Monoclonal antibodies targeting CD38 in hematological malignancies and beyond

CAR-T Cell Therapy in Hematological Malignancies: Current Opportunities and Challenges

Chimeric antigen receptor T (CAR-T) cell therapy represents a major breakthrough in cancer treatment, and it has achieved unprecedented success in hematological malignancies, especially in relapsed/refractory (R/R) B cell malignancies. At present, CD19 and BCMA are the most common targets in CAR-T cell therapy, and numerous novel therapeutic targets are being explored. However, the adverse events related to CAR-T cell therapy might be serious or even life-threatening, such as cytokine release syndrome (CRS), CAR-T-cell-related encephalopathy syndrome (CRES), infections, cytopenia, and CRS-related coagulopathy. In addition, due to antigen escape, the limited CAR-T cell persistence, and immunosuppressive tumor microenvironment, a considerable proportion of patients relapse after CAR-T cell therapy. Thus, in this review, we focus on the progress and challenges of CAR-T cell therapy in hematological malignancies, such as attractive therapeutic targets, CAR-T related toxicities, and resistance to CAR-T cell therapy, and provide some practical recommendations.

Targeting metabolic reprogramming in chronic lymphocytic leukemia

Metabolic reprogramming, fundamentally pivotal in carcinogenesis and progression of cancer, is considered as a promising therapeutic target against tumors. In chronic lymphocytic leukemia (CLL) cells, metabolic abnormalities mediate alternations in proliferation and survival compared with normal B cells. However, the role of metabolic reprogramming is still under investigation in CLL. In this review, the critical metabolic processes of CLL were summarized, particularly glycolysis, lipid metabolism and oxidative phosphorylation. The effects of T cells and stromal cells in the microenvironment on metabolism of CLL were also elucidated. Besides, the metabolic alternation is regulated by some oncogenes and tumor suppressor regulators, especially TP53, MYC and ATM. Thus, the agents targeting metabolic enzymes or signal pathways may impede the progression of CLL. Both the inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) statins and the lipoprotein lipase inhibitor orlistat induce the apoptosis of CLL cells. In addition, a series of oxidative phosphorylation inhibitors play important roles in decreasing the proliferation of CLL cells. We epitomized recent advancements in metabolic reprogramming in CLL and discussed their clinical potentiality for innovative therapy options. Metabolic reprogramming plays a vital role in the initiation and progression of CLL. Therapeutic approaches targeting metabolism have their advantages in improving the survival of CLL patients. This review may shed novel light on the metabolism of CLL, leading to the development of targeted agents based on the reshaping metabolism of CLL cells.

Identification of New Antibodies Targeting Malignant Plasma Cells for Immunotherapy by Next-Generation Sequencing-Assisted Phage Display

To identify new antibodies for the treatment of plasma cell disorders including multiple myeloma (MM), a single-chain Fragment variable (scFv) antibody library was generated by immunizing mice with patient-derived malignant plasma cells. To enrich antibodies binding myeloma antigens, phage display with cellular panning was performed. After depleting the immune library with leukocytes of healthy donors, selection of antibodies was done with L-363 plasma cell line in two consecutive panning rounds. Monitoring the antibodies' enrichment throughout the panning by next-generation sequencing (NGS) identified several promising candidates. Initially, 41 unique scFv antibodies evolving from different B cell clones were selected. Nine of these antibodies strongly binding to myeloma cells and weakly binding to peripheral blood mononuclear cells (PBMC) were characterized. Using stably transfected Chinese hamster ovary cells expressing individual myeloma-associated antigens revealed that two antibodies bind CD38 and intercellular adhesion molecule-1 (ICAM-1), respectively, and 7 antibodies target yet unknown antigens. To evaluate the therapeutic potential of our new antibodies, in a first proof-of-concept study the CD38 binding scFv phage antibody was converted into a chimeric IgG1. Further analyses revealed that #5-CD38-IgG1 shared an overlapping epitope with daratumumab and isatuximab and had potent anti-myeloma activity comparable to the two clinically approved CD38 antibodies. These results indicate that by phage display and deep sequencing, new antibodies with therapeutic potential for MM immunotherapy can be identified.

Modified dendritic cell-derived exosomes activate both NK cells and T cells through the NKG2D/NKG2D-L pathway to kill CML cells with or without T315I mutation

BACKGROUND

Tyrosine kinase inhibitors have achieved quite spectacular advances in the treatment of chronic myeloid leukemia (CML), but disease progression and drug resistance that related to the T315I mutation, remain major obstacles. Dendritic cell-derived exosomes (Dex) induce NK cell immunity, but have yet to achieve satisfactory clinical efficacy. An approach to potentiate antitumor immunity by inducing both NK- and T-cell activation is urgently needed. Retinoic acid early inducible-1γ (RAE-1γ), a major ligand of natural killer group 2 member D (NKG2D), plays an important role in NK-cell and T-lymphocyte responses. We generated RAE-1γ enriched CML-specific Dex (CML-RAE-1γ-Dex) from dendritic cells (DCs) pulsed with lysates of RAE-1γ-expressing CML cells or T315I-mutant CML cells, aiming to simultaneously activate NK cells and T lymphocytes.

METHODS

We generated novel CML-RAE-1γ-Dex vaccines, which expressed RAE-1γ, and were loaded with CML tumor cell lysates. NK cells or T lymphocytes were coincubated with CML-RAE-1γ-Dex vaccines. Flow cytometry was performed to evaluate the activation and proliferation of these immune cells. Cytokine production and cytotoxicity toward CML cells with or without the T315I mutation were detected by ELISPOT, ELISA and LDH assays. CML models induced by BCR-ABL or BCR-ABL^T315I were used to determine the immunological function of Dex in vivo.

RESULTS

Herein, CML-RAE-1γ-Dex were prepared. CML-RAE-1γ-Dex effectively enhanced the proliferation and effector functions of NK cells, CD4⁺ T cells and CD8⁺ T cells, which in turn produced strong anti-CML efficacy in vitro. Moreover, CML-RAE-1γ-Dex-based immunotherapy inhibited leukemogenesis and generated durable immunological memory in CML mouse models. Similar immune responses were also observed with imatinib-resistant CML cells carrying the T315I mutation.

CONCLUSIONS

This approach based on CML-RAE-1γ-Dex vaccines may be a promising strategy for CML treatment, especially for cases with the T315I mutation.

Molecular Mechanism of Pathogenesis and Treatment Strategies for AL Amyloidosis

In amyloid light-chain (AL) amyloidosis, small B-cell clones (mostly plasma cell clones) present in the bone marrow proliferate and secrete unstable monoclonal free light chains (FLCs), which form amyloid fibrils that deposit in the interstitial tissue, resulting in organ injury and dysfunction. AL amyloidosis progresses much faster than other types of amyloidosis, with a slight delay in diagnosis leading to a marked exacerbation of cardiomyopathy. In some cases, the resulting heart failure is so severe that chemotherapy cannot be administered, and death sometimes occurs within a few months. To date, many clinical studies have focused on therapeutics, especially chemotherapy, to treat this disease. Because it is necessary to promptly lower FLC, the causative protein of amyloid, to achieve a hematological response, various anticancer agents targeting neoplastic plasma cells are used for the treatment of this disease. In addition, many basic studies using human specimens to elucidate the pathophysiology of AL have been conducted. Gene mutations associated with AL, the characteristics of amyloidogenic LC, and the structural specificity of amyloid fibrils have been clarified. Regarding the mechanism of cellular and tissue damage, the mass effect due to amyloid deposition, as well as the toxicity of pre-fibrillar LC, is gradually being elucidated. This review outlines the pathogenesis and treatment strategies for AL amyloidosis with respect to its molecular mechanisms.

