Response-adapted frontline therapy for Hodgkin lymphoma: are we there yet?

Influence of the methodological aspects of the dichotomization of total metabolic tumor volume measured through baseline fluorine-18 fluorodeoxyglucose PET on survival prediction in lymphoma

OBJECTIVE

The total metabolic tumor volume (TMTV) measured from fluorine-18 fluorodeoxyglucose (18F-FDG) PET can be useful for determining the prognosis of patients with lymphoma. Stratifying patients into high- and low-TMTV risk groups requires a cutoff point, which is determined through the dichotomization method. This study investigated whether different TMTV dichotomization methods influenced survival prediction in patients with lymphoma.

METHODS

We retrospectively enrolled 129 patients with lymphoma who had undergone baseline 18F-FDG PET. TMTV was calculated using a fixed standardized uptake value threshold of 4.0. A total of six methods were employed to determine the optimal TMTV cutoff point using receiver-operating characteristic curve analyses, X-Tile bioinformatics software, and the Cutoff Finder web application. The prognostic performance of each method in survival prediction was examined.

RESULTS

The median (interquartile range) TMTV was 123 cm3 (21-335 cm3). The optimal TMTV cutoff values for predicting progression-free survival (PFS) and overall survival (OS) were in the range of 144-748 cm3. The cutoff points were used to dichotomize patients into two groups with distinct prognoses. All TMTV dichotomizations were significantly predictive of PFS and OS. The survival curves showed significant differences between the high- and low-TMTV groups. The C-indices of the survival models did not significantly differ in any of the dichotomizations.

CONCLUSION

The prognostic significance of TMTV was maintained regardless of the methodological aspects of dichotomization. However, the optimal TMTV cutoff point varied according to the chosen dichotomization method. Care should be taken when establishing an optimal TMTV cutoff point for clinical use.

The future of cell-free DNA testing to guide therapeutic decisions in B-cell lymphomas

PURPOSE OF REVIEW

Tissue biopsy is the current gold standard technique for diagnosis and molecular profiling of lymphomas, but it carries several disadvantages in terms of procedural risks (infectious and haemorrhagic complications, anaesthesiologic risks) and analytic aspects (heterogeneity of tumors, low representation of tumor cells in the tissue). Noninvasive genotyping of B-cell lymphomas through circulating tumor DNA (ctDNA) is emerging as a practical tool to monitor the genetics and course of the disease from diagnosis to eventual relapse.This review will explore recent advances in the field of liquid biopsy in lymphomas, highlighting their clinical implications.

RECENT FINDINGS

ctDNA has been recently proposed an alternative source of tumor DNA for genotyping purposes, especially for those samples having low tumor representation or when longitudinal genetic monitoring is limited by the inaccessibility of relapsed tumor tissues. Also, ctDNA has been recently proposed radiation-free tool for the early identification of chemorefractory lymphoma patients.

SUMMARY

The detection of ctDNA circulating in the bloodstream of lymphoma patients can inform about the genetics of the disease at diagnosis identifying druggable alterations, detect the onset of mutation of resistance during treatment, anticipate about relapse earlier than standard methods [e.g. PET associated with computed tomography (PET/CT)] during follow-up.

Re-defining Prognosis of Hematological Malignancies by Dynamic Response Assessment Methods: Lessons Learnt in Chronic Myeloid Leukemia, Hodgkin Lymphoma, Diffuse Large B Cell Lymphoma and Multiple Myeloma

Risk-stratification is an essential management tool in defining prognosis of haematological neoplasms, both from patient and physician perspective. We define a new prognostic term "Dynamic Response Assessment Method(s) (DRAM)" as "method(s) used for re-stratifying disease prognosis at fixed intervals during the treatment course". The risk stratification is done after a fixed duration of treatment or chemotherapy cycles using sensitive techniques. The information obtained then can be used for further therapeutic decisions and prognostication. Currently, there is enough evidence that response to treatment improves the prognostic value of baseline disease variables in the management of Chronic Myeloid Leukemia, Hodgkin lymphoma, Diffuse Large B cell Lymphoma, and Multiple Myeloma. Through this review, we discuss the current evidence based application of "DRAM" to guide therapeutic decisions in these malignancies. We also discuss how the results of "DRAM" can be incorporated for redefining prognosis and counselling the patients with these selected hematologic malignancies.

