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

Advances in engineered nanosystems: immunomodulatory interactions for therapeutic applications

Advances in nanotechnology have led to significant progress in the design and fabrication of nanoparticles (NPs) with improved therapeutic properties. NPs have been explored for modulating the immune system, serving as carriers for drug delivery or vaccine adjuvants, or acting as therapeutics themselves against a wide range of deadly diseases. The combination of NPs with immune system-targeting moieties has facilitated the development of improved targeted immune therapies. Targeted delivery of therapeutic agents using NPs specifically to the disease-affected cells, distinguishing them from other host cells, offers the major advantage of concentrating the therapeutic effect and reducing systemic side effects. Furthermore, the properties of NPs, including size, shape, surface charge, and surface modifications, influence their interactions with the targeted biological components. This review aims to provide insights into these diverse emerging and innovative approaches that are being developed and utilized for modulating the immune system using NPs. We reviewed various types of NPs composed of different materials and their specific application for modulating the immune system. Furthermore, we focused on the mechanistic effects of these therapeutic NPs on primary immune components, including T cells, B cells, macrophages, dendritic cells, and complement systems. Additionally, a recent overview of clinically approved immunomodulatory nanomedicines and potential future perspectives, offering new paradigms of this field, is also highlighted.

Mathematical Modeling Unveils Optimization Strategies for Targeted Radionuclide Therapy of Blood Cancers

Targeted radionuclide therapy is based on injections of cancer-specific molecules conjugated with radioactive nuclides. Despite the specificity of this treatment, it is not devoid of side-effects limiting its use and is especially harmful for rapidly proliferating organs well perfused by blood, like bone marrow. Optimization of radioconjugates administration accounting for toxicity constraints can increase treatment efficacy. Based on our experiments on disseminated multiple myeloma mouse model treated by 225Ac-DOTA-daratumumab, we developed a mathematical model which investigation highlighted the following principles for optimization of targeted radionuclide therapy. 1) Nuclide to antibody ratio importance. The density of radioconjugates on cancer cells determines the density of radiation energy deposited in them. Low labeling ratio as well as accumulation of unlabeled antibodies and antibodies attached to decay products in the bloodstream can mitigate cancer radiation damage due to excessive occupation of specific receptors by antibodies devoid of radioactive nuclides. 2) Cancer binding capacity-based dosing. The rate of binding of drug to cancer cells depends on the total number of their specific receptors, which therefore can be estimated from the pharmacokinetic curve of diagnostic radioconjugates. Injection of doses significantly exceeding cancer binding capacity should be avoided since radioconjugates remaining in the bloodstream have negligible efficacy to toxicity ratio. 3) Particle range-guided multi-dosing. The use of short-range particle emitters and high-affinity antibodies allows for robust treatment optimization via initial saturation of cancer binding capacity, enabling redistribution of further injected radioconjugates and deposited dose towards still viable cells that continue expressing specific receptors.

Role of Immune Cells and Immunotherapy in Multiple Myeloma

The clinical signs of multiple myeloma, a plasma cell (PC) dyscrasia, include bone loss, renal damage, and paraproteinemia. It can be defined as the uncontrolled growth of malignant PCs within the bone marrow. The distinctive bone marrow milieu that regulates the progression of myeloma disease involves interactions between plasma and stromal cells, and myeloid and lymphoid cells. These cells affect the immune system independently or because of a complicated web of interconnections, which promotes disease development and immune evasion. Due to the importance of these factors in the onset of disease, various therapeutic strategies have been created that either target or improve the immunological processes that influence disease progression. The immune system has a role in the mechanism of action of multiple myeloma treatments. The main contributions of immune cells to the bone marrow microenvironment, as well as how they interact and how immune regulation might lead to therapeutic effects, are covered in this study.

Daratumumab in Indian patients with relapsed and refractory multiple myeloma: a prospective, multicenter, phase IV study

Aim: To assess the safety and effectiveness of daratumumab monotherapy in Indian patients with relapsed/refractory multiple myeloma. Methods: In this prospective, multicenter, phase IV study, patients (aged ≥18 years) received intravenous daratumumab (16 mg/kg) in six cycles. Safety was the primary end point. Results: Of the 139 patients included, 121 (87.1%) experienced ≥1 treatment-emergent adverse events (TEAEs; 53 [38.1%] drug-related), 32 (23%) had ≥1 serious TEAEs (five [3.6%] drug-related) and 16 (11.5%) deaths were reported (one death [0.7%] was drug-related). Overall response rate was 26.3%; 62.7% of patients had stable disease. Median time to first response and median progression-free survival were 5.2 and 5.9 months, respectively. Functional status and well-being were improved. Conclusion: Daratumumab showed an acceptable and expected safety profile with consistent efficacy, providing a novel therapeutic option for relapsed/refractory multiple myeloma management in India.

