Tumor Burden Measured by 18F-FDG PET/CT in Predicting Efficacy and Adverse Effects of Chimeric Antigen Receptor T-Cell Therapy in Non-Hodgkin Lymphoma

The predictive power of baseline metabolic and volumetric [18F]FDG PET parameters with different thresholds for early therapy failure and mortality risk in DLBCL patients undergoing CAR-T-cell therapy

Objective

[18F]FDG imaging is an integral part of patient management in CAR-T-cell therapy for recurrent or therapy-refractory DLBCL. The calculation methods of predictive power of specific imaging parameters still remains elusive. With this retrospective study, we sought to evaluate the predictive power of the baseline metabolic parameters and tumor burden calculated with automated segmentation via different thresholding methods for early therapy failure and mortality risk in DLBCL patients.

Materials and methods

Eighteen adult patients were enrolled, who underwent CAR-T-cell therapy accompanied by at least one pretherapeutic and two posttherapeutic [18F]FDG PET scans within 30 and 90 days between December 2018 and October 2023. We performed single-click automatic segmentation within VOIs in addition to extracting the SUV parameters to calculate the MTVs and TLGs by applying thresholds based on the concepts of a fixed absolute threshold with an SUVmax > 4.0, a relative absolute threshold with an isocontour of > 40 % of the SUVmax, a background threshold involving the addition of the liver SUV value and its 2 SD values, and only the liver SUV value.

Results

For early therapy failure, baseline metabolic parameters such as the SUVmax, SUVpeak and SUVmean tended to have greater predictive power than did the baseline metabolic burden. However, the baseline metabolic burden was superior in the prediction of mortality risk regardless of the thresholding method used.

Conclusion

This study revealed that automated delineation methods of metabolic tumor burden using different thresholds do not differ in outcome substantially. Therefore, the current clinical standard with a fixed absolute threshold value of SUV > 4.0 seems to be a feasible option.

Pre-infusion 18 F-FDG PET/CT for Prognostic and Toxicity Prediction in B-cell Non-Hodgkin Lymphoma Patients Undergoing Chimeric Antigen Receptor T-cell Therapy

PURPOSE

The aim of this study was to evaluate the value of 18 F-FDG PET/CT in predicting outcomes and toxicity for patients with B-cell non-Hodgkin lymphoma (B-NHL) who underwent chimeric antigen receptor T (CAR-T) cell therapy.

METHODS

This retrospective study included B-NHL patients who underwent CAR-T therapy and had pre-infusion 18 F-FDG PET/CT images. We recorded SUVmax, metabolic tumor volume (MTV), total lesion glycolysis (TLG), and various clinical and laboratory indexes. The primary endpoints were progression-free survival (PFS) and overall survival (OS). PFS and OS were estimated using the Kaplan-Meier method. In addition, we reported the correlation between PET/CT parameters and the objective response (OR), as well as cytokine release syndrome (CRS).

RESULTS

A total of 133 patients were enrolled in this study. The median follow-up duration was 20.8 months. SUVmax (with a cutoff value of 15.65) emerged as an independent metabolic parameter associated with PFS, OS, and OR. Patients with SUVmax ≥15.65 had a median PFS of 9.13 months (95% CI: 0.11-18.16), while the PFS for those with SUVmax<15.65 was not reached ( P =0.006). Furthermore, patients with SUVmax ≥15.65 exhibited significantly shorter average OS compared with those with SUVmax<15.65 (26.89 mo vs. 45.14 mo, P =0.010). In addition, the odds ratio for achieving an OR in patients with SUVmax ≥15.65 was found to be lower at 0.173 (95% CI: 0.056-0.539). Other factors associated with PFS included ECOG-PS, B symptoms, bulky mass, and extranodal sites, whereas IPI and LDH were associated with OS. Furthermore, SUVmax and Deauville scores showed a weak positive correlation with the occurrence of CRS.

CONCLUSIONS

The pretreatment PET/CT parameter SUVmax appears to be a promising predictive factor for efficacy and prognosis, as well as being associated with the occurrence of CRS. Consequently, we can conclude that this metabolic parameter from pretreatment PET/CT scans may serve as a valuable tool in guiding patient selection for CAR-T therapy and predicting potential side effects.

Mathematical modeling unveils the timeline of CAR-T cell therapy and macrophage-mediated cytokine release syndrome

Chimeric antigen receptor (CAR)-T cell therapy holds significant potential for cancer treatment, although disease relapse and cytokine release syndrome (CRS) remain as frequent clinical challenges. To better understand the mechanisms underlying the temporal dynamics of CAR-T cell therapy response and CRS, we developed a novel multi-layer mathematical model incorporating antigen-mediated CAR-T cell expansion, antigen-negative resistance, and macrophage-associated cytokine release. Three key mechanisms of macrophage activation are considered: release of damage-associated molecular patterns, antigen-binding mediated activation, and CD40-CD40L contact. The model accurately describes 25 patient time courses with different responses and IL-6 cytokine kinetics. We successfully link the dynamic shape of the response to interpretable model parameters and investigate the influence of CAR-T cell dose and initial tumor burden on the occurrence of cytokine release and treatment outcome. By disentangling the timeline of macrophage activation, the model identified distinct contributions of each activation mechanism, suggesting the CD40-CD40L axis as a major driver of cytokine release and a clinically feasible target to control the activation process and modulate cytokine peak height. Our multi-layer model provides a comprehensive framework for understanding the complex interactions between CAR-T cells, tumor cells, and macrophages during therapy.

18F-fluorodeoxyglucose positron emission tomography-compute tomography parameters for predicting the prognosis and toxicity in children and young adults with large B-cell lymphoma receiving chimeric antigen receptor T-cell therapy

Background

Chimeric antigen receptor (CAR) T-cell therapy has been proven to be an effective choice for patients with relapsed or refractory large B-cell lymphoma (LBCL). Early identification of patients who may have a poor prognosis and develop severe side effects is necessary. In this study, we aimed to assess the value of 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) parameters in predicting the prognosis and toxicity of CAR T therapy for children and young adults with LBCL.

Methods

This retrospective cohort study included patients with LBCL under 30 years of age who underwent 18F-FDG PET/CT at Beijing Friendship Hospital of Capital Medical University and Beijing GoBroad Boren Hospital before CAR T-cell infusion within 1 month. 18F-FDG PET/CT metabolic parameters including maximum standardized uptake value (SUVmax), total metabolic tumor volume (TMTV), and total lesion glycolysis (TLG) were recorded. Clinical characteristics and laboratory indicators were also collected. The main endpoints were progression-free survival (PFS) and overall survival (OS) as estimated by the Kaplan-Meier method and log-rank test. We also assessed the relationship between these metabolic and clinical parameters and severe toxicities, including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS).