Immunotherapy in AL Amyloidosis

OPINION STATEMENT

Light-chain amyloidosis is a rare disorder where a small clone of plasma cells is producing excess toxic light chains that deposit in various organs and cause dysfunction. Cardiac involvement is a major determinant of survival and rapid reduction of light chain is critical for recovery of organ function and overall survival. Immunotherapy targeting the clonal plasma cells and amyloid fibrils has emerged as a promising candidate. Daratumumab, both alone and in combinations with other anti-myeloma agents, is able to achieve deep hematologic responses and has greatly improved outcomes. Isatuximab, elotuzumab, and CAEL101 have also shown promising results and further studies are ongoing in the frontline as well as the relapsed/refractory setting. The frailty of AL patients and the relapsing/remitting nature of the disease present unique challenges, and the low toxicity of monoclonal antibodies makes them well-suited for these patients. Other immunotherapy agents including chimeric antigen receptor T cells, bispecific antibodies, and antibody-drug conjugates have altered the landscape in treatment of multiple myeloma, and are in the early phase of evaluation in patients with AL amyloidosis with results eagerly awaited.

Nanomedicine as a magic bullet for combating lymphoma

Hematological malignancy like lymphoma originates in lymph tissues and has a propensity to spread across other organs. Managing such tumors is challenging as conventional strategies like surgery and local treatment are not plausible options and there are high chances of relapse. The advent of novel targeted therapies and antibody-mediated treatments has proven revolutionary in the management of these tumors. Although these therapies have an added advantage of specificity in comparison to the traditional chemotherapy approach, such treatment alternatives suffer from the occurrence of drug resistance and dose-related toxicities. In past decades, nanomedicine has emerged as an excellent surrogate to increase the bioavailability of therapeutic moieties along with a reduction in toxicities of highly cytotoxic drugs. Nanotherapeutics achieve targeted delivery of the therapeutic agents into the malignant cells and also have the ability to carry genes and therapeutic proteins to the desired sites. Furthermore, nanomedicine has an edge in rendering personalized medicine as one type of lymphoma is pathologically different from others. In this review, we have highlighted various applications of nanotechnology-based delivery systems based on lipidic, polymeric and inorganic nanomaterials that address different targets for effectively tackling lymphomas. Moreover, we have discussed recent advances and therapies available exclusively for managing this malignancy.

Combining daratumumab with CD47 blockade prolongs survival in preclinical models of pediatric T-ALL

Acute lymphoblastic leukemia (ALL) is the most common malignant disease affecting children. Although therapy strategies improved, T-cell acute lymphoblastic leukemia (T-ALL) relapse is associated with chemoresistance and a poor prognosis. One strategy to overcome this obstacle is the application of monoclonal antibodies. Here, we show that leukemic cells from T-ALL patients express surface CD38 and CD47, both attractive targets for antibody therapy. We therefore investigated the commercially available CD38 antibody daratumumab (Dara) in combination with a proprietary modified CD47 antibody (Hu5F9-IgG2σ) in vitro and in vivo. Compared to single treatments, this combination significantly increased in vitro antibody-dependent cellular phagocytosis (ADCP) in T-ALL cell lines as well as in random de novo and in relapsed/refractory T-ALL patient derived xenograft (PDX) samples. Similarly, enhanced ADCP was observed when combining Dara with pharmacological inhibition of CD47 interactions using a glutaminyl cyclase inhibitor. Phase II-like preclinical in vivo trials using T-ALL PDX samples in experimental minimal residual disease like (MRD-like) and overt leukemia models revealed a high anti-leukemic efficacy of CD47 blockade alone. However, T-ALL xenograft mice subjected to chemotherapy first (post-chemo MRD) and subsequently co-treated with Dara and Hu5F9-IgG2σ displayed significantly reduced bone marrow infiltration as compared to single treatments. In relapsed and highly refractory T-ALL PDX combined treatment with Dara and Hu5F9-IgG2σ was required to substantially prolong survival as compared to single treatments. These findings suggest that combining CD47 blockade with Dara is a promising therapy for T-ALL, especially for relapsed/refractory disease harbouring a dismal prognosis in patients.

Novel treatment strategies for acetylcholine receptor antibody-positive myasthenia gravis and related disorders

The presence of autoantibodies directed against the muscle nicotinic acetylcholine receptor (AChR) is the most common cause of myasthenia gravis (MG). These antibodies damage the postsynaptic membrane of the neuromuscular junction and cause muscle weakness by depleting AChRs and thus impairing synaptic transmission. As one of the best-characterized antibody-mediated autoimmune diseases, AChR-MG has often served as a reference model for other autoimmune disorders. Classical pharmacological treatments, including broad-spectrum immunosuppressive drugs, are effective in many patients. However, complete remission cannot be achieved in all patients, and 10% of patients do not respond to currently used therapies. This may be attributed to production of autoantibodies by long-lived plasma cells which are resistant to conventional immunosuppressive drugs. Hence, novel therapies specifically targeting plasma cells might be a suitable therapeutic approach for selected patients. Additionally, in order to reduce side effects of broad-spectrum immunosuppression, targeted immunotherapies and symptomatic treatments will be required. This review presents established therapies as well as novel therapeutic approaches for MG and related conditions, with a focus on AChR-MG.

FK506-Binding Protein 11 Is a Novel Plasma Cell-Specific Antibody Folding Catalyst with Increased Expression in Idiopathic Pulmonary Fibrosis

Antibodies are central effectors of the adaptive immune response, widespread used therapeutics, but also potentially disease-causing biomolecules. Antibody folding catalysts in the plasma cell are incompletely defined. Idiopathic pulmonary fibrosis (IPF) is a fatal chronic lung disease with increasingly recognized autoimmune features. We found elevated expression of FK506-binding protein 11 (FKBP11) in IPF lungs where FKBP11 specifically localized to antibody-producing plasma cells. Suggesting a general role in plasma cells, plasma cell-specific FKBP11 expression was equally observed in lymphatic tissues, and in vitro B cell to plasma cell differentiation was accompanied by induction of FKBP11 expression. Recombinant human FKBP11 was able to refold IgG antibody in vitro and inhibited by FK506, strongly supporting a function as antibody peptidyl-prolyl cis-trans isomerase. Induction of ER stress in cell lines demonstrated induction of FKBP11 in the context of the unfolded protein response in an X-box-binding protein 1 (XBP1)-dependent manner. While deficiency of FKBP11 increased susceptibility to ER stress-mediated cell death in an alveolar epithelial cell line, FKBP11 knockdown in an antibody-producing hybridoma cell line neither induced cell death nor decreased expression or secretion of IgG antibody. Similarly, antibody secretion by the same hybridoma cell line was not affected by knockdown of the established antibody peptidyl-prolyl isomerase cyclophilin B. The results are consistent with FKBP11 as a novel XBP1-regulated antibody peptidyl-prolyl cis-trans isomerase and indicate significant redundancy in the ER-resident folding machinery of antibody-producing hybridoma cells.

Understanding the Bioactivity and Prognostic Implication of Commonly Used Surface Antigens in Multiple Myeloma

Multiple myeloma (MM) progression is dependent on its interaction with the bone marrow microenvironment and the immune system and is mediated by key surface antigens. Some antigens promote adhesion to the bone marrow matrix and stromal cells, while others are involved in intercellular interactions that result in differentiation of B-cells to plasma cells (PC). These interactions are also involved in malignant transformation of the normal PC to MM PC as well as disease progression. Here, we review selected surface antigens that are commonly used in the flow cytometry analysis of MM for identification of plasma cells (PC) and the discrimination between normal and malignant PC as well as prognostication. These include the markers: CD38, CD138, CD45, CD19, CD117, CD56, CD81, CD27, and CD28. Furthermore, we will discuss the novel marker CD24 and its involvement in MM. The bioactivity of each antigen is reviewed, as well as its expression on normal vs. malignant PC, prognostic implications, and therapeutic utility. Understanding the role of these specific surface antigens, as well as complex co-expressions of combinations of antigens, may allow for a more personalized prognostic monitoring and treatment of MM patients.

