Minimal Residual Disease Status as a Surrogate Endpoint for Progression-free Survival in Newly Diagnosed Multiple Myeloma Studies: A Meta-analysis

Clinical implications of loss of bone marrow minimal residual disease negativity in multiple myeloma

MRD conversion occurs in 39% of MRD⁻ MM patients and reliably predicts future relapse.

MRD conversion within 10 years of diagnosis confers an inferior overall survival and progress-free survival.

Multiple myeloma (MM) patients frequently attain a bone marrow (BM) minimal residual disease (MRD) negativity status in response to treatment. We identified 568 patients who achieved BM MRD negativity following autologous stem cell transplantation (ASCT) and maintenance combination therapy with an immunomodulatory agent and a proteasome inhibitor. BM MRD was evaluated by next-generation flow cytometry (sensitivity of 10⁻⁵ cells) at 3- to 6-month intervals. With a median follow-up of 9.9 years from diagnosis (range, 0.4-30.9), 61% of patients maintained MRD negativity, whereas 39% experienced MRD conversion at a median of 6.3 years (range, 1.4-25). The highest risk of MRD conversion occurred within the first 5 years after treatment and was observed more often in patients with abnormal metaphase cytogenetic abnormalities (95% vs 84%; P = .001). MRD conversion was associated with a high risk of relapse and preceded it by a median of 1.0 years (range, 0-4.9). However, 27% of MRD conversion-positive patients had not yet experienced a clinical relapse, with a median follow-up of 9.3 years (range, 2.2-21.2). Landmark analyses using time from ASCT revealed patients with MRD conversion during the first 3 years had an inferior overall and progression-free survival compared with patients with sustained MRD negativity. MRD conversion correctly predicted relapse in 70%, demonstrating the utility of serial BM MRD assessment to complement standard laboratory and imaging to make informed salvage therapy decisions.

Harmonization of Flow Cytometric Minimal Residual Disease Assessment in Multiple Myeloma in Centers of Polish Myeloma Consortium

Minimal residual disease (MRD) status is now considered as one of the most relevant prognostic factors in multiple myeloma (MM) while MRD negativity became an important endpoint in clinical trials. Here, we report the results of the first study evaluating the reproducibility of high-sensitivity flow cytometry MM MRD assessment in four laboratories in Poland. EuroFlow protocols for instrument setting standardization and sample preparation in MM MRD assessment were implemented in each laboratory. In the inter-laboratory reproducibility study, 12 bone marrow samples from MM patients were distributed and processed in participant laboratories. In the inter-operator concordance study, 13 raw data files from MM MRD measurements were analyzed by five independent operators. The inter-laboratory study showed high 95% overall concordance of results among laboratories. In the inter-operator study, 89% of MRD results reported were concordant, and the highest immunophenotype interpretation differences with regard to expression of CD27, CD45, CD81 were noticed. We confirmed the applicability and feasibility of the EuroFlow protocol as a highly sensitive method of MRD evaluation in MM. Results of our inter-center comparison study demonstrate that the standardization of MM MRD assessment protocols is highly desirable to improve quality and comparability of results within and between different clinical trials.

The 2020 BMT CTN Myeloma Intergroup Workshop on Immune Profiling and Minimal Residual Disease Testing in Multiple Myeloma

The fifth annual Blood and Marrow Transplant Clinical Trials Network Myeloma Intergroup Workshop on Immune Profiling and Minimal Residual Disease Testing in Multiple Myeloma was conducted as one of the American Society of Hematology Annual Meeting Scientific Workshops on Thursday December 3, 2020. This workshop focused on four main topics: (1) integrating minimal residual disease into clinical trial design and practice; (2) the molecular and immunobiology of disease evolution and progression in myeloma; (3) adaptation of next-generation sequencing, next-generation flow cytometry, and cytometry by time of flight techniques; and (4) chimeric antigen receptor T-cell and other cellular therapies for myeloma. In this report, we provide a summary of the workshop presentations and discuss future directions in the field.

Minimal Residual Disease in Multiple Myeloma: Ready for Prime Time?