Results

Forty-five patients were recruited. The median duration of the follow-up period was 13.9 months. Patients with an age-adjusted international prognostic index (aaIPI) 2-3 (P=0.014) and TMTV >101.4 mL (P=0.026) had a shorter PFS. Patients with Eastern Cooperative Oncology Group (ECOG) performance status 2-3 (P=0.015) and TMTV >101.4 mL (P=0.011) had a shorter OS. Lactate dehydrogenase (LDH) > upper normal limit (UNL) (P=0.030) and TMTV >101.4 mL (P=0.042) were associated with grade 2-4 CRS, and C-reactive protein (CRP) > UNL (P=0.014) was associated with grade 2-4 ICANS.

Conclusions

aaIPI and TMTV were independent risk factors for PFS, and ECOG score and TMTV had independent prognostic value for OS. Higher LDH and TMTV were associated with grade 2-4 CRS, and higher CRP was associated with more severe ICANS. Thus, integrating these metabolic parameters of 18F-FDG PET/CT and clinical-laboratory indicators can be valuable for managing children and young adults with B-cell lymphoma who have received CAR T-cell therapy.

Metabolic Tumor Volume Response after Bridging Therapy Determines Chimeric Antigen Receptor T-Cell Outcomes in Large B-Cell Lymphoma

PURPOSE

Greater disease burden is a well-established predictor of poorer outcomes following chimeric antigen receptor T-cell (CAR T) therapy. Although bridging therapy (BT) is widely used between leukapheresis and CAR T infusion, limited data have evaluated the impact of BT on CAR T outcomes. In this study, we hypothesized that the quantitative dynamics of radiomic cytoreduction during bridging are prognostic.

EXPERIMENTAL DESIGN

Patients with large B-cell lymphoma treated with CD19-CAR T from 2016 to 2022 were included in the study. Metabolic tumor volume (MTV) was determined for all patients on pre-leukapheresis PET and on post-BT/pre-infusion PET in those who received BT. Patients were stratified into "High" and "Low" disease burden using an MTV cutpoint of 65.4cc established by maximally selected log-rank statistic for progression-free survival (PFS).

RESULTS

Of 191 patients treated with CAR T, 144 (75%) received BT. In the BT cohort, 56% had a reduction in MTV post-BT. On multivariate analysis, the MTV trajectory across the bridging period remained significantly associated with PFS (P < 0.001); however, notably, patients with improved MTV (High->Low) had equivalent PFS compared with those with initially and persistently low MTV (Low->Low; HR for High->Low MTV: 2.74; 95% confidence interval, 0.82-9.18). There was a reduction in any grade immune effector cell-associated neurotoxicity syndrome in the High->Low MTV cohort as compared with the High->High MTV cohort (13% vs. 41%; P = 0.05).

CONCLUSIONS

This is the first study to use radiomics to quantify disease burden pre- and post-BT in a large real-world large B-cell lymphoma cohort. We demonstrate that effective BT can enable initially high-disease burden patients to achieve post-CAR T outcomes comparable with low-disease burden patients.

Prognostic significance of fludeoxyglucose positron emission tomography delta radiomics following bridging therapy in patients with large B-cell lymphoma undergoing CAR T-cell therapy

Purpose/objectives

Bridging radiation therapy (bRT) is increasingly being utilized prior to chimeric antigen receptor (CAR) T-cell therapy for large B-cell lymphoma (LBCL). It is unknown how the extent of cytoreduction during bRT impacts outcomes.

Materials/methods

We retrospectively reviewed patients with LBCL treated with bRT followed by CAR T-cell therapy. Metabolic tumor volume (MTV), maximum standardized uptake value (SUVmax), SUVmean, and total lesion glycolysis (TLG) were extracted from F18-fluorodeoxyglucose positron emission tomography (PET) scans acquired prior to bRT and between completion of bRT and CAR T-cell infusion. Delta radiomics based on changes of these values were then calculated. The association between delta radiomics and oncologic outcomes [progression-free survival (PFS), freedom from distant progression (FFDP), and local control (LC)] were then examined.

Results

Thirty-three sites across 23 patients with LBCL were irradiated. All metabolically active disease was treated in 10 patients. Following bRT, median overall decreases (including unirradiated sites) in MTV, SUVmax, SUVmean, and TLG were 22.2 cc (63.1%), 8.9 (36.8%), 3.4 (31.1%), and 297.9 cc (75.8%), respectively. Median decreases in MTV, SUVmax, SUVmean, and TLG in irradiated sites were 15.6 cc (91.1%), 17.0 (74.6%), 6.8 (55.3%), and 157.0 cc (94.6%), respectively. Median follow-up was 15.2 months. A decrease in SUVmax of at least 54% was associated with improved PFS (24-month PFS: 83.3% vs. 28.1%; p = 0.037) and FFDP (24-month FFDP: 100% vs. 62.4%; p < 0.001). A decrease in MTV of at least 90% was associated with improved FFDP (24-month FFDP: 100% vs. 62.4%; p < 0.001). LC was improved in sites with decreases in SUVmax of at least 71% (24-month LC: 100% vs. 72.7%; p < 0.001). Decreases of MTV by at least 90% (100% vs. 53.3%; p = 0.038) and TLG by at least 95% (100% vs. 56.3%; p = 0.067) were associated with an improved complete response rate.

Conclusion

bRT led to substantial reductions in MTV, SUVmax, SUVmean, and TLG. The relative extent of these decreases correlated with improved outcomes after CAR T-cell infusion. Prospective cohorts should validate the value of interim PET following bRT for quantifying changes in disease burden and associated prognosis.

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.

Influencing factors and solution strategies of chimeric antigen receptor T-cell therapy (CAR-T) cell immunotherapy

Chimeric antigen receptor T-cesll therapy (CAR-T) has achieved groundbreaking advancements in clinical application, ushering in a new era for innovative cancer treatment. However, the challenges associated with implementing this novel targeted cell therapy are increasingly significant. Particularly in the clinical management of solid tumors, obstacles such as the immunosuppressive effects of the tumor microenvironment, limited local tumor infiltration capability of CAR-T cells, heterogeneity of tumor targeting antigens, uncertainties surrounding CAR-T quality, control, and clinical adverse reactions have contributed to increased drug resistance and decreased compliance in tumor therapy. These factors have significantly impeded the widespread adoption and utilization of this therapeutic approach. In this paper, we comprehensively analyze recent preclinical and clinical reports on CAR-T therapy while summarizing crucial factors influencing its efficacy. Furthermore, we aim to identify existing solution strategies and explore their current research status. Through this review article, our objective is to broaden perspectives for further exploration into CAR-T therapy strategies and their clinical applications.

