Results of the randomized phase IIB ADMIRE trial of FCR with or without mitoxantrone in previously untreated CLL

Comparing the efficacy and safety of first-line treatments for chronic lymphocytic leukemia: a network meta-analysis

BACKGROUND

The chronic lymphocytic leukemia treatment strategies have transitioned from chemotherapy and chemoimmunotherapy to chemotherapy-free regimens. Frequentist network meta-analysis allows for direct and indirect comparisons between different treatments.

METHODS

Randomized controlled trials assessing first-line treatments were included. Outcomes were progression-free survival (PFS), overall survival, undetectable minimal residual disease, objective response rate, and adverse events. Studies with comparable characteristics also underwent subgroup analysis, stratifying by age, comorbidities, IGHV status, and cytogenetic abnormalities.

RESULTS

A total of 30 eligible trials involved 12 818 patients, and 30 treatments were included. Acalabrutinib demonstrated a PFS advantage over ibrutinib and obinutuzumab-venetoclax in patients aged older than 65 years or with unmutated IGHV. In younger patients with comorbidities, acalabrutinib-obinutuzumab had superior PFS compared with ibrutinib-obinutuzumab, ibrutinib-venetoclax, and obinutuzumab-venetoclax. For older patients with comorbidities, acalabrutinib and acalabrutinib-obinutuzumab outperformed obinutuzumab-venetoclax without statistically difference between them. Minimal residual disease-guided ibrutinib-venetoclax surpassed obinutuzumab-venetoclax in patients without comorbidities. Ibrutinib-obinutuzumab exhibited extended PFS benefits compared with obinutuzumab-venetoclax in patients with mutated IGHV or with del(17p) and/or TP53 mutations. Ibrutinib-venetoclax and ibrutinib-obinutuzumab had lower neutropenia rates than obinutuzumab-venetoclax. Ibrutinib-venetoclax had fewer infections than acalabrutinib and acalabrutinib-obinutuzumab. Acalabrutinib-obinutuzumab caused less diarrhea than ibrutinib-venetoclax but more headaches than ibrutinib-obinutuzumab and obinutuzumab-venetoclax. Obinutuzumab-venetoclax had lower hypertension rates than ibrutinib-obinutuzumab. Ibrutinib-venetoclax had fewer arthralgia than acalabrutinib-obinutuzumab. For any grade secondary primary neoplasms, ibrutinib-venetoclax and obinutuzumab-venetoclax was less than acalabrutinib-obinutuzumab.

CONCLUSION

Tailored chemotherapy-free regimens can be selected based on age, comorbidities, IGHV status, and cytogenetic abnormalities to optimize treatment outcomes while considering different adverse events spectra.

Ibrutinib and rituximab versus fludarabine, cyclophosphamide, and rituximab for patients with previously untreated chronic lymphocytic leukaemia (FLAIR): interim analysis of a multicentre, open-label, randomised, phase 3 trial

BACKGROUND

The approval of Bruton tyrosine kinase (BTK) inhibitors in patients with previously untreated chronic lymphocytic leukaemia (CLL) was based on trials which compared ibrutinib with alkylating agents in patients considered unfit for fludarabine, cyclophosphamide, and rituximab, the most effective chemoimmunotherapy in CLL. We aimed to assess whether ibrutinib and rituximab is superior to fludarabine, cyclophosphamide, and rituximab in terms of progression-free survival.

METHODS

This study is an interim analysis of FLAIR, which is an open-label, randomised, controlled, phase 3 trial in patients with previously untreated CLL done at 101 UK National Health Service hospitals. Eligible patients were between 18 and 75 years of age with a WHO performance status of 2 or less and disease status requiring treatment according to International Workshop on CLL criteria. Patients with greater than 20% of their CLL cells having the chromosome 17p deletion were excluded. Patients were randomly assigned (1:1) by means of minimisation (Binet stage, age, sex, and centre) with a random element in a web-based system to ibrutinib and rituximab (ibrutinib administered orally at 420 mg/day for up to 6 years; rituximab administered intravenously at 375 mg/m2 on day 1 of cycle 1 and at 500 mg/m2 on day 1 of cycles 2-6 of a 28-day cycle) or fludarabine, cyclophosphamide, and rituximab (fludarabine 24 mg/m2 per day orally on day 1-5, cyclophosphamide 150 mg/m2 per day orally on days 1-5; rituximab as above for up to 6 cycles). The primary endpoint was progression-free survival, analysed by intention to treat. Safety analysis was per protocol. This study is registered with ISRCTN, ISRCTN01844152, and EudraCT, 2013-001944-76, and recruiting is complete.

