc-sestamibi and Pgp levels in tumours from 30 patients with untreated breast carcinoma. Patients were intravenously injected with 740 MBq of99mTc-sestamibi and underwent a 15-min dynamic study followed by the acquisition of static planar images at 0.5, 1, 2 and 4 h. Tumour specimens were obtained from each patient 24 h after99mTc-sestamibi scan and Pgp levels were determined using125I-MRK16 monoclonal antibody and in vitro quantitative autoradiography. All breast carcinomas showed high uptake of99mTc-sestamibi and data from region of interest analysis on sequential images were fitted with a monoexponential function. The efflux rates of99mTc-sestamibi, calculated from decay-corrected time-activity curves, ranged between 0.00121 and 0.01690 min−1 and were directly correlated with Pgp levels measured in the same tumours (r=0.62;P<0.001). Ten out of 30 breast carcinomas (33%) contained 5 times more Pgp than benign breast lesions and showed a mean concentration of 5.73±1.63 pmol/g of tumour (group A). The remaining 20 breast carcinomas had a mean Pgp concentration of 1.29±0.64 pmol/g (group B), equivalent to that found in benign breast lesions.99mTc-sestamibi efflux from tumours of group A was 2.7 times higher than that observed in tumours of group B (0.00686±0.00390 min−1 vs 0.00250±0.00090 min−1,P<0.001). The in vivo functional test with99mTc-sestamibi showed a sensitivity and a specificity of 80% and 95%, respectively. In conclusion, the efflux rate of99mTc-sestamibi may be used for the in vivo identification of the multidrug resistant (MDR1) phenotype in untreated breast cancer patients.

18F-FDG PET/CT, 99mTc-MIBI, and MRI in evaluation of patients with multiple myeloma.

New imaging techniques have been introduced to assess the extent and severity of disease in multiple myeloma (MM) patients. The aim of our study was to compare newer imaging modalities—such as 18F-FDG PET/CT, 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) scintigraphy, and MRI—to assess their relative contribution in the evaluation of MM patients at diagnosis. Methods: Thirty-three newly diagnosed patients with MM were prospectively studied. Diagnosis and staging were made according to standard criteria. All patients underwent whole-body 18F-FDG PET/CT, whole-body 99mTc-MIBI, and MRI of the spine and pelvis within 10 d, and imaging findings were compared. Results: 18F-FDG PET/CT was positive in 32 patients (16 focal uptake, 3 diffuse uptake, 13 focal and diffuse uptake), 99mTc-MIBI was positive in 30 patients (6 focal, 11 diffuse, 13 focal and diffuse uptake), and MRI of the spine and pelvis was positive in 27 patients (6 focal, 13 diffuse, 8 focal and diffuse uptake). 18F-FDG PET/CT showed a total of 196 focal lesions (178 in bones and 18 in soft tissues), of which 121 were in districts other than the spine and pelvis, whereas 99mTc-MIBI visualized 63 focal lesions (60 in bones and 3 in soft tissues), of which 53 were in districts other than the spine and pelvis. In the spinal and pelvic regions, 18F-FDG PET/CT detected 75 focal lesions (35 in spine and 40 in pelvis), 99mTc-MIBI visualized 10 focal lesions (1 in spine and 9 in pelvis), and MRI detected 51 focal lesions (40 in spine and 11 in pelvis). Conclusion: In whole-body analysis, 18F-FDG PET/CT performed better than 99mTc-MIBI in the detection of focal lesions, whereas 99mTc-MIBI was superior in the visualization of diffuse disease. In the spine and pelvis, MRI was comparable to 18F-FDG PET/CT and 99mTc-MIBI in the detection of focal and diffuse disease, respectively. Because myelomatous lesions may often occur out of spinal and pelvic regions, MRI should be reserved to the evaluation of bone marrow involvement of these districts, whereas 18F-FDG PET/CT can significantly contribute to an accurate whole-body evaluation of MM patients. Finally, whole-body 99mTc-MIBI, despite its limited capacity in detecting focal lesions, may be an alternative option when a PET facility is not available.

