Metabolic characteristics of programmed cell death-ligand 1-expressing lung cancer on 18 F-fluorodeoxyglucose positron emission tomography/computed tomography

Clinical feasibility study of early 30-minute dynamic FDG-PET scanning protocol for patients with lung lesions

PURPOSE

This study aimed to evaluate the clinical feasibility of early 30-minute dynamic 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG) positron emission tomography (PET) scanning protocol for patients with lung lesions in comparison to the standard 65-minute dynamic FDG-PET scanning as a reference.

METHODS

Dynamic 18F-FDG PET images of 146 patients with 181 lung lesions (including 146 lesions confirmed by histology) were analyzed in this prospective study. Dynamic images were reconstructed into 28 frames with a specific temporal division protocol for the scan data acquired 65 min post-injection. Ki images and quantitative parameters Ki based on two different acquisition durations [the first 30 min (Ki-30 min) and 65 min (Ki-65 min)] were obtained by applying the irreversible two-tissue compartment model using in-house Matlab software. The two acquisition durations were compared for Ki image quality (including visual score analysis and number of lesions detected) and Ki value (including accuracy of Ki, the value of differential diagnosis of lung lesions and prediction of PD-L1 status) by Wilcoxon's rank sum test, Spearman's rank correlation analysis, receiver operating characteristic (ROC) curve, and the DeLong test. The significant testing level (alpha) was set to 0.05.

RESULTS

The quality of the Ki-30 min images was not significantly different from the Ki-65 min images based on visual score analysis (P > 0.05). In terms of Ki value, among 181 lesions, Ki-65 min was statistically higher than Ki-30 min (0.027 ± 0.017 ml/g/min vs. 0.026 ± 0.018 ml/g/min, P < 0.05), while a very high correlation was obtained between Ki-65 min and Ki-30 min (r = 0.977, P < 0.05). In the differential diagnosis of lung lesions, ROC analysis was performed on 146 histologically confirmed lesions, the area under the curve (AUC) of Ki-65 min, Ki-30 min, and SUVmax was 0.816, 0.816, and 0.709, respectively. According to the Delong test, no significant differences in the diagnostic accuracies were found between Ki-65 min and Ki-30 min (P > 0.05), while the diagnostic accuracies of Ki-65 min and Ki-30 min were both significantly higher than that of SUVmax (P < 0.05). In 73 (NSCLC) lesions with definite PD-L1 expression results, the Ki-65 min, Ki-30 min, and SUVmax in PD-L1 positivity were significantly higher than that in PD-L1 negativity (P < 0.05). And no significant differences in predicting PD-L1 positivity were found among Ki-65 min, Ki-30 min, and SUVmax (AUC = 0.704, 0.695, and 0.737, respectively, P > 0.05), according to the results of ROC analysis and Delong test.

CONCLUSIONS

This study indicates that an early 30-minute dynamic FDG-PET acquisition appears to be sufficient to provide quantitative images with good-quality and accurate Ki values for the assessment of lung lesions and prediction of PD-L1 expression. Protocols with a shortened early 30-minute acquisition time may be considered for patients who have difficulty with prolonged acquisitions to improve the efficiency of clinical acquisitions.

Predicting programmed death-ligand 1 (PD-L1) expression with fluorine-18 fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) metabolic parameters in resectable non-small cell lung cancer

BACKGROUND

Programmed death-ligand 1 (PD-L1) expression is a predictive biomarker for immunotherapy in non-small cell lung cancer (NSCLC). PD-L1 and glucose transporter 1 expression are closely associated, and studies demonstrate correlation of PD-L1 with glucose metabolism.

AIM

The aim of this study was to investigate the association of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG-PET/CT) metabolic parameters with PD-L1 expression in primary lung tumour and lymph node metastases in resected NSCLC.

METHODS

We conducted a retrospective analysis of 210 patients with node-positive resectable stage IIB-IIIB NSCLC. PD-L1 tumour proportion score (TPS) was determined using the DAKO 22C3 immunohistochemical assay. Semi-automated techniques were used to analyse pre-operative [18F]FDG-PET/CT images to determine primary and nodal metabolic parameter scores (including max, mean, peak and peak adjusted for lean body mass standardised uptake values (SUV), metabolic tumour volume (MTV), total lesional glycolysis (TLG) and SUV heterogeneity index (HISUV)).

RESULTS

Patients were predominantly male (57%), median age 70 years with non-squamous NSCLC (68%). A majority had negative primary tumour PD-L1 (TPS < 1%; 53%). Mean SUVmax, SUVmean, SUVpeak and SULpeak values were significantly higher (p < 0.05) in those with TPS ≥ 1% in primary tumour (n = 210) or lymph nodes (n = 91). However, ROC analysis demonstrated only moderate separability at the 1% PD-L1 TPS threshold (AUCs 0.58-0.73). There was no association of MTV, TLG and HISUV with PD-L1 TPS.

CONCLUSION

This study demonstrated the association of SUV-based [18F]FDG-PET/CT metabolic parameters with PD-L1 expression in primary tumour or lymph node metastasis in resectable NSCLC, but with poor sensitivity and specificity for predicting PD-L1 positivity ≥ 1%.

CLINICAL RELEVANCE STATEMENT

Whilst SUV-based fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography metabolic parameters may not predict programmed death-ligand 1 positivity ≥ 1% in the primary tumour and lymph nodes of resectable non-small cell lung cancer independently, there is a clear association which warrants further investigation in prospective studies.

TRIAL REGISTRATION

Non-applicable KEY POINTS: • Programmed death-ligand 1 immunohistochemistry has a predictive role in non-small cell lung cancer immunotherapy; however, it is both heterogenous and dynamic. • SUV-based fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG-PET/CT) metabolic parameters were significantly higher in primary tumour or lymph node metastases with positive programmed death-ligand 1 expression. • These SUV-based parameters could potentially play an additive role along with other multi-modal biomarkers in selecting patients within a predictive nomogram.

Opportunities and challenges in combining immunotherapy and radiotherapy in esophageal cancer

BACKGROUND

Immunotherapy has shown promise in the treatment of esophageal cancer, but using it alone only benefits a small number of patients. Most patients either do not have a significant response or develop secondary drug resistance. The combination of radiotherapy and immunotherapy appears to be a promising approach to treating esophageal cancer.

PURPOSE

We reviewed milestone clinical trials of radiotherapy combined with immunotherapy for esophageal cancer. We then discussed potential biomarkers for radiotherapy combined with immunotherapy, including programmed cell death-ligand 1 (PD-L1) status, tumor mutation burden (TMB), tumor-infiltrating lymphocytes, ct-DNA, imaging biomarkers, and clinical factors. Furthermore, we emphasize the key mechanisms of radiation therapy-induced immune stimulation and immune suppression in order to propose strategies for overcoming immune resistance in radiation therapy (RT). Lastly, we discussed the emerging role of low-dose radiotherapy (LDRT) , which has become a promising approach to overcome the limitations of high-dose radiotherapy.

CONCLUSION

Radiotherapy can be considered a triggering factor for systemic anti-tumor immune response and, with the assistance of immunotherapy, can serve as a systemic treatment option and potentially become the standard treatment for cancer patients.

18 F-FDG PET/CT for evaluation of metastases in nonsmall cell lung cancer on the efficacy of immunotherapy

OBJECTIVE

This study aimed to investigate the relationship between 18 F-fluorodeoxyglucose PET/computed tomography ( 18 F-FDG PET/CT) metabolic parameters and clinical benefit and prognosis in nonsmall cell lung cancer (NSCLC).

METHODS

In total, 34 advanced NSCLC patients who received 18 F-FDG PET/CT before immunotherapy were retrospectively included in this study. All patients were divided into two groups, the clinical benefit (CB) group and the no-clinical benefit (no-CB) group, based on the efficacy of evaluation after 6 months of treatment. Also clinical information, characteristics of metastases, survival, PD-L1 expression level and glucose metabolic parameters were evaluated.

RESULTS

Finally, 24 patients were in the CB group, and 10 patients were in the no-CB group. There was a significant difference between the CB group and the no-CB group in TNM stages ( P  = 0.005), visceral and bone metastasis ( P  = 0.031), metabolic tumor volume of primary lesion (MTV-P; P  = 0.003), the metabolic tumor volume of whole-body (MTVwb; P  = 0.005) and total lesion glycolysis of whole-body (TLGwb, P  = 0.015). However, for patient outcomes, the independent prognostic factors associated with progression free survival were TNM stage (HR = 0.113; 95% CI, 0.029-0.439; P  = 0.002), TLG-P (HR = 0.085; 95% CI, 0.018-0.402; P  = 0.002) and TLG-LN (HR = 0.068; 95% CI, 0.015-0.308; P  = 0.000), and the TLG-LN (HR = 0.242; 95% CI, 0.066-0.879; P  = 0.002) was the independent prognostic factor associated with overall survival.

CONCLUSIONS

Metastatic lesion burden evaluated by 18 F-FDG PET/ CT can predict response to immunotherapy in advanced NSCLC patients, in which lymph node metastasis lesion metabolic burden is a meaningful predictor, but a large multicenter trial is still needed to validate this conclusion.

Prognostic value of 18F-FDG PET/CT in patients with advanced or metastatic non-small-cell lung cancer treated with immune checkpoint inhibitors: A systematic review and meta-analysis

PURPOSE

This study aimed to investigate the value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in predicting early immunotherapy response of immune checkpoint inhibitors (ICIs) in patients with advanced or metastatic non-small-cell lung cancer (NSCLC).

METHODS

A comprehensive search of PubMed, Web of science, Embase and the Cochrane library was performed to examine the prognostic value of 18F-FDG PET/CT in predicting early immunotherapy response of ICIs in patients with NSCLC. The main outcomes for evaluation were overall survival (OS) and progression-free survival (PFS). Detailed data from each study were extracted and analyzed using STATA 14.0 software.