FINDINGS

Between Sept 19, 2014, and July 19, 2018, of 1924 patients assessed for eligibility, 771 were randomly assigned with median age 62 years (IQR 56-67), 565 (73%) were male, 206 (27%) were female and 507 (66%) had a WHO performance status of 0. 385 patients were assigned to fludarabine, cyclophosphamide, and rituximab and 386 patients to ibrutinib and rituximab. After a median follow-up of 53 months (IQR 41-61) and at prespecified interim analysis, median progression-free survival was not reached (NR) with ibrutinib and rituximab and was 67 months (95% CI 63-NR) with fludarabine, cyclophosphamide, and rituximab (hazard ratio 0·44 [95% CI 0·32-0·60]; p<0·0001). The most common grade 3 or 4 adverse event was leukopenia (203 [54%] patients in the fludarabine, cyclophosphamide, and rituximab group and 55 [14%] patients in the ibrutinib and rituximab group. Serious adverse events were reported in 205 (53%) of 384 patients receiving ibrutinib and rituximab compared with 203 (54%) of 378 patients receiving fludarabine, cyclophosphamide, and rituximab. Two deaths in the fludarabine, cyclophosphamide, and rituximab group and three deaths in the ibrutinib and rituximab group were deemed to be probably related to treatment. There were eight sudden unexplained or cardiac deaths in the ibrutinib and rituximab group and two in the fludarabine, cyclophosphamide, and rituximab group.

INTERPRETATION

Front line treatment with ibrutinib and rituximab significantly improved progression-free survival compared with fludarabine, cyclophosphamide, and rituximab but did not improve overall survival. A small number of sudden unexplained or cardiac deaths in the ibrutinib and rituximab group were observed largely among patients with existing hypertension or history of cardiac disorder.

FUNDING

Cancer Research UK and Janssen.

A History of Targeted Therapy Development and Progress in Novel-Novel Combinations for Chronic Lymphocytic Leukemia (CLL)

Over the last 10 years, the traditional treatment paradigms for CLL have been upended as the use of traditional chemoimmunotherapy regimens has declined in favor of novel targeted therapies. Targeted therapies have become the new standard of care in CLL given their superior progression-free survival (and overall survival, in some cases) when compared with chemoimmunotherapy, as well as their improved toxicity profiles. Targeted agents are FDA approved for the treatment of CLL including ibrutinib, acalabrutinib, zanubrutinib, and venetoclax. Importantly, as opposed to traditional chemotherapy regimens, the benefits of these targeted therapies appear to be consistent regardless of high-risk mutational status. In this review, we discuss the pivotal CLL studies of the last decade and the data supporting doublet and triplet novel-novel combinations. We explore the use of new surrogate end points for PFS/OS in targeted therapies such as undetectable minimal residual disease (uMRD) and their potential role in minimizing toxicity by permitting earlier treatment discontinuation. We also highlight areas that warrant further exploration and future studies that may help address some of these key questions.

Obinutuzumab as consolidation after chemo-immunotherapy: Results of the UK National Cancer Research Institute phase II/III GALACTIC trial

The GA101 (obinutuzumab) monocLonal Antibody as Consolidation Therapy In chronic lymphocytic leukaemia (CLL) (GALACTIC) was a seamless phase II/III trial designed to test whether consolidation with obinutuzumab is safe and eradicates minimal residual disease (MRD) and, subsequently, whether this leads to prolonged progression-free survival (PFS) in patients with CLL who have recently responded to chemo-immunotherapy. Patients with a response 3-24 months after chemotherapy were assessed for MRD. MRD-positive patients were randomised to receive consolidation therapy with obinutuzumab or no consolidation. The trial closed after the phase II part due to slow recruitment. In all, 48 patients enrolled of whom 19 were MRD negative and were monitored. Of the 29 MRD-positive patients, 14 were randomised to receive consolidation and 15 to no consolidation. At 6 months after randomisation, 10 and 13 consolidated patients achieved MRD negativity by flow cytometry (sensitivity 10-4 ) in bone marrow and peripheral blood respectively. PFS was significantly better in consolidated patients compared to non-consolidated patients (p = 0.001). No difference was observed in PFS, overall survival or duration of MRD negativity when comparing the 10 MRD-negative patients after consolidation with the 19 MRD-negative patients in the monitoring group. Common adverse events in the consolidation arm were thrombocytopenia, infection, and cough. Only 1% of events were infusion-related reactions. This observation provides further evidence that consolidation to achieve MRD negativity improves outcomes in CLL and that obinutuzumab is well tolerated in patients with low levels of disease.