Role of daratumumab in the frontline management of multiple myeloma: a narrative review

INTRODUCTION

The prevalence of multiple myeloma (MM) has gradually increased over the last few decades in India due to growing population, better disease awareness, and improved diagnostic procedures. Despite such advances, MM remains an incurable and relapsing disease due to its heterogeneity and genomic instability. With the inclusion of monoclonal antibodies, especially daratumumab in the frontline regimen, the management landscape of MM has improved significantly resulting in better disease control and patient outcomes.

AREAS COVERED

This review aims to provide an in-depth summary of efficacy and safety of frontline daratumumab therapy in treatment of MM including patients with high-risk cytogenetic profile.

EXPERT OPINION

Based on the review of literature, daratumumab in frontline therapy has demonstrated improved efficacy in terms of reduction in disease progression or death, and superior minimal residual disease (MRD)-negativity rates with an acceptable safety profile in patients with newly diagnosed MM (NDMM) including patients with high-risk cytogenetic profile. Daratumumab alone or in combination with other drugs has shown similar clinical outcomes in patients with relapsed/refractory MM. Hence, daratumumab can be used upfront in patients with MM.

IBI379, a novel B cell maturation antigen/CD3 bispecific T-cell engager, displays high antitumor efficacy in preclinical models of multiple myeloma

Multiple myeloma (MM) is a hematological malignancy that results from the malignant proliferation of plasma cells in the bone marrow. B cell maturation antigen (BCMA) is highly selectively expressed in malignant plasma cells and is a novel therapeutic target for MM. Here, we developed a bispecific T cell engager, IBI379, that targets BCMA and CD3, and investigated its antitumor efficacy against MM. IBI379 showed strong binding affinity with both BCMA and CD3, which triggered T cell activation, proliferation, and cytokine release. An in vitro study demonstrated that IBI379 induced the lysis of MM cells expressing differing levels of BCMA on the cell surface. Administration of IBI379 in H929 or Daudi-BCMA cell xenograft mouse models significantly inhibited tumor growth without inducing body weight loss. The mechanism of action study revealed the accumulation of CD4⁺CD8⁺ T cells and granzyme B-positive T cells in tumors that were treated with IBI379. Moreover, administration of low dose of IBI379 in cynomolgus monkeys was well-tolerated and induced the depletion of BCMA⁺ B cells and a mild transient increase of cytokines. Collectively, these results demonstrate that IBI379 is a highly potent therapeutic strategy for depleting BCMA-positive B cells and is a promising approach for the treatment of MM.

The CD38 glycohydrolase and the NAD sink: implications for pathological conditions

Nicotinamide adenine dinucleotide (NAD) acts as a cofactor in several oxidation-reduction (redox) reactions and is a substrate for a number of nonredox enzymes. NAD is fundamental to a variety of cellular processes including energy metabolism, cell signaling, and epigenetics. NAD homeostasis appears to be of paramount importance to health span and longevity, and its dysregulation is associated with multiple diseases. NAD metabolism is dynamic and maintained by synthesis and degradation. The enzyme CD38, one of the main NAD-consuming enzymes, is a key component of NAD homeostasis. The majority of CD38 is localized in the plasma membrane with its catalytic domain facing the extracellular environment, likely for the purpose of controlling systemic levels of NAD. Several cell types express CD38, but its expression predominates on endothelial cells and immune cells capable of infiltrating organs and tissues. Here we review potential roles of CD38 in health and disease and postulate ways in which CD38 dysregulation causes changes in NAD homeostasis and contributes to the pathophysiology of multiple conditions. Indeed, in animal models the development of infectious diseases, autoimmune disorders, fibrosis, metabolic diseases, and age-associated diseases including cancer, heart disease, and neurodegeneration are associated with altered CD38 enzymatic activity. Many of these conditions are modified in CD38-deficient mice or by blocking CD38 NADase activity. In diseases in which CD38 appears to play a role, CD38-dependent NAD decline is often a common denominator of pathophysiology. Thus, understanding dysregulation of NAD homeostasis by CD38 may open new avenues for the treatment of human diseases.

Practical Considerations for the Daratumumab Management in Portuguese Routine Clinical Practice: Recommendations From an Expert Panel of Hematologists

The recent therapeutic progress in multiple myeloma (MM) has led to the introduction of novel and highly potent drug classes. Daratumumab was the first CD38-targeting antibody showing to be effective and safe in MM patients as monotherapy and in combination regimens, which led to its rapid implementation in clinical practice. Considering that treatment discontinuation for drug-related adverse events can impact patients’ quality of life and outcomes, the treatment decision should consider different factors and be weighted for each patient individually. Here, we aimed to guide clinicians using daratumumab treatment for MM by addressing practical real-world considerations based on an expert panel of Portuguese hematologists. Carefully following the recommendations mentioned in daratumumab’s SmPC, and of those from other drugs used in combination regimens, along with ensuring a good communication with all healthcare professionals involved, is critical to prevent any complications arising from treatment. The risk of infection should be assessed for all patients under treatment with daratumumab and patients should be educated on the potential adverse events. Recommendations on prophylaxis and vaccination should be considered to avoid infections, and delays in the planned therapeutic schedule may be required to prevent adverse consequences of hematological toxicity. Daratumumab treatment is effective and feasible in patients with renal impairment, although careful patient monitoring and a frequent communication with the Nephrology department are of the utmost importance. Sharing clinical practice plays an important role in medical education by allowing to maximize treatment efficacy and minimize its safety risks.

