Eradication of bone marrow minimal residual disease may prompt early treatment discontinuation in CLL

Measurable Residual Disease and Clinical Outcomes in Chronic Lymphocytic Leukemia: A Systematic Review and Meta-Analysis

Importance

Measurable residual disease (MRD) refers to the presence of disease at low levels not detected by conventional pathologic analysis. The association of MRD status as a surrogate end point of clinical outcome in chronic lymphocytic leukemia (CLL) has not been established in the era of targeted agents. Assessing the association of MRD with progression-free survival (PFS) may improve its role as a surrogate marker and allow its use to accelerate drug development.

Objective

To assess the association between MRD and PFS in CLL using data from prospective clinical trials that studied targeted agents or obinutuzumab-based treatment.

Data Sources

Clinical studies on CLL were identified via searches of PubMed, Embase, Scopus, and Web of Science from inception through July 31, 2023.

Study Selection

Prospective, single-arm, and randomized clinical trials that assessed targeted agents or obinutuzumab-based treatment and reported PFS by MRD status were included. Studies with insufficient description of MRD information were excluded.

Data Extraction and Synthesis

Study sample size, median patient age, median follow-up time, line of treatment, MRD detection method and time points, and survival outcomes were extracted.

Main Outcomes and Measures

Analyses of survival probabilities and hazard ratios (HRs) were conducted for PFS according to MRD status. Meta-analyses were performed using a random-effects model.

Results

A total of 11 prospective clinical trials (9 randomized and 2 nonrandomized) including 2765 patients were analyzed. Achieving undetectable MRD (uMRD) at 0.01% was associated with an HR of 0.28 (95% CI, 0.20-0.39; P < .001) for PFS. Median PFS was not reached in both groups (uMRD vs MRD), but the estimated 24-month PFS was better in the uMRD group (91.9% [95% CI, 88.8%-95.2%] vs 75.3% [95% CI, 64.7%-87.6%]; P < .001). The association of uMRD with PFS was observed in subgroup analyses in the first-line treatment setting (HR, 0.24; 95% CI, 0.18-0.33), relapsed or refractory disease setting (HR, 0.34; 95% CI, 0.16-0.71), and trials using time-limited therapy (HR, 0.28; 95% CI, 0.19-0.40).

Conclusions and Relevance

The findings of this systematic review and meta-analysis suggest that assessing MRD status as an end point in clinical trials and as a surrogate of PFS may improve trial efficiency and potentially allow for accelerated drug registration.

What clinicians should know about surrogate end points in hematologic malignancies

ABSTRACT

Use of surrogates as primary end points is commonplace in hematology/oncology clinical trials. As opposed to prognostic markers, surrogates are end points that can be measured early and yet can still capture the full effect of treatment, because it would be captured by the true outcome (eg, overall survival). We discuss the level of evidence of the most commonly used end points in hematology and share recommendations on how to apply and evaluate surrogate end points in research and clinical practice. Based on the statistical literature, this clinician-friendly review intends to build a bridge between clinicians and surrogacy specialists.

Performance of a novel eight-color flow cytometry panel for measurable residual disease assessment of chronic lymphocytic leukemia

BACKGROUND

Measurable residual disease (MRD) is an important prognostic indicator of chronic lymphocytic leukemia (CLL). Different flow cytometric panels have been developed for the MRD assessment of CLL in Western countries; however, the application of these panels in China remains largely unexplored.

METHODS

Owing to the requirements for high accuracy, reproducibility, and comparability of MRD assessment in China, we investigated the performance of a flow cytometric approach (CD45-ROR1 panel) to assess MRD in patients with CLL. The European Research Initiative on CLL (ERIC) eight-color panel was used as the "gold standard."

RESULTS

The sensitivity, specificity, and concordance rate of the CD45-ROR1 panel in the MRD assessment of CLL were 100% (87/87), 88.5% (23/26), and 97.3% (110/113), respectively. Two of the three inconsistent samples were further verified using next-generation sequencing. In addition, the MRD results obtained from the CD45-ROR1 panel were positively associated with the ERIC eight-color panel results for MRD assessment (R = 0.98, p < 0.0001). MRD detection at low levels (≤1.0%) demonstrated a smaller difference between the two methods (bias, -0.11; 95% CI, -0.90 to 0.68) than that at high levels (>1%). In the reproducibility assessment, the bias was smaller at three data points (within 24, 48, and 72 h) in the CD45-ROR1 panel than in the ERIC eight-color panel. Moreover, MRD levels detected using the CD45-ROR1 panel for the same samples from different laboratories showed a strong statistical correlation (R = 0.99, p < 0.0001) with trivial interlaboratory variation (bias, 0.135; 95% CI, -0.439 to 0.709). In addition, the positivity rate of MRD in the bone marrow samples was higher than that in the peripheral blood samples.

CONCLUSIONS

Collectively, this study demonstrated that the CD45-ROR1 panel is a reliable method for MRD assessment of CLL with high sensitivity, reproducibility, and reliability.

Minimal Residual Disease Status Predicts Outcome in Patients With Previously Untreated Follicular Lymphoma: A Prospective Analysis of the Phase III GALLIUM Study

PURPOSE

We report an analysis of minimal residual/detectable disease (MRD) as a predictor of outcome in previously untreated patients with follicular lymphoma (FL) from the randomized, multicenter GALLIUM (ClinicalTrials.gov identifier: NCT01332968) trial.

PATIENTS AND METHODS

Patients received induction with obinutuzumab (G) or rituximab (R) plus bendamustine, or cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) or cyclophosphamide, vincristine, prednisone (CVP) chemotherapy, followed by maintenance with the same antibody in responders. MRD status was assessed at predefined time points (mid-induction [MI], end of induction [EOI], and at 4-6 monthly intervals during maintenance and follow-up). Patients with evaluable biomarker data at diagnosis were included in the survival analysis.

RESULTS

MRD positivity was associated with inferior progression-free survival (PFS) at MI (hazard ratio [HR], 3.03 [95% CI, 2.07 to 4.45]; P < .0001) and EOI (HR, 2.25 [95% CI, 1.53 to 3.32]; P < .0001). MRD response was higher after G- versus R-chemotherapy at MI (94.2% v 88.9%; P = .013) and at EOI (93.1% v 86.7%; P = .0077). Late responders (MI-positive/EOI-negative) had a significantly poorer PFS than early responders (MI-negative/EOI-negative; HR, 3.11 [95% CI, 1.75 to 5.52]; P = .00011). The smallest proportion of MRD positivity was observed in patients receiving bendamustine at MI (4.8% v 16.0% in those receiving CHOP; P < .0001). G appeared to compensate for less effective chemotherapy regimens, with similar MRD response rates observed across the G-chemo groups. During the maintenance period, more patients treated with R than with G were MRD-positive (R-CHOP, 20.7% v G-CHOP, 7.0%; R-CVP, 21.7% v G-CVP, 9.4%). Throughout maintenance, MRD positivity was associated with clinical relapse.

CONCLUSION

MRD status can determine outcome after induction and during maintenance, and MRD negativity is a prerequisite for long-term disease control in FL. The higher MRD responses after G- versus R-based treatment confirm more effective tumor cell clearance.

Impact of Binet Staging versus Tumour Bulk on Treatment Outcome in Chronic Lymphocytic Leukaemia

BACKGROUND

Most of the predictive tools put up to prognosticate treatment outcomes in patients with chronic lymphocytic leukaemia (CLL) are not easily available and affordable in our resource-constrained environment.

AIM

The aim of this study was to evaluate the impact of staging and some tumour bulk on treatment outcomes of persons with CLL, Enugu, Nigeria.

PATIENTS AND METHODS

This is a 10-year review of the CLL data from the haemato-oncology unit of a Nigerian tertiary hospital to evaluate the impact of staging and tumour bulk indicators. Data were retrieved from the case notes of 102 patients with CLL receiving care at the facility. Data of interest include basic demographic variables, clinical features including spleen size and disease staging and blood counts. Statistical analysis was done using SPSS version 22.