Regulation of CD38 on Multiple Myeloma and NK Cells by Monoclonal Antibodies

CD38 is highly expressed on multiple myeloma (MM) cells and plays a role in regulating tumor generation and development. CD38 monoclonal antibodies (mAbs) have been used as an effective therapy for MM treatment by various mechanisms, including complement-dependent cytotoxic effects, antibody-dependent cell-mediated cytotoxicity, antibody-dependent cellular phagocytosis, programmed cell death, enzymatic modulation, and immunomodulation. Although CD38 mAbs inhibit the proliferation and survival of MM cells, there are substantial side effects on antitumoral NK cells. The NK-mediated immune response needs to be further evaluated to minimize the adverse effects of NK cell loss. The killing effect of CD38 mAbs on CD38high NK cells should be minimized and the potential combination of CD38low/- NK cells and CD38 mAbs should be maximized to better benefit from their therapeutic efficacy against MM. CD38 mAb effects against MM can be maximized by combination therapies with immunomodulatory imide drugs (IMiDs), proteasome inhibitors (PIs), anti-programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) antibodies, or cellular therapies for the treatment of MM, especially in patients with relapsed or refractory MM (R/R MM) and drug-resistant MM.

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.

Recent Clinical Trials Insights into the Treatment of Primary Membranous Nephropathy

Immunosuppressive therapy is mandatory for primary membranous nephropathy with persistent nephrotic proteinuria or anti-phospholipase A2 receptor antibodies, reduced kidney function, or another risk factor for progression. Rituximab has demonstrated efficacy for proteinuria remission compared with renin-angiotensin system blockade or cyclosporine in two well-powered randomized controlled trials. More recently, STARMEN showed that alternating glucocorticoid-cyclophosphamide is superior to sequential tacrolimus-rituximab for proteinuria remission, although it was associated with a higher risk of non-serious adverse events. However, sequential tacrolimus-rituximab involved delayed lower dose rituximab and was the worst-performing rituximab regimen among those tested in randomized clinical trials. The RI-CYCLO pilot study did not demonstrate superiority of glucocorticoid-cyclophosphamide over rituximab and found no difference in adverse events. Overall, STARMEN and RI-CYCLO confirmed the efficacy of glucocorticoid-cyclophosphamide in patients with high-risk membranous nephropathy and the role of rituximab as a valid alternative. However, none of the trials tested an optimized rituximab protocol involving a second rituximab cycle before declaring treatment failure. Calcineurin inhibitors should be considered third-line drugs and sequential use of calcineurin inhibitor rituximab did not add over rituximab-only regimens. We critically review recent randomized controlled trials, propose a research agenda, and call for multinational pragmatic trials that enroll patients at referral centers to address unmet research needs.

TNB-738, a biparatopic antibody, boosts intracellular NAD+ by inhibiting CD38 ecto-enzyme activity

Cluster of differentiation 38 (CD38) is an ecto-enzyme expressed primarily on immune cells that metabolize nicotinamide adenine dinucleotide (NAD+) to adenosine diphosphate ribose or cyclic ADP-ribose and nicotinamide. Other substrates of CD38 include nicotinamide adenine dinucleotide phosphate and nicotinamide mononucleotide, a critical NAD+ precursor in the salvage pathway. NAD+ is an important coenzyme involved in several metabolic pathways and is a required cofactor for the function of sirtuins (SIRTs) and poly (adenosine diphosphate-ribose) polymerases. Declines in NAD+ levels are associated with metabolic and inflammatory diseases, aging, and neurodegenerative disorders. To inhibit CD38 enzyme activity and boost NAD+ levels, we developed TNB-738, an anti-CD38 biparatopic antibody that pairs two non-competing heavy chain-only antibodies in a bispecific format. By simultaneously binding two distinct epitopes on CD38, TNB-738 potently inhibited its enzymatic activity, which in turn boosted intracellular NAD+ levels and SIRT activities. Due to its silenced IgG4 Fc, TNB-738 did not deplete CD38-expressing cells, in contrast to the clinically available anti-CD38 antibodies, daratumumab, and isatuximab. TNB-738 offers numerous advantages compared to other NAD-boosting therapeutics, including small molecules, and supplements, due to its long half-life, specificity, safety profile, and activity. Overall, TNB-738 represents a novel treatment with broad therapeutic potential for metabolic and inflammatory diseases associated with NAD+ deficiencies.Abbreviations: 7-AAD: 7-aminoactinomycin D; ADCC: antibody dependent cell-mediated cytotoxicity; ADCP: antibody dependent cell-mediated phagocytosis; ADPR: adenosine diphosphate ribose; APC: allophycocyanin; cADPR: cyclic ADP-ribose; cDNA: complementary DNA; BSA: bovine serum albumin; CD38: cluster of differentiation 38; CDC: complement dependent cytotoxicity; CFA: Freund's complete adjuvant; CHO: Chinese hamster ovary; CCP4: collaborative computational project, number 4; COOT: crystallographic object-oriented toolkit; DAPI: 4',6-diamidino-2-phenylindole; DNA: deoxyribonucleic acid; DSC: differential scanning calorimetry; 3D: three dimensional; εNAD+: nicotinamide 1,N₆-ethenoadenine dinucleotide; ECD: extracellular domain; EGF: epidermal growth factor; FACS: fluorescence activated cell sorting; FcγR: Fc gamma receptors; FITC: fluorescein isothiocyanate; HEK: human embryonic kidney; HEPES: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; IgG: immunoglobulin; IFA: incomplete Freund's adjuvant; IFNγ: Interferon gamma; KB: kinetic buffer; kDa: kilodalton; KEGG: kyoto encyclopedia of genes and genomes; LDH: lactate dehydrogenase; M: molar; mM: millimolar; MFI: mean fluorescent intensity; NA: nicotinic acid; NAD: nicotinamide adenine dinucleotide; NADP: nicotinamide adenine dinucleotide phosphate; NAM: nicotinamide; NGS: next-generation sequencing; NHS/EDC: N-Hydroxysuccinimide/ ethyl (dimethylamino propyl) carbodiimide; Ni-NTA: nickel-nitrilotriacetic acid; nL: nanoliter; NK: natural killer; NMN: nicotinamide mononucleotide; OD: optical density; PARP: poly (adenosine diphosphate-ribose) polymerase; PBS: phosphate-buffered saline; PBMC: peripheral blood mononuclear cell; PDB: protein data bank; PE: phycoerythrin; PISA: protein interfaces, surfaces, and assemblies: PK: pharmacokinetics; mol: picomolar; RNA: ribonucleic acid; RLU: relative luminescence units; rpm: rotations per minute; RU: resonance unit; SEC: size exclusion chromatography; SEM: standard error of the mean; SIRT: sirtuins; SPR: surface plasmon resonance; µg: microgram; µM: micromolar; µL: microliter.