Mouse CD38-Specific Heavy Chain Antibodies Inhibit CD38 GDPR-Cyclase Activity and Mediate Cytotoxicity Against Tumor Cells

CD38 is the major NAD⁺-hydrolyzing ecto-enzyme in most mammals. As a type II transmembrane protein, CD38 is also a promising target for the immunotherapy of multiple myeloma (MM). Nanobodies are single immunoglobulin variable domains from heavy chain antibodies that naturally occur in camelids. Using phage display technology, we isolated 13 mouse CD38-specific nanobodies from immunized llamas and produced these as recombinant chimeric mouse IgG2a heavy chain antibodies (hcAbs). Sequence analysis assigned these hcAbs to five distinct families that bind to three non-overlapping epitopes of CD38. Members of families 4 and 5 inhibit the GDPR-cyclase activity of CD38. Members of families 2, 4 and 5 effectively induce complement-dependent cytotoxicity against CD38-expressing tumor cell lines, while all families effectively induce antibody dependent cellular cytotoxicity. Our hcAbs present unique tools to assess cytotoxicity mechanisms of CD38-specific hcAbs in vivo against tumor cells and potential off-target effects on normal cells expressing CD38 in syngeneic mouse tumor models, i.e. in a fully immunocompetent background.

Comparison of CD38-Targeted α- Versus β-Radionuclide Therapy of Disseminated Multiple Myeloma in an Animal Model

Targeted therapies for multiple myeloma (MM) include the anti-CD38 antibody daratumumab, which, in addition to its inherent cytotoxicity, can be radiolabeled with tracers for imaging and with β- and α-emitter radionuclides for radioimmunotherapy. Methods: We have compared the potential therapeutic efficacy of β- versus α-emitter radioimmunotherapy using radiolabeled DOTA-daratumumab in a preclinical model of disseminated multiple myeloma. Multiple dose levels were investigated to find the dose with the highest efficacy and lowest toxicity. Results: In a dose–response study with the β-emitter 177Lu-DOTA-daratumumab, the lowest tested dose, 1.85 MBq, extended survival from 37 to 47 d but did not delay tumor growth. Doses of 3.7 and 7.4 MBq extended survival to 55 and 58 d, respectively, causing a small equivalent delay in tumor growth, followed by regrowth. The higher dose, 11.1 MBq, eradicated the tumor but had no effect on survival compared with untreated controls, because of whole-body toxicity. In contrast, the α-emitter 225Ac-DOTA-daratumumab had a dose-dependent effect, in which 0.925, 1.85, and 3.7 kBq increased survival, compared with untreated controls (35 d), to 47, 52, and 73 d, respectively, with a significant delay in tumor growth for all 3 doses. Higher doses of 11.1 and 22.2 kBq resulted in equivalent survival to 82 d but with significant whole-body toxicity. Parallel studies with untargeted 225Ac-DOTA-trastuzumab conferred no improvement over untreated controls and resulted in whole-body toxicity. Conclusion: We conclude, and mathematic modeling confirms, that maximal biologic doses were achieved by targeted α-therapy and demonstrated 225Ac to be superior to 177Lu in delaying tumor growth and decreasing whole-body toxicity.

Daratumumab induces mechanisms of immune activation through CD38+ NK cell targeting

Daratumumab (Dara), a multiple myeloma (MM) therapy, is an antibody against the surface receptor CD38, which is expressed not only on plasma cells but also on NK cells and monocytes. Correlative data have highlighted the immune-modulatory role of Dara, despite the paradoxical observation that Dara regimens decrease the frequency of total NK cells. Here we show that, despite this reduction, NK cells play a pivotal role in Dara anti-MM activity. CD38 on NK cells is essential for Dara-induced immune modulation, and its expression is restricted to NK cells with effector function. We also show that Dara induces rapid CD38 protein degradation associated with NK cell activation, leaving an activated CD38-negative NK cell population. CD38+ NK cell targeting by Dara also promotes monocyte activation, inducing an increase in T cell costimulatory molecules (CD86/80) and enhancing anti-MM phagocytosis activity ex-vivo and in vivo. In support of Dara’s immunomodulating role, we show that MM patients that discontinued Dara therapy because of progression maintain targetable unmutated surface CD38 expression on their MM cells, but retain effector cells with impaired cellular immune function. In summary, we report that CD38+ NK cells may be an unexplored therapeutic target for priming the immune system of MM patients.