RESULTS

The median absolute lymphocyte count (ALC) was 108.05 (confidence interval [CI] = 50.8-201.3, interquartile range [IQR] = 124.4) ×109/L, and duration of survival for the study cohort was 5.5 (CI = 3.5-31.9, IQR = 27) months. Majority (69, 79.3%) were in Stage C. The Binet stage showed a significant association with the ALC (r = 0.338; P = 0.002) but not with spleen size (r = 0.198; P = 0.056). The duration of survival only showed a significant inverse relationship with the ALC (r = 0.35, P = 0.006) but with neither the Binet stage (r = 0.103, P = 0.431) nor spleen size (r = 0.184, P = 0.116).

CONCLUSION

In CLL patients, ALC at presentation correlates with the duration of survival. We recommend that the ALC at presentation be used as a prognostic marker in our clime.

Evidence-Based Management of Chronic Lymphocytic Leukemia: Consensus Statements from the Gulf Region

INTRODUCTION

Despite recent advances in diagnosis, prognostication, and treatment options, chronic lymphocytic leukemia (CLL) is still a largely incurable disease. New concepts on diagnosis, staging, treatment, and follow-up on CLL have been incorporated throughout recent years. The lack of regional consensus guidelines has led to varying practices in the management of patients with CLL in the region. This manuscript aims to reach a consensus among expert hematologists regarding the definitions, classifications, and related practices of CLL. The experts developed a set of statements utilizing their personal experience together with the current literature on CLL management. This consensus aims to provide guidance for healthcare professionals involved in the management of CLL and serves as a step in developing regional guidelines.

METHODS

Eight experts responded to 50 statements regarding the diagnosis, staging, treatment, and prognosis of CLL with three potential answering alternatives ranging between agree, disagree, and abstain. This consensus adopted a modified Delphi consensus methodology. A consensus was reached when at least 75% of the agreement to the answer was reached. This manuscript presents the scientific insights of the participating attendees, panel discussions, and the supporting literature review.

RESULTS

Of the 50 statements, a consensus was reached on almost all statements. Statements covered CLL-related topics, including diagnostic evaluation, staging, risk assessment, different patient profiles, prognostic evaluation, treatment decisions, therapy sequences, response evaluation, complications, and CLL during the COVID-19 pandemic.

CONCLUSION

In recent years, CLL management has progressed significantly, with many diagnostic tests and several novel treatments becoming available. This consensus gathers decades of consolidated principles, novel research, and promising prospects for the management of this disease.

Prognostic Markers in the Era of Targeted Therapies

BACKGROUND

Small molecules targeting Bruton's tyrosine kinase (BTK) and B-cell lymphoma-2 have become the standard of care for the treatment of chronic lymphocytic leukemia (CLL), replacing chemoimmunotherapy (CIT) in most clinical settings. Ongoing trials explore targeted combinations and minimal residual disease-driven treatment cessation. These dramatic shifts in the current and upcoming treatment landscape of CLL raise the need to reevaluate existing prognostic markers and develop novel ones.

SUMMARY

This review examines prognostic markers in CLL patients treated with standard and investigational targeted therapies. Specifically, initial treatment of TP53 aberrant patients with a BTK inhibitor can achieve 70% progression-free survival (PFS) at 5 years, outperforming the 15% 5-year PFS with a CIT regimen containing fludarabine, cyclophosphamide, and rituximab (FCR). The prognostic implications of the immunoglobulin heavy chain variable gene (IGHV) mutation status have also changed. Unmutated IGHV is associated with inferior PFS and overall survival after FCR and inferior PFS with fixed-duration therapy with venetoclax and anti-CD20 monoclonal antibody but not with continuous BTK inhibitor treatment.

KEY MESSAGES

(1) Genetic variables (e.g., TP53 aberration, IGHV mutation, complex karyotype) have a prognostic significance in CLL patients treated with targeted therapy. (2) Understanding the prognostic and predictive values of these markers is critical for the development of a risk-adapted treatment strategy in CLL.

Impacts of early therapy response, interval to therapy interruption, and cumulative therapy interruption duration on outcome of ibrutinib therapy in relapsed/refractory chronic lymphocytic leukemia

To investigate the impact of early response and treatment interruption on the survival of patients with relapsed/refractory chronic lymphocytic leukemia or small lymphocytic lymphoma (r/r CLL/SLL) treated with ibrutinib. This post hoc analysis used data of patients received ibrutinib treatment from an open-label, multicenter phase 3 study comparing ibrutinib with rituximab in patients with r/r CLL/SLL. The association of complete or partial response at 6 months, interruption within the first 6 months, cumulative interruption durations during the ibrutinib-treated period with progression-free survival (PFS) and overall survival (OS) were evaluated using the adjusted Cox hazard proportional model. The study included 87 patients treated with ibrutinib, of which 74 patients had at least 6 months of ibrutinib treatment and were analyzed. The response at 6 months did not affect PFS (HR = 0.58, 95%CI: 0.22-1.49) or OS (HR = 0.86, 95%CI: 0.22-3.31). The onset of interruption before or after 6 months was not associated with PFS (HR = 0.88, 95%CI: 0.34-2.30) or OS (HR = 0.75, 95%CI: 0.23-2.52). However, a cumulative interruption of more than 35 days was independently associated with worse PFS (HR = 2.4, 95%CI: 0.99-5.74) and OS (HR = 2.6, 95%CI: 0.88-7.44). Continuous interruption for more than 14 days was associated with a numerically lower 3-year PFS rate (> 14 vs. ≤ 14 days: 42% vs. 73%) and 3-year OS rate (> 14 vs. ≤ 14 days: 58% vs. 84%, both P > 0.05). Response status at 6 months or early therapy interruptions did not affect survival in patients with r/r CLL/SLL treated with ibrutinib. However, a cumulative temporary interruption of more than 35 days could potentially impact patient outcomes.

Measurable Residual Disease in Chronic Lymphocytic Leukemia: Current Understanding and Evolving Role in Clinical Practice

OPINION STATEMENT

Treatment of chronic lymphocytic leukemia (CLL) has evolved dramatically during the last decade, from chemoimmunotherapy (CIT)-based therapies to newer B-cell receptor (BCR) signaling targeting agents, which are sometimes given as continuous schemes. Response to treatment was traditionally defined according to clinical variables designed to assign a response category. Interest in assessing for deeper responses in CLL by the means of measurable residual disease (MRD) testing has been the subject of research during the last several years. Analyses and sub-analyses of clinical trials have shown that achieving undetectable MRD (uMRD) in CLL is an important prognostic factor. In this review, we summarize the available evidence about MRD in CLL, from the various assays available for measurement, the compartment to test, the impact of reaching uMRD according to the treatment regimen, and the results of fixed duration treatment guided by MRD trials. Finally, we summarize how MRD can be incorporated in clinical practice and how it may guide fixed duration treatment in the future should evidence continue to accumulate in that direction.

The evolving use of measurable residual disease in chronic lymphocytic leukemia clinical trials

Measurable residual disease (MRD) status in chronic lymphocytic leukemia (CLL), assessed on and after treatment, correlates with increased progression-free and overall survival benefit. More recently, MRD assessment has been included in large clinical trials as a primary outcome and is increasingly used in routine practice as a prognostic tool, a therapeutic goal, and potentially a trigger for early intervention. Modern therapy for CLL delivers prolonged remissions, causing readout of traditional trial outcomes such as progression-free and overall survival to be inherently delayed. This represents a barrier for the rapid incorporation of novel drugs to the overall therapeutic armamentarium. MRD offers a dynamic and robust platform for the assessment of treatment efficacy in CLL, complementing traditional outcome measures and accelerating access to novel drugs. Here, we provide a comprehensive review of recent major clinical trials of CLL therapy, focusing on small-molecule inhibitors and monoclonal antibody combinations that have recently emerged as the standard frontline and relapse treatment options. We explore the assessment and reporting of MRD (including novel techniques) and the challenges of standardization and provide a comprehensive review of the relevance and adequacy of MRD as a clinical trial endpoint. We further discuss the impact that MRD data have on clinical decision-making and how it can influence a patient's experience. Finally, we evaluate how upcoming trial design and clinical practice are evolving in the face of MRD-driven outcomes.

