Flow cytometric detection of aneuploid CD38(++) plasmacells and CD19(+) B-lymphocytes in bone marrow, peripheral blood and PBSC harvest in multiple myeloma patients

Daratumumab for autoimmune diseases: a systematic review

OBJECTIVE

Refractory autoimmune diseases remain a significant challenge in clinical practice and new therapeutic options are needed. This systematic review evaluates the existing reported data on the CD38-targeting antibody daratumumab as a new therapeutic approach in autoantibody-mediated autoimmune diseases.

METHODS

A protocolised systematic literature review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed. Two databases (Medline and Embase) were searched for suitable studies. Usage of daratumumab in non-oncological or non-transplantation associated diseases with autoimmune pathophysiology was analysed including patient characteristics, therapeutic regimen, adverse events and patient outcome.

RESULTS

38 publications reporting the clinical course of 83 patients met the inclusion criteria. Daratumumab usage was reported in therapy-refractory cases (median of 5 different previous therapies) in 24 different autoimmune diseases. The median number of applications of daratumumab was 4, mainly via intravenous applications (87%). Concomitant treatment included glucocorticoids in 64% of patients, intravenous immunoglobulins (33%) and rituximab (17%). Remission or improvement of disease was reported in 81% of patients. Autoantibody depletion or reduction was stated in 52% of patients. Death occurred in three patients (3%). Adverse events were reported in 45% of patients including application-associated reaction (20%), infection (19%) and hypogammaglobulinaemia (33%).

CONCLUSION

Targeting CD38 via daratumumab is a new promising therapeutic option in therapy refractory autoimmune diseases. Efficacy as well as optimal therapeutic regimen and management or prevention of adverse events require further investigation. Therefore, systematic clinical trials of this therapeutic approach are needed.

Good Cop, Bad Cop: Profiling the Immune Landscape in Multiple Myeloma

Multiple myeloma (MM) is a dyscrasia of plasma cells (PCs) characterized by abnormal immunoglobulin (Ig) production. The disease remains incurable due to a multitude of mutations and structural abnormalities in MM cells, coupled with a favorable microenvironment and immune suppression that eventually contribute to the development of drug resistance. The bone marrow microenvironment (BMME) is composed of a cellular component comprising stromal cells, endothelial cells, osteoclasts, osteoblasts, and immune cells, and a non-cellular component made of the extracellular matrix (ECM) and the liquid milieu, which contains cytokines, growth factors, and chemokines. The bone marrow stromal cells (BMSCs) are involved in the adhesion of MM cells, promote the growth, proliferation, invasion, and drug resistance of MM cells, and are also crucial in angiogenesis and the formation of lytic bone lesions. Classical immunophenotyping in combination with advanced immune profiling using single-cell sequencing technologies has enabled immune cell-specific gene expression analysis in MM to further elucidate the roles of specific immune cell fractions from peripheral blood and bone marrow (BM) in myelomagenesis and progression, immune evasion and exhaustion mechanisms, and development of drug resistance and relapse. The review describes the role of BMME components in MM development and ongoing clinical trials using immunotherapeutic approaches.

[A case of progressive multifocal leukoencephalopathy associated with daratumumab, bortezomib, and dexamethasone for multiple myeloma]

An 83-year-old man presented with visual disturbance and right hemiparalysis, one month after daratumumab, bortezomib, and dexamethasone administration for multiple myeloma (MM). Blood screens revealed a CD4+ T-lymphocyte count of 132/μl. Diffusion weighted and fluid-attenuated inversion-recovery MR imaging showed high intensity signals in the both occipital lobes and left precentral area. The patient had no history of human immunodeficiency virus infection. Cerebrospinal fluid (CSF) JC virus (JCV) was positive (83 copies/ml), as indicated by PCR. The patient was diagnosed with progressive multifocal leukoencephalopathy (PML). MM treatment was discontinued, and mefloquine and mirtazapine therapy was started. However, the CSF JCV-DNA PCR count did not improve (111 copies/ml) after 30 days from starting mefloquine and mirtazapine therapy. The patient died six months after symptom onset. Conclusively, patients with decreased CD4+ T lymphocyte counts following DBd therapy for MM, the possibility of PML should be considered.

Cumulative Incidence and Relative Risk of Infection in Patients With Multiple Myeloma Treated With Anti-CD38 Monoclonal Antibody-Based Regimens: A Systematic Review and Meta-analysis

BACKGROUND

Patients with multiple myeloma are at higher risk for infections due to disease pathogenesis and administered therapies. The purpose of this study was to estimate the risk for any grade and severe infections associated with the use of anti-CD38 monoclonal antibodies in patients with multiple myeloma.

METHODS

We searched PubMed and EMBASE for randomized controlled trials (RCTs) that included patients with multiple myeloma who received CD38-targeting monoclonal antibody regimens and reported outcomes of infection and performed a random-effects meta-analysis to estimate the relative risk for infections.

RESULTS

After screening 673 citations, we retrieved 17 studies providing data on 11 RCTs. Overall, the included reports evaluated 5316 patients (2797 in the intervention arm and 2519 in the control arm). The relative risk (RR) for both any grade or severe infections was 1.27 (95% CI, 1.17-1.37 and 1.14-1.41, respectively). The cumulative incidence of any grade infections for patients who received anti-CD38 agents was 77% (95% CI, 68%-86%), while for severe infections it was 28% (95% CI, 23%-34%). Patients treated with anti-CD38 agents had a 39% higher risk for any grade pneumonia (RR, 1.39; 95% CI, 1.12-1.72) and a 38% higher risk for severe pneumonia (RR, 1.38; 95% CI, 1.09-1.75). For upper respiratory tract infections, the relative risk was 1.51 and 1.71 for any grade and severe infections, respectively. Regarding varicella-zoster virus (VZV) reactivation, we found no evidence of increased risk (RR, 3.86; 95% CI, 0.66-22.50).

CONCLUSIONS

Patients with multiple myeloma treated with regimens that included an anti-CD38 monoclonal antibody were at higher risk for any grade or severe infections without an associated higher mortality rate during the follow-up period of the retrieved studies. No evidence of increased risk for VZV reactivation was noted, but there was a significant association between CD38-targeting treatment and pneumonia risk. Increased surveillance for infections, development of effective prophylactic strategies, and studies with long follow-up are needed for patients with multiple myeloma treated with anti-CD38-based regimens.

Efficacy and mechanism of the anti-CD38 monoclonal antibody Daratumumab against primary effusion lymphoma

Primary effusion lymphoma (PEL) is a rare, aggressive B cell non-Hodgkin's lymphoma of the body cavities with malignant effusions. The prognosis is poor, and no optimal treatment has been established. CD38 is a type II transmembrane glycoprotein known to overexpress in multiple myeloma (MM). Daratumumab (DARA), a human CD38-targeting monoclonal antibody (mAb), is approved for MM treatment. In this study, we found expression of CD38 on PEL cells and assessed the anti-PEL activity of DARA. We found that both KHYG-1 and N6 (CD16-transfected KHYG-1) NK cell lines showed direct killing activity against PEL cells with induction of CD107a, and NK-mediated cytotoxicity by N6NK (CD16+) cells increased with DARA treatment. We confirmed direct NK activity and antibody-dependent cell cytotoxicity (ADCC) by expanded NK cells, indicating that DARA has high ADCC activity. We elucidated the antibody-dependent cell phagocytosis (ADCP) by using human monocyte-derived macrophages (MDMs) and mouse peritoneal macrophages. DARA also showed potent complement-dependent cytolysis (CDC) toward PEL. DARA also induced PEL cell death in the presence of a cross-linking antibody. Moreover, treatment with DARA inhibited tumor growth in a PEL xenograft mouse model. These results provide preclinical evidence that Ab targeting of CD38 could be an effective therapeutic strategy for the treatment of PEL.