RESULTS

13 eligible articles were included in this systematic review. Compared to baseline 18F-FDG PET/CT imaging, the pooled hazard ratios (HR) of maximum and mean standardized uptake values SUVmax, SUVmean, MTV and TLG for OS were 0.88 (95% CI: 0.69-1.12), 0.79 (95% CI: 0.50-1.27), 2.10 (95% CI: 1.57-2.82) and 1.58 (95% CI: 1.03-2.44), respectively. The pooled HR of SUVmax, SUVmean, MTV and TLG for PFS were 1.06 (95% CI: 0.68-1.65), 0.66 (95% CI: 0.48-0.90), 1.50 (95% CI: 1.26-1.79), 1.27 (95% CI: 0.92-1.77), respectively. Subgroup analysis showed that high MTV group had shorter OS than low MTV group in both first line group (HR: 1.97, 95% CI: 1.39-2.79) and undefined line group (HR: 2.11, 95% CI: 1.61-2.77). High MTV group also showed a shorter PFS in first line group (HR: 1.85, 95% CI: 1.28-2.68), and low TLG group had a longer OS in undefined group (HR: 1.37, 95% CI: 1.00-1.86). No significant differences were in other subgroup analysis.

CONCLUSION

Baseline MTV and TLG may have predictive value and should be prospectively studied in clinical trials. Baseline SUVmax and SUVmean may not be appropriate prognostic markers in advanced or metastatic NSCLC patients treated with ICIs.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=323906, identifier CRD42022323906.

FDG PET and CT radiomics in diagnosis and prognosis of non-small-cell lung cancer

BACKGROUND

18F-FDG PET and CT radiomics has been the object of a wide research for over 20 years but its contribution to clinical practice remains not yet well established. We have investigated its impact versus that of only histo-clinical data, for the routine management of non-small-cell lung cancer (NSCLC).

METHODS

Our patients were retrospectively considered. They all had a FDG PET-CT and immuno-histo-chemistry (IHC) to assess PD-L1 expression at the beginning of the disease. A prognosis univariate and multivariate Cox survival analyses was performed for overall survival (OS) and progression free survival (PFS) prediction, including a training/testing procedure. Two sets of 47 PET and 47 CT radiomics features (RFs) were extracted. Difference between RFs according to PD-L1 expression, the histology status and the stage level were tested using suited non parametric statistical tests and the receiver operating characteristics (ROC) curve and the area under curve (AUC).

RESULTS

From 2017 to 2019, 212 NSCLC patients treated in our institution were included. The main conventional prognostic variables were stage and gender with a low added prognostic value in the models including PET and CT RFs. Neither PET nor CT RFs were significant to separate the different levels of PD-L1 expression. Several RFs differ between adenocarcinoma (ADC) and squamous cell carcinoma (SCC) tumours and a large number of PET and CT RFs are significantly linked to patient stage.

CONCLUSIONS

In our population, PET and CT RFs show their intrinsic power to predict survival but do not significantly improve OS and PFS prediction in the different multivariate models, in comparison to conventional data. It would seem necessary to carry out one's own survival analysis before determining a radiomics signature.

The predictive value of total-body PET/CT in non-small cell lung cancer for the PD-L1 high expression

Purpose

Total-body positron emission tomography/computed tomography (PET/CT) provides faster scanning speed, higher image quality, and lower injected dose. To compensate for the shortcomings of the maximum standard uptake value (SUVmax), we aimed to normalize the values of PET parameters using liver and blood pool SUV (SUR-L and SUR-BP) to predict programmed cell death-ligand 1 (PD-L1) expression in non-small cell lung cancer (NSCLC) patients.

Materials and methods

A total of 138 (104 adenocarcinoma and 34 squamous cell carcinoma) primary diagnosed NSCLC patients who underwent ¹⁸F-FDG-PET/CT imaging were analyzed retrospectively. Immunohistochemistry (IHC) analysis was performed for PD-L1 expression on tumor cells and tumor-infiltrating immune cells with 22C3 antibody. Positive PD-L1 expression was defined as tumor cells no less than 50% or tumor-infiltrating immune cells no less than 10%. The relationships between PD-L1 expression and PET parameters (SUVmax, SUR-L, and SUR-BP) and clinical variables were analyzed. Statistical analysis included χ² test, receiver operating characteristic (ROC), and binary logistic regression.

Results

There were 36 patients (26%) expressing PD-L1 positively. Gender, smoking history, Ki-67, and histologic subtype were related factors. SUVmax, SUR-L, and SUR-BP were significantly higher in the positive subset than those in the negative subset. Among them, the area under the curve (AUC) of SUR-L on the ROC curve was the biggest one. In NSCLC patients, the best cutoff value of SUR-L for PD-L1-positive expression was 4.84 (AUC = 0.702, P = 0.000, sensitivity = 83.3%, specificity = 54.9%). Multivariate analysis confirmed that age and SUR-L were correlated factors in adenocarcinoma (ADC) patients.

Conclusion

SUVmax, SUR-L, and SUR-BP had utility in predicting PD-L1 high expression, and SUR-L was the most reliable parameter. PET/CT can offer reference to screen patients for first-line atezolizumab therapy.

Predictive value of baseline metabolic tumor volume for non-small-cell lung cancer patients treated with immune checkpoint inhibitors: A meta-analysis

Background

Immune checkpoint inhibitors (ICIs) have emerged as a promising treatment option for advanced non-small-cell lung cancer (NSCLC) patients, highlighting the need for biomarkers to identify responders and predict the outcome of ICIs. The purpose of this study was to evaluate the predictive value of baseline standardized uptake value (SUV), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) derived from 18F-FDG-PET/CT in advanced NSCLC patients receiving ICIs.

Methods

PubMed and Web of Science databases were searched from January 1st, 2011 to July 18th, 2022, utilizing the search terms “non-small-cell lung cancer”, “PET/CT”, “standardized uptake value”, “metabolic tumor volume”, “ total lesion glycolysis”, and “immune checkpoint inhibitors”. Studies that analyzed the association between PET/CT parameters and objective response, immune-related adverse events (irAEs) and prognosis of NSCLC patients treated with ICIs were included. We extracted the hazard ratio (HR) with a 95% confidence interval (CI) for progression-free survival (PFS) and overall survival (OS). We performed a meta-analysis of HR using Review Manager v.5.4.1.

Results

Sixteen studies were included for review and thirteen for meta-analysis covering 770 patients. As for objective response and irAEs after ICIs, more studies with consistent assessment methods are needed to determine their relationship with MTV. In the meta-analysis, low SUVmax corresponded to poor PFS with a pooled HR of 0.74 (95% CI, 0.57-0.96, P=0.02). And a high level of baseline MTV level was related to shorter PFS (HR=1.45, 95% CI, 1.11-1.89, P<0.01) and OS (HR, 2.72; 95% CI, 1.97-3.73, P<0.01) especially when the cut-off value was set between 50-100 cm³. SUVmean and TLG were not associated with the prognosis of NSCLC patients receiving ICIs.

Conclusions

High level of baseline MTV corresponded to shorter PFS and OS, especially when the cut-off value was set between 50-100 cm³. MTV is a potential predictive value for the outcome of ICIs in NSCLC patients.

Dynamic 18 F-FDG PET/CT can predict the major pathological response to neoadjuvant immunotherapy in non-small cell lung cancer

Major pathological response (MPR) is a potential surrogate for overall survival. We determined whether the dynamic changes in ¹⁸ F-labeled fluoro-2-deoxyglucose positron emission tomography/computed tomography (¹⁸ F-FDG PET/CT) were associated with MPR in patients receiving neoadjuvant immunotherapy. Forty-four patients with stage II-III non-small cell lung cancer (NSCLC) who received neoadjuvant immunotherapy and radical surgery were enrolled. Moreover, ¹⁸ F-FDG PET/CT scans were performed at baseline and within 1 week before surgery to evaluate the disease. All histological sections were reviewed to assess MPR. The detailed clinical features of the patients were analyzed. The reliability of the clinical variables was assessed in differentiating between MPR and non-MPR using logistic regression. Receiver-operating characteristic (ROC) curve analysis identified the SUVmax changes threshold most associated with MPR. Most of the patients were pathologically diagnosed with squamous cell carcinoma and received anti-PD-1 antibodies plus chemotherapy. The immunotherapy regimens included nivolumab, pembrolizumab, and camrelizumab. MPR was observed in more than half of lesions. Tumors with MPR had a higher decrease in the longest dimension on dynamic PET/CT than those without MPR. Furthermore, the decline in SUVmax was significantly different between MPR and non-MPR diseases, and MPR lesions had a prominent mean reduction in SUVmax. SUVmax reduction was independently associated with MPR in the multivariate regression. On ROC analysis, the threshold of SUVmax decrease in 60% was associated with MPR. Dynamic changes in SUVmax were associated with MPR. The tumors with MPR showed a greater PET/CT response than those without MPR. A SUVmax decrease of more than 60% is more likely to result in an MPR after receiving neoadjuvant immunotherapy.

Monitoring of Current Cancer Therapy by Positron Emission Tomography and Possible Role of Radiomics Assessment

Evaluation of cancer therapy with imaging is crucial as a surrogate marker of effectiveness and survival. The unique response patterns to therapy with immune-checkpoint inhibitors have facilitated the revision of response evaluation criteria using FDG-PET, because the immune response recalls reactive cells such as activated T-cells and macrophages, which show increased glucose metabolism and apparent progression on morphological imaging. Cellular metabolism and function are critical determinants of the viability of active cells in the tumor microenvironment, which would be novel targets of therapies, such as tumor immunity, metabolism, and genetic mutation. Considering tumor heterogeneity and variation in therapy response specific to the mechanisms of therapy, appropriate response evaluation is required. Radiomics approaches, which combine objective image features with a machine learning algorithm as well as pathologic and genetic data, have remarkably progressed over the past decade, and PET radiomics has increased quality and reliability based on the prosperous publications and standardization initiatives. PET and multimodal imaging will play a definitive role in personalized therapeutic strategies by the precise monitoring in future cancer therapy.