Utility of measurable residual disease for predicting treatment outcomes with BCR- and BCL2-Targeted therapies in patients with CLL

Inhibitors targeting B-cell receptor (BCR) signaling pathway proteins and B-cell lymphoma-2 (BCL2) in chronic lymphocytic leukemia (CLL) are recommended in the first-line and relapsed/refractory disease settings. Measurable residual disease (MRD) is an important prognostic tool in patients treated with the BCL2-targeted agent, venetoclax. We explored the relationship between MRD status and progression-free (PFS)/overall survival (OS) in patients with CLL, following treatment with novel BCR- and BCL2-targeted agents. Compared with chemoimmunotherapy, higher rates of undetectable (u)MRD were achieved with BCL2-targeted therapies; achieving uMRD status was associated with longer PFS and OS than MRD-positivity. Continuous treatment with BCR-targeted agents did not achieve uMRD status in many patients, and outcomes were not correlated with uMRD status. Future clinical trials of targeted treatment combinations could be designed to demonstrate uMRD as a treatment objective, and allow a response-driven, personalized strategy to optimize treatment and improve OS outcomes.

Circulating Tumor DNA-Based MRD Assessment in Patients with CLL Treated with Obinutuzumab, Acalabrutinib, and Venetoclax

PURPOSE

With the advent of highly efficacious time-limited combination treatments of targeted agents in chronic lymphocytic leukemia (CLL), minimal residual disease (MRD) assessment has gained importance as a measure for therapeutic success and as a surrogate for progression-free survival. The currently most widely used method is multicolor flow cytometry, which detects circulating CLL cells in the peripheral blood. However, it seems to be less sensitive for the detection of MRD in the lymph node compartment.

PATIENTS AND METHODS

To evaluate whether a cell-free approach can overcome this limitation, we performed serial assessments of circulating tumor DNA (ctDNA) in patients with CLL treated with obinutuzumab, acalabrutinib, and venetoclax in the phase II CLL2-BAAG trial. Patient-specific variability, diversity, joining (VDJ) rearrangements as well as somatic driver mutations were tracked before, during and after treatment by digital droplet PCR in blood plasma. Furthermore, these were systematically compared to matched flow cytometry data.

RESULTS

In the 381 sample pairs, ctDNA and flow cytometry yielded highly concordant results. However, clone-specific ctDNA was detected in 44 of 152 samples (29%) that were assessed as undetectable MRD (uMRD) by flow cytometry (defined as less than one CLL cell in 10,000 normal leukocytes). 29 ctDNA-negative samples showed detectable MRD >10-4 by flow cytometry. Also, somatic driver mutations were detected with a similar sensitivity compared with patient-specific VDJ rearrangements in plasma. In patients with predominantly nodal residual disease, ctDNA compared favorably with 4-color flow cytometry and seemed to more accurately reflect the entire disease burden across compartments.

CONCLUSIONS

On the basis of these findings, ctDNA-based MRD assessment appears to be a promising method to complement cell-based MRD approaches like flow cytometry that focus on circulating CLL cells in the peripheral blood.

Selecting the optimal BTK inhibitor therapy in CLL: rationale and practical considerations

Bruton’s tyrosine kinase (BTK) inhibitors have dramatically changed the treatment of newly diagnosed and relapsed/refractory chronic lymphocytic leukemia (CLL). Ibrutinib, acalabrutinib, and zanubrutinib are Food and Drug Administration (FDA)-approved BTK inhibitors that have all demonstrated progression-free survival (PFS) benefit compared with chemoimmunotherapy. The efficacy of these agents compared to one another is under study; however, current data suggest they provide similar efficacy. Selectivity for BTK confers different adverse effect profiles, and longer follow-up and real-world use have characterized side effects over time. The choice of BTK inhibitor is largely patient-specific, and this review aims to highlight the differences among the agents and guide the choice of BTK inhibitor in clinical practice.

Fixed-duration ibrutinib plus venetoclax for first-line treatment of CLL: primary analysis of the CAPTIVATE FD cohort

CAPTIVATE (NCT02910583) is an international phase 2 study in patients aged ≤70 years with previously untreated chronic lymphocytic leukemia (CLL). Results from the cohort investigating fixed-duration (FD) treatment with ibrutinib plus venetoclax are reported. Patients received 3 cycles of ibrutinib lead-in then 12 cycles of ibrutinib plus venetoclax (oral ibrutinib [420 mg/d]; oral venetoclax [5-week ramp-up to 400 mg/d]). The primary endpoint was complete response (CR) rate. Hypothesis testing was performed for patients without del(17p) with prespecified analyses in all treated patients. Secondary endpoints included undetectable minimal residual disease (uMRD) rates, progression-free survival (PFS), overall survival (OS), and safety. Of the 159 patients enrolled and treated, 136 were without del(17p). The median time on study was 27.9 months, and 92% of patients completed all planned treatment. The primary endpoint was met, with a CR rate of 56% (95% confidence interval [CI], 48-64) in patients without del(17p), significantly higher than the prespecified 37% minimum rate (P < .0001). In the all-treated population, CR rate was 55% (95% CI, 48-63); best uMRD rates were 77% (peripheral blood [PB]) and 60% (bone marrow [BM]); 24-month PFS and OS rates were 95% and 98%, respectively. At baseline, 21% of patients were in the high tumor burden category for tumor lysis syndrome (TLS) risk; after ibrutinib lead-in, only 1% remained in this category. The most common grade ≥3 adverse events (AEs) were neutropenia (33%) and hypertension (6%). First-line ibrutinib plus venetoclax represents the first all-oral, once-daily, chemotherapy-free FD regimen for patients with CLL. FD ibrutinib plus venetoclax achieved deep, durable responses and promising PFS, including in patients with high-risk features.

Artificial Intelligence Enhances Diagnostic Flow Cytometry Workflow in the Detection of Minimal Residual Disease of Chronic Lymphocytic Leukemia

Flow cytometric (FC) immunophenotyping is critical but time-consuming in diagnosing minimal residual disease (MRD). We evaluated whether human-in-the-loop artificial intelligence (AI) could improve the efficiency of clinical laboratories in detecting MRD in chronic lymphocytic leukemia (CLL). We developed deep neural networks (DNN) that were trained on a 10-color CLL MRD panel from treated CLL patients, including DNN trained on the full cohort of 202 patients (F-DNN) and DNN trained on 138 patients with low-event cases (MRD < 1000 events) (L-DNN). A hybrid DNN approach was utilized, with F-DNN and L-DNN applied sequentially to cases. “Ground truth” classification of CLL MRD was confirmed by expert analysis. The hybrid DNN approach demonstrated an overall accuracy of 97.1% (95% CI: 84.7−99.9%) in an independent cohort of 34 unknown samples. When CLL cells were reported as a percentage of total white blood cells, there was excellent correlation between the DNN and expert analysis [r > 0.999; Passing−Bablok slope = 0.997 (95% CI: 0.988−0.999) and intercept = 0.001 (95% CI: 0.000−0.001)]. Gating time was dramatically reduced to 12 s/case by DNN from 15 min/case by the manual process. The proposed DNN demonstrated high accuracy in CLL MRD detection and significantly improved workflow efficiency. Additional clinical validation is needed before it can be fully integrated into the existing clinical laboratory practice.

The Minimal Residual Disease Using Liquid Biopsies in Hematological Malignancies

Simple Summary

Monitoring the response to treatment in hematologic malignancies is essential in defining the best way to optimize patient management. In general, achieving a deeper response has been shown to lead to a better prognosis, and the techniques used to study the minimal residual disease (MRD) are becoming more precise. The use of liquid biopsies, that is, analyzing the presence of alterations in nucleic acids, usually in peripheral blood or other biological fluids, is being studied and optimized with increasingly innovative molecular techniques, such as next-generation sequencing (NGS) in the monitoring of the MRD, avoiding, in many cases, more invasive tests in different hematological neoplasms. Currently, liquid biopsies are not standardized for the MRD monitoring, but there is increasing evidence of its correlation with other techniques to measure responses to treatments and patient outcomes.

Abstract

The study of cell-free DNA (cfDNA) and other peripheral blood components (known as “liquid biopsies”) is promising, and has been investigated especially in solid tumors. Nevertheless, it is increasingly showing a greater utility in the diagnosis, prognosis, and response to treatment of hematological malignancies; in the future, it could prevent invasive techniques, such as bone marrow (BM) biopsies. Most of the studies about this topic have focused on B-cell lymphoid malignancies; some of them have shown that cfDNA can be used as a novel way for the diagnosis and minimal residual monitoring of B-cell lymphomas, using techniques such as next-generation sequencing (NGS). In myelodysplastic syndromes, multiple myeloma, or chronic lymphocytic leukemia, liquid biopsies may allow for an interesting genomic representation of the tumor clones affecting different lesions (spatial heterogeneity). In acute leukemias, it can be helpful in the monitoring of the early treatment response and the prediction of treatment failure. In chronic lymphocytic leukemia, the evaluation of cfDNA permits the definition of clonal evolution and drug resistance in real time. However, there are limitations, such as the difficulty in obtaining sufficient circulating tumor DNA for achieving a high sensitivity to assess the minimal residual disease, or the lack of standardization of the method, and clinical studies, to confirm its prognostic impact. This review focuses on the clinical applications of cfDNA on the minimal residual disease in hematological malignancies.

