Quantitative FDG-PET: a new biomarker in PMBCL

Quantitative PET-based biomarkers in lymphoma: getting ready for primetime

The use of functional quantitative biomarkers extracted from routine PET-CT scans to characterize clinical responses in patients with lymphoma is gaining increased attention, and these biomarkers can outperform established clinical risk factors. Total metabolic tumour volume enables individualized estimation of survival outcomes in patients with lymphoma and has shown the potential to predict response to therapy suitable for  risk-adapted treatment approaches in clinical trials. The deployment of machine learning tools in molecular imaging research can assist in recognizing complex patterns and, with image classification, in tumour identification and segmentation of data from PET-CT scans. Initial studies using fully automated approaches to calculate metabolic tumour volume and other PET-based biomarkers have demonstrated appropriate correlation with calculations from experts, warranting further testing in large-scale studies. The extraction of computer-based quantitative tumour characterization through radiomics can provide a comprehensive view of phenotypic heterogeneity that better captures the molecular and functional features of the disease. Additionally, radiomics can be integrated with genomic data to provide more accurate prognostic information. Further improvements in PET-based biomarkers are imminent, although their incorporation into clinical decision-making currently has methodological shortcomings that need to be addressed with confirmatory prospective validation in selected patient populations. In this Review, we discuss the current knowledge, challenges and opportunities in the integration of quantitative PET-based biomarkers in clinical trials and the routine management of patients with lymphoma.

Prognostic significance of clinical characteristics and 18Fluorodeoxyglucose-positron emission tomography/computed tomography quantitative parameters in patients with primary mediastinal B-cell lymphoma

Objective

Primary mediastinal B-cell lymphoma (PMBCL) lacks standard treatment regimens. This study aimed to identify the disease’s clinical features and prognostic factors.

Methods

This retrospective study included 56 patients with PMBCL. Patient demographic details and clinicopathological characteristics were summarized, and their effects on progression-free survival (PFS) and overall survival (OS) were analyzed.

Results

The median patient age was 29 years (range, 14–56). Twenty-two patients received DA-EPOCH-R (dose-adjusted etoposide, vincristine, and doxorubicin for 96 hours with bolus doses of cyclophosphamide and oral prednisone, as well as rituximab), and 34 patients received R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone). Clinical/laboratory parameters, overall response rates, and 5-year PFS and OS rates did not differ between the treatment groups. Kaplan–Meier analysis indicated that late-stage disease and a higher International Prognostic Index (IPI) were associated with shorter PFS and OS. Furthermore, patients with B symptoms and first-line treatment non-responders exhibited worse OS. ¹⁸Fluorodeoxyglucose-positron emission tomography/computed tomography quantitative parameters, such as higher metabolic tumor volume (MTV) and total lesion glycolysis (TLG), were corrected with shorter PFS.

Conclusions

This study revealed that stage IV disease, higher IPI, and B symptoms were poor prognostic factors in patients with PMBCL. Significantly, higher MTV and TLG portended worse PFS.

End of treatment FDG-PET in primary mediastinal B-cell lymphoma treated with R-chemotherapy: Prognostic indicator and implications for consolidation radiotherapy

The ideal therapeutic regimen in primary mediastinal B-cell lymphoma (PMBCL) is controversial and may include consolidation radiotherapy (RT). An adequate strategy is essential in a population where long-term effects of RT are significant. We evaluated the prognostic value of end-of-treatment (EOT) FDG-PET in 50 patients receiving rituximab and anthracycline-containing chemotherapy and its implications for consolidative RT. Thirty patients (60%) obtained complete metabolic response (CMR), five received consolidation RT. The remaining patients had partial response (14) and progression (6). Of these, 12 received mediastinal RT, six salvage chemotherapy, and two no further treatment. Five-year progression free survival was 100% and 48% (95% CI 30%-77%) in patients with negative and positive EOT FDG-PET, respectively (P < .001). Five-year overall survival for negative and positive EOT FDG-PET was 100% and 67% (95% CI 48%-93%) respectively (P = .001). Within positive EOT FDG-PET cases, an association was found between Deauville score and survival. The negative predictive value (NPV) of EOT FDG-PET for disease relapse/progression was 100% (95% CI 0.88-1.00); the positive predictive value was 47% (95% CI 0.24-0.71). This study demonstrates the importance of metabolic assessment in PMBCL and is relevant for its high NPV. Our data favor the use of EOT FDG-PET for decisions concerning RT.