Daratumumab combined with dexamethasone and lenalidomide or bortezomib in relapsed/refractory multiple myeloma (RRMM) patients: Report from the multiple myeloma GIMEMA Lazio group

The multiple myeloma (MM) treatment has changed over the last years due to the introduction of novel drugs. Despite improvements in the MM outcome, MM remains an incurable disease. Daratumumab is a human IgGK monoclonal antibody targeting CD38 with tumor activity associated with immunomodulatory mechanism. In combination with standard of care regimens, including bortezomib (Vd) or lenalidomide (Rd), daratumumab prolonged progression-free survival (PFS) in patients (pts) with relapsed/refractory multiple myeloma (RRMM) and in new diagnosis MM. We report the data of the MM GIMEMA Lazio group in 171 heavily treated pts who received daratumumab, lenalidomide and dexamethasone (DRd) or daratumumab, velcade and dexamethasone (DVd). The overall response rate was 80%, and the overall survival (OS) and PFS were 84% and 77%, respectively. In addition, pts treated with DRd showed a better median PFS compared to pts treated with DVd, at 12 and 24 months, respectively. The most common hematologic treatment-emergent adverse events (TAEs) were neutropenia, thrombocytopenia, and anemia. The most common nonhematologic TAEs were peripheral sensory neuropathy and infections. Our data confirmed that DRd or DVd therapy is effective and safe in RRMM pts, and our real-life analysis could support the physicians regarding the choice of optimal therapy in this setting of pts.

Emerging New Approaches in Desensitization: Targeted Therapies for HLA Sensitization

There is an urgent need for therapeutic interventions for desensitization and antibody-mediated rejection (AMR) in sensitized patients with preformed or de novo donor-specific HLA antibodies (DSA). The risk of AMR and allograft loss in sensitized patients is increased due to preformed DSA detected at time of transplant or the reactivation of HLA memory after transplantation, causing acute and chronic AMR. Alternatively, de novo DSA that develops post-transplant due to inadequate immunosuppression and again may lead to acute and chronic AMR or even allograft loss. Circulating antibody, the final product of the humoral immune response, has been the primary target of desensitization and AMR treatment. However, in many cases these protocols fail to achieve efficient removal of all DSA and long-term outcomes of patients with persistent DSA are far worse when compared to non-sensitized patients. We believe that targeting multiple components of humoral immunity will lead to improved outcomes for such patients. In this review, we will briefly discuss conventional desensitization methods targeting antibody or B cell removal and then present a mechanistically designed desensitization regimen targeting plasma cells and the humoral response.

Role of Daratumumab in Combination With Standard Therapies in Patients With Relapsed and Refractory Multiple Myeloma

Multiple myeloma (MM) is a hematological malignancy characterized by renal insufficiency, bone lesions, anemia, and hypercalcemia. In this modern era of medicine, even with the development of drugs like immunomodulatory agents (IMiDs) and proteasome inhibitors (PI), the treatment of MM prevails as a challenge. However, even after the attainment of total remission, relapse of MM and disease progression is frequent. That is why there is an urgent requirement to develop novel monoclonal antibody drugs. The latest drugs for the treatment of relapsed and refractory MM (RRMM) approved by the Food and Drug Administration (FDA) are elotuzumab and daratumumab. In this article, we will discuss daratumumab with different combination therapies. The literature exploration was done using PubMed, Medline, PubMed Central, and Research Gate. Keywords used to search are monoclonal antibodies, daratumumab, RRMM, and novel agents. Our review article, which includes 21 relevant articles, demonstrated that daratumumab in different combinations showed significant progression-free survival (PFS) without severe safety concerns. However, while observing all the studies, neither of them studied the combination therapies of daratumumab in end-stage renal disease (ESRD) patients. Hence, more randomized controlled clinical trials should be done to understand and compare the effect of the combination of daratumumab with the standard of care therapies in ESRD patients.

Efficacy of Daratumumab-Based Regimens Compared to Standard of Care in Transplant-Eligible Multiple Myeloma: A Meta-Analysis

Daratumumab (dara) belongs to a class of monoclonal antibodies that target CD38 receptors expressed on multiple myeloma (MM) cells. It was first approved for MM treatment in 2015. The efficacy and safety of dara have been reported in many studies. In this analysis, we assessed the outcome of dara addition to standard of care for transplant-eligible newly diagnosed (ND) MM. We conducted a comprehensive search using PubMed, ClinicalTrial.gov, and Embase. Out of 435 articles, we included two randomized clinical trials. We computed the odds ratio (OR) of response rates and risk ratio (RR) of adverse effects using Cochrane RevMan version 5.4. A total of 1,292 patients were enrolled in both trials. The patients were randomized into the control group and the dara group. The dara group included 647 patients and the control group included 645 patients. The CASSIOPEIA trial reported the outcomes using dara, bortezomib (V), thalidomide (T), and dexamethasone (d) versus VTd. The GRIFFIN trial underlined the efficacy of dara, lenalidomide (R), and Vd in the dara group versus RVd in the control group. A pooled analysis of included studies showed an increased overall response rate (OR: 1.60; 95% CI: 1.06-2.41; p = 0.02; I ² = 65%), stringent complete response (OR: 1.59; 95% CI: 1.24-2.05; p = 0.03; I ² = 0%), and negative status for minimal residual disease (OR: 2.47; 95% CI: 1.97-3.10; p < 0.01; I ² = 66%) in the dara group as compared to the control group. However, an increased risk of neutropenia (RR: 1.80; 95% CI: 1.60-2.03; p < 0.01) and decreased risk of peripheral neuropathy (RR: 0.92; 95% CI: 0.86-0.99; p = 0.02; I ² = 52%) were observed in the dara group. Dara addition to the standard of care regimen for transplant-eligible NDMM has promising outcomes with increased efficacy and safety profile and manageable toxicity.

Evaluation of Cardiac Repolarization in the Randomized Phase 2 Study of Intermediate- or High-Risk Smoldering Multiple Myeloma Patients Treated with Daratumumab Monotherapy

Introduction

Daratumumab is a CD38-targeting monoclonal antibody that has demonstrated clinical benefit for multiple myeloma. Daratumumab inhibition of CD38, which is expressed on immune cell populations and cardiomyocytes, could potentially affect cardiac function. This QTc substudy of the phase 2 CENTAURUS study investigated the potential effect of intravenous daratumumab monotherapy on QTc prolongation and other electrocardiogram (ECG) parameters, including concentration-QTc effect modeling.

Methods

Patients had intermediate- or high-risk smoldering multiple myeloma. Patients with QT interval corrected by Fridericia’s formula (QTcF) > 470 ms, QRS interval ≥ 110 ms, or PR interval ≥ 200 ms were excluded. Triplicate ECGs were collected at screening, Dose 1, and Dose 8. Analyses of on-treatment ECGs were conducted with a time-matched baseline (primary analysis). By time-point, pharmacokinetic-pharmacodynamic (PK/PD), and outlier analyses were conducted.

Results

Of 123 patients in CENTAURUS, 31 were enrolled in the QTc substudy. Daratumumab produced a small increase in heart rate (5–12 beats per minute) of unclear significance. There was a small but clinically insignificant effect on QTc, as measured by both time-matched time-point and PK/PD analyses. The primary analysis demonstrated a maximum mean increase in QTcF of 9.1 ms (90% 2-sided upper confidence interval [CI], 14.1 ms). The primary PK/PD analysis predicted a maximum QTcF increase of 8.5 ms (90% 2-sided upper CI, 13.5 ms). No patient had an abnormal U wave, a new QTcF > 500 ms, or > 60 ms change from baseline for QTcF.

Conclusion

Analysis of ECG intervals and concentration-QTc relationships showed a small but clinically insignificant effect of daratumumab.

Trial Registration

ClinicalTrials.gov Identifier: NCT02316106.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-020-01601-w.