Prognostic Potential of Metabolic Activity on 18F-FDG Accumulation in Advanced NSCLC Receiving Combining Chemotherapy Plus PD-1 Blockade

Combined chemotherapy plus programmed death-1 (PD-1) blockade is an established treatment against patients with advanced non-small cell lung cancer (NSCLC). However, a promising predictor besides programmed death ligand-1 expression remains uncertain. We examined the prognostic significance of baseline 18F-FDG-positron emission tomography for predicting first-line combined chemotherapy plus PD-1 blockade in NSCLC patients. Forty-five patients with advanced NSCLC who received 18F-FDG-positron emission tomography immediately before combined platinum-based chemotherapy with PD-1 blockade as first-line setting were eligible for this study, and assessment of maximum of standard uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) on 18F-FDG uptake was performed. The objective response rate, median progression-free survival, and overall survival were 51.2%, 206 days, and 681 days, respectively. High SUVmax, TLG, and MTV significantly correlated with age and performance status (PS), C-reactive protein (CRP), and PS, CRP, albumin, and baseline tumor size, respectively. Univariate analysis identified albumin, TLG and MTV as significant predictors of progression-free survival, and CRP, albumin, TLG and MTV as significant factors for predicting overall survival. High TLG was confirmed as an independent factor associated with poor prognosis in multivariate analysis. In particular, TLG is identified as the most powerful predictor in patients with good PS, adenocarcinoma, programmed death ligand-1≥1%, and low baseline tumor size. The tumor metabolic volume by MTV and TLG at pretreatment was clarified as a significant predictor for combined chemotherapy with PD-1 blockade, but not maximal glycolytic level by SUVmax.

18F FDG PET/CT and Novel Molecular Imaging for Directing Immunotherapy in Cancer

Immunotherapy has transformed the treatment landscape of many cancers, with durable responses in disease previously associated with a poor prognosis. Patient selection remains a challenge, with predictive biomarkers an urgent unmet clinical need. Current predictive biomarkers, including programmed death-ligand 1 (PD-L1) (measured with immunohistochemistry), are imperfect. Promising biomarkers, including tumor mutation burden and tumor infiltrating lymphocyte density, fail to consistently predict response and have yet to translate to routine clinical practice. Heterogeneity of immune response within and between lesions presents a further challenge where fluorine 18 fluorodeoxyglucose PET/CT has a potential role in assessing response, stratifying treatment, and detecting and monitoring immune-related toxicities. Novel radiopharmaceuticals also present a unique opportunity to define the immune tumor microenvironment to better predict which patients may respond to therapy, for example by means of in vivo whole-body PD-L1 and CD8+ T cell expression imaging. In addition, longitudinal molecular imaging may help further define dynamic changes, particularly in cases of immunotherapy resistance, helping to direct a more personalized therapeutic approach. This review highlights current and emerging applications of molecular imaging to stratify, predict, and monitor molecular dynamics and treatment response in areas of clinical need.

Prospective assessment using 18F-FDG PET/CT as a novel predictor for early response to PD-1 blockade in non-small-cell lung cancer

Anti-programmed death-1 (PD-1) blockade is a standard treatment for advanced non-small-cell lung cancer (NSCLC). However, no appropriate modality exists for monitoring its therapeutic response immediately after initiation. Therefore, we aimed to elucidate the clinical relevance of ¹⁸F-FDG PET/CT versus CT in predicting the response to PD-1 blockade in the early phase. This prospective study included a total of 54 NSCLC patients. ¹⁸F-FDG PET/CT was performed at 4 weeks and 9 weeks after PD-1 blockade monotherapy. Maximum standardized uptake values (SUL_max), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were evaluated. Among all patients, partial metabolic response and progressive metabolic disease after PD-1 blockade were observed in 35.2% and 11.1% on SUL_max, 22.2% and 51.8% on MTV, and 27.8% and 46.3% on TLG, respectively, whereas a partial response (PR) and progressive disease (PD), respectively, based on RECIST v1.1 were recognized in 35.2% and 35.2%, respectively. The predictive probability of PR (MTV: 57.9% vs. 21.1%, p = 0.044; TLG: 63.2% vs. 21.1%, p = 0.020) and PD (MTV: 78.9% vs. 47.3%, p = 0.002; TLG: 73.7% vs. 21.1%, p = 0.007) detected based on RECIST at 4 weeks after PD-1 blockade initiation was significantly higher using MTV or TLG on ¹⁸F-FDG uptake than on CT. Multivariate analysis revealed that metabolic response by MTV or TLG at 4 weeks was an independent factor for response to PD-1 blockade treatment. Metabolic assessment by MTV or TLG was superior to morphological changes on CT for predicting the therapeutic response and survival at 4 weeks after PD-1 blockade.

Application of molecular imaging in immune checkpoints therapy: From response assessment to prognosis prediction

Recently, immune checkpoint therapy (ICT) represented by programmed cell death1 (PD-1) and its major ligands, programmed death ligand 1 (PD-L1), has achieved significant success. Detection of PD-L1 by immunohistochemistry (IHC) is a classic method to guide the treatment of ICT patients. However, PD-L1 expression in the tumor microenvironment is highly complex. Thus, PD-L1 IHC is inadequate to fully understand the relevance of PD-L1 levels in the whole body and their dynamics to improve therapeutic outcomes. Intriguingly, numerous studies have revealed that molecular imaging technologies could potentially meet this need. Therefore, the purpose of this narrative review is to summarize the preclinical and clinical application of ICT guided by molecular imaging technology, and to explore the future opportunities and practical difficulties of these innovations.

Prognostic Significance of PD-L1 Expression and Standardized Uptake Values in the Primary Lesions of Stage IV Adenocarcinoma Lung Cancer

Background

This study evaluated the prognostic ability of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) in patients with stage IV adenocarcinoma lung cancer to detect protein death-ligand 1 (PD-L1) expression levels.

Methods

In total, 86 patients with stage IV adenocarcinoma lung cancer underwent ¹⁸F-FDG PET/CT imaging and PD-L1 expression evaluation before treatment from February 2019 to November 2020 at Bach Mai Hospital, Hanoi, Vietnam. The assessed patient characteristics in this study included sex, age, smoking status, epidermal growth factor receptor (EGFR) mutation, PD-L1 expression level, survival status, tumor, node, and metastasis (TNM) stage, and metastasis locations.

Results

The average age was 62.23 ± 9.51 years, and men and women represented 67.4% and 32.6% of the population, respectively. The EGFR mutation rate was 36%. PD-L1 expression was negative (detected in <1% of the tumor) in 40.7% of cases and positive in 59.3% of cases (detected in 1–49% of the tumor in 32.6%; detected in ≥50% of the tumor in 26.7%). The mean maximum standardized uptake value (SUV_max) was 11.09 ± 3.94. SUV_max was significantly higher in PD-L1–positive tumors than in PD-L1–negative tumors (12.24 ± 4.01 and 9.43 ± 3.22, respectively; p = 0.001). Receiver operating characteristic curve analysis revealed an area under the curve of SUVmax was 0.681 (95% confidence interval 0.570–0.793, p = 0.004). Compared with PD-L1–negative cases, SUV_max was significantly different in all PD-L1–positive cases (p = 0.001), weakly PD-L1–positive cases (1–49%, p = 0.005), and strongly PD-L1–positive cases (≥50%, p = 0.003). PD-L1 expression levels were significantly associated with SUV_max (p = 0.001), tumor size (p = 0.022), and EGFR mutation status (p = 0.045).

Conclusions

SUV_max in the primary lesions was able to predict PD-L1 expression and may play a role in predicting PD-L1 immunotherapy efficacy in patients with stage IV lung adenocarcinoma.

Correlation of epidermal growth factor receptor mutation status and PD-L1 expression with [18F]FDG PET using volume-based parameters in non-small cell lung cancer

OBJECTIVE

We investigated the relationship between 2-deoxy-2-[18F]fluoro-D-glucose (FDG) PET using volume-based parameters and epidermal growth factor receptor (EGFR) mutation status, programmed death-ligand-1 (PD-L1) expression level, and their combination, in pretreated non-small cell lung cancer (NSCLC).

METHODS

FDG PET findings and EGFR mutation status and PD-L1 expression level were investigated retrospectively in 93 patients with newly diagnosed NSCLC (77 adenocarcinomas, 16 squamous cell carcinomas). Tumors were divided into six groups: EGFR mutant/negative PD-L1, EGFR mutant/low PD-L1, EGFR mutant/high PD-L1, EGFR wild/negative PD-L1, EGFR wild/low PD-L1, and EGFR wild/high PD-L1. The maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for primary tumor were measured from PET images. The EGFR mutation status and PD-L1 expression level were estimated in tumor tissue specimens and compared with the PET parameters.

RESULTS

None of the PET parameters differed significantly between EGFR-mutated and wild-type EGFR. According to the PD-L1 level, significant differences were detected in SUVmax (P = 0.001) and TLG (P = 0.016), but not MTV. Comparing all six groups, significant difference was detected in only SUVmax (P = 0.011).

CONCLUSION

Based on the preliminary results of this study, FDG PET may help in the prediction of PD-L1 expression level, but not EGFR mutation status, in patients with newly diagnosed NSCLC. The SUVmax rather than MTV or TLG, may be of value in predicting the six groups according to the combination of EGFR mutation status and PD-L1 expression level.

Visual Assessment of 18F-FDG Uptake on PET to Predict Survival Benefit to PD-1 Blockade in Non-Small Cell Lung Cancer

BACKGROUND

Programmed death 1 (PD-1) blockade is a standard treatment for patients with metastatic non-small cell lung cancer (NSCLC). Approximately 20% patients receiving PD-1 blockade monotherapy can survive for more than 5 years. However, there are limited data on the optimal biomarkers for predicting long-term outcomes. Therefore, this study aimed to evaluate the prognostic significance of 18F-FDG uptake in patients with NSCLC responding to PD-1 blockade.

PATIENTS AND METHODS

Thirty-eight patients with advanced NSCLC who underwent 18F-FDG PET after confirmation of clinical response to PD-1 blockade monotherapy were retrospectively included in this study. Visual assessment using a 5-point scale score according to 18F-FDG uptake was performed, and the 18F-FDG uptake cutoff score for prolonged response to PD-1 blockade was defined as 3 (low score: 1, 2, or 3 and high score: 4 or 5).