Daratumumab

Multiple myeloma is a proliferative disorder of plasma cells in the bone marrow with excessive monoclonal protein production. Despite the evolution of multiple drugs and management strategies including maintenance and autologous stem cell transplantation, the long-term results still remain undesirable. Those patients with double refractoriness to immunomodulatory drugs and proteosome inhibitors have dismal prognosis and rarely get back into durable remission. The identification of CD38 as a therapeutic target for multiple myeloma resulted in the clinical development of anti-CD38 antibodies. Daratumumab is an IgG1 human monoclonal antibody that binds to the CD38 protein. The implementation of daratumumab in clinical practice is widely considered as a significant milestone in the management of multiple myeloma. The salient pharmacological aspects and clinical evolution of the drug are briefly discussed in this review.

Anti-GPRC5D/CD3 Bispecific T-Cell-Redirecting Antibody for the Treatment of Multiple Myeloma

Although treatment advances over recent decades have significantly improved survival of patients with multiple myeloma, there is still an unmet medical need for more effective treatments. In this study, we identified G-protein-coupled receptor family C group 5 member D (GPRC5D) expression on the surface of malignant cells involved in multiple myeloma, but except for plasma cells and B cells, not at appreciable levels on normal hematopoietic cells and bone marrow progenitors, including hematopoietic stem cells. In addition, we constructed IgG-based anti-GPRC5D/CD3 bispecific T-cell-redirecting antibodies (GPRC5D TRAB), which suppressed the tumor growth of GPRC5D-positive myeloma cells through the activation of T cells in vitro and in vivo in xenograft models. Collectively, these findings suggest that GPRC5D is an antigen specific to multiple myeloma and a potential target of TRAB therapy.

Daratumumab and dexamethasone is safe and effective for triple refractory myeloma patients: final results of the IFM 2014-04 (Etoile du Nord) trial

Single agent daratumumab has shown clinical activity in relapsed, refractory multiple myeloma (RRMM). The Intergroupe Francophone du Myélome 2014-04 trial was designed to further investigate daratumumab in combination with dexamethasone in triple RRMM patients. Patients received daratumumab infusions in combination with weekly dexamethasone until disease progression or unacceptable toxicity. Fifty-seven patients were included in the trial and evaluable for response. The overall response rate and the clinical benefit rate were 33% (n = 19) and 48% (n = 27), respectively. Five (8·8%) patients achieved a very good partial response or better. The median time to response was 4 weeks. For responding patients, the median progression-free survival was 6·6 months, compared to 3·7 months (3·0-5·5) for those with a minimal or stable disease. The median overall survival (OS) for all patients was 16·7 months (11·2-24·0). For responding patients, the median OS was 23·23 months, whereas that of patients with progressive disease was 2·97 months. The incidence of infusion-related reactions was 37%; all cases were manageable and did not lead to dose reduction or permanent treatment discontinuation. These data demonstrate that treatment with daratumumab and dexamethasone results in a meaningful long-term benefit with an acceptable safety profile for patients with triple RRMM.

Expression analysis of two SLAM family receptors, SLAMF2 and SLAMF7, in patients with multiple myeloma

Monoclonal antibodies against surface antigens on MM cells, such as anti-SLAMF7 and anti-CD38 antibodies, represent an attractive therapeutic modality for the eradication of multiple myeloma (MM) cells. However, further exploration of target molecules is urgently needed for the development of more effective therapies. In the present study, we studied the expression of CD48 in a total of 74 primary MM samples derived from patients to evaluate SLAMF2 (CD48) as a candidate in mAb therapy for MM. Of 74 samples, 39 were subjected to SLAMF7 analysis. Most of the MM cells, defined as CD38 and CD138 double-positive cells, showed strong expression of CD48 or SLAMF7 independent of disease stage or treatment history. In these 39 samples, most MM cells showed expression of both SLAMF7 and CD48; however, several samples showed expression of either only CD48 or only SLAMF7, including seven cases that were only highly positive for SLAMF7, and five that were only highly positive for CD48. Our study demonstrates that the immune receptor CD48 is overexpressed on MM cells together with SLAMF7, and that CD48 may be considered as an alternative target for treatment of MM in cases showing weak expression of SLAMF7.

Nasal plasmacytoma: a rare cause of persistent epistaxis

Extramedullary plasmacytoma (EP) is a rare neoplasm characterized by monoclonal proliferation of plasma cells without features of multiple myeloma. EP constitutes 3% of all plasma cell tumors. Most of the cases of EP occur in the head and neck regions, especially in the aerodigestive tract. We present a case of recurrent epistaxis for 6 months and extensive workup revealed EP of the right nasal cavity. Primary care physicians and otolaryngologists should be aware of this very rare but a plausible cause of epistaxis and keep EP in the differential diagnosis of recurrent epistaxis.