Daratumumab monotherapy for relapsed/refractory multiple myeloma, focussed on clinical trial-unfit patients and subsequent therapy

Real-world outcomes of daratumumab monotherapy (DM) for relapsed/refractory multiple myeloma (RRMM) have remained unclear. We conducted a multicentre retrospective study of 107 patients receiving DM for RRMM. The cohort included 64 trial-unfit patients whose characteristics could not meet inclusion criteria in two previous clinical trials (GEN501 and SIRIUS). The overall response rate (ORR), and median first and second progression-free survival (PFS1 and PFS2) and overall survival were 42·1%, and 3·6, 8·1 and 11·9 months, respectively. Refractoriness to carfilzomib and/or lenalidomide, and neutropenia (<1.0 × 10⁹ /l) resulted in poorer ORRs. An Eastern Cooperative Oncology Group Performance Status of ≥3, neutropenia (<1.0 × 10⁹ /l), thrombocytopenia (<75 × 10⁹ /l), and renal failure (glomerular filtration rate of <20 ml/min/1·73 m² ) were associated with poor PFS1 and PFS2 in respective univariate analysis. The modified trial-unfit group, based on the above factors, showed significantly negative impacts on PFS1 and PFS2 (hazard ratio 2·823 and 3·677, all P < 0·001) in multivariate analysis despite having a 34% ORR. Fatal infections occurred more often in the modified trial-unfit group than in the others (16·1% vs. 4·3%; P = 0·099). Despite failure of DM, subsequent therapy with pomalidomide-based therapy or carfilzomib-dexamethasone provided a 66·6% ORR. Real-world DM showed favourable efficacies for RRMM and, potentially, additional benefits with subsequent therapies. However, characteristics corresponding with trial-unfitness might offset the efficacy of DM.

Monoclonal antibodies as an addition to current myeloma therapy strategies

INTRODUCTION

Immunotherapy has emerged as a major class in the therapeutic arsenal of multiple myeloma. Cell-based immunotherapy (CAR T-cells) and monoclonal antibody-based immunotherapy (naked monoclonal antibodies, antibody-drug conjugates, and bispecific T-cell engagers) are the two cornerstones of this novel approach for myeloma patients. Among numerous targets evaluated in the previous decade; CD38, SLAMF7, and, more recently, BCMA stand as the most promising.

AREAS COVERED

This review presents and discusses the currently available data regarding monoclonal antibodies in the treatment of multiple myeloma.

EXPERT OPINION

Anti-CD38-naked monoclonal antibodies have become a standard-of-care in multiple myeloma, greatly improving the depth and duration of response when combined with conventional therapy. Elotuzumab is approved in the relapse setting in combination with pomalidomide and maybe an interesting option in patients whose disease became refractory to anti-CD38 monoclonal antibodies. Anti-BCMA drug conjugates and bispecific T-cell engager antibodies are promising new molecules in the multiple myeloma armamentarium.

Daratumumab monotherapy for patients with intermediate-risk or high-risk smoldering multiple myeloma: a randomized, open-label, multicenter, phase 2 study (CENTAURUS)

Current guidelines for smoldering multiple myeloma (SMM) recommend active monitoring until the onset of multiple myeloma (MM) before initiating treatment or enrollment in a clinical trial. Earlier intervention may delay progression to MM. In CENTAURUS, 123 patients with intermediate-risk or high-risk SMM were randomly assigned to daratumumab 16 mg/kg intravenously on extended intense (intense), extended intermediate (intermediate), or short dosing schedules. At the prespecified primary analysis (15.8-month median follow-up), the complete response (CR) rates (co-primary endpoint) were 2.4%, 4.9%, and 0% for intense, intermediate, and short dosing, respectively; the co-primary endpoint of CR rate >15% was not met. Progressive disease (PD)/death rates (number of patients who progressed or died divided by total duration of progression-free survival [PFS] in patient-years; co-primary endpoint) for intense, intermediate, and short dosing were 0.055 (80% confidence interval [CI], 0.014-0.096), 0.102 (80% CI, 0.044-0.160), and 0.206 (80% CI, 0.118-0.295), respectively, translating to a median PFS ≥24 months in all arms (P < 0.0001, <0.0001, and =0.0213, respectively). With longer follow-up (median follow-up, 25.9 months), CR rates were 4.9%, 9.8%, and 0% for intense, intermediate, and short dosing, respectively. PD/death rates for intense, intermediate, and short dosing were 0.059 (80% CI, 0.025-0.092), 0.107 (80% CI, 0.058-0.155), and 0.150 (80% CI, 0.089-0.211), respectively, again translating to a median PFS ≥ 24 months in all arms (P < 0.0001 for all arms). Twenty-four-month PFS rates were 89.9% (90% CI, 78.5-95.4%), 82.0% (90% CI, 69.0-89.9%), and 75.3% (90% CI, 61.1-85.0%) for intense, intermediate, and short dosing, respectively. Pharmacokinetic analyses indicated that intense dosing maintained target-saturating trough concentrations in most patients throughout weekly, every-2-week, and every-4-week dosing periods. No new safety signals were observed. These data provide the basis for an ongoing phase 3 study of daratumumab in SMM.

CD38 Expression by Myeloma Cells and Its Role in the Context of Bone Marrow Microenvironment: Modulation by Therapeutic Agents

In the last decades CD38 has emerged as an attractive target for multiple myeloma (MM). CD38 is a novel multifunctional glycoprotein that acts as a receptor, adhesion molecule interacting with CD31 and as an ectoenzyme. As an ectoenzyme, CD38 functions as a metabolic sensor catalyzing the extracellular conversion of NAD+ to the immunosuppressive factor adenosine (ADO). Other ectoenzymes, CD73 and CD203a, together with CD38, are also involved in the alternative axis of extracellular production of ADO, bypassing the canonical pathway mediated by CD39. CD38 is ubiquitously expressed in the bone marrow microenvironment; however, only MM cells display a very high surface density, which lead to the development of several anti-CD38 monoclonal antibodies (mAbs). The efficacy of anti-CD38 mAbs depends from the presence of CD38 on the surface of MM and immune-microenvironment cells. Interestingly, it has been reported that several drugs like lenalidomide, panobinostat, the all-trans retinoic acid and the DNA methyltransferase inhibitors may increase the expression of CD38. Hence, the possibility to modulate CD38 by increasing its expression on MM cells is the pre-requisite to potentiate the clinical efficacy of the anti-CD38 mAbs and to design clinical trials with the combination of anti-CD38 mAbs and these drugs.

Relapsed refractory multiple myeloma: a comprehensive overview

Most patients with relapsed/refractory multiple myeloma (RRMM) have been treated with drug combinations including a proteasome inhibitor (PI) and/or an immunomodulatory drug (IMiD). The goal of therapy for such patients is therefore to achieve disease control with acceptable toxicity and patient-defined decent quality of life. Physicians face a difficult task not only deciding who to treat, but also when to treat and how to treat, utilizing knowledge of previously administered therapies, patient comorbidities, potential adverse events, and patient wishes to make such a critical decision. New drugs and combination regimens are continuously underway thus broadening the options for therapy and giving way to a more individualized approach for patients with RRMM. The integration of novel agents into the treatment paradigm has shifted the perception of multiple myeloma (MM) from an incurable, fatal disease to a manageable, chronic one. This comprehensive review addresses the results and challenges posed by many of the newer agents for the treatment of RRMM. It attempts to propose a universal strategy for optimal therapy decision-making thus answering three simple fundamental questions-when to treat, how to treat, and how long to treat for.

Disseminated Cryptococcosis in a Patient with Multiple Myeloma Treated with Daratumumab, Lenalidomide, and Dexamethasone

We report a case of disseminated cryptococcosis in a patient with multiple myeloma (MM) during treatment with daratumumab, lenalidomide, and dexamethasone (DRd). A 62-year-old woman, who was diagnosed with IgGλ type MM, was treated with three cycles of bortezomib and dexamethasone and subsequently treated with three cycles of DRd before admission. She reached a stringent complete response and presented with lethargy and seizure. Laboratory findings revealed severe CD4 lymphopenia, and Cryptococcus neoformans was detected in her cerebrospinal fluid and blood culture. The risk of developing an opportunistic infection should be considered in patients treated with daratumumab.