Anti-murine antibody response to mouse monoclonal antibodies: Clinical findings and implications

Many patients given murine monoclonal antibody become immune to these proteins. Important factors in the development of immunity are (1) the patients ability to become immune and (2) whether whole immunoglobulin or Fab fragment was used. Circulating anti-murine antibodies increase the murine antibody plasma clearance and the liver or spleen uptake while reducing tumor targeting. Clearance rates and radioassay measured levels of anti-murine antibodies are related to serum murine/anti-murine antibody complexes. Unlabeled murine antibody displaces radiolabeled antibody from these complexes.

Metabolic Tumor Volume Assessed by 18F-FDG PET/CT for the Prediction of Outcome in Patients with Multiple Myeloma

18F-FDG PET/CT allows the direct measurement of metabolic tumor burden in a variety of different malignancies. The aim of this study was to assess whether metabolic tumor volume (MTV) determined by 18F-FDG PET/CT could be used in the prediction of progression-free and overall survival in multiple myeloma patients. Methods: Forty-seven patients (18 women, 29 men; mean age ± SD, 63 ± 11 y) with stage IIIA disease who had undergone whole-body 18F-FDG PET/CT were retrospectively evaluated. Images underwent a 3-dimensional region-of-interest analysis including all focal lesions with a maximum standardized uptake value > 2.5. The MTV of each lesion was calculated using an automated contouring program based on the standardized uptake value and developed with a threshold of 40% of the maximum standardized uptake value. The total MTV of each patient was defined as the sum of metabolic volume of all focal lesions. Patients were treated and then subjected to a mean follow-up period of 24 mo. Results: In the 47 patients studied, MTV range was 1.3–316.3 mL, with a median of 23.7 mL. A direct, significant correlation was found between MTV and the percentage of diffuse infiltration of bone marrow by plasma cells (r = 0.46, P = 0.006), whereas hemoglobin levels were inversely correlated with MTV (r = −0.56, P = 0.0001). At follow-up, patients who developed progressive disease (n = 18) showed a significantly higher MTV (74.7 ± 19.3 vs. 29.8 ± 5.1 mL, P = 0.009) than patients without progressive disease (n = 29). Furthermore, patients who died of myeloma (n = 9) had a significantly higher MTV (123.2 ± 30.6 vs. 28.9 ± 4.2 mL, P = 0.0001) than survivors (n = 38). No differences in age, plasma cell infiltration, M protein, albumin, β2-microglobulin, performance status, International Staging System score, and presence or absence of a bone marrow transplant were found between groups. The MTV cutoff level was determined by receiver-operating-characteristic curve analysis, and the best discriminative value found for predicting progression-free and overall survival was 42.2 and 77.6 mL, respectively. By Kaplan–Meier analysis and log-rank testing, progression-free and overall survival at follow-up were significantly better in patients showing an MTV lower than the cutoff than in those having an MTV higher than the cutoff (χ2 = 3.9, P = 0.04, and χ2 = 56.3, P < 0.0001, respectively). Conclusion: The direct measurement of tumor burden obtained by calculating MTV on 18F-FDG PET/CT images may be used in the prediction of progression-free and overall survival in myeloma patients.

Sphingosine Kinase 1 Overexpression Contributes to Cetuximab Resistance in Human Colorectal Cancer Models

Purpose: Although the anti–EGF receptor (EGFR) monoclonal antibody cetuximab is an effective strategy in colorectal cancer therapy, its clinical use is limited by intrinsic or acquired resistance. Alterations in the “sphingolipid rheostat”—the balance between the proapoptotic molecule ceramide and the mitogenic factor sphingosine-1-phosphate (S1P)—due to sphingosine kinase 1 (SphK1) overactivation have been involved in resistance to anticancer-targeted agents. Moreover, cross-talks between SphK1 and EGFR-dependent signaling pathways have been described. Experimental design: We investigated SphK1 contribution to cetuximab resistance in colorectal cancer, in preclinical in vitro/in vivo models, and in tumor specimens from patients. Results: SphK1 was found overexpressed and overactivated in colorectal cancer cells with intrinsic or acquired resistance to cetuximab. SphK1 contribution to resistance was supported by the demonstration that SphK1 inhibition by N,N-dimethyl-sphingosine or silencing via siRNA in resistant cells restores sensitivity to cetuximab, whereas exogenous SphK1 overexpression in sensitive cells confers resistance to these agents. Moreover, treatment of resistant cells with fingolimod (FTY720), a S1P receptor (S1PR) antagonist, resulted in resensitization to cetuximab both in vitro and in vivo, with inhibition of tumor growth, interference with signal transduction, induction of cancer cells apoptosis, and prolongation of mice survival. Finally, a correlation between SphK1 expression and cetuximab response was found in colorectal cancer patients. Clin Cancer Res; 19(1); 138–47. ©2012 AACR.