Biomarkers of outcome in patients undergoing CD19 CAR-T therapy for large B cell lymphoma

CD19-directed autologous chimeric antigen receptor T cell (CAR-T) therapy has transformed the management of relapsed/refractory (R/R) large B cell lymphoma (LBCL). Initially approved in the third line and beyond setting, CAR-T is now standard of care (SOC) for second-line treatment in patients with refractory disease or early relapse (progression within 12 months) following primary chemoimmunotherapy. Despite becoming SOC, most patients do not achieve complete response, and long-term cure is only observed in approximately 40% of patients. Accordingly, there is an urgent need to better understand the mechanisms of treatment failure and to identify patients that are unlikely to benefit from SOC CAR-T. The field needs robust biomarkers to predict treatment outcome, as better understanding of prognostic factors and mechanisms of resistance can inform on the design of novel treatment approaches for patients predicted to respond poorly to SOC CAR-T. This review aims to provide a comprehensive overview of clinical, molecular, imaging, and cellular features that have been shown to influence outcomes of CAR-T therapy in patients with R/R LBCL.

[18F]FDG PET/CT for prognosis and toxicity prediction of diffuse large B-cell lymphoma patients with chimeric antigen receptor T-cell therapy

PURPOSE

Chimeric antigen receptor (CAR) T-cell therapy has been confirmed to benefit patients with relapsed and/or refractory diffuse large B-cell lymphoma (DLBCL). It is important to provide precise and timely predictions of the efficacy and toxicity of CAR T-cell therapy. In this study, we evaluated the value of [18F]fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG PET/CT) combining with clinical indices and laboratory indicators in predicting outcomes and toxicity of anti-CD19 CAR T-cell therapy for DLBCL patients.

METHODS

Thirty-eight DLBCL patients who received CAR T-cell therapy and underwent [18F]FDG PET/CT within 3 months before (pre-infusion) and 1 month after CAR T-cell infusion (M1) were retrospectively reviewed and regularly followed up. Maximum standardized uptake value (SUVmax), total lesion glycolysis (TLG), metabolic tumor volume (MTV), clinical indices, and laboratory indicators were recorded at pre-infusion and M1 time points, and changes in these indices were calculated. Progression-free survival (PFS) and overall survival (OS) were as endpoints. Based on the multivariate Cox regression analysis, two predictive models for PFS and OS were developed and evaluated the efficiency. Pre-infusion indices were subjected to predict the grade of cytokine release syndrome (CRS) resulting from toxic reactions.

RESULTS

For survival analysis at a median follow-up time of 18.2 months, patients with values of international prognostic index (IPI), SUVmax at M1, and TLG at M1 above their optimal thresholds had a shorter PFS (median PFS: 8.1 months [IPI ≥ 2] vs. 26.2 months [IPI < 2], P = 0.025; 3.1 months [SUVmax ≥ 5.69] vs. 26.8 months [SUVmax < 5.69], P < 0.001; and 3.1 months [TLG ≥ 23.79] vs. 26.8 months [TLG < 23.79], P < 0.001). In addition, patients with values of SUVmax at M1 and ∆SUVmax% above their optimal thresholds had a shorter OS (median OS: 12.6 months [SUVmax ≥ 15.93] vs. 'not reached' [SUVmax < 15.93], P < 0.001; 32.5 months [∆SUVmax% ≥ -46.76] vs. 'not reached' [∆SUVmax% < -46.76], P = 0.012). Two novel predictive models for PFS and OS were visualized using nomogram. The calibration analysis and the decision curves demonstrated good performance of the models. Spearman's rank correlation (rs) analysis revealed that the CRS grade correlated strongly with the pre-infusion SUVmax (rs = 0.806, P < 0.001) and moderately with the pre-infusion TLG (rs = 0.534, P < 0.001). Multinomial logistic regression analysis revealed that the pre-infusion value of SUVmax correlated with the risk of developing a higher grade of CRS (P < 0.001).

CONCLUSION

In this group of DLBCL patients who underwent CAR T-cell therapy, SUVmax at M1, TLG at M1, and IPI were independent risk factors for PFS, and SUVmax at M1 and ∆SUVmax% for OS. Based on these indicators, two novel predictive models were established and verified the efficiency for evaluating PFS and OS. Moreover, pre-infusion SUVmax correlated with the severity of any subsequent CRS. We conclude that metabolic parameters measured using [18F]FDG PET/CT can identify DLBCL patients who will benefit most from CAR T-cell therapy, and the value before CAR T-cell infusion may predict its toxicity in advance.

Axicabtagene ciloleucel vs standard of care in second-line large B-cell lymphoma: outcomes by metabolic tumor volume

ABSTRACT

Metabolic tumor volume (MTV) assessed using 2-deoxy-2-[18F]fluoro-d-glucose positron emission tomography, a measure of tumor burden, is a promising prognostic indicator in large B-cell lymphoma (LBCL). This exploratory analysis evaluated relationships between baseline MTV (categorized as low [median or less] vs high [greater than median]) and clinical outcomes in the phase 3 ZUMA-7 study (NCT03391466). Patients with LBCL relapsed within 12 months of or refractory to first-line chemoimmunotherapy were randomized 1:1 to axicabtagene ciloleucel (axi-cel; autologous anti-CD19 chimeric antigen receptor T-cell therapy) or standard care (2-3 cycles of chemoimmunotherapy followed by high-dose chemotherapy with autologous stem cell transplantation in patients who had a response). All P values are descriptive. Within high- and low-MTV subgroups, event-free survival (EFS) and progression-free survival (PFS) were superior with axi-cel vs standard care. EFS in patients with high MTV (vs low MTV) was numerically shorter with axi-cel and was significantly shorter with standard care. PFS was shorter in patients with high MTV vs low MTV in both the axi-cel and standard-care arms, and median MTV was lower in patients in ongoing response at data cutoff vs others. Median MTV was higher in patients treated with axi-cel who experienced grade ≥3 neurologic events or cytokine release syndrome (CRS) than in patients with grade 1/2 or no neurologic events or CRS, respectively. Baseline MTV less than or equal to median was associated with better clinical outcomes in patients receiving axi-cel or standard care for second-line LBCL. The trial was registered at www.clinicaltrials.gov as #NCT03391466.

