Comparison of therapeutic evaluation criteria in FDG-PET/CT in patients with diffuse large-cell B-cell lymphoma: Prognostic impact of tumor/liver ratio

The prognostic utility of 18F-FDG PET parameters in lymphoma patients under CAR-T-cell therapy: a systematic review and meta-analysis

Background

Chimeric antigen receptor (CAR) T-cell therapy has attracted considerable attention since its recent endorsement by the Food and Drug Administration, as it has emerged as a promising immunotherapeutic modality within the landscape of oncology. This study explores the prognostic utility of [18F]Fluorodeoxyglucose positron emission tomography ([18F]FDG PET) in lymphoma patients undergoing CAR T-cell therapy. Through meta-analysis, pooled hazard ratio (HR) values were calculated for specific PET metrics in this context.

Methods

PubMed, Scopus, and Ovid databases were explored to search for relevant topics. Dataset retrieval from inception until March 12, 2024, was carried out. The primary endpoints were impact of specific PET metrics on overall survival (OS) and progression-free survival (PFS) before and after treatment. Data from the studies were extracted for a meta-analysis using Stata 17.0.

Results

Out of 27 studies identified for systematic review, 15 met the criteria for meta-analysis. Baseline OS analysis showed that total metabolic tumor volume (TMTV) had the highest HR of 2.66 (95% CI: 1.52-4.66), followed by Total-body total lesion glycolysis (TTLG) at 2.45 (95% CI: 0.98-6.08), and maximum standardized uptake values (SUVmax) at 1.30 (95% CI: 0.77-2.19). TMTV and TTLG were statistically significant (p < 0.0001), whereas SUVmax was not (p = 0.33). For PFS, TMTV again showed the highest HR at 2.65 (95% CI: 1.63-4.30), with TTLG at 2.35 (95% CI: 1.40-3.93), and SUVmax at 1.48 (95% CI: 1.08-2.04), all statistically significant (p ≤ 0.01). The ΔSUVmax was a significant predictor for PFS with an HR of 2.05 (95% CI: 1.13-3.69, p = 0.015).

Conclusion

[18F]FDG PET parameters are valuable prognostic tools for predicting outcome of lymphoma patients undergoing CAR T-cell therapy.

A retrospective head-to-head comparison of the Lugano classification and PERCIST for FDG-PET/CT response assessment in diffuse large B-cell lymphoma

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) is the most common form of lymphoma. European guidelines recommend FDG-PET/CT for staging and end of treatment (EOT) response assessment, mid-treatment response assessment is optional. We compared the Lugano classification and PET Response Criteria In Solid Tumours (PERCIST) for FDG-PET/CT response assessment in DLBCL head-to-head.

METHODS

We retrospectively included patients with DLBCL who underwent first-line R-CHOP(-like) therapy (2013-2020). Interim and EOT FDG-PET/CT response were reevaluated using the Lugano classification and PERCIST. Response was dichotomized into complete metabolic response (CMR) versus non-CMR (interim and EOT) and responders versus nonresponders (interim only). The cutoff for nonresponse at interim was a Deauville score of 5 (DS5) with the Lugano classification and a partial metabolic response with ≤66% reduction in SULpeak using PERCIST (PERCIST66).

RESULTS

In multivariable Cox regression (N = 170), DS5 at interim, PERCIST66 at interim, non-CMR at EOT with the Lugano classification and non-CMR at EOT with PERCIST were predictive of progression-free survival (PFS). The Lugano classification and PERCIST agreed perfectly at interim and EOT and with 98.4% for the identification of nonresponders at interim. The accuracy for predicting events within 2 years of diagnosis was 84.2% for DS-5 at interim, 87.6% for PERCIST66 at interim, 86% for non-CMR with the Lugano classification at EOT and 83.3% for non-CMR with PERCIST at EOT.

CONCLUSION

The Lugano classification and PERCIST were equally predictive of PFS. Nonresponse at interim and non-CMR at EOT were predictive of poor PFS with comparable accuracy for predicting events within 2 years.

Prognostic value of TLR from FDG PET/CT in patients with margin-negative stage IB and IIA non-small cell lung cancer

OBJECTIVES

To evaluate the prognostic value of TLR from PET/CT in patients with resection margin-negative stage IB and IIA non-small cell lung cancer (NSCLC) and compare high-risk factors necessitating adjuvant treatment (AT).

METHODS

Consecutive FDG PET/CT scans performed for the initial staging of NSCLC stage IB and IIA were retrospectively reviewed. The maximum standardized uptake value (SUVmax) of the primary tumor and mean SUV of the liver were acquired. The tumor-to-liver SUV ratio (TLR) was also calculated. Charts were reviewed for basic patient characteristics and high-risk factors for considering AT (poor differentiation, visceral pleura invasion, vascular invasion, tumors > 4 cm, and wedge resection). Statistical analysis was performed using Cox regression analysis and the Kaplan-Meier method.

RESULTS

Of the 112 patients included, 15 (13.4%) died, with a median overall survival (OS) of 43.8 months. Twenty-two patients (19.6%) exhibited recurrence, with median disease-free survival (DFS) of 36.0 months. In univariable analysis, pathology, poor differentiation, and TLR were associated with shorter DFS and OS. In multivariable analysis, TLR (hazard ratio [HR] = 1.263, p = 0.008) and differentiation (HR = 3.087, p = 0.012) were associated with shorter DFS. Also, TLR (HR = 1.422, p < 0.001) was associated with shorter OS.

CONCLUSION

TLR from FDG PET/CT was an independent prognostic factor for recurrence and survival. PET parameters constitute risk factors for consideration in the decision-making for AT in margin-negative stage IB and IIA NSCLC.

CLINICAL RELEVANCE STATEMENT

In this study, TLR from FDG PET/CT was an independent prognostic factor in stage IB-IIA non-small cell cancer patients. Although additional validation studies are warranted, TLR has the potential to be used to determine the need for adjuvant therapy.

KEY POINTS

• High TLR is an independent poor prognostic factor in stage IB-IIA NSCLC. • Adjuvant treatment should be considered in patients with high TLR following complete tumor resection.

Prognostic parameters on baseline and interim [ 18 F]FDG-PET/computed tomography in diffuse large B-cell lymphoma patients

OBJECTIVE

2-[ 18 F]fluoro-2-deoxy- d -glucose PET/computed tomography ([ 18 F]FDG-PET/CT) is a widely used imaging method in the management of diffuse large B-cell lymphomas (DLBCL). Our aim was to investigate the prognostic performance of different PET biomarkers in a multicenter setting.

