An international confirmatory study of the prognostic value of early PET/CT in diffuse large B-cell lymphoma: comparison between Deauville criteria and ΔSUVmax

Indicators describing the tumor lesion aggregation and dissemination and their impact on the prognosis of patients with diffuse large B cell lymphoma receiving chimeric antigen receptor T cell therapy

INTRODUCTION

Chimeric antigen receptor (CAR) T cell therapy has markedly improved the prognosis of patients with diffuse large B-cell lymphoma (DLBCL). The relative positioning of tumor lesions in lymphoma varies among patients, manifesting as either aggregation (clumped together) or dissemination (spread throughout the body). Prognostic significance of factors indicating the relative positioning of tumor lesions in CAR T cell therapy remains underexplored. For aggregation, prior research proposed the tumor volume surface ratio (TVSR), linking it to prognosis in chemotherapy. Regarding dissemination, indicators such as disease stage or extranodal involvement, commonly used in clinical practice, have not demonstrated prognostic significance in CAR T cell therapy. This study aims to analyze current indicators of tumor aggregation or dissemination and introduce a novel indicator to assess the prognostic value of tumor lesions' relative positioning in DLBCL patients undergoing CAR T cell therapy.

METHODS

This retrospective study included 42 patients receiving CAR T cell therapy. Lesion image information was obtained from the last PET/CT scan prior to CAR T cell infusion, including total metabolic tumor volume, total tumor surface, diameter of lymphoma masses, and the sites of tumor lesions. We evaluated TVSR and bulky disease as descriptors of tumor aggregation. We refined existing indicators, stage III&IV and >1 site extranodal involvement, to distill a new indicator, termed 'extra stage', to better represent tumor dissemination. The study examined the prognostic significance of tumor aggregation and dissemination.

RESULTS

Our findings indicate that TVSR, while prognostically valuable in chemotherapy, lacks practical prognostic value in CAR T cell therapy. Conversely, bulky disease emerged as an optimal prognostic indicator of tumor aggregation. Both bulky disease and extra stage were associated with poor prognosis and exhibiting synergistic prognostic impact in CAR T cell therapy.

CONCLUSIONS

Overall, the relative positioning of tumor lesions significantly influences the prognosis of patients with DLBCL receiving CAR T cell therapy. The ideal scenario involves tumors with minimal dissemination and no aggregation.

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.

Validation of the ΔSUVmax for Interim PET Interpretation in Diffuse Large B-Cell Lymphoma on the Basis of the GAINED Clinical Trial

The GAINED phase 3 trial (ClinicalTrials.gov identifier: NCT01659099) evaluated a PET-driven consolidative strategy in patients with diffuse large B-cell lymphoma. In this post hoc analysis, we aimed to compare the prognostic value of the per-protocol PET interpretation criteria (Menton 2011 consensus) with the change in the SUVmax (ΔSUVmax) alone. Methods: Real-time central review of 18F-FDG PET/CT was performed in 581 patients after 2 cycles (PET2) and 4 cycles (PET4) of immunochemotherapy using the Menton 2011 criteria, combining the ΔSUVmax (cutoffs of 66% and 70% at PET2 and PET4, respectively) and the Deauville scale. In "special cases," when the baseline SUVmax was less than 10.0 or the interim residual tumor SUVmax was greater than 5.0, the Menton 2011 experts' consensus agreed that the ΔSUVmax may not be reliable and that the Deauville score is preferable. Prognostic values of Menton 2011 and ΔSUVmax were evaluated by Kaplan-Meier analyses in terms of progression-free survival (PFS). Results: Seventeen percent of patients at PET2 (100/581) and 8% at PET4 (49/581) had PET-negative results by ΔSUVmax but were considered to have PET-positive results according to Menton 2011 with residual SUVmax of greater than 5.0. For the population with PET2-positive results, 2-y PFS was 70% (range, 58%-80%) with ΔSUVmax alone, whereas the outcome tended to be better for those who were considered to have PET-positive results by Menton 2011, 81% (range, 72%-87%). Conversely, all 10 patients with baseline SUVmax of less than 10.0 had PET2-positive results by ΔSUVmax but were considered to have PET2-negative results by Menton 2011. These patients had the same 2-y PFS as patients with PET2-negative/PET4-negative results, indicating that the ΔSUVmax yielded false-positive results in this situation. Conclusion: We recommend the use of the ΔSUVmax alone rather than the Menton 2011 criteria for assessing the interim metabolic response in patients with diffuse large B-cell lymphoma, except when the baseline SUVmax is less than 10.0.

A Review on the Use of Imaging Biomarkers in Oncology Clinical Trials: Quality Assurance Strategies for Technical Validation

Imaging biomarkers (IBs) have been proposed in medical literature that exploit images in a quantitative way, going beyond the visual assessment by an imaging physician. These IBs can be used in the diagnosis, prognosis, and response assessment of several pathologies and are very often used for patient management pathways. In this respect, IBs to be used in clinical practice and clinical trials have a requirement to be precise, accurate, and reproducible. Due to limitations in imaging technology, an error can be associated with their value when considering the entire imaging chain, from data acquisition to data reconstruction and subsequent analysis. From this point of view, the use of IBs in clinical trials requires a broadening of the concept of quality assurance and this can be a challenge for the responsible medical physics experts (MPEs). Within this manuscript, we describe the concept of an IB, examine some examples of IBs currently employed in clinical practice/clinical trials and analyze the procedure that should be carried out to achieve better accuracy and reproducibility in their use. We anticipate that this narrative review, written by the components of the EFOMP working group on "the role of the MPEs in clinical trials"-imaging sub-group, can represent a valid reference material for MPEs approaching the subject.

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.

Efficacy and safety of zanubrutinib plus R-CHOP in treatment of non-GCB DLBCL with extranodal involvement

Introduction

Treatment with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) shows poor response rates in non-germinal center B cell-like (non-GCB) diffuse large B-cell lymphoma (DLBCL) patients with multiple extranodal involvement. This study aims to evaluate anti-tumor activity and safety of zanubrutinib with R-CHOP (ZR-CHOP) in treatment naïve non-GCB DLBCL with extranodal involvement.

Methods

In this single-arm, phase 2, prospective, single-center study, patients with newly diagnosed non-GCB DLBCL with extranodal involvement enrolled between October 2020 to March 2022 received ZR-CHOP for 6 cycles followed by 2 cycles of maintenance treatment with rituximab and zanubrutinib. The primary endpoint included progression-free survival (PFS) in the intent-to-treat (ITT) population whereas the secondary endpoints included overall response rate (ORR), complete response (CR), and duration of response. Further, next-generation sequencing (NGS) was used for detection of different oncogenic mutations closely related to DLBCL pathogenesis.