CD38-Directed Vincristine Nanotherapy for Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. Although intensive chemotherapy greatly improved the survival rate, it is often accompanied by severe and lifelong side effects as a result of weak ALL selectivity. The intensive and poorly selective chemotherapy is also detrimental to patients' immune system. There is an urgent need to develop more selective and less toxic chemotherapy for ALL. Here, we report daratumumab-polymersome-vincristine (DP-VCR) as a CD38-directed nanotherapy for ALL. DP-VCR showed selective uptake in CD38-positive 697 and Nalm-6-Luc ALL cells and potent anti-ALL activity with an IC₅₀ as low as 0.06 nM VCR, which was 13.7-fold more potent than free VCR. In contrast, no toxicity to human peripheral blood mononuclear cells was detected for DP-VCR even at 108.3 nM VCR. The apoptotic assays confirmed a high selectivity of DP-VCR to CD38-positive ALL cells. DP-VCR exhibited superior treatment of both 697 and Nalm-6-Luc orthotopic ALL models to all controls, as revealed by significant survival benefit and marked reduction of leukemia burden in bone marrow, blood, spleen, and liver. Importantly, DP-VCR induced few side effects. DP-VCR emerges as a safe and potent nanotherapy for CD38-positive ALL.

Review: Effects of anti-CD38 monoclonal antibodies on red blood cell transfusion and interventions

BACKGROUND

Highly expressed in almost all myeloma cells, CD38 is an attractive treatment target.

AIM

Anti-CD38 monoclonal antibodies have been approved for first-line treatment in non-transplantable multiple myeloma (MM) patients.

MATERIALS AND METHODS

However, it has been found in clinical use that anti-CD38 monoclonal antibodies bind to CD38 on red blood cells (RBCs) and cause panagglutination in indirect antiglobulin test (IAT), resulting in false positives of IAT (Transfusion, 55, 2015 and 1545; Transfusion, 55, 2015 and 1555).

RESULT

Thereby, interfering with blood bank testing and leading to the delay of further diagnosis and treatment.

CONCLUSION

With more and more patients receiving anti-CD38 treatment, it is of great importance to recognize this problem and optimize relevant diagnosis and treatment procedures to prevent RBC transfusion delays and reduce laboratory costs.

A Multi-Center Validated Subtyping Model of Esophageal Cancer Based on Three Metabolism-Related Genes

Metabolic reprogramming is a hallmark of malignancy. Understanding the characteristics of metabolic reprogramming in esophageal squamous cell carcinoma (ESCC) helps uncover novel targets for cancer progression. In this study, 880 metabolism-related genes were identified from microarray data and then filtered to divide patients into two subgroups using consensus clustering, which exhibits significantly different overall survival. After a differential analysis between two subtypes, 3 genes were screened out to construct a two subtypes decision model on the training cohort (GSE53624), defined as high-risk and low-risk subtypes. These risk models were then verified in two public databases (GSE53622 and TCGA-ESCC), an independent cohort of 49 ESCC patients by RT-qPCR and an external cohort of 95 ESCC patients by immunohistochemistry analysis (IHC). Furthermore, the immune cell infiltration of regulatory T cells (Tregs) and plasma cells showed a significant difference between the high and low-risk subtypes in the IHC experiment with 119 ESCC patients. In conclusion, our study indicated that three metabolism-related prognostic genes could stratify patients into subgroups and were associated with immune infiltration, clinical features and clinical outcomes.

Deciphering intratumoral heterogeneity using integrated clonal tracking and single-cell transcriptome analyses

Cellular heterogeneity is a major cause of treatment resistance in cancer. Despite recent advances in single-cell genomic and transcriptomic sequencing, it remains difficult to relate measured molecular profiles to the cellular activities underlying cancer. Here, we present an integrated experimental system that connects single cell gene expression to heterogeneous cancer cell growth, metastasis, and treatment response. Our system integrates single cell transcriptome profiling with DNA barcode based clonal tracking in patient-derived xenograft models. We show that leukemia cells exhibiting unique gene expression respond to different chemotherapies in distinct but consistent manners across multiple mice. In addition, we uncover a form of leukemia expansion that is spatially confined to the bone marrow of single anatomical sites and driven by cells with distinct gene expression. Our integrated experimental system can interrogate the molecular and cellular basis of the intratumoral heterogeneity underlying disease progression and treatment resistance.

DNA barcoding is a promising technology for the simultaneous analysis of genetic and phenotypic heterogeneity. Here, the authors combine DNA barcoding and single-cell RNA-seq to study heterogeneity, progression and response to therapy in B-cell acute lymphoblastic leukaemia patient-derived xenografts.

AL Amyloidosis: Current Chemotherapy and Immune Therapy Treatment Strategies: JACC: CardioOncology State-of-the-Art Review

Immunoglobulin light chain (AL) amyloidosis is an incurable plasma cell disorder characterized by deposition of fibrils of misfolded immunoglobulin free light chains (FLC) in target organs, leading to failure. Cardiac involvement is common in AL amyloidosis and represents the single most adverse prognostic feature. A high index of clinical suspicion with rapid tissue diagnosis and commencement of combinatorial, highly effective cytoreductive therapy is crucial to arrest the process of amyloid deposition and preserve organ function. The clinical use of molecularly targeted drugs, such as proteasome inhibitors and immunomodulatory agents, monoclonal antibodies such as daratumumab, and risk-adjusted autologous stem cell transplant in eligible patients, has radically changed the natural history of AL amyloidosis. Here, we review the state-of-the-art treatment landscape in AL amyloidosis with an eye toward future therapeutic venues to impact the outcome of this devastating illness.

Efficacy of first-line treatment options in transplant-ineligible multiple myeloma: A network meta-analysis

BACKGROUND

Despite major therapeutic advances, the rational choice of the most appropriate first-line regimen in newly diagnosed transplant-ineligible multiple myeloma (TIE-MM) is currently undefined.

AIM

We aimed to identify the most effective first-line treatment for TIE-MM patients.

METHODS

A total of 37 articles, including 34 treatments and 16,681 patients, were included in this Bayesian network meta-analysis. The outcomes of interest were risk ratios (RR) for progression-free survival (PFS) and overall survival (OS).

RESULTS

Based on surface under cumulative ranking curve values, daratumumab-bortezomib-melphalan-prednisone (Dara-VMP) and daratumumab-lenalidomide-dexamethasone (Dara-Rd28) showed superiority compared to other combinations regarding 12-, 24-, 36-, and 48-month PFS. Dara-VMP also ranked first for 12-, 24-, 36-, and 48-month OS.

CONCLUSION

Our finding supports the incorporation of daratumumab into first-line regimens. Additionally, these results highlight the relative benefit of incorporating novel agents like monoclonal antibodies, immunomodulatory derivatives, and proteasome inhibitors in combination with the currently existing treatment options.

Daratumumab May Attenuate Cardiac Dysfunction Related to Carfilzomib in Patients with Relapsed/Refractory Multiple Myeloma: A Prospective Study

Simple Summary

The management of cardiovascular adverse events in patients with relapsed/refractory multiple myeloma undergoing treatment with carfilzomib can be challenging. Herein, we evaluated the potential cardioprotective effect of daratumumab when administered in combination with carfilzomib and dexamethasone (DaraKd). The study included 25 patients receiving either DaraKd (n = 14) or Kd (n = 11) who were evaluated for echocardiographic changes at the sixth cycle of treatment compared with baseline assessment. DaraKd was associated with preserved post-treatment cardiac systolic function compared with Kd. CD38 inhibition by daratumumab might restore metabolic disequilibrium in the cardiac tissue and prevent cardiac injury. A trend for a lower rate of cardiovascular adverse events among patients receiving DaraKd was also evident, although larger studies are needed to determine the association between echocardiographic and/or biomarker changes with cardiovascular adverse events.

