Prognostic value of end-of-induction PET response after first-line immunochemotherapy for follicular lymphoma (GALLIUM): secondary analysis of a randomised, phase 3 trial

Advances in Treatment of Follicular Lymphoma

Follicular lymphoma (FL) is a heterogeneous disease with varying prognosis owing to differences in clinical, laboratory, and disease parameters. Although generally considered incurable, prognosis for early and advanced stage disease has improved because of therapeutic advances, several of which have resulted from elucidation of the biologic and molecular basis of the disease. The choice of treatment for FL is highly dependent on patient and disease characteristics. Several tools are available for risk stratification, although limitations in their routine clinical use exist. For limited disease, treatment options include radiotherapy, rituximab monotherapy or combination regimens, and surveillance. Treatment of advanced disease is often determined by tumor burden, with surveillance or rituximab considered for low tumor burden and chemoimmunotherapy for high tumor burden disease. Treatment for relapsed or refractory disease is influenced by initial first-line therapy and the duration and quality of the response. At present, there is no consensus for treatment of patients with early or multiply-relapsed disease; however, numerous agents, combination regimens, and transplant options have demonstrated efficacy. While the number of therapies available to treat FL has increased together with an improved understanding of the underlying biologic basis of disease, the best approach to select the most appropriate treatment strategy for an individual patient at a particular time continues to be elucidated. This chapter considers prognostic factors and the evolving treatment landscape of FL, including recent and emerging therapies, as well as remaining unmet needs.

Low absolute lymphocyte count is a poor prognostic factor for untreated advanced follicular lymphoma treated with rituximab plus bendamustine: results of the prospective phase 2 CONVERT trial

The aim of this trial is to evaluate the utility of rituximab-bendamustine (R-B) for untreated advanced follicular lymphoma (FL) showing non-optimal response (nOR) to R-CHOP, and to identify clinical prognostic factors for FL patients receiving R-B. Patients who failed to achieve complete response/complete response unconfirmed (CR/CRu) [nOR-group] after 2 cycles of R-CHOP subsequently received 6 cycles of R-B. The primary endpoint was the 3-year progression-free survival (PFS) rate. Secondary endpoints included determination of prognostic factors. Fifty-six patients initially received R-CHOP, 43/56 patients (76.8%) were judged as nOR, and 33/43 patients (76.7%) completed 6 cycles of R-B. At a median follow-up of 50.6 months in the nOR-group, the 3-year PFS rate was 69.0%, and the 3-year overall survival (OS) rate was 92.7%. The most common toxicities associated with R-B were grade 3-4 lymphopenia (93.0%) and neutropenia (74.4%), both of which were manageable. A multivariate analysis including dose intensity, serum soluble interleukin-2 receptor, and FL international prognostic index-2 revealed low absolute lymphocyte count (<  869/μL) at diagnosis was an independent poor prognostic factor for both PFS and OS in the R-B-treated nOR-group. This result was further confirmed in validation cohorts including R-B-treated de novo (n = 40) and relapsed (n = 49) FL patients.

Obinutuzumab in Combination with Chemotherapy Enhances Direct Cell Death in CD20-Positive Obinutuzumab-resistant Non-Hodgkin Lymphoma Cells

Follicular lymphoma commonly recurs and is difficult to cure. Obinutuzumab is a humanized glycoengineered type II anti-CD20 antibody with a mode of action that includes induction of antibody-dependent cellular cytotoxicity, antibody-dependent cellular phagocytosis, and direct cell death. There is no evidence on the effectiveness of retreatment with obinutuzumab in patients with prior obinutuzumab treatment. Using obinutuzumab-induced direct-cell-death-resistant cells, we investigated the efficacy of obinutuzumab retreatment in combination with chemotherapeutic agents used in follicular lymphoma treatment. Human non-Hodgkin lymphoma SU-DHL-4 cells were sustainably exposed to obinutuzumab in vitro, and 17 resistant clones expressing CD20 and showing 100-fold higher IC₅₀ of obinutuzumab than parental cells were established. The growth inhibition effect of obinutuzumab in combination with bendamustine, 4-hydroperoxy-cyclophosphamide, doxorubicin, vincristine, or prednisolone was estimated using an interaction index based on the Bliss independence model. For each clone, there were various combinations of obinutuzumab and chemotherapeutic agents that showed supra-additive effects. Obinutuzumab combined with doxorubicin enhanced caspase-dependent apoptosis and growth inhibition effect. Obinutuzumab combined with prednisolone enhanced DNA fragmentation and G₀-G₁ arrest. These combinations also had an antitumor effect in mouse xenograft models. Our results indicate that retreatment with obinutuzumab, when it is combined with chemotherapeutic agents, is effective in the CD20-positive obinutuzumab-induced direct-cell-death-resistant cells.

