Circulating tumor DNA in B-cell lymphoma: technical advances, clinical applications, and perspectives for translational research

Circulating Tumor DNA as a Complementary Prognostic Biomarker during CAR-T Therapy in B-Cell Non-Hodgkin Lymphomas

The emergence of CD19-directed chimeric antigen receptor T-cell (CAR-T) therapy has revolutionized the treatment paradigm for R/R B-cell NHLs. However, challenges persist in accurately evaluating treatment response and detecting early relapse, necessitating the exploration of novel biomarkers. Circulating tumor DNA (ctDNA) via liquid biopsy is a non-invasive tool for monitoring therapy efficacy and predicting treatment outcomes in B-NHL following CAR-T therapy. By overcoming the limitations of conventional imaging modalities, ctDNA assessments offer valuable insights into response dynamics, molecular mechanisms of resistance, and early detection of molecular relapse. Integration of ctDNA monitoring into clinical practice holds promise for personalized therapeutic strategies, guiding the development of novel targeted therapies, and enhancing patient outcomes. However, standardization of assay methodologies and consensus on clinical response metrics are imperative to unlock the full potential of ctDNA in the management of B-NHL. Prospective validation of ctDNA in clinical trials is necessary to establish its role as a complementary decision aid.

Optimization of immune checkpoint inhibitor treatment planning for relapsed or refractory extranodal NK/T cell lymphoma

Pembrolizumab (anti-programmed cell death-ligand 1 inhibitor) is a promising salvage therapeutic option for relapsed/refractory extranodal NK/T-cell lymphoma (R/R ENKTL). However, the appropriate duration of pembrolizumab use in R/R ENKTL patients and the optimal timing for administering pembrolizumab remain undetermined. We collected and analyzed clinical information on R/R ENKTL 58 patients who received pembrolizumab to evaluate the optimal treatment durations and clinical information for considering treatment interruption. Treatment outcomes were assessed by 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) and Epstein Barr virus DNA (EBV DNA) every 3 months. Nineteen (32.8%) patients had been treated with more than three chemotherapies before pembrolizumab administration. The best response rate towards the first try of pembrolizumab was 38.9% (31.5% complete response rate (CR), 7.4% partial response (PR)). During the 41.8-month median follow-up duration, the median progression-free survival (PFS) was 3.1 months, and the median overall survival (OS) was 7.1 months. The failure group, which was characterized by Deaville score (DS) 3-4 and circulating EBV detection, or DS 5 with/without EBV detection, had the worst PFS (p < 0.001) and OS (p < 0.001), followed by the high (DS 1-2 and EBV detection, or DS 3-4 and EBV not detected) and low-risk groups (DS 1-2 and EBV not detected). Among the 21 patients who achieved the best response at the first pembolizumab try, the patients who received planned 24 cycles presented better PFS than those who received incomplete cycles (57.6 months vs 20.9 months, P-value = 0.012). Among 13 patients who received avelumab or pembrolizumab in advance, a few who responded to the second trial of pembrolizumab administration had over one year of chemotherapy vacation. Determining the discontinuation or continuation of pembrolizumab would be considered in selected cases assessed by PET-CT and EBV monitoring. Disruption of pembrolizumab treatment may be advisable for the low-risk group(DS 1-2 and EBV not detected), whereas continuation could be warranted for the high-risk group (DS 1-2 and EBV detection, or DS 3-4 and EBV not detected). Moreover, it might be critical to maintain over 24 cycles to improve the survival outcome of R/R ENKTL.

Application of the Central Nervous System International Prognostic Index (CNS-IPI) score in daily practice: a retrospective analysis apart from the clinical trial at two centers in Brazil

INTRODUCTION

The diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL) and, despite all the progress in this field, central nervous system infiltration (CNSi) still occurs at an incidence of 2-10%. The objective of the present study was to evaluate the Central Nervous System International Prognostic Index (CNS-IPI) score in daily practice regarding the reproducibility in a heterogeneous cohort apart from a clinical trial.