ABSTRACT

Minimal residual disease (MRD) techniques are essential to identify the small clonal fraction within and outside the bone marrow. In the last years, evidence regarding their prognostic role for the evaluation of the depth of response of current treatment strategies has grown rapidly. Consequently, MRD was incorporated in an increasing number of clinical trials for multiple myeloma patients, also as primary endpoint, and even to guide therapeutic choices. A robust correlation between MRD negativity and survival was established. Yet, several issues regarding MRD evaluation remain to be addressed: from the optimal and more cost-effective techniques for its assessment and its harmonization worldwide to its use in clinical practice to its impact on treatment modulation. This review focuses on the available evidence supporting the use of MRD status for the management of multiple myeloma patients and on open issues that still need an answer.

Prognostic and predictive biomarker developments in multiple myeloma

New approaches to stratify multiple myeloma patients based on prognosis and therapeutic decision-making, or prediction, are needed since patients are currently managed in a similar manner regardless of individual risk factors or disease characteristics. However, despite new and improved biomarkers for determining the prognosis of patients, there is currently insufficient information to utilise biomarkers to intensify, reduce or altogether change treatment, nor to target patient-specific biology in a so-called predictive manner. The ever-increasing number and complexity of drug classes to treat multiple myeloma have improved response rates and so clinically useful biomarkers will need to be relevant in the era of such novel therapies. Therefore, the field of multiple myeloma biomarker development is rapidly progressing, spurred on by new technologies and therapeutic approaches, and underpinned by a deeper understanding of tumour biology with individualised patient management the goal. In this review, we describe the main biomarker categories in multiple myeloma and relate these to diagnostic, prognostic and predictive applications.

Minimal Residual Disease in Multiple Myeloma: Potential for Blood-Based Methods to Monitor Disease

In recent years, the life expectancy of Multiple Myeloma (MM) patients has substantially improved, but this cancer remains incurable with increasing incidence in the developed world. Most MM patients will eventually relapse due to residual drug-resistant cancerous cells that survive treatment, commonly referred to as minimal residual disease (MRD). Methods to improve MRD detection in MM patients are generating considerable interest as a means of monitoring patients' response to treatment. In clinical laboratories, these methods currently require bone marrow aspirates which are invasive and frequently miss detection of localised disease due to the spatial heterogeneity of disease infiltration. By simplifying serial sampling and allowing for the detection of extramedullary disease, a blood-based method could significantly impact treatment duration and intensity and minimise chemotherapy-induced toxicity. This review will describe the current blood-based techniques available to detect MRD in MM and compare their potential to evaluate patient prognosis and drive therapeutic decisions.

Dynamics of minimal residual disease in patients with multiple myeloma on continuous lenalidomide maintenance: a single-arm, single-centre, phase 2 trial

Background Lenalidomide maintenance improves progression-free survival for patients with multiple myeloma, although its optimal duration is unknown. Clearance of minimal residual disease (MRD) in the bone marrow results in superior outcomes, although its attainment or sustainment does not alter clinical decision-making. Studies that have evaluated MRD serially are limited in length. We therefore aimed to evaluate longitudinal changes in MRD-status (dynamics) and their association with progression-free survival in patients with multiple myeloma.

METHODS

In this single-centre, single-arm, phase 2 study, we enrolled patients aged 18 years and older from the Memorial Sloan Kettering Cancer Center (New York, NY, USA) who had newly diagnosed multiple myeloma following unrestricted frontline therapy and an Eastern Cooperative Oncology Group Performance Status of 2 or lower, including patients who started maintenance before study enrolment. All participants received lenalidomide maintenance at 10 mg for 21 days of 28-day cycles until progression or unacceptable toxic effects for up to 5 years on protocol. The primary endpoint was progression-free survival at 60 months per protocol and key secondary endpoints were MRD rates after completion of the 12th, 24th, and 36th cycle of maintenance and the association between progression-free survival and annual measurement of MRD status. MRD was assessed from first-pull bone marrow aspirates at baseline and annually by flow cytometry per International Myeloma Working Group criteria, (limit of detection of at least 1 × 10^-5) up to a maximum of 5 years. Patients who completed at least four cycles of treatment were included in the analysis of the primary endpoint, and patients who had completed at least one dose of treatment on protocol were assessable for secondary endpoints. The study was registered at ClinicalTrials.gov, NCT02538198, and is now closed to accrual.