METHODS

We investigated baseline volumetric values [metabolic tumor volume (MTV) and total lesion glycolysis (TLG), also normalized for body weight] segmented with three different methods [>SUV4 (glob4); 41% isocontour (41pc), and a gradient-based lesion growing algorithm (grad)] and interim parameters [Deauville score, maximal standardized uptake value (ΔSUVmax), modified qPET, and ratio PET (rPET)] alongside clinical parameters (stage, revised International Prognostic Index), using 24-month progression-free survival as the clinical endpoint. Receiver operating characteristics analyses were performed to define optimal cutoff points for the continuous PET parameters.

RESULTS

A total of 107 diffuse large B-cell lymphoma patients were included (54 women; mean age: 53.7 years). MTV and TLG calculations showed good correlation among glob4, 41pc, and grad methods; however, optimal cutoff points were markedly different.Significantly different PFS was observed between low- and high-risk groups according to baseline MTV, body weight-adjusted (bwa) MTV, TLG, bwaTLG, as well as interim parameters Deauville score, ΔSUVmax, mqPET, and rPET. Univariate Cox regression analyses showed hazard ratios (HRs) lowest for bwaMTVglob4 (HR = 2.3) and highest for rPET (HR = 9.09). In a multivariate Cox-regression model, rPET was shown to be an independent predictor of PFS ( P  = 0.041; HR = 9.15). Combined analysis showed that ΔSUVmax positive patients with high MTV formed a group with distinctly poor PFS (35.3%).

CONCLUSION

Baseline MTV and TLG values and optimal cutoff points achieved with different segmentation methods varied markedly and showed a limited prognostic impact. Interim PET/CT parameters provided more accurate prognostic information with semiquantitative 'Deauville-like' parameters performing best in the present study.

Outcomes of Patients with Positive Interim Positron Emission Tomography (PET) Continuing ABVD in the Clinical Setting

Recent prospective clinical trial data suggest that patients with Hodgkin’s lymphoma who continue treatment with ABVD, despite failing to attain a complete metabolic response on interim PET (PET2+), may fare better than previously published. We describe the outcomes of PET2+ patients who continued ABVD and compare the performance of a quantitative measure based on the lesion-to-liver SUV ratio (LLS qPET2+) to that of the subjective Deauville criteria (dvPET2+). We analyzed all patients with newly diagnosed advanced-stage Hodgkin lymphoma treated with frontline ABVD at the Memorial Sloan Kettering Cancer Center between 2008 and 2017. Eligibility was set to correspond with the RATHL inclusion criteria. Images were reviewed by two nuclear medicine physicians and discordant cases were resolved with a third expert in consensus. qPET2+ was defined as LLS ≥ 1.3. We identified 227 patients of whom 25% (57) were qPET2+, but only 14% (31) were dvPET2+. Forty-eight patients (84%) continued ABVD with a 3-year PFS of 70% for qPET2+ and 64% for dvPET2+. In conclusion, interim PET interpretation in clinical practice may be associated with a higher rate of scans deemed positive. Irrespective of the criteria for PET2 positivity, a subset of patients may continue ABVD without a dismal outcome.

Interim FDG18-PET SUVmax Variation Adds Prognostic Value to Deauville 5-Point Scale in the Identification of Patients with Ultra-High-Risk Diffuse Large B Cell Lymphoma

INTRODUCTION

Interim response evaluation by ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (iPET) in diffuse large B cell lymphoma (DLBCL) could be important to rule out disease progression and has been suggested to be predictive of survival. However, treatment guidance by iPET is not yet recommended for DLBCL in clinical practice. We aimed to compare the predictive value of iPET when utilizing the visual Deauville 5-point scale (DS) and the semiquantitative variation of maximum standardized uptake value (ΔSUV_max).

MATERIALS AND METHODS

We included 85 patients diagnosed with DLBCL and uniformly treated with standard protocols. iPET with DS of 1-3 and/or ΔSUV_max ≥66% was defined as negative. Univariable and multivariable Cox regression analyses were performed to determine the independent factors affecting progression free survival (PFS) or overall survival (OS) and to estimate PFS and OS.

RESULTS

iPET positivity, measured by DS or ΔSUV_max, showed predictive value of disease refractoriness, improved by combining DS and ΔSUV_max. After a median follow-up of 50.1 months, iPET was an independent predictor for both PFS and OS when interpreted by DS, but only for PFS by ΔSUV_max. Combined visual and semiquantitative analysis (D4-5 & ΔSUV_max<66%) was an independent predictor of PFS and OS, and allowed to identify an ultra-high-risk subgroup of patients with very dismal outcome, increasing the discriminating capacity for iPET.

CONCLUSION

Our study suggests that combined DS and ΔSUV_max in iPET assessment predicts refractory disease and distinguishes ultra-high-risk DLBCL patients with a very dismal prognosis, who may benefit from PET-guided therapy adjustment.

Baseline 18F-FDG Metabolic Tumor Volume Predicts Response to Rituximab Induction in Post-transplant Lymphoproliferative Disorders: A Multi-institutional Retrospective Study

Post-transplant lymphoproliferative disorder (PTLD) is a rare complication of immunosuppression. Sequential treatment is commonly proposed, combining induction with rituximab (R-induction) followed by either continuation of treatment or addition of chemotherapy depending on response. Response to R-induction, often assessed by CT scan, is a major predictor of overall survival (OS). The aim of the study was to analyze predictive factors of R-induction response, including total metabolic tumor volume (TMTV), and investigate the role of ¹⁸F-FDG PET/CT in response assessment. This retrospective multicenter study is based on patients with PTLD included in the K-VIROGREF cohort. Only patients treated by R-induction with a baseline ¹⁸F-FDG PET/CT were included. Response to R-induction was assessed by ¹⁸F-FDG PET/CT. The optimal threshold of TMTV for rituximab response was determined using receiver operating characteristic curves. Univariate and multivariate analyses were conducted to identify predictive factors of response. A total of 67 patients were included. Survival characteristics were similar to those previously reported: the complete response rate to R-induction was 30%, the 3-year OS estimate was 66%, and the treatment-related mortality was 4%. The optimal threshold for TMTV to predict R-induction response was 135 cm³. The response rate to R-induction was 38% in the 21 patients with TMTV ≥ 135 cm³ and 72% in the 46 patients with TMTV < 135 cm³. TMTV was a significant predictor of response, both at univariate and multivariate analyses (odd ratios = 3.71, P = 0.022). Baseline TMTV is predictive of response to R-induction. Early assessment of patient response is feasible with ¹⁸F-FDG PET/CT.