METHODS

Primary DLBCL patients were eligible for this study, between January 2007 and January 2017. All patients were treated with rituximab-based chemotherapy, mostly R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone). The CNSi was diagnosed by liquor (positive cytology and/or immunophenotype), computerized tomography, magnetic resonance image and/or fluorodeoxy-glucose-positron emission tomography, requested only in symptomatic patients when the CNSi was clinically suspected. The CNS-IPI was assessed by graphical comparison and calibration.

RESULTS

After applying the inclusion/exclusion criteria, 322 patients were available for the analysis. The median follow-up was 60 months and the median age was 58 years. Seven patients experienced CNSi, characterizing an incidence of 2.17% (7/322). Comparing groups of patients with and without CNSi, we observed that the lactate dehydrogenase (LDH), number of extranodal sites, IPI, kidney/adrenal and absence of complete response were statistically different. The CNS-IPI model stratified patients in a three-risk group model as low-, intermediate- and high-risk. In our cohort, using the same stratification, we obtained an equivalent the 2-year rate of CNS relapse of 0.0%, 0.8% and 13.8%, respectively.

CONCLUSION

Our study reinforces the reproducibility of the CNS-IPI, specifically apart from clinical trials, and suggests the CNS-IPI score as a tool to guide therapy.

Richter's transformation: Transforming the clinical landscape

Richter transformation (RT) represents an aggressive histological transformation from chronic lymphocytic leukaemia, most often to a large B cell lymphoma. It is characterised by chemo-resistance and subsequent short survival. Drug development has struggled over recent years in light of the aggressive kinetics of the disease, lack of pivotal registrational trials and relative rarity of the phenomenon. In this review we will highlight the diagnostic and therapeutic challenges of managing patients with RT as well as taking a look to the future therapeutic landscape. Highly active therapies developed across B cell malignancies are starting to impact this field, with T-cell activation therapies (CAR-T, bispecific antibodies), antibody-drug conjugates, and novel small molecule inhibitor combinations (e.g. BTKi-BCL2i) being actively studied. We will highlight the data supporting these developments and look to the studies to come to provide hope for patients suffering from this devastating disease.

Improved early outcome prediction by MRI-based 3D tumor volume assessment in patients with CNS lymphomas

BACKGROUND

Central nervous system lymphomas (CNSL) display remarkable clinical heterogeneity, yet accurate prediction of outcomes remains challenging. The IPCG criteria are widely used in routine practice for the assessment of treatment response. However, the value of the IPCG criteria for ultimate outcome prediction is largely unclear, mainly due to the uncertainty in delineating complete from partial responses during and after treatment.

METHODS

We explored various MRI features including semi-automated 3D tumor volume measurements at different disease milestones and their association with survival in 93 CNSL patients undergoing curative-intent treatment.

RESULTS

At diagnosis, patients with more than 3 lymphoma lesions, periventricular involvement, and high 3D tumor volumes showed significantly unfavorable PFS and OS. At first interim MRI during treatment, the IPCG criteria failed to discriminate outcomes in responding patients. Therefore, we randomized these patients into training and validation cohorts to investigate whether 3D tumor volumetry could improve outcome prediction. We identified a 3D tumor volume reduction of ≥97% as the optimal threshold for risk stratification (=3D early response, 3D_ER). Applied to the validation cohort, patients achieving 3D_ER had significantly superior outcomes. In multivariate analyses, 3D_ER was independently prognostic of PFS and OS. Finally, we leveraged prognostic information from 3D MRI features and circulating biomarkers to build a composite metric that further improved outcome prediction in CNSL.

CONCLUSIONS

We developed semi-automated 3D tumor volume measurements as strong and independent early predictors of clinical outcomes in CNSL patients. These radiologic features could help improve risk stratification and help guide future treatment approaches.