Poly(ADP-Ribose) Polymerases in Host-Pathogen Interactions, Inflammation, and Immunity

The literature review presented here details recent research involving members of the poly(ADP-ribose) polymerase (PARP) family of proteins. Among the 17 recognized members of the family, the human enzyme PARP1 is the most extensively studied, resulting in a number of known biological and metabolic roles. This review is focused on the roles played by PARP enzymes in host-pathogen interactions and in diseases with an associated inflammatory response. In mammalian cells, several PARPs have specific roles in the antiviral response; this is perhaps best illustrated by PARP13, also termed the zinc finger antiviral protein (ZAP). Plant stress responses and immunity are also regulated by poly(ADP-ribosyl)ation. PARPs promote inflammatory responses by stimulating proinflammatory signal transduction pathways that lead to the expression of cytokines and cell adhesion molecules. Hence, PARP inhibitors show promise in the treatment of inflammatory disorders and conditions with an inflammatory component, such as diabetes, arthritis, and stroke. These functions are correlated with the biophysical characteristics of PARP family enzymes. This work is important in providing a comprehensive understanding of the molecular basis of pathogenesis and host responses, as well as in the identification of inhibitors. This is important because the identification of inhibitors has been shown to be effective in arresting the progression of disease.

High-Parameter Mass Cytometry Evaluation of Relapsed/Refractory Multiple Myeloma Patients Treated with Daratumumab Demonstrates Immune Modulation as a Novel Mechanism of Action

Daratumumab is a CD38‐targeted human monoclonal antibody with direct anti‐myeloma cell mechanisms of action. Flow cytometry in relapsed and/or refractory multiple myeloma (RRMM) patients treated with daratumumab revealed cytotoxic T‐cell expansion and reduction of immune‐suppressive populations, suggesting immune modulation as an additional mechanism of action. Here, we performed an in‐depth analysis of the effects of daratumumab on immune‐cell subpopulations using high‐dimensional mass cytometry. Whole‐blood and bone‐marrow baseline and on‐treatment samples from RRMM patients who participated in daratumumab monotherapy studies (SIRIUS and GEN501) were evaluated with high‐throughput immunophenotyping. In daratumumab‐treated patients, the intensity of CD38 marker expression decreased on many immune cells in SIRIUS whole‐blood samples. Natural killer (NK) cells were depleted with daratumumab, with remaining NK cells showing increased CD69 and CD127, decreased CD45RA, and trends for increased CD25, CD27, and CD137 and decreased granzyme B. Immune‐suppressive population depletion paralleled previous findings, and a newly observed reduction in CD38⁺ basophils was seen in patients who received monotherapy. After 2 months of daratumumab, the T‐cell population in whole‐blood samples from responders shifted to a CD8 prevalence with higher granzyme B positivity (P = 0.017), suggesting increased killing capacity and supporting monotherapy‐induced CD8⁺ T‐cell activation. High‐throughput cytometry immune profiling confirms and builds upon previous flow cytometry data, including comparable CD38 marker intensity on plasma cells, NK cells, monocytes, and B/T cells. Interestingly, a shift toward cytolytic granzyme B⁺ T cells was also observed and supports adaptive responses in patients that may contribute to depth of response. © 2018 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.

Daratumumab for Delayed Red-Cell Engraftment after Allogeneic Transplantation

Daratumumab, a human IgG1κ monoclonal antibody targeting CD38, is used to treat multiple myeloma. We describe successful treatment with daratumumab in a case of treatment-refractory pure red-cell aplasia after ABO-mismatched allogeneic stem-cell transplantation. The patient was a 72-year-old man with the myelodysplastic syndrome who received a transplant from an HLA-matched, unrelated donor with a major ABO incompatibility (blood group A in the donor and blood group O in the recipient). The patient had persistent circulating anti-A antibodies and no red-cell recovery 200 days after transplantation. Standard treatments had no effect. Within 1 week after the initiation of treatment with daratumumab, he no longer required transfusions.

Daratumumab plus lenalidomide and dexamethasone versus lenalidomide and dexamethasone in relapsed or refractory multiple myeloma: updated analysis of POLLUX

In the POLLUX study, daratumumab plus lenalidomide/dexamethasone significantly reduced risk of progression/death versus lenalidomide/dexamethasone alone in relapsed/refractory multiple myeloma. We provide one additional year of follow up and include the effect on minimal residual disease and in clinically relevant subgroups. After 25.4 months of follow up, daratumumab plus lenalidomide/dexamethasone prolonged progression-free survival versus lenalidomide/dexamethasone alone (median not reached vs. 17.5 months; hazard ratio, 0.41; 95% confidence interval, 0.31-0.53; P<0.0001). The overall response rate was 92.9% versus 76.4%, and 51.2% versus 21.0% achieved a complete response or better, respectively (both P<0.0001). At the 10⁻⁵ sensitivity threshold, 26.2% versus 6.4% were minimal residual disease–negative, respectively (P<0.0001). Post hoc analyses of clinically relevant patient subgroups demonstrated that progression-free survival was significantly prolonged for daratumumab plus lenalidomide/dexamethasone versus lenalidomide/dexamethasone regardless of number of prior lines of therapy. Patients previously treated with lenalidomide or thalidomide and those refractory to bortezomib received similar benefits (all P<0.01). Treatment benefit with daratumumab plus lenalidomide/dexamethasone was maintained in high-risk patients (median progression-free survival 22.6 vs. 10.2 months; hazard ratio, 0.53; 95% confidence interval, 0.25-1.13; P=0.0921) and patients with treatment-free intervals of >12 and ≤12 months and >6 and ≤6 months. No new safety signals were observed. In relapsed/refractory multiple myeloma patients, daratumumab plus lenalidomide/dexamethasone continued to improve progression-free survival and deepen responses versus lenalidomide/dexamethasone. Trial Registration: clinicaltrials.gov identifier: 02076009.

The expansion of targetable biomarkers for CAR T cell therapy

Biomarkers are an integral part of cancer management due to their use in risk assessment, screening, differential diagnosis, prognosis, prediction of response to treatment, and monitoring progress of disease. Recently, with the advent of Chimeric Antigen Receptor (CAR) T cell therapy, a new category of targetable biomarkers has emerged. These biomarkers are associated with the surface of malignant cells and serve as targets for directing cytotoxic T cells. The first biomarker target used for CAR T cell therapy was CD19, a B cell marker expressed highly on malignant B cells. With the success of CD19, the last decade has shown an explosion of new targetable biomarkers on a range of human malignancies. These surface targets have made it possible to provide directed, specific therapy that reduces healthy tissue destruction and preserves the patient's immune system during treatment. As of May 2018, there are over 100 clinical trials underway that target over 25 different surface biomarkers in almost every human tissue. This expansion has led to not only promising results in terms of patient outcome, but has also led to an exponential growth in the investigation of new biomarkers that could potentially be utilized in CAR T cell therapy for treating patients. In this review, we discuss the biomarkers currently under investigation and point out several promising biomarkers in the preclinical stage of development that may be useful as targets.

Emerging small molecule approaches to enhance the antimyeloma benefit of proteasome inhibitors

Multiple myeloma (MM) is a clonal plasma cell malignancy which, despite recent treatment advances, remains incurable in the vast majority of the over 118,000 patients in the USA afflicted with this disease. Treatment of MM has dramatically improved in the past decade with the introduction of new drugs into therapeutic strategies in both the frontline and relapse settings that has led to a significant improvement in the median overall survival (OS). These drugs have been incorporated into clinical guidelines and transformed the treatment approach to MM. Numerous classes of antimyeloma agents, i.e., alkylators, steroids, proteasome inhibitors, immunomodulatory agents, deactylase inhibitors, and monoclonal antibodies, are now FDA-approved and can be combined in doublet or triplet regimens. Moreover, many patients do not respond to therapy and those that do eventually relapse. Emerging therapies that may overcome drug resistance and improve MM treatment include that inhibit regulatory and Ub-processing components of the proteasome, a specialized variant of the proteasome known as the immunoproteasome, proteolysis-targeting chimeric molecules (PROTACS and Degronomids). Emerging strategies also include accessory plasmacytoid dendritic cells (pDCs), vaccines, checkpoint inhibitors, and chimeric antigen receptor-engineered T (CAR-T) cells. Advances in understanding proteasome and plasma cell biology may allow for earlier treatment of MM patients using rationally informed combination therapies with curative potential.