FINDINGS

Between Sept 8, 2015, and Jan 25, 2019, 108 patients (100 evaluable for the primary endpoint) were enrolled. Median follow-up was 40·7 months (95% CI 38·7-45·0). At 60 months, progression-free survival was 64% (95% CI 52-79). Median progression-free survival was unreached (95% CI unreached-unreached). MRD dynamics were assessed using 340 MRD assessments done over 5 years for 103 evaluable patients. Patients who sustained MRD negativity for 2 years (n=34) had no recorded disease progression at median 19·8 months (95% CI 15·8-22·3) past the 2-year maintenance landmark. By contrast, patients who lost their MRD-negative responses (n=10) were more likely to progress than those with sustained MRD negativity (HR infinite; p<0·0001) and those with persistent MRD positivity (HR 5·88, 95% CI 1·18-33·33; p=0·015) at the 2-year landmark. Haematological and non-haematological serious adverse events occurred in 19 patients (18%). The most common adverse events of grade 3 or worse were decreased lymphocyte count in 48 (44%) patients and decreased neutrophil count in 47 (44%) patients. One death occurred on study due to sepsis and heart failure and was considered unrelated to the study drug.

INTERPRETATION

Serial measurements of MRD allow for dynamic assessment of risk for disease progression. Early intervention should be investigated for patients with loss of MRD negativity. Sustained MRD positivity is not categorically an unfavourable outcome and might portend prolonged stability of low-level disease.

FUNDING

Memorial Sloan Kettering and Celgene.

Future Directions in Maintenance Therapy in Multiple Myeloma

Autologous stem cell transplantation (ASCT) has been a backbone of therapy for newly diagnosed patients with multiple myeloma eligible for high-dose therapy for decades. Survival outcomes have continued to improve over time, in part because of the incorporation of highly effective induction regimens prior to ASCT as well as post-ASCT maintenance therapy. Randomized phase III clinical trials have helped establish lenalidomide maintenance as a standard of care. However, as nearly all patients will eventually experience disease relapse, there continues to be significant interest in developing novel maintenance strategies to improve upon lenalidomide maintenance. In this review, we summarize the available evidence for the use of immunomodulatory drugs, proteasome inhibitors, and monoclonal antibodies as post-ASCT maintenance therapies as well as discuss future directions and unanswered questions in the field.

Immunotherapy in Multiple Myeloma-Time for a Second Major Paradigm Shift

Multiple myeloma (MM) is a genetically heterogenous disease and remains mostly incurable with a small group of patients achieving long-term disease remission. The past decade witnessed enormous efforts to break the circulus vitiosus of tumor-induced immunosuppression and to re-engage the immune system to fight cancer. The first-in-class anti-CD38 monoclonal antibody, daratumumab, has shown unprecedented responses especially in combination with other novel agents in both newly diagnosed and relapsed MM. There has been great interest in harnessing the power of T cells with bispecific antibodies and chimeric antigen receptor T-cell therapies in hematologic malignancies including MM. These immune-based approaches have shown notable antimyeloma effects with deeper, durable responses in early clinical trials of heavily pretreated patients with MM with limited therapeutic options. Several trials are underway investigating both single and combinatorial immune therapies at different stages with a hope to bring major transformation in MM. In the current review, we summarize how an immunologic approach offers promise for the treatment of MM and is setting the stage for second major paradigm shift 2 decades after the emergence of thalidomide and novel therapeutics.

Measurable residual disease as a biomarker in acute myeloid leukemia: theoretical and practical considerations