SOHO State-of-the-Art Updates and Next Questions: Treatment for Newly Diagnosed Peripheral T-Cell Lymphomas

Although a rare subset of non-Hodgkin lymphomas, peripheral T-cell lymphomas (PTCL) account for a disproportionate proportion of patient mortality. Conventional therapies are derived from experience treating aggressive B-cell lymphomas and center around CHOP-based chemotherapy. However, due to the unique biology and diverse subtypes of PTCL, most patients fail to durably respond to this approach and 5-year survival is only 20% to 30%. There have been multiple attempts to improve outcomes for patients with PTCL. Among the more successful strategies are the use of consolidative autologous stem cell transplant, the augmentation of CHOP with etoposide (CHOEP), and the use of brentuximab vedotin in CD30-positive PTCL. Advances in the understanding of histology-specific biology has cultivated enthusiasm to evaluate hypomethylating agents, histone deacetylate inhibitors, and phosphoinositol-3-kinase inhibitors in the frontline setting. Improvements in monitoring disease response and prognostication including the use of cell-free DNA, mutational profiling, and interim PET/CT imaging are also on the horizon. For patients with acute T-cell leukemia/lymphoma, the use of mogamulizumab-based therapy in the frontline setting may lead to advances in care. The true impact of these new-era therapies will only be elucidated as clinical practices incorporate the rapidly changing evidence.

Cell-Free DNA as a Biomarker at Diagnosis and Follow-Up in 256 B and T-Cell Lymphomas

BACKGROUND

Cell-free DNA (cfDNA) analysis has become a promising tool for the diagnosis, prognosis, and monitoring of lymphoma cases. Until now, research in this area has mainly focused on aggressive lymphomas, with scanty information from other lymphoma subtypes.

METHODS

We selected 256 patients diagnosed with lymphomas, including a large variety of B-cell and T-cell non-Hodgkin and Hodgkin lymphomas, and quantified cfDNA from plasma at the time of diagnosis. We further selected 49 large B-cell lymphomas (LBCL) and analyzed cfDNA levels at diagnosis (pre-therapy) and after therapy. In addition, we performed NGS on cfDNA and tissue in this cohort of LBCL.

RESULTS

Lymphoma patients showed a statistically significant higher cfDNA concentration than healthy controls (mean 53.0 ng/mL vs. 5.6 ng/mL, p < 0.001). The cfDNA concentration was correlated with lymphoma subtype, lactate dehydrogenase, the International Prognostic Index (IPI) score, Ann Arbor (AA), and B-symptoms. In 49 LBCL cases, the cfDNA concentration decreased after therapy in cases who achieved complete response (CR) and increased in non-responders. The median cfDNA at diagnosis of patients who achieved CR and later relapsed was higher (81.5 ng/mL) compared with levels of those who did not (38.6 ng/mL). A concordance of 84% was observed between NGS results in tumor and cfDNA samples. Higher VAF in cfDNA is correlated with advanced stage and bulky disease.

CONCLUSIONS

cfDNA analysis can be easily performed in almost all lymphoma cases. The cfDNA concentration correlated with the characteristics of the aggressiveness of the lymphomas and, in LBCL, with the response achieved after therapy. These results support the utility of cfDNA analysis as a complementary tool in the management of lymphoma patients.

Circulating-tumor DNA Assessment in Diffuse Large B-cell Lymphoma to Determine Up-front Stem Cell Transplantation: A Pilot Study

BACKGROUND/AIM

This study evaluated the possibility of clinical use of circulating-tumor DNA (ctDNA) as a biomarker to determine up-front autologous stem cell transplantation (auto-SCT) for patients with high-risk diffuse large B-cell lymphoma (DLBCL) in practice.

PATIENTS AND METHODS

To explore the dynamics of ctDNA in DLBCL, blood samples were collected sequentially before and after treatment from patients with newly diagnosed DLBCL who received rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) chemotherapy. To conduct ctDNA genotyping and ctDNA monitoring simultaneously, targeted sequencing by cancer personalized profiling using deep sequencing was used.

