Coefficient of variation and texture analysis of 18F-FDG PET/CT images for the prediction of outcome in patients with multiple myeloma.

In multiple myeloma (MM) bone marrow infiltration by monoclonal plasma cells can occur in both focal and diffuse manner, making staging and prognosis rather difficult. The aim of our study was to test whether texture analysis of 18 F-2-deoxy-d-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) images can predict survival in MM patients. Forty-six patients underwent 18 F-FDG-PET/CT before treatment. We used an automated contouring program for segmenting the hottest focal lesion (FL) and a lumbar vertebra for assessing diffuse bone marrow involvement (DI). Maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean) and texture features such as Coefficient of variation (CoV), were obtained from 46 FL and 46 DI. After a mean follow-up of 51 months, 24 patients died of myeloma and were compared to the 22 survivors. At univariate analysis, FL SUVmax (p = 0.0453), FL SUVmean (p = 0.0463), FL CoV (p = 0.0211) and DI SUVmax (p = 0.0538) predicted overall survival (OS). At multivariate analysis only FL CoV and DI SUVmax were retained in the model (p = 0.0154). By Kaplan-Meier method and log-rank testing, patients with FL CoV below the cut-off had significantly better OS than those with FL CoV above the cut-off (p = 0.0003), as well as patients with DI SUVmax below the threshold versus those with DI SUVmax above the threshold (p = 0.0006). Combining FL CoV and DI SUVmax by using their respective cut-off values, a statistically significant difference was found between the resulting four survival curves (p = 0.0001). Indeed, patients with both FL CoV and DI SUVmax below their respective cut-off values showed the best prognosis. Conventional and texture parameters derived from 18F-FDG PET/CT analysis can predict survival in MM patients by assessing the heterogeneity and aggressiveness of both focal and diffuse infiltration.

Liposomal doxorubicin supercharge-containing front-line treatment in patients with advanced-stage diffuse large B-cell lymphoma or classical Hodgkin lymphoma: Preliminary results of a single-centre phase II study.

We evaluated the impact of liposomal doxorubicin (NPLD) supercharge-containing therapy on interim fluorodeoxyglucose positron emission tomography (interim-FDG-PET) responses in high-risk diffuse large B-cell lymphoma (DLBCL) or classical Hodgkin lymphoma (c-HL). In this phase II study (2016-2021), 81 adult patients with advanced-stage DLBCL (n = 53) and c-HL (n = 28) received front-line treatment with R-COMP-dose-intensified (DI) and MBVD-DI. R-COMP-DI consisted of 70 mg/m2 of NPLD plus standard rituximab, cyclophosphamide, vincristine and prednisone for three cycles (followed by three cycles with NPLD de-escalated at 50 mg/m2 ); MBVD-DI consisted of 35 mg/m2 of NPLD plus standard bleomycin, vinblastine and dacarbazine for two cycles (followed by four cycles with NPLD de-escalated at 25 mg/m2 ). Patients underwent R-COMP-DI and MBVD-DI with a median dose intensity of 91% and 94% respectively. At interim-FDG-PET, 72/81 patients (one failed to undergo interim-FDG-PET due to early death) had a Deauville score of ≤3. At end of treatment, 90% of patients reached complete responses. In all, 20 patients had Grade ≥3 adverse events, and four of them required hospitalisation. At a median 21-months of follow-up, the progression-free survival of the entire population was 77.3% (95% confidence interval 68%-88%). Our data suggest that the NPLD supercharge-driven strategy in high-risk DLBCL/c-HL may be a promising option to test in phase III trials, for improving negative interim-FDG-PET cases incidence.

Visual and volumetric parameters by 18F-FDG-PET/CT: a head to head comparison for the prediction of outcome in patients with multiple myeloma.