Novel Biomarker Approaches in Classic Hodgkin Lymphoma

Classic Hodgkin lymphoma (cHL) is one of the most common lymphomas in the Western world. Advances in the management of cHL have led to high cure rates exceeding 80%. Nevertheless, relapse or refractory disease in a subset of patients and treatment-related toxicity still represents unsolved clinical problems. The introduction of targeted treatments such as PD-1 blockade and the CD30 antibody drug conjugate, brentuximab vedotin, has broadened treatment options in cHL, emphasizing the critical need to identify biomarkers with the goal to provide rationales for treatment selection, increase effective drug utilization, and minimize toxicity. The unique biology of cHL featuring low abundant tumor cells and numerous nonmalignant immune cells in the tumor microenvironment can provide various types of promising biomarkers related to the tumor cells directly, tumor microenvironment cross-talk, and host immune response. Here, we comprehensively review novel biomarkers including circulating tumor DNA and gene expression-based prognostic models that might guide the ideal management of cHL in the future.

MRI and PET/MRI in hematologic malignancies

The role of MRI differs considerably between the three main groups of hematological malignancies: lymphoma, leukemia, and myeloma. In myeloma, whole‐body MRI (WB‐MRI) is recognized as a highly sensitive test for the assessment of myeloma, and is also endorsed by clinical guidelines, especially for detection and staging. In lymphoma, WB‐MRI is presently not recommended, and merely serves as an alternative technique to the current standard imaging test, [¹⁸F]FDG‐PET/CT, especially in pediatric patients. Even for lymphomas with variable FDG avidity, such as extranodal mucosa‐associated lymphoid tissue lymphoma (MALT), contrast‐enhanced computed tomography (CT), but not WB‐MRI, is presently recommended, despite the high sensitivity of diffusion‐weighted MRI and its ability to capture treatment response that has been reported in the literature. In leukemia, neither MRI nor any other cross‐sectional imaging test (including positron emission tomography [PET]) is currently recommended outside of clinical trials. This review article discusses current clinical applications as well as the main research topics for MRI, as well as PET/MRI, in the field of hematological malignancies, with a focus on functional MRI techniques such as diffusion‐weighted imaging and dynamic contrast‐enhanced MRI, on the one hand, and novel, non‐FDG PET imaging probes such as the CXCR4 radiotracer [⁶⁸Ga]Ga‐Pentixafor and the amino acid radiotracer [¹¹C]methionine, on the other hand.

Level of Evidence: 5

Technical Efficacy Stage: 3

J. Magn. Reson. Imaging 2020;51:1325–1335.

FDA's and EMA's approval of brentuximab vedotin for advanced Hodgkin lymphoma: Another player in the town?

ECHELON-1 study is a randomized open-labeled controlled trial investigating whether addition of brentuximab vedotin to chemotherapy offers benefit over the standard chemotherapy regimen in advanced Hodgkin lymphoma. After a median follow-up of 24.6 months, it has met its primary endpoint the reduction of modified progression-free survival being 23 percent. However, the beneficial effects have not been seen across all subgroups leading to further questions. The main aim of this review is to tackle these questions to provide the reader with in-depth insight of pros and cons of this novel, promising but ultimately controversial regimen.

Pervasive mutations of JAK-STAT pathway genes in classical Hodgkin lymphoma

Dissecting the pathogenesis of classical Hodgkin lymphoma (cHL), a common cancer in young adults, remains challenging because of the rarity of tumor cells in involved tissues (usually <5%). Here, we analyzed the coding genome of cHL by microdissecting tumor and normal cells from 34 patient biopsies for a total of ∼50 000 singly isolated lymphoma cells. We uncovered several recurrently mutated genes, namely, STAT6 (32% of cases), GNA13 (24%), XPO1 (18%), and ITPKB (16%), and document the functional role of mutant STAT6 in sustaining tumor cell viability. Mutations of STAT6 genetically and functionally cooperated with disruption of SOCS1, a JAK-STAT pathway inhibitor, to promote cHL growth. Overall, 87% of cases showed dysregulation of the JAK-STAT pathway by genetic alterations in multiple genes (also including STAT3, STAT5B, JAK1, JAK2, and PTPN1), attesting to the pivotal role of this pathway in cHL pathogenesis and highlighting its potential as a new therapeutic target in this disease.