RESULTS

Ten patients between the ages of 50 and 60 years were enrolled. Based on the international prognostic index (IPI), seven patients were classified as high-IPI-risk group, and three patients were classified as low-IPI-risk group. The IPI risk group correlated with total metabolic tumor volume. All patients completed six cycles of R-CHOP chemotherapy, and seven patients achieved complete response. Changes in ctDNA mutation numbers did not correlate with changes in PET scan images and treatment response. In most high-risk patients, new mutations appeared in ctDNA after completion of chemotherapy that conceivably marked resistant clones. Notably, disease relapse did not occur in high-risk patients with poor prognostic mutations who underwent autologous SCT.

CONCLUSION

ctDNA monitoring was meaningful in high-risk patients. Moreover, ctDNA and well-known prognostic factors should be considered in the decision making for auto-SCT. If a new genetic mutation in ctDNA with a negative prognosis would emerge during treatment, high-risk patients should consider auto-SCT.

Circulating Tumor DNA Reflects Histologic and Clinical Characteristics of Various Lymphoma Subtypes

PURPOSE

We designed and evaluated the clinical performance of a plasma circulating tumor DNA (ctDNA) panel of 112 genes in various subtypes of lymphoma.

MATERIALS AND METHODS

Targeted deep sequencing with an error-corrected algorithm was performed in ctDNA from plasma samples that were collected before treatment in 42 lymphoma patients. Blood buffy coat was utilized as a germline control. We evaluated the targeted gene panel using mutation detection concordance on the plasma samples with matched tissue samples analyzed the mutation profiles of the ctDNA.

RESULTS

Next-generation sequencing analysis using matched tissue samples was available for 18 of the 42 patients. At least one mutation was detected in the majority of matched tissue biopsy samples (88.9%) and plasma samples (83.3%). A considerable number of mutations (40.4%) that were detected in the tissue samples were also found in the matched plasma samples. Majority of patients (21/42) were diffuse large B cell lymphoma patients. The overall detection rate of ctDNA in patients was 85.7% (36/42). The frequently mutated genes included PIM1, TET2, BCL2, KMT2D, KLHL6, HIST1H1E, and IRF8. A cutoff concentration (4,506 pg/mL) of ctDNA provided 88.9% sensitivity and 82.1% specificity to predict ctDNA mutation detection. The ctDNA concentration correlated with elevated lactate dehydrogenase level and the disease stage.

CONCLUSION

Our design panel can detect many actionable gene mutations, including those at low frequency. Therefore, liquid biopsy can be applied clinically in the evaluation of lymphoma patients, especially in aggressive lymphoma patients.

Subcutaneous epcoritamab monotherapy in Japanese adults with relapsed/refractory diffuse large B-cell lymphoma

Epcoritamab is a subcutaneously administered CD3xCD20 bispecific Ab that showed deep, durable responses with a manageable safety profile in patients with relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL) in the global multicenter pivotal phase II trial EPCORE NHL-1. Here, we present results from the similar EPCORE NHL-3 phase I/II trial evaluating epcoritamab monotherapy in Japanese patients with R/R CD20+ B-cell non-Hodgkin's lymphoma previously treated with two or more lines of therapy. Epcoritamab was dosed subcutaneously in 28-day cycles; once weekly during cycles 1-3, every 2 weeks during cycles 4-9, and every 4 weeks from cycle 10 until disease progression or unacceptable toxicity. Step-up dosing and cytokine release syndrome (CRS) prophylaxis were used during treatment cycle 1. As of January 31, 2022, 36 patients received treatment with 48 mg epcoritamab monotherapy. At a median follow-up of 8.4 months, overall response and complete response rates by independent review committee were 55.6% and 44.4%, respectively. The median duration of response, duration of complete response, and overall survival were not reached at the time of data cut-off. The most common treatment-emergent adverse events of any grade were CRS (83.3%), injection-site reactions (69.4%), infections (44.4%), neutropenia (38.9%), hypokalemia (27.8%), and decreased lymphocyte count (25.0%). Cytokine release syndrome occurrence was predictable; events were primarily low grade (grade 1-2), all resolved, and none led to treatment discontinuation. These encouraging results are consistent with previous findings and support the ongoing clinical evaluation of epcoritamab for the treatment of R/R DLBCL, including in earlier treatment lines.