Results

From October 2020 to March 2022, 26 patients were enrolled, and 23 of them were evaluated for efficacy after receiving 3 cycles of ZR-CHOP treatment. 1-year PFS and OS were 80.8% and 88.5% respectively while expected PFS and OS for 2-years are 74.0% and 88.5% respectively with median follow-up of 16.7 months and ORR was 91.3% (CR: 82.61%; PR: 8.70%). Oncogenic mutations closely related to DLBCL pathogenesis were assessed in 20 patients using NGS. B-cell receptor and NF-κB pathway gene mutations were detected in 10 patients, which occurred in MYD88 (7/19), CD79B (4/19), CARD11 (5/19), and TNFAIP3 (2/19). Hematological adverse events (AEs) ≥ grade 3 included neutropenia (50%), thrombocytopenia (23.1%), and anemia (7.7%) whereas non-hematological AEs ≥ grade 3 included pulmonary infection (19.2%).

Conclusion

ZR-CHOP is safe and effective for treating treatment naïve non-GCB DLBCL patients with extranodal involvement.

Clinical Trial Registration

Clinicaltrials.gov, NCT04835870.

Interim FDG-PET/CT for Response Assessment of Lymphoma

The clinical use and prognostic value of interim FDG-PET/CT (iPET/CT), which is performed after treatment initiation but prior to its completion, varies by lymphoma subtype. Evidence supporting the prognostic value of iPET/CT is more robust for classical Hodgkin lymphoma (cHL), and in this lymphoma subtype, response-adapted treatment approaches guided by iPET/CT are a widely used standard of care for first-line therapy. The data supporting use of iPET/CT among patients with non-Hodgkin lymphoma (NHL) is less well-established, but failure to achieve complete metabolic response on iPET/CT is generally considered a poor prognostic factor with likely consequences for progression free survival. This review will present the available evidence supporting use of iPET/CT in lymphoma patients, particularly as it relates to prognostication and the ability to inform response-adapted treatment strategies. The latter will be addressed through a discussion on the major iPET-response adapted clinical trials with mention of ongoing trials. Special attention will be given to cHL and a few subtypes of NHL, including diffuse large B cell lymphoma (DLBCL), follicular lymphoma (FL), and peripheral T cell lymphoma (PTCL).

Role of 18F-fluorodeoxyglucose PET/computed tomography in the diagnosis and treatment response assessment of primary bone lymphoma

OBJECTIVE

Primary bone lymphoma (PBL) is a rare type of extranodal lymphoma, and the clinical application value of 18F-fluorodeoxyglucose PET/computed tomography ( 18 F-FDG PET/CT) in PBL has not been fully evaluated. This study aimed to determine the imaging characteristics of PBL and investigate the value of 18 F-FDG PET/CT parameters.

METHODS

A total of 25 patients with PBL who underwent PET/CT examination before treatment were included in this study. The clinicopathological parameters and PET/CT parameters were analyzed.

RESULTS

Among the 25 patients, 7 patients had single lesions, 15 patients had nonsingle lesions (≥2) and 3 patients had diffuse distribution in the medullary cavity. The bone destruction types included osteolytic, osteogenic, normal density, mixed lytic and osteogenic. All patients showed increased FDG uptake, and the CT detection rate was 88%. Five patients underwent PET/CT assessment mid-treatment, and when assessed using the Deauville five-point scale, four patients were PET-negative and one patient was PET-positive. There were two PET-positive and three PET-negative patients when assessed using the Δ maximum standardized uptake value (SUV max ) method. Six patients underwent PET/CT imaging at the end of treatment. When assessed using the Deauville five-point scale, five patients (83%) were PET-negative and one patient (17%) was PET-positive. The same results were obtained when evaluated by the ΔSUV max method.

CONCLUSION

PET/CT plays a substantial role in the diagnosis and treatment efficacy evaluation of PBL, and it should be recognized by clinicians and radiologists. Changes in metabolic parameters such as SUV, metabolic tumor volume and total lesion glycolysis have considerable potential for application in PBL diagnostics and treatment efficacy evaluation.

Is local review of positron emission tomography scans sufficient in diffuse large B-cell lymphoma clinical trials? A CALGB 50303 analysis

BACKGROUND

Quantitative methods of Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) interpretation, including the percent change in FDG uptake from baseline (ΔSUV), are under investigation in lymphoma to overcome challenges associated with visual scoring systems (VSS) such as the Deauville 5-point scale (5-PS).

METHODS

In CALGB 50303, patients with DLBCL received frontline R-CHOP or DA-EPOCH-R, and although there were no significant associations between interim PET responses assessed centrally after cycle 2 (iPET) using 5-PS with progression-free survival (PFS) or overall survival (OS), there were significant associations between central determinations of iPET ∆SUV with PFS/OS. In this patient cohort, we retrospectively compared local vs central iPET readings and evaluated associations between local imaging data and survival outcomes.

RESULTS

Agreement between local and central review was moderate (kappa = 0.53) for VSS and high (kappa = 0.81) for ∆SUV categories (<66% vs. ≥66%). ∆SUV ≥66% at iPET was significantly associated with PFS (p = 0.03) and OS (p = 0.002), but VSS was not. Associations with PFS/OS when applying local review vs central review were comparable.

CONCLUSIONS

These data suggest that local PET interpretation for response determination may be acceptable in clinical trials. Our findings also highlight limitations of VSS and call for incorporation of more objective measures of response assessment in clinical trials.

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.

Biology-Guided Radiation Therapy

Biology-guided radiation therapy is an emerging field whereby delivery of external beam radiotherapy incorporates biological/molecular imaging to inform radiation treatment. At present, there is evidence for the use of functional imaging such as PET to evaluate treatment response in patients both during and after radiation treatment as well as to provide a method of adapting or selecting patient-specific treatments. Examples in thoracic, gastrointestinal, and hematologic malignancies are provided. Improvements in PET metrics, thresholds, and novel radiotracers will further move this novel field forward.