Prognostic impact of 18F-FDG PET/CT in pathologic stage II invasive ductal carcinoma of the breast: re-illuminating the value of PET/CT in intermediate-risk breast cancer

BACKGROUND

The aim of this study is to investigate the impact of ¹⁸F-FDG PET/CT on prognosis of stage II invasive ductal carcinoma (IDC) of the breast primarily treated with surgery.

METHODS

The clinical records of 297 consecutive IDC with preoperative PET/CT and pathologically staged II in surgery from 2013 to 2017 were retrospectively reviewed. The maximum standardized uptake value (SUVmax), peak standardized uptake value (SUVpeak), tumor-to-liver ratio (TLR), and metabolic tumor volume (MTV) were measured. Association of clinicopathologic factors (age, T stage, N stage, AJCC pathologic stage of IIA or IIB, pathologic prognostic stage, grade, hormonal receptor status, HER2 status, Ki-67, and adjuvant therapy) and PET parameters with DFS was assessed using the Cox proportional hazards model.

RESULTS

There were 35 recurrences and 10 deaths at a median follow-up of 49 months (range 0.8 ~ 87.3). All PET parameters were significantly associated with DFS in univariate analysis but in multivariate analysis, SUVpeak was the only factor significantly associated with DFS (hazard ratio 2.58, 95% confidence interval 1.29-5.15, P = 0.007). In cohorts with higher values of SUVpeak or TLR, patients who received adjuvant chemotherapy had significantly superior DFS.

CONCLUSION

Metabolic parameters derived from preoperative PET/CT was significantly associated with recurrence in stage II IDC primarily treated with surgery. PET/CT can be a powerful prognostic tool in conjunction with novel staging systems and current biomarkers for patients undergoing contemporary therapy. Our results urge to reconsider the currently underestimated value of PET/CT confined to diagnostic aspect and to newly recognize its prognostic impact in these intermediate-risk breast cancer.

Deauville score versus ratio Deauville score in the interpretation of interim 18F-FDG PET-CT and in prediction of outcome in children with FDG-avid extra-nodal lymphomas

Background

Pediatric lymphoma is a common hematological neoplasm, representing the third most frequent childhood malignancy. 18F-fluoro-2-deoxyglucose–positron emission tomography has been found to be useful in lymphoma staging, prediction of prognosis and risk stratification of lymphoma patients. Although the interpretation of interim PET (after two cycles of chemotherapy) using the qualitative visual method of 5-point Deauville score has been widely accepted, semiquantitative methods of interpretation were evaluated by many studies and showed a better prediction of prognosis. The purpose of this study was to evaluate the prognostic role of the semiquantitative ratio Deauville score (rDS), defined as the ratio between target lesion and liver maximum standardized uptake values in children with FDG-avid extra-nodal lymphomas, undergoing interim FDG-PET/CT, and to compare it with the 5-point Deauville score (5p-DS).

Methods

This prospective study included 89 children with FDG-avid extra-nodal lymphoma. Interim PET was interpreted using both visual (5p-DS) and the semiquantitative method (rDS). The visual method depends on visual comparison of FDG uptake between lesions and liver as a reference organ for activity and considered lesions with activity higher than liver to be positive, while the semiquantitative method depends on making a ratio between the most active lesion and liver SUVmax. Receiver operating characteristic approach was applied to identify the optimal cut-point of rDS with respect to response to therapy and prognosis, and the prognostic significance of rDS was compared with 5p-DS.

Results

The ROC analysis for rDS as a predictor of progression showed an optimal cut-point of 1.25. Both 5p-DS and rDS were strong outcome predictors. Patients with negative 5p-DS and patients with rDS < 1.25 had a similar 3-year PFS (87%). Patients with a positive 5p-DS had a 3-year PFS of 67.4%, while patients with rDS > 1.25 had a 3-year PFS of 60%.

Conclusions

rDS could be suggested as an accurate prognostic factor in children with lymphoma undergoing interim FDG-PET/CT. However, larger studies with more homogenous sample regarding histopathological subtypes and chemotherapy lines are needed to confirm these data.

Metabolic Imaging in B-Cell Lymphomas during CAR-T Cell Therapy

Simple Summary

Chimeric antigen receptor–engineered T cells are an innovative therapy in hematologic malignancies, especially in patients with refractory/relapsed B-cell lymphomas. Few studies have analyzed the role of [¹⁸F]FDG PET/CT in this field; this review aims to illustrate the literature data and the major findings related to [¹⁸F]FDG PET/CT use during CAR-T cell therapy in B-cell lymphomas, focusing on the prognostic value of metabolic parameters, as well as on response assessment. Furthermore, this work shows in detail the specific adverse events during CAR-T cell therapy and the role of [¹⁸F]FDG PET/CT imaging in their occurrence.

Abstract

Chimeric antigen receptor–engineered (CAR) T cells are emerging powerful therapies for patients with refractory/relapsed B-cell lymphomas. [¹⁸F]FDG PET/CT plays a key role during staging and response assessment in patients with lymphoma; however, the evidence about its utility in CAR-T therapies for lymphomas is limited. This review article aims to provide an overview of the role of PET/CT during CAR-T cell therapy in B-cell lymphomas, focusing on the prognostic value of metabolic parameters, as well as on response assessment. Data from the literature report on the use of [¹⁸F]FDG PET/CT at the baseline with two scans performed before treatment started focused on the time of decision (TD) PET/CT and time of transfusion (TT) PET/CT. Metabolic tumor burden is the most studied parameter associated with disease progression and overall survival, making us able to predict the occurrence of adverse effects. Instead, for post-therapy evaluation, 1 month (M1) PET/CT seems the preferable time slot for response assessment and in this setting, the Deauville 5-point scale (DS), volumetric analyses, SUVmax, and its variation between different time points (∆SUVmax) have been evaluated, confirming the usefulness of M1 PET/CT, especially in the case of pseudoprogression. Additionally, an emerging role of PET/CT brain scans is reported for the evaluation of neurotoxicity related to CAR-T therapies. Overall, PET/CT results to be an accurate method in all phases of CAR-T treatment, with particular interest in assessing treatment response. Moreover, PET parameters have been reported to be reliable predictors of outcome and severe toxicity.

The role of 18F-FDG PET/CT in patients with diffuse large B-cell lymphoma after radioimmunotherapy using 131I-rituximab as consolidation therapy

Purpose

To evaluate the prognostic value of pretreatment ¹⁸F-FDG PET/CT after consolidation therapy of ¹³¹I-rituximab in patients with diffuse large B-cell lymphoma (DLBCL) who had acquired complete remission after receiving chemotherapy.