2024 Update: Advances in the risk stratification and management of large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease with varying clinical outcomes. Our understanding of its molecular makeup continues to improve risk stratification, and artificial-intelligence and ctDNA-based analyses have the potential to enhance risk assessment and disease monitoring. R-CHOP and Pola-R-CHP are used in the frontline setting; chimeric antigen receptor therapy (CART) is now the new standard-of-care for most with primary refractory disease; both CART and autologous stem cell transplantation are utilized in the relapsed and refractory setting. In this review, we summarize the classification and management of DLBCL with an emphasis on recent advances in the field.

Parallel testing of liquid biopsy (ctDNA) and tissue biopsy samples reveals a higher frequency of EZH2 mutations in follicular lymphoma

BACKGROUND

Recent genomic studies revealed enhancer of zeste homolog 2 (EZH2) gain-of-function mutations, representing novel therapeutic targets in follicular lymphoma (FL) in around one quarter of patients. However, these analyses relied on single-site tissue biopsies and did not investigate the spatial heterogeneity and temporal dynamics of these alterations.

OBJECTIVES

We aimed to perform a systematic analysis of EZH2 mutations using paired tissue (tumor biopsies [TB]) and liquid biopsies (LB) collected prior to treatment within the framework of a nationwide multicentric study.

METHODS

Pretreatment LB and TB samples were collected from 123 patients. Among these, 114 had paired TB and LB, with 39 patients characterized with paired diagnostic and relapse samples available. The EZH2 mutation status and allele burden were assessed using an in-house-designed, highly sensitive multiplex droplet digital PCR assay.

RESULTS

EZH2 mutation frequency was found to be 41.5% in the entire cohort. In patients with paired TB and LB samples, EZH2 mutations were identified in 37.8% of the patients with mutations exclusively found in 5.3% and 7.9% of TB and LB samples, respectively. EZH2 mutation status switch was documented in 35.9% of the patients with paired diagnostic and relapse samples. We also found that EZH2 wild-type clones may infiltrate the bone marrow more frequently compared to the EZH2 mutant ones.

CONCLUSION

The in-depth spatio-temporal analysis identified EZH2 mutations in a considerably higher proportion of patients than previously reported. This expands the subset of FL patients who most likely would benefit from EZH2 inhibitor therapy.

Genetic Profiling of Cell-Free DNA in Liquid Biopsies: A Complementary Tool for the Diagnosis of B-Cell Lymphomas and the Surveillance of Measurable Residual Disease

PURPOSE

To assess the potential value of LiqBio as a complementary tool for diagnosis and surveillance of BCL.

METHODS

This prospective multi-center study included 78 patients (25 follicular lymphomas (FL) and 53 large B-cell lymphomas (LBCL)). We performed next-generation sequencing (NGS) of cfDNA LiqBio and paired gDNA tissue biopsies at diagnosis and compared the mutational statuses. Also, through NGS of LiqBio, we identified MRD biomarkers and compared this novel LiqBio-MRD method with PET/CT in detecting MRD at follow-up.

RESULTS

We identified mutations in 71% of LiqBio and 95% of tissue biopsies, and found a correlation between variant allele frequency of somatic mutations. Additionally, we identified mutations in 73% of LiqBio from patients with no available tissue samples or no mutations in them. Regarding the utility of LiqBio-MRD as a dynamic monitoring tool, when compared with the PET/CT method, a lower sensitivity was observed for LiqBio-MRD at 92.3% (vs. 100% for PET/CT), but a higher specificity of 91.3% (vs. 86.9% for PET/CT).