RESULTS

A significantly greater number of patients with low scores had a performance status of 0 or 1 than patients with high scores. Among the 38 patients, 20 (53%) had a low score and 18 (47%) had a high score. Progression-free survival and overall survival were significantly longer in patients with low scores than in patients with high scores. Low 18F-FDG uptake was an independent prognostic factor for predicting favorable progression-free survival and overall survival, as confirmed by multivariate analysis.

CONCLUSIONS

Tumors with lower 18F-FDG uptake on PET than normal hepatic lesions exhibit the possibility of prolonged response to PD-1 blockade. Visual assessment on PET is easy for every clinician and is understandable to confirm aggressive tumor activity.

Imaging the Rewired Metabolism in Lung Cancer in Relation to Immune Therapy

Metabolic reprogramming is recognized as one of the hallmarks of cancer. Alterations in the micro-environmental metabolic characteristics are recognized as important tools for cancer cells to interact with the resident and infiltrating T-cells within this tumor microenvironment. Cancer-induced metabolic changes in the micro-environment also affect treatment outcomes. In particular, immune therapy efficacy might be blunted because of somatic mutation-driven metabolic determinants of lung cancer such as acidity and oxygenation status. Based on these observations, new onco-immunological treatment strategies increasingly include drugs that interfere with metabolic pathways that consequently affect the composition of the lung cancer tumor microenvironment (TME). Positron emission tomography (PET) imaging has developed a wide array of tracers targeting metabolic pathways, originally intended to improve cancer detection and staging. Paralleling the developments in understanding metabolic reprogramming in cancer cells, as well as its effects on stromal, immune, and endothelial cells, a wave of studies with additional imaging tracers has been published. These tracers are yet underexploited in the perspective of immune therapy. In this review, we provide an overview of currently available PET tracers for clinical studies and discuss their potential roles in the development of effective immune therapeutic strategies, with a focus on lung cancer. We report on ongoing efforts that include PET/CT to understand the outcomes of interactions between cancer cells and T-cells in the lung cancer microenvironment, and we identify areas of research which are yet unchartered. Thereby, we aim to provide a starting point for molecular imaging driven studies to understand and exploit metabolic features of lung cancer to optimize immune therapy.

Pseudoprogression in lung cancer patients treated with immunotherapy

Lung cancer has attracted much attention because of its high morbidity and mortality worldwide. The advent of immunotherapy approaches, especially the application of immune checkpoint inhibitors (ICIs) has dramatically changed the treatment of lung cancer, but a novel and unexpected pattern of treatment response-- pseudoprogression, has been observed simultaneously which complicates the routine clinical evaluation and management. However, manifestations of pseudoprogression vary and there are many disputes on immune-related response assessment and corresponding treatments for lung cancer. Therefore, we summarized the possible mechanisms, clinical manifestations and corresponding treatment measures of pseudoprogression in lung cancer, as well as potential methods to differentiate pseudoprogression from true tumor progression.

Immunotherapy Monitoring with Immune Checkpoint Inhibitors Based on [18F]FDG PET/CT in Metastatic Melanomas and Lung Cancer

Immunotherapy with checkpoint inhibitors has prompted a major change not only in cancer treatment but also in medical imaging. In parallel with the implementation of new drugs modulating the immune system, new response criteria have been developed, aiming to overcome clinical drawbacks related to the new, unusual, patterns of response characterizing both solid tumors and lymphoma during the course of immunotherapy. The acknowledgement of pseudo-progression, hyper-progression, immune-dissociated response and so forth, has become mandatory for all imagers dealing with this clinical scenario. A long list of acronyms, i.e., irRC, iRECIST, irRECIST, imRECIST, PECRIT, PERCIMT, imPERCIST, iPERCIST, depicts the enormous effort made by radiology and nuclear medicine physicians in the last decade to optimize imaging parameters for better prediction of clinical benefit in immunotherapy regimens. Quite frequently, a combination of clinical-laboratory data with imaging findings has been tested, proving the ability to stratify patients into various risk groups. The next steps necessarily require a large scale validation of the most robust criteria, as well as the clinical implementation of immune-targeting tracers for immuno-PET or the exploitation of radiomics and artificial intelligence as complementary tools during the course of immunotherapy administration. For the present review article, a summary of PET/CT role for immunotherapy monitoring will be provided. By scrolling into various cancer types and applied response criteria, the reader will obtain necessary information for better understanding the potentials and limitations of the modality in the clinical setting.

The Combination of Radiotherapy With Immunotherapy and Potential Predictive Biomarkers for Treatment of Non-Small Cell Lung Cancer Patients

Radiotherapy is an effective local treatment modality of NSCLC. Its capabilities of eliminating tumor cells by inducing double strand DNA (dsDNA) damage and modulating anti-tumor immune response in irradiated and nonirradiated sites have been elucidated. The novel ICIs therapy has brought hope to patients resistant to traditional treatment methods, including radiotherapy. The integration of radiotherapy with immunotherapy has shown improved efficacy to control tumor progression and prolong survival in NSCLC. In this context, biomarkers that help choose the most effective treatment modality for individuals and avoid unnecessary toxicities caused by ineffective treatment are urgently needed. This article summarized the effects of radiation in the tumor immune microenvironment and the mechanisms involved. Outcomes of multiple clinical trials investigating immuno-radiotherapy were also discussed here. Furthermore, we outlined the emerging biomarkers for the efficacy of PD-1/PD-L1 blockades and radiation therapy and discussed their predictive value in NSCLC.

Immune Checkpoint Inhibitors in Advanced NSCLC: [18F]FDG PET/CT as a Troubleshooter in Treatment Response

Introduction: The aim of this study was to investigate whether [¹⁸F]FDG PET/CT-derived semi-quantitative parameters can predict immunotherapy treatment response in non-small cell lung cancer (NSCLC) patients. Secondly, immune-related adverse events (irAEs) and lymphoid cell-rich organs activation were evaluated. Materials and Methods: Twenty-eight patients who underwent [¹⁸F]FDG PET/CT scans before and at first restaging therapy with immuno-checkpoint inhibitors (ICIs) were retrospectively analyzed. PET-based semi-quantitative parameters extracted from both scans were respectively: SUV_max and SUV_peak of the target lesion, whole-body metabolic tumor volume (MTV_WB), and whole-body total lesion glycolysis (TLG_WB), as well as their interval changes (ΔSUV_maxTL, ΔSUV_peakTL, ΔMTV_WB, ΔTLG_WB). These PET-derived parameters were correlated to controlled disease (CD) assessed by RECIST 1.1. IrAEs, if present, were also described and correlated with clinical benefit (CB). SUV_max of the spleen and bone marrow at restaging scans were also correlated to CB. Results: The CD was achieved in 54% of patients. Out of 28 eligible patients, 13 (46%) experienced progressive disease (PD), 7 showed SD, 7 had PR, and only in one patient CR was achieved. ΔSUV_maxTL (p = 0.002) and ΔSUV_peakTL (p < 0.001) as well as ΔMTV_WB (p < 0.001) and ΔTLG_WB (p < 0.005) were significantly associated with PD vs. non-PD. IrAEs and lymphoid cell-rich organs activation did not correlate with CB. Conclusions: [¹⁸F]FDG PET/CT by using interval changes of PET-derived semi-quantitative parameters could represent a reliable tool in immunotherapy treatment response evaluation in NSCLC patients.

Combining PD-L1 Expression and Standardized Uptake Values in FDG-PET/CT Can Predict Prognosis in Patients With Resectable Non-Small-Cell Lung Cancer

Background

This study aimed to determine the relationship of programmed death-ligand 1 (PD-L1) expression and standardized uptake values in fluorodeoxyglucose–positron emission tomography/computed tomography (FDG-PET/CT) with prognosis in non–small-cell lung cancer (NSCLC).

Methods

We retrospectively analyzed 328 NSCLC patients who underwent lobectomy/segmentectomy with lymph node dissection. PD-L1 expression was detected by immunohistochemically stained using the murine monoclonal antibody clone 22C3. The preoperative maximum standardized uptake value (SUV_max) of FDG-PET/CT at the primary lesion; pathological factors including histological type, microscopic lymphatic, venous, and pleural invasion; and lymph node metastases in resected specimens was determined. Significant prognostic clinicopathologic factors were analyzed by univariate and multivariate analyses.

Results

PD-L1 expression was higher in men, smokers, squamous cell carcinoma, advanced pathologic stages, positive venous invasion, positive pleural invasion, and high preoperative SUV_max (≥3). Postoperative survival analysis showed that both PD-L1 expression and preoperative SUV_max were significantly negative prognostic factors in univariate analysis for overall survival (OS) (P = 0.0123 and P < 0.0001) and relapse-free survival (RFS) (P = 0.0012 and P < 0.0001). Kaplan–Meier survival curves showed that the OS and RFS were the best in patients with negative PD-L1 expression and SUV_max < 3, intermediate in patients with positive PD-L1 expression and SUV_max < 3 and those with negative PD-L1 expression and SUV_max ≥ 3, and poor in patients with positive PD-L1 expression and SUV_max ≥ 3.

Conclusion

Combining PD-L1 expression and preoperative FDG-PET/CT SUV_max in primary tumor might help in accurate prediction of postoperative prognosis in NSCLC patients.

