CS1-directed monoclonal antibody therapy for multiple myeloma

Latest Advances for the Sleeping Beauty Transposon System: 23 Years of Insomnia but Prettier than Ever: Refinement and Recent Innovations of the Sleeping Beauty Transposon System Enabling Novel, Nonviral Genetic Engineering Applications

The Sleeping Beauty transposon system is a nonviral DNA transfer tool capable of efficiently mediating transposition-based, stable integration of DNA sequences of choice into eukaryotic genomes. Continuous refinements of the system, including the emergence of hyperactive transposase mutants and novel approaches in vectorology, greatly improve upon transposition efficiency rivaling viral-vector-based methods for stable gene insertion. Current developments, such as reversible transgenesis and proof-of-concept RNA-guided transposition, further expand on possible applications in the future. In addition, innate advantages such as lack of preferential integration into genes reduce insertional mutagenesis-related safety concerns while comparably low manufacturing costs enable widespread implementation. Accordingly, the system is recognized as a powerful and versatile tool for genetic engineering and is playing a central role in an ever-expanding number of gene and cell therapy clinical trials with the potential to become a key technology to meet the growing demand for advanced therapy medicinal products.

CAR-NK cell therapeutics for hematologic malignancies: hope is on the horizon

Chimeric antigen receptor (CAR)-T-cell therapy has achieved significant success in the treatment of hematologic malignancies. However, treatment-related toxicity and side effects remain the major drawbacks. As an important effector cell in innate immunity, natural killer (NK) cells exert strong antitumor functions and have better application prospects in the immunotherapy of hematologic malignancies. Compared with T cells, NK cells exhibit several advantages such as MHC-independent recognition. CAR-modified NK (CAR-NK) cells may exhibit a better ability of killing tumor cells. Herein, we review mainly preclinical data related to the development of CAR-NK cells in treating blood cancers.

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.

SLAMF7-CAR T cells eliminate myeloma and confer selective fratricide of SLAMF7+ normal lymphocytes

SLAMF7 is under intense investigation as a target for immunotherapy in multiple myeloma. In this study, we redirected the specificity of T cells to SLAMF7 through expression of a chimeric antigen receptor (CAR) derived from the huLuc63 antibody (elotuzumab) and demonstrate that SLAMF7-CAR T cells prepared from patients and healthy donors confer potent antimyeloma reactivity. We confirmed uniform, high-level expression of SLAMF7 on malignant plasma cells in previously untreated and in relapsed/refractory (R/R) myeloma patients who had received previous treatment with proteasome inhibitors and immunomodulatory drugs. Consequently, SLAMF7-CAR T cells conferred rapid cytolysis of previously untreated and R/R primary myeloma cells in vitro. In addition, a single administration of SLAMF7-CAR T cells led to resolution of medullary and extramedullary myeloma manifestations in a murine xenograft model in vivo. SLAMF7 is expressed on a fraction of normal lymphocytes, including subsets of natural killer (NK) cells, T cells, and B cells. After modification with the SLAMF7-CAR, both CD8⁺ and CD4⁺ T cells rapidly acquired and maintained a SLAMF7^- phenotype and could be readily expanded to therapeutically relevant cell doses. We analyzed the recognition of normal lymphocytes by SLAMF7-CAR T cells and show that they induce selective fratricide of SLAMF7^+/high NK cells, CD4⁺ and CD8⁺ T cells, and B cells. Importantly, however, the fratricide conferred by SLAMF7-CAR T cells spares the SLAMF7^-/low fraction in each cell subset and preserves functional lymphocytes, including virus-specific T cells. In aggregate, our data illustrate the potential use of SLAMF7-CAR T-cell therapy as an effective treatment against multiple myeloma and provide novel insights into the consequences of targeting SLAMF7 for the normal lymphocyte compartment.

A compound chimeric antigen receptor strategy for targeting multiple myeloma

Current clinical outcomes using chimeric-antigen receptors (CARs) against multiple myeloma show promise in the eradication of bulk disease. However, these anti-BCMA (CD269) CARs observe relapse as a common phenomenon after treatment due to the reemergence of either antigen-positive or -negative cells. Hence, the development of improvements in CAR design to target antigen loss and increase effector cell persistency represents a critical need. Here, we report on the anti-tumor activity of a CAR T-cell possessing two complete and independent CAR receptors against the multiple myeloma antigens BCMA and CS1. We determined that the resulting compound CAR (cCAR) T-cell possesses consistent, potent and directed cytotoxicity against each target antigen population. Using multiple mouse models of myeloma and mixed cell populations, we are further able to show superior in vivo survival by directed cytotoxicity against multiple populations compared to a single-expressing CAR T-cell. These findings indicate that compound targeting of BCMA and CS1 on myeloma cells can potentially be an effective strategy for augmenting the response against myeloma bulk disease and for initiation of broader coverage CAR therapy.