CONCLUSION

Genetic profiling of tumor cfDNA in plasma LiqBio is a complementary tool for BCL diagnosis and MRD surveillance.

Molecular associations of response to the new-generation BTK inhibitor zanubrutinib in marginal zone lymphoma

Using tissue whole exome sequencing (WES) and circulating tumor cell-free DNA (ctDNA), this Australasian Leukaemia & Lymphoma Group translational study sought to characterize primary and acquired molecular determinants of response and resistance of marginal zone lymphoma (MZL) to zanubrutinib for patients treated in the MAGNOLIA clinical trial. WES was performed on baseline tumor samples obtained from 18 patients. For 7 patients, ctDNA sequence was interrogated using a bespoke hybrid-capture next-generation sequencing assay for 48 targeted genes. Somatic mutations were correlated with objective response data and survival analysis using Fisher exact test and Kaplan-Meier (log-rank) method, respectively. Baseline WES identified mutations in 33 of 48 (69%) prioritized genes. NF-κB, NOTCH, or B-cell receptor (BCR) pathway genes were implicated in samples from 16 of 18 patients (89%). KMT2D mutations (n = 11) were most common, followed by FAT1 (n = 9), NOTCH1, NOTCH2, TNFAIP3 (n = 5), and MYD88 (n = 4) mutations. MYD88 or TNFAIP3 mutations correlated with improved progression-free survival (PFS). KMT2D mutations trended to worse PFS. Acquired resistance mutations PLCG2 (R665W/R742P) and BTK (C481Y/C481F) were detected in 2 patients whose disease progressed. A BTK E41K noncatalytic activating mutation was identified before treatment in 1 patient who was zanubrutinib-refractory. MYD88, TNFAIP3, and KMT2D mutations correlate with PFS in patients with relapsed/refractory MZL treated with zanubrutinib. Detection of acquired BTK and PLCG2 mutations in ctDNA while on therapy is feasible and may herald clinical disease progression. This trial was registered at https://anzctr.org.au/ as #ACTRN12619000024145.

Clinical applications of circulating tumor DNA in central nervous system lymphoma

Detection and characterization of circulating tumor DNA (ctDNA) in body fluids have the potential to revolutionize management of patients with lymphoma. Minimal access to malignant DNA through a simple blood draw or lumbar puncture is particularly appealing for CNS lymphomas (CNSL), which cannot be easily or repeatedly sampled without invasive surgeries. Profiling of ctDNA provides a real-time snapshot of the genetic composition in patients with CNSL and enables ultrasensitive quantification of lymphoma burden at any given time point during the course of the disease. Here, we broadly review technical challenges of ctDNA identification in CNSL, recent advances of innovative liquid biopsy technologies, potential clinical applications of ctDNA and how it may improve CNSL risk stratification, outcome prediction, and monitoring of measurable residual disease. Finally, we discuss clinical trials and scenarios in which ctDNA could be implemented to guide risk-adapted and personalized treatment decisions.

Whole-genome informed circulating tumor DNA analysis by multiplex digital PCR for disease monitoring in B-cell lymphomas: a proof-of-concept study

Introduction

Analyzing liquid biopsies for tumor-specific aberrations can facilitate detection of measurable residual disease (MRD) during treatment and at follow-up. In this study, we assessed the clinical potential of using whole-genome sequencing (WGS) of lymphomas at diagnosis to identify patient-specific structural (SVs) and single nucleotide variants (SNVs) to enable longitudinal, multi-targeted droplet digital PCR analysis (ddPCR) of cell-free DNA (cfDNA).