Pharmacokinetics of Daratumumab Following Intravenous Infusion in Relapsed or Refractory Multiple Myeloma After Prior Proteasome Inhibitor and Immunomodulatory Drug Treatment

Daratumumab is a CD38 monoclonal antibody recently approved for the treatment of multiple myeloma (MM). We report daratumumab pharmacokinetic data from GEN501, a phase I/II dose-escalation (0.005–24 mg/kg) and dose-expansion (8 or 16 mg/kg) study, and SIRIUS, a phase II study (8 or 16 mg/kg), in relapsed or refractory MM. Noncompartmental analysis was conducted to characterize daratumumab pharmacokinetics, and, in both studies, daratumumab exhibited nonlinear pharmacokinetic characteristics. Decreasing daratumumab clearance with increasing dose suggests saturation of target-mediated clearance at higher dose levels, whereas decreasing clearance over time with repeated dosing may be due to tumor burden reductions as CD38-positive cells are eliminated. These and other pharmacokinetic data analyses support the use of the recommended dose regimen of daratumumab (16 mg/kg weekly for 8 weeks, every 2 weeks for 16 weeks, and every 4 weeks thereafter) to rapidly saturate target-mediated clearance during weekly dosing and maintain saturation when dosing every 2 or 4 weeks.

Influence of Disease and Patient Characteristics on Daratumumab Exposure and Clinical Outcomes in Relapsed or Refractory Multiple Myeloma

OBJECTIVE

The aim of this study was to understand the influence of disease and patient characteristics on exposure to daratumumab, an immunoglobulin Gκ (IgGκ) monoclonal antibody, and clinical outcomes in relapsed or refractory multiple myeloma (MM).

PATIENTS AND METHODS

Baseline myeloma type, albumin levels, renal/hepatic function, age, sex, race, weight, Eastern Cooperative Oncology Group (ECOG) status, refractory status, and number of prior therapies were evaluated using data from two clinical studies-GEN501 (N = 104) and SIRIUS (N = 124).

RESULTS

Daratumumab clearance was approximately 110% higher in IgG myeloma patients than non-IgG myeloma patients, leading to significantly lower exposure in IgG myeloma patients based on maximum trough serum concentrations (p < 0.0001). However, the overall response rate was similar for IgG and non-IgG myeloma patients (odds ratio 1.08, 95% confidence interval 0.54-2.17, p = 0.82). For a given exposure, the drug effect was significantly higher (approximately two times) in IgG versus non-IgG patients (p = 0.03). The influence of other patient and disease characteristics on daratumumab exposure was minimal and no significant effect on efficacy was observed (p ≥ 0.1). The incidences of infections and overall grade 3 or higher adverse events in subpopulations were generally consistent with that of the overall population.

CONCLUSION

Due to competition with the MM-produced IgG M-protein for neonatal Fc receptor protection from clearance, IgG-based monoclonal antibodies in general may have significantly higher clearance and lower concentrations in IgG MM patients compared with non-IgG MM patients. Careful evaluation of the impact of exposure and patient and disease characteristics on safety and efficacy is warranted for all IgG-based monoclonal antibodies used in MM.

Comparative Efficacy of Daratumumab Monotherapy and Pomalidomide Plus Low-Dose Dexamethasone in the Treatment of Multiple Myeloma: A Matching Adjusted Indirect Comparison

BACKGROUND

Daratumumab (a human CD38-directed monoclonal antibody) and pomalidomide (an immunomodulatory drug) plus dexamethasone are both relatively new treatment options for patients with heavily pretreated multiple myeloma. A matching adjusted indirect comparison (MAIC) was used to compare absolute treatment effects of daratumumab versus pomalidomide + low-dose dexamethasone (LoDex; 40 mg) on overall survival (OS), while adjusting for differences between the trial populations.

MATERIALS AND METHODS

The MAIC method reduces the risk of bias associated with naïve indirect comparisons. Data from 148 patients receiving daratumumab (16 mg/kg), pooled from the GEN501 and SIRIUS studies, were compared separately with data from patients receiving pomalidomide + LoDex in the MM-003 and STRATUS studies.

RESULTS

The MAIC-adjusted hazard ratio (HR) for OS of daratumumab versus pomalidomide + LoDex was 0.56 (95% confidence interval [CI], 0.38-0.83; p = .0041) for MM-003 and 0.51 (95% CI, 0.37-0.69; p < .0001) for STRATUS. The treatment benefit was even more pronounced when the daratumumab population was restricted to pomalidomide-naïve patients (MM-003: HR, 0.33; 95% CI, 0.17-0.66; p = .0017; STRATUS: HR, 0.41; 95% CI, 0.21-0.79; p = .0082). An additional analysis indicated a consistent trend of the OS benefit across subgroups based on M-protein level reduction (≥50%, ≥25%, and <25%).

CONCLUSION

The MAIC results suggest that daratumumab improves OS compared with pomalidomide + LoDex in patients with heavily pretreated multiple myeloma.

IMPLICATIONS FOR PRACTICE

This matching adjusted indirect comparison of clinical trial data from four studies analyzes the survival outcomes of patients with heavily pretreated, relapsed/refractory multiple myeloma who received either daratumumab monotherapy or pomalidomide plus low-dose dexamethasone. Using this method, daratumumab conferred a significant overall survival benefit compared with pomalidomide plus low-dose dexamethasone. In the absence of head-to-head trials, these indirect comparisons provide useful insights to clinicians and reimbursement authorities around the relative efficacy of treatments.

Daratumumab monotherapy compared with historical control data in heavily pretreated and highly refractory patients with multiple myeloma: An adjusted treatment comparison

Daratumumab is a human CD38-directed monoclonal antibody approved in the United States as monotherapy for patients with multiple myeloma (MM) who have received ≥3 prior lines of therapy (LOTs), including a proteasome inhibitor (PI) and an immunomodulatory agent (IMiD) or who are double refractory to a PI and an IMiD, and in combination with lenalidomide/dexamethasone or bortezomib/dexamethasone for patients with MM who have received ≥1 prior LOT. This study compared the efficacy of daratumumab monotherapy versus historical controls through adjusted treatment comparison. Patient-level data were pooled from two daratumumab monotherapy studies (16 mg/kg; GEN501 and SIRIUS) and two independent US databases (IMS LifeLink and OPTUM), which reflect treatments used in real-world patients with MM who received ≥3 prior LOTs or were double refractory to a PI and an IMiD. Using a multivariate proportional hazards regression model, the relative treatment effect of daratumumab versus historical controls was estimated, adjusting for imbalances in characteristics between cohorts. Baseline characteristics that differed between patients treated with daratumumab (N = 148) and historical control (N = 658) were prior treatment with pomalidomide (55% vs 15%) or carfilzomib (41% vs 28%) and triple/quadruple refractory status (64% vs 14%). The adjusted overall survival-hazard ratio (OS-HR) for daratumumab versus historical control was 0.33 (95% confidence interval, 0.24-0.46) compared with 0.46 (0.35-0.59) for unadjusted HR. Impact of adjustment was mainly driven by refractory status and prior pomalidomide/carfilzomib exposure. This adjusted treatment comparison suggests that daratumumab demonstrates improved OS compared with historical control data in heavily pretreated and highly refractory MM patients.