The Role of [18F]FDG PET/CT in Predicting Toxicity in Patients with NHL Treated with CAR-T: A Systematic Review

CAR-T-cell therapy, also referred to as chimeric antigen receptor T-cell therapy, is a novel method in the field of immunotherapy for the treatment of non-Hodgkin's lymphoma (NHL). In patients receiving CAR-T-cell therapy, fluorodeoxyglucose Positron Emission Tomography/Computer Tomography ([18F]FDG PET/CT) plays a critical role in tracking treatment response and evaluating the immunotherapy's overall efficacy. The aim of this study is to provide a systematic review of the literature on the studies aiming to assess and predict toxicity by means of [18F]FDG PET/CT in patients with NHL receiving CAR-T-cell therapy. PubMed/MEDLINE and Cochrane Central Register of Controlled Trials (CENTRAL) databases were interrogated by two investigators to seek studies involving the use of [18F]FDG PET/CT in patients with lymphoma undergoing CAR-T-cell therapy. The comprehensive computer literature search allowed 11 studies to be included. The risk of bias for the studies included in the systematic review was scored as low by using version 2 of the "Quality Assessment of Diagnostic Accuracy Studies" tool (QUADAS-2). The current literature emphasizes the role of [18F]FDG PET/CT in assessing and predicting toxicity in patients with NHL receiving CAR-T-cell therapy, highlighting the evolving nature of research in CAR-T-cell therapy. Additional studies are warranted to increase the collected evidence in the literature.

FDG-PET in Chimeric Antigen Receptor T-Cell (CAR T-Cell) Therapy Toxicity: A Systematic Review

The utilization of chimeric antigen receptor (CAR) T-cell therapy to target cluster of differentiation (CD)19 in cancer immunotherapy has been a recent and significant advancement. Although this approach is highly specific and selective, it is not without complications. Therefore, a systematic review was conducted to assess the current state of positron emission tomography (PET) in evaluating the adverse effects induced by CAR T-cell therapy. A thorough search of relevant articles was performed in databases such as PubMed, Scopus, and Web of Science up until March 2024. Two reviewers independently selected articles and extracted data, which was then organized and categorized using Microsoft Excel. The risk of bias and methodological quality was assessed. In total, 18 articles were examined, involving a total of 753 patients, in this study. A wide range of utilities were analyzed, including predictive, correlative, and diagnostic utilities. While positive outcomes were observed in all the mentioned areas, quantitative analysis of the included studies was hindered by their heterogeneity and use of varying PET-derived parameters. This study offers a pioneering exploration of this promising field, with the goal of encouraging further and more focused research in upcoming clinical trials.

Multicenter development of a PET-based risk assessment tool for product-specific outcome prediction in large B-cell lymphoma patients undergoing CAR T-cell therapy

PURPOSE

The emergence of chimeric antigen receptor (CAR) T-cell therapy fundamentally changed the management of individuals with relapsed and refractory large B-cell lymphoma (LBCL). However, real-world data have shown divergent outcomes for the approved products. The present study therefore set out to evaluate potential risk factors in a larger cohort.

METHODS

Our analysis set included 88 patients, treated in four German university hospitals and one Italian center, who had undergone 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (PET) before CAR T-cell therapy with tisagenlecleucel or axicabtagene ciloleucel. We first determined the predictive value of conventional risk factors, treatment lines, and response to bridging therapy for progression-free survival (PFS) through forward selection based on Cox regression. In a second step, the additive potential of two common PET parameters was assessed. Their optimal dichotomizing thresholds were calculated individually for each CAR T-cell product.

RESULTS

Extra-nodal involvement emerged as the most relevant of the conventional tumor and patient characteristics. Moreover, we found that inclusion of metabolic tumor volume (MTV) further improves outcome prediction. The hazard ratio for a PFS event was 1.68 per unit increase of our proposed risk score (95% confidence interval [1.20, 2.35], P = 0.003), which comprised both extra-nodal disease and lymphoma burden. While the most suitable MTV cut-off among patients receiving tisagenlecleucel was 11 mL, a markedly higher threshold of 259 mL showed optimal predictive performance in those undergoing axicabtagene ciloleucel treatment.

CONCLUSION

Our analysis demonstrates that the presence of more than one extra-nodal lesion and higher MTV in LBCL are associated with inferior outcome after CAR T-cell treatment. Based on an assessment tool including these two factors, patients can be assigned to one of three risk groups. Importantly, as shown by our study, metabolic tumor burden might facilitate CAR T-cell product selection and reflect the individual need for bridging therapy.

Biomarkers for prediction of CAR T therapy outcomes: current and future perspectives

Chimeric antigen receptor (CAR) T cell therapy holds enormous potential for the treatment of hematologic malignancies. Despite its benefits, it is still used as a second line of therapy, mainly because of its severe side effects and patient unresponsiveness. Numerous researchers worldwide have attempted to identify effective predictive biomarkers for early prediction of treatment outcomes and adverse effects in CAR T cell therapy, albeit so far only with limited success. This review provides a comprehensive overview of the current state of predictive biomarkers. Although existing predictive metrics correlate to some extent with treatment outcomes, they fail to encapsulate the complexity of the immune system dynamics. The aim of this review is to identify six major groups of predictive biomarkers and propose their use in developing improved and efficient prediction models. These groups include changes in mitochondrial dynamics, endothelial activation, central nervous system impairment, immune system markers, extracellular vesicles, and the inhibitory tumor microenvironment. A comprehensive understanding of the multiple factors that influence therapeutic efficacy has the potential to significantly improve the course of CAR T cell therapy and patient care, thereby making this advanced immunotherapy more appealing and the course of therapy more convenient and favorable for patients.

Reducing and controlling metabolic active tumor volume prior to CAR T-cell infusion can improve survival outcomes in patients with large B-cell lymphoma

Bridging therapy before CD19-directed chimeric antigen receptor (CAR) T-cell infusion is frequently applied in patients with relapsed or refractory Large B-cell lymphoma (r/r LBCL). This study aimed to assess the influence of quantified MATV and MATV-dynamics, between pre-apheresis (baseline) and pre-lymphodepleting chemotherapy (pre-LD) MATV, on CAR T-cell outcomes and toxicities in patients with r/r LBCL. MATVs were calculated semi-automatically at baseline (n = 74) and pre-LD (n = 68) in patients with r/r LBCL who received axicabtagene ciloleucel. At baseline, patients with a low MATV (< 190 cc) had a better time to progression (TTP) and overall survival (OS) compared to high MATV patients (p < 0.001). High MATV patients who remained stable or reduced upon bridging therapy showed a significant improvement in TTP (p = 0.041) and OS (p = 0.015), compared to patients with a high pre-LD MATV (> 480 cc). Furthermore, high MATV baseline was associated with severe cytokine release syndrome (CRS, p = 0.001). In conclusion, patients with low baseline MATV had the best TTP/OS and effective reduction or controlling MATV during bridging improved survival outcomes in patients with a high baseline MATV, providing rationale for the use of more aggressive bridging regimens.