Methods

Patients who were diagnosed with DLBCL via histologic confirmation were retrospectively reviewed. All patients had achieved complete remission after 6 to 8 cycles of R-CHOP (rituximab, cyclophosphamide, vincristine, doxorubicin, and prednisolone) chemotherapy after which they underwent consolidation treatment with ¹³¹I-rituximab. ¹⁸F-FDG PET/CT scans were performed before R-CHOP for initial staging. The largest diameter of tumor, maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were obtained from pretreatment ¹⁸F-FDG PET/CT scans. Receiver-operating characteristic curves analysis was introduced for assessing the optimal criteria. Kaplan-Meier curve survival analysis was performed to evaluate both relapse free survival (RFS) and overall survival (OS).

Results

A total of 15 patients (12 males and 3 females) with a mean age of 56 (range, 30–73) years were enrolled. The median follow-up period of these patients was 73 months (range, 11–108 months). Four (27%) patients relapsed. Of them, three died during follow-up. Median values of the largest tumor size, highest SUVmax, MTV, and TLG were 5.3 cm (range, 2.0–16.4 cm), 20.2 (range, 11.1–67.4), 231.51 (range, 15–38.34), and 1277.95 (range, 238.37–10341.04), respectively. Patients with SUVmax less than or equal to 16.9 showed significantly worse RFS than patients with SUVmax greater than 16.9 (5-year RFS rate: 60% vs. 100%, p = 0.008). Patients with SUVmax less than or equal to 16.9 showed significantly worse OS than patients with SUVmax greater than 16.9 (5-year OS rate: 80% vs. 100% p = 0.042).

Conclusion

Higher SUVmax at pretreatment ¹⁸F-FDG PET/CT was associated with better relapse free survival and overall survival in DLBCL patients after consolidation therapy with ¹³¹I-rituximab. However, because this study has a small number of patients, a phase 3 study with a larger number of patients is needed for clinical application in the future.

Lesion-to-Liver SUVmax Ratio to Improve the Prognostic Value of the End of Treatment PET/CT in Diffuse Large B-Cell Lymphoma

Background: Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma worldwide. After first-line therapy, 30–40% of patients relapse or experiment with refractory disease. 18F-FDG PET/CT represents a validated diagnostic tool in post-treatment evaluation of FDG-avid lymphoma, and the Deauville Score (DS), a five-point visual scale, is usually used to assess response. However, the increased number of false positive findings suggested the need to search for new parameters. The aim of this study is to evaluate the prognostic value of End-of-Treatment-PET, comparing DS to the semi-quantitative Lesion-to-Liver ratio (LLR). Methods: newly diagnosed DLBCL patients who underwent 18F-FDG PET/CT were retrospectively analyzed. End-of-Treatment PET findings were assessed first using DS; secondly, assigned the LLR. Results: a total of 105 patients were finally enrolled. ROC analysis showed an LLR of 1.80 as the optimal cutoff value for predicting a disease progression (sensitivity 58%, specificity 95%). Both DS and LLR showed a statistically significant correlation with PFS and OS. LLR resulted in a better diagnostic performance than DS. Conclusions: LLR showed to be a reliable diagnostic method to assess treatment response in DLBCL. The integration of visual and semi-quantitative criteria could help in decision making, improving specificity and PPV.

The value of FDG PET/CT imaging in outcome prediction and response assessment of lymphoma patients treated with immunotherapy: a meta-analysis and systematic review

PURPOSE

Treatment strategies of lymphoid malignancies have been revolutionized by immunotherapy. Because of the inherent property of Hodgkin lymphoma and some subtypes of non-Hodgkin lymphoma as a highly FDG-avid tumor, functional ¹⁸F-FDG PET/CT imaging is already embedded in their routine care. Nevertheless, the question is whether it is still valuable in the context of these tumors being treated with immunotherapy. Herein, we will review the value of ¹⁸F-FDG PET/CT imaging lymphoid tumors treated with immunotherapy regimens.

METHODS

A comprehensive literature search of the PubMed database was conducted on the value of the ¹⁸F-FDG PET/CT for immunotherapy response monitoring of patients with malignant lymphoma. The articles were considered eligible if they met all of the following inclusion criteria: (a) clinical studies on patients with different types of malignant lymphoma, (b) treatment with anti-CD20 antibodies, immune checkpoint inhibitors or immune cell therapies, (c) and incorporated PET/CT with ¹⁸F-FDG as the PET tracer.

RESULTS

From the initial 1488 papers identified, 91 were ultimately included in our study. In anti-CD20 therapy, the highest pooled hazard ratios (HRs) of baseline, early, and late response monitoring parameters for progression-free survival (PFS) belong to metabolic tumor volume (MTV) (3.19 (95%CI: 2.36-4.30)), maximum standardized uptake value (SUVmax) (3.25 (95%CI: 2.08-5.08)), and Deauville score (DS) (3.73 (95%CI: 2.50-5.56)), respectively. These measurements for overall survival (OS) were MTV (4.39 (95%CI: 2.71-7.08)), DS (3.23 (95%CI: 1.87-5.58)), and DS (3.64 (95%CI: 1.40-9.43)), respectively. Early and late ¹⁸F-FDG PET/CT response assessment in immune checkpoint inhibitors (ICI) and immune cell therapy might be an effective tool for prediction of clinical outcome.

CONCLUSION

For anti-CD20 therapy of lymphoma, the MTV as a baseline ¹⁸F-FDG PET/CT-derived parameter has the highest HRs for PFS and OS. The DS as visual criteria in early and late response assessment has higher HRs for PFS and OS compared to the international harmonization project (IHP) visual criteria in anti-CD20 therapy. Early changes in ¹⁸F-FDG PET parameters may be predictive of response to ICIs and cell therapy in lymphoma patients.