Novel Therapy Approaches to Follicular Lymphoma

Follicular lymphoma (FL) is the most common form of indolent non-Hodgkin lymphoma. It is a disease characterised by a long median overall survival and high response rates to currently available chemotherapy and anti-CD20 monoclonal antibody therapy combinations. However, for a sub-group of patients the disease behaves aggressively, fails to respond adequately to initial therapy or relapses early. For others, the disease becomes resistant following multiple lines of therapy, and despite recent advances the main cause of death for patients with FL remains their lymphoma. A wide landscape of novel therapies is emerging and the role of individual agents in the FL treatment paradigm is still being established. Some agents, including the cereblon modulator lenalidomide, the phosphatidylinositol 3-kinase inhibitors idelalisib, copanlisib and duvelisib, and the EZH2 inhibitor tazemetostat have received regulatory approval in the USA or European Union and have entered clinical practice for relapsed FL. Other developments, such as the emergence of immunotherapies including CAR-T cell therapy and bispecific antibodies, are expected to fundamentally change the approach to FL treatment in the future.

How we treat mature B-cell neoplasms (indolent B-cell lymphomas)

Mature B cell neoplasms, previously indolent non-Hodgkin lymphomas (iNHLs), are a heterogeneous group of malignancies sharing similar disease courses and treatment paradigms. Most patients with iNHL have an excellent prognosis, and in many, treatment can be deferred for years. However, some patients will have an accelerated course and may experience transformation into aggressive lymphomas. In this review, we focus on management concepts shared across iNHLs, as well as histology-specific strategies. We address open questions in the field, including the influence of genomics and molecular pathway alterations on treatment decisions. In addition, we review the management of uncommon clinical entities including nodular lymphocyte-predominant Hodgkin lymphoma, hairy cell leukemia, splenic lymphoma and primary lymphoma of extranodal sites. Finally, we include a perspective on novel targeted therapies, antibodies, antibody-drug conjugates, bispecific T cell engagers and chimeric antigen receptor T cell therapy.

Baseline SUVmax is related to tumor cell proliferation and patient outcome in follicular lymphoma

Follicular lymphoma (FL) is the most common indolent lymphoma. Despite the clear benefit of CD20-based therapy, a subset of FL patients still progress to aggressive lymphoma. Thus, identifying early biomarkers that incorporate PET metrics could be helpful to identify patients with a high risk of treatment failure with Rituximab. We retrospectively included a total of 132 untreated FL patients separated into training and validation cohorts. Optimal threshold of baseline SUVmax was first determined in the training cohort (n=48) to predict progression-free survival (PFS). The PET results were investigated along with the tumor and immune microenvironment, which were determined by immunochemistry and transcriptome studies involving gene set enrichment analyses and immune cell deconvolution, together with the tumor mutation profile. We report that baseline SUVmax >14.5 was associated with poorer PFS than baseline SUVmax ≤14.5 (HR=0.28; p=0.00046). Neither immune T-cell infiltration nor immune checkpoint expression were associated with baseline PET metrics. By contrast, FL samples with Ki-67 staining ≥10% showed enrichment of cell cycle/DNA genes (p=0.013) and significantly higher SUVmax values (p=0.007). Despite similar oncogenic pathway alterations in both SUVmax groups of FL samples, 4 out of 5 cases harboring the infrequent FOXO1 transcription factor mutation were seen in FL patients with SUVmax >14.5. Thus, high baseline SUVmax reflects FL tumor proliferation and, together with Ki-67 proliferative index, can be used to identify patients at risk of early relapse with R-chemotherapy.