Role of FDG PET/CT in Patients With Lymphoma Treated With Chimeric Antigen Receptor T-Cell Therapy: Current Concepts

Chimeric antigen receptor (CAR) T-cell therapy is a cellular therapy in which the patient's T cells are enhanced to recognize and bind to specific tumor antigens. CAR T-cell therapy was initially developed for the treatment of leukemia, but its current main indication is the treatment of relapsed or refractory non-Hodgkin lymphoma. FDG PET/CT plays a fundamental role in the diagnosis, staging, therapy response assessment, and recurrence evaluation of patients with metabolically active lymphoma. Consistent with the examination's role in lymphoma management, FDG PET/CT is also the imaging modality of choice to evaluate patients before and after CAR T-cell therapy, and evidence supporting its utility in this setting continues to accumulate. In this article, we review current concepts in CAR T-cell therapy in patients with lymphoma, emphasizing the critical role of FDG PET/CT before and after therapy. A framework is presented that entails performing FDG PET/CT at four time points over the course of CAR T-cell therapy: pretherapy at baseline at the time of decision to administer CAR T-cell therapy and after any bridging therapies and posttherapy 1 and 3 months after infusion. PET parameters assessed at these time points predict various patient outcomes.

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.

Three-year follow-up analysis of axicabtagene ciloleucel in relapsed/refractory indolent non-Hodgkin lymphoma (ZUMA-5)

ABSTRACT

Axicabtagene ciloleucel (axi-cel) is an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy approved for relapsed/refractory (R/R) follicular lymphoma (FL). Approval was supported by the phase 2, multicenter, single-arm ZUMA-5 study of axi-cel for patients with R/R indolent non-Hodgkin lymphoma (iNHL; N = 104), including FL and marginal zone lymphoma (MZL). In the primary analysis (median follow-up, 17.5 months), the overall response rate (ORR) was 92% (complete response rate, 74%). Here, we report long-term outcomes from ZUMA-5. Eligible patients with R/R iNHL after ≥2 lines of therapy underwent leukapheresis, followed by lymphodepleting chemotherapy and axi-cel infusion (2 × 106 CAR T cells per kg). The primary end point was ORR, assessed in this analysis by investigators in all enrolled patients (intent-to-treat). After median follow-up of 41.7 months in FL (n = 127) and 31.8 months in MZL (n = 31), ORR was comparable with that of the primary analysis (FL, 94%; MZL, 77%). Median progression-free survival was 40.2 months in FL and not reached in MZL. Medians of overall survival were not reached in either disease type. Grade ≥3 adverse events of interest that occurred after the prior analyses were largely in recently treated patients. Clinical and pharmacokinetic outcomes correlated negatively with recent exposure to bendamustine and high metabolic tumor volume. After 3 years of follow-up in ZUMA-5, axi-cel demonstrated continued durable responses, with very few relapses beyond 2 years, and manageable safety in patients with R/R iNHL. The ZUMA-5 study was registered at www.clinicaltrials.gov as #NCT03105336.

PET/CT in the Evaluation of CAR-T Cell Immunotherapy in Hematological Malignancies

Chimeric antigen receptor (CAR)-T cell-based immunotherapy has emerged as a path-breaking strategy for certain hematological malignancies. Assessment of the response to CAR-T therapy using quantitative imaging techniques such as positron emission tomography/computed tomography (PET/CT) has been broadly investigated. However, the definitive role of PET/CT in CAR-T therapy remains to be established. [18F]FDG PET/CT has demonstrated high sensitivity and specificity for differentiating patients with a partial and complete response after CAR-T therapy in lymphoma. The early therapeutic response and immune-related adverse effects such as cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome can also be detected on [18F]FDG PET images. In otherwise asymptomatic lymphoma patients with partial response following CAR-T therapy, the only positive findings could be abnormal PET/CT results. In multiple myeloma, a negative [18F]FDG PET/CT after receiving B-cell maturation antigen-directed CAR-T therapy has been associated with a favorable prognosis. In leukemia, [18F]FDG PET/CT can detect extramedullary metastases and treatment responses after therapy. Hence, PET/CT is a valuable imaging tool for patients undergoing CAR-T therapy for pretreatment evaluation, monitoring treatment response, assessing safety, and guiding therapeutic strategies. Developing guidelines with standardized cutoff values for various PET parameters and tumor cell-specific tracers may improve the efficacy and safety of CAR-T therapy.

Advancing the frontiers of adaptive cell therapy: A transformative mechanistic journey from preclinical to clinical settings

Although the concept of using the patient's immune system to combat cancer has been around for a while, it is only in recent times that substantial progress has been achieved in this field. Over the last ten years, there has been a significant advancement in the treatment of cancer through immune checkpoint blockade. This treatment has been approved for multiple types of tumors. Another approach to modifying the immune system to detect tumor cells and fight them off is adaptive cell therapy (ACT). This therapy involves using T cells that have been modified with either T cell receptors (TCR) or chimeric antigen receptors (CAR) to target the tumor cells. ACT has demonstrated encouraging outcomes in different types of tumors, and clinical trials are currently underway worldwide to enhance this form of treatment. This review focuses on the advancements that have been made in ACT from preclinical to clinical settings till now.

Population-Based External Validation of the EASIX Scores to Predict CAR T-Cell-Related Toxicities

Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) can hamper the clinical benefit of CAR T-cell therapy in patients with relapsed/refractory large B-cell lymphoma (r/r LBCL). To assess the risk of CRS and ICANS, the endothelial activation and stress index (EASIX), the modified EASIX (m-EASIX), simplified EASIX (s-EASIX), and EASIX with CRP/ferritin (EASIX-F(C)) were proposed. This study validates these scores in a consecutive population-based cohort. Patients with r/r LBCL treated with axicabtagene ciloleucel were included (n = 154). EASIX scores were calculated at baseline, before lymphodepletion (pre-LD) and at CAR T-cell infusion. The EASIX and the s-EASIX at pre-LD were significantly associated with ICANS grade ≥ 2 (both p = 0.04), and the EASIX approached statistical significance at infusion (p = 0.05). However, the predictive performance was moderate, with area under the curves of 0.61-0.62. Validation of the EASIX-FC revealed that patients in the intermediate risk group had an increased risk of ICANS grade ≥ 2 compared to low-risk patients. No significant associations between EASIX scores and CRS/ICANS grade ≥ 3 were found. The (m-/s-) EASIX can be used to assess the risk of ICANS grade ≥ 2 in patients treated with CAR T-cell therapy. However, due to the moderate performance of the scores, further optimization needs to be performed before broad implementation as a clinical tool, directing early intervention and guiding outpatient CAR T-cell treatment.