18F-FDG PET Improves Baseline Clinical Predictors of Response in Diffuse Large B-Cell Lymphoma: The HOVON-84 Study

We aimed to determine the added value of baseline metabolic tumor volume (MTV) and interim PET (I-PET) to the age-adjusted international prognostic index (aaIPI) to predict 2-y progression-free survival (PFS) in diffuse large B-cell lymphoma. Secondary objectives were to investigate optimal I-PET response criteria (using Deauville score [DS] or quantitative change in SUV_max [ΔSUV_max] between baseline and I-PET4 [observational I-PET scans after 4 cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone administered in 2-wk intervals with intensified rituximab in the first 4 cycles [R(R)-CHOP14]). Methods: I-PET4 scans in the HOVON-84 (Hemato-Oncologie voor Volwassenen Nederland [Haemato Oncology Foundation for Adults in the Netherlands]) randomized clinical trial (EudraCT 2006-005174-42) were centrally reviewed using DS (cutoff, 4-5). Additionally, ΔSUV_max (prespecified cutoff, 70%) and baseline MTV were measured. Multivariable hazard ratio (HR), positive predictive value (PPV), and negative predictive value (NPV) were obtained for 2-y PFS. Results: In total, 513 I-PET4 scans were reviewed according to DS, and ΔSUV_max and baseline MTV were available for 367 and 296 patients. The NPV of I-PET ranged between 82% and 86% for all PET response criteria. Univariate HR and PPV were better for ΔSUV_max (4.8% and 53%, respectively) than for DS (3.1% and 38%, respectively). aaIPI and ΔSUV_max independently predicted 2-y PFS (HR, 3.2 and 5.0, respectively); adding MTV brought about a slight improvement. Low or low-intermediate aaIPI combined with a ΔSUV_max of more than 70% (37% of patients) yielded an NPV of 93%, and the combination of high-intermediate or high aaIPI and a ΔSUV_max of 70% or less yielded a PPV of 65%. Conclusion: In this study on diffuse large B-cell lymphoma, I-PET after 4 cycles of R(R)-CHOP14 added predictive value to aaIPI for 2-y PFS, and both were independent response biomarkers in a multivariable Cox model. We externally validated that ΔSUV_max outperformed DS in 2-y PFS prediction.

Positron emission tomography-imaging assessment for guiding strategy in patients with relapsed/refractory large B-cell lymphoma receiving CAR T cells

The aim of this study was to evaluate the prognostic impact of the F-fluorodeoxyglucose positron emission tomography response at 1 month (M1) and 3 months (M3) after anti-CD19 chimeric antigen receptor (CAR) T-cell therapy in a multicenter cohort of 160 patients with relapsed/refractory large B-cell lymphomas (R/R LBCL). In total, 119 (75%) patients reached M1 evaluation; 64 (53%, 64/119) had a complete response (CR); 91% were Deauville Score (DS) 1-3. Progressionfree survival (PFS) and overall survival (OS) were significantly worse in patients with DS-5 at M1, than in patients with DS 1-3 (PFS hazard ratio [HR]=6.37, 95% confidence interval [CI]: 3.5-11.5 vs. OS HR=3.79, 95% CI: 1.7-8.5) and DS-4 (PFS HR=11.99, 95% CI: 5.0-28.9 vs. OS HR=12.49, 95% CI: 2.8-55.8). The 1-year PFS rates were 78.9% (95% CI: 58.9-89.9) for DS-4 at M1, similar to 67.3% (95% CI: 51.8-78.8) for patients with DS 1-3 at M1, very different to 8.6% (95% CI: 1.8-22.4) for DS-5, respectively. Only eight of 30 (26%) patients with DS-4 progressed. Response at M3 evaluated in 90 (57%) patients was prognostic for PFS with lower discrimination (HR=3.28, 95% CI: 1.5-7.0; P=0.003) but did not predict OS (HR=0.61, 95% CI: 0.2-2.3; P=0.45). Patients with a high baseline total metabolic tumor volume (TMTV) >80 mL had worse PFS (HR=2.05, 95% CI: 1.2-3.5; P=0.009) and OS (HR=4.52, 95% CI: 2.5-8.1; P<0.001) than patients with low TMTV. Multivariable analyses identified baseline elevated lactate dehydrogenase, DS-5, CAR T cells at M1 for PFS and baseline elevated lactate dehydrogenase, TMTV >80 mL, and DS-5 at M1 for OS. In conclusion, baseline TMTV and response at M1 strongly predicts outcomes of patients with R/R LBCL undergoing CAR T-cell therapy.

Current Role of Functional Imaging in the Management of Lymphoma

PURPOSE OF REVIEW

Functional imaging with 18FDG-PET-CT has transformed the staging and response assessment of patients with Hodgkin (HL) and non-Hodgkin lymphoma (NHL). Herein, we review the current role and future directions for functional imaging in the management of patients with lymphoma.

RECENT FINDINGS

Because of its increased sensitivity, PET-CT is the preferred modality for staging of FDG-avid lymphomas. It appears to have a role for interim assessment in patients with HL with adaptive strategies that reduce toxicity in lower risk patients and increase efficacy in those at high risk. Such a role has yet to be demonstrated in other histologies. FDG-PET-CT is also the gold standard for response assessment posttreatment. Newer uses include assessment of total metabolic tumor volume and radiomics in pretreatment prognosis. Whereas PET-CT is more sensitive than other current modalities for staging and response assessment, the future of PET-CT will be in conjunction with other modalities, notably assessment of minimal residual disease and microenvironmental markers to develop risk adaptive strategies to improve the outcome of patients with lymphoma.

The prognostic value of end-of-treatment FDG-PET/CT in diffuse large B cell lymphoma: comparison of visual Deauville criteria and a lesion-to-liver SUVmax ratio-based evaluation system

PURPOSE

The aim of this study was to determine a better criterion for end-of-treatment PET (EoT-PET) assessment and prognostic evaluation of patients with diffuse large B cell lymphoma (DLBCL).

METHOD

EoT-PET scans were assessed using the visual Deauville 5-point scale (5PS) and LLR, the maximum standard uptake value ratio between the lesion and the liver. The cutoff value of LLR was obtained by receiver operator characteristic curve analysis. Patient outcomes were compared using Kaplan-Meier survival analysis. Prognostic indexes of different criteria were compared. Multivariate Cox regression analysis was performed to evaluate the prognostic factors.

RESULTS

Four hundred forty-nine newly diagnosed DLBCL patients who received rituximab-based immunochemotherapy were included, and the median follow-up duration was 41.4 months. Patients with Deauville score (DS) 4 displayed significantly longer PFS and OS compared with patients with DS 5 (both p < 0.001), and they had significantly shorter PFS (p < 0.01) but similar OS (p = 0.057) compared with patients with DS 1-3. The differences in PFS and OS between groups were all significant whether positive EoT-PET was defined as DS 4-5 or DS 5 (all p < 0.001). The optimal cutoff of LLR was 1.83, and both PFS and OS were significantly different between EoT-PET-positive and EoT-PET-negative patients as defined by the cutoff (both p < 0.001). LLR-based criterion displayed higher specificity, positive predictive value, and accuracy than 5PS-based criterion in the prediction of disease progression and death events. In the multivariate analysis, positive EoT-PET (as defined by LLR) was related to unfavorable PFS and OS (both p < 0.001). Additional treatment was not correlated with outcomes of EoT-PET-negative patients either defined by LLR or 5PS or EoT-PET-positive patients classified by 5PS, but it was the only beneficial factor for OS (p < 0.05) in EoT-PET-positive patients with LLR ≥ 1.83.