In multiple myeloma (MM) patients, 18F-FDG-PET/CT allows either the detection of disease spread by using visual parameters based on the Italian Myeloma criteria for PET Use (IMPeTUs) or the direct measurement of metabolic tumor burden by volume-based parameters such as metabolic tumor volume (MTV). The purpose is to evaluate the contribution of visual and volumetric parameters in the prediction of progression-free survival (PFS) and overall survival (OS) in MM patients. Forty-seven patients in stage IIIA who had undergone whole-body 18F-FDG-PET/CT were retrospectively evaluated. In each patient, visual parameters were determined and compared with volumetric parameters for PFS and OS prediction after a mean follow-up period of 53 months. Among the visual and volumetric parameters tested, a statistically significant difference was found between maximum standardized uptake value, MTV, total lesion glycolysis, and number of lytic lesions of patients with (n = 26) or without (n = 21) progression (p = 0.0400, p = 0.0065, p = 0.015, and p = 0.0220, respectively) and of dead (n = 24) vs survivors (n = 23) (p = 0.0171, p = 0.0037, p = 0.0060, and p = 0.0270, respectively). At univariate and multivariate analysis, MTV and hemoglobin were predictive of both PFS (p = 0.008) and OS (p = 0.0026). The best MTV discriminative value assessed by receiver operating characteristic curve analysis for predicting both PFS and OS was 39.4 ml. By Kaplan-Meier analysis and log-rank test, PFS and OS were significantly better in patients with MTV ≤ 39.4 ml (p = 0.0004 and p = 0.0001, respectively) as compared with those having an MTV higher than the cutoff. The volume-based parameter MTV determined by 18F-FDG-PET/CT may be used in the prediction of PFS and OS in myeloma patients.

Preclinical imaging for targeting cancer immune evasion.

Novel anticancer immunotherapy strategies such as immune checkpoint blockade have been successfully employed in patients with a variety of cancers and became a therapeutic option in the treatment of several malignancies. However, long-term durable responses to immune checkpoint inhibitors are currently limited to a fraction of patients raising the need of an accurate selection of potentially responding patients. Although several biomarkers have been proposed for patient selection and prediction of response to immune checkpoint blockade, none can be considered as an absolute selection criterion. Whole-body imaging with tracers recognizing targets for immunotherapy by allowing visualization of target expression in all tumor and extratumoral sites at baseline and during disease evolution may provide reliable predictive imaging biomarkers. Here we will provide an overview of preclinical imaging studies aiming at the development and validation of tracers recognizing targets for immunotherapy that can be used for selection and monitoring of patients undergoing immunotherapy and for testing novel immunotherapeutic agents or strategies. Furthermore, we will focus on the selection of animal models based on the main purpose of the study and implications for clinical transfer of the results.

2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography in primary extranodal lymphomas: treatment response evaluation and prognosis.

BACKGROUND: We evaluated the role of [18F]FDG PET/CT in tumor response assessment and prognosis of primary extranodal lymphoma (PEL) patients. METHODS: We examined retrospectively, 56 PEL patients: 31 with aggressive diffuse large B cell lymphoma (DLBCL) and 25 with indolent lymphoma (20 mucosa-associated lymphoid tissue lymphoma and five follicular lymphoma). All patients had undergone [18F]FDG PET/CT at diagnosis (PET-I) and 50 of them also after therapy (PET-II). Moreover, 52 patients were subjected to a mean follow-up period of 76 months. RESULTS: PET-I was positive in 50 (89%) patients (mean SUVmax 10.3±6.7). In the assessment of tumor response, according to Lugano classification, 45 patients showed complete metabolic response (CMR), four patients had partial metabolic response (PMR) and one had progressive metabolic disease (PMD). Based on 66% ΔSUVmax cut-off, among CMR patients, 41 showed a ΔSUVmax>66% whereas among non-responders, four patients showed a ΔSUVmax<66%. At follow-up, univariate analysis showed that age, performance status, prognostic index, ΔSUVmax and Lugano classification predicted progression-free survival (PFS) (P<0.05), while, performance status, prognostic index, ΔSUVmax and Lugano classification predicted overall survival (OS) (P<0.05). At multivariate analysis only Lugano classification was retained in the model for prediction of both PFS (P<0.05) and OS (P<0.05). By Kaplan-Meier analysis and log-rank testing both PFS and OS were significantly better in patients in CMR as compared to patients in PMR or PMD according to Lugano classification (P<0.01). CONCLUSIONS: [18F]FDG PET/CT represents a useful tool in the detection of disease response and in the evaluation of outcome in PEL patients.

Coordinate Modulation of Glycolytic Enzymes and OXPHOS by Imatinib in BCR-ABL Driven Chronic Myelogenous Leukemia Cells.