Primary mediastinal large B cell lymphoma

Primary mediastinal large B cell lymphoma (PMBCL) is an aggressive large B cell lymphoma originating in the mediastinum, that mainly expresses B cell surface molecules, such as CD19, CD20, CD22, andCD79a. Clinically, they are characterized by rapidly increasing anterior mediastinal masses, which can cause compression of the surrounding tissues. The diagnosis of PMBCL mainly depends on the pathological features, imaging examination and clinical features. Currently, the most commonly used therapeutic regimens are R‐CHOP and R‐EPOCH. Radiotherapy is beneficial in some patients, but it can also lead to long‐term toxicity. The research and development of novel therapies are ongoing, and some studies have achieved encouraging results, including those conducted on chimeric antigen receptor‐modified T (CAR‐T) cell therapy and anti‐PD‐1 drugs. However, randomized controlled trials with larger sample sizes are still needed. Positron emission tomography‐computed tomography (PET‐CT) is mainly used to assess the curative effect after treatment and to guide the subsequent treatment strategy.

Continuous infusion chemotherapy, radiotherapy, and FDG-PET are feasible during extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) may be used in extreme circumstances for patients with a mediastinal mass and respiratory failure. We report on a young man with primary mediastinal B-cell lymphoma invading into the trachea, requiring a 40-day ECMO run who underwent fluorodeoxyglucose positron emission tomography (FDG-PET) imaging and treatment with concurrent mediastinal irradiation and continuous infusion chemotherapy while on this life-saving technology. This case illustrates that oncology patients may be managed by multidisciplinary teams for extended periods in extraordinary circumstances using multimodality therapies. Additionally, to our knowledge this is the first case to demonstrate the feasibility of FDG-PET imaging while on ECMO.

SAKK38/07 study: integration of baseline metabolic heterogeneity and metabolic tumor volume in DLBCL prognostic model

Several functional parameters from baseline (18)F-fluorodeoxyglucose positron emission tomography (PET)/computed tomography have been proposed as promising biomarkers of treatment efficacy in diffuse large B-cell lymphoma (DLBCL). We tested their ability to predict outcome in 2 cohorts of DLBCL patients receiving conventional immunochemotherapy (rituximab, cyclophosphamide, doxorubicin hydrochloride, vincristine sulfate, and prednisone [R-CHOP] regimen), either every 14 (R-CHOP14) or 21 days (R-CHOP21). Baseline PET analysis was performed in 141 patients with DLBCL treated with R-CHOP14 in the prospective SAKK38/07 study (NCT00544219) of the Swiss Group for Clinical Cancer Research (testing set). Reproducibility was examined in a validation set of 113 patients treated with R-CHOP21. In the SAKK38/07 cohort, progression-free survival (PFS) at 5 years was 83% for patients with low metabolic tumor volume (MTV) and 59% for those with high MTV (hazard ratio [HR], 3.4; 95% confidence interval [CI], 1.6-7.0; P = .0005), whereas overall survival (OS) was 91% and 64%, respectively (HR, 4.4; 95% CI, 1.9-10; P = .0001). MTV was the most powerful predictor of outcome also in the validation set. Elevated metabolic heterogeneity (MH) significantly predicted poorer outcomes in the subgroups of patients with elevated MTV. A model integrating MTV and MH identified high-risk patients with shorter PFS (testing set: HR, 5.6; 95% CI, 1.8-17; P < .0001; validation set: HR, 5.6; 95% CI, 1.7-18; P = .0002) and shorter OS (testing set: HR, 9.5; 95% CI, 1.7-52; P < .0001; validation set: HR, 7.6; 95% CI, 2.0-28; P = .0003). This finding was confirmed by an unsupervised regression tree analysis indicating that prognostic models based on MTV and MH may allow early identification of refractory patients who might benefit from treatment intensification. This trial was registered at www.clinicaltrials.gov as #NCT00544219.

