Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)

The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer-reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state-of-the-art handbook for basic and clinical researchers.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition)

These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.

Cell-based immunotherapy approaches for multiple myeloma

Despite the arrival of novel therapies, multiple myeloma (MM) remains incurable and new treatment options are needed. Chimeric antigen receptor (CAR) T cells are genetically modified T cells that express a CAR directed against specific tumour antigens. CAR T cells are able to kill target tumour cells and may result in long-lasting immune responses in vivo. The rapid development of CAR technologies has led to clinical trials in haematological cancers including MM, and CAR T cells might evolve into a standard treatment in the next few years. Only small patient cohorts with relapsed or refractory disease have so far been investigated, but promising preliminary results with high response rates have been  obtained in phase I clinical trials with B cell maturation antigen (BCMA), CD19, CD38 and κ-light-chain CAR T cells. Additional preclinical studies on CD38 and SLAMF7-CAR T cells in MM treatment yielded preclinical results that merit further investigation. Beyond the T cell approach, recent studies have focussed on CAR natural killer (NK) cells in order to increase the reactivity of these effector cells. Finally, to investigate the targeting of intracellular antigens, cellular therapies based on engineered T cell receptors (TCRs) are in development. In this review, we discuss results from preclinical and early-phase clinical trials testing the feasibility and safety of CAR T cell administration in MM, as well as early studies into approaches that utilise CAR NK cell and genetically modified TCRs.

Quantification of number of CD38 sites on bone marrow plasma cells in patients with light chain amyloidosis and smoldering multiple myeloma

BACKGROUND

Recent approaches in multiple myeloma (MM) treatment have targeted CD38. As antigen expression levels on plasma cells (PCs) were demonstrated to affect response to monoclonal antibody (mAb) treatment, a precise characterization of PC phenotype is warranted.

METHODS

Anti-CD38 mAb (isatuximab) was tested for antibody-dependent cellular cytotoxicity (ADCC) in MM cell lines. Quantification of the number of sites (NOS) of CD38 on bone marrow PCs and other immune cells obtained from light chain (AL) amyloidosis (n = 46) and smoldering multiple myeloma (SMM) patients (n = 19) was performed with two different quantitative flow cytometry (QFCM) applications.

RESULTS

ADCC activity of isatuximab was observed in cell lines with >100 × 10³ CD38-NOS only. The average PC CD38-NOS was 153 ± 53 × 10³ in AL amyloidosis and 138.7 ± 53 × 10³ in SMM patients. Eight (17%) AL amyloidosis and 4 (21%) SMM patients showed a PC CD38-NOS level <100 × 10³ . In four AL amyloidosis and two SMM patients <10% of PCs had a CD38-NOS ≥100 × 10³ . The CD38-NOS identified on bone marrow lymphocytes, monocytes, and granulocytes was two log units below the CD38-NOS on PCs (P < 0.001). No significant differences in CD38-NOS expression levels on any of the analyzed PC subpopulations in AL amyloidosis and SMM patients were identified.

CONCLUSION

Levels of CD38 expression affect the isatuximab-mediated ADCC in vitro. As PCs of patients with AL amyloidosis and SMM do not homogenously express high CD38 our data provide a rationale for assessment of CD38-NOS in patients with PC disorders prior to anti-CD38 treatment. © 2018 International Clinical Cytometry Society.

Emerging drugs and combinations to treat multiple myeloma

In the past few years, multiple targeted therapies and immunotherapies including second generation immunomodulatory drugs (pomalidomide) and proteasome inhibitors (carfilzomib, ixazomib), monoclonal antibodies and checkpoint inhibitors were approved for the treatment of myeloma or entered advanced phases of clinical testing. These agents showed significant activity in advanced myeloma and increased the available treatment strategies. Pomalidomide is well-tolerated and effective in patients with relapsed/refractory multiple myeloma who have exhausted any possible treatment with lenalidomide and bortezomib. Carfilzomib, a second-generation proteasome inhibitor, is active as a single agent and in combination with other anti-myeloma agents. Ixazomib is the first oral proteasome inhibitor to be evaluated in myeloma and is associated with a good safety profile and anti-myeloma activity in relapsed/refractory patients, even in those refractory to bortezomib. Monoclonal antibodies and immune checkpoint inhibitors are likely to play a major role in the treatment of myeloma over the next decade. In phase 3 studies, triplet regimens based on these agents combined with a backbone therapy (including lenalidomide, pomalidomide or bortezomib) were more efficacious than doublet regimens in patients with relapsed/refractory multiple myeloma, with limited additional toxic effects. This paper aims to provide an overview of the recent use of these agents for the treatment of myeloma, in particular focusing on the role of multi-agent combinations.