Whole-genome sequencing of chronic lymphocytic leukemia identifies subgroups with distinct biological and clinical features

The value of genome-wide over targeted driver analyses for predicting clinical outcomes of cancer patients is debated. Here, we report the whole-genome sequencing of 485 chronic lymphocytic leukemia patients enrolled in clinical trials as part of the United Kingdom's 100,000 Genomes Project. We identify an extended catalog of recurrent coding and noncoding genetic mutations that represents a source for future studies and provide the most complete high-resolution map of structural variants, copy number changes and global genome features including telomere length, mutational signatures and genomic complexity. We demonstrate the relationship of these features with clinical outcome and show that integration of 186 distinct recurrent genomic alterations defines five genomic subgroups that associate with response to therapy, refining conventional outcome prediction. While requiring independent validation, our findings highlight the potential of whole-genome sequencing to inform future risk stratification in chronic lymphocytic leukemia.

Secondary primary malignancies after treatment with chemo-immunotherapy in treatment-naïve patients with CLL: a systematic literature review

OBJECTIVES

In chronic lymphocytic leukemia (CLL), therapy-related cytotoxicity and the resulting immunodeficiency are thought to contribute to the development of secondary primary malignancies (SPM). Here we analyzed clinical trial data on the occurrence of SPM following chemo-immunotherapy (CIT) regimens in treatment-naïve CLL patients.

METHODS

A systematic literature search was conducted covering multiple databases between 2003-2019. Data from relevant clinical trials on the proportion of patients with SPMs were extracted. Then the number of SPM patients/person-years was calculated by taking into account the trials' follow-up time. Finally, a random-effects meta-analysis to pool the rates from individual studies was performed.

RESULTS

We identified 22 studies reporting SPM data available for analysis. Random-effects meta-analysis estimated that the number of SPM patients/1000 person-years was 24 (95%CI: 19-29). Results from trials with cancer-specific data indicated 19 (95%CI: 14-26) solid and 9 (95%CI: 6-12) hematological SPM patients/1000 person-years. These estimations did not change significantly when sub-groups were analysed by CIT regimens.

CONCLUSION

Although pooling data with the intention to analyze adverse event rates is challenging, our study concluded that in case of CIT regimens, SPM should be considered an important adverse outcome. Different regimens showed similar trends; however, other clinical and demographic factors have a profound impact in this respect.

Measurable residual disease in chronic lymphocytic leukemia: expert review and consensus recommendations

Assessment of measurable residual disease (often referred to as "minimal residual disease") has emerged as a highly sensitive indicator of disease burden during and at the end of treatment and has been correlated with time-to-event outcomes in chronic lymphocytic leukemia. Undetectable-measurable residual disease status at the end of treatment demonstrated independent prognostic significance in chronic lymphocytic leukemia, correlating with favorable progression-free and overall survival with chemoimmunotherapy. Given its utility in evaluating depth of response, determining measurable residual disease status is now a focus of outcomes in chronic lymphocytic leukemia clinical trials. Increased adoption of measurable residual disease assessment calls for standards for nomenclature and outcomes data reporting. In addition, many basic questions have not been systematically addressed. Here, we present the work of an international, multidisciplinary, 174-member panel convened to identify critical questions on key issues pertaining to measurable residual disease in chronic lymphocytic leukemia, review evaluable data, develop unified answers in conjunction with local expert input, and provide recommendations for future studies. Recommendations are presented regarding methodology for measurable residual disease determination, assay requirements and in which tissue to assess measurable residual disease, timing and frequency of assessment, use of measurable residual disease in clinical practice versus clinical trials, and the future usefulness of measurable residual disease assessment. Nomenclature is also proposed. Adoption of these recommendations will work toward standardizing data acquisition and interpretation in future studies with new treatments with the ultimate objective of improving outcomes and curing chronic lymphocytic leukemia.