Abstract

Carfilzomib has improved survival in patients with relapsed/refractory multiple myeloma (RRMM), but it may exert cardiovascular adverse events (CVAEs). The aim of this study was to assess whether treatment with daratumumab may ameliorate carfilzomib-related toxicity. We prospectively evaluated 25 patients with RRMM who received either daratumumab in combination with carfilzomib and dexamethasone (DaraKd) (n = 14) or Kd (n = 11). Cardiac ultrasound was performed before treatment initiation and C6D16 or at the time of treatment interruption. Patients were followed for a median of 10 months for CVAEs. The mean (± SD) age was 67.8 ± 7.6 years and 60% were men. The two treatment groups did not significantly differ in baseline demographic characteristics (p > 0.1 for all). In the DaraKd group, we did not observe any significant change in markers of ventricular systolic function. However, these markers deteriorated in the Kd group; left ventricular (LV) ejection fraction, LV global longitudinal strain, tricuspid annular plane systolic excursion and RV free wall longitudinal strain significantly decreased from baseline to second visit (p < 0.05). A significant group interaction (p < 0.05) was observed for the abovementioned changes. CVAEs occurred more frequently in the Kd than the DaraKd group (45% vs. 28.6%). DaraKd was associated with preserved post-treatment cardiac systolic function and lower CVAE rate compared with Kd. The clinical significance and the underlying mechanisms merit further investigation.

Selective targeting of CD38 hydrolase and cyclase activity as an approach to immunostimulation

The ectoenzyme CD38 is highly expressed on the surface of mature immune cells, where they are a marker for cell activation, and also on the surface of multiple tumor cells such as multiple myeloma (MM). CD38-targeted monoclonal antibodies (MABs) such as daratumumab and isatuximab bind to CD38 and promote cancer cell death by stimulating the antitumor immune response. Although MABs are achieving unprecedented success in a percentage of cases, high rates of resistance limit their efficacy. Formation of the immunosuppressive intermediate adenosine is a major route by which this resistance is mediated. Thus there is an urgent need for small molecule agents that boost the immune response in T-cells. Importantly, CD38 is a dual-function enzyme, serving as a hydrolase and a nicotinamide adenine dinucleotide (NAD+) cyclase, and both of these activities promote immunosuppression. We have employed virtual and physical screening to identify novel compounds that are selective for either the hydrolase or the cyclase activity of CD38, and have demonstrated that these compounds activate T cells in vitro. We are currently optimizing these inhibitors for use in immunotherapy. These small molecule inhibitors of the CD38-hydrolase or cyclase activity can serve as chemical probes to determine the mechanism by which CD38 promotes resistance to MAB therapy, and could become novel and effective therapeutic agents that produce immunostimulatory effects. Our studies have identified the first small molecule inhibitors of CD38 specifically for use as immunostimulants.

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.

Fully human anti-CD39 antibody potently inhibits ATPase activity in cancer cells via uncompetitive allosteric mechanism

The extracellular ATP/adenosine axis in the tumor microenvironment (TME) has emerged as an important immune-regulatory pathway. Nucleoside triphosphate diphosphohydrolase-1 (NTPDase1), otherwise known as CD39, is highly expressed in the TME, both on infiltrating immune cells and tumor cells across a broad set of cancer indications. CD39 processes pro-inflammatory extracellular ATP to ADP and AMP, which is then processed by Ecto-5ʹ-nucleotidase/CD73 to immunosuppressive adenosine. Directly inhibiting the enzymatic function of CD39 via an antibody has the potential to unleash an immune-mediated anti-tumor response via two mechanisms: 1) increasing the availability of immunostimulatory extracellular ATP released by damaged and/or dying cells, and 2) reducing the generation and accumulation of suppressive adenosine within the TME. Tizona Therapeutics has engineered a novel first-in-class fully human anti-CD39 antibody, TTX-030, that directly inhibits CD39 ATPase enzymatic function with sub-nanomolar potency. Further characterization of the mechanism of inhibition by TTX-030 using CD39⁺ human melanoma cell line SK-MEL-28 revealed an uncompetitive allosteric mechanism (α < 1). The uncompetitive mechanism of action enables TTX-030 to inhibit CD39 at the elevated ATP concentrations reported in the TME. Maximal inhibition of cellular CD39 ATPase velocity was 85%, which compares favorably to results reported for antibody inhibitors to other enzyme targets. The allosteric mechanism of TTX-030 was confirmed via mapping the epitope to a region of CD39 distant from its active site, which suggests possible models for how potent inhibition is achieved. In summary, TTX-030 is a potent allosteric inhibitor of CD39 ATPase activity that is currently being evaluated in clinical trials for cancer therapy.

The EHA Research Roadmap: Immune-based Therapies for Hematological Malignancies

In 2016, the European Hematology Association (EHA) published the EHA Roadmap for European Hematology Research¹ aiming to highlight achievements in the diagnostics and treatment of blood disorders, and to better inform European policy makers and other stakeholders about the urgent clinical and scientific needs and priorities in the field of hematology. Each section was coordinated by 1-2 section editors who were leading international experts in the field. In the 5 years that have followed, advances in the field of hematology have been plentiful. As such, EHA is pleased to present an updated Research Roadmap, now including 11 sections, each of which will be published separately. The updated EHA Research Roadmap identifies the most urgent priorities in hematology research and clinical science, therefore supporting a more informed, focused, and ideally a more funded future for European Hematology Research. the 11 EHA Research Roadmap sections include normal hematopoiesis; malignant lymphoid diseases; malignant myeloid diseases; anemias and related diseases; platelet disorders; blood coagulation and hemostatic disorders; transfusion medicine; infections in hematology; hematopoietic stem cell transplantation; CAR-T and Other cell-based immune therapies; and gene therapy.

IDH2 contributes to tumorigenesis and poor prognosis by regulating m6A RNA methylation in multiple myeloma

Epigenetic alterations have been previously shown to contribute to multiple myeloma (MM) pathogenesis via DNA methylations and histone modifications. RNA methylation, a novel epigenetic modification, is required for cancer cell survival, and targeting this pathway has been proposed as a new therapeutic strategy. The extent to the N6-methyladenosine (m6A)-regulatory pathway functions in MM remains unknown. Here, we show that an imbalance of RNA methylation may underlies the tumorigenesis of MM. Mechanistically, isocitrate dehydrogenase 2 (IDH2) is highly expressed in CD138+ cells from MM and its levels appear a progressive increase in the progression of plasma cell dyscrasias. Downregulation of IDH2 increases global m6A RNA levels and reduces myeloma cell growth in vitro, decreases the burden of disease and prolongs overall survival in vivo. IDH2 regulates RNA methylation by activating the RNA demethylase FTO, which is an α-KG-dependent dioxygenase. Furthermore, IDH2-mediated FTO activation decreases the m6A level on WNT7B transcripts, then increases WNT7B expression and thus activated Wnt signaling pathway. Moreover, survival analysis indicates that the elevated expression of IDH2 predicts a poor prognosis. Higher expression of FTO is related to higher International Staging System (ISS) stage and higher Revised-ISS (R-ISS) stage of MM. Collectively, our studies reveal that IDH2 regulates global m6A RNA modification in MM via targeting RNA demethylases FTO. The imbalance of m6A methylation activates the Wnt signaling pathway by enhancing the WNT7B expression, and thus promoting tumorigenesis and progression of MM. IDH2 might be used as a therapeutic target and a possible prognostic factor for MM.

Evaluation of Preclinical Activity of Isatuximab in Patients with Acute Lymphoblastic Leukemia

This study reports the pharmacologic effects of isatuximab, a CD38 mAb, on T- and B-cell acute lymphoblastic leukemia (ALL). We analyzed CD38 expression in 50-T-ALL and 50 B-ALL clinical samples, and 16 T-ALL and 11 B-ALL cell lines. We primarily focused on in vitro assessments of isatuximab-mediated antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP). In vivo assessment of isatuximab activity was performed in several ALL xenograft models, including disseminated and subcutaneous tumor models in female C.B-17 severe combined immunodeficiency mice. Our study reveals that most patients (90%-100%) carried CD38⁺ blasts independent of disease burden. The median CD38 receptor density on abnormal lymphoblasts is 41,026 copies/cell on T-ALL and 28,137 copies/cell on B-ALL, respectively. In patients with T-ALL, there is a significant increase of CD38 expression in abnormal blasts compared with normal T cells. High-level CD38 receptor density (RD) is critical to trigger effective isatuximab-mediated ADCC against target ALL cells. In addition, a correlation between CD38 RD and isatuximab-mediated ADCP is demonstrated. In the disseminated CD38⁺, T-ALL, and B-ALL xenograft models, isatuximab is able to induce robust antitumor activity, even at low doses. This study shows that isatuximab has significant in vitro and in vivo activity against ALL cells with robust ADCC and ADCP effects that are associated with CD38 expression levels in both T-ALL and B-ALL.