Clinical and Biological Prognostic Factors in Follicular Lymphoma

Follicular lymphoma comprises approximately 20-30% of all cases of B-cell lymphomas. Median survival has improved significantly in the modern era. Prognostic factors include histologic grade, cytogenetics, molecular mutations, the tumor microenvironment, and tumor burden. Clinical prognostic indices are available and increasingly incorporate genetic information. Prognostic factors also arise during the course of treatment. Early progression within 24 months of initial chemoimmunotherapy is an adverse prognostic marker of inferior survival. Other high-risk populations include those with double refractory disease or those with high risk of transformation to diffuse large B-cell lymphoma.

Antibody Therapy Maintenance in Follicular Lymphoma

Because patients with follicular lymphoma (FL) usually experience repeated disease recurrences, maintenance treatment is an attractive option to prolong remission after induction therapy. Rituximab maintenance therapy has been shown in multiple randomized studies to significantly improve progression-free survival in FL with both low and high tumor burden after induction therapy, independently of patient and disease characteristics. Several questions regarding the use of antibody directed against CD20 (anti-CD20) maintenance remain open, including the optimal antibody administration schedule and duration, the risk/benefit ratio of maintenance in the context of previous bendamustine administration, and its cost-effectiveness.

Pretreatment SUVmax may influence the clinical benefit of BR over R-CHOP in patients with previously untreated FL

In 2 randomized phase 3 trials BR resulted in longer progression-free survival (PFS) than frontline R-CHOP in patients with indolent and mantle cell lymphoma. However, in subset analyses of follicular lymphoma (FL), the results were incongruent. We conducted a retrospective matched-pair analysis to compare the outcome of patients with advanced stage FL, receiving frontline BR (N = 73) or R-CHOP (N = 73), matched by age, gender, stage, and FL International Prognostic Index score. On multivariable analysis, baseline maximum standardized uptake value (SUV_max) >13 was associated with use of R-CHOP (p = .001). After a median follow-up of 69 months for the BR arm and 126 months for the R-CHOP arm, 5-year PFS was 80% and 70%, respectively (p = .07). After adjusting for SUV_max >13, the trend for better PFS in BR was not maintained. Prospective studies are needed to validate the role of pretreatment SUV_max as a stratification factor in future randomized therapeutic trials in FL.

The UK NCRI study of chlorambucil, mitoxantrone and dexamethasone (CMD) versus fludarabine, mitoxantrone and dexamethasone (FMD) for untreated advanced stage follicular lymphoma: molecular response strongly predicts prolonged overall survival

We present a long-term follow-up of the UK chlorambucil, mitoxantrone and dexamethasone (CMD) versus fludarabine, mitoxantrone and dexamethasone (FMD) for untreated advanced, symptomatic follicular lymphoma (FL). This trial was the first to prospectively assess molecular response and the impact on outcomes for 400 patients. The median progression-free survival (PFS) and overall survival (OS) for CMD were 3·6 and 14·6 years vs. 3·0 and 15·7 years for FMD, respectively. Estimates for Restricted Mean Survival Time (RMST) suggested no difference in PFS or OS. For the whole cohort there was a highly significant difference in survival by POD24, with a median OS from a risk-defining event of 3·9 years compared to 13·7 years for all others (RMST P < 0·001). Molecular remission was achieved in 25/46 patients (54·3%) in the CMD arm and 20/41 (48·8%) in the FMD arm (P = 0·6). Molecular negativity resulted in median PFS of 5·6 years vs. 2·3 years for molecularly positive (log-rank P < 0·001) and median OS not reached versus 12·5 years (log-rank P < 0·01). No cases of progression occurred in minimal residual disease (MRD) negative patients after six years of follow-up. Although there was no difference in outcomes between arms, this is the first prospective study to report MRD negativity resulting in significantly improved OS.

Positron-emission tomography-based staging reduces the prognostic impact of early disease progression in patients with follicular lymphoma

BACKGROUND

Previous studies reported that early progression of disease (POD) after initial therapy predicted poor overall survival (OS) in patients with follicular lymphoma (FL). Here, we investigated whether pre-treatment imaging modality had an impact on prognostic significance of POD.

METHODS

In this retrospective study, we identified 1088 patients with grade I-IIIA FL; of whom, 238 patients with stage II-IV disease were initially treated with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP), and 346 patients were treated with rituximab-based chemotherapy. Patients (N = 484) from the FOLL05 study served as an independent validation cohort. We risk-stratified patients based on pre-treatment radiographic imaging (positron-emission tomography [PET] versus computed tomography [CT]) and early POD status using event-defining and landmark analyses. A competing risk analysis evaluated the association between early POD and histologic transformation.