Ibrutinib, fludarabine, cyclophosphamide, and obinutuzumab (iFCG) regimen for chronic lymphocytic leukemia (CLL) with mutated IGHV and without TP53 aberrations

Chemoimmunotherapy with combined fludarabine, cyclophosphamide and rituximab (FCR) has been an effective treatment for patients with chronic lymphocytic leukemia (CLL). We initiated a phase II trial for previously untreated patients with CLL with mutated IGHV and absence of del(17p)/TP53 mutation. Patients received ibrutinib, fludarabine, cyclophosphamide, and obinutuzumab (iFCG) for three cycles. Patients who achieved complete remission (CR)/CR with incomplete count recvoery (CRi) with marrow undetectable measurable residual disease (U-MRD) received additional nine cycles of ibrutinib with three cycles of obinutuzumab; all others received nine additional cycles of ibrutinib and obinutuzumab. Patients in marrow U-MRD remission after cycle 12 discontinued all treatment, including ibrutinib. Forty-five patients were treated. The median follow-up is 41.3 months. Among the total 45 treated patients, after three cycles, 38% achieved CR/CRi and 87% achieved marrow U-MRD. After cycle 12, the corresponding numbers were 67% and 91%, respectively. Overall, 44/45 (98%) patients achieved marrow U-MRD as best response. No patient had CLL progression. The 3-year progression-free survival (PFS) and overall survival (OS) were 98% and 98%, respectively. Per trial design, all patients who completed cycle 12 discontinued ibrutinib, providing for a time-limited therapy. Grade 3-4 neutropenia and thrombocytopenia occurred in 58% and 40% patients, respectively. The iFCG regimen with only 3 cycles of chemotherapy is an effective, time-limited regimen for patients with CLL with mutated IGHV and without del(17p)/TP53 mutation.

Ibrutinib Plus Venetoclax for First-Line Treatment of Chronic Lymphocytic Leukemia: Primary Analysis Results From the Minimal Residual Disease Cohort of the Randomized Phase II CAPTIVATE Study

PURPOSE

CAPTIVATE (NCT02910583), a randomized phase II study, evaluates minimal residual disease (MRD)-guided treatment discontinuation following completion of first-line ibrutinib plus venetoclax treatment in patients with chronic lymphocytic leukemia (CLL).

METHODS

Previously untreated CLL patients age < 70 years received three cycles of ibrutinib and then 12 cycles of combined ibrutinib plus venetoclax. Patients in the MRD cohort who met the stringent random assignment criteria for confirmed undetectable MRD (Confirmed uMRD) were randomly assigned 1:1 to double-blind placebo or ibrutinib; patients without Confirmed uMRD (uMRD Not Confirmed) were randomly assigned 1:1 to open-label ibrutinib or ibrutinib plus venetoclax. Primary end point was 1-year disease-free survival (DFS) rate with placebo versus ibrutinib in the Confirmed uMRD population. Secondary end points included response rates, uMRD, and safety.

RESULTS

One hundred sixty-four patients initiated three cycles of ibrutinib lead-in. After 12 cycles of ibrutinib plus venetoclax, best uMRD response rates were 75% (peripheral blood) and 68% (bone marrow). Patients with Confirmed uMRD were randomly assigned to receive placebo (n = 43) or ibrutinib (n = 43); patients with uMRD Not Confirmed were randomly assigned to ibrutinib (n = 31) or ibrutinib plus venetoclax (n = 32). Median follow-up was 31.3 months. One-year DFS rate was not significantly different between placebo (95%) and ibrutinib (100%; arm difference: 4.7% [95% CI, -1.6 to 10.9]; P = .15) in the Confirmed uMRD population. After ibrutinib lead-in tumor debulking, 36 of 40 patients (90%) with high tumor lysis syndrome risk at baseline shifted to medium or low tumor lysis syndrome risk categories. Adverse events were most frequent during the first 6 months of ibrutinib plus venetoclax and generally decreased over time.

CONCLUSION

The 1-year DFS rate of 95% in placebo-randomly assigned patients with Confirmed uMRD suggests the potential for fixed-duration treatment with this all-oral, once-daily, chemotherapy-free regimen in first-line CLL.

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.

A fixed-duration, measurable residual disease-guided approach in CLL: follow-up data from the phase 2 ICLL-07 FILO trial

Trials assessing first-line, fixed-duration approaches in chronic lymphocytic leukemia (CLL) are yielding promising activity, but few long-term data are available. We report follow-up data from a phase 2 trial (ICLL07 FILO) in previously untreated, medically fit patients (N = 135). Patients underwent obinutuzumab-ibrutinib induction for 9 months; then, following evaluation (N = 130 evaluable), those in complete remission and with bone marrow measurable residual disease (BM MRD) <0.01% (n = 10) received ibrutinib for 6 additional months; those in partial remission and/or with BM MRD ≥0.01%, the majority (n = 120), also received 4 cycles of immunochemotherapy (fludarabine/cyclophosphamide-obinutuzumab). Beyond end of treatment, responses were assessed every 3 month and peripheral blood MRD every 6 months. At median follow-up 36.7 months from treatment start, progression-free and overall survival rates (95% confidence interval) at 3 years were 95.7% (92.0% to 99.5%) and 98% (95.1% to 100%), respectively. Peripheral blood MRD <0.01% rates were 97%, 96%, 90%, 84%, and 89% at months 16, 22, 28, 34, and 40, respectively. No new treatment-related or serious adverse event occurred beyond end of treatment. Thus, in previously untreated, medically fit patients with CLL, a fixed-duration (15 months), MRD-guided approach achieved high survival rates, a persistent MRD benefit beyond the end of treatment, and low long-term toxicity. This trial was registered at www.clinicaltrials.gov as #NCT02666898.

Venetoclax alone or in combination with other regimens treatment achieve deep and sustained remission of relapsed/refractory chronic lymphocytic leukemia: a meta-analysis

Recently, the use of novel targeted drugs significantly improved the overall response rate (ORR) and survival of patients with relapsed/refractory chronic lymphocytic leukemia (R/R CLL). The treatment of R/R CLL has been gradually developed from traditional chemotherapy to targeted therapy. Venetoclax has been proved to be effective for R/R CLL as a single agent or in combination with various regimens. However, the data from clinical studies were still limited, especially since a large number of studies were single arms. Considering that there were few kinds of research in this regard and the data were not uniform, a meta-analysis was conducted to describe ORR and undetectable minimal residual disease (uMRD) of venetoclax in patients with R/R CLL. The pooled cumulative prevalence of total ORR was 82% (95% CI 77-87%), and the pooled ORR in venetoclax + anti-CD20 antibody-based group was 89% (95% CI 83-94%). There were significant differences among venetoclax monotherapy group, venetoclax + ibrutinib group and venetoclax + anti-CD20 group with pooled uMRD of 39% (95% CI 31-47%), 57% (95% CI 50-64%) and 43% (95% CI 19-70%), respectively (P = 0.004 < 0.05). Pooled ORR of patients with high-risk cytogenetic in venetoclax monotherapy group was 73% (95% CI 61-83%). No significant difference was observed in comparison with patients without high-risk cytogenetic who received the same treatment (P = 0.518). Our research results indicate that venetoclax combined with anti-CD20 monoclonal antibody may be an effective treatment for patients with R/R CLL, especially for CLL patients with high-risk cytogenetic factors. Furthermore, ibrutinib in combination with venetoclax showed a longer remission time, the deeper remission degree and uMRD-negative rate gradually increased with the extension of the treatment time.