Polymeric nanomedicines targeting hematological malignancies

Hematological malignancies (HMs) typically persisting in the blood, lymphoma, and/or bone marrow invalidate surgery and local treatments clinically used for solid tumors. The presence and drug resistance nature of cancer stem cells (CSCs) further lends HMs hard to cure. The development of new treatments like molecular targeted drugs and antibodies has improved the clinical outcomes for HMs but only to a certain extent, due to issues of low bioavailability, moderate response, occurrence of drug resistance, and/or dose-limiting toxicities. In the past years, polymeric nanomedicines targeting HMs including refractory and relapsed lymphoma, leukemia and multiple myeloma have emerged as a promising chemotherapeutic approach that is shown capable of overcoming drug resistance, delivering drugs not only to cancer cells but also CSCs, and increasing therapeutic index by lessening drug-associated adverse effects. In addition, polymeric nanomedicines have shown to potentiate next-generation anticancer modalities such as therapeutic proteins and nucleic acids in effectively treating HMs. In this review, we highlight recent advance in targeted polymeric nanoformulations that are coated with varying ligands (e.g. cancer cell membrane proteins, antibodies, transferrin, hyaluronic acid, aptamer, peptide, and folate) and loaded with different therapeutic agents (e.g. chemotherapeutics, molecular targeted drugs, therapeutic antibodies, nucleic acid drugs, and apoptotic proteins) for directing to distinct targets (e.g. CD19, CD20, CD22, CD30, CD38, CD44, CD64, CXCR, FLT3, VLA-4, and bone marrow microenvironment) in HMs. The advantages and potential challenges of different designs are discussed.

Stromal Cells Serve Drug Resistance for Multiple Myeloma via Mitochondrial Transfer: A Study on Primary Myeloma and Stromal Cells

Simple Summary

Mitochondrial transfer plays a crucial role in the acquisition of drug resistance in multiple myeloma, but its exact mechanism is not yet clear; moreover, overcoming the drug resistance that it causes is also a major challenge. Our research on primary myeloma cell cultures reveals that mitochondrial transfer is bi-directional between bone marrow stromal cells and myeloma cells, occurring via tunneling nanotubes and partial cell fusion with extreme increases under the influence of chemotherapeutic drugs, whereupon survival and adenosine triphosphate levels increase, while mitochondrial superoxide levels decrease in myeloma cells. These changes and the elevation of superoxide levels in stromal cells are proportional to the amount of incorporated mitochondria derived from the other cell type and to the concentration of the used drug. Although the inhibition of mitochondrial transfer is limited between stromal and myeloma cells, the supportive effect of stromal cells can be effectively averted by influencing the tumor metabolism with an inhibitor of oxidative phosphorylation in addition to chemotherapeutics.

Abstract

Recently, it has become evident that mitochondrial transfer (MT) plays a crucial role in the acquisition of cancer drug resistance in many hematologic malignancies; however, for multiple myeloma, there is a need to generate novel data to better understand this mechanism. Here, we show that primary myeloma cells (MMs) respond to an increasing concentration of chemotherapeutic drugs with an increase in the acquisition of mitochondria from autologous bone marrow stromal cells (BM-MSCs), whereupon survival and adenosine triphosphate levels of MMs increase, while the mitochondrial superoxide levels decrease in MMs. These changes are proportional to the amount of incorporated BM-MSC-derived mitochondria and to the concentration of the used drug, but seem independent from the type and mechanism of action of chemotherapeutics. In parallel, BM-MSCs also incorporate an increasing amount of MM cell-derived mitochondria accompanied by an elevation of superoxide levels. Using the therapeutic antibodies Daratumumab, Isatuximab, or Elotuzumab, no similar effect was observed regarding the MT. Our research shows that MT occurs via tunneling nanotubes and partial cell fusion with extreme increases under the influence of chemotherapeutic drugs, but its inhibition is limited. However, the supportive effect of stromal cells can be effectively avoided by influencing the metabolism of myeloma cells with the concomitant use of chemotherapeutic agents and an inhibitor of oxidative phosphorylation.

Mechanisms of Action of the New Antibodies in Use in Multiple Myeloma

Monoclonal antibodies (mAbs) directed against antigen-specific of multiple myeloma (MM) cells have Fc-dependent immune effector mechanisms, such as complement-dependent cytotoxicity (CDC), antibody-dependent cellular cytotoxicity (ADCC), and antibody-dependent cellular phagocytosis (ADCP), but the choice of the antigen is crucial for the development of effective immuno-therapy in MM. Recently new immunotherapeutic options in MM patients have been developed against different myeloma-related antigens as drug conjugate-antibody, bispecific T-cell engagers (BiTEs) and chimeric antigen receptor (CAR)-T cells. In this review, we will highlight the mechanism of action of immuno-therapy currently available in clinical practice to target CD38, SLAMF7, and BCMA, focusing on the biological role of the targets and on mechanisms of actions of the different immunotherapeutic approaches underlying their advantages and disadvantages with critical review of the literature data.

PK/PD modeling analysis for dosing regimen selection of isatuximab as single agent and in combination therapy in patients with multiple myeloma

This analysis describes the pharmacokinetic/pharmacodynamic (PK/PD) modeling framework that supported selection of the isatuximab (anti‐CD38 monoclonal antibody) dosing regimen alongside its early clinical development in patients with relapsed/refractory multiple myeloma (RRMM). The PK/PD mathematical model characterized the variations of patient serum M‐protein concentrations, the primary marker of tumor burden in multiple myeloma (MM). Three separate PK/PD models were built sequentially as data became available from phase I clinical trials. The primary PK/PD analysis was initiated using monotherapy phase I study data (n = 122), followed by analysis of data collected from phase Ib combination studies with lenalidomide and dexamethasone (Rd, n = 40) and then with pomalidomide and dexamethasone (Pd, n = 31). Using the PK/PD model, abnormal “myeloma” protein (M‐protein) profiles under different isatuximab dosing regimens were simulated. Overall, simulations revealed that regimens which included a loading period of four weekly administrations followed by administration every 2 weeks thereafter (QW4‐Q2W), reduced M‐protein levels more than a Q2W regimen without a loading period. For isatuximab monotherapy, a 20 mg/kg dose induced greater reduction in serum M‐protein levels compared with doses equal or lower than 10 mg/kg. For isatuximab in combination with either Rd or Pd, simulations yielded no substantial benefit in terms of M‐protein reduction between isatuximab 10 mg/kg and 20 mg/kg. These PK/PD analyses supported the use of isatuximab 10 mg/kg QW4‐Q2W in combination with Pd in the phase III trial.

Antigen Loss after Targeted Immunotherapy in Hematological Malignancies

Immunotherapy marked a milestone in cancer treatment and has shown unprecedented efficacy in a variety of hematological malignancies. Downregulation or loss of target antigens is commonly seen after immunotherapy, which often causes diagnostic dilemma and represents a key mechanism that tumor escapes from immunotherapy. The awareness of phenotypic changes after targeted immunotherapy is important to avoid misdiagnosis. Further understanding of the mechanisms of antigen loss is paramount for the development of therapeutic approaches that can prevent or overcome antigen escape in future immunotherapy.