How to Integrate Elotuzumab and Daratumumab Into Therapy for Multiple Myeloma

Purpose Treatment options and outcomes for patients with multiple myeloma have dramatically improved over the past decade with new agents and drug targets for patients at all stages of disease. Incorporation of newly approved monoclonal antibodies is a clinical challenge because the trials used to gain approval are relatively limited in scope and may be less helpful for patients treated in the United States. This article will review data on the use of elotuzumab and daratumumab and provide a foundation for their use in current clinical practice. Methods We performed a review of current published articles and abstract data from clinical trials as well as data on managing adverse events. Results Single-agent activity was seen when using daratumumab in refractory myeloma, and trials for both elotuzumab and daratumumab have demonstrated significant activity when combined with proteasome inhibitors and immunomodulatory agents. Unique antibody-related adverse events and challenges are reviewed and discussed. Conclusion These antibodies already have had and will continue to have a dramatic impact on myeloma treatment. Combination therapy likely represents the best approach for their use, and trials that evaluate optimal timing and duration of therapy are in progress as part of induction, salvage, and maintenance therapy.

Monoclonal antibody therapy in multiple myeloma: where do we stand and where are we going?

Multiple myeloma is a plasma cell malignancy that is characterized by refractory and relapsing course of disease. Despite the introduction of high-dose chemotherapy in combination with autologous stem cell transplantation and innovative agents such as proteasome inhibitors and immunomodulatory drugs, achieving cure in multiple myeloma is a challenging endeavor. In the last couple of years, enormous advances were made in implementing monoclonal antibody therapy in multiple myeloma. A large number of preclinical and clinical studies have been introduced successfully, demonstrating a safe and efficient administration of monoclonal antibodies in multiple myeloma. In particular, the application of monoclonal antibodies in combination with immunomodulatory drugs, proteasome inhibitors, corticosteroids or conventional chemotherapy seem to be promising and will expand the treatment arsenal for patients with multiple myeloma.

Present and Future of Allogeneic Natural Killer Cell Therapy

Natural killer (NK) cells are innate lymphocytes that are capable of eliminating tumor cells and are therefore used for cancer therapy. Although many early investigators used autologous NK cells, including lymphokine-activated killer cells, the clinical efficacies were not satisfactory. Meanwhile, human leukocyte antigen (HLA)-haploidentical hematopoietic stem cell transplantation revealed the antitumor effect of allogeneic NK cells, and HLA-haploidentical, killer cell immunoglobulin-like receptor ligand-mismatched allogeneic NK cells are currently used for many protocols requiring NK cells. Moreover, allogeneic NK cells from non-HLA-related healthy donors have been recently used in cancer therapy. The use of allogeneic NK cells from non-HLA-related healthy donors allows the selection of donor NK cells with higher flexibility and to prepare expanded, cryopreserved NK cells for instant administration without delay for ex vivo expansion. In cancer therapy with allogeneic NK cells, optimal matching of donors and recipients is important to maximize the efficacy of the therapy. In this review, we summarize the present state of allogeneic NK cell therapy and its future directions.

A Phase I Trial of the Anti-KIR Antibody IPH2101 and Lenalidomide in Patients with Relapsed/Refractory Multiple Myeloma

PURPOSE

Natural killer (NK) cells may play an important role in the immune response to multiple myeloma; however, multiple myeloma cells express killer immunoglobulin-like receptor (KIR) ligands to prevent NK cell cytotoxicity. Lenalidomide can expand and activate NK cells in parallel with its direct effects against multiple myeloma; however, dexamethasone may impair these favorable immunomodulatory properties. IPH2101, a first-in-class antiinhibitory KIR antibody, has acceptable safety and tolerability in multiple myeloma as a single agent. The present work sought to characterize lenalidomide and IPH2101 as a novel, steroid-sparing, dual immune therapy for multiple myeloma.

EXPERIMENTAL DESIGN

A phase I trial enrolled 15 patients in three cohorts. Lenalidomide was administered per os at 10 mg on cohort 1 and 25 mg on cohorts 2 and 3 days 1 to 21 on a 28-day cycle with IPH2101 given intravenously on day 1 of each cycle at 0.2 mg/kg in cohort 1, 1 mg/kg in cohort 2, and 2 mg/kg in cohort 3. No corticosteroids were utilized. The primary endpoint was safety, and secondary endpoints included clinical activity, pharmacokinetics (PK), and pharmacodynamics (PD).