Expression of CD38 in myeloma bone niche: A rational basis for the use of anti-CD38 immunotherapy to inhibit osteoclast formation

It is known that multiple myeloma (MM) cells express CD38 and that a recently developed human anti-CD38 monoclonal antibody Daratumumab mediates myeloma killing. However, the expression of CD38 and other functionally related ectoenzymes within the MM bone niche and the potential effects of Daratumumab on bone cells are still unknown. This study firstly defines by flow cytometry and immunohistochemistry the expression of CD38 by bone marrow cells in a cohort of patients with MM and indolent monoclonal gammopathies. Results indicate that only plasma cells expressed CD38 at high level within the bone niche. In addition, the flow cytometry analysis shows that CD38 was also expressed by monocytes and early osteoclast progenitors but not by osteoblasts and mature osteoclasts. Indeed, CD38 was lost during in vitro osteoclastogenesis. Consistently, we found that Daratumumab reacted with CD38 expressed on monocytes and its binding inhibited in vitro osteoclastogenesis and bone resorption activity from bone marrow total mononuclear cells of MM patients, targeting early osteoclast progenitors. The inhibitory effect was not observed from purified CD14⁺ cells, suggesting an indirect inhibitory effect of Daratumumab. Interestingly, all-trans retinoic acid treatment increased the inhibitory effect of Daratumumab on osteoclast formation.

These observations provide a rationale for the use of an anti-CD38 antibody-based approach as treatment for multiple myeloma-induced osteoclastogenesis.

Targeting Attenuated Interferon-α to Myeloma Cells with a CD38 Antibody Induces Potent Tumor Regression with Reduced Off-Target Activity

Interferon-α (IFNα) has been prescribed to effectively treat multiple myeloma (MM) and other malignancies for decades. Its use has waned in recent years, however, due to significant toxicity and a narrow therapeutic index (TI). We sought to improve IFNα's TI by, first, attaching it to an anti-CD38 antibody, thereby directly targeting it to MM cells, and, second, by introducing an attenuating mutation into the IFNα portion of the fusion protein rendering it relatively inactive on normal, CD38 negative cells. This anti-CD38-IFNα(attenuated) immunocytokine, or CD38-Attenukine™, exhibits 10,000-fold increased specificity for CD38 positive cells in vitro compared to native IFNα and, significantly, is ~6,000-fold less toxic to normal bone marrow cells in vitro than native IFNα. Moreover, the attenuating mutation significantly decreases IFNα biomarker activity in cynomolgus macaques indicating that this approach may yield a better safety profile in humans than native IFNα or a non-attenuated IFNα immunocytokine. In human xenograft MM tumor models, anti-CD38-IFNα(attenuated) exerts potent anti-tumor activity in mice, inducing complete tumor regression in most cases. Furthermore, anti-CD38-IFNα(attenuated) is more efficacious than standard MM treatments (lenalidomide, bortezomib, dexamethasone) and exhibits strong synergy with lenalidomide and with bortezomib in xenograft models. Our findings suggest that tumor-targeted attenuated cytokines such as IFNα can promote robust tumor killing while minimizing systemic toxicity.

Daratumumab, Bortezomib, and Dexamethasone for Multiple Myeloma

BACKGROUND

Daratumumab, a human IgGκ monoclonal antibody that targets CD38, induces direct and indirect antimyeloma activity and has shown substantial efficacy as monotherapy in heavily pretreated patients with multiple myeloma, as well as in combination with bortezomib in patients with newly diagnosed multiple myeloma.

METHODS

In this phase 3 trial, we randomly assigned 498 patients with relapsed or relapsed and refractory multiple myeloma to receive bortezomib (1.3 mg per square meter of body-surface area) and dexamethasone (20 mg) alone (control group) or in combination with daratumumab (16 mg per kilogram of body weight) (daratumumab group). The primary end point was progression-free survival.

RESULTS

A prespecified interim analysis showed that the rate of progression-free survival was significantly higher in the daratumumab group than in the control group; the 12-month rate of progression-free survival was 60.7% in the daratumumab group versus 26.9% in the control group. After a median follow-up period of 7.4 months, the median progression-free survival was not reached in the daratumumab group and was 7.2 months in the control group (hazard ratio for progression or death with daratumumab vs. control, 0.39; 95% confidence interval, 0.28 to 0.53; P<0.001). The rate of overall response was higher in the daratumumab group than in the control group (82.9% vs. 63.2%, P<0.001), as were the rates of very good partial response or better (59.2% vs. 29.1%, P<0.001) and complete response or better (19.2% vs. 9.0%, P=0.001). Three of the most common grade 3 or 4 adverse events reported in the daratumumab group and the control group were thrombocytopenia (45.3% and 32.9%, respectively), anemia (14.4% and 16.0%, respectively), and neutropenia (12.8% and 4.2%, respectively). Infusion-related reactions that were associated with daratumumab treatment were reported in 45.3% of the patients in the daratumumab group; these reactions were mostly grade 1 or 2 (grade 3 in 8.6% of the patients), and in 98.2% of these patients, they occurred during the first infusion.

CONCLUSIONS

Among patients with relapsed or relapsed and refractory multiple myeloma, daratumumab in combination with bortezomib and dexamethasone resulted in significantly longer progression-free survival than bortezomib and dexamethasone alone and was associated with infusion-related reactions and higher rates of thrombocytopenia and neutropenia than bortezomib and dexamethasone alone. (Funded by Janssen Research and Development; ClinicalTrials.gov number, NCT02136134.).

Phase 1/2 study of daratumumab, lenalidomide, and dexamethasone for relapsed multiple myeloma

Daratumumab, a human CD38 immunoglobulin G1 kappa (IgG1κ) monoclonal antibody, has activity as monotherapy in multiple myeloma (MM). This phase 1/2 study investigated daratumumab plus lenalidomide/dexamethasone in refractory and relapsed/refractory MM. Part 1 (dose escalation) evaluated 4 daratumumab doses plus lenalidomide (25 mg/day orally on days 1-21 of each cycle) and dexamethasone (40 mg/week). Part 2 (dose expansion) evaluated daratumumab at the recommended phase 2 dose (RP2D) plus lenalidomide/dexamethasone. Safety, efficacy, pharmacokinetics, immunogenicity, and accelerated daratumumab infusions were studied. In part 1 (13 patients), no dose-limiting toxicities were observed, and 16 mg/kg was selected as the R2PD. In part 2 (32 patients), median time since diagnosis was 3.2 years, with a median of 2 prior therapies (range, 1-3 prior therapies), including proteasome inhibitors (91%), alkylating agents (91%), autologous stem cell transplantation (78%), thalidomide (44%), and lenalidomide (34%); 22% of patients were refractory to the last line of therapy. Grade 3 to 4 adverse events (≥5%) included neutropenia, thrombocytopenia, and anemia. In part 2, infusion-related reactions (IRRs) occurred in 18 patients (56%); most were grade ≤2 (grade 3, 6.3%). IRRs predominantly occurred during first infusions and were more common during accelerated infusions. In part 2 (median follow-up of 15.6 months), overall response rate was 81%, with 8 stringent complete responses (25%), 3 complete responses (9%), and 9 very good partial responses (28%). Eighteen-month progression-free and overall survival rates were 72% (95% confidence interval, 51.7-85.0) and 90% (95% confidence interval, 73.1-96.8), respectively. Daratumumab plus lenalidomide/dexamethasone resulted in rapid, deep, durable responses. The combination was well tolerated and consistent with the safety profiles observed with lenalidomide/dexamethasone or daratumumab monotherapy. This trial was registered at www.clinicaltrials.gov as #NCT01615029.

Analysis of Real-World Data on Overall Survival in Multiple Myeloma Patients With ≥3 Prior Lines of Therapy Including a Proteasome Inhibitor (PI) and an Immunomodulatory Drug (IMiD), or Double Refractory to a PI and an IMiD

BACKGROUND

This retrospective study evaluated the treatment patterns in and overall survival (OS) of multiple myeloma (MM) patients who were refractory to a proteasome inhibitor (PI) and an immunomodulatory drug (IMiD) or who had received three or more prior lines of therapy (LOTs) including a PI and an IMiD.