CONCLUSION

The optimal cutoff of LLR may be superior to Deauville criteria in identifying low-risk DLBCL patients with negative EoT-PET after the first-line immunochemotherapy and sparing them the cost and toxicity of additional treatment.

Outcomes after first-line immunochemotherapy for primary mediastinal B-cell lymphoma: a LYSA study

Primary mediastinal B-cell lymphoma (PMBL) is a rare type of aggressive lymphoma typically affecting young female patients. The first-line standard of care remains debated. We performed a large multicenter retrospective study in 25 centers in France and Belgium to describe PMBL patient outcomes after first-line treatment in real-life settings. A total of 313 patients were enrolled and received rituximab (R) plus ACVBP (doxorubicin, cyclophosphamide, vindesine, bleomycin, and prednisone) (n = 180) or CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) delivered every 14 days (R-CHOP14, n = 76) or 21 days (R-CHOP21, n = 57) and consolidation strategies in modalities that varied according to time and institution, mainly guided by positron emission tomography. Consolidation autologous stem cell transplantation was performed for 46 (25.6%), 24 (31.6%), and 1 (1.8%) patient in the R-ACVBP, R-CHOP14, and R-CHOP21 groups, respectively (P < .001); only 17 (5.4%) patients received mediastinal radiotherapy. The end-of-treatment complete metabolic response rates were 86.3%, 86.8%, and 76.6% (P = .23) in the R-ACVBP, R-CHOP14, and R-CHOP21 groups. The median follow-up was 44 months, and the R-ACVBP, R-CHOP14, and R-CHOP21 three-year progression-free survival probabilities were 89.4% (95% confidence interval [CI], 84.8-94.2), 89.4% (95% CI, 82.7-96.6), and 74.7% (95% CI, 64-87.1) (P = .018). A baseline total metabolic tumor volume (TMTV) ≥360 cm3 was associated with a lower progression-free survival (hazard ratio, 2.18; 95% CI, 1.05-4.53). Excess febrile neutropenia (24.4% vs 5.3% vs 5.3%; P < .001) and mucositis (22.8% vs 3.9% vs 1.8%; P < .001) were observed with R-ACVBP compared with the R-CHOP regimens. Patients with PMBL treated with dose-dense immunochemotherapy without radiotherapy have excellent outcomes. R-ACVBP acute toxicity was higher than that of R-CHOP14. Our data confirmed the prognostic importance of baseline TMTV.

[18F]FDG PET-CT in patients with DLBCL treated with CAR-T cell therapy: a practical approach of reporting pre- and post-treatment studies

PURPOSE

The introduction of CD19-specific chimeric antigen receptor T-cell therapy (CAR-T) for treatment of relapsed/refractory diffuse large B cell lymphoma (R/R DLBCL) gives hope to patients with otherwise dismal prognosis. Therapy outcomes, however, depend upon selection of patients and accurate early identification of non-responders. Patients treated with CAR-T usually undergo [¹⁸F]FDG PET-CT at time of decision (TD), time of CAR-T transfusion (TT), 1 month (M1), and 3 months (M3) post-therapy. The purpose of the current study was to identify the specific parameters that should be addressed when reporting PET-CT studies in the clinical setting of CAR-T therapy.

METHODS

A total of 138 PET-CT scans (30 TD, 42 TT, 44 M1, 22 M3) of 48 patients treated with CAR-T were included. SUVmax, TMTV, and TLG were calculated in all scans. Response was assessed using the Deauville scale and ΔSUVmax method. Overall survival (OS) was the primary endpoint. Median follow-up was 12.8 (IQR 6.4-16.0) months from CAR-T infusion.

RESULTS

In a univariate analysis, TD-SUVmax > 17.1 and TT-SUVmax > 12.1 were associated with shorter OS (Pv < 0.05). In a multivariate analysis, three factors were significantly associated with shorter OS: TD-SUVmax > 17.1 (HR 10.3; Pv < 0.01), LDH > 450 U/l (HR 7.7; Pv < 0.01), and ECOG score > 1 (HR 5.5; Pv = 0.04). Data from TD and TT PET-CT scans were not predictive of toxicity. On M1-PET-CT, patients with a Deauville score > 3 had significantly shorter OS (median 7.9 months, versus not reached, Pv < 0.01). ΔSUVmax ≤ 66% on M1-PET-CT predicted shorter OS when M1-SUVmax was compared to TD-SUVmax (Pv = 0.02) but not to TT-SUVmax (Pv = 0.38).

CONCLUSION

Pre-treatment SUVmax may guide patient selection for CAR-T therapy. On M1-PET-CT, Deauville score and ΔSUVmax from TD may identify early therapy failure. These parameters are easy to obtain and should be included in the PET-CT report.

Interim PET in Diffuse Large B-Cell Lymphoma

In diffuse large B-cell lymphoma, early assessment of treatment response by 18F-FDG PET may trigger treatment modification. Reliable identification of good and poor responders is important. We compared 3 competing methods of interim PET evaluation. Methods: Images from 449 patients participating in the "PET-Guided Therapy of Aggressive Non-Hodgkin Lymphomas" trial were reanalyzed by applying the visual Deauville score and the SUV-based qPET (q = quantitative) and ΔSUVmax scales to interim PET scans performed after 2 cycles of chemotherapy. qPET relates residual lymphoma 18F-FDG uptake to physiologic liver uptake, converting the ordinal Deauville scale into a continuous scale and permitting a direct comparison with the continuous ΔSUVmax scale, which is based on SUVmax changes between baseline and interim scans. Positive and negative predictive values were calculated for progression-free survival. Results: When established thresholds were used to distinguish between good and poor responders (visual Deauville score 1-3 vs. 4-5; ΔSUVmax > 66% vs. ≤ 66%), the positive predictive value was significantly lower with Deauville than ΔSUVmax (38.4% vs. 56.6%; P = 0.03). qPET and ΔSUVmax were strongly correlated on the log scale (Pearson r = 0.75). When plotted along corresponding percentiles, the positive predictive value curves for qPET and ΔSUVmax were superimposable, with low values up to the 85th percentile and a steep rise thereafter. The recommended threshold of 66% SUVmax reduction for the identification of poor responders was equivalent to qPET = 2.26, corresponding to score 5 on the visual Deauville scale. The negative predictive value curves were also superimposable but remained flat between 80% and 70%. Conclusion: Continuous scales are better suited for interim PET-based outcome prediction than the ordinal Deauville scale. qPET and ΔSUVmax essentially carry the same information. The proportion of poor-risk patients identified is less than 15%.