Since many oncogenes, including BCR-ABL, may promote the acquisition and maintenance of the glycolytic phenotype, we tested whether treatment of BCR-ABL-driven human leukemia cells with imatinib, a selective BCR-ABL inhibitor, can modulate the expression of key glycolytic enzymes and mitochondrial complex subunits thus causing alterations of glucose metabolism. BCR-ABL-driven K562 and KCL-22 cells were incubated with increasing concentrations of imatinib to preliminarily test drug sensitivity. Then untreated and treated cells were analyzed for levels of BCR-ABL signaling mediators and key proteins of glycolytic cascade and oxidative phosphorylation. Effective inhibition of BCR-ABL caused a concomitant reduction of p-ERK1/2, p-AKT, phosphorylated form of STAT3 (at Tyr705 and Ser727), c-Myc and cyclin D1 along with an increase of cleaved PARP and caspase 3 at 48 h after treatment. Furthermore, a strong reduction of the hexokinase II (HKII), phosphorylated form of PKM2 (at Tyr105 and Ser37) and lactate dehydrogenase A (LDH-A) was observed in response to imatinib along with a strong upregulation of mitochondrial complexes (OXPHOS). According to these findings, a significant reduction of glucose consumption and lactate secretion along with an increase of intracellular ATP levels was observed in response to imatinib. Our findings indicate that imatinib treatment of BCR-ABL-driven human leukemia cells reactivates mitochondrial oxidative phosphorylation thus allowing potential co-targeting of BCR-ABL and OXPHOS.

Neutrophil Extracellular Traps as an Adhesion Substrate for Different Tumor Cells Expressing RGD-Binding Integrins.

Neutrophil extracellular traps (NETs), in addition to their function as a host defense mechanism, play a relevant role in thrombus formation and metastatic dissemination of cancer cells. Here we screened different cancer cell lines endogenously expressing a variety of integrins for their ability to bind to NETs. To this end, we used NETs isolated from neutrophil-like cells as a substrate for adhesion assays of HT1080, U-87 MG, H1975, DU 145, PC-3 and A-431 cells. Levels of α5, αIIb, αv, ß1, ß3 and ß5 chains were determined by western blot analysis in all cell lines and levels of whole integrins on the plasma membrane were assessed by fluorescence-activated cell sorting (FACS) analysis. We found that high levels of α5ß1, αvß3 and αvß5 enhance cell adhesion to NETs, whereas low expression of α5ß1 prevents cell attachment to NETs. Excess of cyclic RGD peptide inhibited cell adhesion to NETs by competing with fibronectin within NETs. The maximal reduction of such adhesion was similar to that obtained by DNase 1 treatment causing DNA degradation. Our findings indicate that NETs from neutrophil-like cells may be used as a substrate for large screening of the adhesion properties of cancer cells expressing a variety of RGD-binding integrins.

Machine Learning and Texture Analysis of [18F]FDG PET/CT Images for the Prediction of Distant Metastases in Non-Small-Cell Lung Cancer Patients.

The aim of our study was to predict the occurrence of distant metastases in non-small-cell lung cancer (NSCLC) patients using machine learning methods and texture analysis of 18F-labeled 2-deoxy-d-glucose Positron Emission Tomography/Computed Tomography {[18F]FDG PET/CT} images. In this retrospective and single-center study, we evaluated 79 patients with advanced NSCLC who had undergone [18F]FDG PET/CT scan at diagnosis before any therapy. Patients were divided into two independent training (n = 44) and final testing (n = 35) cohorts. Texture features of primary tumors and lymph node metastases were extracted from [18F]FDG PET/CT images using the LIFEx program. Six machine learning methods were applied to the training dataset using the entire panel of features. Dedicated selection methods were used to generate different combinations of five features. The performance of selected machine learning methods applied to the different combinations of features was determined using accuracy, the confusion matrix, receiver operating characteristic (ROC) curves, and area under the curve (AUC). A total of 104 and 78 lesions were analyzed in the training and final testing cohorts, respectively. The support vector machine (SVM) and decision tree methods showed the highest accuracy in the training cohort. Seven combinations of five features were obtained and introduced in the models and subsequently applied to the training and final testing cohorts using the SVM and decision tree. The accuracy and the AUC of the decision tree method were higher than those obtained with the SVM in the final testing cohort. The best combination of features included shape sphericity, gray level run length matrix_run length non-uniformity (GLRLM_RLNU), Total Lesion Glycolysis (TLG), Metabolic Tumor Volume (MTV), and shape compacity. The combination of these features with the decision tree method could predict the occurrence of distant metastases with an accuracy of 74.4% and an AUC of 0.63 in NSCLC patients.