Methods

In 9 patients with B-cell lymphoma (diffuse large B-cell lymphoma and follicular lymphoma), comprehensive genomic profiling at diagnosis was performed by 30X WGS of paired tumor and normal specimens. Patient-specific multiplex ddPCR (m-ddPCR) assays were designed for simultaneous detection of multiple SNVs, indels and/or SVs, with a detection sensitivity of 0.0025% for SV assays and 0.02% for SNVs/indel assays. M-ddPCR was applied to analyze cfDNA isolated from serially collected plasma at clinically critical timepoints during primary and/or relapse treatment and at follow-up.

Results

A total of 164 SNVs/indels were identified by WGS including 30 variants known to be functionally relevant in lymphoma pathogenesis. The most frequently mutated genes included KMT2D, PIM1, SOCS1 and BCL2. WGS analysis further identified recurrent SVs including t(14;18)(q32;q21) (IGH::BCL2), and t(6;14)(p25;q32) (IGH::IRF4). Plasma analysis at diagnosis showed positive circulating tumor DNA (ctDNA) levels in 88% of patients and the ctDNA burden correlated with baseline clinical parameters (LDH and sedimentation rate, p-value <0.01). While clearance of ctDNA levels after primary treatment cycle 1 was observed in 3/6 patients, all patients analyzed at final evaluation of primary treatment showed negative ctDNA, hence correlating with PET-CT imaging. One patient with positive ctDNA at interim also displayed detectable ctDNA (average variant allele frequency (VAF) 6.9%) in the follow-up plasma sample collected 2 years after final evaluation of primary treatment and 25 weeks before clinical manifestation of relapse.

Conclusion

In summary, we demonstrate that multi-targeted cfDNA analysis, using a combination of SNVs/indels and SVs candidates identified by WGS analysis, provides a sensitive tool for MRD monitoring and can detect lymphoma relapse earlier than clinical manifestation.

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).

Liquid biopsy in hematological malignancies: current and future applications

The assessment of the cancer mutational profile is crucial for patient management, stratification, and therapeutic decisions. At present, in hematological malignancies with a solid mass, such as lymphomas, tumor genomic profiling is generally performed on the tissue biopsy, but the tumor may harbor genetic lesions that are unique to other anatomical compartments. The analysis of circulating tumor DNA (ctDNA) on the liquid biopsy is an emerging approach that allows genotyping and monitoring of the disease during therapy and follow-up. This review presents the different methods for ctDNA analysis and describes the application of liquid biopsy in different hematological malignancies. In diffuse large B-cell lymphoma (DLBCL) and Hodgkin lymphoma (HL), ctDNA analysis on the liquid biopsy recapitulates the mutational profile of the tissue biopsy and can identify mutations otherwise absent on the tissue biopsy. In addition, changes in the ctDNA amount after one or two courses of chemotherapy significantly predict patient outcomes. ctDNA analysis has also been tested in myeloid neoplasms with promising results. In addition to mutational analysis, liquid biopsy also carries potential future applications of ctDNA, including the analysis of ctDNA fragmentation and epigenetic patterns. On these grounds, several clinical trials aiming at incorporating ctDNA analysis for treatment tailoring are currently ongoing in hematological malignancies.

Measurable Residual Disease After CAR T-Cell Therapy

Testing for measurable residual disease (MRD) provides important prognostic and predictive implications on survival and management of many hematologic diseases. Among the many clinical uses of MRD is post-therapy response assessment and risk stratification. With the integration of precision medicine in routine clinical care and the development of novel and innovative therapies resulting in deeper responses, it is necessary to refine the role of MRD, standardize available methodologies and define its role as a surrogate endpoint for relapse and time-to-next treatment in clinical studies. Chimeric Antigen Receptor (CAR) T-cell therapy is an approved treatment for various hematologic malignancies. Even though it produces high rates of remission, the durability of response is still a consideration as almost 40% to 50% of patients eventually relapse. MRD testing as a prognostic and surrogate marker is being explored in patients after CAR T-cell therapy to predict early relapse. In this chapter, we review the various tools available for MRD detection and monitoring post-CAR T-cell therapy. We later discuss disease-specific MRD assessment and its application in recent studies in the post-CAR T setting.