Sestamibi and FDG-PET scans to support diagnosis of jaw osteonecrosis.

Osteonecrosis of the maxillary or mandibular bone is an infrequent but often severe event occurring in patients who undergo prolonged treatment with bisphosphonates. Histology is in some cases mandatory to differentiate it from neoplastic osteolysis, but a biopsy can further contribute to bone damage. Functional imaging obtained by a tracer that shows oncotropic properties, such as Tc99m-sestamibi, in comparison to a non-tumor-specific substance such as FDG-PET, can support the differential diagnosis, thus avoiding invasive procedures. Four patients affected by multiple myeloma and jaw osteonecrosis were prospectively evaluated by sestamibi and FDG-PET scans. Local diagnosis was performed by clinical, radiological and, in some cases, histological evaluations. Each patient was studied by Tc99m-sestamibi, performed by planar anterior and posterior whole-body scans and SPECT of the head and neck, and by PET/CT. Two nuclear medicine physicians, unaware of the final diagnosis, reviewed the images. No sestamibi uptake was evident in the four patients with jaw osteonecrosis, while FDG-PET/CT showed focal uptake in all of them. Our study suggests that the combined use of sestamibi scintigraphy and FDG-PET/CT could support the clinical diagnosis of oral osteonecrosis avoiding the risks of a surgical biopsy. Studies on higher number of patients are necessary to validate these preliminary observations.

99mTc-MIBI in the evaluation of breast cancer biology

A major area of interest in nuclear medicine is the scintigraphic in vivo evaluation of complex cellular processes involved in tumour growth, progression and response to treatment with the aim of defining the biological properties that may orient clinicians towards different adjustments of therapy in individual patients. In the last decade, 99mTc-labelled lipophilic cations emerged as suitable tools to trace specific cellular processes and functions in a variety of malignant tumours, including breast cancer. Among these agents, 99mTc-methoxyisobutylisonitrile (MIBI) is the most widely evaluated tracer and may serve as a paradigm for this class of compounds. Many clinical studies have been performed to correlate 99mTc-MIBI uptake or clearance with histological, molecular and biochemical markers of various cellular processes, including apoptosis, proliferation, P-glycoprotein expression and neoangiogenesis. The final picture emerging from these studies is that the early tracer uptake reflects the mitochondrial status, which is affected by both apoptosis and proliferation, whereas the tracer clearance reflects the activity of drug transporters such as P-glycoprotein. On the basis of the imaging parameter chosen for the analysis of 99mTc-MIBI scan in breast cancer patients, the biological information provided may be related to different cellular processes that ultimately govern tumour response to treatment.

Reversal of Warburg Effect and Reactivation of Oxidative Phosphorylation by Differential Inhibition of EGFR Signaling Pathways in Non–Small Cell Lung Cancer

Purpose: One of the hallmarks of cancer cells is the excessive conversion of glucose to lactate under normoxic conditions, also known as the Warburg effect. Here, we tested whether the targeted inhibition of EGFR may revert this effect and reactivate mitochondrial oxidative phosphorylation in non–small cell lung cancer (NSCLC). Experimental Design: Sensitive (HCC827) and resistant (H1975 and H1993) NSCLC cells were treated with a panel of EGFR or MET inhibitors, and then tested for changes of EGFR signaling, glycolytic cascade, and mitochondrial function. Silencing of key glycolytic enzymes was then performed with targeted siRNAs. Furthermore, tumor-bearing nude mice treated with EGFR inhibitors were evaluated with 18F-FDG PET/CT and tumors were analyzed for glycolytic and mitochondrial proteins. Results: Effective inhibition of EGFR signaling in NSCLC cells induced a dramatic reduction of hexokinase II (HKII) and phospho-pyruvate kinase M2 (p-PKM2, Tyr105) levels as well as an upregulation of mitochondrial complexes subunits (OXPHOS). Accordingly, a decreased lactate secretion and increased intracellular ATP levels were also observed in response to EGFR inhibitors. Downregulation of HKII and PKM2 by targeted siRNA transfection did not cause upregulation of OXPHOS but enhanced the effects of EGFR TKIs. Conversely, selective inhibition of AKT and ERK1/2 caused OXPHOS upregulation and glycolysis inhibition, respectively. Similar findings were obtained in tumors from animals treated with appropriate EGFR inhibitors. Conclusions: Our findings indicate that EGFR inhibitors may reactivate oxidative phosphorylation of cancer cells and provide a mechanistic clue for the rational combination of agents targeting EGFR-dependent proliferation and glucose metabolism in cancer therapy. Clin Cancer Res; 21(22); 5110–20. ©2015 AACR.