Photobiomodulation therapy for the prevention of acute radiation dermatitis in breast cancer patients undergoing hypofractioned whole-breast irradiation (LABRA trial)

OBJECTIVES

To evaluate the efficacy of photobiomodulation therapy in breast cancer patients post-lumpectomy undergoing hypofractionated whole-breast irradiation (HF-WBI) for the prevention and management of acute radiodermatitis (ARD).

MATERIALS AND METHODS

A randomized, multicentric clinical trial (LABRA trial, NCT03924011) was set up at the Limburg Oncology Center, including the Jessa Hospital (Hasselt, BE) and Ziekenhuis Oost-Limburg (Genk, BE). A total of 71 breast cancer patients planned to undergo HF-WBI were randomized to one of the two study arms: the control group (n = 32) or the PBM group (n = 39). The PBM group received the standard institutional skincare combined with PBM (2×/week) during the complete radiotherapy (RT) course. Patients in the control group received the standard skincare combined with placebo treatment (2x/week). Patients' skin reactions were evaluated weekly during the RT treatment by using the modified version of the Radiation Therapy Oncology Group (RTOG) criteria.

RESULTS

At week 3 of RT, one patient presented a grade 2 and one patient a grade 3 skin reaction in the control group, while in the PBM group, all patients still presented grade 1 ARD. At the final RT session 28% of the patients presenting grade 2-3 ARD, while in the PBM group 10% presented grade 2 and no grade 3 ARD. PBM reduced the incidence of severe ARD by 18%. However, the difference was not significant (p = 0.053).

CONCLUSION

Based on the LABRA trial results, PBM seems not able to reduce the incidence of severe ARD in breast cancer patients undergoing HF-WBI. Research in a larger patient population is recommended.

TP53 Mutations with Low Variant Allele Frequency Predict Short Survival in Chronic Lymphocytic Leukemia

PURPOSE

In chronic lymphocytic leukemia (CLL), TP53 mutations are associated with reduced survival and resistance to standard chemoimmunotherapy (CIT). Nevertheless, the clinical impact of subclonal TP53 mutations below 10% to 15% variant allele frequency (VAF) remains unclear.

EXPERIMENTAL DESIGN

Using a training/validation approach, we retrospectively analyzed the clinical and biological features of TP53 mutations above (high-VAF) or below (low-VAF) the previously reported 10.0% VAF threshold, as determined by deep next-generation sequencing. Clinical impact of low-VAF TP53 mutations was also confirmed in a cohort (n = 251) of CLL treated with fludarabine-cyclophosphamide-rituximab (FCR) or FCR-like regimens from two UK trials.

RESULTS

In the training cohort, 97 of 684 patients bore 152 TP53 mutations, while in the validation cohort, 71 of 536 patients had 109 TP53 mutations. In both cohorts, patients with the TP53 mutation experienced significantly shorter overall survival (OS) than TP53 wild-type patients, regardless of the TP53 mutation VAF. By combining TP53 mutation and 17p13.1 deletion (del17p) data in the total cohort (n = 1,220), 113 cases were TP53 mutated only (73/113 with low-VAF mutations), 55 del17p/TP53 mutated (3/55 with low-VAF mutations), 20 del17p only, and 1,032 (84.6%) TP53 wild-type. A model including low-VAF cases outperformed the canonical model, which considered only high-VAF cases (c-indices 0.643 vs. 0.603, P < 0.0001), and improved the prognostic risk stratification of CLL International Prognostic Index. Clinical results were confirmed in CIT-treated cases (n = 552) from the retrospective cohort, and the UK trials cohort.

CONCLUSIONS

TP53 mutations affected OS regardless of VAF. This finding can be used to update the definition of TP53 mutated CLL for clinical purposes.

Skipping a step: what happened to the design of randomized clinical trials in chronic lymphocytic leukaemia?