Primary refractory plasmablastic lymphoma: A precision oncology approach

Introduction

Hematologic malignancies are currently underrepresented in multidisciplinary molecular-tumor-boards (MTB). This study assesses the potential of precision-oncology in primary-refractory plasmablastic-lymphoma (prPBL), a highly lethal blood cancer.

Methods

We evaluated clinicopathological and molecular-genetic data of 14 clinically annotated prPBL-patients from initial diagnosis. For this proof-of-concept study, we employed our certified institutional MTB-pipeline (University-Cancer-Center-Schleswig-Holstein, UCCSH) to annotate a comprehensive dataset within the scope of a virtual MTB-setting, ultimately recommending molecularly stratified therapies. Evidence-levels for MTB-recommendations were defined in accordance with the NCT/DKTK and ESCAT criteria.

Results

Median age in the cohort was 76.5 years (range 56-91), 78.6% of patients were male, 50% were HIV-positive and clinical outcome was dismal. Comprehensive genomic/transcriptomic analysis revealed potential recommendations of a molecularly stratified treatment option with evidence-levels according to NCT/DKTK of at least m2B/ESCAT of at least IIIA were detected for all 14 prPBL-cases. In addition, immunohistochemical-assessment (CD19/CD30/CD38/CD79B) revealed targeted treatment-recommendations in all 14 cases. Genetic alterations were classified by treatment-baskets proposed by Horak et al. Hereby, we identified tyrosine-kinases (TK; n=4), PI3K-MTOR-AKT-pathway (PAM; n=3), cell-cycle-alterations (CC; n=2), RAF-MEK-ERK-cascade (RME; n=2), immune-evasion (IE; n=2), B-cell-targets (BCT; n=25) and others (OTH; n=4) for targeted treatment-recommendations. The minimum requirement for consideration of a drug within the scope of the study was FDA-fast-track development.

Discussion

The presented proof-of-concept study demonstrates the clinical potential of precision-oncology, even in prPBL-patients. Due to the aggressive course of the disease, there is an urgent medical-need for personalized treatment approaches, and this population should be considered for MTB inclusion at the earliest time.

Clinical implications of circulating tumor DNA in predicting the outcome of diffuse large B cell lymphoma patients receiving first-line therapy

BACKGROUND

Circulating tumor DNA (ctDNA) has been proven to be a promising tumor-specific biomarker in solid tumors, but its clinical utility in risk stratification and early prediction of relapse for diffuse large B cell lymphoma (DLBCL) has not been well explored.

METHODS

Here, using a lymphoma-specific sequencing panel, we assessed the prognostic and predictive utilities of ctDNA measurements before, during, and after first-line therapy in 73 Chinese DLBCL patients.

RESULTS

The pretreatment ctDNA level serving as an independent prognostic factor for both progression-free survival (PFS, adjusted HR 2.47; p = 0.004) and overall survival (OS, adjusted HR 2.49; p = 0.011) was confirmed in our cohort. Furthermore, the patients classified as molecular responders who presented a larger decrease in ctDNA levels after the initial two treatment cycles had more favorable PFS (unreached vs. 6.25 months; HR 5.348; p = 0.0015) and OS (unreached vs. 25.87; HR 4.0; p = 0.028) than non-responders. In addition, interim ctDNA clearance may be an alternative noninvasive method of positron emission tomography and computed tomography (PET-CT) for predicting better PFS (HR 3.65; p = 0.0033) and OS (HR 3.536; p = 0.016). We also demonstrated that posttreatment ctDNA was a sensitive indicator for detecting minimal residual disease (MRD) in patients with a high risk of recurrence (HR 6.471; p = 0.014), who were otherwise claimed to achieve radiographic CR (complete remission).

CONCLUSIONS

CtDNA is a promising noninvasive tool for prognosis prediction, response assessment, and early relapse prediction of first-line treatment in DLBCL patients.