Prognostic Value of Baseline Total Metabolic Tumor Volume Measured on FDG PET in Patients With Richter Syndrome

PURPOSE

We evaluated the prognostic value of baseline total metabolic tumor volume (TMTV) measured using pretreatment FDG PET for patients with transformation of chronic lymphocytic leukemia (CLL) into diffuse large B-cell lymphoma (DLBCL).

METHODS

A total of 28 patients with transformation of CLL into DLBCL who had undergone FDG PET before treatment were retrospectively reviewed. Univariate and multivariate analysis of conventional clinicopathologic variables (sex, age, World Health Organization performance status score, International Prognostic Index score, Binet stage, lactate dehydrogenase serum level [LDH], platelet count, presence or not of prior therapies for CLL, the time from CLL to Richter syndrome, Ann Arbor stage, Bulky or not) and metabolic parameters (SUVmax, SUVmean, TMTV, and total lesion glycolysis) at the time of the transformation of CLL into DLBCL were tested for overall survival (OS).

RESULTS

Of the 28 patients, 14 patients (50%) died during the follow-up period. Low platelet count, World Health Organization performance status score >1, high LDH, and high TMTV were found to be significant prognostic factors for OS on univariate analysis. The 5-year estimates of OS were 63% in the low metabolic burden group (TMTV ≤1200 cm) and 0% in the high metabolic burden group (TMTV >1200 cm). Multivariate analysis revealed that only high LDH was a significant predictor after adjustment for other variables of OS.

CONCLUSIONS

TMTV extracted from FDG PET at the time of the transformation of CLL into DLBCL is a predictor of OS.

Prognostic Value of Baseline and Interim Total Metabolic Tumor Volume and Total Lesion Glycolysis Measured on 18F-FDG PET-CT in Patients with Follicular Lymphoma

Purpose

The purpose of this study was to investigate the prognostic significance of total metabolic tumor volume (TMTV) and total lesion glycolysis (TLG) in patients with follicular lymphoma (FL) at baseline and mid-treatment with ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) scans.

Methods

The study analyzed data from 48 patients with FL who were treated in Jiangsu Province Hospital and reviewed their baseline PET-CT scans. TMTV and TLG were computed by using the absolute value of 2.0, 2.5, and 3.0 thresholding method, respectively.

Results

Median age was 53 years, 75.0% of patients had stage III to IV disease, 43.8% had a Follicular Lymphoma International Prognostic Index 1 (FLIPI1) score of 3 to 5 and 20.8% had a FLIPI2 score of 3 to 5. Receiver operating characteristic (ROC) curve analysis showed the optimal cut-off values for TMTV3.0 and TLG3.0 were 476.4 (sensitivity, 85.7%; specificity, 78.0%; area under the curve [AUC], 0.760; p=0.003) and 2,676.9 (sensitivity, 71.4%; specificity, 78.0%; AUC, 0.760; p=0.003). On multivariable analysis, TMTV3.0 and TLG3.0 were independent predictors of both progression-free survival (PFS) (hazard ratio [HR], 5.406; 95% confidence interval [CI], 1.326 to 22.040; p=0.019 and HR, 6.502; 95% CI, 1.079 to 39.182; p=0.042) and overall survival (OS) (HR, 4.111; 95% CI, 1.125 to 15.027; p=0.033 and HR, 5.885; 95% CI, 1.014 to 34.148; p=0.049). ROC curve analysis showed the optimal cut-off values for ΔTMTV3.0 and ΔTLG3.0 were 66.3% (sensitivity, 85.7%; specificity, 63.4%; AUC, 0.774; p < 0.001) and 64.5% (sensitivity, 85.7%; specificity, 65.9%; AUC, 0.777; p < 0.001).

Conclusion

Baseline TMTV and TLG are strong predictors of PFS and OS in FL. Furthermore, interim TMTV (ΔTMTV > 66.3%) and TLG (ΔTLG > 64.5%) reduction are valuable tools for early treatment response assessment in FL patients.