Predictive value of technetium-99m sestamibi in patients with multiple myeloma and potential role in the follow-up

Technetium-99m 2-methoxyisobutylisonitrile (99mTc-MIBI or setamibi) has recently been proposed for use in the evaluation of multiple myeloma (MM). The aims of this study were to investigate its potential predictive value in patients with MM and its possible role in the follow-up. Thirty patients with MM who had undergone two 99mTc-MIBI scintigraphic studies at least 2 months apart constituted the study group; 22 of them received chemotherapy in the interval between the two scans. The scans were classified as showing pattern N when only physiological uptake was present, pattern D when diffuse bone marrow uptake was observed, pattern F when areas of focal uptake of the tracer were evident, and pattern F+D when both D and F patterns were observed. Comparative 99mTc-MIBI scintigraphy was considered indicative of disease progression when there was a worsening of the pattern (i.e. from N to D, or from N or D to F or to F+D) or an increase in the pattern D semiquantitative score. It was considered indicative of disease improvement when the opposite trend was observed; otherwise, it was considered to document a stable condition. A significant association was observed between the baseline scintigraphic pattern and clinical status at follow-up in the group of patients evaluated after chemotherapy (χ2=16.7, P<0.05). A negative baseline 99mTc-MIBI scintigram showed a high predictive accuracy (100%) for remission, while the presence of pattern F or F+D was often associated with a less favourable outcome. A multivariate analysis showed that 99mTc-MIBI uptake pattern has an added value in relation to known prognostic variables such as C-reactive protein. 99mTc-MIBI scintigraphy patterns at follow-up were significantly associated with the clinical status evaluated after chemotherapy (χ2=32.6, P<0.0001). Considering pattern N as indicating remission, pattern D stable condition, and pattern F or F+D progressive disease, a high concordance between scintigraphic findings and clinical status was found in the 22 patients undergoing chemotherapy (91%). Variation in 99mTc-MIBI findings comparing baseline and follow-up evaluations was significantly associated with clinical status both in patients undergoing chemotherapy (χ2=26.5, P<0.0005) and in those not undergoing chemotherapy (χ2=8.0, P<0.005). In conclusion, the results of this study suggest a prognostic value of 99mTc-MIBI scintigraphy in patients with MM and a potential role during the follow-up.

Scintimammography with 99mTc-MIBI versus dynamic MRI for non-invasive characterization of breast masses.

Abstract. Although mammography remains the technique of choice for the early detection of breast cancer, several imaging techniques, including scintimammography and magnetic resonance imaging (MRI), have recently been proposed as adjuncts for this purpose and included in many diagnostic protocols. This study was undertaken to assess the clinical accuracy of scintimammography with technetium-99m methoxyisobutylisonitrile (MIBI) and contrast-enhanced MRI in the detection of primary breast carcinoma in patients with equivocal mammographic findings. Forty-nine patients with a suspicious breast mass detected either by physical examination or by mammography and ultrasound (US) were studied. All patients underwent scintimammography and dynamic contrast-enhanced MRI 1 week apart. The results of the two techniques were compared and correlated to the final diagnoses. Two independent readers reported the scans using a four-point confidence scale. The areas under the receiver operator characteristic (ROC) curves were obtained. Scintimammography showed an accuracy for tumour detection of 84%, with a sensitivity of 80% and a specificity of 88%. MRI showed an accuracy of 86%, with a sensitivity and specificity of 96% and 75%, respectively. Comparison of the two areas under the ROC curves showed no significant differences between MRI, 0.91±0.05 (mean±SD), and scintimammography, 0.88±0.05 (P=0.9). It is concluded that dynamic MRI and scintimammography possess comparable accuracy in the diagnosis of primary breast carcinoma in patients with equivocal mammographic or US findings.