CD38 expression and complement inhibitors affect response and resistance to daratumumab therapy in myeloma

Response to the CD38-targeting antibody daratumumab is significantly associated with CD38 expression levels on the tumor cells. Resistance to daratumumab is accompanied by increased expression of complement-inhibitory proteins.

Evolving Paradigms in the Management of Multiple Myeloma: Novel Agents and Targeted Therapies

Multiple myeloma (MM) is a clonal plasma cell disorder defined by bone marrow infiltration and osteolytic bone lesions and is the second most common hematologic malignancy after non-Hodgkin lymphoma. The landscape of MM treatment was transformed at the dawn of the twenty-first century by the introduction of novel agents including proteasome inhibitors (bortezomib) and immunomodulatory drugs (thalidomide, lenalidomide), which have prolonged the survival of MM patients. The recently revised International Myeloma Working Group diagnostic criteria for MM added validated biomarkers (clonal bone marrow plasma cell ≥60%, involved:uninvolved serum free light chain ratio ≥100, or >1 focal lesion on magnetic resonance imaging) to identify near inevitable progression to symptomatic MM requiring therapy. In addition, the definition of myeloma-defining CRAB features (hypercalcemia, renal failure, anemia, and bone lesions) has been refined based on advances in imaging and laboratory techniques since the 2003 IMWG consensus. Despite expanded treatment options, MM remains an incurable disease. Drug resistance and clonal evolution remain problematic, and novel therapeutic agents are needed. New approaches to myeloma treatment include anti-CD38 antibodies, next generation proteasome inhibitors, epigenetic modulation with histone deacetylase inhibitors, and targeting the tumor microenvironment. In this article, the diagnosis, staging, and prognostic stratification of newly diagnosed MM will be reviewed. Clinical data pertaining to the emerging targeted agents will be discussed, and a suggested framework for integration of these new therapeutic options will be provided.

Monoclonal antibodies in the treatment of multiple myeloma: current status and future perspectives

The treatment landscape for patients with multiple myeloma (MM) is constantly evolving. Over the past decade, the introduction of novel agents such as proteasome inhibitors and immunomodulatory drugs has led to notable changes in therapeutic strategy, and improvements in survival, yet MM remains incurable in the vast majority of cases. More recently, a targeted approach to MM treatment has emerged, using monoclonal antibodies (mAbs) to target antigens expressed on the surface of MM cells. MAbs tested to date kill MM cells via the host's immune system and/or by promoting apoptosis, and appear to have generally improved tolerability compared with currently available treatments. Due to their distinct mode of action, mAbs are promising both for patients who have exhausted current regimens, and as part of first-line treatments in newly diagnosed patients. This review examines the recent developments in mAb-based therapy for MM, primarily focused on those agents in ongoing clinical testing.

CD38 Monoclonal Antibody Therapies for Multiple Myeloma

The goal of this review is to provide historical, recent preclinical, and current clinical summaries of efforts to understand the CD38 molecule and to develop monoclonal antibodies that target it. We focus particularly on efforts involving multiple myeloma, a malignancy of terminally differentiated B cells that remains incurable despite many advances. An era of anti-CD38 monoclonal antibody therapy for myeloma is approaching, one that, we hope, will enable patients to live longer and better lives.

Daratumumab and its potential in the treatment of multiple myeloma: overview of the preclinical and clinical development

Despite the recent major advancement in therapy for multiple myeloma, it remains an incurable disease. There remains an unmet need for novel therapies that target different mechanisms of action. Immunotherapy with monoclonal antibodies is a promising area of development and will expand our therapeutic armamentarium in the fight against myeloma. Daratumumab is a novel, high-affinity, therapeutic human monoclonal antibody against unique CD38 epitope with broad-spectrum killing activity. It has a favorable safety profile as monotherapy in patients with relapsed/refractory myeloma and also demonstrates significant single-agent activity. Abundant preclinical data supports its use in combination therapy and clinical studies on various exciting combinations are underway. This review focuses on the CD38 antigen and its targeting with daratumumab and provides an update on the results of recent clinical studies involving daratumumab.