Clinical research of chronic lymphocytic leukaemia (CLL) has been advancing at an unprecedented pace. Several randomized studies in the current era of oral targeted agents seem to have skipped one step and proceeded directly to combinations with antibodies, omitting the testing of novel-agent monotherapy. Thus, the ibrutinib + rituximab combination was used as the experimental arm in a major trial for untreated fit patients while two other trials subsequently showed that addition of rituximab to ibrutinib does not produce any meaningful benefit. Similarly, two large trials omitted venetoclax monotherapy and proceeded directly to venetoclax + rituximab or obinutuzumab versus chemoimmunotherapy. While such trials are undoubtedly cheaper, quicker and easier to manage, they leave the CLL community with uncertainty regarding the real role of the monoclonal antibody components. Thus, we are left with regimens which are undoubtedly effective, but might actually be unnecessarily toxic and expensive. The solution to this problem is simple: future randomized trials should be carefully designed in a 'step by step' fashion which would provide the CLL community with simple yet robust answers regarding efficacy of novel regimens so that these can be introduced to practice following the best principles of evidence-based medicine.

SAMHD1 Limits the Efficacy of Forodesine in Leukemia by Protecting Cells against the Cytotoxicity of dGTP

The anti-leukemia agent forodesine causes cytotoxic overload of intracellular deoxyguanosine triphosphate (dGTP) but is efficacious only in a subset of patients. We report that SAMHD1, a phosphohydrolase degrading deoxyribonucleoside triphosphate (dNTP), protects cells against the effects of dNTP imbalances. SAMHD1-deficient cells induce intrinsic apoptosis upon provision of deoxyribonucleosides, particularly deoxyguanosine (dG). Moreover, dG and forodesine act synergistically to kill cells lacking SAMHD1. Using mass cytometry, we find that these compounds kill SAMHD1-deficient malignant cells in patients with chronic lymphocytic leukemia (CLL). Normal cells and CLL cells from patients without SAMHD1 mutation are unaffected. We therefore propose to use forodesine as a precision medicine for leukemia, stratifying patients by SAMHD1 genotype or expression.

An Updated Perspective on Current Prognostic and Predictive Biomarkers in Chronic Lymphocytic Leukemia in the Context of Chemoimmunotherapy and Novel Targeted Therapy

Chronic lymphocytic leukemia (CLL) is a heterogeneous disease with a variable clinical course. Novel biomarkers discovered over the past 20 years have revolutionized the way clinicians approach prognostication and treatment especially in the chemotherapy-free era. Herein, we review the best established prognostic and predictive biomarkers in the setting of chemoimmunotherapy (CIT) and novel targeted therapy. We propose that TP53 disruption (defined as either TP53 mutation or chromosome 17p deletion), unmutated immunoglobulin heavy chain variable region gene status (UM IGHV), NOTCH1 mutation, and CD49d expression are the strongest prognosticators of disease progression and overall survival in the field of novel biomarkers including recurrent gene mutations. We also highlight the predictive role of TP53 disruption, UM IGHV, and NOTCH1 mutation in the setting of CIT and TP53 disruption and CD49d expression in the setting of novel targeted therapy employing B-cell receptor (BCR) and B-cell lymphoma-2 (BCL2) inhibition. Finally, we discuss future directions in the field of biomarker development to identify those with relapsed/refractory disease at risk for progression despite treatment with novel therapies.

IGHV mutational status and outcome for patients with chronic lymphocytic leukemia upon treatment: a Danish nationwide population-based study