Tumor immunity is related to 18 F-FDG uptake in thymic epithelial tumor

Background

2‐deoxy‐2‐[fluorine‐18] fluoro‐d‐glucose (¹⁸F‐FDG) positron emission tomography (¹⁸F‐FDG‐PET) is a convenient modality to assess the metabolic activity within tumor cells. However, there is no consensus regarding the relationship between ¹⁸F‐FDG uptake and the immune environment in thymic epithelial tumors (TETs). We conducted a clinicopathological study to elucidate the relationship between ¹⁸F‐FDG uptake and programmed death ligands 1 and 2 (PD‐L1/PD‐L2) expression in patients with TETs. Methods: A total of 108 patients with histologically confirmed TETs classified as thymomas or thymic carcinomas who underwent surgical resection or biopsy or needle biopsy and ¹⁸F‐FDG PET before any treatment between August 2007 and March 2020 were enrolled in this study. Tumor specimens underwent immunohistochemical staining for PD‐L1, PD‐L2, GLUT1, HIF‐1α, VEGFR2, VEGF‐C, and β2 adrenergic receptor. Results: High uptakes of SUV_max, SUV_mean, MTV, and TLG were identified in 28 (25.9%), 61 (56.5%), 55 (50.9%), and 55 (50.9%) of 108 patients, respectively. High uptake of SUV_max significantly correlated with PS (performance status) of 1–2, thymic carcinoma, and advanced stage, and SUV_max on ¹⁸F‐FDG uptake displayed a close association with PD‐L1 and PD‐L2 expressions, but not with MTV and TLG. Our analysis revealed that SUV_max was identified as being significant relationship for positive PD‐L1/PD‐L2 expression. GLUT1, HIF‐1α, and VEGFR2 were significantly associated with the expression of PD‐L1/PD‐L2 from the biological viewpoint.

Conclusion

¹⁸F‐FDG accumulation was closely associated with the expression of PD‐L1/PD‐L2, which, in turn, was correlated with glucose metabolism and hypoxia. PD‐L1/PD‐L2 could affect the glucose metabolism and hypoxia in thymic tumor cells.

Diagnostic test accuracy of 18F-FDG PET/CT for prediction of programmed death ligand 1 (PD-L1) expression in solid tumours: a meta-analysis

AIM

To investigate the predictive value of integrated 2-[¹⁸F]-fluoro-2-deoxy-d-glucose (¹⁸F-FDG) positron-emission tomography/computed tomography (PET/CT) for the prediction of programmed death ligand 1 (PD-L1) expression in solid tumours via a systematic review and meta-analysis.

MATERIALS AND METHODS

The PubMed, Cochrane, and EMBASE databases, from the earliest available date of indexing through 31 October 2020, were searched for studies evaluating the diagnostic performance of ¹⁸F-FDG PET/CT for prediction of PD-L1 expression in solid tumours other than lung cancer.

RESULTS

Across seven studies (473 patients), the pooled sensitivity for ¹⁸F-FDG PET/CT was 0.75 (95% confidence interval [CI]: 0.65-0.82) without heterogeneity (I² = 47.2, p=0.08) and a pooled specificity of 0.73 (95% CI: 0.64-0.81) with heterogeneity (I² = 53.8, p=0.04). Likelihood ratio (LR) syntheses gave an overall positive likelihood ratio (LR+) of 2.8 (95% CI: 2.1-3.7) and negative likelihood ratio (LR-) of 0.35 (95% CI: 0.26-0.47). The pooled diagnostic odds ratio (DOR) was 8 (95% CI: 5-13). Hierarchical summary receiver operating characteristic (ROC) curve and indicates that the area under the curve was 0.80 (95% CI: 0.77-0.84).

CONCLUSION

The current meta-analysis showed a moderate sensitivity and specificity of ¹⁸F-FDG PET/CT for the prediction of PD-L1 expression in solid tumours. At present, the literature regarding the use of ¹⁸F-FDG PET/CT for the prediction of PD-L1 expression in solid tumours still limited; thus, further large multicentre studies would be necessary to substantiate the diagnostic accuracy of ¹⁸F-FDG PET/CT for prediction of PD-L1 expression in solid tumours.

Impact of Metabolic Activity in Hepatocellular Carcinoma: Association With Immune Status and Vascular Formation

We evaluated the prognostic value of fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in hepatocellular carcinoma (HCC). Their association with programmed death ligand 1 (PD-L1) expression and vascular formation was further investigated. In this retrospective study, using a database of 418 patients who had undergone ¹⁸F-FDG PET/CT before hepatic resection for HCC, immunohistochemical staining of PD-L1, clusters of differentiation (CD) 8, CD68, and CD34 was performed. Patients with a high maximum standardized uptake value (SUVmax) on ¹⁸F-FDG PET/CT showed a significantly worse recurrence-free survival (RFS) (hazard ratio [HR]: 1.500; 95% confidence interval [CI]: 1.088-2.069; P = 0.0133) and overall survival (OS) (HR: 2.259; 95% CI: 1.276-4.000; P = 0.0052) than patients with a low SUVmax. Logistic regression analysis showed that a high SUVmax in HCC was significantly associated with PD-L1-positive expression (odds ratio: 4.407; 95% CI: 2.265-8.575; P < 0.0001). SUVmax values of HCC were associated with intratumoral CD8-positive T-cell counts (P = 0.0044) and CD68-positive macrophage counts (P = 0.0061). Stratification based on SUVmax, PD-L1 expression, and the vessels that encapsulate tumor clusters (VETC) status was also significantly associated with RFS and OS. SUVmax, VETC, and PDL1 expression were independently predictive of survival on multivariable analysis. Conclusion: Our large cohort study showed that a high SUVmax on ¹⁸F-FDG PET/CT is associated with a poor clinical outcome and PD-L1 expression in patients with HCC. Additionally, stratification of patients based on the combination of SUVmax, PD-L1 expression, and the VETC status predicts poor clinical outcome.

Response Prediction and Evaluation Using PET in Patients with Solid Tumors Treated with Immunotherapy

Simple Summary

In cancer treatment, immunotherapy is increasingly becoming important as a component of first-line treatment and has improved the prognosis of patients since its introduction. A large group of patients, however, do not respond to immunotherapy, and predicting a treatment response remains challenging. Furthermore, evaluating a response using conventional computed tomography (CT) scans is not straightforward due to the different mechanism of action of immunotherapy compared to chemotherapy. This review provides an overview of positron emission tomography (PET) in predicting and evaluating treatment response to immunotherapy.

Abstract

In multiple malignancies, checkpoint inhibitor therapy has an established role in the first-line treatment setting. However, only a subset of patients benefit from checkpoint inhibition, and as a result, the field of biomarker research is active. Molecular imaging with the use of positron emission tomography (PET) is one of the biomarkers that is being studied. PET tracers such as conventional ¹⁸F-FDG but also PD-(L)1 directed tracers are being evaluated for their predictive power. Furthermore, the use of artificial intelligence is under evaluation for the purpose of response prediction. Response evaluation during checkpoint inhibitor therapy can be challenging due to the different response patterns that can be observed compared to traditional chemotherapy. The additional information provided by PET can potentially be of value to evaluate a response early after the start of treatment and provide the clinician with important information about the efficacy of immunotherapy. Furthermore, the use of PET to stratify between patients with a complete response and those with a residual disease can potentially guide clinicians to identify patients for which immunotherapy can be discontinued and patients for whom the treatment needs to be escalated. This review provides an overview of the use of positron emission tomography (PET) to predict and evaluate treatment response to immunotherapy.

Immuno-PET imaging of 68Ga-labeled nanobody Nb109 for dynamic monitoring the PD-L1 expression in cancers

The checkpoint blockade immunotherapy has become a potent treatment strategy for cancers, and programmed death ligand-1 (PD-L1) is a prominent checkpoint ligand that is highly expressed in some cancers. The identification of immune checkpoint marker PD-L1 is critical for improving the success of immunotherapy. Accordingly, the binding specificity and dynamic monitoring property of a non-blocking nanobody tracer ⁶⁸Ga-NOTA-Nb109 to PD-L1 were assessed in this study. The endogenous expression level of PD-L1 in several cancer cells was measured by flow cytometry, Western blot, and cellular uptake assay. Sensitivity and specificity of ⁶⁸Ga-NOTA-Nb109 in monitoring the expression of PD-L1 in vivo were evaluated by PET imaging of different tumor-bearing models (U87, high PD-L1 expression; HCT 116, medium PD-L1 expression; and NCI-H1299, low PD-L1 expression). In vivo PET imaging results agreed well with those detected in vitro. In addition, PET imaging of PD-L1 expression in U87 and NCI-H1299 xenografts using ¹⁸F-FDG was also performed for comparison. The maximum tumor-to-muscle uptake ratio of ⁶⁸Ga-NOTA-Nb109 was more than twofold that of ¹⁸F-FDG in U87 xenograft. The change of PD-L1 expression in NCI-H1299 cells and xenografts induced by cisplatin (CDDP) was sensitively monitored by ⁶⁸Ga-NOTA-Nb109. This study demonstrated the feasibility of tracer ⁶⁸Ga-NOTA-Nb109 for specifically targeting endogenous PD-L1 and dynamic monitoring the change of PD-L1 expression, and could guide the immunotherapy and immunochemotherapy for refractory cancers.

KPNB1-mediated nuclear translocation of PD-L1 promotes non-small cell lung cancer cell proliferation via the Gas6/MerTK signaling pathway

In addition to the role of programmed cell death ligand 1 (PD-L1) in facilitating tumour cells escape from immune surveillance, it is considered as a crucial effector in transducing intrinsic signals to promote tumour development. Our previous study has pointed out that PD-L1 promotes non-small cell lung cancer (NSCLC) cell proliferation, but the mechanism remains elusive. Here we first demonstrated that PD-L1 expression levels were positively correlated with p-MerTK levels in patient samples and NSCLC cell lines. In addition, PD-L1 knockdown led to the reduced phosphorylation level of MerTK in vitro. We next showed that PD-L1 regulated NSCLC cell proliferation via Gas6/MerTK signaling pathway in vitro and in vivo. To investigate the underlying mechanism, we unexpectedly found that PD-L1 translocated into the nucleus of cancer cells which was facilitated through the binding of Karyopherin β1 (KPNB1). Nuclear PD-L1 (nPD-L1), coupled with transcription factor Sp1, regulated the synthesis of Gas6 mRNA and promoted Gas6 secretion to activate MerTK signaling pathway. Taken together, our results shed light on the novel role of nPD-L1 in NSCLC cell proliferation and reveal a new molecular mechanism underlying nPD-L1-mediated Gas6/MerTK signaling activation. All above findings provide the possible combinational implications for PD-L1 targeted immunotherapy in the clinic.