Several methodologies that rely on the detection of immunophenotypic or molecular abnormalities of the neoplastic cells are now available to quantify measurable ("minimal") residual disease (MRD) in acute myeloid leukemia (AML). Although the perfect MRD test does not (yet) exist, the strong association between MRD and adverse patient outcomes has provided the impetus to use measures of MRD as biomarker in the routine care of AML patients and during clinical trials. MRD test results may inform the selection of postremission therapy in some patients but evidence supporting the use of MRD as predictive biomarker is still limited. Several retrospective studies have shown that conversion from undetectable to detectable MRD or increasing MRD over time is associated with overt disease recurrence, and MRD testing may therefore be valuable as a monitoring biomarker for early detection of relapse. Interpreting serial MRD data is complex, with open questions regarding the optimal timing and frequency of testing, as well as the identification of test-specific thresholds to define relapse. Importantly, it is unknown whether intervening at the time of MRD detection, rather than at overt disease recurrence, improves outcomes. Finally, using MRD as a surrogate efficacy-response biomarker to accelerate drug development/approval has already been accepted by regulatory authorities in other diseases and is of great interest as a potential strategy in AML. While the prognostic value of MRD in AML is well established, data from prospective clinical trials confirming that treatment effects on MRD directly relate to clinical outcomes are needed to further establish the role of MRD as a surrogate endpoint in AML.

Multiple Myeloma: Heterogeneous in Every Way

Simple Summary

With the development of modern therapies in multiple myeloma, prognosis stratification is becoming an indispensable tool for the choice of treatment between patients. Many factors influence the prognosis in multiple myeloma; scores, mainly based on biochemical parameters and cytogenetics, have been proposed to discriminate patients. However, these scores are not perfect and fail to predict some patients’ outcomes. In this review, we describe current evaluated factors and their limitations. In the second part, we address factors with an impact on treatment escape and prognosis, but which are not available routinely yet.

Abstract

Multiple myeloma (MM) is a hematological malignancy characterized by the accumulation of tumor plasma cells (PCs) in the bone marrow (BM). Despite considerable advances in terms of treatment, patients’ prognosis is still very heterogeneous. Cytogenetics and minimal residual disease both have a major impact on prognosis. However, they do not explain all the heterogeneity seen in the outcomes. Their limitations are the result of the emergence of minor subclones missed at diagnosis, detected by sensible methods such as single-cell analysis, but also the non-exploration in the routine practice of the spatial heterogeneity between different clones according to the focal lesions. Moreover, biochemical parameters and cytogenetics do not reflect the whole complexity of MM. Gene expression is influenced by a tight collaboration between cytogenetic events and epigenetic regulation. The microenvironment also has an important impact on the development and the progression of the disease. Some of these determinants have been described as independent prognostic factors and could be used to more accurately predict patient prognosis and response to treatment.

Minimal residual disease in multiple myeloma: defining the role of next generation sequencing and flow cytometry in routine diagnostic use

For patients diagnosed with multiple myeloma (MM) there have been significant treatment advances over the past decade, reflected in an increasing proportion of patients achieving durable remissions. Clinical trials repeatedly demonstrate that achieving a deep response to therapy, with a bone marrow assessment proving negative for minimal residual disease (MRD), confers a significant survival advantage. To accurately assess for minute quantities of residual cancer requires highly sensitive methods; either multiparameter flow cytometry or next generation sequencing are currently recommended for MM response assessment. Under optimal conditions, these methods can detect one aberrant cell amongst 1,000,000 normal cells (a sensitivity of 10^-6). Here, we will review the practical use of MRD assays in MM, including challenges in implementation for the routine diagnostic laboratory, standardisation across laboratories and clinical trials, the clinical integration of MRD status assessment into MM management and future directions for ongoing research.

First reported case of secondary mixed phenotype acute leukemia after multiple myeloma

In recent years the outcome of patients with multiple myeloma (MM) has significantly improved, due to new drugs. However, some agents, i.e. the alkylating drug melphalan, can be associated with an increased incidence of secondary malignancies. Myelodysplastic syndromes and acute myeloid leukemia are reported in the literature, and rarely acute lymphoblastic leukemia. Here we describe a unique case of a 56-years old female patient affected by MM since 2015 in complete remission after autologous stem cell transplant and in lenalidomide maintenance, who developed 2 years later mixed phenotype acute leukemia (MPAL). The patient, refractory to both lymphoblastic and myeloid acute leukemia regimens, achieved complete remission with bi-specific anti-CD19/anti-CD3 monoclonal antibody blinatumomab and with hypomethylating agent azacytidine plus the BCL-2 inhibitor venetoclax. She then underwent hematopoietic stem cell transplantation from HLA-identical sibling donor and she is still in complete remission after 9 months. To the best of our knowledge, there are no cases in the literature describing MPAL after autologous transplant for MM. Our patient was treated with blinatumomab and venetoclax and achieved complete remission 9 months from allogeneic transplant. The mechanism underlying the development of MPAL is not completely understood and therapies are still lacking. In this context the combination of blinatumomab, azacytidine and venetoclax successfully used in this patient may provide food for thought for further studies in this rare setting of patients.