Daratumumab induces CD38 internalization and impairs myeloma cell adhesion

Daratumumab (Dara), a human immunoglobulin G1 kappa (IgG1κ) monoclonal anti-CD38 antibody, has been approved by the U.S. Food and Drug Administration for the treatment of relapsed multiple myeloma (MM) as a single agent as well as in combination with immunomodulatory drugs (IMiDs) and proteasome inhibitors (PI). Although the scientific rationale behind the use of Dara in combination with IMiDs has been extensively explored, the molecular mechanisms underlying Dara-PI regimens have not yet been investigated. Here, we demonstrate that CD38 on the surface of MM cells is rapidly internalized after Dara treatment; we also show that Dara treatment impairs MM cell adhesion, an effect that can be rescued by using the endocytosis inhibitor Dynasore. Finally, we show that Dara potentiates bortezomib (BTZ) killing of MM cells in vitro and in vivo, independent of its function as an immune activator. In conclusion, our data show that Dara impairs MM cell adhesion, which results in an increased sensitivity of MM to proteasome inhibition.

Fratricide of NK Cells in Daratumumab Therapy for Multiple Myeloma Overcome by Ex Vivo-Expanded Autologous NK Cells

Purpose: Daratumumab and its use in combination with other agents is becoming a new standard of care for the treatment of multiple myeloma. We mechanistically studied how daratumumab acts on natural killer (NK) cells.Experimental Design: Quantities of NK cells in peripheral blood and/or bone marrow of patients with multiple myeloma or healthy donors were examined by flow cytometry. NK-cell apoptosis and the associated mechanism were assessed by flow cytometry and immunoblotting. Patients' NK cells were expanded in vitro using feeder cells. Combination treatment of daratumumab and expanded NK cells was performed using an MM.1S xenograft animal model.Results: CD38^-/low NK cells survived, whereas CD38⁺ NK cells were almost completely eliminated, in peripheral blood and bone marrow of daratumumab-treated multiple myeloma patients. NK-cell depletion occurred due to daratumumab-induced NK-cell fratricide via antibody-dependent cellular cytotoxicity. Consequently, CD38^-/low NK cells were more effective for eradicating multiple myeloma cells than were CD38⁺ NK cells in the presence of daratumumab. Blockade of CD38 with the F(ab)₂ fragments of daratumumab inhibited the antibody-mediated NK-cell fratricide. CD38^-/low NK cells displayed a significantly better potential for expansion than CD38⁺ NK cells, and the expanded NK cells derived from the former population were more cytotoxic than those derived from the latter against multiple myeloma cells. Therefore, infusion of ex vivo-expanded autologous NK cells from daratumumab-treated patients may improve the antibody therapy.Conclusions: We unravel a fratricide mechanism for daratumumab-mediated NK-cell depletion and provide a potential therapeutic strategy to overcome this side effect in daratumumab-treated patients with multiple myeloma. Clin Cancer Res; 24(16); 4006-17. ©2018 AACR.

Daratumumab augments alloreactive natural killer cell cytotoxicity towards CD38+ multiple myeloma cell lines in a biochemical context mimicking tumour microenvironment conditions

Natural killer (NK) cell-based immunotherapy is a promising novel approach to treat cancer. However, NK cell function has been shown to be potentially diminished by factors common in the tumor microenvironment (TME). In this study, we assessed the synergistic potential of antibody-dependent cell-mediated cytotoxicity (ADCC) and killer immunoglobin-like receptor (KIR)-ligand mismatched NK cells to potentiate NK cell antitumor reactivity in multiple myeloma (MM). Hypoxia, lactate, prostaglandin E2 (PGE2) or combinations were selected to mimic the TME. To investigate this, NK cells from healthy donors were isolated and NK cell ADCC capacity in response to MM cells was assessed in flow cytometry-based cytotoxicity and degranulation (CD107a) assays in the presence of TME factors. Hypoxia, lactate and PGE2 reduced cytotoxicity of NK cells against myeloma target cells. The addition of daratumumab (anti-CD38 antibody) augmented NK-cell cytotoxicity against target cells expressing high CD38, but not against CD38 low or negative target cells also in the presence of TME. Co-staining for inhibitory KIRs and NKG2A demonstrated that daratumumab enhanced degranulation of all NK cell subsets. Nevertheless, KIR-ligand mismatched NK cells were slightly better effector cells than KIR-ligand matched NK cells. In summary, our study shows that combination therapy using strategies to maximize activating NK cell signaling by triggering ADCC in combination with an approach to minimize inhibitory signaling through a selection of KIR-ligand mismatched donors, can help to overcome the NK-suppressive TME. This can serve as a platform to improve the clinical efficacy of NK cells.