Application of the Lugano Classification for Initial Evaluation, Staging, and Response Assessment of Hodgkin and Non-Hodgkin Lymphoma: The PRoLoG Consensus Initiative (Part 2-Technical)

The aim of this initiative was to provide consensus recommendations from a consortium of academic and industry experts in the field of lymphoma and imaging for the consistent application of imaging assessment with the Lugano classification. Methods: Consensus was obtained through a series of meetings from July 2019 to October 2021 sponsored by the PINTaD (Pharma Imaging Network for Therapeutics and Diagnostics) as part of the ProLoG (PINTaD RespOnse criteria in Lymphoma wOrking Group) consensus initiative. Results: Consensus recommendations encompass all technical imaging aspects of the Lugano classification. Some technical considerations for PET/CT and diagnostic CT are clarified with regards to required imaging series and scan visits, as well as acquisition and reconstruction of PET images and influence of lesion size and background activity. Recommendations are given on the role of imaging and clinical reviewers as well as on training and monitoring. Finally, an example template of an imaging case report form is provided to support efficient collection of data with Lugano Classification. Conclusion: Consensus recommendations are made to comprehensively address technical and imaging areas of inconsistency and ambiguity in the classification encountered by end users. Such guidance should be used to support standardized acquisition and evaluation with the Lugano 2014.

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.

Validation of Deauville Score for Response Evaluation in Hodgkin's Lymphoma

Context

Positron emission tomography (PET) using F-18 fluorodeoxyglucose (FDG) for treatment monitoring in patients with lymphoma is one of the most well-developed clinical applications. Deauville five-point score (DS) is recommended for response assessment in international guidelines. DS gives the threshold for adequate or inadequate response to be adapted according to the clinical context or research question.

Aims

We aimed to validate DS in Hodgkin's lymphoma (HL) by retrospectively assigning this score to F-18 FDG PET-computed tomography (CT) studies done before 2016 and analyzing its concordance with the line of management. The secondary aim was to assess the reproducibility of DS in the interpretation of PET-CT scans.

Subjects and Methods

A total of 100 eligible consecutive patients underwent F-18 FDG PET-CT scans between January 2014 and December 2015. Their interim, end of treatment, and follow-up PET scans were retrospectively visually analyzed and assigned DS by three nuclear medicine physicians. Concordance was defined as agreement between the DS assigned and the line of treatment. Interobserver variability was calculated using weighted Kappa and presented with 95% confidence interval.

Results

Among 212 scans assigned DS, 165 scans showed agreement between the DS and line of treatment. Of these, 95.2% of scans scored DS 1-3 were kept on following or the same treatment plan was continued and patients did well. Among the scans that showed discordance, 24 scans scored DS 4/5 were continued on the same treatment regimen and the next assessment showed disease progression.

Conclusions

Our study confirmed that DS is a useful tool to aid in reporting F-18 FDG PET-CT in the management of HL with good positive and negative predictive values. This study also demonstrated good interobserver agreement.

Determining the suitability of definitive radiation therapy in patients with metastatic nasopharyngeal carcinoma based on PET/CT: a large cohort study

OBJECTIVES

To determine patients with de novo metastatic nasopharyngeal carcinoma (mNPC) who would benefit from receiving definitive radiation therapy (DRT) along with their pre-existing palliative chemotherapy (PCT) by evaluating their post-PCT Deauville scores and EBV DNA.

METHODS

A total of 570 mNPC patients, treated with PCT or PCT+DRT, were studied. EBV DNA levels, along with post-PCT Deauville scores, were used to stratify risk based on the recursive partitioning analysis (RPA).

RESULTS

Significant differences were observed in the survival rates of patients with Deauville scores of 1-3 and 4-5 (2-year progression-free survival (PFS): 23.4% versus 8.5%, p < 0.001; 2-year overall survival (OS): 56.8% versus 18.8%, p < 0.001). RPA yielded three distinct groups in the increasing order of risk (Deauville scores of all RPA I-II were within the range of 1-3): (1) RPA I: EBV DNA levels at a pretreatment concentration ≤ 4000 copies/mL and undetectable post-PCT; (2) RPA II: EBV DNA levels either at a pretreatment concentration > 4000 copies/mL or at a pretreatment concentration ≤ 4000 copies/mL and detectable post-PCT; (3) RPA III: Deauville scores 4-5. While patients in RPA I and RPA II had significantly PFS rates when treated with PCT+DRT than when treated with PCT alone (RPA I: 72.7% versus 13.4%, RPA II: 37.8% versus 6.3%), those in RPA III did not experience such PFS benefits (6.5% versus 9.7%).

CONCLUSION

PCT+DRT might improve the survival rates in mNPC patients in the low- and mid-risk strata but not those of patients in the high-risk strata.

KEY POINTS

We use the Deauville scores and the concentrations of the Epstein-Barr virus (EBV) DNA to determine those patients with de novo metastatic NPC who would benefit from radiation therapy.

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.

Risk Assessment in Diffuse Large B-Cell Lymphoma by Combining Baseline Metabolic Tumor Volume and Peking Criteria When Evaluating Series 18F-Fluorodeoxyglucose Positron Emission Tomography Scans

This study aimed to determine the predictive and prognostic value of baseline metabolic tumor volume (MTV) and the Peking criteria from serial positron emission tomography (PET) scans in diffuse large B-cell lymphoma, including 300 newly diagnosed patients who were prospectively treated with 2–4 cycles of standard first-line treatment (clinicaltrials.gov identifier: NCT02928861). PET/computed tomography (CT) examinations were performed at baseline, after two (PET-2) or four cycles (PET-4). PET during the interim was evaluated using Deauville 5-point scales (5-PS), ΔSUV_max criteria, and the Peking criteria which interpreted based on the maximum standard uptake of the liver (SUV_max-liver). Peking criteria had better accuracy, positive predictive value (PPV), and specificity than other two methods. The MTV and Peking criteria both significantly predicted progression-free survival (PFS) and overall survival (OS). An MTV > 191 cm² and Peking criteria of PET-2 and PET-4 > 1.6-fold SUV_max-liver was used as the cutoff for a positive result. PET-4 achieved higher accuracy, PPV, and specificity for 2-year PFS (83.3%, 86.7%, and 98.4%, respectively) and OS (92.6%, 73.3%, and 97.2%, respectively) than PET-2. Various prognostic models containing different risk factors were established via Cox regression analysis. The MTV and PET-2/PET-4 results were used to categorized patients into low-risk, intermediate-risk, and high-risk prognostic groups (with 0, 1, and 2 risk factors, respectively) (P < 0.0001). High burden MTV and positive PET-2 and PET-4 (>1.6-fold SUV_max-liver) could identify high-risk patients with 2-year PFS and OS of 0.0% and 26.3% (95% confidence interval [CI]: N/A to 54.3%). When PET-2 and PET-4 were evaluated by 5-PS, the 2-year PFS and OS from high risk patients of three-parameters model achieved 31.4% (95%CI: 6.9%–55.9%) and 42.7% (95%CI: 14.6%–70.7%). In conclusion, combining baseline MTV and any regular response on PET/CT evaluated using the Peking criteria can improve prognostic value. Serial PET/CT from baseline MTV to PET-4 may have relatively greater predictive power for poor prognosis in diffuse large B-cell lymphoma.