Autologous Transplantation Using Donor Leukocytes Loaded Ex Vivo with Oncolytic Myxoma Virus Can Eliminate Residual Multiple Myeloma

Multiple myeloma (MM) is a hematological malignancy of monoclonal plasma cells that remains incurable. Standard treatments for MM include myeloablative regimens and autologous cell transplantation for eligible patients. A major challenge of these treatments is the relapse of the disease due to residual MM in niches that become refractory to treatments. Therefore, novel therapies are needed in order to eliminate minimal residual disease (MRD). Recently, our laboratory reported that virotherapy with oncolytic myxoma virus (MYXV) improved MM-free survival in an allogeneic transplant mouse model. In this study, we demonstrate the capacity of donor autologous murine leukocytes, pre-armed with MYXV, to eliminate MRD in a BALB/c MM model. We report that MYXV-armed bone marrow (BM) carrier leukocytes are therapeutically superior to MYXV-armed peripheral blood mononuclear cells (PBMCs) or free virus. Importantly, when cured survivor mice were re-challenged with fresh myeloma cells, they developed immunity to the same MM that had comprised MRD. In vivo imaging demonstrated that autologous carrier cells armed with MYXV were very efficient at delivery of MYXV into the recipient tumor microenvironment. Finally, we demonstrate that treatment with MYXV activates the secretion of pro-immune molecules from the tumor bed. These results highlight the utility of exploiting autologous leukocytes to enhance tumor delivery of MYXV to treat MRD in vivo.

Minimal Residual Disease in Multiple Myeloma: State of the Art and Applications in Clinical Practice

Novel drugs have revolutionized multiple myeloma therapy in the last 20 years, with median survival that has doubled to up to 8–10 years. The introduction of therapeutic strategies, such as consolidation and maintenance after autologous stem cell transplants, has also ameliorated clinical results. The goal of modern therapies is becoming not only complete remission, but also the deepest possible remission. In this context, the evaluation of minimal residual disease by techniques such as next-generation sequencing (NGS) and next-generation flow (NGF) is becoming part of all new clinical trials that test drug efficacy. This review focuses on minimal residual disease approaches in clinical trials, with particular attention to real-world practices.

Practical considerations of utilizing propensity score methods in clinical development using real-world and historical data

In recent years, with the rapid increase in the volume and accessibility of Real-World-Data (RWD) and Real-World-Evidence (RWE), we have seen the unprecedented opportunities for their use in drug clinical development and life-cycle management. RWD and RWE have demonstrated the significant potential to improve the design, planning, and execution of clinical development. Furthermore, they can feature in the designs as either a substitute or compliment to traditional clinical trials. However, to utilize RWD and RWE appropriately and wisely, it is critical to apply rigorous statistical methodologies that enable the robustness of results to be characterized and ascertained. Several statistical methodologies including exact matching, propensity score methods, matching-adjusted indirect comparisons and meta-analysis have been proposed for analyzing RWD. Among them, propensity score method is one of the most commonly used methods for non-randomized trials with indirect comparison. Although massive methodologies and examples have been published and discussed since propensity score methods were introduced, systematic review and discussion of how to rigorously use propensity score methods in the practical clinical development is still deficient. This paper introduces commonly used and emerging propensity score methods with detailed discussions of their pros and cons. Three different case studies are presented to illustrate the practical considerations of utilizing propensity score methods in the study design and evaluation using real-world and historical data. Additional considerations including selection of patient populations, endpoints, baseline covariates, propensity score methods, sensitivity analysis and practical implementation flow in clinical development will be discussed.