New mAb therapies in multiple myeloma: interference with blood transfusion compatibility testing

PURPOSE OF REVIEW

Immunotherapeutic strategies are emerging as novel therapeutic approaches in multiple myeloma, with several mAbs being in advanced stages of clinical development. Of these, CD38 targeting antibodies appear very promising. In trials with anti-CD38 mAb daratumumab, all patients demonstrated panreactivity in red blood cell (RBC) panel testing, complicating the selection of compatible RBCs for transfusion. This review provides an overview of the interferences and solutions to safely transfuse these patients.

RECENT FINDINGS

CD38 is weakly expressed on human erythrocytes. Since the first reports on the interference, different solutions have been reported, including the neutralization of anti-CD38 mAbs in plasma by sCD38 or antiidiotype antibodies, CD38 depletion of RBCs using dithiothreitol or cord blood test cells, and transfusion of extensively typed RBCs.

SUMMARY

All methods have (dis)advantages, and it depends on the facilities of the immunohematology laboratory what strategy to choose. As the selection of suitable RBC units can be seriously delayed, hospitals should have protocols to communicate this interference with patients, laboratories, and physicians in a timely manner. As CD38 antibodies may also have a role in the treatment of diseases beyond hematological malignancies, chances are high that health professionals will encounter this issue in the nearby future.

Preclinical Development of CD38-Targeted [89Zr]Zr-DFO-Daratumumab for Imaging Multiple Myeloma

Multiple myeloma (MM) is a plasma B-cell hematologic cancer that causes significant skeletal morbidity. Despite improvements in survival, heterogeneity in response remains a major challenge in MM. Cluster of differentiation 38 (CD38) is a type II transmembrane glycoprotein overexpressed in myeloma cells and is implicated in MM cell signaling. Daratumumab is a U.S. Food and Drug Administration-approved high-affinity monoclonal antibody targeting CD38 that is clinically benefiting refractory MM patients. Here, we evaluated [⁸⁹Zr]Zr-desferrioxamine (DFO)-daratumumab PET/CT imaging in MM tumor models. Methods: Daratumumab was conjugated to DFO-p-benzyl-isothiocyanate (DFO-Bz-NCS) for radiolabeling with ⁸⁹Zr. Chelator conjugation was confirmed by electrospray ionization-mass spectrometry, and radiolabeling was monitored by instant thin-layer chromatography. Daratumumab was conjugated to Cyanine5 (Cy5) dye for cell microscopy. In vitro and in vivo evaluation of [⁸⁹Zr]Zr-DFO-daratumumab was performed using CD38⁺ human myeloma MM1.S-luciferase (MM1.S) cells. Cellular studies determined the affinity, immunoreactivity, and specificity of [⁸⁹Zr]Zr-DFO-daratumumab. A 5TGM1-luciferase (5TGM1)/KaLwRij MM mouse model served as control for imaging background noise. [⁸⁹Zr]Zr-DFO-daratumumab PET/CT small-animal imaging was performed in severe combined immunodeficient mice bearing solid and disseminated MM tumors. Tissue biodistribution (7 d after tracer administration, 1.11 MBq/animal, n = 4-6/group) was performed in wild-type and MM1.S tumor-bearing mice. Results: A specific activity of 55.5 MBq/nmol (0.37 MBq/μg) was reproducibly obtained with [⁸⁹Zr]Zr-daratumumab-DFO. Flow cytometry confirmed CD38 expression (>99%) on the surface of MM1.S cells. Confocal microscopy with daratumumab-Cy5 demonstrated specific cell binding. Dissociation constant, 3.3 nM (±0.58), and receptor density, 10.1 fmol/mg (±0.64), was obtained with a saturation binding assay. [⁸⁹Zr]Zr-DFO-daratumumab/PET demonstrated specificity and sensitivity for detecting CD38⁺ myeloma tumors of variable sizes (8.5-128 mm³) with standardized uptake values ranging from 2.1 to 9.3. Discrete medullar lesions, confirmed by bioluminescence images, were efficiently imaged with [⁸⁹Zr]Zr-DFO-daratumumab/PET. Biodistribution at 7 d after administration of [⁸⁹Zr]Zr-DFO-daratumumab showed prominent tumor uptake (27.7 ± 7.6 percentage injected dose per gram). In vivo blocking was achieved with a 200-fold excess of unlabeled daratumumab. Conclusion: [⁸⁹Zr]Zr-DFO- and Cy5-daratumumab demonstrated superb binding to CD38⁺ human MM cells and significantly low binding to CD38^low cells. Daratumumab bioconjugates are being evaluated for image-guided delivery of therapeutic radionuclides.