Metabolic heterogeneity on baseline 18FDG-PET/CT scan is a predictor of outcome in primary mediastinal B-cell lymphoma

An important unmet need in the management of primary mediastinal B-cell lymphoma (PMBCL) is to identify the patients for whom first-line therapy will fail to intervene before the lymphoma becomes refractory. High heterogeneity of intratumoral 18F-fluorodeoxyglucose (18FDG) uptake distribution on positron emission tomography/computed tomography (PET/CT) scans has been suggested as a possible marker of chemoresistance in solid tumors. In the present study, we investigated the prognostic value of metabolic heterogeneity (MH) in 103 patients with PMBCL prospectively enrolled in the International Extranodal Lymphoma Study Group (IELSG) 26 study, aimed at clarifying the role of PET in this lymphoma subtype. MH was estimated using the area under curve of cumulative standardized uptake value-volume histogram (AUC-CSH) method. Progression-free survival at 5 years was 94% vs 73% in low- and high-MH groups, respectively (P = .0001). In a Cox model of progression-free survival including dichotomized MH, metabolic tumor volume, total lesion glycolysis (TLG), international prognostic index, and tumor bulk (mediastinal mass > 10 cm), as well as age as a continuous variable, only TLG (P < .001) and MH (P < .001) retained statistical significance. Using these 2 features to construct a simple prognostic model resulted in early and accurate (positive predictive value, 89%; negative predictive value, ≥90%) identification of patients at high risk for progression at a point that would allow the use of risk-adapted treatments. This may provide an important opportunity for the design of future trials aimed at helping the minority of patients who harbor chemorefractory PMBCL. The study is registered at ClinicalTrials.gov as NCT00944567.

Prognostic value of baseline, interim and end-of-treatment 18F-FDG PET/CT parameters in extranodal natural killer/T-cell lymphoma: A meta-analysis

METHODS

We searched the PubMed, EMBASE, Cochrane Library and Medline databases for eligible articles. SUVmax, MTV, and TLG on B-PET/CT, DS on I-PET/CT and DS on E-PET/CT were regarded as efficacy data. Combined hazard ratios (HRs) for progression-free survival (PFS) and overall survival (OS) were estimated using RevMan 5.3 software.

RESULTS

Nine trials with a total of 535 ENKTL patients were included. SUVmax, MTV and TLG on B-PET/CT were significantly associated with PFS with HRs of 2.78 (95%CI 1.54-5.03), 3.61 (95%CI 1.96-6.65) and 5.62 (95%CI 1.94-16.33), respectively, and with OS with HRs of 4.78 (95%CI 2.29-9.96), 3.20 (95%CI 1.55-6.60) and 7.76 (95%CI 1.79-33.58), respectively. For the DS on I-PET/CT, the HRs for PFS and OS were 5.15 (95%CI 2.71-9.80) and 5.80 (95%CI 2.28-14.73), respectively. Similarly, the DS on E-PET/CT was a significant predictor of PFS and OS with HRs of 3.65 (95%CI 2.13-6.26) and 3.32 (95%CI 1.79-6.15), respectively.

CONCLUSION

Our results suggest that SUVmax, MTV, TLG on B-PET/CT, DS on I-PET/CT and DS on E-PET/CT may be significant prognostic indicators for PFS and OS in ENKTL patients. Moreover, TLG tends to be superior to SUVmax and MTV on B-PET/CT for predicting survival of ENKTL patients. Therefore, response monitoring and prognostication assessments based on multiple PET/CT parameters should be considered in the management of ENKTL patients.