Application of 18F-FDG PET-CT Images Based Radiomics in Identifying Vertebral Multiple Myeloma and Bone Metastases

Purpose

The purpose of this study was to explore the application of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) image radiomics in the identification of spine multiple myeloma (MM) and bone metastasis (BM), and whether this method could improve the classification diagnosis performance compared with traditional methods.

Methods

This retrospective study collected a total of 184 lesions from 131 patients between January 2017 and January 2021. All images were visually evaluated independently by two physicians with 20 years of experience through the double-blind method, while the maximum standardized uptake value (SUVmax) of each lesion was recorded. A total of 279 radiomics features were extracted from the region of interest (ROI) of CT and PET images of each lesion separately by manual method. After the reliability test, the least absolute shrinkage and selection operator (LASSO) regression and 10-fold cross-validation were used to perform dimensionality reduction and screening of features. Two classification models of CT and PET were derived from CT images and PET images, respectively and constructed using the multivariate logistic regression algorithm. In addition, the ComModel was constructed by combining the PET model and the conventional parameter SUVmax. The performance of the three classification diagnostic models, as well as the human experts and SUVmax, were evaluated and compared, respectively.

Results

A total of 8 and 10 features were selected from CT and PET images for the construction of radiomics models, respectively. Satisfactory performance of the three radiomics models was achieved in both the training and the validation groups (Training: AUC: CT: 0.909, PET: 0.949, ComModel: 0.973; Validation: AUC: CT: 0.897, PET: 0.929, ComModel: 0.948). Moreover, the PET model and ComModel showed significant improvement in diagnostic performance between the two groups compared to the human expert (Training: P = 0.01 and P = 0.001; Validation: P = 0.018 and P = 0.033), and no statistical difference was observed between the CT model and human experts (P = 0.187 and P = 0.229, respectively).

Conclusion

The radiomics model constructed based on 18F-FDG PET/CT images achieved satisfactory diagnostic performance for the classification of MM and bone metastases. In addition, the radiomics model showed significant improvement in diagnostic performance compared to human experts and PET conventional parameter SUVmax.

Axicabtagene ciloleucel as first-line therapy in high-risk large B-cell lymphoma: the phase 2 ZUMA-12 trial

High-risk large B-cell lymphoma (LBCL) has poor outcomes with standard first-line chemoimmunotherapy. In the phase 2, multicenter, single-arm ZUMA-12 study (ClinicalTrials.gov NCT03761056) we evaluated axicabtagene ciloleucel (axi-cel), an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, as part of first-line treatment in 40 patients with high-risk LBCL. This trial has completed accrual. The primary outcome was complete response rate (CRR). Secondary outcomes were objective response rate (ORR), duration of response (DOR), event-free survival (EFS), progression-free survival (PFS), overall survival (OS), assessment of safety, central nervous system (CNS) relapse and blood levels of CAR T cells and cytokines. The primary endpoint in efficacy-evaluable patients (n = 37) was met, with 78% CRR (95% confidence interval (CI), 62-90) and 89% ORR (95% CI, 75-97). As of 17 May 2021 (median follow-up, 15.9 months), 73% of patients remained in objective response; median DOR, EFS and PFS were not reached. Grade ≥3 cytokine release syndrome (CRS) and neurologic events occurred in three patients (8%) and nine patients (23%), respectively. There were no treatment-related grade 5 events. Robust CAR T-cell expansion occurred in all patients with a median time to peak of 8 days. We conclude that axi-cel is highly effective as part of first-line therapy for high-risk LBCL, with a manageable safety profile.

Lesion-Based Radiomics Signature in Pretherapy 18F-FDG PET Predicts Treatment Response to Ibrutinib in Lymphoma

PURPOSE

The aim of this study was to develop a pretherapy PET/CT-based prediction model for treatment response to ibrutinib in lymphoma patients.

PATIENTS AND METHODS

One hundred sixty-nine lymphoma patients with 2441 lesions were studied retrospectively. All eligible lymphomas on pretherapy 18F-FDG PET images were contoured and segmented for radiomic analysis. Lesion- and patient-based responsiveness to ibrutinib was determined retrospectively using the Lugano classification. PET radiomic features were extracted. A radiomic model was built to predict ibrutinib response. The prognostic significance of the radiomic model was evaluated independently in a test cohort and compared with conventional PET metrics: SUVmax, metabolic tumor volume, and total lesion glycolysis.

RESULTS

The radiomic model had an area under the receiver operating characteristic curve (ROC AUC) of 0.860 (sensitivity, 92.9%, specificity, 81.4%; P < 0.001) for predicting response to ibrutinib, outperforming the SUVmax (ROC AUC, 0.519; P = 0.823), metabolic tumor volume (ROC AUC, 0.579; P = 0.412), total lesion glycolysis (ROC AUC, 0.576; P = 0.199), and a composite model built using all 3 (ROC AUC, 0.562; P = 0.046). The radiomic model increased the probability of accurately predicting ibrutinib-responsive lesions from 84.8% (pretest) to 96.5% (posttest). At the patient level, the model's performance (ROC AUC = 0.811; P = 0.007) was superior to that of conventional PET metrics. Furthermore, the radiomic model showed robustness when validated in treatment subgroups: first (ROC AUC, 0.916; P < 0.001) versus second or greater (ROC AUC, 0.842; P < 0.001) line of defense and single treatment (ROC AUC, 0.931; P < 0.001) versus multiple treatments (ROC AUC, 0.824; P < 0.001).

CONCLUSIONS

We developed and validated a pretherapy PET-based radiomic model to predict response to treatment with ibrutinib in a diverse cohort of lymphoma patients.