Human IgG3 with extended half-life does not improve Fc-gamma receptor-mediated cancer antibody therapies in mice

Background

Current anti-cancer therapeutic antibodies that are used in the clinic are predominantly humanized or fully human immunoglobulin G1 (IgG1). These antibodies bind with high affinity to the target antigen and are efficient in activating the immune system via IgG Fc receptors and/or complement. In addition to IgG1, three more isotypes are present in humans, of which IgG3 has been found to be superior compared to human IgG1 in inducing antibody dependent cell cytotoxicity (ADCC), phagocytosis or activation of complement in some models. Nonetheless, no therapeutic human IgG3 mAbs have been developed due to the short in vivo half-life of most known IgG3 allotypes. In this manuscript, we compared the efficacy of V-gene matched IgG1 and IgG3 anti-tumour mAb (TA99) in mice, using natural variants of human IgG3 with short- or long half-life, differing only at position 435 with an arginine or histidine, respectively.

Results

In vitro human IgG1 and IgG3 did not show any differences in opsonisation ability of B16F10-gp75 mouse melanoma cells. IgG1, however, was superior in inducing phagocytosis of tumour cells by mouse macrophages. Similarly, in a mouse peritoneal metastasis model we did not detect an improved effect of IgG3 in preventing tumour outgrowth. Moreover, replacing the arginine at position 435 for a histidine in IgG3 to enhance half-life did not result in better suppression of tumour outgrowth compared to wild type IgG3 when injected prior to tumour cell injection.

Conclusion

In conclusion, human IgG3 does not have improved therapeutic efficacy compared to human IgG1 in a mouse tumour model.

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.

Investigation and management of IgM and Waldenström-associated peripheral neuropathies: recommendations from the IWWM-8 consensus panel

Paraproteinaemic neuropathies are a heterogeneous group of disorders most frequently associated with IgM monoclonal gammopathies including Waldenström macroglobulinaemia (WM). Their consequences are significant for affected patients, and their management challenging for their physicians. The variability in clinical presentation and time course hamper classification and management. The indications for invasive investigations such as cerebrospinal fluid analysis, nerve conduction tests and sensory nerve biopsies are unclear, and the optimum way to measure clinical response to treatment unknown. When to intervene and and how to treat, also present challenges to physicians. As part of its latest deliberations at the International Workshops on WM (IWWM) in London, UK (August 2014), the IWWM8 panel have proposed a consensus approach to the diagnosis and management of peripheral neuropathies associated with IgM monoclonal gammopathies, including WM. Importantly, a consensus regarding the use of clinical outcome measures and recommended models of care for this group of patients is discussed, as well as appropriate treatment interventions.

A novel BCMA/CD3 bispecific T-cell engager for the treatment of multiple myeloma induces selective lysis in vitro and in vivo

B-cell maturation antigen (BCMA) is a highly plasma cell-selective protein that is expressed on malignant plasma cells of multiple myeloma (MM) patients and therefore is an ideal target for T-cell redirecting therapies. We developed a bispecific T-cell engager (BiTE) targeting BCMA and CD3ɛ (BI 836909) and studied its therapeutic impacts on MM. BI 836909 induced selective lysis of BCMA-positive MM cells, activation of T cells, release of cytokines and T-cell proliferation; whereas BCMA-negative cells were not affected. Activity of BI 836909 was not influenced by the presence of bone marrow stromal cells, soluble BCMA or a proliferation-inducing ligand (APRIL). In ex vivo assays, BI 836909 induced potent autologous MM cell lysis in both, newly diagnosed and relapsed/refractory patient samples. In mouse xenograft studies, BI 836909 induced tumor cell depletion in a subcutaneous NCI-H929 xenograft model and prolonged survival in an orthotopic L-363 xenograft model. In a cynomolgus monkey study, administration of BI 836909 led to depletion of BCMA-positive plasma cells in the bone marrow. Taken together, these results show that BI 836909 is a highly potent and efficacious approach to selectively deplete BCMA-positive MM cells and represents a novel immunotherapeutic for the treatment of MM.

Phase 2 study of tabalumab, a human anti-B-cell activating factor antibody, with bortezomib and dexamethasone in patients with previously treated multiple myeloma