Minimal Residual Disease in Multiple Myeloma: State of the Art and Future Perspectives

Minimal residual disease (MRD) detection represents a sensitive tool to appropriately measure the response obtained with therapies for multiple myeloma (MM). The achievement of MRD negativity has superseded the conventional complete response (CR) and has been proposed as a surrogate endpoint for progression-free survival and overall survival. Several techniques are available for the detection of MRD inside (next-generation sequencing, flow cytometry) and outside (PET/CT, magnetic resonance) the bone marrow, and their complementary use allows a precise definition of the efficacy of anti-myeloma treatments. This review summarizes MRD data and results from previous clinical trials, highlights open issues related to the role of MRD in MM and discusses how MRD could be implemented in clinical practice to inform on patient prognosis and drive therapeutic decisions.

Cell-free DNA for genomic profiling and minimal residual disease monitoring in Myeloma- are we there yet?

OBJECTIVE

Multiple myeloma (MM), a plasma cell neoplasm, afflicts elder individuals accounting for 10% of hematologic malignancies. The MM plasma cells largely reside within the bone marrow niche and are accessible through an invasive bone marrow biopsy, which is challenging during serial monitoring of patients. In this setting, cell free DNA (cfDNA) may have a role to ascertain the molecular aberrations at diagnosis and in assessment of residual disease during therapy. The aim of this review was to explore the utility and current status of cfDNA in MM.

METHOD

PubMed was searched with terms including cell-free DNA, circulating-tumor DNA, Multiple Myeloma, diagnosis, genomic profiling, Minimal Residual Disease individually or in combination to shortlist the relevant studies.

RESULT

cfDNA serves as a non-invasive source of tumor-specific molecular biomarker, ctDNA that has immense potential in facilitating management of cancer patients. The mutation detection platforms for ctDNA include hybrid capture and ultra-deep sequencing. Hybrid capture allows full length gene sequencing for mutation and CNV detection. The disease progression can be monitored by profiling prognostic somatic copy number alterations by ultra-low pass whole genome sequencing of ctDNA cost-effectively. Evolution of both the laboratory protocols and bioinformatics tools may further improve the sensitivity of ctDNA detection for better disease management. Only a limited number of studies were available in MM exploring the potential utility of cfDNA.

CONCLUSION

In this review, we discuss the nuances and challenges associated with molecular evaluation of cfDNA and its potential role in diagnosis and monitoring of treatment response in MM.

Minimal Residual Disease in Multiple Myeloma: Current Landscape and Future Applications With Immunotherapeutic Approaches

The basic principle that deeper therapeutic responses lead to better clinical outcomes in cancer has emerged technologies capable of detecting rare residual tumor cells. The need for ultra-sensitive approaches for minimal residual disease (MRD) detection is particularly evident in Multiple Myeloma (MM), where patients will ultimately relapse despite the achievement of complete remission, which is commonplace due to remarkable therapeutic advances. Consequently, current response criteria on MM have been amended based on MRD status and MRD negativity is now considered the most dominant prognostic factor and the most valuable indicator for a subsequent relapse. However, there are particular limitations and several aspects for MRD assessment that remain open. This review summarizes current data on MRD in the clinical management of MM, highlights open issues and discusses the challenges and the endless opportunities arising for both patients and clinicians. Furthermore, it focuses on the current status of MRD in clinical trials, its dynamics in addressing debatable aspects in the clinical handling and its potential role as the prevailing factor for future MRD-driven tailored therapies.

Monitoring minimal residual disease in the bone marrow using next generation sequencing

Achieving minimal residual disease (MRD) negativity in the bone marrow is one of the strongest prognostic factors in multiple myeloma. Consequently, MRD testing is routinely performed in clinical trials and moving towards standard of care. This review focuses on the role of next generation sequencing (NGS) of tumor-specific immunoglobulin V(D)J sequences for MRD tracking. The immunoglobulin variable regions are ideal targets for tracking, because every tumor cell shares an identical gene sequence, which is stable over time and generally distinct from the immunoglobulin sequences of normal B-cells. Several excellent assays for NGS-based MRD testing are available, both commercial and community-based, including one that is FDA-approved. These assays can achieve the gold standard analytical sensitivity of one tumor cell per million (10^-6), requiring a minimum input of 3 million bone marrow cells. On-going clinical trials will outline how MRD testing should be used to inform dynamic risk-adopted therapy.