Phase 1 study of oral azacitidine (CC-486) plus R-CHOP in previously untreated intermediate- to high-risk DLBCL

Resistance to standard immunochemotherapy remains an unmet challenge in diffuse large B-cell lymphoma (DLBCL), and aberrant DNA methylation may contribute to chemoresistance. Promising early-phase results were reported with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) plus subcutaneous azacitidine, a hypomethylating agent. In this phase 1 study, we evaluated CC-486 (oral azacitidine) plus 6 cycles of R-CHOP in patients with previously untreated intermediate- to high-risk DLBCL or grade 3B/transformed follicular lymphoma. CC-486 doses of 100, 150, 200, or 300 mg given 7 days before cycle 1 and on days 8-21 of cycles 1-5 were evaluated; additional patients were enrolled in the expansion phase to examine preliminary efficacy. The primary objectives were to determine the safety and the maximum tolerated dose (MTD) of CC-486 in combination with R-CHOP. The most common grade 3/4 toxicities were hematologic, including neutropenia (62.7%) and febrile neutropenia (25.4%); grade 3/4 nonhematologic toxicities were uncommon (<7%). The MTD was not established; 2 patients had dose-limiting toxicities (1 with grade 4 febrile neutropenia; 1 with grade 4 prolonged neutropenia). The recommended phase 2 dose was established as 300 mg. The overall response rate was 94.9%, with 52 patients (88.1%) achieving complete responses. With a median follow-up of 28.9 months, estimated 1- and 2-year progression-free survival rates were 84.1% and 78.6%, respectively. Overall, epigenetic priming with CC-486 before R-CHOP can be delivered with acceptable safety to patients with previously untreated intermediate- to high-risk DLBCL or grade 3B/transformed follicular lymphoma. ClinicalTrials.gov: NCT02343536.

A review on advances in 18F-FDG PET/CT radiomics standardisation and application in lung disease management

Radiomics analysis quantifies the interpolation of multiple and invisible molecular features present in diagnostic and therapeutic images. Implementation of 18-fluorine-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) radiomics captures various disorders in non-invasive and high-throughput manner. ¹⁸F-FDG PET/CT accurately identifies the metabolic and anatomical changes during cancer progression. Therefore, the application of ¹⁸F-FDG PET/CT in the field of oncology is well established. Clinical application of ¹⁸F-FDG PET/CT radiomics in lung infection and inflammation is also an emerging field. Combination of bioinformatics approaches or textual analysis allows radiomics to extract additional information to predict cell biology at the micro-level. However, radiomics texture analysis is affected by several factors associated with image acquisition and processing. At present, researchers are working on mitigating these interrupters and developing standardised workflow for texture biomarker establishment. This review article focuses on the application of ¹⁸F-FDG PET/CT in detecting lung diseases specifically on cancer, infection and inflammation. An overview of different approaches and challenges encountered on standardisation of ¹⁸F-FDG PET/CT technique has also been highlighted. The review article provides insights about radiomics standardisation and application of ¹⁸F-FDG PET/CT in lung disease management.

One-stop local and whole-body staging of children with cancer

Accurate staging and re-staging of cancer in children is crucial for patient management. Currently, children with a newly diagnosed cancer must undergo a series of imaging tests, which are stressful, time-consuming, partially redundant, expensive, and can require repetitive anesthesia. New approaches for pediatric cancer staging can evaluate the primary tumor and metastases in a single session. However, traditional one-stop imaging tests, such as CT and positron emission tomography (PET)/CT, are associated with considerable radiation exposure. This is particularly concerning for children because they are more sensitive to ionizing radiation than adults and they live long enough to experience secondary cancers later in life. In this review article we discuss child-tailored imaging tests for tumor detection and therapy response assessment - tests that can be obtained with substantially reduced radiation exposure compared to traditional CT and PET/CT scans. This includes diffusion-weighted imaging (DWI)/MRI and integrated [F-18]2-fluoro-2-deoxyglucose (18F-FDG) PET/MRI scans. While several investigators have compared the value of DWI/MRI and 18F-FDG PET/MRI for staging pediatric cancer, the value of these novel imaging technologies for cancer therapy monitoring has received surprisingly little attention. In this article, we share our experiences and review existing literature on this subject.

Prognostic value of interim FDG PET-CT in patients older than 60 years with diffuse large B-cell lymphoma treated by PMitCEBO plus rituximab. Comparison between Deauville 5-point scale and International Harmonization Project criteria

BACKGROUND

Advanced age is an independent poor prognostic factor of diffuse large B-cell lymphoma (DLBCL). PMitCEBO (mitoxantrone, cyclophosphamide, etoposide, vincristine, bleomycin, and prednisolone) is an alternative to the cyclophosphamide, doxorubicin, vincristine, and prednisolone regimen to decrease side effects in elderly patients. Many studies have shown prognostic value of an interim FDG PET-CT to predict survival. A recent consensus (ICML, Lugano 2013) has suggested using the 5-point scale Deauville criteria instead of those of the International Harmonization Project (IHP) to visually assess the response on interim PET. The objective of this study was to evaluate the prognostic value of an interim FDG PET-CT in patients older than 60 with treated DLBCL and to compare IHP and 5-PS Deauville visual interpretation to predict survival.

METHODS

Forty-eight patients (mean age 73.2±5.2 years) treated by R-PMitCEBO for DLBCL undergoing FDG PET-CT before and after 3 cycles of treatment were retrospectively included. Event-free survival and overall survival were determined by Kaplan-Meier method and compared with interim PET-CT results using IHP and 5-PS Deauville criteria.

RESULTS

Interim PET results using 5-PS Deauville criteria were significantly correlated with EFS (P<0.0001) and OS (P=0.001) whereas they were moderately correlated with EFS (P=0.046) and not with OS (P=0.106) using IHP criteria. Two-year EFS and OS rates were 86.5% and 89.2%, respectively, for patients in 1-3 score group, and 27.3% and 36.4%, respectively, for patients in ≥4 score group using the Deauville criteria.

CONCLUSIONS

Our results confirmed the prognostic value of an interim PET-CT in elderly patients with DLBCL and the better performance of the 5-PS Deauville criteria.

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.

Prognostication of diffuse large B-cell lymphoma patients with Deauville score of 3 or 4 at end-of-treatment PET evaluation: a comparison of the Deauville 5-point scale and the ΔSUVmax method

Diffuse large B-cell lymphoma is treated with anti-CD 20 and multi-drug chemotherapy for cure. Positron emission tomography (PET) scans are performed at end of treatment (EOT) to assess response. EOT Deauville scores (DS) are equivocal for treatment response in some situations, requiring physicians to determine the need for further investigations or treatment. Studies have suggested the delta maximum standardised uptake value (ΔSUVmax) to be superior to DS for assessment of metabolic response at interim PET, although its use at EOT PET, especially in cases of equivocal response, has yet to be established. We investigated whether ΔSUVmax could better discriminate prognosis than DS 3 or 4 at EOT. ΔSUVmax did not outperform DS. Combination of DS 3 and International Prognostic Index (IPI) <3 selects for patients with extremely low risk of disease progression (HR 0.06, 95% CI 0.01 to 0.62, p 0.018) compared to DS 4 and IPI ≥3.