RESULTS

In the discovery cohort, patients with POD within 24 months (PFS24) of initiating R-CHOP therapy had a 5-year OS of 57.6% for CT-staged patients compared with 70.6% for PET-staged patients. In the validation cohort, the 5-year OS for patients with early POD was 53.9% and 100% in CT- and PET-staged patients, respectively. The risk of histologic transformation in patients whose disease progressed within one year of initiating therapy was higher in CT-staged patients than in PET-staged patients (16.7% versus 6.3%, respectively), which was associated with a 9.7-fold higher risk of death.

CONCLUSION

In FL, pre-treatment PET staging reduced the prognostic impact of early POD compared with CT staging. Patients with early POD and no histologic transformation have an extended OS with standard therapy.

Front-line management of non-Hodgkin lymphoma in Australia. Part 1: follicular lymphoma

Outcomes with follicular lymphoma (FL) have improved in the modern era and median survival is now beyond 15 years. Therapeutic decisions need to consider this increased survival as well as recent clinical trial data and emerging treatments. In this context, we present here current approaches to front-line management of FL in Australia. Treatment choices depend on the disease stage, tumour burden, the patient's age, symptoms, comorbidities and preferences. Only about 10-15% of patients with FL are diagnosed with early stage disease. For patients with low-grade, early stage disease, radiotherapy (RT) is recommended. The addition of chemotherapy has been shown to increase progression-free survival (PFS) but without demonstrated overall survival advantage. For patients with low-tumour-burden, advanced-stage FL, immediate treatment may not be required and we recommend considering active monitoring. For stage III/IV disease that is symptomatic and/or with high tumour burden, established first-line treatment is chemotherapy in combination with rituximab, often followed by rituximab maintenance. The listing of bendamustine and now obinutuzumab on the Pharmaceutical Benefits Scheme has expanded the first-line treatment options in Australia to include bendamustine in combination with rituximab (without rituximab maintenance permitted) or with obinutuzumab plus 2 years obintuzumab maintenance. In the FL subgroup of the Study group indolent Lymphomas (StiL) trial, therapy with bendamustine plus rituximab significantly increased PFS compared with rituximab in combination with cyclophosphamide, doxorubicin, vincristine and prednisolone, without rituximab maintenance. Initial tolerability may be more favourable with bendamustine in combination with anti-CD20 antibody therapy than other therapies overall, but clinical vigilance is still required because of concerns of late infectious toxicities associated with prolonged T-cell depletion.

Follicular lymphoma

Follicular lymphoma (FL) is a systemic neoplasm of the lymphoid tissue displaying germinal centre (GC) B cell differentiation. FL represents ~5% of all haematological neoplasms and ~20-25% of all new non-Hodgkin lymphoma diagnoses in western countries. Tumorigenesis starts in precursor B cells and becomes full-blown tumour when the cells reach the GC maturation step. FL is preceded by an asymptomatic preclinical phase in which premalignant B cells carrying a t(14;18) chromosomal translocation accumulate additional genetic alterations, although not all of these cells progress to the tumour phase. FL is an indolent lymphoma with largely favourable outcomes, although a fraction of patients is at risk of disease progression and adverse outcomes. Outcomes for FL in the rituximab era are encouraging, with ~80% of patients having an overall survival of >10 years. Patients with relapsed FL have a wide range of treatment options, including several chemoimmunotherapy regimens, phosphoinositide 3-kinase inhibitors, and lenalidomide plus rituximab. Promising new treatment approaches include epigenetic therapeutics and immune approaches such as chimeric antigen receptor T cell therapy. The identification of patients at high risk who require alternative therapies to the current standard of care is a growing need that will help direct clinical trial research. This Primer discusses the epidemiology of FL, its molecular and cellular pathogenesis and its diagnosis, classification and treatment.