Prognostic value of baseline metabolic tumor volume in early-stage Hodgkin lymphoma in the standard arm of the H10 trial

We tested baseline positron emission tomography (PET)/computed tomography (CT) as a measure of total tumor burden to better identify high-risk patients with early-stage Hodgkin lymphoma (HL). Patients with stage I-II HL enrolled in the standard arm (combined modality treatment) of the H10 trial (NCT00433433) with available baseline PET and interim PET (iPET2) after 2 cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine were included. Total metabolic tumor volume (TMTV) was measured on baseline PET. iPET2 findings were reported negative (DS1-3) or positive (DS4-5) with the Deauville scale (DS). The prognostic value of TMTV was evaluated and compared with baseline characteristics, staging classifications, and iPET2. A total of 258 patients were eligible: 101 favorable and 157 unfavorable. The median follow-up was 55 months, with 27 progression-free survival (PFS) and 12 overall survival (OS) events. TMTV was a prognosticator of PFS (P < .0001) and OS (P = .0001), with 86% and 84% specificity, respectively. Five-year PFS and OS were 71% and 83% in the high-TMTV (>147 cm³) group (n = 46), respectively, vs 92% and 98% in the low-TMTV group (≤147 cm³). In multivariable analysis including iPET2, TMTV was the only baseline prognosticator compared with the current staging systems proposed by the European Organization for Research and Treatment of Cancer/Groupe d'Etude des Lymphomes de l'Adulte, German Hodgkin Study Group, or National Comprehensive Cancer Network. TMTV and iPET2 were independently prognostic and, combined, identified 4 risk groups: low (TMTV≤147+DS1-3; 5-year PFS, 95%), low-intermediate (TMTV>147+DS1-3; 5-year PFS, 81.6%), high-intermediate (TMTV≤147+DS4-5; 5-year PFS, 50%), and high (TMTV>147+DS4-5; 5-year PFS, 25%). TMTV improves baseline risk stratification of patients with early-stage HL compared with current staging systems and the predictive value of early PET response as well.

Prognostic models for primary mediastinal (thymic) B-cell lymphoma derived from 18-FDG PET/CT quantitative parameters in the International Extranodal Lymphoma Study Group (IELSG) 26 study

The International Extranodal Lymphoma Study Group-26 study evaluated the prognostic role of 18-fluorodeoxyglucose positron-emission tomography (PET) in primary mediastinal large B-cell lymphoma. We assessed quantitative PET parameters at diagnosis and post-treatment in 100 patients. The end-of-therapy total lesion glycolysis (TLG) was the best individual outcome predictor, but the combination of baseline TLG and end-of-therapy visual analysis with Deauville Score (DS) showed a better positive predictive value. A model in which baseline TLG is combined with interim DS might identify patients with shorter progression-free survival. PET metrics combined with interim DS may allow early risk assessment and warrants further studies.

Baseline Metabolic Tumor Volume Predicts Outcome in High-Tumor-Burden Follicular Lymphoma: A Pooled Analysis of Three Multicenter Studies

PURPOSE

Identifying patients at high risk of progression and early death among those with high-tumor-burden follicular lymphoma (FL) is unsatisfactory with current prognostic models. This study aimed to determine the prognostic impact of the total metabolic tumor volume (TMTV) measured at baseline with [¹⁸F]fluorodeoxyglucose/positron emission tomography-computed tomography ([¹⁸F]FDG/PET-CT) scans and its added value to these models.

PATIENTS AND METHODS

A pooled analysis was performed by using patient data and centrally reviewed baseline PET-CT scans for 185 patients with FL who were receiving immunochemotherapy within three prospective trials. TMTV was computed by using the 41% maximum standardized uptake value thresholding method, and the optimal cutoff for survival prediction was determined.

RESULTS

Median age was 55 years, 92% of patients had stage III to IV disease, 37% had a Follicular Lymphoma International Prognostic Index (FLIPI) score of 3 to 5, and 31% had a FLIPI2 score of 3 to 5. With a median follow-up of 64 months, overall 5-year progression-free survival (PFS) was 55% and overall survival (OS) was 92%. Median TMTV was 297 cm³ (quartile 1 through quartile 3, 135 to 567 cm³). The optimal cutoff identified was 510 cm³, with a markedly inferior survival in the 29% of patients with TMTV > 510 cm³. Five-year PFS was 33% versus 65% (hazard ratio [HR], 2.90; P < .001), and 5-year OS was 85% versus 95% (HR, 3.45; P = .010). On multivariable analysis, TMTV (HR, 2.3; P = .002) and FLIPI2 score (HR, 2.2; P = .002) were independent predictors of PFS. In combination, they identify three risk groups: high TMTV and intermediate-to-high FLIPI2 score with 5-year PFS of 20% (HR, 5.0; P < .001), high TMTV or intermediate-to-high FLIPI2 score with 5-year PFS of 46% (HR, 2.1; P = .007), and low TMTV and low FLIP2 with 5-year PFS of 69%.