Immune Gene Rearrangements: Unique Signatures for Tracing Physiological Lymphocytes and Leukemic Cells

The tremendous diversity of the human immune repertoire, fundamental for the defense against highly heterogeneous pathogens, is based on the ingenious mechanism of immune gene rearrangements. Rearranged immune genes encoding the immunoglobulins and T-cell receptors and thus determining each lymphocyte's antigen specificity are very valuable molecular markers for tracing malignant or physiological lymphocytes. One of their most significant applications is tracking residual leukemic cells in patients with lymphoid malignancies. This so called 'minimal residual disease' (MRD) has been shown to be the most important prognostic factor across various leukemia subtypes and has therefore been given enormous attention. Despite the current rapid development of the molecular methods, the classical real-time PCR based approach is still being regarded as the standard method for molecular MRD detection due to the cumbersome standardization of the novel approaches currently in progress within the EuroMRD and EuroClonality NGS Consortia. Each of the molecular methods, however, poses certain benefits and it is therefore expectable that none of the methods for MRD detection will clearly prevail over the others in the near future.

Should Undetectable Minimal Residual Disease Be the Goal of Chronic Lymphocytic Leukemia Therapy?

With the advent of highly effective novel therapies for chronic lymphocytic leukemia, conventional response assessment is not able to sensitively capture depth of response. To achieve a more precise assessment of response, minimal residual disease has been introduced to more accurately classify and quantify treatment outcomes. It is now considered a strong predictor of outcome in chronic lymphocytic leukemia, although its interpretation depends on the therapeutic context. This review discusses available methods of minimal residual disease measurement. It summarizes minimal residual disease data from pivotal clinical trials and discusses potential implications for future studies and minimal residual disease-based clinical strategies.

Stance of MRD in Non-Hodgkin's Lymphoma and its upsurge in the novel era of cell-free DNA

Cancer genomics has evolved over the years from understanding the pathogenesis of cancer to screening the future possibilities of cancer occurrence. Understanding the genetic profile of tumors holds a prognostic as well as a predictive value in this era of therapeutic surveillance, molecular remission, and precision medicine. Identifying molecular markers in tumors is the current standard of approach, and requires an efficient combination of an accessible sample type and a profoundly sensitive technique. Liquid biopsy or cell-free DNA has evolved as a novel sample type with promising results in recent years. Although cell-free DNA has significant role in various cancer types, this review focuses on its application in Non-Hodgkin's Lymphoma. Beginning with the current concept and clinical relevance of minimal residual disease in Non-Hodgkin's lymphoma, we discuss the literature on circulating DNA and its evolving application in the realm of cutting-edge technology.

Current and future treatment strategies in chronic lymphocytic leukemia

Treatment decisions for patients with chronic lymphocytic leukemia (CLL) are dependent on symptoms and classification into high-, medium-, or low-risk categories. The prognosis for CLL hinges, in part, on the presence or absence of less-favorable genetic aberrations, including del(17p), del(11q), TP53 dysfunction, and IGHV mutations, as these markers are associated with worse treatment response. Promising results from multiple clinical trials show emerging therapies targeting Burton tyrosine kinase, B-cell leukemia/lymphoma 2, and phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit delta result in better outcomes and prolonged progression-free survival for patients both with and without certain high-risk aberrations. Favorable outcomes using these novel oral targeted therapies, either alone or in combination with other treatments such as anti-CD20 antibodies, has led to their use almost entirely supplanting chemoimmunotherapy in the treatment of CLL. In this narrative review, we summarize the current clinical evidence for the use of targeted mono- and combination therapies for CLL, discuss new and next-generation treatment approaches currently in development, and provide insight into areas of unmet need for the treatment of patients with CLL.

Incorporating molecular biomarkers into the continuum of care in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a mature B-cell malignancy characterized by marked heterogeneity. Discoveries in disease biology over the past two decades have helped explain clinical variability and heralded the arrival of the targeted therapy era. In this article, we review improvements in risk stratification which have coincided with this progress, including individual biomarkers and their incorporation into prognostic models. Amidst an ever-expanding list of biomarkers, we seek to bring focus to the essential tests to improve patient care and counseling at particular times in the disease course, beginning with prognosis at diagnosis. The majority of patients do not require treatment at the time of diagnosis, making time-to-first-treatment a key initial prognostic concern. Prognostic and predictive biomarkers are then considered at subsequent major junctures, including at the time of treatment initiation, while on therapy, and at the time of relapse on novel agents.

Highly Sensitive and Accurate Assessment of Minimal Residual Disease in Chronic Lymphocytic Leukemia Using the Novel CD160-ROR1 Assay

Undetectable minimal residual disease (MRD) in Chronic Lymphocytic Leukemia (CLL) has a favorable prognostic outcome compared with MRD that can be detected. This study investigated a flow cytometric assay (CD160-ROR1FCA) targeting the tumor-specific antigens CD160 and receptor tyrosine kinase-like orphan receptor 1 (ROR1), along with CD2, CD5, CD19, CD45. CD160-ROR1FCA was compared with the originally published 8-colour European Research Initiative for CLL (ERIC) gold-standard assay for CLL MRD detection. CD160-ROR1FCA had a limit of detection of 0.001% and showed strong correlation with ERIC (R = 0.98, p < 0.01) with negligible differences in MRD detection (bias -0.3152 95%CI 5.586 to -6.216). Using CD160-ROR1FCA, increased expression of both CD160 and ROR1 was found in Monoclonal B cell Lymphocytosis (MBL) compared to low-level polyclonal B-cell expansions (p < 0.01). Patients in CR and with undetectable MRD had a longer EFS (not reached) than those in CR but with detectable MRD (756 days, p < 0.01) versus 113 days in patients with partial remission (p < 0.01). Patients with MRD levels of >0.01 to 0.1% had a longer EFS (2,333 days), versus levels between 0.1 to 1% (1,049 days). CD160-ROR1FCA is a novel assay for routine CLL MRD measurement and for MBL detection. MRD status assessed by CD160-ROR1FCA after CLL treatment correlated with EFS.

Is There a Role for Chemotherapy in the Era of Targeted Therapies?

PURPOSE OF REVIEW

The treatment landscape of chronic lymphocytic leukemia has been rapidly evolving over the past few years. The prior standard of care, chemoimmunotherapy, is being replaced by targeted agents, and the utility of chemotherapy has come under question. In this review, we examine recent data comparing chemoimmunotherapy to targeted agents, how these data impact clinical management, and whether there are potential future roles for cytotoxic chemotherapy.

RECENT FINDINGS

Clinical trials have shown improved clinical outcomes with targeted agents compared to traditional chemoimmunotherapy. Based on these data, the current treatment paradigm primarily favors targeted agents over chemoimmunotherapy, with a few exceptions. However, targeted agents have notable limitations, and thus, there may be a future role of cytotoxic chemotherapy when administered in combination with targeted agents. Although targeted agents have nearly replaced chemoimmunotherapy in the treatment of chronic lymphocytic leukemia, novel combinations utilizing chemotherapy are being developed that may lead to better outcomes.

Treatment algorithm for Japanese patients with chronic lymphocytic leukemia in the era of novel targeted therapies

Treatment for patients with chronic lymphocytic leukemia (CLL) is becoming more individualized due to the recent introduction of novel molecularly targeted therapies into the therapeutic armamentarium. Genomic and molecular risk factors in CLL patients determine the individual risk for disease progression and response to therapy, and can impact survival. In this review article, we discuss current treatment strategies for CLL patients in Japan, where the novel targeted agents, the BTK inhibitor ibrutinib and BCL2 antagonist venetoclax, now are available and increasingly used in clinical practice. We also discuss the importance of CLL risk factors for making therapy decisions, focusing on immunoglobulin variable region heavy chain (IGHV) mutation status, 11q deletion, and 17p deletion. Treatment approaches for CLL have rapidly changed in the past few years because of these new targeted agents. They are highly effective, well tolerated, and have been demonstrated in a series of large randomized clinical trials to improve survival when compared with conventional chemotherapy-based treatment. Therefore, for most patients, especially high-risk CLL patients, BTK inhibitor and BCL2 antagonist therapies are preferred over chemo-immunotherapy. Currently ongoing studies seek to determine the best sequence for these new agents and whether a combination therapy approach is beneficial. With these developments, a new era of chemotherapy-free treatment for CLL patients is expected.