Clinical Application of 18F-FDG-PET Quantification in Hematological Malignancies: Emphasizing Multiple Myeloma, Lymphoma and Chronic Lymphocytic Leukemia

Most hematological malignancies display heightened glycolytic activity, leading to their detectability through 18F-FDG-PET imaging. PET quantification enables the extraction of metabolic information from tumors. Among various PET measurements, maximum standardized uptake value (SUVmax), which indicates the highest value of 18F-FDG uptake within the tumor, has emerged as the commonly used parameter in clinical oncology. This is because of SUVmax ease of calculation using most available commercial workstations, as well as its simplicity and independence from observer interpretation. Nonetheless, SUVmax represents the increase in activity within a specific small area, which may not fully capture the overall tumor uptake. Volumetric PET parameters have been identified as a potential solution to overcome certain limitations associated with SUVmax. However, these parameters are influenced by the low spatial resolution of PET when assessing small lesions. Another challenge is the high number of lesions observed in some patients, leading to a time-consuming process for evaluating all focal lesions. Some institutions recently have started advocating for CT-based segmentation as a method for measuring radiotracer uptake in the bone marrow and overall bone of the patients. This review article aims to provide insights into clinical application of PET quantification specifically focusing on 3 major hematologic malignancies: multiple myeloma, lymphoma, and chronic lymphocytic leukemia.

Brain FDG-PET findings in chimeric antigen receptor T-cell therapy neurotoxicity for diffuse large B-cell lymphoma

BACKGROUND AND PURPOSE

Chimeric antigen receptor (CAR) T-cell therapy is potentially associated with treatment-related toxicities mainly consisting of cytokine release syndrome (CRS) and immune-effector cell-associated neurotoxicity syndrome (ICANS). We evaluated brain metabolic correlates of CRS with and without ICANS in diffuse large B-cell lymphoma patients treated with CAR-T.

METHODS

Twenty-one refractory DLCBLs underwent whole-body and brain [18 F]-fluorodeoxyglucose (FDG) PET before and 30 days after treatment with CAR-T. Five patients did not develop inflammatory-related side effects, 11 patients developed CRS, while in 5 patients CRS evolved in ICANS. Baseline and post-CAR-T brain FDG-PET were compared with a local controls dataset to identify hypometabolic patterns both at single-patient and group levels (p < .05 after correction for family-wise error [FWE). Metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were computed on baseline FDG-PET and compared between patients' subgroups (t-test).

RESULTS

ICANS showed an extended and bilateral hypometabolic pattern mainly involving the orbitofrontal cortex, frontal dorsolateral cortex, and anterior cingulate (p < .003 FWE-corrected). CRS without ICANS showed significant hypometabolism in less extended clusters mainly involving bilateral medial and lateral temporal lobes, posterior parietal lobes, anterior cingulate, and cerebellum (p < .002 FWE-corrected). When compared, ICANS showed a more prominent hypometabolism in the orbitofrontal and frontal dorsolateral cortex in both hemispheres than CRS (p < .002 FWE-corrected). Mean baseline MTV and TLG were significantly higher in ICANS than CRS (p < .02).

CONCLUSIONS

Patients with ICANS are characterized by a frontolateral hypometabolic signature coherently with the hypothesis of ICANS as a predominant frontal syndrome and with the more prominent susceptibility of frontal lobes to cytokine-induced inflammation.

Neutralizing IFNγ improves safety without compromising efficacy of CAR-T cell therapy in B-cell malignancies

Chimeric antigen receptor T (CAR-T) cell therapy may achieve long-lasting remission in patients with B-cell malignancies not responding to conventional therapies. However, potentially severe and hard-to-manage side effects, including cytokine release syndrome (CRS), neurotoxicity and macrophage activation syndrome, and the lack of pathophysiological experimental models limit the applicability and development of this form of therapy. Here we present a comprehensive humanized mouse model, by which we show that IFNγ neutralization by the clinically approved monoclonal antibody, emapalumab, mitigates severe toxicity related to CAR-T cell therapy. We demonstrate that emapalumab reduces the pro-inflammatory environment in the model, thus allowing control of severe CRS and preventing brain damage, characterized by multifocal hemorrhages. Importantly, our in vitro and in vivo experiments show that IFNγ inhibition does not affect the ability of CD19-targeting CAR-T (CAR.CD19-T) cells to eradicate CD19+ lymphoma cells. Thus, our study provides evidence that anti-IFNγ treatment might reduce immune related adverse effect without compromising therapeutic success and provides rationale for an emapalumab-CAR.CD19-T cell combination therapy in humans.

PET/CT in Non-Hodgkin Lymphoma: An Update

Non-Hodgkin lymphomas represents a heterogeneous group of lymphoproliferative disorders characterized by different clinical courses, varying from indolent to highly aggressive. ¹⁸F-FDG-PET/CT is the current state-of-the-art diagnostic imaging, for the staging, restaging and evaluation of response to treatment in lymphomas with avidity for ¹⁸F-FDG, despite it is not routinely recommended for surveillance. PET-based response criteria (using five-point Deauville Score) are nowadays uniformly applied in FDG-avid lymphomas. In this review, a comprehensive overview of the role of ¹⁸F-FDG-PET in Non-Hodgkin lymphomas is provided, at each relevant point of patient management, particularly focusing on recent advances on diffuse large B-cell lymphoma and follicular lymphoma, with brief updates also on other histotypes (such as marginal zone, mantle cell, primary mediastinal- B cell lymphoma and T cell lymphoma). PET-derived semiquantitative factors useful for patient stratification and prognostication and emerging radiomics research are also presented.

Safety and efficacy of tisagenlecleucel in patients with relapsed or refractory B-cell lymphoma: the first real-world evidence in Japan

BACKGROUND

Tisagenlecleucel, an autologous CD19-directed T-cell immunotherapy, can induce a durable response in adult patients with relapsed/refractory (r/r) B-cell lymphoma.

METHODS

To elucidate the outcome of chimeric antigen receptor (CAR) T-cell therapy in Japanese, we retrospectively analyzed the outcomes of 89 patients who received tisagenlecleucel for r/r diffuse large B-cell lymphoma (n = 71) or transformed follicular lymphoma (n = 18).

