Prognostic Value of 18F-FDG PET/CT in Diffuse Large B-Cell Lymphoma Treated with a Risk-Adapted Immunochemotherapy Regimen

2-deoxy-2-[18F]FDG PET Imaging for Therapy Assessment in Hodgkin's and Non-Hodgkin Lymphomas

The 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography combined with computed tomography (PET/CT) has contributed to outcome improvement of patients with lymphoma. The use of [18F]FDG PET/CT for staging and response assessment is successfully applied both in routine clinical practice and in clinical trials. The challenges lie in enhancing the outcomes of lymphoma patients, particularly those with advanced or refractory/relapsed disease, and to minimize the long-term toxicity associated with treatments, including radiation therapy. The objective of this review article is to present contemporary data on the use of [18F]FDG PET/CT for treatment assessment of aggressive lymphomas.

PET/CT Biomarkers Enable Risk Stratification of Patients with Relapsed/Refractory Diffuse Large B-cell Lymphoma Enrolled in the LOTIS-2 Clinical Trial

PURPOSE

Significant progress has occurred in developing quantitative PET/CT biomarkers in diffuse large B-cell lymphoma (DLBCL). Total metabolic tumor volume (MTV) is the most extensively studied, enabling assessment of FDG-avid tumor burden associated with outcomes. However, prior studies evaluated the outcome of cytotoxic chemotherapy or chimeric antigen receptor T-cell therapy without data on recently approved FDA agents. Therefore, we aimed to assess the prognosis of PET/CT biomarkers in patients treated with loncastuximab tesirine.

EXPERIMENTAL DESIGN

We centrally reviewed screening PET/CT scans of patients with relapsed/refractory DLBCL enrolled in the LOTIS-2 (NCT03589469) study. MTV was obtained by computing individual volumes using the SUV ≥4.0 threshold. Other PET/CT metrics, clinical factors, and the International Metabolic Prognostic Index (IMPI) were evaluated. Logistic regression was used to assess the association between biomarkers and treatment response. Cox regression was used to determine the effect of biomarkers on time-to-event outcomes. We estimated biomarker prediction as continuous and binary variables defined by cutoff points.

RESULTS

Across 138 patients included in this study, MTV with a cutoff point of 96 mL was the biomarker associated with the highest predictive performance in univariable and multivariable models to predict failure to achieve complete metabolic response (OR, 5.42; P = 0.002), progression-free survival (HR, 2.68; P = 0.002), and overall survival (HR, 3.09; P < 0.0001). IMPI demonstrated an appropriate performance, however, not better than MTV alone.

CONCLUSIONS

Pretreatment MTV demonstrated robust risk stratification, with those patients demonstrating high MTV achieving lower responses and survival to loncastuximab tesirine in relapsed/refractory DLBCL.

Prognostic Value of Baseline Tumor Burden and Tumor Dissemination Extracted From 18 F-FDG PET/CT in a Cohort of Adult Patients With Early or Advanced Hodgkin Lymphoma

PURPOSE

We aimed to assess the prognostic value of baseline tumor burden and dissemination parameters extracted from 18 F-FDG PET/CT in patients with early or advanced Hodgkin lymphoma (HL) treated with ABVD (doxorubicin, bleomycin, vinblastine, and dacarbazine) or escalated BEACOPP (increased bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone).

PATIENTS AND METHODS

Patients aged ≥18 years with classical Hodgkin lymphoma were retrospectively included. Progression-free survival (PFS) analysis of dichotomized clinicobiological and PET/CT parameters (SUV max , TMTV, TLG, D max , and D bulk ) was performed. Optimal cutoff values for quantitative metrics were defined as the values maximizing the Youden index from receiver operating characteristic analysis. PFS rates were estimated with Kaplan-Meier curves, and the log-rank test was used to assess statistical significance. Hazard ratios were calculated using Cox proportional hazards models.

RESULTS

With a median age of 32 years, 166 patients were enrolled. A total of 111 patients had ABVD or ABVD-like treatment with or without radiotherapy and 55 patients with escalated BEACOPP treatment. The median follow-up was 55 months. Only International Prognostic Score (IPS >1), TMTV >107 cm 3 , and TLG >1628 were found to be significant prognostic factors for PFS on univariate analysis. Multivariate analysis revealed that IPS and TLG were independently prognostic and, combined, identified 4 risk groups ( P < 0.001): low (low TLG and low IPS; 4-year PFS, 95%), intermediate-low (high IPS and low TLG; 4-year PFS, 79%), intermediate-high (low IPS and high TLG; 4-year PFS, 78%), and high (high TLG and high IPS; 4-year PFS, 71%).

CONCLUSIONS

Combining baseline TLG with IPS could improve PFS prediction.

Prognostic impact of absolute peripheral blood NK cell count after four cycles of R-CHOP-like regimen treatment in patients with diffuse large B cell lymphoma

As a subtype of lymphocyte, natural killer (NK) cell is the first line of defense that shows a strong function in tumor immunotherapy response and clinical outcomes. The current study aims to investigate the prognostic influence of peripheral blood absolute NK cell count after four cycles of rituximab combined with cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) treatment (NKCC4) in diffuse large B cell lymphoma (DLBCL) patients. A total of 261 DLBCL patients treated with R-CHOP from January 2018 to September 2022 were enrolled. The low NKCC4 was observed in patients who died during the study period compared with survival individuals. A NKCC4 < 135 cells/μl had a remarkable negative influence in overall survival and progression-free survival (PFS) compared to a NKCC4 ≥ 135 cells/μl (p < 0.0001 and p < 0.0004, respectively). In addition, the OS and PFS were synergistically lower in a NKCC4 < 135 cells/μl group among DLBCL patients with GCB type or high IPI. In conclusion, this study indicates NCKK4 as a valuable marker in clinical practice and provides an insight for combination treatment of R-CHOP to improve outcomes of DLBCL patients.

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.

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.