Orthogonal targeting of osteoclasts and myeloma cells for radionuclide stimulated dynamic therapy induces multidimensional cell death pathways

Rationale: Multiple myeloma (MM) is a multifocal malignancy of bone marrow plasma cells, characterized by vicious cycles of remission and relapse that eventually culminate in death. The disease remains mostly incurable largely due to the complex interactions between the bone microenvironment (BME) and MM cells (MMC). In the “vicious cycle” of bone disease, abnormal activation of osteoclasts (OCs) by MMC causes severe osteolysis, promotes immune evasion, and stimulates the growth of MMC. Disrupting these cancer-stroma interactions would enhance treatment response.

Methods: To disrupt this cycle, we orthogonally targeted nanomicelles (NM) loaded with non-therapeutic doses of a photosensitizer, titanocene (TC), to VLA-4 (α4ß1, CD49d/CD29) expressing MMC (MM1.S) and αvß3 (CD51/CD61) expressing OC. Concurrently, a non-lethal dose of a radiopharmaceutical, ¹⁸F-fluorodeoxyglucose ([¹⁸F]FDG) administered systemically interacted with TC (radionuclide stimulated therapy, RaST) to generate cytotoxic reactive oxygen species (ROS). The in vitro and in vivo effects of RaST were characterized in MM1.S cell line, as well as in xenograft and isograft MM animal models.

Results: Our data revealed that RaST induced non-enzymatic hydroperoxidation of cellular lipids culminating in mitochondrial dysfunction, DNA fragmentation, and caspase-dependent apoptosis of MMC using VLA-4 avid TC-NMs. RaST upregulated the expression of BAX, Bcl-2, and p53, highlighting the induction of apoptosis via the BAK-independent pathway. The enhancement of multicopper oxidase enzyme F5 expression, which inhibits lipid hydroperoxidation and Fenton reaction, was not sufficient to overcome RaST-induced increase in the accumulation of irreversible function-perturbing α,ß-aldehydes that exerted significant and long-lasting damage to both DNA and proteins. In vivo, either VLA-4-TC-NM or αvß3-TC-NMs RaST induced a significant therapeutic effect on immunocompromised but not immunocompetent MM-bearing mouse models. Combined treatment with both VLA-4-TC-NM and αvß3-TC-NMs synergistically inhibited osteolysis, reduced tumor burden, and prevented rapid relapse in both in vivo models of MM.

Conclusions: By targeting MM and bone cells simultaneously, combination RaST suppressed MM disease progression through a multi-prong action on the vicious cycle of bone cancer. Instead of using the standard multidrug approach, our work reveals a unique photophysical treatment paradigm that uses nontoxic doses of a single light-sensitive drug directed orthogonally to cancer and bone cells, followed by radionuclide-stimulated generation of ROS to inhibit tumor progression and minimize osteolysis in both immunocompetent murine and immunocompromised human MM models.

Pathophysiology and Therapeutic Approaches to Cardiac Amyloidosis

Often considered a rare disease, cardiac amyloidosis is increasingly recognized by practicing clinicians. The increased rate of diagnosis is in part due the aging of the population and increasing incidence and prevalence of cardiac amyloidosis with advancing age, as well as the advent of noninvasive methods using nuclear scintigraphy to diagnose transthyretin cardiac amyloidosis due to either variant or wild type transthyretin without a biopsy. Perhaps the most important driver of the increased awareness is the elucidation of the biologic mechanisms underlying the pathogenesis of cardiac amyloidosis which have led to the development of several effective therapies with differing mechanisms of actions. In this review, the mechanisms underlying the pathogenesis of cardiac amyloidosis due to light chain (AL) or transthyretin (ATTR) amyloidosis are delineated as well as the rapidly evolving therapeutic landscape that has emerged from a better pathophysiologic understanding of disease development.

Investigational treatment options in phase I and phase II trials for relapsed or refractory acute lymphoblastic leukemia in pediatric patients

Introduction: Upfront treatment of pediatric patients with B-cell acute lymphoblastic leukemia (B-ALL) and T-cell acute lymphoblastic leukemia (T-ALL) results in cure rates of 60-95%, depending on risk factors. However, patients with refractory or relapsed B-ALL or T-ALL have much worse outcomes with conventional chemotherapy, hence treatment of these cohorts with novel agents is a priority.Areas Covered: This paper reviews early phase clinical trials in pediatric leukemia. Investigational antibody therapy, chimeric antigen receptor T-cell (CAR-T), and other targeted therapies are examined. The authors discuss the mechanisms of action, side effects, trial designs, and outcomes and reflect on potential research directions. PubMed and Clinicaltrials.gov were searched from 2010 to present, using keywords 'lymphoblastic leukemia' with filters for pediatric age, Phase 1 clinical trial and Phase 2 clinical trial.Expert Opinion: Pediatric patients with relapsed or refractory leukemia often do not derive additional benefit from intensified conventional chemotherapy approaches which have arguably been maximized in the upfront setting. Therefore, novel approaches, such as immunotherapy and targeted agents should be prioritized. Progress will require commitment from pharmaceutical companies regarding these orphan diagnoses and acknowledgment from regulatory bodies that outcomes are suboptimal with conventional chemotherapy.

Pulsatilla saponin A Induces Apoptosis and Differentiation of Myeloma Cells

OBJECTIVES

To investigate the performance of Pulsatilla saponin A (PsA) in Multiple Myeloma (MM) cells.

METHODS

Proliferation, cell cycle analysis, apoptosis and TUNEL assays were conducted to detect the growth and apoptosis in MM cells. Western blotting was used to identify the change in the protein.

RESULTS

In cell assays, PsA significantly inhibited the growth and apoptosis in MM cells. Cyclin B1, caspase-3, cleaved-caspase-3, PARP, cleaved-PARP, p-ERK increased, while Bcl-2 decreased after PSA treatment. The CD49e positive rate of U266 cells was increased after 96h PsA treatment. At the same time, immunoglobulin and the Free Light Chain (FLC) ratio in the culture supernatant obviously increased. Also, the differentiation induced by PsA was confirmed in the primary myeloma cells.

CONCLUSION

Our findings reveal that PsA may exert its antitumor effect by causing G2 arrest and apoptosis in myeloma cells. And low-dose PsA can induce the differentiation of myeloma cell lines and primary myeloma cells, probably through the MEK/ERK signaling pathway in vitro.

The role of CD38 in HIV infection

The widely-expressed molecule CD38 is a single-stranded type II transmembrane glycoprotein that is mainly involved in regulating the differentiation and activation state of the cell. CD38 has broad and complex functions, including enzymatic activity, intercellular signal transduction, cell activation, cytokine production, receptor function and adhesion activity, and it plays an important role in the physiological and pathological processes of many diseases. Many studies have shown that CD38 is related to the occurrence and development of HIV infection, and CD38 may regulate its progression through different mechanisms. Therefore, investigating the role of CD38 in HIV infection and the potential signaling pathways that are involved may provide a new perspective on potential treatments for HIV infection. In the present review, the current understanding of the roles CD38 plays in HIV infection are summarized. In addition, the specific role of CD38 in the process of HIV infection of human CD4⁺ T lymphocytes is also discussed.