Upregulation of CD38 expression on multiple myeloma cells by all-trans retinoic acid improves the efficacy of daratumumab

Daratumumab is an anti-CD38 monoclonal antibody with lytic activity against multiple myeloma (MM) cells, including ADCC (antibody-dependent cellular cytotoxicity) and CDC (complement-dependent cytotoxicity). Owing to a marked heterogeneity of response to daratumumab therapy in MM, we investigated determinants of the sensitivity of MM cells toward daratumumab-mediated ADCC and CDC. In bone marrow samples from 144 MM patients, we observed no difference in daratumumab-mediated lysis between newly diagnosed or relapsed/refractory patients. However, we discovered, next to an expected effect of effector (natural killer cells/monocytes) to target (MM cells) ratio on ADCC, a significant association between CD38 expression and daratumumab-mediated ADCC (127 patients), as well as CDC (56 patients). Similarly, experiments with isogenic MM cell lines expressing different levels of CD38 revealed that the level of CD38 expression is an important determinant of daratumumab-mediated ADCC and CDC. Importantly, all-trans retinoic acid (ATRA) increased CD38 expression levels but also reduced expression of the complement-inhibitory proteins CD55 and CD59 in both cell lines and primary MM samples. This resulted in a significant enhancement of the activity of daratumumab in vitro and in a humanized MM mouse model as well. Our results provide the preclinical rationale for further evaluation of daratumumab combined with ATRA in MM patients.

Early or delayed transplantation for multiple myeloma in the era of novel therapy: does one size fit all?

For the last 20 years, high-dose therapy with autologous stem cell transplantation (ASCT) for multiple myeloma has been considered a standard frontline treatment for younger patients with adequate organ function. With the introduction of novel agents, specifically thalidomide, bortezomib, and lenalidomide, the role of ASCT has changed in several ways. First, novel agents have been incorporated successfully as induction regimens, increasing the response rate before ASCT, and are now being used as part of both consolidation and maintenance with the goal of extending progression-free and overall survival. These approaches have shown considerable promise with significant improvements in outcome. Furthermore, the efficacy of novel therapeutics has also led to the investigation of these agents upfront without the immediate application of ASCT, and compelling preliminary results have been reported. Next-generation novel agents and the use of monoclonal antibodies have raised the possibility of not only successful salvage strategies to facilitate delayed transplantation for younger patients, but also the prospect of an nontransplantation approach achieving the same outcome. Moreover, this could be achieved without incurring acute toxicity or long-term complications that are inherent to high-dose alkylation, and melphalan exposure in particular. At present, the role of ASCT has therefore become an area of debate: should it be used upfront in all eligible patients, or should it be used as a salvage treatment at the time of progression for patients achieving a high quality of response with initial therapy? There is a clear need to derive a consensus that is useful for clinicians considering both protocol-directed and non-protocol-directed options for their patients. Participation in ongoing prospective randomized trials is considered vital. While preliminary randomized data from studies in Europe favor early ASCT with novel agents, differences in both agents and the combinations used, as well as limited information on overall survival and benefit for specific patient subsets, suggest that one size does not fit all. Specifically, the optimal approach to treatment of younger patients eligible for ASCT remains a key area for further research. A rigid approach to its use outside of a clinical study is difficult to justify and participation in prospective studies should be a priority.

Early or delayed transplantation for multiple myeloma in the era of novel therapy: does one size fit all?

For the last 20 years, high-dose therapy with autologous stem cell transplantation (ASCT) for multiple myeloma has been considered a standard frontline treatment for younger patients with adequate organ function. With the introduction of novel agents, specifically thalidomide, bortezomib, and lenalidomide, the role of ASCT has changed in several ways. First, novel agents have been incorporated successfully as induction regimens, increasing the response rate before ASCT, and are now being used as part of both consolidation and maintenance with the goal of extending progression-free and overall survival. These approaches have shown considerable promise with significant improvements in outcome. Furthermore, the efficacy of novel therapeutics has also led to the investigation of these agents upfront without the immediate application of ASCT, and compelling preliminary results have been reported. Next-generation novel agents and the use of monoclonal antibodies have raised the possibility of not only successful salvage strategies to facilitate delayed transplantation for younger patients, but also the prospect of an nontransplantation approach achieving the same outcome. Moreover, this could be achieved without incurring acute toxicity or long-term complications that are inherent to high-dose alkylation, and melphalan exposure in particular. At present, the role of ASCT has therefore become an area of debate: should it be used upfront in all eligible patients, or should it be used as a salvage treatment at the time of progression for patients achieving a high quality of response with initial therapy? There is a clear need to derive a consensus that is useful for clinicians considering both protocol-directed and non-protocol-directed options for their patients. Participation in ongoing prospective randomized trials is considered vital. While preliminary randomized data from studies in Europe favor early ASCT with novel agents, differences in both agents and the combinations used, as well as limited information on overall survival and benefit for specific patient subsets, suggest that one size does not fit all. Specifically, the optimal approach to treatment of younger patients eligible for ASCT remains a key area for further research. A rigid approach to its use outside of a clinical study is difficult to justify and participation in prospective studies should be a priority.