Patients with chronic lymphocytic leukemia and unmutated immunoglobulin heavy-chain variable region gene (IGHV) have inferior survival from time of treatment in clinical studies. We assessed real-world outcomes based on mutational status and treatment regimen in a nationwide population-based cohort, comprising all 4,135 patients from the Danish chronic lymphocytic leukemia registry diagnosed between 2008 and 2017. In total, 850 patients with known mutational status received treatment: 42% of patients received intensive chemoimmunotherapy consisting of fludarabine, cyclophosphamide plus rituximab, or bendamustine plus rituximab; 27% received chlorambucil in combination with anti-CD20 antibodies or as monotherapy, and 31% received other, less common treatments. No difference in overall survival from time of first treatment according to mutational status was observed, while treatment-free survival from start of first treatment was inferior for patients with unmutated IGHV. The median treatment-free survival was 2.5 years for patients treated with chlorambucil plus anti-CD20, and 1 year for those who received chlorambucil monotherapy. The 3-year treatment-free survival rates for patients treated with fludarabine, cyclophosphamide plus rituximab, and bendamustine plus rituximab were 90% and 91% for those with mutated IGHV, and 76% and 53% for those with unmutated IGHV, respectively, and the 3-year overall survival rates were similar for the two regimens (86-88%). Thus, it appears that, in the real-world setting, patients progressing after intensive chemoimmunotherapy as first-line therapy can be rescued by subsequent treatment, without jeopardizing their long overall survival. Intensive chemoimmunotherapy remains a legitimate option alongside targeted agents, and part of a personalized treatment landscape in chronic lymphocytic leukemia, while improved supportive care and treatment options are warranted for unfit patients.

Clinical significance of DNA methylation in chronic lymphocytic leukemia patients: results from 3 UK clinical trials

Chronic lymphocytic leukemia patients with mutated immunoglobulin heavy-chain genes (IGHV-M), particularly those lacking poor-risk genomic lesions, often respond well to chemoimmunotherapy (CIT). DNA methylation profiling can subdivide early-stage patients into naive B-cell-like CLL (n-CLL), memory B-cell-like CLL (m-CLL), and intermediate CLL (i-CLL), with differing times to first treatment and overall survival. However, whether DNA methylation can identify patients destined to respond favorably to CIT has not been ascertained. We classified treatment-naive patients (n = 605) from 3 UK chemo and CIT clinical trials into the 3 epigenetic subgroups, using pyrosequencing and microarray analysis, and performed expansive survival analysis. The n-CLL, i-CLL, and m-CLL signatures were found in 80% (n = 245/305), 17% (53/305), and 2% (7/305) of IGHV-unmutated (IGHV-U) cases, respectively, and in 9%, (19/216), 50% (108/216), and 41% (89/216) of IGHV-M cases, respectively. Multivariate Cox proportional analysis identified m-CLL as an independent prognostic factor for overall survival (hazard ratio [HR], 0.46; 95% confidence interval [CI], 0.24-0.87; P = .018) in CLL4, and for progression-free survival (HR, 0.25; 95% CI, 0.10-0.57; P = .002) in ARCTIC and ADMIRE patients. The analysis of epigenetic subgroups in patients entered into 3 first-line UK CLL trials identifies m-CLL as an independent marker of prolonged survival and may aid in the identification of patients destined to demonstrate prolonged survival after CIT.

Telomere length predicts for outcome to FCR chemotherapy in CLL

We have previously shown that dividing patients with CLL into those with telomeres inside the fusogenic range (TL-IFR) and outside the fusogenic range (TL-OFR) is powerful prognostic tool. Here, we used a high-throughput version of the assay (HT-STELA) to establish whether telomere length could predict for outcome to fludarabine, cyclophosphamide, rituximab (FCR)-based treatment using samples collected from two concurrent phase II studies, ARCTIC and ADMIRE (n = 260). In univariate analysis, patients with TL-IFR had reduced progression-free survival (PFS) (P < 0.0001; HR = 2.17) and shorter overall survival (OS) (P = 0.0002; HR = 2.44). Bifurcation of the IGHV-mutated and unmutated subsets according to telomere length revealed that patients with TL-IFR in each subset had shorter PFS (HR = 4.35 and HR = 1.48, respectively) and shorter OS (HR = 3.81 and HR = 2.18, respectively). In addition, the OS of the TL-OFR and TL-IFR subsets were not significantly altered by IGHV mutation status (P = 0.61; HR = 1.24 and P = 0.41; HR = 1.47, respectively). In multivariate modeling, telomere length was the dominant co-variable for PFS (P = 0.0002; HR = 1.85) and OS (P = 0.05; HR = 1.61). Taken together, our data suggest that HT-STELA is a powerful predictor of outcome to FCR-based treatment and could be used to inform the design of future risk-adapted clinical trials.