METHODS

Electronic health records in the IMS LifeLink and OPTUM databases were screened for indexing periods of 2000-2014 and 2007-2014, respectively. Patients who were refractory to both a PI and an IMiD (criterion 1) or who received three or more prior LOTs (including a PI and an IMiD) and showed disease progression within 60 days of their most recent regimen (criterion 2) comprised the eligible population. Median OS from time of last LOT was assessed for the full cohort, cohorts meeting criteria 1 and 2, and clinically important subgroups.

RESULTS

Of 3,929 and 3,837 patients with MM diagnoses evaluated in the IMS LifeLink and OPTUM databases, 500 and 162 met the eligibility criteria, respectively. Similar median OS was observed for eligible patients in the IMS LifeLink and OPTUM databases (7.9 vs. 7.9 months; p = .5358). In subgroup analyses of the IMS LifeLink data set, median OS was longer in patients <65 years of age than it was for those ≥65 years at eligibility (9.5 vs 6.7 months; p < .01) and in patients with good or unreported versus poor performance status at last claim (7.8 or 8.8 vs. 2.9 months; p < .0001).

CONCLUSION

The findings of this survival analysis suggest that outcomes for these patients remain poor despite the availability of newer agents.

IMPLICATIONS FOR PRACTICE

This real-world retrospective study of electronic health records examines the survival outcomes of patients with multiple myeloma who are heavily pretreated or highly refractory to currently approved treatments, including recently approved proteasome inhibitors and immunomodulatory drugs. This survival analysis showed that outcomes for these patients remain poor despite the availability of newer agents, with median overall survival of approximately 8 months. These findings highlight a critical need to develop novel therapies for these patients and also serve as a reference point against which emerging agents for heavily pretreated or highly refractory disease may be evaluated.

Daratumumab depletes CD38+ immune regulatory cells, promotes T-cell expansion, and skews T-cell repertoire in multiple myeloma

Daratumumab targets CD38-expressing myeloma cells through a variety of immune-mediated mechanisms (complement-dependent cytotoxicity, antibody-dependent cell-mediated cytotoxicity, and antibody-dependent cellular phagocytosis) and direct apoptosis with crosslinking. These mechanisms may also target nonplasma cells that express CD38, which prompted evaluation of daratumumab's effects on CD38-positive immune subpopulations. Peripheral blood (PB) and bone marrow (BM) from patients with relapsed/refractory myeloma from 2 daratumumab monotherapy studies were analyzed before and during therapy and at relapse. Regulatory B cells and myeloid-derived suppressor cells, previously shown to express CD38, were evaluated for immunosuppressive activity and daratumumab sensitivity in the myeloma setting. A novel subpopulation of regulatory T cells (Tregs) expressing CD38 was identified. These Tregs were more immunosuppressive in vitro than CD38-negative Tregs and were reduced in daratumumab-treated patients. In parallel, daratumumab induced robust increases in helper and cytotoxic T-cell absolute counts. In PB and BM, daratumumab induced significant increases in CD8(+):CD4(+) and CD8(+):Treg ratios, and increased memory T cells while decreasing naïve T cells. The majority of patients demonstrated these broad T-cell changes, although patients with a partial response or better showed greater maximum effector and helper T-cell increases, elevated antiviral and alloreactive functional responses, and significantly greater increases in T-cell clonality as measured by T-cell receptor (TCR) sequencing. Increased TCR clonality positively correlated with increased CD8(+) PB T-cell counts. Depletion of CD38(+) immunosuppressive cells, which is associated with an increase in T-helper cells, cytotoxic T cells, T-cell functional response, and TCR clonality, represents possible additional mechanisms of action for daratumumab and deserves further exploration.

Clinical efficacy of daratumumab monotherapy in patients with heavily pretreated relapsed or refractory multiple myeloma

The efficacy and favorable safety profile of daratumumab monotherapy in multiple myeloma (MM) was previously reported. Here, we present an updated pooled analysis of 148 patients treated with daratumumab 16 mg/kg. Data were combined from part 2 of a first-in-human phase 1/2 study of patients who relapsed after or were refractory to ≥2 prior therapies and a phase 2 study of patients previously treated with ≥3 prior lines of therapy (including a proteasome inhibitor [PI] and an immunomodulatory drug [IMiD]) or were double refractory. Among the pooled population, patients received a median of 5 prior lines of therapy (range, 2 to 14 prior lines of therapy), and 86.5% were double refractory to a PI and an IMiD. Overall response rate was 31.1%, including 13 very good partial responses, 4 complete responses, and 3 stringent complete responses. The median duration of response was 7.6 months (95% confidence interval [CI], 5.6 to not evaluable [NE]). The median progression-free survival (PFS) and overall survival (OS) were 4.0 months (95% CI, 2.8-5.6 months) and 20.1 months (95% CI, 16.6 months to NE), respectively. When stratified by responders vs stable disease/minimal response vs progressive disease/NE, median PFS was 15.0 months (95% CI, 7.4 months to NE) vs 3.0 months (95% CI, 2.8-3.7 months) vs 0.9 months (95% CI, 0.9-1.0 months), respectively, and median OS was NE (95% CI, NE to NE) vs 18.5 months (95% CI, 15.1-22.4 months) vs 3.7 months (95% CI, 1.7-7.6 months), respectively. No new safety signals were identified. In this pooled data set, daratumumab 16 mg/kg monotherapy demonstrated rapid, deep, and durable responses, with a clinical benefit that extended to patients with stable disease or better.

Practical Considerations for the Use of Daratumumab, a Novel CD38 Monoclonal Antibody, in Myeloma

Monoclonal antibodies (mAbs) are a recent addition to multiple myeloma (MM) therapies and a number of mAbs directed at myeloma cell surface molecules are in development. Daratumumab is a CD38 mAb that has demonstrated substantial activity and good tolerability in four phase I, phase I/II and phase II studies as monotherapy, as well as in combination with current standard treatments in MM. The positive results obtained in the relapsed/refractory setting in patients with advanced-stage disease and in a small number of patients with newly diagnosed disease provide the rationale for the investigation of the agent in a number of ongoing phase III trials. mAbs are generally better tolerated than conventional chemotherapy; however, their use requires other special considerations. Such factors include those common to all mAbs, namely infusion-related reactions, but also factors that are observed with mAbs used in myeloma, such as interference with response assessment, or factors that are related to CD38 mAbs such as daratumumab, for instance blood typing interference. Our review provides an overview of the results from the daratumumab clinical trials conducted to date, as well as practical management considerations for the use of daratumumab based on our experience with the agent.

Multiple myeloma in the marrow: pathogenesis and treatments

Multiple myeloma (MM) is a B cell malignancy resulting in osteolytic lesions and fractures. In the disease state, bone healing is limited owing to increased osteoclastic and decreased osteoblastic activity, as well as an MM-induced forward-feedback cycle where bone-embedded growth factors further enhance tumor progression as bone is resorbed. Recent work on somatic mutation in MM tumors has provided insight into cytogenetic changes associated with this disease; the initiating driver mutations causing MM are diverse because of the complexity and multitude of mutations inherent in MM tumor cells. This manuscript provides an overview of MM pathogenesis by summarizing cytogenic changes related to oncogenes and tumor suppressors associated with MM, reviewing risk factors, and describing the disease progression from monoclonal gammopathy of undetermined significance to overt MM. It also highlights the importance of the bone marrow microenvironment (BMM) in the establishment and progression of MM, as well as associated MM-induced bone disease, and the relationship of the bone marrow to current and future therapeutics. This review highlights why understanding the basic biology of the healthy and diseased BMM is crucial in the quest for better treatments and work toward a cure for genetically diverse diseases such as MM.

Targeting CD38 with Daratumumab Monotherapy in Multiple Myeloma

BACKGROUND

Multiple myeloma cells uniformly overexpress CD38. We studied daratumumab, a CD38-targeting, human IgG1κ monoclonal antibody, in a phase 1-2 trial involving patients with relapsed myeloma or relapsed myeloma that was refractory to two or more prior lines of therapy.