Coefficient of Variation in Metastatic Lymph Nodes Determined by 18F-FDG PET/CT in Patients with Advanced NSCLC: Combination with Coefficient of Variation in Primary Tumors.

Purpose The aim of the present study was to test whether the coefficient of variation (CoV) of 18F-FDG PET/CT images of metastatic lymph nodes and primary tumors may predict clinical outcome in patients with advanced non-small cell lung cancer (NSCLC). Materials and Methods Fifty-eight NSCLC patients who had undergone 18F-FDG PET/CT at diagnosis were evaluated. SUVmax, SUVmean, CoV, MTV and TLG were determined in targeted lymph nodes and corresponding primary tumors along with Total MTV (MTVTOT) and Whole-Body TLG (TLGWB) of all malignant lesions. Univariate analysis was performed using Cox proportional hazards regression whereas the Kaplan-Meier method and log-rank tests were used for survival analysis. Results Fifty-eight metastatic lymph nodes were analyzed and average values of SUVmax, SUVmean, CoV, MTV and TLG were 11.89 ± 8.54, 4.85 ± 1.90, 0.37 ± 0.16, 46.16 ± 99.59 mL and 256.84 ± 548.27 g, respectively, whereas in primary tumors they were 11.92 ± 6.21, 5.47 ± 2.34, 0.36 ± 0.14, 48.03 ± 64.45 mL and 285.21 ± 397.95 g, respectively. At univariate analysis, overall survival (OS) was predicted by SUVmax (p = 0.0363), SUVmean (p = 0.0200) and CoV (p = 0.0139) of targeted lymph nodes as well as by CoV of primary tumors (p = 0.0173), MTVTOT (p = 0.0007), TLGWB (p = 0.0129) and stage (p = 0.0122). Using Kaplan-Meier analysis, OS was significantly better in patients with CoV of targeted lymph nodes ≤ 0.29 than those with CoV > 0.29 (p = 0.0147), meanwhile patients with CoV of primary tumors > 0.38 had a better prognosis compared to those with CoV ≤ 0.38 (p = 0.0137). Finally, we combined the CoV values of targeted lymph nodes and primary tumors in all possible arrangements and a statistically significant difference was found among the four survival curves (p = 0.0133). In particular, patients with CoV of targeted lymph nodes ≤ 0.29 and CoV of primary tumors > 0.38 had the best prognosis. Conclusions The CoV of targeted lymph nodes combined with the CoV of primary tumors can predict prognosis of NSCLC patients.

Sorafenib in advanced iodine-refractory differentiated thyroid cancer: efficacy, safety and exploratory analysis of role of serum thyroglobulin and FDG-PET.

CONTEXT: Radioactive iodine is a crucial tool for treatment of differentiated thyroid cancer (DTC). In 5% of cases, DTCs lose I-131 avidity and assume an aggressive behaviour. Treatment options for iodine-refractory DTC are limited. We report the experience of off-label use of the tyrosine kinase inhibitor sorafenib for treatment of advanced iodine-refractory DTC. DESIGN: Patients with progressive DTC refractory to radioactive iodine were treated with sorafenib used off-label independently from their performance status. Primary study end-points were radiological response, progression-free survival (PFS) and safety. Secondary end-points were site-specific radiological response and overall survival (OS). An exploratory analysis of the role of serum thyroglobulin (Tg) and fluorodeoxyglucose (FDG) positron emission tomography (PET) was performed. RESULTS: A total of 17 patients were included in the study. Median follow-up was 15·5 months. Clinical benefit was obtained in 71% of subjects (30% partial response and 41% stable disease). Sorafenib was mostly well tolerated, but a high incidence of fatal events was reported (three patients died from severe bleeding events and two from cardiac arrest). Median PFS was 9 months. Median OS was 10 months. The best responses were observed in lymph nodes and lung. Baseline Tg levels and the Tg response to treatment were correlated to both radiological response and PFS. Baseline FDG-PET assessment and early FDG-PET response were correlated to radiological response. CONCLUSIONS: Sorafenib allows morphological disease control in the majority of patients with iodine-refractory DTC. Progression-free survival and overall survival were lower than in previous studies as a consequence of the worse clinical condition of our patients. Sorafenib is mostly well tolerated but could have been responsible for the reported fatal events. Baseline Tg and the Tg response to treatment could be useful for predicting morphological response and clinical outcome. Early FDG-PET response could be helpful for the timely identification of nonresponding patients.