RESULTS

With a median follow-up of 6.6-months, 65 (73.0%) patients achieved a clinical response. The overall survival (OS) and event-free survival (EFS) rates at 12 months were 67.0% and 46.3%, respectively. Overall, 80 patients (89.9%) had cytokine release syndrome (CRS), and 6 patients (6.7%) had a grade ≥ 3 event. ICANS occurred in 5 patients (5.6%); only 1 patient had grade 4 ICANS. Representative infectious events of any grade were cytomegalovirus viremia, bacteremia and sepsis. The most common other adverse events were ALT elevation, AST elevation, diarrhea, edema, and creatinine elevation. No treatment-related mortality was observed. A Sub-analysis showed that a high metabolic tumor volume (MTV; ≥ 80 ml) and stable disease /progressive disease before tisagenlecleucel infusion were both significantly associated with a poor EFS and OS in a multivariate analysis (P < 0.05). Notably, the combination of these 2 factors efficiently stratified the prognosis of these patients (HR 6.87 [95% CI 2.4-19.65; P < 0.05] into a high-risk group).

CONCLUSION

We report the first real-world data on tisagenlecleucel for r/r B-cell lymphoma in Japan. Tisagenlecleucel is feasible and effective, even in late line treatment. In addition, our results support a new algorithm for predicting the outcomes of tisagenlecleucel.

Bridging Radiation Rapidly and Effectively Cytoreduces High-Risk Relapsed/Refractory Aggressive B Cell Lymphomas Prior to Chimeric Antigen Receptor T Cell Therapy

Greater tumor burden before CD19-targeted chimeric antigen receptor T cell (CAR-T) therapy predicts lower complete response rate and shorter overall survival (OS) in patients with aggressive non-Hodgkin lymphoma (NHL). Recent patterns of failure studies have identified lesion characteristics, including size, standard uptake value (SUV), and extranodal location, as associated with post-CAR-T therapy failure. Here we analyzed the effect of bridging radiation-containing treatment (BRT) on pre-CAR-T therapy lesion- and patient-level characteristics and post-CAR-T therapy outcomes, including patterns of failure. Consecutive NHL patients who received radiation therapy from 30 days before leukapheresis until CAR T cell infusion were reviewed. Metabolic tumor volume (MTV) was contoured with a threshold SUV of 4. The first post-CAR-T therapy failures were categorized as preexisting/new/mixed with respect to pre-CAR-T therapy disease and in-field/marginal/distant with respect to BRT. Forty-one patients with diffuse large B cell lymphoma (DLBCL; n = 33), mantle cell lymphoma (n = 7), or Burkitt lymphoma (n = 1) were identified. BRT significantly improved established high-risk parameters of post-CAR-T therapy progression, including in-field median MTV (45.5 cc to .2 cc; P < .001), maximum SUV (18.1 to 4.4; P < .001), diameter (5.5 cm to 3.2 cm; P < .001), and lactate dehydrogenase (LDH; 312 to 232; P = .025). DLBCL patients with lower LDH levels post-BRT had improved progression-free survival (PFS; P = .001). In DLBCL, first failures were new in 7 of 19 patients, preexisting in 5 of 19, and mixed in 7 of 19; with respect to BRT, 4 of 19 were in-field and 4 of 19 were marginal. Post-CAR-T therapy survival was similar in patients with initially low MTV and those with newly low MTV post-BRT using a statistically determined threshold of 16 cc (PFS, 26 months versus 31 months; OS unreached for both). BRT produced significant cytoreductions in diameter, SUV, MTV, and LDH, all predictors of poor post-CAR-T therapy outcomes. Similar PFS and OS in patients with initially low MTV and those who achieved newly low MTV after BRT suggest that BRT may "convert" poor-risk patients to better risk. In the future, the response to BRT may allow for risk stratification and individualization of bridging strategies.

Early Hyperprogression of Lymphoma Detected by 18 F-FDG PET/CT After Chimeric Antigen Receptor T-Cell Therapy

ABSTRACT

18 F-FDG PET/CT plays important roles in the staging, treatment monitoring, and prognostic assessment of lymphoma. A 65-year-old woman with refractory large B-cell lymphoma underwent 18 F-FDG PET/CT imaging 35 days after a chimeric antigen receptor T-cell therapy. The images showed progression of the left maxillary lesion and additional involvement of the left facial subcutaneous tissue. Pathological examination of the left facial lesion led to a diagnosis of early hyperprogression of lymphoma.

Prognostic value of baseline and early response FDG-PET/CT in patients with refractory and relapsed aggressive B-cell lymphoma undergoing CAR-T cell therapy

PURPOSE

Chimeric antigen receptor (CAR)-T cells are a viable treatment option for patients with relapsed or refractory (r/r) aggressive B-cell lymphomas. The prognosis of patients who relapse after CAR-T cell treatment is dismal and factors predicting outcomes need to be identified. Our aim was to assess the value of FDG-PET/CT in terms of predicting patient outcomes.

METHODS

Twenty-two patients with r/r B-cell lymphoma who received CAR-T cell treatment with tisagenlecleucel (n = 17) or axicabtagene ciloleucel (n = 5) underwent quantitative FDG-PET/CT before (PET-0) and 1 month after infusion of CAR-T cells (PET-1). PET-1 was classified as complete metabolic response (CMR, Deauville score 1-3) or non-CMR (Deauville score 4-5).

RESULTS

At the time of PET-1, 12/22 (55%) patients showed CMR, ten (45%) patients non-CMR. 7/12 (58%) CMR patients relapsed after a median of 223 days, three of them (25%) died. 9/10 (90%) non-CMR patients developed relapse or progressive disease after a median of 91 days, eight of them (80%) died. CMR patients demonstrated a significantly lower median total metabolic tumor volume (TMTV) in PET-0 (1 ml) than non-CMR patients (225 ml).

CONCLUSION

Our results confirm the prognostic value of PET-1. 42% of all CMR patients are still in remission 1 year after CAR T-cell treatment. 90% of the non-CMR patients relapsed, indicating the need for early intervention. Higher TMTV before CAR-T cell infusion was associated with lower chances of CMR.

Outcome Prediction in Patients With Large B-cell Lymphoma Undergoing Chimeric Antigen Receptor T-cell Therapy

The introduction of chimeric antigen receptor (CAR) T-cell therapy has led to a fundamental shift in the management of relapsed and refractory large B-cell lymphoma. However, our understanding of risk factors associated with non-response is still insufficient and the search for predictive biomarkers continues. Some parameters measurable on ¹⁸F-fluorodeoxyglucose positron emission tomography (PET) may be of additional value in this context. A total of 47 individuals from three German university centers who underwent re-staging with PET prior to CAR T-cell therapy were enrolled into the present study. After multivariable analysis considering tumor characteristics and patient factors that might affect progression-free survival (PFS), we investigated whether metabolic tumor volume (MTV) or maximum standardized uptake value (SUV_max) further improve risk stratification. Their most suitable cut-offs were determined by Cox and logistic regression. Forward selection identified extra-nodal disease as the most predictive factor of those routinely available, and we found it to be associated with significantly inferior overall survival after CAR T-cell treatment (P = 0.012). Furthermore, patients with MTV and SUV_max higher than the optimal threshold of 11 mL and 16.7, respectively, experienced shorter PFS (P = 0.016 and 0.002, respectively). Hence, these risk factors might be useful for selection of individuals likely to benefit from CAR T-cell therapy and their management.