Prognostic value of high-sensitivity measurable residual disease assessment after front-line chemoimmunotherapy in chronic lymphocytic leukemia

Measurable residual disease (MRD) status is widely adopted in clinical trials in patients with chronic lymphocytic leukemia (CLL). Findings from FILO group trials (CLL2007FMP, CLL2007SA, CLL2010FMP) enabled investigation of the prognostic value of high-sensitivity (0.7 × 10^-5) MRD assessment using flow cytometry, in blood (N = 401) and bone marrow (N = 339), after fludarabine, cyclophosphamide, and rituximab (FCR)-based chemoimmunotherapy in a homogeneous population with long follow-up (median 49.5 months). Addition of low-level positive MRD < 0.01% to MRD ≥ 0.01% increased the proportion of cases with positive MRD in blood by 39% and in bone marrow by 27%. Compared to low-level positive MRD < 0.01%, undetectable MRD was associated with significantly longer progression-free survival (PFS) when using blood (72.2 versus 42.7 months; hazard ratio 0.40, p = 0.0003), but not when using bone marrow. Upon further stratification, positive blood MRD at any level, compared to undetectable blood MRD, was associated with shorter PFS irrespective of clinical complete or partial remission, and a lower 5-year PFS rate irrespective of IGHV-mutated or -unmutated status (all p < 0.05). In conclusion, high-sensitivity (0.0007%) MRD assessment in blood yielded additional prognostic information beyond the current standard sensitivity (0.01%). Our approach provides a model for future determination of the optimal MRD investigative strategy for any regimen.

14-Color single tube for flow cytometric characterization of CD5+ B-LPDs and high sensitivity automated minimal residual disease quantitation of CLL/SLL

INTRODUCTION

The diagnosis of CLL/SLL relies on flow cytometric immunophenotyping. Increasing emphasis is being placed on precise detection of the minimal residual disease. Following antigen recommendations of ERIC and ESCCA's Harmonization Project, we validated a 14-color assay for the characterization CD5+ lymphoproliferative neoplasms and CLL MRD with a sensitivity of at least 10^-4 .

METHODS

The assay was designed based on ERIC/ESCCA recommended antigens with the addition of CD40 for alternate gating when CD19 expression is reduced. Lower limit of quantitation/lower limit of detection, assay procedural precision, linearity, and limit of blank were established. Then, 52 CD5+ B-cell lymphoproliferative neoplasms (41 CLL/11 non-CLL) and 29 normal samples were used for parallel evaluation. Automated cluster identification and quantitation of CLL clones in MRD setting was performed using Barned-Hutt SNE. Separation analysis between CLL and non-CLL phenotypes was performed by PCA and bh-SNE.

RESULTS

Separation ratios for each antigen exceeded ERIC/ESCCA guidelines. Precision was <20% at LLOQ (0.01%). The limit of blank was <10/500,000 cells. Concordance between the 14-color and legacy assay (Deming regression y = 1.01x, r²  = .99) was seen. All 20 samples with MRD levels 0.5%-0.006% (median 0.04%) showed an abnormal cell cluster by bh-SNE, with concordant results between manual and automated quantitation (y = x, r²  = 1). CLL cases clustered together and away from mantle cell lymphoma by bh-SNE and PCA with outlier atypical phenotype CLL cases posing diagnostic challenges by both manual and automated analysis.

CONCLUSION

The 14-color CD5+ LPD assay provides a robust standardization platform for MRD and disease characterization using both manual and automated analysis.

A phase 1b/2 study of duvelisib in combination with FCR (DFCR) for frontline therapy for younger CLL patients

Fludarabine, cyclophosphamide, and rituximab (FCR) is highly effective initial therapy for younger patients with chronic lymphocytic leukemia (CLL); however, most eventually relapse. Duvelisib is a delta/gamma PI3K inhibitor approved for relapsed/refractory CLL. We conducted an investigator-initiated, phase 1b/2 study of duvelisib + FCR (DFCR) as initial treatment for CLL patients aged ≤65. A standard 3 + 3 design included two dose levels of duvelisib (25 mg qd and 25 mg bid). Duvelisib was given for 1 week, then with standard FCR added for up to six 28-day cycles, then up to 2 years of duvelisib maintenance. Thirty-two patients were enrolled. The phase 2 dose of duvelisib was identified as 25 mg bid. Hematologic toxicity was common, and all-grade non-hematologic toxicities included transaminitis (28%), febrile neutropenia (22%), pneumonia (19%), and colitis (6%). The best overall response rate by ITT was 88% (56% CR/CRi and 32% PR). The best rate of bone marrow undetectable minimal residual disease (BM-uMRD) by ITT was 66%. The rate of CR with BM-uMRD at end of combination treatment (primary endpoint) was 25%. Three-year PFS and OS are 73 and 93%, respectively. DFCR is active as initial therapy of younger CLL patients. Immune-mediated and infectious toxicities occurred and required active management.

Relevance of Minimal Residual Disease in the Era of Targeted Agents

The evaluation of minimal residual disease (MRD) in chronic lymphocytic leukemia (CLL) has evolved in parallel with the enormous progresses in the therapeutic armamentarium and the application of cutting-edge diagnostic techniques the CLL community witnessed in the past few years. Minimal residual disease is considered an objective measure of disease status defined by the number of residual leukemic cells detected in a sample of peripheral blood and/or bone marrow as proportion of the total white blood cells and defined undetectable if fewer than 1 CLL cell among 10,000 white blood cells (10 or 0.01%) is detected. In this review, we aim at shedding light on how to evaluate MRD, what we already know about MRD from the experience with chemoimmunotherapy, and why MRD evaluation remains still relevant in the era of targeted agents.

Venetoclax for the Treatment of Chronic Lymphocytic Leukemia

PURPOSE OF THIS REVIEW

This review summarizes the role of BCL-2 in the pathogenesis of CLL, and the clinical data evaluating safety and efficacy of venetoclax, in treatment of patients with CLL, in the context of other available targeted agents.

RECENT FINDINGS

Venetoclax, alone or in combination with other targeted agents results in high rate of durable responses and undetectable measurable residual disease. Venetoclax maintains activity across all clinical and biologic subgroups, including those with high risk disease, including CLL with chromosome 17p deletion. TLS risk can be mitigated with risk stratification and five-week administration ramp-up schedule. Venetoclax, a novel, orally bioavailable inhibitor of BCL-2 has demonstrated substantial clinical activity in the treatment of CLL. In combination with other targeted agents it can induce high disease response rates and potentially lead to MRD-negative durable remissions.

How to manage lymphoid malignancies during novel 2019 coronavirus (CoVid-19) outbreak: a Brazilian task force recommendation

The novel Coronavirus (CoVid-19) outbreak is now consider a world pandemic, affecting more than 1,300,000 people worldwide. Cancer patients are in risk for severe disease, including a higher risk of intensive care unit (ICU) admission, need for invasive ventilation or death. Management of patients with lymphoid malignancies can be challenging during the outbreak, due to need of multiple hospital visits and admissions, immunosuppression and need for chemotherapy, radiotherapy and stem cell transplantation. In this article, we will focus on the practical management of patients with lymphoid malignancies during the COVID-19 pandemic, focusing on minimizing the risk for patients.

Minimal residual disease undetectable by next-generation sequencing predicts improved outcome in CLL after chemoimmunotherapy

Patients with chronic lymphocytic leukemia (CLL) who achieve blood or bone marrow (BM) undetectable minimal residual disease (U-MRD) status after first-line fludarabine, cyclophosphamide, and rituximab (FCR) have prolonged progression-free survival (PFS), when assessed by an assay with sensitivity 10-4 (MRD4). Despite reaching U-MRD4, many patients, especially those with unmutated IGHV, subsequently relapse, suggesting residual disease <10-4 threshold and the need for more sensitive MRD evaluation. MRD evaluation by next-generation sequencing (NGS) has a sensitivity of 10-6 (MRD6). To better assess the depth of remission following first-line FCR treatment, we used NGS (Adaptive Biotechnologies Corporation) to assess MRD in 62 patients, all of whom had BM U-MRD by multicolor flow cytometry (sensitivity 10-4) at end-of-FCR treatment. Samples from these patients included 57 BM samples, 29 peripheral blood mononuclear cell (PBMC) samples, and 32 plasma samples. Only 27.4% of the 62 patients had U-MRD by NGS. Rate of U-MRD by NGS was lowest in BM (25%), compared with PBMC (55%) or plasma (75%). No patient with U-MRD by NGS in BM or PBMC was MRD+ in plasma. Patients with mutated IGHV were more likely to have U-MRD by NGS at the end of treatment (EOT; 41% vs 13%, P = .02) than those with unmutated IGHV. Median follow-up was 81.6 months. Patients with U-MRD at EOT had superior PFS vs MRD+ patients, regardless of sample type assessed (BM, P = .02, median not reached [NR] vs 67 months; PBMC, P = .02, median NR vs 74 months). More sensitive MRD6 testing increases prognostic discrimination over MRD4 testing.

