Ex vivo-expanded natural killer cells demonstrate robust proliferation in vivo in high-risk relapsed multiple myeloma patients.

Highly activated/expanded natural killer (NK) cells can be generated by stimulation with the human leukocyte antigen-deficient cell line K562, genetically modified to express 41BB-ligand and membrane-bound interleukin (IL)15. We tested the safety, persistence, and activity of expanded NK cells generated from myeloma patients (auto-NK) or haploidentical family donors (allo-NK) in heavily pretreated patients with high-risk relapsing myeloma. The preparative regimen comprised bortezomib only or bortezomib and immunosuppression with cyclophosphamide, dexamethasone, and fludarabine. NK cells were shipped overnight either cryopreserved or fresh. In 8 patients, up to 1×108 NK cells/kg were infused on day 0 and followed by daily administrations of IL2. Significant in vivo expansion was observed only in the 5 patients receiving fresh products, peaking at or near day 7, with the highest NK-cell counts in 2 subjects who received cells produced in a high concentration of IL2 (500 U/mL). Seven days after infusion, donor NK cells comprised >90% of circulating leukocytes in fresh allo-NK cell recipients, and cytolytic activity against allogeneic myeloma targets was retained in vitro. Among the 7 evaluable patients, there were no serious adverse events that could be related to NK-cell infusion. One patient had a partial response and in another the tempo of disease progression decreased; neither patient required further therapy for 6 months. In the 5 remaining patients, disease progression was not affected by NK-cell infusion. In conclusion, infusion of large numbers of expanded NK cells was feasible and safe; infusing fresh cells was critical to their expansion in vivo.

Clinical grade purification and expansion of natural killer cells.

Natural killer (NK) cells have been shown to have important functions in anti-tumor responses and therefore have been used as adoptive immunotherapy for cancer. Here, we review the current methods of ex vivo activation, enrichment, expansion, and shipment of clinical NK cell products.

Efficient lysis of epithelial ovarian cancer cells by MAGE-A3-induced cytotoxic T lymphocytes using rAAV-6 capsid mutant vector.

MAGE-A3 is highly expressed in epithelial ovarian cancer (EOC), making it a promising candidate for immunotherapy. We investigated whether dendritic cells (DCs) transduced with a rAAV-6 capsid mutant vector Y445F could elicit effective MAGE-A3-specific anti-tumor cytotoxic T lymphocyte (CTL) responses in vitro. MAGE-A3 was cloned and rAAV-6-MAGE-A3 purified, followed by proviral genome detection using real-time PCR. Immunofluorescence detection of rAAV-6-Y445F-MAGE-A3-transduced DCs demonstrated 60% transduction efficiency. Fluorescent in situ hybridization analysis confirmed chromosomal integration of rAAV vectors. Flow cytometric analysis of transduced DCs showed unaltered expression of critical monocyte-derived surface molecules with retention of allo-stimulatory activity. Co-culture of autologous T lymphocytes with MAGE-A3-expressing DCs produced CTLs that secreted IFN-γ, and efficiently killed MAGE-A3+ EOC cells. This form of rAAV-based DC immunotherapy, either alone or more likely in combination with other immune-enhancing protocols, may prove useful in the clinical setting for management of EOC.

Profile of elotuzumab and its potential in the treatment of multiple myeloma.

Although the introduction of novel drugs has improved outcome significantly in multiple myeloma (MM), many patients still eventually relapse. Monoclonal antibodies (mAbs) targeting MM-related antigens can complement currently available therapies. CS1 (also known as CD2 subunit 1, SLAMF7, CD319, and CRACC), a cell surface glycoprotein receptor that is a member of the signaling lymphocytic activation molecule (SLAM) family, is highly and nearly uniformly expressed in myeloma cells at the gene and protein level, but not expressed in other tissues, including hematopoietic stem cells, making CS1 a compelling target for the design of immunotherapies directed at MM. Elotuzumab (formerly HuLuc63), which is a humanized IgG1 mAb recognizing the extracellular region of human CS1, has been shown to be effective in preclinical and early stage clinical investigations, and its efficacy and safety will be further validated in ongoing Phase III trials. Integration of elotuzumab into multidrug therapeutic paradigms seems logical, as elotuzumab is more effective when combined with other agents, such as immunomodulatory drugs or proteasome inhibitors. The functional role of CS1 in MM pathogenesis and the consequences of elotuzumab on normal immune cells should be further investigated. Identification of potential biomarkers and exploration of resistance mechanisms are important issues for elotuzumab-based therapies, as is determining the best clinical placement of elotuzumab, not only in the relapsed/refractory setting but also in upfront therapy for high-risk frank MM, smoldering MM at high-risk of progression, and in maintenance regimens. This review will cover the biological characteristics of CS1 in normal immune cells and MM cells, the efficacy profile and mechanisms of action of elotuzumab from preclinical and clinical investigations, and its potential impact on the treatment of MM.

Interleukin-6 receptor polymorphism is prevalent in HIV-negative Castleman Disease and is associated with increased soluble interleukin-6 receptor levels.