Early Chemotherapy Intensification With Escalated BEACOPP in Patients With Advanced-Stage Hodgkin Lymphoma With a Positive Interim Positron Emission Tomography/Computed Tomography Scan After Two ABVD Cycles: Long-Term Results of the GITIL/FIL HD 0607 Trial

Purpose

To investigate the progression-free survival (PFS) of patients with advanced Hodgkin lymphoma (HL) after a risk-adapted treatment strategy that was based on a positive positron emission tomography scan performed after two doxorubicin, vinblastine, vincristine, and dacarbazine (ABVD) cycles (PET2).

Patients and Methods

Patients with advanced-stage (IIB to IVB) HL were consecutively enrolled. After two ABVD cycles, PET2 was performed and centrally reviewed according to the Deauville five-point scale. Patients with a positive PET2 were randomly assigned to four cycles of escalated bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (BEACOPP) followed by four cycles of standard BEACOPP with or without rituximab. Patients with a negative PET2 continued ABVD, and those with a large nodal mass at diagnosis (≥ 5 cm) in complete remission with a negative PET at the end of chemotherapy were randomly assigned to radiotherapy or no further treatment. The primary end point was 3-year PFS.

Results

Of 782 enrolled patients, 150 (19%) had a positive and 630 (81%) a negative PET2. The 3-year PFS of all patients was 82%. The 3-year PFS of those with a positive and negative PET2 was 60% and 87%, respectively ( P < .001). The 3-year PFS of patients with a positive PET2 assigned to BEACOPP with or without rituximab was 63% versus 57% ( P = .53). In 296 patients with both interim and post-ABVD–negative PET who had a large nodal mass at diagnosis, radiotherapy was randomly added after chemotherapy without a significant PFS improvement (97% v 93%, respectively; P = .29). The 3-year overall survival of all 782 patients was 97% (99% and 89% for PET2 negative and positive, respectively).

Conclusion

The PET-driven switch from ABVD to escalated BEACOPP is feasible and effective in high-risk patients with advanced-stage HL.

18F-FDG PET/CT in Lymphoma: Has Imaging-Directed Personalized Medicine Become a Reality?

PET/CT using ¹⁸F-FDG is an essential part of the management of patients with lymphoma. 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. PET-guided therapy has improved outcomes in Hodgkin lymphoma, using less chemotherapy and more selective radiotherapy. Attempts to intensify chemotherapy in aggressive non-Hodgkin lymphomas have, however, proved ineffective in patients treated with rituximab and chemotherapy. Trials are under way to determine whether PET can obviate consolidation radiotherapy in patients with diffuse large B-cell lymphoma and primary mediastinal B-cell lymphoma. More recently, PET has been reported to be a reliable predictor of outcome in follicular lymphoma requiring treatment, and prospective trials to test PET-guided therapy in this disease are anticipated.

FDG PET for therapy monitoring in Hodgkin and non-Hodgkin lymphomas

PET using 18F-FDG for treatment monitoring in patients with lymphoma is one of the most well-developed clinical applications. PET/CT is nowadays used during treatment to assess chemosensitivity, with response-adapted therapy given according to 'interim' PET in clinical practice to adults and children with Hodgkin lymphoma. PET is also used to assess remission from disease and to predict prognosis in the pretransplant setting. Mature data have been reported for the common subtypes of aggressive B-cell lymphomas, with more recent data also supporting the use of PET for response assessment in T-cell lymphomas. The Deauville five-point scale incorporating the Deauville criteria (DC) is recommended for response assessment in international guidelines. FDG uptake is graded in relation to the reference regions of normal mediastinum and liver. The DC have been validated in most lymphoma subtypes. The DC permit the threshold for adequate or inadequate response to be adapted according to the clinical context or research question. It is important for PET readers to understand how the DC have been applied in response-adapted trials for correct interpretation and discussion with the multidisciplinary team. Quantitative methods to perform PET in standardized ways have also been developed which may further improve response assessment including a quantitative extension to the DC (qPET). This may have advantages in providing a continuous scale to refine the threshold for adequate/inadequate response in specific clinical situations or treatment optimization in trials. qPET is also less observer-dependent and limits the problem of optical misinterpretation due to the influence of background activity.