The Value of 18F-FDG PET/CT in Predicting the Response to PD-1 Blocking Immunotherapy in Advanced NSCLC Patients with High-Level PD-L1 Expression

BACKGROUND

The objective of this study was to evaluate if ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT)-derived parameters are useful in predicting response and survival after programmed cell death protein 1 (PD-1) blocking immunotherapy in patients with advanced NSCLC characterized by a high programmed death-ligand 1 (PD-L1) expression (≥50%) on immunohistochemistry.

PATIENTS AND METHODS

In 30 patients with advanced stage IV non-small-cell lung cancer (NSCLC) and high PD-L1 expression, ¹⁸F-FDG PET/CT parameters before start of treatment with PD-1 blocking immunotherapy were evaluated retrospectively. In 24 out of the 30 patients, ¹⁸F-FDG PET/CT was available 8 to 9 weeks after start of the treatment. Response Evaluation Criteria in Solid Tumors (RECIST 1.1) and metabolic responses assessed on ¹⁸F-FDG PET/CT were compared.

RESULTS

Median follow-up was 20 months (range, 4.2-37.6). Median PD-L1 expression was 80%. The objective response rate with RECIST 1.1 was 53.3%. Median progression-free survival (PFS) was 12.4 months (95% confidence interval [CI], 1.0-37.8), and median overall survival (OS) was 14.9 months (95% CI, 2.4-38.2). Baseline ¹⁸F-FDG PET/CT parameters did not differ between responders and non-responders (all P > .05). The maximum standardized uptake value (SUVmax) was the only ¹⁸F-FDG PET/CT parameter associated with PFS (P = .04), with a trend for OS (P = .06). At first evaluation, response according to total metabolic tumor volume (TMTV) and total lesion glycolysis (TLG) were associated with PFS and OS (both P < .0001). This was not the case for RECIST 1.1 (P = .29 for PFS and P = .38 for OS).

CONCLUSION

Clinical response and survival were independent from metabolic tumor volume at baseline. Reduction of metabolic tumor volume after 8 to 9 weeks of treatment was a better predictor for prolonged survival than RECIST 1.1.

Correlation Between Dual-Time-Point FDG PET and Tumor Microenvironment Immune Types in Non-Small Cell Lung Cancer

Purpose

Dual-time-point ¹⁸F-fluorodeoxyglucose positron emission tomography (DTP ¹⁸F-FDG PET), which reflects the dynamics of tumor glucose metabolism, may also provide a novel approach to the characterization of both cancer cells and immune cells within the tumor immune microenvironment (TIME). We investigated the correlations between the metabolic parameters (MPs) of DTP ¹⁸F-FDG PET images and the tumor microenvironment immune types (TMITs) in patients with non-small cell lung cancer (NSCLC).

Methods

A retrospective analysis was performed in 91 patients with NSCLC who underwent preoperative DTP ¹⁸F-FDG PET/CT scans. MPs in the early scan (eSUVmax, eSUVmean, eMTV, eTLG) and delayed scan (dSUVmax, dSUVmean, dMTV, dTLG) were calculated, respectively. The change in MPs (ΔSUVmax, ΔSUVmean, ΔMTV, ΔTLG) between the two time points were calculated. Tumor specimens were analyzed by immunohistochemistry for PD-1/PD-L1 expression and CD8⁺ tumor-infiltrating lymphocytes (TILs). TIME was classified into four immune types (TMIT I ~ IV) according to the expression of PD-L1 and CD8⁺ TILs. Correlations between MPs with TMITs and the immune-related biomarkers were analyzed. A composite metabolic signature (Meta-Sig) and a combined model of Meta-Sig and clinical factors were constructed to predict patients with TMIT I tumors.

Results

eSUVmax, eSUVmean, dSUVmax, dSUVmean, ΔSUVmax, ΔSUVmean, and ΔTLG were significantly higher in PD-L1 positive patients (p = 0.0007, 0.0006, < 0.0001, < 0.0001, 0.0002, 0.0002, 0.0247, respectively), and in TMIT-I tumors (p = 0.0001, < 0.0001, < 0.0001, < 0.0001, 0.0009, 0.0009, 0.0144, respectively). Compared to stand-alone MP, the Meta-Sig and combined model displayed better performance for assessing TMIT-I tumors (Meta-sig: AUC = 0.818, sensitivity = 86.36%, specificity = 73.91%; Model: AUC = 0.869, sensitivity = 77.27%, specificity = 82.61%).

Conclusion

High glucose metabolism on DTP ¹⁸F-FDG PET correlated with the TMIT-I tumors, and the Meta-Sig and combined model based on clinical and metabolic information could improve the performance of identifying the patients who may respond to immunotherapy.

Association between 18F-FDG metabolic activity and programmed death ligand-1 (PD-L1) expression using 22C3 immunohistochemistry assays in non-small cell lung cancer (NSCLC) resection specimens

OBJECTIVE

This study sought to investigate the association between ¹⁸F-fludeoxyglucose (¹⁸F-FDG) uptake in positron emission tomography/CT (PET/CT) scans and different programmed death ligand-1 (PD-L1) expression conditions in non-small cell lung cancer (NSCLC).

METHODS

From October 2017 to December 2019, NSCLC was retrospectively identified in 419 consecutive patients who underwent ¹⁸F-FDG PET/CT scans and PD-L1 expression tests using the PD-L1 22C3 assay. The association between clinicopathological characteristics and PD-L1 expression was assessed.

RESULTS

The frequency of PD-L1-positive tumours was 38.2% (160/419) in NSCLC. In NSCLC, the multivariate analysis showed a high maximum standardised uptake value (SUVmax) (p < 0.0001) and an EGFR wild type genotype (p = 0.027) was significantly associated with PD-L1-positivity. In adenocarcinoma (ADC), the multivariate analysis showed that a high SUVmax (p < 0.0001) was significantly associated with PD-L1-positivity. In NSCLC and ADC, a Mann-Whitney U test showed significant differences between groups with PD-L1 high expression and PD-L1 low expression levels in terms of SUVmax (p = 0.011 and p = 0.013, respectively). The results of the receiver operating characteristic curve analysis showed that the area under the curve of the SUVmax was 0.767 (95% CI, 0.720-0.814; p < 0.0001) and 0.712 (95% CI, 0.651-0.774; p < 0.0001) in NSCLC and ADC, respectively.

CONCLUSION

The study demonstrates that the SUVmax was significantly associated with PD-L1 expression in NSCLC and ADC. The SUVmax was significantly different between the PD-L1 high and low expression conditions, as quantified using a PD-L1 22C3 assay.

ADVANCES IN KNOWLEDGE

This study provides direct evidence that SUVmax as a metabolic biomarker may help select patients with NSCLC likely to benefit from pembrolizumab.

Value of 18F-FDG-PET to predict PD-L1 expression and outcomes of PD-1 inhibition therapy in human cancers

Anti-programmed cell death-1 (PD-1)/programmed death ligand-1 (PD-L1) antibodies are administered in varied human cancer types. The expression of PD-L1 within tumor cells has been identified as a predictive marker, although assessing its expression has benefitted only patients with non-small cell lung cancer (NSCLC) or head and neck cancer. Whereas, more than 75% of the patients with NSCLC showing partial response to PD-1 blockade therapy experienced long-term survival for more than 5-years Thus, identifying the responders to PD-1 blockade at early phase after its initiation is of clinical importance. The 2-deoxy-2-[fluorine-18] fluoro-D-glucose (¹⁸F-FDG) on positron emission tomography (PET) can evaluate any tumor shrinkage by assessing the metabolic tumor volume at an earlier phase than conventional modalities such as computed tomography (CT). While several reports describe the correlation of PD-L1 expression with ¹⁸F-FDG uptake rate in the tumor cells, it remains to be delineated whether this rate determined by the glucose metabolism and hypoxia is associated with the status of immune microenvironment, including the expression of PD-L1. Moreover, details of the relationship between expression of PD-L1 and ¹⁸F-FDG uptake is still unclear. Therefore, we reviewed the clinical significance of ¹⁸F-FDG uptake on PET as a predictor of the efficacy of PD-1 blockade therapy, by correlating with the expression of PD-L1, in patients with several neoplasms.

Radiological assessment of response and adverse events associated with novel systemic oncological therapies

The last decade has seen a paradigm shift in medical oncology treatment with the rise of novel systemic agents, principally molecular targeted therapy and immunotherapy. These new groups of anti-cancer treatment have revolutionised the prognostic landscape for certain patient cohorts with advanced disease, and it is hoped that through ongoing extensive clinical research, significant survival benefits may be demonstrated in the majority of tumour types. However, radiological response assessment of these new agents has become more nuanced for radiologists, as the behaviour of both responding and progressing tumour burden can be more diverse than with conventional chemotherapy. Additionally, radiologists need to be aware of adverse events associated with these treatments as some side effects carry a high morbidity/mortality and may manifest radiologically before they become clinically apparent. This review discusses radiological response assessment and adverse events associated with these novel agents, which have become fundamental aspects of systemic oncological therapy.

Response evaluation after immunotherapy in NSCLC: Early response assessment using FDG PET/CT

The present study aimed to evaluate the role of early F-18 2-deoxy-2-[fluorine-18] fluoro-D-glucose positron emission tomography/computed tomography (FDG PET/CT) in non-small cell lung cancer patients undergoing immune checkpoint inhibitor (ICI) treatment.Twenty-four non-small cell lung cancer patients who received nivolumab or pembrolizumab and underwent FDG PET/CT as an interim analysis after 2 or 3 cycles of ICI treatment were retrospectively enrolled. Tumor response was assessed using the PET Response Criteria in Solid Tumors 1.0 (PERCIST) and the European Organization for Research and Treatment of Cancer (EORTC) criteria after 2 or 3 cycles of ICI treatment (SCAN-1) and after an additional 2 cycles of ICI treatment (SCAN-2). The best overall response was determined by FDG PET/CT or chest CT at ≥ 3 months after therapy initiation, and the clinical benefit was investigated. progression-free survival was investigated, and its correlation with clinicopathologic and metabolic parameters was examined using a Cox multivariate proportional hazards model.In the interim analysis, 4 patients achieved a complete metabolic response (CMR), 1 patient exhibited a partial metabolic response (PMR), and 14 patients had Progressive metabolic disease (PMD) according to the PERCIST and EORTC criteria. Four patients showed stable metabolic disease (SMD) according to the PERCIST criteria, and 2 patients showed different responses (i.e., PMR) according to the EORTC criteria. Patients with a CMR or PMR at SCAN-1 had a clinical benefit. Among the 4 patients with SMD at SCAN-1, only 1 experienced a clinical benefit regardless of the percent change in the peak standardized uptake value. Two patients with discordant response assessments between the PERCIST and EORTC criteria showed conflicting clinical benefits. Among the 14 patients with PMD, none experienced any clinical benefit. Only metabolic parameters were significant factors for predicting progression in the multivariate analysis (peak standardized uptake value and metabolic tumor volume, HRs of 1.18 and 1.00, respectively).Based on early F-18 FDG PET/CT after ICI treatment, metabolic parameters could predict post-treatment progression. Responses after ICI treatment were correctly assessed in patients with a CMR, a PMR, and PMD, but patients with SMD required a meticulous follow-up because of varying clinical benefits.