FDG-PET/CT in Lymphoma: Where Do We Go Now?

18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) is an essential part of the management of patients with lymphoma at staging and response evaluation. Efforts to standardize PET acquisition and reporting, including the 5-point Deauville scale, have enabled PET to become a surrogate for treatment success or failure in common lymphoma subtypes. This review summarizes the key clinical-trial evidence that supports PET-directed personalized approaches in lymphoma but also points out the potential place of innovative PET/CT metrics or new radiopharmaceuticals in the future.

A prospective study on early PET/CT scans during the first cycle of salvage chemotherapy for relapsed or refractory diffuse large B-cell lymphoma

Many patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) will not respond to platinum-containing salvage chemotherapy. Predicting treatment failure earlier could help clinicians minimize chemotherapy toxicities for non-responders in favor of other treatments. We conducted a pilot study where 2 early PET/CTs were obtained on days 4 (D4) and 21 (D21) of cycle 1 (C1) of salvage therapy for DLBCL. Twenty-five patients were enrolled and have evaluable data. Ten (40%) had an unplanned therapy change after C1 and before end-of-treatment (EOT) evaluation due to treatment failure on early PET/CT as interpreted by the treating physician. Early PET/CT response at D4 or D21 was not associated with EOT response in evaluable patients. Disease specific survival was longer for patients with a persistent response on both D4 and D21 (p = 0.042). Early PET/CT may predict salvage chemotherapy failure and could inform future clinical trials investigating early therapy change to non-chemotherapy treatments.

PET Imaging for Hematologic Malignancies

Hematologic malignancies are a broad category of cancers arising from the lymphoid and myeloid cell lines. The 2016 World Health Organization classification system incorporated molecular markers as part of the diagnostic criteria and includes more than 100 subtypes. This article focuses on the subtypes for which imaging with positron emission tomography/computed tomography (PET/CT) has become an integral component of the patient's evaluation, that is, lymphoma and multiple myeloma. Leukemia and histiocytic and dendritic cell neoplasms are also discussed as these indications for PET/CT are less common, but increasingly seen in clinic.

Prognostic Impact of 18F-FDG PET/CT in Patients With Aggressive B-Cell Lymphoma Treated With Anti-CD19 Chimeric Antigen Receptor T Cells

PURPOSE OF THE REPORT

We aimed to evaluate the role of 18F-FDG PET/CT in predicting patient outcome following chimeric antigen receptor T (CAR T) cells infusion in aggressive B-cell lymphoma.

METHODS

18F-FDG PET/CT data before leukapheresis, before CAR T-cell infusion and 1 month (M1) after CAR T-cell infusion, from 72 patients were retrospectively analyzed. SUVmax, total lesion glycolysis (TLG), metabolic tumor volume (MTV), and parameters describing tumor kinetics were calculated for each 18F-FDG PET/CT performed. The aim was to evaluate the prognostic value of 18F-FDG PET/CT metabolic parameters for predicting progression-free survival (PFS) and overall survival (OS) following CAR T-cell therapy.

RESULTS

Regarding PFS, ∆MTVpre-CAR and ∆TLGpre-CAR were found to be more discriminating compared with metabolic parameters at preinfusion. Median PFS in patients with a ∆MTVpre-CAR of less than 300% was 6.8 months (95% confidence interval [CI], 2.8 months to not reached) compared with 2.8 months (95% CI, 0.9-3.0 months) for those with a value of 300% or greater (P = 0.004). Likewise, median PFS in patients with ∆TLGpre-CAR of less than 420% was 6.8 months (95% CI, 2.8 months to not reached) compared with 2.7 months (95% CI, 1.3-3.0 months) for those with a value of 420% or greater (P = 0.0148). Regarding OS, metabolic parameters at M1 were strongly associated with subsequent outcome. SUVmax at M1 with a cutoff value of 14 was the most predictive parameter in multivariate analysis, outweighing other clinicobiological variables (P < 0.0001).

CONCLUSIONS

Disease metabolic volume kinetics before infusion of CAR T cells seems to be superior to initial tumor bulk itself for predicting PFS. For OS, SUVmax at M1 might adequately segregate patients with different prognosis.

Positron emission tomography/computed tomography in the management of Hodgkin and B-cell non-Hodgkin lymphoma: An update

¹⁸ F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is now an integral part of lymphoma staging and management. Because of its greater accuracy compared with CT alone, PET/CT is currently routinely performed for staging and for response assessment at the end of treatment in the vast majority of FDG-avid lymphomas and is the cornerstone of response classification for these lymphomas according to the Lugano classification. Interim PET/CT, typically performed after 2 to 4 of 6 to 8 chemotherapy/chemoimmunotherapy cycles with or without radiation, is commonly performed for prognostication and potential treatment escalation or de-escalation early in the course of therapy, a concept known as response-adapted or risk-adapted treatment. Quantitative PET is an area of growing interest. Metrics, such as the standardized uptake value, changes (Δ) in the standardized uptake value, metabolic tumor volume, and total lesion glycolysis, are being investigated as more reproducible and potentially more accurate predictors of response and prognosis. Despite the progress made in standardizing the use of PET/CT in lymphoma, challenges remain, particularly with respect to its limited positive predictive value, emphasizing the need for more specific molecular probes. This review highlights the most relevant applications of PET/CT in Hodgkin and B-cell non-Hodgkin lymphoma, its strengths and limitations, as well as recent efforts at implementing PET/CT-based metrics as promising tools for precision medicine.

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.