RESULTS

The biologic endpoint of full KIR occupancy was achieved across the IPH2101 dosing interval. PD and PK of IPH2101 with lenalidomide were similar to data from a prior single-agent IPH2101 trial. Five serious adverse events (SAE) were reported. Five objective responses occurred. No autoimmunity was seen.

CONCLUSIONS

These findings suggest that lenalidomide in combination with antiinhibitory KIR therapy warrants further investigation in multiple myeloma as a steroid-sparing, dual immune therapy. This trial was registered at www.clinicaltrials.gov (reference: NCT01217203).

Cellular immunotherapy in multiple myeloma: lessons from preclinical models

The majority of multiple myeloma patients relapse with the current treatment strategies, raising the need for alternative therapeutic approaches. Cellular immunotherapy is a rapidly evolving field and currently being translated into clinical trials with encouraging results in several cancer types, including multiple myeloma. Murine multiple myeloma models are of critical importance for the development and refinement of cellular immunotherapy. In this review, we summarize the immune cell changes that occur in multiple myeloma patients and we discuss the cell-based immunotherapies that have been tested in multiple myeloma, with a focus on murine models.

Genetic modification of T cells redirected toward CS1 enhances eradication of myeloma cells

PURPOSE

Our goal is to test whether CS1 could be targeted by chimeric antigen receptor (CAR) T cells to treat multiple myeloma (MM).

EXPERIMENTAL DESIGN

We generated a retroviral construct of a CS1-specific CAR and engineered primary human T cells expressing the CAR. We then tested the capacity of CS1-CAR T cells to eradicate human MM tumor cells in vitro, ex vivo, and in vivo using orthotopic MM xenograft mouse models.

RESULTS

In vitro, compared with mock-transduced T cells, upon recognizing CS1-positive MM cells, CS1-CAR-transduced T cells secreted more IFN-γ as well as interleukin (IL)-2, expressed higher levels of the activation marker CD69, showed higher capacity for degranulation, and displayed enhanced cytotoxicity. Ectopically forced expression of CS1 in MM cells with low CS1 expression enhanced recognition and killing by CAR T cells. Ex vivo, CS1-CAR T cells also showed similarly enhanced activities when responding to primary MM cells. More importantly, in orthotopic MM xenograft mouse models, adoptive transfer of human primary T cells expressing CS1-CAR efficiently suppressed the growth of human MM.1S and IM9 myeloma cells and significantly prolonged mouse survival.

CONCLUSIONS

CS1 is a promising antigen that can be targeted by CAR-expressing T cells for treatment of MM.

Combination immune therapies to enhance anti-tumor responses by NK cells

Natural killer (NK) cells are critical innate immune lymphocytes capable of destroying virally infected or cancerous cells through targeted cytotoxicity and further assisting in the immune response by releasing inflammatory cytokines. NK cells are thought to contribute to the process of tumor killing by certain therapeutic monoclonal antibodies (mAb) by directing antibody-dependent cellular cytotoxicity (ADCC) through FcγRIIIA (CD16). Numerous therapeutic mAb have been developed that target distinct cancer-specific cell markers and may direct NK cell-mediated ADCC. Recent therapeutic approaches have combined some of these cancer-specific mAb with additional strategies to optimize NK cell cytotoxicity. These include agonistic mAb targeting NK cell activating receptors and mAbs blocking NK cell inhibitory receptors to enhance NK cell functions. Furthermore, several drugs that can potentiate NK cell cytotoxicity through other mechanisms are being used in combination with therapeutic mAb. In this review, we examine the mechanisms employed by several promising agents used in combination therapies that enhance natural or Ab-dependent cytotoxicity of cancer cells by NK cells, with a focus on treatments for leukemia and multiple myeloma.

CS1-specific chimeric antigen receptor (CAR)-engineered natural killer cells enhance in vitro and in vivo antitumor activity against human multiple myeloma

Multiple myeloma (MM) is an incurable hematological malignancy. Chimeric antigen receptor (CAR)-expressing T cells have been demonstrated successful in the clinic to treat B-lymphoid malignancies. However, the potential utility of antigen-specific CAR-engineered natural killer (NK) cells to treat MM has not been explored. In this study, we determined whether CS1, a surface protein that is highly expressed on MM cells, can be targeted by CAR NK cells to treat MM. We successfully generated a viral construct of a CS1-specific CAR and expressed it in human NK cells. In vitro, CS1-CAR NK cells displayed enhanced MM cytolysis and IFN-γ production, and showed a specific CS1-dependent recognition of MM cells. Ex vivo, CS1-CAR NK cells also showed similarly enhanced activities when responding to primary MM tumor cells. More importantly, in an aggressive orthotopic MM xenograft mouse model, adoptive transfer of NK-92 cells expressing CS1-CAR efficiently suppressed the growth of human IM9 MM cells and also significantly prolonged mouse survival. Thus, CS1 represents a viable target for CAR-expressing immune cells, and autologous or allogeneic transplantation of CS1-specific CAR NK cells may be a promising strategy to treat MM.