METHODS

In part 1, the dose-escalation phase, we administered daratumumab at doses of 0.005 to 24 mg per kilogram of body weight. In part 2, the dose-expansion phase, 30 patients received 8 mg per kilogram of daratumumab and 42 received 16 mg per kilogram, administered once weekly (8 doses), twice monthly (8 doses), and monthly for up to 24 months. End points included safety, efficacy, and pharmacokinetics.

RESULTS

No maximum tolerated dose was identified in part 1. In part 2, the median time since diagnosis was 5.7 years. Patients had received a median of four prior treatments; 79% of the patients had disease that was refractory to the last therapy received (64% had disease refractory to proteasome inhibitors and immunomodulatory drugs and 64% had disease refractory to bortezomib and lenalidomide), and 76% had received autologous stem-cell transplants. Infusion-related reactions in part 2 were mild (71% of patients had an event of any grade, and 1% had an event of grade 3), with no dose-dependent adverse events. The most common adverse events of grade 3 or 4 (in ≥ 5% of patients) were pneumonia and thrombocytopenia. The overall response rate was 36% in the cohort that received 16 mg per kilogram (15 patients had a partial response or better, including 2 with a complete response and 2 with a very good partial response) and 10% in the cohort that received 8 mg per kilogram (3 had a partial response). In the cohort that received 16 mg per kilogram, the median progression-free survival was 5.6 months (95% confidence interval [CI], 4.2 to 8.1), and 65% (95% CI, 28 to 86) of the patients who had a response did not have progression at 12 months.

CONCLUSIONS

Daratumumab monotherapy had a favorable safety profile and encouraging efficacy in patients with heavily pretreated and refractory myeloma. (Funded by Janssen Research and Development and Genmab; ClinicalTrials.gov number, NCT00574288.).

α-Radioimmunotherapy with ²¹³Bi-anti-CD38 immunoconjugates is effective in a mouse model of human multiple myeloma

In spite of development of molecular therapeutics, multiple myeloma (MM) is fatal in most cases. CD38 is a promising target for selective treatment of MM. We tested radioimmunoconjugates consisting of the α-emitter ²¹³Bi coupled to an anti-CD38 MAb in preclinical treatment of MM. Efficacy of ²¹³Bi-anti-CD38-MAb was assayed towards different MM cell lines with regard to induction of DNA double-strand breaks, induction of apoptosis and initiation of cell cycle arrest. Moreover, mice bearing luciferase-expressing MM xenografts were treated with ²¹³Bi-anti-CD38-MAb. Therapeutic efficacy was monitored by bioluminescence imaging, overall survival and histology. ²¹³Bi-anti-CD38-MAb treatment induced DNA damage which did not result in activation of the G2 DNA-damage-response checkpoint, but instead in mitotic arrest and subsequent mitotic catastrophe. The anti-tumor effect of ²¹³Bi-anti-CD38-MAb correlated with the expression level of CD38 in each MM cell line. In myeloma xenografts, treatment with ²¹³Bi-anti-CD38-MAb suppressed tumor growth via induction of apoptosis in tumor tissue and significantly prolonged survival compared to controls. The major organ systems did not show any signs of ²¹³Bi-induced toxicity. Preclinical treatment of MM with ²¹³Bi-anti-CD38-MAb turned out as an effective therapeutic option.

Next-generation sequencing of peripheral B-lineage cells pinpoints the circulating clonotypic cell pool in multiple myeloma

The identity of the proliferative compartment of myeloma progenitor cells remains a matter of debate. Polymerase chain reaction-based studies suggested pre-switch "clonotypic" B cells sharing the immunoglobulin (Ig) rearrangement of the malignant plasma cell (M-PC), to circulate in the blood and possess stem cell-like properties. Here, we disprove this hypothesis. We screened peripheral blood IgM, IgG, and IgA repertoires of myeloma patients for the clonotypic rearrangement by next-generation sequencing. None of 12 cases showed pre-switch clonotypic transcripts. In the post-switch IgG/IgA repertoires, however, the clonotypic rearrangement was detected at high frequency in 6 of 8 patients with active disease, whereas it was undetectable after treatment, correlating with flow cytometric presence or absence of circulating M-PCs. Minor subclones with alternative post-switch isotypes suggested ongoing switch events and clonal evolution at the M-PC level. Our findings consistently show an absence of pre-switch clonotypic B cells, while M-PCs circulate in the peripheral blood and may contribute to spreading of the disease.

Elotuzumab and daratumumab: emerging new monoclonal antibodies for multiple myeloma

Multiple myeloma (MM) has been mostly incurable due to its highly complex and heterogeneous molecular abnormalities and the support from myeloma microenvironment factors. A therapeutic strategy which effectively targets relevant and specific molecule to myeloma cells, and which is potent in overcoming tumor microenvironment-mediated drug resistance needs to be developed. One of the promising fields is the development of immunotherapy using monoclonal antibodies (MoAbs) against myeloma-specific antigens. This review focuses on the basic and clinical aspects of two emerging and promising novel MoAbs for MM, elotuzumab which targets CS1 and daratumumab which targets CD38. Both antigens are relatively specific to myeloma cells and expressed in more than 90% of MM patients, and mediate adhesion of myeloma cells to bone marrow stromal cells. We also discuss the unique characteristics of the two MoAbs by comparing with other MoAbs being developed for MM.

Phenotypic detection of clonotypic B cells in multiple myeloma by specific immunoglobulin ligands reveals their rarity in multiple myeloma

In multiple myeloma, circulating “clonotypic” B cells, that express the immunoglobulin rearrangement of the malignant plasma cell clone, can be indirectly detected by PCR. Their role as potential “feeder” cells for the malignant plasma cell pool remains controversial. Here we established for the first time an approach that allows direct tracking of such clonotypic cells by labeling with patient-specific immunoglobulin ligands in 15 patients with myeloma. Fifty percent of patients showed evidence of clonotypic B cells in blood or bone marrow by PCR. Epitope-mimicking peptides from random libraries were selected on each patient's individual immunoglobulin and used as ligands to trace cells expressing the idiotypic immunoglobulin on their surface. We established a flow cytometry and immunofluorescence protocol to track clonotypic B cells and validated it in two independent monoclonal B cell systems. Using this method, we found clonotypic B cells in only one out of 15 myeloma patients. In view of the assay's validated sensitivity level of 10⁻³, this surprising data suggests that the abundance of such cells has been vastly overestimated in the past and that they apparently represent a very rare population in myeloma. Our novel tracing approach may open perspectives to isolate and analyze clonotypic B cells and determine their role in myeloma pathobiology.

Tracking human multiple myeloma xenografts in NOD-Rag-1/IL-2 receptor gamma chain-null mice with the novel biomarker AKAP-4

BACKGROUND

Multiple myeloma (MM) is a fatal malignancy ranking second in prevalence among hematological tumors. Continuous efforts are being made to develop innovative and more effective treatments. The preclinical evaluation of new therapies relies on the use of murine models of the disease.

METHODS

Here we describe a new MM animal model in NOD-Rag1null IL2rgnull (NRG) mice that supports the engraftment of cell lines and primary MM cells that can be tracked with the tumor antigen, AKAP-4.

RESULTS

Human MM cell lines, U266 and H929, and primary MM cells were successfully engrafted in NRG mice after intravenous administration, and were found in the bone marrow, blood and spleen of tumor-challenged animals. The AKAP-4 expression pattern was similar to that of known MM markers, such as paraproteins, CD38 and CD45.

CONCLUSIONS

We developed for the first time a murine model allowing for the growth of both MM cell lines and primary cells in multifocal sites, thus mimicking the disease seen in patients. Additionally, we validated the use of AKAP-4 antigen to track tumor growth in vivo and to specifically identify MM cells in mouse tissues. We expect that our model will significantly improve the pre-clinical evaluation of new anti-myeloma therapies.