A risk model for relapsed/refractory aggressive NHL integrating clinical risk factors and pretransplant Deauville score

There are limited data regarding the combined value of the pretransplant Deauville score (DS) from a positron emission tomography scan and clinical risk factors in patients with relapsed/refractory aggressive non-Hodgkin lymphoma (NHL). We performed a retrospective analysis to assess the prognostic role of pretransplant DS in patients with relapsed/refractory aggressive NHL who underwent salvage chemotherapy and autologous stem cell transplantation (ASCT). We identified 174 eligible patients between January 2013 and March 2019. In multivariable analysis, pretransplant DS, B symptoms, and secondary International Prognostic Index (sIPI) were independent risk factors for event-free survival (EFS). These variables were used to derive an integrated risk score that categorized 166 patients with available information for all risk factors into 3 groups: low (n = 92; 55.4%), intermediate (n = 48; 28.9%), and high (n = 26; 15.7%). The new prognostic index showed a strong association with EFS (low-risk vs intermediate-risk hazard ratio [HR], 3.94; 95% confidence interval [CI], 2.16-7.17; P < .001; low-risk vs high-risk HR, 10.83; 95% CI, 5.81-20.19; P < .001) and outperformed models based on clinical risk factors or DS alone. These results were validated in 60 patients from an independent external cohort (low-risk vs intermediate-risk HR, 4.04; 95% CI, 1.51-10.82; P = .005; low-risk vs high-risk HR, 10.49; 95% CI, 4.11-26.73; P < .001). We propose and validate a new prognostic index that risk-stratifies patients undergoing salvage chemotherapy followed by ASCT, thereby identifying patients at high risk for posttransplant treatment failure.

PET Molecular Imaging: A Holistic Review of Current Practice and Emerging Perspectives for Diagnosis, Therapeutic Evaluation and Prognosis in Clinical Oncology

PET/CT molecular imaging has been imposed in clinical oncological practice over the past 20 years, driven by its two well-grounded foundations: quantification and radiolabeled molecular probe vectorization. From basic visual interpretation to more sophisticated full kinetic modeling, PET technology provides a unique opportunity to characterize various biological processes with different levels of analysis. In clinical practice, many efforts have been made during the last two decades to standardize image analyses at the international level, but advanced metrics are still under use in practice. In parallel, the integration of PET imaging with radionuclide therapy, also known as radiolabeled theranostics, has paved the way towards highly sensitive radionuclide-based precision medicine, with major breakthroughs emerging in neuroendocrine tumors and prostate cancer. PET imaging of tumor immunity and beyond is also emerging, emphasizing the unique capabilities of PET molecular imaging to constantly adapt to emerging oncological challenges. However, these new horizons face the growing complexity of multidimensional data. In the era of precision medicine, statistical and computer sciences are currently revolutionizing image-based decision making, paving the way for more holistic cancer molecular imaging analyses at the whole-body level.

The effect of reduced scan time on response assessment FDG-PET/CT imaging using Deauville score in patients with lymphoma

PURPOSE

[18F]Fluoro-deoxy-glucose positron emission tomography/computed tomography (FDG-PET/CT) is used for response assessment during therapy in Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL). Clinicians report the scans visually using Deauville criteria. Improved performance in modern PET/CT scanners could allow for a reduction in scan time without compromising diagnostic image quality. Additionally, patient throughput can be increased with increasing cost-effectiveness. We investigated the effects of reducing scan time of response assessment FDG-PET/CT in HL and NHL patients on Deauville score (DS) and image quality.

METHODS

Twenty patients diagnosed with HL/NHL referred to a response assessment FDG-PET/CT were included. PET scans were performed in list-mode with an acquisition time of 120 s per bed position(s/bp). From PET list-mode data images with full acquisition time of 120 s/bp and shorter acquisition times (90, 60, 45, and 30 s/bp) were reconstructed. All images were assessed by two specialists and assigned a DS. We estimated the possible savings when reducing scan time using a simplified model based on assumed values/costs for our hospital.

RESULTS

There were no significant changes in the visually assessed DS when reducing scan time to 90 s/bp, 60 s/bp, 45 s/bp, and 30 s/bp. Image quality of 90 s/bp images were rated equal to 120 s/bp images. Coefficient of variance values for 120 s/bp and 90 s/bp images was significantly < 15%. The estimated annual savings to the hospital when reducing scan time was 8000-16,000 €/scanner.

CONCLUSION

Acquisition time can be reduced to 90 s/bp in response assessment FDG-PET/CT without compromising Deauville score or image quality. Reducing acquisition time can reduce costs to the clinic.

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.

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 ΔSUV_max 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 ΔSUV_max scale, which is based on SUV_max 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; ΔSUV_max > 66% vs. ≤ 66%), the positive predictive value was significantly lower with Deauville than ΔSUV_max (38.4% vs. 56.6%; P = 0.03). qPET and ΔSUV_max were strongly correlated on the log scale (Pearson r = 0.75). When plotted along corresponding percentiles, the positive predictive value curves for qPET and ΔSUV_max were superimposable, with low values up to the 85th percentile and a steep rise thereafter. The recommended threshold of 66% SUV_max 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 ΔSUV_max essentially carry the same information. The proportion of poor-risk patients identified is less than 15%.

Update on Quantitative Imaging for Predicting and Assessing Response in Oncology

Molecular imaging has revolutionized clinical oncology by imaging-specific facets of cancer biology. Through noninvasive measurements of tumor physiology, targeted radiotracers can serve as biomarkers for disease characterization, prognosis, response assessment, and predicting long-term response/survival. In turn, these imaging biomarkers can be utilized to tailor therapeutic regimens to tumor biology. In this article, we review biomarker applications for response assessment and predicting long-term outcomes. ¹⁸F-fluorodeoxyglucose (FDG), a measure of cellular glucose metabolism, is discussed in the context of lymphoma and breast and lung cancer. FDG has gained widespread clinical acceptance and has been integrated into the routine clinical care of several malignancies, most notably lymphoma. The novel radiotracers 16α-¹⁸F-fluoro-17β-estradiol and ¹⁸F-fluorothymidine are reviewed in application to the early prediction of response assessment of breast cancer. Through illustrative examples, we explore current and future applications of molecular imaging biomarkers in the advancement of precision medicine.

Fully automatic segmentation of diffuse large B cell lymphoma lesions on 3D FDG-PET/CT for total metabolic tumour volume prediction using a convolutional neural network

PURPOSE

Lymphoma lesion detection and segmentation on whole-body FDG-PET/CT are a challenging task because of the diversity of involved nodes, organs or physiological uptakes. We sought to investigate the performances of a three-dimensional (3D) convolutional neural network (CNN) to automatically segment total metabolic tumour volume (TMTV) in large datasets of patients with diffuse large B cell lymphoma (DLBCL).