The potential of 18F-FDG PET/CT in predicting PDL1 expression status in pulmonary lesions of untreated stage IIIB-IV non-small-cell lung cancer

OBJECTIVES

To investigate the potential of 2-deoxy-2(¹⁸F)fluoro-d-glucose (¹⁸F-FDG) combined positron emission tomography and computed tomography (PET/CT) in predicting programmed cell death ligand-1 (PDL1) expression status in pulmonary lesions of advanced non-small-cell lung cancer (NSCLC).

MATERIALS AND METHODS

This retrospective study includes 133 untreated stage IIIB-IV NSCLC patients who underwent pulmonary lesion biopsy for PDL1 immunochemistry 1-4 weeks after ¹⁸F-FDG PET/CT scanning, randomly assigned to cohorts for modelling and validation of PDL1 expression predictors. Mean and maximum standard uptake values (pSUVmean and pSUVmax), metabolic tumour volume (pMTV), and total lesion glycolysis (pTLG) of primary lesions were determined. PDL1 expression in pulmonary lesions (pPDL1) was determined using tumour proportion score (TPS), and pPDL1 TPS < 1%, 1-49 %, and ≥ 50 % were considered as pPDL1-negative, pPDL1-moderate, and pPDL1-strong, respectively.

RESULTS

pSUVmean and pSUVmax values were increased with the increase of pPDL1 levels, whereas pMTV and pTLG values were not associated with pPDL1 levels. In the modelling cohort, we found that pSUVmax rather than pSUVmean was an independent predictor for pPDL1-negative, pPDL1-moderate, and pPDL1-strong, whereas pSUVmax < 14.4, 14.4-17.5, and > 17.5 were suggested as predictors for pPDL1-negative, pPDL1-moderate, and pPDL1-strong, respectively (odds ratio: 4.82, 3.92, and 4.45, respectively; P = 0.002, 0.021, and 0.020, respectively). In the validation cohort, pSUVmax < 14.4, 14.4-17.5, and > 17.5 showed significantly high probabilities of being pPDL1-negative, pPDL1-moderate, and pPDL1-strong, respectively (P = 0.006). The accuracies of pSUVmax < 14.4, 14.4-17.5, and > 17.5 predicting pPDL1-negative, pPDL1-moderate, and pPDL1-strong, respectively, in validation cohort, were 66.7 %, 75.8 %, and 84.8 %, respectively.

CONCLUSION

pSUVmax on ¹⁸F-FDG PET/CT is a potential biomarker for pPDL1 TPS < 1%, 1-49 %, and ≥ 50 % in untreated stage IIIB-IV NSCLC, and therefore may be helpful for determining immunotherapeutic strategy for advanced NSCLC.

Assessing Immunotherapy with Functional and Molecular Imaging and Radiomics

Immunotherapy is changing the treatment paradigm for cancer and has introduced new challenges in medical imaging. Because not all patients benefit from immunotherapy, pretreatment imaging should be performed to identify not only prognostic factors but also factors that allow prediction of response to immunotherapy. Follow-up studies must allow detection of nonresponders, without confusion of pseudoprogression with real progression to prevent premature discontinuation of treatment that can benefit the patient. Conventional imaging techniques and classic tumor response criteria are limited for the evaluation of the unusual patterns of response that arise from the specific mechanisms of action of immunotherapy, so advanced imaging methods must be developed to overcome these shortcomings. The authors present the fundamentals of the tumor immune microenvironment and immunotherapy and how they influence imaging findings. They also discuss advances in functional and molecular imaging techniques for the assessment of immunotherapy in clinical practice, including their use to characterize immune phenotypes, assess patient prognosis and response to therapy, and evaluate immune-related adverse events. Finally, the development of radiomics and radiogenomics in these therapies and the future role of imaging biomarkers for immunotherapy are discussed. Online supplemental material is available for this article. ^©RSNA, 2020.

Predictive value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography for PD-L1 expression in non-small cell lung cancer: A systematic review and meta-analysis

Background

The purpose of the current study was to investigate the predictive value of 18F‐fluorodeoxyglucose positron emission tomography/computed tomography (18F‐FDG PET/CT) for programmed death ligand 1 (PD‐L1) in non‐small cell lung cancer (NSCLC) patients through a systematic review and meta‐analysis.

Methods

The PubMed, Cochrane, and EMBASE database, from the earliest available date of indexing through 30 April 2020, were searched for studies evaluating the diagnostic performance of 18F‐FDG PET/CT for prediction of PD‐L1 expression in NSCLC patients.

Results

Across six studies (1739 patients), the pooled sensitivity for 18F‐FDG PET/CT was 0.72 (95% CI: 0.58–0.82) with heterogeneity (I² = 90.9, P < 0.001) and a pooled specificity of 0.69 (95% CI: 0.64–0.74) with heterogeneity (I² = 77.9, P < 0.001). Likelihood ratio (LR) syntheses gave an overall positive likelihood ratio (LR +) of 2.3 (95% CI: 1.8–2.9) and negative likelihood ratio (LR‐) of 0.41 (95% CI: 0.26–0.63). The pooled diagnostic odds ratio (DOR) was six (95% CI: 3–11). Hierarchical summary receiver operating characteristic (ROC) curve indicated that the area under the curve was 0.74 (95% CI: 0.70–0.78).

Conclusions

The current meta‐analysis showed a moderate sensitivity and specificity of 18F‐FDG PET/CT for the prediction of PD‐L1 expression in NSCLC patients. The DOR was low and the likelihood ratio scatter‐gram indicated that 18F‐FDG PET/CT might not be useful for the prediction of PD‐L1 expression in NSCLC patients and not for its exclusion.

Key points

Significant findings of the study

The current meta‐analysis showed a moderate sensitivity and specificity of 18F‐FDG PET/CT for the prediction of PD‐L1 expression in NSCLC patients. The DOR was low and the likelihood ratio scattergram indicated that 18F‐FDG PET/CT might not be useful for the prediction of PD‐L1 expression in NSCLC patients and not for its exclusion.

What this study adds

This study concluded that the role of 18F‐FDG PET/CT in predicting tumor expression of PD‐L1 should be further elucidated.

Tumor metabolic volume by 18F-FDG-PET as a prognostic predictor of first-line pembrolizumab for NSCLC patients with PD-L1 ≥ 50

There is a lack of markers for predicting favorable outcomes after pembrolizumab therapy in patients with non-small cell lung cancer (NSCLC) with programmed death ligand-1 (PD-L1) expression ≥ 50%. This retrospective study examined the prognostic significance of 2-deoxy-2-[18F] fluoro-d-glucose (¹⁸F-FDG) uptake as a predictive marker of first-line pembrolizumab. Forty-eight patients with previously untreated NSCLC and PD-L1 expression levels ≥ 50% who underwent ¹⁸F-FDG-positron emission tomography (PET) just before administration of pembrolizumab monotherapy were eligible and underwent assessment of metabolic tumor volume (MTV), total lesion glycolysis (TLG), and maximum of standardized uptake value (SUV_max) on ¹⁸F-FDG uptake. The objective response rate, median progression-free survival, and median overall survival were 51.1%, 7.1 months, and 18.6 months, respectively. In univariate survival analyses, high MTV was barely a significant prognostic predictor and was confirmed as an independent factor linked to worse outcomes in multivariate analysis, predominantly in patients with a histological diagnosis of adenocarcinoma. A high MTV was significantly associated with distant metastases (especially bone metastasis), C-reactive protein (CRP) level, and PD-L1 expression ≥ 75%. Metabolic tumor activity assessed as MTV from ¹⁸F-FDG uptake predicted the prognosis after first-line pembrolizumab treatment in patients with NSCLC and PD-L1 expression ≥ 50%, especially for adenocarcinoma.

PD-L1 in Lung Adenocarcinoma: Insights into the Role of 18F-FDG PET/CT

Purpose

This study aimed to evaluate the role of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) in expression of tumor programmed death ligand-1 (PD-L1) expression and prognostic significance of ¹⁸F-FDG PET/CT at different PD-L1 status in patients with lung adenocarcinoma.

Patients and Methods

Seventy-three patients with primary lung adenocarcinoma who received ¹⁸F-FDG PET/CT before treatment were retrospectively included in this study. Expression of tumor PD-L1, programmed death-1 (PD-1) and glucose metabolic parameters were evaluated.

Results

Tumor PD-L1 expression was positively correlated with maximum standardized uptake value (SUVmax), total lesion glycolysis (TLG), hexokinase II (HK-II) and glucose transporter 1 (GLUT-1) (P<0.0001 for all). SUVmax was a unique independent predictor of tumor PD-L1 expression, with an optimal cut-off value of 9.5. For all the patients, tumor stage (P<0.001) and SUVmax (P=0.009) were independent prognostic indicators of disease-free survival (DFS)/progression-free survival (PFS) while carcino-embryonic antigen (CEA) (P=0.003), Ki67 (P=0.042), PD-L1 (P=0.048) and TLG (P=0.004) were independent prognostic indicators of overall survival (OS). Tumor stage (P=0.004) and SUVmax (P=0.022) were independent prognostic indicators of DFS/PFS while TLG (P=0.012) and CEA (P=0.045) were independent prognostic indicators of OS in the PD-L1-positive group. In the PD-L1-negative group, tumor stage (P=0.002) and CEA (P=0.006) were unique independent prognostic indicators of DFS/PFS and OS, respectively.