Diagnosis, Management and Theragnostic Approach of Gastro-Entero-Pancreatic Neuroendocrine Neoplasms.

Gastro-entero-pancreatic neuroendocrine neoplasms (GEP-NENs) constitute an ideal target for radiolabeled somatostatin analogs. The theragnostic approach is able to combine diagnosis and therapy by the identification of a molecular target that can be diagnosed and treated with the same radiolabeled compound. During the last years, advances in functional imaging with the introduction of somatostatin analogs and peptide receptor radionuclide therapy, have improved the diagnosis and treatment of GEP-NENs. Moreover, PET/CT imaging with 18F-FDG represents a complementary tool for prognostic evaluation of patients with GEP-NENs. In the field of personalized medicine, the theragnostic approach has emerged as a promising tool in diagnosis and management of patients with GEP-NENs. The aim of this review is to summarize the current evidence on diagnosis and management of patients with GEP-NENs, focusing on the theragnostic approach.

Heterogeneity of Glycolytic Phenotype Determined by 18F-FDG PET/CT Using Coefficient of Variation in Patients with Advanced Non-Small Cell Lung Cancer.

We investigated the role of Coefficient of Variation (CoV), a first-order texture parameter derived from 18F-FDG PET/CT, in the prognosis of Non-Small Cell Lung Cancer (NSCLC) patients. Eighty-four patients with advanced NSCLC who underwent 18F-FDG PET/CT before therapy were retrospectively studied. SUVmax, SUVmean, CoV, total Metabolic Tumor Volume (MTVTOT) and whole-body Total Lesion Glycolysis (TLGWB) were determined by an automated contouring program (SUV threshold at 2.5). We analyzed 194 lesions: primary tumors (n = 84), regional (n = 48) and non-regional (n = 17) lymph nodes and metastases in liver (n = 9), bone (n = 23) and other sites (n = 13); average CoVs were 0.36 ± 0.13, 0.36 ± 0.14, 0.42 ± 0.18, 0.30 ± 0.14, 0.37 ± 0.17, 0.34 ± 0.13, respectively. No significant differences were found between the CoV values among the different lesion categories. Survival analysis included age, gender, histology, stage, MTVTOT, TLGWB and imaging parameters derived from primary tumors. At univariate analysis, CoV (p = 0.0184), MTVTOT (p = 0.0050), TLGWB (p = 0.0108) and stage (p = 0.0041) predicted Overall Survival (OS). At multivariate analysis, age, CoV, MTVTOT and stage were retained in the model (p = 0.0001). Patients with CoV > 0.38 had significantly better OS than those with CoV ≤ 0.38 (p = 0.0143). Patients with MTVTOT ≤ 89.5 mL had higher OS than those with MTVTOT > 89.5 mL (p = 0.0063). Combining CoV and MTVTOT, patients with CoV ≤ 0.38 and MTVTOT > 89.5 mL had the worst prognosis. CoV, by reflecting the heterogeneity of glycolytic phenotype, can predict clinical outcomes in NSCLC patients.

What molecular imaging of cancer patients can teach us about COVID-19.

COVID-19 pandemic had a great impact on health systems and cancer care worldwide. Patients with cancer who develop COVID-19 are at high risk of severe outcomes and clarifying the determinants of such vulnerability of cancer patients would be of great clinical benefit. While the mechanisms of SARS-CoV-2 infection have been elucidated, the pathogenetic pathways leading to severe manifestations of the disease are largely unknown. Critical manifestations of COVID-19 mainly occur in elderly patients and in patients with serious comorbidities including cancer. Efforts to understand the intersection of pathways between severe manifestations of COVID-19 and cancer may shed light on the pathogenesis of critical illness in COVID-19 patients. Here, we will focus our attention on two major fields of potential intersection between COVID-19 and cancer, namely the dysfunction of immune system and the prothrombotic state that can occur in both COVID-19 and cancer patients, testing whether cancer imaging can provide clues to better understand such interactions.