METHODS

The dataset contained pre-therapy FDG-PET/CT from 733 DLBCL patients of 2 prospective LYmphoma Study Association (LYSA) trials. The first cohort (n = 639) was used for training using a 5-fold cross validation scheme. The second cohort (n = 94) was used for external validation of TMTV predictions. Ground truth masks were manually obtained after a 41% SUVmax adaptive thresholding of lymphoma lesions. A 3D U-net architecture with 2 input channels for PET and CT was trained on patches randomly sampled within PET/CTs with a summed cross entropy and Dice similarity coefficient (DSC) loss. Segmentation performance was assessed by the DSC and Jaccard coefficients. Finally, TMTV predictions were validated on the second independent cohort.

RESULTS

Mean DSC and Jaccard coefficients (± standard deviation) in the validations set were 0.73 ± 0.20 and 0.68 ± 0.21, respectively. An underestimation of mean TMTV by - 12 mL (2.8%) ± 263 was found in the validation sets of the first cohort (P = 0.27). In the second cohort, an underestimation of mean TMTV by - 116 mL (20.8%) ± 425 was statistically significant (P = 0.01).

CONCLUSION

Our CNN is a promising tool for automatic detection and segmentation of lymphoma lesions, despite slight underestimation of TMTV. The fully automatic and open-source features of this CNN will allow to increase both dissemination in routine practice and reproducibility of TMTV assessment in lymphoma patients.

Prognostic models integrating quantitative parameters from baseline and interim positron emission computed tomography in patients with diffuse large B-cell lymphoma: post-hoc analysis from the SAKK38/07 clinical trial

Positron emission computed tomography (PET/CT) in patients with diffuse large B-cell lymphoma (DLBCL) enrolled in a prospective clinical trial were reviewed to test the impact of quantitative parameters from interim PET/CT scans on overall (OS) and progression-free (PFS) survival. We centrally reviewed baseline and interim PET/CT scans of 138 patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone given every 14 days (R-CHOP14) in the SAKK38/07 trial (ClinicalTrial.gov identifier: NCT00544219). Cutoff values for maximum standardized uptake value (SUV_max ), metabolic tumor volume (MTV), total lesion glycolysis (TLG) and metabolic heterogeneity (MH) were defined by receiver operating characteristic analysis. Responses were scored using the Deauville scale (DS). Patients with DS 5 at interim PET/CT (defined by uptake >2 times higher than in normal liver) had worse PFS (P = 0.014) and OS (P < 0.0001). A SUV_max reduction (Δ) greater than 66% was associated with longer PFS (P = 0.0027) and OS (P < 0.0001). Elevated SUV_max , MTV, TLG, and MH at interim PET/CT also identified patients with poorer outcome. At multivariable analysis, ΔSUV_max and baseline MTV appeared independent outcome predictors. A prognostic model integrating ΔSUV_max and baseline MTV discriminated three risk groups with significantly (log-rank test for trend, P < 0.0001) different PFS and OS. Moreover, the integration of MH and clinical prognostic indices could further refine the prediction of OS. PET metrics-derived prognostic models perform better than the international indices alone. Integration of baseline and interim PET metrics identified poor-risk DLBCL patients who might benefit from alternative treatments.

Avadomide plus obinutuzumab in patients with relapsed or refractory B-cell non-Hodgkin lymphoma (CC-122-NHL-001): a multicentre, dose escalation and expansion phase 1 study

BACKGROUND

Avadomide (CC-122) is a novel oral cereblon-modulating agent with promising activity in non-Hodgkin lymphoma. We aimed to examine the safety and preliminary activity of avadomide plus obinutuzumab in patients with relapsed or refractory non-Hodgkin lymphoma.

METHODS

CC-122-NHL-001 was a phase 1b dose escalation and expansion study at eight sites in France, Italy, and the Netherlands. Eligible patients (aged ≥18 years) had histologically confirmed CD20-positive relapsed or refractory non-Hodgkin lymphoma, had an Eastern Cooperative Oncology Group performance status of 0 or 1, and had received previous treatment. In the dose expansion phase, only patients with previously treated relapsed or refractory follicular lymphoma (grade 1, 2, or 3a) were included. Avadomide was administered in escalating doses and two formulations: active pharmaceutical ingredient in capsule in 1·0 mg, 2·0 mg, 3·0 mg, and 4·0 mg doses and as formulated capsules in 3·0 mg and 4·0 mg doses orally once daily on days 1-5 followed by 2 days off (5-7-day schedule) every week of each 28-day cycle. Obinutuzumab 1000 mg was administered intravenously on days 2, 8, and 15 of cycle 1 and day 1 of cycles 2-8. Primary objectives were to determine the safety and tolerability, the non-tolerated dose, maximum tolerated dose, and recommended phase 2 dose (RP2D). All patients who received treatment were included in the safety analyses. Efficacy-evaluable patients completed at least one cycle of treatment and had baseline and at least one post-baseline assessment. The study is registered with ClinicalTrials.gov, NCT02417285 and EudraCT 2014-003333-26, and is ongoing.

FINDINGS

Between June 24, 2015, and Dec 5, 2018, 73 patients were enrolled and treated; 19 had diffuse large B-cell lymphoma, 53 follicular lymphoma, and one marginal zone lymphoma. Median follow-up was 253 days (IQR 127-448). The median number of previous anticancer regimens was three (IQR 2-4). The maximum tolerated dose and non-tolerated dose were not reached in the dose escalation phase. On the basis of safety and pharmacokinetic-pharmacodynamic data, the avadomide RP2D was established as 3·0 mg as formulated capsules on a 5-7-day schedule in combination with 1000 mg of obinutuzumab. Patients enrolled in the expansion cohort received the established RP2D of avadomide. Across all doses, three patients had dose-limiting toxicities; one patient treated at the RP2D had dose-limiting toxicity (grade 3 sepsis). The most common adverse events of grade 3 and above were neutropenia (41 [56%] of 73) and thrombocytopenia (17 [23%] of 73). 34 (47%) patients had serious adverse events, which were considered to be avadomide-related in 23 (32%) of 73 patients and obinutuzumab-related in 20 (27%) of 73 patients. Two treatment-related deaths occurred, one owing to tumour flare and one from acute myeloid leukaemia after study discontinuation.

INTERPRETATION

Avadomide plus obinutuzumab has a manageable toxicity, being a tolerable treatment option for most patients. Although the prespecified threshold for activity was not met in the trial, we believe that the preliminary antitumour activity of cereblon modulators plus next-generation anti-CD20 antibodies in heavily pretreated relapsed or refractory non-Hodgkin lymphoma warrants further investigation as a chemotherapy-free option in this setting.

FUNDING

Celgene Corporation.