Whole body FDG PET/MR for progression free and overall survival prediction in patients with relapsed/refractory large B-cell lymphomas undergoing CAR T-cell therapy

BACKGROUND

To find semi-quantitative and quantitative Positron Emission Tomography/Magnetic Resonance (PET/MR) imaging metrics of both tumor and non-malignant lymphoid tissue (bone marrow and spleen) for Progression Free Survival (PFS) and Overall Survival (OS) prediction in patients with relapsed/refractory (r/r) large B-cell lymphoma (LBCL) undergoing Chimeric Antigen Receptor (CAR) T-cell therapy.

METHODS

A single-center prospective study of 16 r/r LBCL patients undergoing CD19-targeted CAR T-cell therapy. Whole body 18F-fluorodeoxyglucose (FDG) PET/MR imaging pre-therapy and 3 weeks post-therapy were followed by manual segmentation of tumors and lymphoid tissues. Semi-quantitative and quantitative metrics were extracted, and the metric-wise rate of change (Δ) between post-therapy and pre-therapy calculated. Tumor metrics included maximum Standardized Uptake Value (SUV_max), mean SUV (SUV_mean), Metabolic Tumor Volume (MTV), Tumor Lesion Glycolysis (TLG), structural volume (V), total structural tumor burden (V_total) and mean Apparent Diffusion Coefficient (ADC_mean). For lymphoid tissues, metrics extracted were SUV_mean, mean Fat Fraction (FF_mean) and ADC_mean for bone marrow, and SUV_mean, V and ADC_mean for spleen. Univariate Cox regression analysis tested the relationship between extracted metrics and PFS and OS. Survival curves were produced using Kaplan-Meier analysis and compared using the log-rank test, with the median used for dichotomization. Uncorrected p-values < 0.05 were considered statistically significant. Correction for multiple comparisons was performed, with a False Discovery Rate (FDR) < 0.05 considered statistically significant.

RESULTS

Pre-therapy (p < 0.05, FDR < 0.05) and Δ (p < 0.05, FDR > 0.05) total tumor burden structural and metabolic metrics were associated with PFS and/or OS. According to Kaplan-Meier analysis, a longer PFS was reached for patients with pre-therapy MTV ≤ 39.5 ml, ΔMTV≤1.35 and ΔTLG≤1.35. ΔSUV_max was associated with PFS (p < 0.05, FDR > 0.05), while ΔADC_mean was associated with both PFS and OS (p < 0.05, FDR > 0.05). ΔADC_mean > 0.92 gave longer PFS and OS in the Kaplan-Meier analysis. Pre-therapy bone marrow SUV_mean was associated with PFS (p < 0.05, FDR < 0.05) and OS (p < 0.05, FDR > 0.05). For bone marrow FDG uptake, patient stratification was possible pre-therapy (SUV_mean ≤ 1.8).

CONCLUSIONS

MTV, tumor ADC_mean and FDG uptake in bone marrow unaffected by tumor infiltration are possible PET/MR parameters for prediction of PFS and OS in r/r LBCL treated with CAR T-cells.

TRIAL REGISTRATION

EudraCT 2016-004043-36.

Overcoming resistance to anti-CD19 CAR T-cell therapy in B-cell malignancies

Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy has rapidly changed current treatment pattern, providing a better option for individuals with primary refractory or relapsed B-cell non-Hodgkin lymphoma (r/r B-NHL) and B-cell acute lymphoblastic leukemia (r/r B-ALL). However, despite the outstanding efficacy, a high relapse rate is still found in some B-cell malignancies after anti-CD19 CAR T-cell therapy, which emerges as a main barrier for improving the overall response and long-term outcomes. Understanding the resistance mechanism is crucial to improve current CAR T products, better incorporate them into the current therapy system and develop novel CAR approaches. Herein, we discuss the latest advances in understanding the mechanisms limiting efficacy of CAR T-cell therapy, resulting in CD19 negative (CD19^- ) and CD19 positive (CD19⁺ ) relapses. We also provide a whole scenario of current potential strategies to overcome these barriers.

The risk factors and early predictive model of hematotoxicity after CD19 chimeric antigen receptor T cell therapy

Hematotoxicity is the most common long-term adverse event after chimeric antigen receptor T cell (CAR-T) therapy. Here, a total of 71 patients with relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL) or large B-cell lymphoma (LBCL) were used to develop an early hematotoxicity predictive model and verify the accuracy of this model. The incidences of early hematotoxicity at 3 month following CAR-T infusion in B-ALL and LBCL were 45.5% and 38.5%, respectively. Multivariate analyses revealed that the severity of cytokine release syndrome (CRS) was an independent risk factor affecting early hematotoxicity. The analysis between the peak cytokine levels and early hematotoxicity suggested that tumor necrosis factor-α (TNF-α) and C-reactive protein (CRP) were closely associated with early hematotoxicity. Then, an early predictive model of hematotoxicity was constructed based on the peak contents of TNF-α and CRP. This model could diagnose early hematotoxicity with positive predictive values of 87.7% and 85.0% in training and validation cohorts, respectively. Lastly, we constructed the nomogram for clinical practice to predict the risk of early hematotoxicity, which performed well compared with the observed probability. This early predictive model is instrumental in the risk stratification of CAR-T recipients with hematotoxicity and early intervention for high-risk patients.

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.

CAR T-Cell Therapy Predictive Response Markers in Diffuse Large B-Cell Lymphoma and Therapeutic Options After CART19 Failure

Immunotherapy with T cells genetically modified with chimeric antigen receptors (CARs) has shown significant clinical efficacy in patients with relapsed/refractory B-cell lymphoma. Nevertheless, more than 50% of treated patients do not benefit from such therapy due to either absence of response or further relapse. Elucidation of clinical and biological features that would predict clinical response to CART19 therapy is of paramount importance and eventually may allow for selection of those patients with greater chances of response. In the last 5 years, significant clinical experience has been obtained in the treatment of diffuse large B-cell lymphoma (DLBCL) patients with CAR19 T cells, and major advances have been made on the understanding of CART19 efficacy mechanisms. In this review, we discuss clinical and tumor features associated with response to CART19 in DLBCL patients as well as the impact of biological features of the infusion CART19 product on the clinical response. Prognosis of DLBCL patients that fail CART19 is poor and therapeutic approaches with new drugs are also discussed.