Follicular Lymphoma: Recent and Emerging Therapies, Treatment Strategies, and Remaining Unmet Needs

Follicular lymphoma (FL) is a heterogeneous disease with varying prognosis owing to differences in clinical, laboratory, and disease parameters. Although generally considered incurable, prognosis for early- and advanced-stage disease has improved because of therapeutic advances, several of which have resulted from elucidation of the biologic and molecular basis of the disease. The choice of treatment for FL is highly dependent on patient and disease characteristics. Several tools are available for risk stratification, although limitations in their routine clinical use exist. For limited disease, treatment options include radiotherapy, rituximab monotherapy or combination regimens, and surveillance. Treatment of advanced disease is often determined by tumor burden, with surveillance or rituximab considered for low tumor burden and chemoimmunotherapy for high tumor burden disease. Treatment for relapsed or refractory disease is influenced by initial first-line therapy and the duration and quality of the response. Presently, there is no consensus for treatment of patients with early or multiply relapsed disease; however, numerous agents, combination regimens, and transplant options have demonstrated efficacy. Although the number of therapies available to treat FL has increased together with an improved understanding of the underlying biologic basis of disease, the best approach to select the most appropriate treatment strategy for an individual patient at a particular time continues to be elucidated. This review considers prognostication and the evolving treatment landscape of FL, including recent and emergent therapies as well as remaining unmet needs. IMPLICATIONS FOR PRACTICE: In follicular lymphoma, a personalized approach to management based on disease biology, patient characteristics, and other factors continues to emerge. However, application of current management requires an understanding of the available therapeutic options for first-line treatment and knowledge of current development in therapies for previously untreated and for relapsed or refractory disease. Thus, this work reviews for clinicians the contemporary data in follicular lymphoma, from advances in characterizing disease biology to current treatments and emerging novel therapies.

The role of obinutuzumab in the management of follicular lymphoma

The outcomes for follicular lymphoma (FL) have improved significantly in recent years. This has been driven by an improved understanding of the pathobiology of FL and the development of therapeutic anti-CD20 antibodies. Combining rituximab with chemotherapy, coupled with its use as maintenance therapy, has contributed to significant improvements in disease control and progression-free survival. However, FL remains incurable and almost all patients invariably relapse. Therefore, there remains a need to develop novel therapeutic options and optimize existing regimens. Obinutuzumab (a first-in-class, glycoengineered, humanized type 2 anti-CD20 antibody) has been evaluated in a number of clinical trials. In this review, we will summarize the evaluable results of clinical trials investigating the efficacy of obinutuzumab in the treatment of FL.

Pre-treatment maximum standardized uptake value predicts outcome after frontline therapy in patients with advanced stage follicular lymphoma

The impact of pre-treatment maximum standardized uptake value (SUV_max) on the outcome of follicular lymphoma (FL) following specific frontline regimens has not been explored. We performed a retrospective analysis of 346 patients with advanced stage follicular lymphoma (FL) without histological evidence of transformation, and analyzed the impact of SUV_max on outcome after frontline therapy. Fifty-two (15%) patients had a SUV_max >18, and a large lymph node ≥6 cm was the only factor associating with SUV_max >18 on multivariate analysis (odds ratio 2.7, 95% confidence interval [CI]: 1.3-5.3, P=0.006). The complete response rate was significantly lower among patients treated with non-anthracycline-based regimens if SUV_max was >18 (45% vs. 92%, P<0.001), but not among patients treated with R-CHOP (P=1). SUV_max >18 was associated with significantly shorter progression-free survival among patients treated with non-anthracycline-based regimens (77 months vs. not reached, P=0.02), but not among patients treated with R-CHOP (P=0.73). SUV_max >18 associated with shorter overall survival (OS) both in patients treated with R-CHOP (8-year OS 70% vs. 90%, P=0.02) and non-anthracycline-based frontline regimens (8-year OS 50% vs. 85%, P=0.001). In conclusion, pre-treatment PET scan has prognostic and predictive value in patients with advanced stage FL receiving frontline treatment.

Progression of Disease Within 24 Months in Follicular Lymphoma Is Associated With Reduced Intratumoral Immune Infiltration

PURPOSE

Understanding the immunobiology of the 15% to 30% of patients with follicular lymphoma (FL) who experience progression of disease within 24 months (POD24) remains a priority. Solid tumors with low levels of intratumoral immune infiltration have inferior outcomes. It is unknown whether a similar relationship exists between POD24 in FL.