CONCLUSION

Baseline TMTV is a strong independent predictor of outcome in FL. In combination with FLIPI2 score, it identifies patients at high risk of early progression. It warrants further validation as a biomarker for development of first-line PET-adapted approaches in FL.

Large-scale microarray profiling reveals four stages of immune escape in non-Hodgkin lymphomas

Non-Hodgkin B-cell lymphoma (B-NHL) are aggressive lymphoid malignancies that develop in patients due to oncogenic activation, chemo-resistance, and immune evasion. Tumor biopsies show that B-NHL frequently uses several immune escape strategies, which has hindered the development of checkpoint blockade immunotherapies in these diseases. To gain a better understanding of B-NHL immune editing, we hypothesized that the transcriptional hallmarks of immune escape associated with these diseases could be identified from the meta-analysis of large series of microarrays from B-NHL biopsies. Thus, 1446 transcriptome microarrays from seven types of B-NHL were downloaded and assembled from 33 public Gene Expression Omnibus (GEO) datasets, and a method for scoring the transcriptional hallmarks in single samples was developed. This approach was validated by matching scores to phenotypic hallmarks of B-NHL such as proliferation, signaling, metabolic activity, and leucocyte infiltration. Through this method, we observed a significant enrichment of 33 immune escape genes in most diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) samples, with fewer in mantle cell lymphoma (MCL) and marginal zone lymphoma (MZL) samples. Comparing these gene expression patterns with overall survival data evidenced four stages of cancer immune editing in B-NHL: non-immunogenic tumors (stage 1), immunogenic tumors without immune escape (stage 2), immunogenic tumors with immune escape (stage 3), and fully immuno-edited tumors (stage 4). This model complements the standard international prognostic indices for B-NHL and proposes that immune escape stages 3 and 4 (76% of the FL and DLBCL samples in this data set) identify patients relevant for checkpoint blockade immunotherapies.

Functional Imaging Using 18-Fluorodeoxyglucose PET in the Management of Primary Mediastinal Large B-Cell Lymphoma: The Contributions of the International Extranodal Lymphoma Study Group

Primary mediastinal large B-cell lymphoma (PMLBCL) is recognized as a distinct disease entity. Treatment outcomes appear better than in other diffuse large B-cell lymphoma (DLBCL) types, partly because of their earlier stage at presentation and the younger age of most patients. If initial treatment fails, however, the results of salvage chemotherapy and myeloablative treatment are poor. The need to avoid relapses after initial therapy has led to controversy over the extent of front-line therapy, particularly whether consolidation radiotherapy to the mediastinum is always required and whether the 18-fluorodeoxyglucose ((18)F-FDG) uptake detected by PET-CT scan can be used to determine its requirements. Functional imaging using PET-CT generally allows distinguishing of residual mediastinal masses containing active lymphoma from those with only sclerotic material remaining. The International Extranodal Lymphoma Study Group (IELSG) conducted the prospective IELSG-26 study, which showed that a five-point visual scale can be used to define metabolic response after immunochemotherapy and that a cut point based on liver uptake discriminates effectively between high or low risk of failure, with 5-year progression-free survival (PFS) of 99% versus 68% and 5-year overall survival (OS) of 100% versus 83%. This study also showed that a baseline quantitative PET parameter, namely the total lesion glycolysis describing the metabolic tumor burden, can be a powerful predictor of PMLBCL outcomes and warrants further validation as a biomarker. The ongoing IELSG-37 randomized study addresses the need for consolidation mediastinal radiotherapy in patients in whom a complete metabolic response (CMR) can be seen on PET scans after standard immunochemotherapy.