Conclusion

¹⁸F-FDG PET/CT may potentially predict tumor PD-L1 expression and play a role in predicting prognosis of PD-L1/PD-1 immunotherapy in lung adenocarcinoma.

Relationship between SP142 PD-L1 Expression and 18F-FDG Uptake in Non-Small-Cell Lung Cancer

Objectives

Immune checkpoint blockers constitute the first-line treatment for advanced non-small-cell lung cancer (NSCLC) with ≥50% PD-L1 expression. In NSCLC, PD-L1 positivity is correlated with high ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake. However, these studies only included patients undergoing surgical resection, almost all in their early stages. Moreover, differences in ¹⁸F-FDG uptake between NSCLC with high (≥50%) and low (49%) PD-L1 expression remain unknown. We aimed to investigate the association between metabolic parameter ¹⁸F-FDG uptake and PD-L1 expression status in NSCLC patients.

Methods

From February 2017 to June 2018, 428 consecutive NSCLC patients who underwent ¹⁸F-FDG positron emission tomography/computed tomography (PET/CT) and SP142 PD-L1 expression analysis were retrospectively assessed. The association between clinicopathological characteristics and PD-L1 expression was examined.

Results

The frequency of PD-L1-positive tumors was 38.1% (163/428), 28.5% (91/319), and 64.2% (61/95) for NSCLC, adenocarcinoma (ADC), and squamous cell carcinoma (SCC), respectively. Maximal standard uptake (SUVmax) was significantly higher in PD-L1-positive than in PD-L1-negative NSCLC (p < 0.0001), ADC (p < 0.0001), and SCC (p=0.006). SUVmax was significantly higher in NSCLC (p=0.001) and ADC (p=0.003) with high rather than low PD-L1 expression. The receiver operating characteristic curve yielded area under the curve values of 0.726 (95% CI, 0.679–0.774, p < 0.0001), 0.694 (95% CI, 0.634–0.755, p < 0.0001), and 0.625 (95% CI, 0.513–0.738, p=0.044) for NSCLC, ADC, and SCC, respectively.

Conclusion

¹⁸F-FDG tumor uptake is strongly, positively correlated with PD-L1 expression in NSCLC and significantly differs between high and low PD-L1-expressing individuals.

PD-L1 expression correlation with metabolic parameters of FDG PET/CT and clinicopathological characteristics in non-small cell lung cancer

BACKGROUND

Immunotherapy targeting programmed cell death 1 (PD-1) or its ligand 1 (PD-L1) has shown promising results in non-small cell lung cancer (NSCLC) patients. Exploring PD-L1 expression could help to select NSCLC candidates for immunotherapy. Fluorine-18 fluorodeoxyglucose (FDG) PET/CT could provide phenotypic information on malignant tumors. Thus, this study investigated PD-L1 expression correlation with metabolic parameters of FDG PET/CT and clinicopathological characteristics in NSCLC.

METHODS

FDG PET/CT metabolic parameters including maximum standard uptake (SUVmax), metabolic tumor volume and total lesion glycolysis of primary lesion (MTV-P, TLG-P), and combination of primary lesion and metastases (MTV-C, TLG-C) were compared with PD-L1-positive expression in patients with NSCLC. Moreover, clinicopathological characteristics, including age, gender, smoking history, serum tumor markers, tumor location, size, TNM stage, and genetic mutation were also reviewed.

RESULTS

All 374 patients (215 men; 159 women; age 63 ± 9 years) included 283 adenocarcinomas (ACs) and 91 squamous cell carcinomas (SCCs). PD-L1 expression was positive in 27.8% (104/374) cases. SUVmax, TLG-P, and TLG-C of PD-L1 positivity were significantly higher than PD-L1 negativity. Moreover, PD-L1 expression was obviously correlated with man, smoking, and central NSCLC. If ACs and SCCs were separately analyzed, PD-L1 positivity in ACs and SCCs was 21.6% (61/283) and 47.5% (43/91), respectively, and only SUVmax was obviously associated with PD-L1 expression. Furthermore, multivariate analysis revealed that only SUVmax was an independent predictor of PD-L1 positive expression in overall NSCLC, AC, and SCC. Using a SUVmax cut-off value of 12.5, PD-L1 status of NSCLC was predicted by FDG PET/CT with sensitivity, specificity, and accuracy of 65.4%, 86.7%, and 80.7%, respectively.

CONCLUSIONS

PD-L1 expression of NSCLC was related to SUVmax, TLG, man, smoking, and central location. However, only SUVmax was an independent predictor of PD-L1 positivity, which could help to explore the existence of immune checkpoints.

Potential of FDG-PET as Prognostic Significance after anti-PD-1 Antibody against Patients with Previously Treated Non-Small Cell Lung Cancer

It remains unclear whether the accumulation of 2-deoxy-2-[¹⁸F]fluoro-d-glucose (¹⁸F-FDG) before the initiation of anti-programmed death-1 (PD-1) antibody can predict the outcome after its treatment. The aim of this study is to retrospectively examine the prognostic significance of ¹⁸F-FDG uptake as a predictive marker of anti-PD-1 antibody. Eighty-five patients with previously treated non-small cell lung cancer (NSCLC) who underwent ¹⁸F-FDG-positron emission tomography (PET) just before administration of nivolumab or pembrolizumab monotherapy were eligible in our study, and metabolic tumor volume (MTV), total lesion glycolysis (TLG) and the maximum of standardized under value (SUV_max) on ¹⁸F-FDG uptake were assessed. Objective response rate, median progression-free survival and median overall survival were 36.6%, 161 days and 716 days, respectively. The frequency of any immune-related adverse events was significantly higher in patients with low ¹⁸F-FDG uptake on PET than in those with high uptake. By multivariate analysis, the tumor metabolic activity by TLG and MTV was identified as an independent prognostic factor for predicting outcome after anti-PD-1 antibody therapy, but not SUV_max, predominantly in patients with adenocarcinoma. Metabolic tumor indices as TLG and MTV on ¹⁸F-FDG uptake could predict the prognosis after anti-PD-1 antibodies in patients with previously treated NSCLC.

18F-FDG maximum standard uptake value predicts PD-L1 expression on tumor cells or tumor-infiltrating immune cells in non-small cell lung cancer

OBJECTIVES

Programmed cell death-ligand 1 (PD-L1) is expressed on tumor cells (TC) and tumor-infiltrating immune cells (IC). We conducted a retrospective study to investigate the relationship between PD-L1 expression on TC/IC and ¹⁸F-FDG uptake in patients with surgically resected non-small cell lung cancer (NSCLC).

METHODS

Total 362 NSCLC patients (297 adenocarcinoma and 65 squamous cell carcinoma) who underwent preoperative ¹⁸F-FDG-PET/CT imaging were analyzed retrospectively. Immunohistochemistry analysis was performed for PD-L1 expression on TC and IC in NSCLC specimens with 28-8 antibody. The cut-off value of 5% for defining PD-L1 positivity was determined according to previous trials. The association between PD-L1 expression and clinicopathological variables were analyzed, including age, gender, smoking status, tumor diameter, lymph node metastasis, stage and the maximum standardized uptake value (SUVmax).

RESULTS

PD-L1 positive expression was 50.8% (184/362) in NSCLC patients. Its positive expression on TC and IC were 24.3% (88/362) and 42.5% (154/362), respectively. SUVmax was significantly higher in patients with PD-L1 positive expression on TC or IC than that with negative. Multivariate analysis demonstrated that PD-L1 expression were correlated with SUVmax. The best cut-off value of SUVmax for PD-L1 expression on TC/IC was 8.5 [area under the curve (AUC) = 0.607, 95% CI 0.549-0.665, P = 0.001, sensitivity 50.5% and specificity 71.4%] determined by ROC curve.

CONCLUSION

High SUVmax is linked to PD-L1 expression on TC and IC in our patients with surgically resected non-small cell lung cancer. ¹⁸F-FDG-PET/CT imaging may be used to predict the PD-L1 expression on TC and IC in NSCLC patients.

The importance of FDG-PET/CT parameters for the assessment of the immune status in advanced HNSCC

OBJECTIVE

Cancer cells secrete large amounts of lactic acid via aerobic glycolysis. We have shown that lactic acid plays an important role as a proinflammatory and immunosuppressive mediator and promotes tumor progression. Fluorine-18 fluorodeoxyglucose (FDG) uptake detected by positron emission tomography/computed tomography (PET/CT) is considered as a good indicator of aerobic glycolysis in cancer. In this study, we examined the relationships between systemic inflammatory parameters and FDG-PET/CT parameters in advanced head and neck squamous cell carcinoma (HNSCC). Furthermore, we investigated the relationships between FDG-PET/CT parameters and M2-macrophage polarization in HNSCC by assessing the ratio of CD163, a M2-macrophage marker, to CD68, a pan-macrophage marker.

METHODS

This study included 73 advanced HNSCC patients. We assessed the C-reactive protein (CRP) level, white blood cell (WBC) count, neutrophil count, lymphocyte count, and monocyte count as systemic inflammatory markers. Additionally, we assessed the maximum standardized uptake value (SUV_max), mean SUV (SUV_mean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) as FDG-PET/CT parameters.

RESULTS

The CRP level, WBC count, and neutrophil count were correlated with whole-body FDG-PET/CT parameters. The CD163/CD68 ratio was correlated with SUVmax and SUVmean. Our results suggest that systemic inflammation, which is associated with neutrophils, develops in patients with HNSCC having tumors with a larger volume and increased glucose uptake and that M2-macrophage polarization is promoted in HNSCC with increased glucose uptake, SUVmax, and SUVmean. FDG-PET/CT has the potential to reflect cancer-related chronic inflammation and immunosuppressive conditions in cancer patients.

CONCLUSIONS

FDG-PET/CT parameters appear to be useful in assessing the immune status in HNSCC.