PATIENTS AND METHODS

Digital gene expression using a custom code set—five immune effector, six immune checkpoint, one macrophage molecules—was applied to a discovery cohort of patients with early- and advanced-stage FL (n = 132). T-cell receptor repertoire analysis, flow cytometry, multispectral immunofluorescence, and next-generation sequencing were performed. The immune infiltration profile was validated in two independent cohorts of patients with advanced-stage FL requiring systemic treatment (n = 138, rituximab plus cyclophosphamide, vincristine, prednisone; n = 45, rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone), with the latter selected to permit comparison of patients experiencing a POD24 event with those having no progression at 5 years or more.

RESULTS

Immune molecules showed distinct clustering, characterized by either high or low expression regardless of categorization as an immune effector, immune checkpoint, or macrophage molecule. Low programmed death-ligand 2 (PD-L2) was the most sensitive/specific marker to segregate patients with adverse outcomes; therefore, PD-L2 expression was chosen to distinguish immune infiltration^HI (ie, high PD-L2) FL biopsies from immune infiltration^LO (ie, low PD-L2) tumors. Immune infiltration^HI tissues were highly infiltrated with macrophages and expanded populations of T-cell clones. Of note, the immune infiltration^LO subset of patients with FL was enriched for POD24 events (odds ratio [OR], 4.32; c-statistic, 0.81; P = .001), validated in the independent cohorts (rituximab plus cyclophosphamide, vincristine, prednisone: OR, 2.95; c-statistic, 0.75; P = .011; and rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone: OR, 7.09; c-statistic, 0.88; P = .011). Mutations were equally proportioned across tissues, which indicated that degree of immune infiltration is capturing aspects of FL biology distinct from its mutational profile.

CONCLUSION

Assessment of immune-infiltration by PD-L2 expression is a promising tool with which to help identify patients who are at risk for POD24.

Prognostic values of baseline, interim and end-of therapy 18F-FDG PET/CT in patients with follicular lymphoma

Purpose

In the present study, we aimed to investigate the role of baseline, interim and end-of treatment positron emission tomography/computed tomography (PET/CT) in assessing the prognosis of follicular lymphoma (FL).

Methods

A total of 84 FL patients were retrospectively analyzed in this study. Baseline (n=59), interim (n=24, after 2–4 cycles) and end-of treatment (n=43) PET/CT images were re-evaluated, and baseline maximum standardized uptake value (SUV_max), total metabolic tumor volume (tMTV) and total lesion glycolysis (TLG) were recorded. Interim (I-PET) and end-of treatment (E-PET) PET/CT responses were interpreted by Deauville five-point scale (D-5PS) and International Harmonization Project criteria (IHP). Survival curves were calculated by Kaplan-Meier curves, and differences between groups were compared by log-rank test.

Results

The 2-year progression-free survival (PFS) of the high- and low-TLG groups was 57.14% and 95.56%, respectively (p=0.0001). The 2-year overall survival (OS) of the high- and low-TLG groups was 62.50% and 100%, respectively (p<0.0001). Multivariate analysis showed that TLG was an independent prognostic factor for PFS (p=0.001, HR=6.577, 95% CI=2.167–19.960) and OS (p=0.030, HR=19.291, 95% CI =2.689–137.947). Besides, Eastern Cooperative Oncology Group (ECOG) was the independent prognostic factor for OS (HR=8.924, 95% CI=1.273–62.559, p=0.028). Interim PET results based on D-5PS or IHP criteria were not significantly correlated with PFS (all p>0.05). However, E-PET results using D-5PS and IHP criteria were statistically significant (p=0.0001 and p=0.006). The D-5PS showed stronger prognostic value compared with IHP criteria. The optimal cutoff value of ΔSUV_max% was 66.95% according to I-PET and 68.97% according to E-PET. However, only the ΔSUV_max% from the baseline to the end-of therapy yielded statistically significant results in the prediction of PFS (p=0.0002).

Conclusion

Our findings indicated that the baseline TLG and E-PET results were significantly associated with prognosis in patients with FL.

Diagnosis and management of follicular lymphoma: A comprehensive review

Follicular Lymphoma (FL) is an indolent lymphoma and may have various clinical courses. Worldwide, FL is the second most common non-Hodgkin lymphoma (NHL) type after diffuse large B-cell lymphoma. In this review article, the author is discussing relevant diagnostic tools, prognostic factors, and updated study results on the management of patients with newly diagnosed and relapsed/refractory FL. Controversies in the treatment, maintenance therapy, stem cell transplantation, and novel treatment approaches will be comprehensively discussed.