Chronic Lymphocytic Leukaemia in 2020: the Future Has Arrived

PURPOSE OF REVIEW

Chronic lymphocytic leukaemia is now recognised as a heterogenous disease with a variety of clinical outcomes. Here we summarise the way it is currently stratified according to genetic risk and patient characteristics and the treatment approaches used for these different subgroups.

RECENT FINDINGS

Certain patients appear to sustain MRD negativity after combination chemoimmunotherapy, leading to the suggestion that their CLL may be cured. However, 17p-deleted, p53-mutated or IGHV-UM subgroups are generally resistant to FCR, and much better responses are seen with ibrutinib and venetoclax, frequently inducing MRD negativity that hopefully will be translated into durable remissions. Small molecule inhibitors have already revolutionised CLL treatment. Going forward, we anticipate their use in the majority of patients, early after diagnosis and with curative intent.

Obinutuzumab plus fludarabine and cyclophosphamide in previously untreated, fit patients with chronic lymphocytic leukemia: a subgroup analysis of the GREEN study

GREEN (NCT01905943) is a nonrandomized, open-label, single-arm, phase 3b study investigating the safety and efficacy of obinutuzumab alone or in combination with chemotherapy in chronic lymphocytic leukemia (CLL). We report the preplanned subgroup analysis of 140 previously untreated, fit CLL patients who received obinutuzumab plus fludarabine and cyclophosphamide (G-FC). The primary endpoint was safety and tolerability. Efficacy was the secondary endpoint. Obinutuzumab 1000 mg was administered intravenously on Day (D)1 (dose split D1‒2), D8 and D15 of Cycle (C)1, and D1 of C2-6 (28-day cycles). Standard intravenous/oral doses of fludarabine and cyclophosphamide were administered on D1-3 of C1-6. Overall, 87.1% of patients experienced grade ≥ 3 adverse events (AEs), including neutropenia (67.1%) and thrombocytopenia (17.1%). Serious AEs were experienced by 42.1% of patients. Rates of grade ≥ 3 infusion-related reactions and infections were 19.3% and 15.7%, respectively. Overall response rate was observed in 90.0%, with 46.4% of patients achieving complete response (CR; including CR with incomplete marrow recovery). Minimal residual disease negativity rates were 64.3% in peripheral blood and 35.7% in bone marrow (intent-to-treat analysis). After a median observation time of 25.6 months, 2 year progression-free survival was 91%. Frontline G-FC represents a promising treatment option for fit patients with CLL.

Minimal Residual Disease Assessment in CLL: Ready for Use in Clinical Routine?

The introduction of chemoimmunotherapy and more recently the implementation of novel agents into first-line and relapse treatment have substantially improved treatment outcomes in patients with chronic lymphocytic leukaemia (CLL). With longer progression-free survival and more frequently observed deep remissions there is an emerging need for sensitive methods quantitating residual disease after therapy. Over the last decade, assessment of minimal residual disease (MRD) has increasingly been implemented in CLL trials. The predictive value of MRD status on survival outcomes has repeatedly been proven in the context of chemoimmunotherapy and cellular therapies. Recent data suggests a similar correlation for Bcl-2 inhibitor-based therapy. While the relevance of MRD assessment as a surrogate endpoint in clinical trials is largely undisputed, its role in routine clinical practice has not yet been well defined. This review outlines current methods of MRD detection in CLL and summarizes MRD data from relevant trials. The significance of MRD testing in clinical studies and in routine patient care is assessed and new MRD-guided treatment strategies are discussed.

Minimal Residual Disease in Chronic Lymphocytic Leukemia: A New Goal?

In chronic lymphocytic leukemia (CLL), there is a growing interest for minimal residual disease (MRD) monitoring, due to the availability of drug combinations capable of unprecedented complete clinical responses. The standardized and most commonly applied methods to assess MRD in CLL are based on flow cytometry (FCM) and, to a lesser extent, real-time quantitative PCR (RQ-PCR) with allele-specific oligonucleotide (ASO) primers of immunoglobulin heavy chain genes (IgH). Promising results are being obtained using droplet digital PCR (ddPCR) and next generation sequencing (NGS)-based approaches, with some advantages and a potential higher sensitivity compared to the standardized methodologies. Plasma cell-free DNA can also be explored as a more precise measure of residual disease from all different compartments, including the lymph nodes. From a clinical point of view, CLL MRD quantification has proven an independent prognostic marker of progression-free survival (PFS) and overall survival (OS) after chemoimmunotherapy as well as after allogeneic transplantation. In the era of mechanism-driven drugs, the paradigms of CLL treatment are being revolutionized, challenging the use of chemoimmunotherapy even in first-line. The continuous administration of ibrutinib single agent has led to prolonged PFS and OS in relapsed/refractory and treatment naïve CLL, including those with TP53 deletion/mutation or unmutated IGHV genes, though the clinical responses are rarely complete. More recently, chemo-free combinations of venetoclax+rituximab, venetoclax+obinutuzumab or ibrutinib+venetoclax have been shown capable of inducing undetectable MRD in the bone marrow, opening the way to protocols exploring a MRD-based duration of treatment, aiming at disease eradication. Thus, beside a durable disease control desirable particularly for older patients and/or for those with comorbidities, a MRD-negative complete remission is becoming a realistic prospect for CLL patients in an attempt to obtain a long-lasting eradication and possibly cure of the disease. Here we discuss the standardized and innovative technical approaches for MRD detection in CLL, the clinical impact of MRD monitoring in chemoimmunotherapy and chemo-free trials and the future clinical implications of MRD monitoring in CLL patients outside of clinical trials.

Presenting features and treatment outcomes of chronic lymphocytic leukaemia in a resource poor Southern Nigeria

Background

Chronic lymphocytic leukaemia is a relatively common haematological malignancy affecting older adults, accounting for about 20% of haematological malignancies in Nigeria. Diagnosis of this disease depends on the demonstration of clonal lymphocytosis > 5 × 109/L with a characteristic immunophenotypic pattern amidst other clinical and laboratory features.

Objectives

To determine the predominant clinical and laboratory features of CLL at presentation and their relationship with patient survival. This study also aims at examining the relationship between treatment protocol and outcome.

Methods

This is a retrospective study with 8 years data (2010–2018) collected from four different centers. Data was analyzed using SPSS 20.0.

Results

There were a total of 97 cases, with a male: female ratio of 1.1:1. The median age at presentation was 59 years. Approximately 55% of the patients presented at Binet stage C, with splenomegaly in 93.2% and 78% were anaemic. The mean white cell count was 137.9 ± 14.7 × 109/L, with a median absolute lymphocyte count of 86 × 109/L. The commonest treatment regimen was chlorambucil and prednisolone and males had a superior response. The number of chemotherapy cycles, serum alkaline phosphatase and aspartate transaminase correlated positively with duration of survival. Mortality rate over the five year period was 14.3%.

Conclusion

CLL was found to present in younger patients when compared to previous studies with a median age of 57 years at diagnosis. Our study showed a slight female preponderance and better response to therapy in males. Majority of the patients presented in Binet stage C and were treated with chlorambucil-based drug combinations compared to more current treatment with Fludarabine-based combinations. A high serum alanine transaminase and alkaline phosphatase was found to positively correlate with survival amongst this patient population

Prognostic role of CD4 T-cell depletion after frontline fludarabine, cyclophosphamide and rituximab in chronic lymphocytic leukaemia

BACKGROUND

Eradication of minimal residual disease (MRD), at the end of Fludarabine-Cyclophosphamide-Rituximab (FCR) treatment, is a validated surrogate marker for progression-free and overall survival in chronic lymphocytic leukaemia. But such deep responses are also associated with severe immuno-depletion, leading to infections and the development of secondary cancers.