In this double-blind, Phase 2 study, 220 patients with relapsed/refractory multiple myeloma were randomly assigned 1:1:1 to receive placebo (N = 72), tabalumab 100 mg (N = 74), or tabalumab 300 mg (N = 74), each in combination with dexamethasone 20 mg and subcutaneous bortezomib 1·3 mg/m² on a 21-day cycle. No significant intergroup differences were observed among primary (median progression-free survival [mPFS]) or secondary efficacy outcomes. The mPFS was 6·6, 7·5 and 7·6 months for the tabalumab 100, 300 mg and placebo groups, respectively (tabalumab 100 mg vs. placebo Hazard ratio (HR) [95% confidence interval (CI)] = 1·13 [0·80-1·59], P = 0·480; tabalumab 300 mg vs. placebo HR [95% CI] = 1·03 [0·72-1·45], P = 0·884). The most commonly-reported treatment-emergent adverse events were thrombocytopenia (37%), fatigue (37%), diarrhoea (35%) and constipation (32%). Across treatments, patients with low baseline BAFF (also termed TNFSF13B) expression (n = 162) had significantly longer mPFS than those with high BAFF expression (n = 55), using the 75th percentile cut-off point (mPFS [95% CI] = 8·3 [7·0-9·3] months vs. 5·8 [3·7-6·6] months; HR [95% CI] = 1·59 [1·11-2·29], P = 0·015). Although generally well tolerated, PFS was not improved during treatment with tabalumab compared to placebo. A higher dose of 300 mg tabalumab did not improve efficacy compared to the 100 mg dose. Nonetheless, BAFF appears to have some prognostic value in patients with multiple myeloma.

Hematological approaches to multiple myeloma: trends from a Brazilian subset of hematologists. A cross-sectional study

CONTEXT AND OBJECTIVE

For the last nine years, hematologists and oncologists have gathered annually at an educational symposium organized by a Brazilian and an American hospital. During the 2015 Board Review, a survey among the attendees evaluated the differences in management and treatment methods for multiple myeloma (MM).

DESIGN AND SETTING

Cross-sectional study during an educational hematology symposium in São Paulo, Brazil.

METHODS

Hematologists present at the symposium gave responses to an electronic survey by means of mobile phone.

RESULTS

Among the 350 attendees, 217 answered the questionnaire. Most of the participants believed that immunotargeting agents (iTA) might be effective for slowing MM progression in heavily pretreated patients (67%) and that continued exposure to therapy might lead to emergence of resistant clones in patients with MM (76%). Most of the physicians use maintenance therapy after hematopoietic stem cell transplantation (95%) and 45% of them would further restrict it to post-transplantation patients with underlying high-risk disease. The first-line drugs used for transplantation-ineligible patients (TI-MM) were bortezomib-thalidomide-dexamethasone (31%), bortezomib-dexamethasone (28%), lenalidomide-dexamethasone (Rd; 17%) and melphalan-based therapy (10%). Lenalidomide was the drug of choice for post-transplantation maintenance for half of the participants. No significant differences were observed regarding age or length of experience.

CONCLUSION

The treatment choices for TI-MM patients were highly heterogenous and the melphalan-based regimen represented only 10% of the first-line options. Use of maintenance therapy after transplantation was a common choice. Some results from the survey were divergent from the evidence in the literature.

Cytotoxic mechanisms of immunotherapy: Harnessing complement in the action of anti-tumor monoclonal antibodies

Several mAbs that have been approved for the treatment of cancer make use of complement-dependent cytotoxicity (CDC) to eliminate tumor cells. Comprehensive investigations, based on in vitro studies, mouse models and analyses of patient blood samples after mAb treatment have provided key insights into the details of individual steps in the CDC reaction. Based on the lessons learned from these studies, new and innovative approaches are now being developed to increase the clinical efficacy of next generation mAbs with respect to CDC. These improvements include engineering changes in the mAbs to enhance their ability to activate complement. In addition, mAb dosing paradigms are being developed that take into account the capacity as well as the limitations of the complement system to eliminate a substantial burden of mAb-opsonized cells. Over the next few years it is likely these approaches will lead to mAbs that are far more effective in the treatment of cancer.

Harnessing RNAi-based nanomedicines for therapeutic gene silencing in B-cell malignancies

Despite progress in systemic small interfering RNA (siRNA) delivery to the liver and to solid tumors, systemic siRNA delivery to leukocytes remains challenging. The ability to silence gene expression in leukocytes has great potential for identifying drug targets and for RNAi-based therapy for leukocyte diseases. However, both normal and malignant leukocytes are among the most difficult targets for siRNA delivery as they are resistant to conventional transfection reagents and are dispersed in the body. We used mantle cell lymphoma (MCL) as a prototypic blood cancer for validating a novel siRNA delivery strategy. MCL is an aggressive B-cell lymphoma that overexpresses cyclin D1 with relatively poor prognosis. Down-regulation of cyclin D1 using RNA interference (RNAi) is a potential therapeutic approach to this malignancy. Here, we designed lipid-based nanoparticles (LNPs) coated with anti-CD38 monoclonal antibodies that are specifically taken up by human MCL cells in the bone marrow of xenografted mice. When loaded with siRNAs against cyclin D1, CD38-targeted LNPs induced gene silencing in MCL cells and prolonged survival of tumor-bearing mice with no observed adverse effects. These results highlight the therapeutic potential of cyclin D1 therapy in MCL and present a novel RNAi delivery system that opens new therapeutic opportunities for treating MCL and other B-cell malignancies.