Detection of extranodal and spleen involvement by FDG-PET imaging predicts adverse survival in untreated follicular lymphoma

Predicting early clinical failure in patients with untreated follicular lymphoma (FL) is important but difficult. This study aimed to determine the incidence and patterns of extranodal (EN) and spleen disease using PET/CT, and assess their utility in predicting early clinical failure. PET/CT images from 613 cases of untreated FL (2003-2016) were reviewed. The location and number of EN sites, patterns of bone involvement, and splenic involvement were recorded. Outcomes were assessed using event-free survival (EFS), overall survival (OS), and early clinical failure at 24 months (EFS24). So, 49% (301/613) of patients had PET/CT-detected EN involvement, and 28% (171/613) had spleen involvement. The presence of ≥2 EN sites, spleen, bone or soft tissue involvement all predicted failure to achieve EFS24. Presence of ≥2 EN sites and bone involvement pattern were also predictive of OS in a univariate analysis. In a multivariate analysis with FLIPI-2 factors, spleen involvement, pattern of bone involvement, and soft tissue involvement independently predicted a lower EFS (HR 1.49 (1.11-2.00), P = .007; HR 1.71 (1.10-2.65), P = .017; and HR 1.67 (1.06-2.62), P = .026, respectively). When the multivariate analysis was performed using PRIMA-PI factors (marrow and B2M), the number of EN sites was an independent prognostic factor for inferior OS (HR 2.28; P = .05). Baseline PET/CT identifies EN involvement in nearly half of patients with untreated FL. The presence of ≥2 EN sites, bone, soft tissue, or splenic involvement predicts early clinical failure. These results, when combined with other factors, may better identify high-risk patients and guide therapy.

The role of PET/CT in the modern treatment of Hodgkin lymphoma

Classical Hodgkin Lymphoma is distinguished from other lymphomas by its peculiar biology and heterogeneous chemosensitivity. Most of the patients respond to the standard first-line treatment and are cured, however, in selected cases, the disease relapses or remains primarily refractory. Among predictive/prognostic factors ¹⁸FDG positron emission tomography (PET), fully integrated with computed tomography (PET/CT) proved to be extremely useful in identifying patients with poor prognosis at the time of diagnosis, during and at the end of treatment. The aim of this review is to present the current role of PET/CT in cHL at staging, interim and end of therapy assessment and its ability to guide treatment with a response- and risk-adapted strategy in clinical practice. Finally, quantitative PET measurement and the concurrent use of PET with selected biomarkers are discussed.

Management of patients with follicular lymphoma treated first line with obinutuzumab

Recently, obinutuzumab was included in the Australian Pharmaceutical Benefits Scheme for use in first line, advanced or bulky stage 2, follicular lymphoma, providing more immunochemotherapy treatment options available than ever before. Rituximab with chemotherapy has been the standard of care since reimbursement in the late 1990s; however, obinutuzumab-based regimens have shown superior progression-free survival in comparison to rituximab-based options, albeit at an increased risk of grade ≥3 adverse events. As median overall survival approaches 20 years or more, the long-term effects and sequencing of any strategy should be considered. Here we discuss the considerations for selection of front-line therapy, based on evidence and local Australian clinician experience, in the management of first line follicular lymphoma.

Time to Prepare for Risk Adaptation in Lymphoma by Standardizing Measurement of Metabolic Tumor Burden

Increased tumor burden is associated with inferior outcomes in many lymphoma subtypes. Surrogates of tumor burden that are easy to measure, such as the maximum tumor dimension of the bulkiest lesion on CT, have been used as prognostic indices for many years. Recently, total metabolic tumor volume (MTV) and tumor lesion glycolysis have emerged as promising and robust biomarkers of outcome in various lymphomas. The median MTV and the optimal cutoffs to separate patients into risk groups in a study population are, however, highly dependent on the population characteristics and the delineation method used to outline tumor on the PET image. This issue has precluded the use of MTV for risk stratification in trials and clinical practice. Standardization of the methodology is timely to allow the potential for risk adaptation to be explored in addition to response adaptation using PET. Meetings between representatives from research groups active in the field were held under the auspices of the PET International Lymphoma and Myeloma Workshop. A summary of those discussions, which included a review of the literature and a practical assessment of methods used for outlining, including various software options, is presented. Finally, a proposal is made to perform a technical validation of MTV measurement enabling benchmark reference ranges to be derived for published delineation approaches used for outlining with various software. This process would require collation of representative imaging data sets of the most common lymphoma subtypes; agreement on pragmatic criteria for the selection of lesions; generation of a range of MTVs, with consensus to be reached on final contours in a training set; and development of automated software solutions with a set of minimum functionalities to reduce measurement variability. Methods developed in the above training exercise could then be applied to another data set, with a final set of contours and values generated. This final data set would provide a benchmark against which end-users could test their ability to measure MTVs that are consistent with expected values. The data set and automated software solutions could be shared with manufacturers with the aim of including these in standard workflows to allow standardization of MTV measurement across the world.