METHODS

We assessed, blood MRD and normal immune cell levels at the end of treatment, in 162 first-line FCR patients, and analysed survival and adverse event.

RESULTS

Multivariate Landmark analysis 3 months after FCR completion identified unmutated IGHV status (HR, 2.03, p = 0.043), the level of MRD reached (intermediate versus low, HR, 2.43, p = 0.002; high versus low, HR, 4.56, p = 0.002) and CD4 > 200/mm3 (HR, 3.30, p <  0.001) as factors independently associated with progression-free survival (PFS); neither CD8 nor NK counts were associated with PFS. The CD4 count was associated with PFS irrespective of IGHV mutational status, but only in patients with detectable MRD (HR, 3.51, p = 0.0004, whereas it had no prognostic impact in MRD < 10- 4 patients: p = 0.6998). We next used a competitive risk model to investigate whether immune cell subsets could be associated with the risk of infection and found no association between CD4, CD8 and NK cells and infection.

CONCLUSIONS

Consolidation/maintenance trials based on detectable MRD after FCR should investigate CD4 T-cell numbers both as a selection and a response criterion, and consolidation treatments should target B-cell/T-cell interactions.

Ibrutinib plus fludarabine, cyclophosphamide, and rituximab as initial treatment for younger patients with chronic lymphocytic leukaemia: a single-arm, multicentre, phase 2 trial

BACKGROUND

Fludarabine, cyclophosphamide, and rituximab (FCR) can improve disease-free survival for younger (age ≤65 years) fit patients with chronic lymphocytic leukaemia with mutated IGHV. However, patients with unmutated IGHV rarely have durable responses. Ibrutinib is active for patients with chronic lymphocytic leukaemia irrespective of IGHV mutation status but requires continuous treatment. We postulated that time-limited ibrutinib plus FCR would induce durable responses in younger fit patients with chronic lymphocytic leukaemia.

METHODS

We did a multicentre, open-label, non-randomised, single-arm phase 2 trial at seven sites in the USA. We enrolled patients aged 65 years or younger with previously untreated chronic lymphocytic leukaemia. Our initial cohort (original cohort) was not restricted by prognostic marker status and included patients who had del(17p) or TP53 aberrations. After a protocol amendment (on March 21, 2017), we enrolled an additional cohort (expansion cohort) that included patients without del(17p). Ibrutinib was given orally (420 mg/day) for 7 days, then up to six 28-day cycles were administered intravenously of fludarabine (25 mg/m2, days 1-3), cyclophosphamide (250 mg/m2, days 1-3), and rituximab (375 mg/m2 day 1 of cycle 1; 500 mg/m2 day 1 of cycles 2-6) with continuous oral ibrutinib (420 mg/day). Responders continued on ibrutinib maintenance for up to 2 years, and patients with undetectable minimal residual disease in bone marrow after 2 years were able to discontinue treatment. The primary endpoint was the proportion of patients who achieved a complete response with undetectable minimal residual disease in bone marrow 2 months after the last cycle of ibrutinib plus FCR. Analyses were done per-protocol in all patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov (NCT02251548) and is ongoing.

FINDINGS

Between Oct 23, 2014, and April 23, 2018, 85 patients with chronic lymphocytic leukaemia were enrolled. del(17p) was detected in four (5%) of 83 patients and TP53 mutations were noted in three (4%) of 81 patients; two patients had both del(17p) and TP53 mutations. Median patients' age was 55 years (IQR 50-58). At data cutoff, median follow-up was 16·5 months (IQR 10·6-34·1). A complete response and undetectable minimal residual disease in bone marrow 2 months after the last cycle of ibrutinib plus FCR was achieved by 28 (33%, 95% CI 0·23-0·44) of 85 patients (p=0·0035 compared with a 20% historical value with FCR alone). A best response of undetectable minimal residual disease in bone marrow was achieved by 71 (84%) of 85 patients during the study. One patient had disease progression and one patient died (sudden cardiac death after 17 months of ibrutinib maintenance, assessed as possibly related to ibrutinib). The most common all-grade toxic effects were haematological, including thrombocytopenia in 63 (74%) patients, neutropenia in 53 (62%), and anaemia in 41 (49%). Grade 3 or 4 non-haematological serious adverse events included grade 3 atrial fibrillation in three (4%) patients and grade 3 Pneumocystis jirovecii pneumonia in two (2%).

INTERPRETATION

The proportion of patients who achieved undetectable minimal residual disease in bone marrow with ibrutinib plus FCR is, to our knowledge, the highest ever published in patients with chronic lymphocytic leukaemia unrestricted by prognostic marker status. Ibrutinib plus FCR is promising as a time-limited combination regimen for frontline chronic lymphocytic leukaemia treatment in younger fit patients.

FUNDING

Pharmacyclics and the Leukemia & Lymphoma Society.

Obinutuzumab and ibrutinib induction therapy followed by a minimal residual disease-driven strategy in patients with chronic lymphocytic leukaemia (ICLL07 FILO): a single-arm, multicentre, phase 2 trial

BACKGROUND

In patients with chronic lymphocytic leukaemia, achievement of a complete response with minimal residual disease of less than 0·01% (ie, <1 chronic lymphocytic leukaemia cell per 10 000 leukocytes) in bone marrow has been associated with improved progression-free survival. We aimed to explore the activity of induction therapy for 9 months with obinutuzumab and ibrutinib, followed up with a minimal residual disease-driven therapeutic strategy for 6 additional months, in previously untreated patients.

METHODS

We did a single-arm, phase 2 trial in 27 university hospitals, general hospitals, and specialist cancer centres in France. Eligible patients were at least 18 years old and previously untreated, and had immunophenotypically confirmed B-cell chronic lymphocytic leukaemia; an Eastern Cooperative Oncology Group (ECOG) performance status score of less than 2; a Binet stage C according to IWCLL 2008 criteria or Binet stage A and B with active disease; no 17p deletion or absence of p53 mutation; and were considered medically fit. In the first part of the study (induction phase), all participants received eight intravenous infusions of obinutuzumab 1000 mg over six 4-weekly cycles and oral ibrutinib 420 mg once per day for 9 months. In part 2, after assessment on day 1 of month 9, patients with a complete response and bone marrow minimal residual disease of less than 0·01% received only oral ibrutinib 420 mg once per day for 6 additional months. Patients with a partial response, or with a complete response and bone marrow minimal residual disease of 0·01% or more, received 6 months of four 4-weekly cycles of intravenous fludarabine, cyclophosphamide, and obinutuzumab 1000 mg, alongside continuing ibrutinib 420 mg once per day. The primary endpoint was the proportion of patients achieving a complete response with bone marrow minimal residual disease less than 0·01% on day 1 of month 16 assessed by intention to treat (ITT). This trial is registered with ClinicalTrials.gov (number NCT02666898) and is still open for follow-up.

FINDINGS

Between Oct 27, 2015, and May 16, 2017, 135 patients were enrolled. After induction treatment (day 1 of month 9), 130 patients were evaluable, of which ten (8%) achieved a complete response with bone marrow minimal residual disease of less than 0·01% and were assigned to ibrutinib, and 120 (92%) were assigned to ibrutinib plus fludarabine, cyclophosphamide, and obinutuzumab. After minimal residual disease-guided treatment (day 1 of month 16), 84 (62%, 90% CI 55-69) of 135 patients (ITT population) achieved a complete response with bone marrow minimal residual disease of less than 0·01%. The most common haematological adverse event was thrombocytopenia (in 45 [34%] of 133 patients at grade 1-2 in months 1-9 and in 43 [33%] of 130 patients at grade 1-2 in months 9-15). The most common non-haematological adverse events were infusion-related reactions (in 83 [62%] patients at grade 1-2 in months 1-9) and gastrointestinal disorders (in 62 [48%] patients at grades 1 and 2 in months 9-15). 49 serious adverse events occurred, most frequently infections (ten), cardiac events (eight), and haematological events (eight). No treatment-related deaths occurred.

INTERPRETATION

Obinutuzumab and ibrutinib induction therapy followed by a minimal residual disease driven strategy is safe and active in patients with previously untreated chronic lymphocytic leukaemia. With longer follow-up, including assessing the evolution of minimal residual disease, if response is maintained, this strategy could be an option in the first-line setting in patients with chronic lymphocytic leukaemia, although randomised evidence is needed.

FUNDING

Roche, Janssen.