The Role of Interim PET/CT on Survival in Diffuse Large B Cell Lymphoma

BACKGROUND

Diffuse large B cell lymphoma is the most frequent aggressive non-Hodgkin lymphoma. Predicting response and estimating prognosis earlier makes management of this heterogeneous lymphoma more satisfying. Interim PET response is established in Hodgkin Lymphoma to tailor the therapy but results for non-Hodgkin Lymphoma is unconvincing. In the current study evaluation of interim PET and survival outcomes of 103 DLBCL patients is performed.

PATIENTS AND METHODS

About 103 Patients with DLBCL followed up in a single center between 2009 and 2019 were enrolled the study. All patients received R-CHOP chemoimmunotherapy at first line. Interim PET was performed after at least one or more cycles. All PET scans were performed with ¹⁸F-FDG isotope as PET/CT. PET scoring results were evaluated according to the 5-Point Deauville Scoring system defined in the National Comprehensive Cancer Network clinical guidelines for iPET and eotPET. 5-P DS of scores of 1 to 3 were defined as negative scans, and scores of 4 to 5 were considered to be positive scans.

RESULTS

Forty-six (44.7%) Female and 57 (55.3%) male aged between 25 and 83 (median 57) years newly diagnosed DLBCL patients were enrolled in the study. Median PFS was 21 (interquartile range 8.5-53.7) months and median OS was 33.5 (interquartile range 12.5-62.9) months for the total cohort. Positive predictive value of interim PET according to Deauville scoring system was 65.4% and negative predictive value was 77.9%.

CONCLUSION

Our study showed that according to Deauville 5 point scale (D 5PS) scoring system, interim PET-positive patients have shorter both PFS and OS than iPET-negative patients.

End-of-treatment 18F-FDG PET/CT in diffuse large B cell lymphoma patients: ΔSUV outperforms Deauville score

In DLBCL, the Deauville scoring system (DS) is the standard for PET/CT response assessment. An alternative system, based on the semi-quantitative change in standardized uptake values, namely ΔSUVmax, has been reported to be more objective than the DS. We aimed to compare ΔSUVmax and DS for risk stratification of DLBCL patients on end-of-treatment (EoT) PET. 108 consecutive patients were included. 2-year EFS Kaplan-Meier survival analyses and Cox regression models were performed. 2-year EFS was significantly different between favorable ΔSUVmax (favΔ < -86.5%) and unfavorable ΔSUVmax (unfavΔ ≥ -86.5%) patients: 100.0% ± 0.0 versus 58.3% ± 14.2 (p = 0.001). On Cox multivariable regression, ΔSUVmax status was the only independent predictor of 2-year EFS, outperforming DS. Therefore, ΔSUVmax should be computed for non-responder patients, especially DS4, as the 2-year EFS is not different between responders and non-responders in the case of favΔ. Further studies are needed in order to confirm this hypothesis.

Improved prediction of chemoresistance in patients with diffuse large B-cell lymphoma through a new interim positron emission tomography-computed tomography evaluation model

OBJECTIVES

The positron emission tomography (PET) could predict the prognosis of DLBCL patients, but the exact procedure on interim PET (iPET) to determine chemoresistant patients remains elusive.

METHODS

We retrospectively analyzed 593 newly diagnosed DLBCL patients uniformly treated with R-CHOP regimen. Among them, 352 patients diagnosed from August 2010 to December 2016 were included in the test cohort and 241 patients diagnosed from January 2017 to December 2019 were included in the validation cohort. The iPET was evaluated with Deauville criteria and ΔSUVmax method. The reduction of maximal SUV between baseline and after 4 cycles of chemotherapy were defined as ΔSUVmax. The survival functions were depicted using the Kaplan-Meier method and compared with the log-rank test.

RESULTS

Patients with iPET Deauville 4 had heterogeneous outcome and end of treatment complete response rates (eCRR). Combined Deauville with ΔSUVmax method, we proposed a modified-Deauville model: patients with Deauville 4 and ΔSUVmax > 70%, as well as those with Deauville 1-3, were reclassified into the modified-Deauville negative group, while patients with Deauville 4 and ΔSUVmax ≤ 70%, as well as those with Deauville 5, into the modified-Deauville positive group. In the test cohort, 3-year PFS, OS and eCRR of modified-Deauville negative group were 80.2%, 89.9% and 91.8%, significantly higher than those of positive group (12.5%, 27.3% and 29.2%, p ≤ .001). Similar results were found in the validation cohort, that 3-year PFS, OS and eCRR were 87.8%, 95.4%, 96.3% in modified-Deauville negative group, and 27.4%, 32.5%, 13.5% in positive group. Through modified-Deauville model, patients in iPET positive group had very low eCRR and were resistant to conventional chemotherapy.

CONCLUSIONS

The modified-Deauville model could better distinguish DLBCL patients with poor response to chemotherapy. Accordingly, these patients could be recognized early and provided with alternative therapeutic agents, which might improve the clinical outcome of refractory DLBCL patients.

Reproducibility of Baseline Tumour Metabolic Volume Measurements in Diffuse Large B-Cell LymphomA: Is There a Superior Method?

The metabolic tumour volume (MTV) is an independent prognostic indicator in diffuse large B-cell lymphoma (DLBCL). However, its measurement is not standardised and is subject to wide variations depending on the method used. This study aimed to compare the reproducibility of MTV measurement as well as the thresholds obtained for each method and their prognostic values. The baseline MTV was measured in 239 consecutive patients treated at Henri Becquerel Centre by two blinded evaluators. Eight methods were compared: 3 absolute (SUV (standardised uptake value) ≥ 2.5; SUV≥ liver SUVmax; SUV≥ PERCIST SUV), 1 percentage SUV threshold method (SUV ≥ 41% SUVmax) and 4 adaptive methods (Daisne, Nestle, Fitting, Black). The intraclass correlation coefficients were excellent, from 0.91 to 0.96, for the absolute SUV methods, Black and Nestle methods, and good for 41% SUVmax, Fitting and Daisne methods (0.82 to 0.88), with a significantly lower variability with absolute methods compared to 41% SUVmax (p < 0.04). Thresholds were found to be specific to each segmentation method and ranged from 295 to 552 cm³. There was a strong correlation between the MTV and patient prognosis regardless of the segmentation method used (p = 0.001 for PFS and OS). The largest inter-observer cut-off variability was observed in the 41% SUVmax method, which resulted in more inter-observer disagreements in the classification of patients between high and low MTV groups. MTV measurements based on absolute SUV criteria were found to be significantly more reproducible than those based on 41% SUVmax criteria. The threshold was specific for each of eight segmentation methods, but all predicted prognosis.