Recent advances in the first-line treatment of follicular non-Hodgkin lymphoma

Follicular lymphoma (FL) is the most common type of indolent B-cell lymphoma. Twenty years ago, FL was considered an indolent lymphoma with a long survival time but without a high rate of complete remission with chemotherapies. The use of rituximab has improved the response and survival of patients with this lymphoma. More recently, development of biological knowledge and use of targeted drugs have offered new perspectives, including improvement of response rates and survival with chemo-free treatment strategies. In 2019, patients have a 10-year overall survival probability of over 70%. Histological transformation to more aggressive lymphoma and treatment relapses remain a medical challenge, especially for patients relapsing within two years. This article will review the recent advances in the treatment of FL. As the use of new drugs is directly related to the development of biological aspects, we will first summarize recent advances in biological aspects of FL.

One Size Does Not Fit All: Who Benefits From Maintenance After Frontline Therapy for Follicular Lymphoma?

Follicular lymphoma (FL) is the second most common non-Hodgkin lymphoma and the most common indolent B-cell malignancy. The disease often presents in advanced stage and can often be observed before initiation of therapy. Although the incidence is only approximately 15,000 new cases per year, the prevalence is substantially higher owing to the favorable overall survival (OS) of most patients. The most impactful advance responsible for the improvement of OS in FL was the introduction of the anti-CD20 monoclonal antibody (mAb) rituximab over 20 years ago. Phase III trials demonstrate that rituximab improves the OS in FL when combined with chemotherapy. However, unlike aggressive B-cell lymphomas, advanced stage FL is generally incurable and often displays a pattern of progressively shorter remissions with subsequent lines of therapy. Hence, maintenance strategies have been developed to prolong remissions achieved with frontline therapy. The value of maintenance after frontline therapy has been most extensively studied with extended treatment of anti-CD20 mAb, but recent approaches include chemotherapy-free combinations and targeted therapies given for extended durations. Here, we review relevant data that provide rationale in support of maintenance therapy in FL as well as the risks and limitations of a "one-size-fits-all" approach. Importantly, we note the biologic and clinical heterogeneity across patients with FL that must be considered when making clinical decisions. Finally, we highlight ongoing research that explores response-adapted approaches based on the depth of response as defined by PET scans and assays for minimal residual disease (MRD) that aim to better personalize individual management strategies.

Maintenance rituximab or observation after frontline treatment with bendamustine-rituximab for follicular lymphoma

Bendamustine (B) with rituximab (R) is a standard frontline treatment for medically fit follicular lymphoma (FL) patients. The safety and efficacy of maintenance rituximab (MR) after BR induction has not been formally compared to observation for FL, resulting in disparate practice patterns. Prospective trials have shown benefit of MR after R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) or R-CVP (rituximab, cyclophosphamide, vincristine, prednisone), yet recent data from the GALLIUM study comparing outcomes of patients treated with chemotherapy with R or obinutuzumab (G) showed higher than anticipated fatal adverse events with BR/BG. In order to assess the efficacy and tolerability of MR after BR, we retrospectively collected data on 640 newly diagnosed patients treated with FL. We found that patients who achieved partial remission (PR) after ≥4 cycles of BR had improved duration of response (DOR) with MR vs. no maintenance, whereas those in complete remission did not. These findings were confirmed in a validation cohort. In the entire study population, the known fatal adverse event rate after BR was 2·5% and did not significantly differ in those receiving MR versus no maintenance. [Correction added on 14 January 2019, after online publication: The preceding sentence has been corrected in this current version.] Within the limitations inherent to retrospective analysis, these data suggest that FL patients with a PR to BR experience prolongation of remission with MR with an acceptable safety profile.