Minimal Residual Disease Quantification in Chronic Lymphocytic Leukemia: Clinical Significance and Flow Cytometric Methods

The very sensitive quantification of leukemia cells that persist in chronic lymphocytic leukemia patients after successful therapy is steadily gaining interest with clinical scientists. Minimal residual disease (MRD) has demonstrated prognostic significance in the context of different treatment modalities leading to its approval as an intermediate endpoint for licensure in randomized trials by the European Medicine Agency. Data supporting the clinical impact of MRD as well as a highly standardized and broadly available method for MRD assessments by flow cytometry are described herein. Examples of gating strategies are provided with comprehensive explanations to allow the reader the application of the technology to blood and bone samples with high and very low level MRD, respectively. This chapter has a particular focus on samples acquired shortly after anti-CD20 treatment. The standardization developed by the EuroFlow consortium is additionally described as technical basis for reproducible and standardized flow cytometric MRD assessments.

Flow Cytometric MRD Detection in Selected Mature B-Cell Malignancies

The quantification of submicroscopic minimal residual disease (MRD) after therapy proved to have independent prognostic significance in many mature B-cell malignancies. With the advent of routine benchtop cytometers capable of simultaneously analyzing ≥4 colors and with improved standardization, flow cytometry has become the method of choice for MRD assessments in some lymphoma entities. Herein we describe general aspects of flow cytometric standardization. Chronic lymphocytic leukemia and multiple myeloma (MM) are used as examples to explain the technical standardization of flow cytometry for MRD detection according to EuroFlow strategies. MRD data acquisition and detailed analysis using a newly developed approach (so-called next generation flow, NGF) in MM is a particular focus of this chapter.

Optimal management of the young patient CLL patient

The emergence of targeted therapy for patients with chronic lymphocytic leukemia (CLL) has permanently altered the therapeutic landscape. In both upfront and relapsed settings, safe and effective oral kinase inhibitors are available which rival the responses and durability seen with standard chemo immunotherapy regimens. In 2016, ibrutinib was granted Federal Drug Administration approval for first-line therapy in patients with CLL. While its role as initial therapy for older, unfit or deleted 17p CLL patients is less controversial, its role as first-line treatment for younger fit patients is less clear, begging the question, what is the optimal treatment for these patients, novel agents or standard CIT strategies? In this review, we aim to provide guidance for what we believe is the optimal management of young fit patients with CLL.

FCR achieves long-term durable remissions in patients with IGHV-mutated CLL

In chronic lymphocytic leukemia (CLL) patients with mutated IGHV, 3 recent studies have demonstrated prolonged progression-free survival (PFS) after treatment with fludarabine-cyclophosphamide-rituximab (FCR) chemoimmunotherapy. We performed a systematic review to assess the benefit of FCR for patients with CLL and identified 5 randomized trials that met our inclusion criteria. FCR improved complete remission, PFS and overall survival vs the comparator; median PFS was not reached in the subgroup of CLL patients with mutated IGHV.

Results of the randomized phase IIB ARCTIC trial of low-dose rituximab in previously untreated CLL

ARCTIC was a multicenter, randomized-controlled, open, phase IIB non-inferiority trial in previously untreated chronic lymphocytic leukemia (CLL). Conventional frontline therapy in fit patients is fludarabine, cyclophosphamide and rituximab (FCR). The trial hypothesized that including mitoxantrone with low-dose rituximab (FCM-miniR) would be non-inferior to FCR. A total of 200 patients were recruited to assess the primary end point of complete remission (CR) rates according to IWCLL criteria. Secondary end points were progression-free survival (PFS), overall survival (OS), overall response rate, minimal residual disease (MRD) negativity, safety and cost-effectiveness. The trial closed following a pre-planned interim analysis. At final analysis, CR rates were 76 FCR vs 55% FCM-miniR (adjusted odds ratio: 0.37; 95% confidence interval: 0.19-0.73). MRD-negativity rates were 54 FCR vs 44% FCM-miniR. More participants experienced serious adverse reactions with FCM-miniR (49%) compared to FCR (41%). There are no significant differences between the treatment groups for PFS and OS. FCM-miniR is not expected to be cost-effective over a lifetime horizon. In summary, FCM-miniR is less well tolerated than FCR with an inferior response and MRD-negativity rate and increased toxicity, and will not be taken forward into a confirmatory trial. The trial demonstrated that oral FCR yields high response rates compared to historical series with intravenous chemotherapy.