The prognostic role of end-of-treatment FDG-PET/CT in diffuse large B cell lymphoma: a pilot study application of neural networks to predict time-to-event

PURPOSE

To evaluate the prognostic role of end-of-treatment (EoT) FDG-PET/CT parameters in diffuse large B cell lymphoma (DLBCL), and then to explore a pilot application of Neural Networks (NN) in predicting time-to-relapse.

METHODS

For conventional survival analysis, parameters as Deauville score (DS) and quantitative extension of DS (qPET) were correlated to adverse events as relapse or progression in the follow-up. To build NN and conventional multi-regression models (MM) for time-to-event prediction, patients with residual FDG uptake (DS ≥ 2) and an adverse event were divided into a training and a test group. Models developed on the training group were evaluated in the test group. Pearson correlation coefficient (R) and mean relative error between observed and forecasted time-to-event were calculated.

RESULTS

FDG-PET/CT data of 308 patients with DLBCL were analyzed. DS and qPET were prognostic factors in conventional univariate analysis. Positive and negative predictive values, respectively, were 55% and 83% for DS 4-5, 89% and 82% for positive qPET. Focusing on 37 relapsed patients with a residual FDG uptake, R between observed and forecasted time-to-event was of 0.63 in the NN model and 0.49 in the MM. Mean relative error in predicting time-to-event was of 58% for NN and 67% for MM.

CONCLUSIONS

EoT FDG-PET/CT visual score (DS) is a strong outcome predictor in DLBCL in a large monocentric cohort. The semi-quantitative parameter qPET may increase this prognostic performance. A pilot NN model applied on residual FDG uptake parameters seems to predict time-to-event in the follow-up.

SUVmax-based assessment of PET response shows a superior specificity to Deauville criteria for predicting recurrence in Hodgkin's lymphoma

One of the limitations of ¹⁸FDG PET/CT for therapeutic evaluation in Hodgkin's Lymphoma is the relatively high rate of false positive uptake. SUV_max reduction (ΔSUV_max) and tumor/liver ratio (TLr) are promising tools for response assessment in lymphoma. We determined the optimal cutoff values for ΔSUV_max and TLr and compared them to Deauville score (DS) after two and four cycles chemotherapy (PET2 and PET4 respectively) and at the end of treatment PET (PETeot) on a cohort of 362 patients. TLr showed better diagnostic performances than DS for predicting 5-year progression-free survival (PFS), especially on early PET/CT assessments. Positive predictive values at PET2 for TLr, ΔSUV_max and DS were 51%, 34% and 31% respectively. On the multivariable analysis, significant predictive factors of PFS were TLr (at PET2, PET4 and PETeot) and ΔSUV_max (at PET4 and PETeot). DS was not significantly associated with PFS at any PET timing.

Statistical Challenges in Development of Prognostic Models in Diffuse Large B-Cell Lymphoma: Comparison Between Existing Models - A Systematic Review

Background and Aim

Based on advances in the diagnosis, classification, and management of diffuse large B-cell lymphoma (DLBCL), a number of new prognostic models have been proposed. The aim of this study was to review and compare different prognostic models of DLBCL based on the statistical methods used to evaluate the performance of each model, as well as to analyze the possible limitations of the methods.

Methods and Results

A literature search identified 46 articles that proposed 55 different prognostic models for DLBCL by combining different clinical, laboratory, and other parameters of prognostic significance. In addition, six studies used nomograms, which avoid risk categorization, to create prognostic models. Only a minority of studies assessed discrimination and/or calibration to compare existing models built upon different statistical methods in the process of development of a new prognostic model. All models based on nomograms reported the c-index as a measure of discrimination. There was no uniform evaluation of the performance in other prognostic models. We compared these models of DLBCL by calculating differences and ratios of 3-year overall survival probabilities between the high- and the low-risk groups. We found that the highest and lowest ratio between low- and high-risk groups was 6 and 1.31, respectively, while the difference between these groups was 18.9% and 100%, respectively. However, these studies had limited duration of follow-up and the number of patients ranged from 71 to 335.

Conclusion

There is no universal statistical instrument that could facilitate a comparison of prognostic models in DLBCL. However, when developing a prognostic model, it is recommended to report its discrimination and calibration in order to facilitate comparisons between different models. Furthermore, prognostic models based on nomograms are becoming more appealing owing to individualized disease-related risk estimations. However, they have not been validated yet in other study populations.

Interim PET Evaluation in Diffuse Large B-Cell Lymphoma Using Published Recommendations: Comparison of the Deauville 5-Point Scale and the ΔSUVmax Method

The value of interim ¹⁸F-FDG PET/CT (iPET)-guided treatment decisions in patients with diffuse large B-cell lymphoma (DLBCL) has been the subject of much debate. This investigation focuses on a comparison of the Deauville score and the change-in-SUV_max (ΔSUV_max) approach-2 methods to assess early metabolic response to standard chemotherapy in DLBCL. Methods: Of 609 DLBCL patients participating in the PET-Guided Therapy of Aggressive Non-Hodgkin Lymphomas trial, iPET scans of 596 patients originally evaluated using the ΔSUV_max method were available for post hoc assessment of the Deauville score. A commonly used definition of an unfavorable iPET result according to the Deauville score is an uptake greater than that of the liver, whereas an unfavorable iPET scan with regard to the ΔSUV_max approach is characterized as a relative reduction of the SUV_max between baseline and iPET staging of less than or equal to 66%. We investigated the 2 methods' correlation and concordance by Spearman rank correlation coefficient and the agreement in classification, respectively. We further used Kaplan-Meier curves and Cox regression to assess differences in survival between patient subgroups defined by the prespecified cutoffs. Time-dependent receiver-operating-characteristic curve analysis provided information on the methods' respective discrimination performance. Results: Deauville score and ΔSUV_max approach differed in their iPET-based prognosis. The ΔSUV_max approach outperformed the Deauville score in terms of discrimination performance-most likely because of a high number of false-positive decisions by the Deauville score. Cutoff-independent discrimination performance remained low for both methods, but cutoff-related analyses showed promising results. Both favored the ΔSUV_max approach, for example, for the segregation by iPET response, where the event-free survival hazard ratio was 3.14 (95% confidence interval, 2.22-4.46) for ΔSUV_max and 1.70 (95% confidence interval, 1.29-2.24) for the Deauville score. Conclusion: When considering treatment intensification, the currently used Deauville score cutoff of an uptake above that of the liver seems to be inappropriate and associated with potential harm for DLBCL patients. The ΔSUV_max criterion of a relative reduction in SUV_max of less than or equal to 66% should be considered as an alternative.