CD38 deletion of human primary NK cells eliminates daratumumab-induced fratricide and boosts their effector activity

Multiple myeloma (MM) is a plasma cell neoplasm that commonly expresses CD38. Daratumumab (DARA), a human monoclonal antibody targeting CD38, has significantly improved the outcome of patients with relapsed or refractory MM, but the response is transient in most cases. Putative mechanisms of suboptimal efficacy of DARA include downregulation of CD38 expression and overexpression of complement inhibitory proteins on MM target cells as well as DARA-induced depletion of CD38high natural killer (NK) cells resulting in crippled antibody-dependent cellular cytotoxicity (ADCC). Here, we tested whether maintaining NK cell function during DARA therapy could maximize DARA-mediated ADCC against MM cells and deepen the response. We used the CRISPR/Cas9 system to delete CD38 (CD38KO) in ex vivo expanded peripheral blood NK cells. These CD38KO NK cells were completely resistant to DARA-induced fratricide, showed superior persistence in immune-deficient mice pretreated with DARA, and enhanced ADCC activity against CD38-expressing MM cell lines and primary MM cells. In addition, transcriptomic and cellular metabolic analysis demonstrated that CD38KO NK cells have unique metabolic reprogramming with higher mitochondrial respiratory capacity. Finally, we evaluated the impact of exposure to all-trans retinoic acid (ATRA) on wild-type NK and CD38KO NK cell function and highlighted potential benefits and drawbacks of combining ATRA with DARA in patients with MM. Taken together, these findings provide proof of concept that adoptive immunotherapy using ex vivo expanded CD38KO NK cells has the potential to boost DARA activity in MM.

Antibody-Based Treatment Approaches in Multiple Myeloma

PURPOSE OF REVIEW

The field of multiple myeloma treatment has entered a new era with antibody-based approaches in clinical practice. In this review, we focus on the clinical approaches of utilizing antibody-based modality, specifically monoclonal antibodies, antibody-drug conjugates, and bispecific T-cell antibodies in the treatment of multiple myeloma.

RECENT FINDINGS

Three monoclonal antibodies (daratumumab, isatuximab, elotuzumab) and one anti-BCMA (B-cell maturation antigen) antibody-drug conjugate (belantamab mafodotin) have been approved by the FDA in the last 5 years for the treatment of multiple myeloma. There are many ongoing clinical trials using novel targets and constructs, including bispecific antibodies against BCMA, GPRC5D, and FCRH5. In addition to exploring efficacy, there are ongoing efforts to overcome the resistance to therapy. Antibody-based therapy has improved the outcomes of patients with multiple myeloma and has been incorporated in the standard of care. We expect to see novel targets and constructs that can achieve a deeper and more durable response while minimizing toxicity, as well as better strategies for toxicity management for existing agents. We also expect that antibody-based strategies will be used in earlier lines of therapy in the future.

Isatuximab plus pomalidomide and dexamethasone in patients with relapsed/refractory multiple myeloma according to prior lines of treatment and refractory status: ICARIA-MM subgroup analysis

Patients with relapsed/refractory multiple myeloma (RRMM) experience several relapses, and become refractory to successive therapies. In the ICARIA-MM trial (NCT02990338), isatuximab plus pomalidomide-dexamethasone prolonged median progression-free survival (PFS) in patients with RRMM. This subgroup analysis of ICARIA-MM assessed the treatment benefit of isatuximab by prior lines of therapy and refractory status. A total of 307 patients were randomized to isatuximab-pomalidomide-dexamethasone (n = 154) or pomalidomide-dexamethasone (n = 153). Isatuximab (10 mg/kg intravenously) was given weekly in the first 28-day cycle, then every other week. Standard pomalidomide-dexamethasone doses were given. PFS was assessed by prior lines and refractory status. Overall, 102 (66 %) patients receiving isatuximab-pomalidomide-dexamethasone and 101 (66 %) patients receiving pomalidomide-dexamethasone had received 2-3 prior lines; 52 (34 %) and 52 (34 %) had received >3 prior lines, respectively. Median PFS was higher with isatuximab-pomalidomide-dexamethasone versus pomalidomide-dexamethasone for patients who received 2-3 prior lines of therapy (12.3 vs. 7.8 months) and >3 prior lines of therapy (9.4 vs. 4.3 months). Median PFS was higher with isatuximab-pomalidomide-dexamethasone versus pomalidomide-dexamethasone for patients who were lenalidomide-refractory (11.4 vs. 5.6 months), lenalidomide-refractory at last line (11.6 vs. 5.7 months), refractory to a proteasome inhibitor (PI) (11.4 vs. 5.6 months), and double-refractory (11.2 vs. 4.8 months). Overall response rate (ORR) in patients receiving isatuximab-pomalidomide-dexamethasone versus pomalidomide-dexamethasone was 59.0 % versus 31.4 % in lenalidomide-refractory; 60.2 % versus 32.2 % in PI-refractory; and 58.6 % versus 29.9 % in double-refractory patients. Isatuximab-pomalidomide-dexamethasone improved PFS and ORR regardless of prior lines of therapy or refractory status, consistent with the benefit in the overall population.

Flow cytometric evaluation of CD38 expression levels in the newly diagnosed T-cell acute lymphoblastic leukemia and the effect of chemotherapy on its expression in measurable residual disease, refractory disease and relapsed disease: an implication for anti-CD38 immunotherapy

Background

Recently, anti-CD38 monoclonal antibody (Mab) therapy has become a focus of attention as an additional/alternative option for many hematological neoplasms including T-cell acute lymphoblastic leukemia (T-ALL). It has been shown that antitumor efficacy of anti-CD38-Mab depends on the level of CD38 expression on tumor cells. Reports on CD38 expression in T-ALL are scarce, and data on the effect of cytotoxic chemotherapy on CD38 expression are limited to very few samples. Moreover, it lacks entirely in refractory disease and in adult T-ALL. We report the flow cytometric evaluation of CD38 expression in T-ALL blasts at diagnosis and the effect of cytotoxic chemotherapy on its expression in measurable residual disease (MRD), refractory disease (MRD≥5%), and relapsed disease in a large cohort of T-ALL.

Methods

The study included 347 samples (188 diagnostic, 100 MRD, 24 refractory and 35 relapse samples) from 196 (children: 85; adolescents/adults: 111) patients with T-ALL. CD38-positive blasts percentages (CD38-PBPs) and expression-intensity (mean fluorescent intensity, CD38-MFI) were studied using multicolor flow cytometry (MFC). MFC-based MRD was performed at the end-of-induction (EOI-MRD, day 30–35) and end-of-consolidation (EOC-MRD, day 78–85) subsequent follow-up (SFU-MRD) points.

Results

Patients were classified into early thymic precursor subtype of T-ALL (ETPALL, 54/188, 28.7%), and non-ETPALL (134/188, 71.3%). Of 188, EOI-MRD assessment was available in 152, EOC-MRD was available in 96 and SFU-MRD was available in 14 patients. CD38 was found positive in 97.9% (184/188) of diagnostic, 88.7% (110/124) MRD (including 24-refractory) and 82.9% (29/35) relapsed samples. Median (95% CI) of CD38-PBPs/MFI in diagnostic, MRD, refractory, and relapsed T-ALL samples were, respectively, 85.9% (82.10%–89.91%)/4.2 (3.88–4.47), 74.0% (58.87%–83.88%)/4.6 (3.67–6.81), 79.6% (65.25%–96.11%)/4.6 (3.33–8.47) and 85.2% (74.48%–93.01%)/5.6 (4.14–8.99). No significant difference was noted in CD38 expression between pediatric versus adult and patients with ETPALL versus non-ETPALL. No change was observed in CD38-MFI between diagnostic versus MRD and diagnostic versus relapsed paired samples. However, we noticed a mild drop in the CD38-PBPs in MRD samples compared with the diagnostic samples (p=0.016).

Conclusion

We report an in-depth analysis of CD38 expression in a large cohort of T-ALL at diagnosis, during chemotherapy, and at relapse. Our data demonstrated that CD38 is robustly expressed in T-ALL blasts with a little effect of cytotoxic chemotherapy making it a potentially effective target for antiCD38-Mab therapy.