Heterogeneity of SSTR2 Expression Assessed by 68Ga-DOTATOC PET/CT Using Coefficient of Variation in Patients with Neuroendocrine Tumors.

High levels of somatostatin receptor subtype 2 (SSTR2) are a prerequisite for therapy with unlabeled or labeled somatostatin analogs. However, it is still unclear how the heterogeneity of SSTR2 expression may affect tumor response to therapy. The aim of our study was to test the ability of an imaging parameter such as coefficient of variation (CoV) derived from PET/CT with 68Ga-peptides in the evaluation and quantification of the heterogeneity of SSTR2 expression within primary and metastatic lesions of patients with neuroendocrine tumors. Methods: Thirty-eight patients with pathologically proven neuroendocrine tumors who underwent 68Ga-DOTATOC PET/CT were studied. Primary tumors were localized in the gastroenteropancreatic, bronchopulmonary, and other anatomic districts in 25, 7, and 6 patients, respectively. Malignant lesions were segmented using an automated contouring program and an SUV threshold of more than 2.5 or, in the case of liver lesions, a threshold of 30% of the SUVmax The imaging parameters SUVmean, CoV, SUVmax, receptor-expressing tumor volume, and total lesion receptor expression were obtained for each lesion. SUVmean, CoV, and SUVmax were also obtained for representative volumes of normal liver and spleen, as well as for the whole pituitary gland. Results: In total, 107 lesions were analyzed, including 35 primary tumors, 32 metastatic lymph nodes, and 40 distant metastases. Average CoVs were 0.49 ± 0.20 for primary tumors, 0.57 ± 0.26 for lymph node metastases, and 0.44 ± 0.20 for distant metastases. The CoVs of malignant lesions were up to 4-fold higher than those of normal tissues (P ≤ 0.0001). Among malignant lesions, the highest CoV was found for bone metastases (0.68 ± 0.20), and it was significantly greater than that of primary lesions (P = 0.01) and liver metastases (P < 0.0001). On the other hand, the lowest CoV was found for liver lesions (0.32 ± 0.07), probably because of the high background uptake. Conclusion: Our findings indicate that the heterogeneity of uptake, reflecting that of SSTR2, varies with the type and site of malignant lesions as assessed by CoVs obtained from 68Ga-DOTATOC PET/CT scans. These observations may be related to different biologic characteristics of tumor lesions in the same patient-differences that may affect their response to treatment with both labeled and unlabeled somatostatin analogs.

Non-invasive detection of epithelial mesenchymal transition phenotype and metastatic dissemination of lung cancer by liquid biopsy.

The occurrence of phenotype switch from an epithelial to a mesenchymal cell state during the activation of the epithelial mesenchymal transition (EMT) program in cancer cells has been closely associated with the generation of invasive tumor cells that contribute to metastatic dissemination and treatment failure. Liquid biopsy represents an emergent non-invasive tool that may improve our understanding of the molecular events leading to cancer progression and initiating the metastatic cascade through the dynamic analysis of tumor-derived components isolated from body fluids. The present review will primarily focus on the applications of liquid biopsy in lung cancer patients for identifying EMT signature, elucidating molecular mechanisms underlying the acquisition of an invasive phenotype and detecting new targets for therapy.

PET-Based Volumetric Biomarkers for Risk Stratification of Non-Small Cell Lung Cancer Patients.

Despite the recent advances in lung cancer biology, molecular pathology, and treatment, this malignancy remains the leading cause of cancer-related death worldwide and non-small cell lung cancer (NSCLC) is the most common form found at diagnosis. Accurate staging of the disease is a fundamental prognostic factor that correctly predicts progression-free (PFS) and overall survival (OS) of NSCLC patients. However, outcome of patients within each TNM staging group can change widely highlighting the need to identify additional prognostic biomarkers to better stratify patients on the basis of risk. 18F-FDG PET/CT plays an essential role in staging, evaluation of treatment response, and tumoral target delineation in NSCLC patients. Moreover, a number of studies showed the prognostic role of imaging parameters derived from PET images, such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG). These parameters represent three-dimensional PET-based measurements providing information on both tumor volume and metabolic activity and previous studies reported their ability to predict OS and PFS of NSCLC patients. This review will primarily focus on the studies that showed the prognostic and predictive role of MTV and TLG in NSCLC patients, addressing also their potential utility in the new era of immunotherapy of NSCLC.