Potential therapeutic biomarkers in plasma cell myeloma: a flow cytometry study

OBJECTIVE

To investigate the expression profile of potential therapeutic biomarkers in plasma cell myeloma (PCM) by multicolor flow cytometry analysis.

METHODS

Bone marrow (BM) specimens were collected consecutively and analyzed using a routine PCM panel (CD38/CD138/CD45/CD19/CD20/CD28/CD56/CD117, cyto-kappa/lambda). The specimens were further assessed for CD30, CD44, CD49d, CD70, CD105, and CD184 expression in cases containing a substantial number of neoplastic plasma cells.

RESULTS

Totally, 101 patient BM samples were assessed, including 58 men and 43 women, with a median age of 64 years (34-89). Twenty-nine patients had newly diagnosed/untreated PCM, 40 had persistent/residual disease undergoing various therapies and 32 had relapsed disease. CD49d was expressed brightly and uniformly in all 45 patients tested. Expression of CD44 and CD184 was more variable with a median percentage of 77% (1-100) and 65% (5-100) respectively. Using an arbitrary 20% cutoff, CD44 was positive in 74 (73%) and CD184 in 92 (91%) cases with a mean fluorescence intensity ratio of 42.8 and 21.4. A higher CD44 expression was observed in patients with recurrent/persistent disease (P = 0.028). Additionally, both CD44 (P = 0.002) and CD184 (P = 0.026) showed higher expressions in CD117-positive cases, but there was no correlation with cytogenetic groups. The CD30, CD70, and CD105 were expressed very infrequently in PCM, with a median expression of 0.2%, 0.2%, and 0.4% respectively.

CONCLUSIONS

CD49d, CD44, and CD184, are highly expressed in PCM. CD49d expression is bright and uniform, whereas CD44 and CD184 are more heterogeneous. In contrast, surface CD30, CD70, and CD105 are infrequent. These data provide useful preclinical information for the design of potential novel targeted therapies in PCM patients.

Multiple myeloma-initiating cells

Multiple myeloma (MM) is characterized by the clonal expansion of malignant plasma cells. As in other cancers, MM plasma cells are thought to be derived from MM-initiating cells, although these remain unidentified. MM patients harbor phenotypic CD19(+) B cells expressing the immunoglobulin gene sequence and the idiotype unique to the individual myeloma clone. Some previous studies have reported that CD19(+) clonotypic B cells can serve as MM-initiating cells. However, we and another group have recently showed that CD19(+) B cells from many MM patients do not reconstitute MM disease upon transplantation into NOD/SCID IL2Rγc(-/-) mice. In the SCID-rab and SCID-hu models, which enable engraftment of human MM in vivo, CD19(-)CD38(++) plasma cells engrafted and rapidly propagated MM, while engraftment of CD19(+) B cells was not detected. Both CD138(-) and CD138(+) plasma cells have the potential to propagate MM clones in vivo in the absence of CD19(+) B cells. Distinct from acute myeloid leukemia-initiating cells, which are derived from undifferentiated stem or progenitor cells, MM-initiating cells are derived from plasma cells, which are terminally differentiated cells. An improved understanding of how the bone marrow microenvironment supports MM-initiating plasma cells, which can initiate MM disease in the SCID-hu (or rab) model, is thus now essential.

DNA repair dysregulation from cancer driver to therapeutic target

Dysregulation of DNA damage repair and signalling to cell cycle checkpoints, known as the DNA damage response (DDR), is associated with a predisposition to cancer and affects responses to DNA-damaging anticancer therapy. Dysfunction of one DNA repair pathway may be compensated for by the function of another compensatory DDR pathway, which may be increased and contribute to resistance to DNA-damaging chemotherapy and radiotherapy. Therefore, DDR pathways make an ideal target for therapeutic intervention; first, to prevent or reverse therapy resistance; and second, using a synthetic lethal approach to specifically kill cancer cells that are dependent on a compensatory DNA repair pathway for survival in the context of cancer-associated oxidative and replicative stress. These hypotheses are currently being tested in the laboratory and are being translated into clinical studies.