Non-Canonical Role of PDK1 as a Negative Regulator of Apoptosis through Macromolecular Complexes Assembly at the ER-Mitochondria Interface in Oncogene-Driven NSCLC.

Here, we tested whether co-targeting of glucose metabolism and oncogene drivers may enhance tumor response to tyrosine kinase inhibitors (TKIs) in NSCLC. To this end, pyruvate dehydrogenase kinase 1 (PDK1) was stably downregulated in oncogene-driven NSCLC cell lines exposed or not to TKIs. H1993 and H1975 cells were stably transfected with scrambled (shCTRL) or PDK1-targeted (shPDK1) shRNA and then treated with MET inhibitor crizotinib (1 µM), double mutant EGFRL858R/T790M inhibitor WZ4002 (1 µM) or vehicle for 48 h. The effects of PDK1 knockdown on glucose metabolism and apoptosis were evaluated in untreated and TKI-treated cells. PDK1 knockdown alone did not cause significant changes in glycolytic cascade, ATP production and glucose consumption, but it enhanced maximal respiration in shPDK1 cells when compared to controls. When combined with TKI treatment, PDK1 downregulation caused a strong enhancement of OXPHOS and a marked reduction in key glycolytic enzymes. Furthermore, increased levels of apoptotic markers were found in shPDK1 cells as compared to shCTRL cells after treatment with TKIs. Co-immunoprecipitation studies showed that PDK1 interacts with PKM2, Bcl-2 and Bcl-xL, forming macromolecular complexes at the ER-mitochondria interface. Our findings showed that downregulation of PDK1 is able to potentiate the effects of TKIs through the disruption of macromolecular complexes involving PKM2, Bcl-2 and Bcl-xL.

A Reversible Shift of Driver Dependence from EGFR to Notch1 in Non-Small Cell Lung Cancer as a Cause of Resistance to Tyrosine Kinase Inhibitors.

Notch1 plays a key role in epithelial-mesenchymal transition (EMT) and in the maintenance of cancer stem cells. In the present study we tested whether high levels of activated Notch1 in oncogene-driven NSCLC can induce a reversible shift of driver dependence from EGFR to Notch1, and thus causing resistance to EGFR inhibitors. Adherent cells (parental) and tumor spheres (TS) from NSCLC H1975 cells and patient-derived CD133-positive cells were tested for EGFR and Notch1 signaling cascade. The Notch1-dependent modulation of EGFR, NCID, Hes1, p53, and Sp1 were then analyzed in parental cells by binding assays with a Notch1 agonist, DLL4. TS were more resistant than parental cells to EGFR inhibitors. A strong upregulation of Notch1 and a concomitant downregulation of EGFR were observed in TS compared to parental cells. Parental cell exposure to DLL4 showed a dose-dependent decrease of EGFR and a simultaneous increase of NCID, Hes1, p53, and Sp1, along with the dislocation of Sp1 from the EGFR promoter. Furthermore, an enhanced interaction between p53 and Sp1 was observed in TS. In NSCLC cells, high levels of active Notch1 can promote a reversible shift of driver dependence from EGFR to Notch1, leading to resistance to EGFR inhibitors.

Brain Metastases Unresponsive to Immunotherapy Detected by 18F-FDG-PET/CT in a Patient with Melanoma.

Recently, newer therapies such as immunotherapy have been increasingly used in the treatment of several tumors, including advanced melanoma. In particular, several studies showed that the combination of ipilimumab, an anti-Cytotoxic T-lymphocyte Associated Protein 4 (CTLA-4) monoclonal antibody and nivolumab, an anti-Programmed Death 1 (PD-1) monoclonal antibody, leads to improved survival in patients with metastatic melanoma. Despite that, immunotherapeutic agents may not reach therapeutic concentration in the brain due to the blood-brain barrier. We report the case of a 50-year-old man with advanced melanoma who underwent whole-body 18F-FDG-PET/CT before and after treatment with immunotherapy showing resistant brain metastases confirmed by subsequent MRI of the brain. Moreover, 18F-FDG-PET/CT was able to detect an immune-related adverse event such as enterocolitis that contributed to the worsening of patient conditions. This case shows how a whole-body methodology such as 18F-FDG-PET/CT can be useful in identifying melanoma cancer patients unresponsive to immunotherapy that may benefit from traditional palliative therapy in the effort to improve their quality of life.