Multicentric Castleman Disease is largely driven by increased signaling in the pathway for the plasma cell growth factor interleukin-6. We hypothesized that interleukin-6/interleukin-6 receptor/gp130 polymorphisms contribute to increased interleukin-6 and/or other components of the interleukin-6 signaling pathway in HIV-negative Castleman Disease patients. The study group was composed of 58 patients and 50 healthy donors of a similar racial/ethnic profile. Of seven polymorphisms chosen for analysis, we observed an increased frequency between patients and controls of the minor allele of interleukin-6 receptor polymorphism rs4537545, which is in linkage disequilibrium with interleukin-6 receptor polymorphism rs2228145. Further, individuals possessing at least one copy of the minor allele of either polymorphism expressed higher levels of soluble interleukin-6 receptor. These elevated interleukin-6 receptor levels may contribute to increased interleukin-6 activity through the trans-signaling pathway. These data suggest that interleukin-6 receptor polymorphism may be a contributing factor in Castleman Disease, and further research is warranted.

Large-scale ex vivo expansion and characterization of natural killer cells for clinical applications.

BACKGROUND AIMS: Interest in natural killer (NK) cell-based immunotherapy has resurged since new protocols for the purification and expansion of large numbers of clinical-grade cells have become available. METHODS: We have successfully adapted a previously described NK expansion method that uses K562 cells expressing interleukin (IL)-15 and 4-1 BB Ligand (BBL) (K562-mb15-41BBL) to grow NK cells in novel gas-permeable static cell culture flasks (G-Rex). RESULTS: Using this system we produced up to 19 × 10(9) functional NK cells from unseparated apheresis products, starting with 15 × 10(7) CD3(-) CD56 (+) NK cells, within 8-10 days of culture. The G-Rex yielded a higher fold expansion of NK cells than conventional gas-permeable bags and required no cell manipulation or feeding during the culture period. We also showed that K562-mb15-41BBL cells up-regulated surface HLA class I antigen expression upon stimulation with the supernatants from NK cultures and stimulated alloreactive CD8 (+) T cells within the NK cultures. However, these CD3 (+) T cells could be removed successfully using the CliniMACS system. We describe our optimized NK cell cryopreservation method and show that the NK cells are viable and functional even after 12 months of cryopreservation. CONCLUSIONS: We have successfully developed a static culture protocol for large-scale expansion of NK cells in the gas permeable G-Rex system under good manufacturing practice (GMP) conditions. This strategy is currently being used to produce NK cells for cancer immunotherapy.

Highly activated and expanded natural killer cells for multiple myeloma immunotherapy.

BACKGROUND: Patients with gene expression profiling-defined high-risk myeloma in relapse have poor outcomes with current therapies. We tested whether natural killer cells expanded by co-culture with K562 cells transfected with 41BBL and membrane-bound interleukin-15 could kill myeloma cells with a high-risk gene expression profile in vitro and in a unique model which recapitulates human myeloma. DESIGN AND METHODS: OPM2 and high-risk primary myeloma tumors were grown in human fetal bone implanted into non-obese diabetic severe combined immunodeficiency mice with a deficient interleukin-2 receptor gamma chain. These mice are devoid of endogenous natural killer and T-cell activity and were used to determine whether adoptively transferred expanded natural killer cells could inhibit myeloma growth and myeloma-associated bone destruction. RESULTS: Natural killer cells from healthy donors and myeloma patients expanded a median of 804- and 351-fold, respectively, without significant T-cell expansion. Expanded natural killer cells killed both allogeneic and autologous primary myeloma cells avidly via a perforin-mediated mechanism in which the activating receptor NKG2D, natural cytotoxicity receptors, and DNAX-accessory molecule-1 played a central role. Adoptive transfer of expanded natural killer cells inhibited the growth of established OPM2 and high-risk primary myeloma tumors grown in the murine model. The transferred, expanded natural killer cells proliferated in vivo in an interleukin-2 dose-dependent fashion, persisted up to 4 weeks, were readily detectable in the human bone, inhibited myeloma growth and protected bone from myeloma-induced osteolysis. CONCLUSIONS: These studies provide the rationale for testing expanded natural killer cells in humans.

Epigenetic modulation of MAGE-A3 antigen expression in multiple myeloma following treatment with the demethylation agent 5-azacitidine and the histone deacetlyase inhibitor MGCD0103.

BACKGROUND AIMS: Immunotherapy targeting MAGE-A3 in multiple myeloma (MM) could eradicate highly aggressive and proliferative clonal cell populations responsible for relapse. However, expression of many cancer-testis antigens, including MAGE-A3, can be heterogeneous, leading to the potential for tumor escape despite MAGE-A3-induced immunity. We hypothesized that a combination of the hypomethylating agent 5-azacitidine (5AC) and the histone deacetylase inhibitor (HDACi) MGCD0103 (MGC) could induce MAGE-A3 expression in MAGE-A3-negative MM, resulting in recognition and killing of MM cells by MAGE-A3-specific cytotoxic T lymphocytes (CTL). METHODS: Gene expression analyses of MAGE-A3 expression in primary MM patient samples at diagnosis and relapse were completed to identify populations that would benefit from MAGE-A3 immunotherapy. MM cell lines were treated with 5AC and MGC. Real-time polymerase chain reaction (PCR) and Western blotting were performed to assess MAGE-A3 RNA and protein levels, respectively. Chromium-release assays and interferon (IFN) secretion assays were employed to ascertain MAGE-A3 CTL specificity against treated targets. RESULTS: Gene expression analysis revealed that MAGE-A3 is expressed in MM patients at diagnosis (25%) and at relapse (49%). We observed de novo expression of MAGE-A3 RNA and protein in MAGE-A3-negative cell lines treated with 5AC. MGC treatment alone did not induce expression but sequential 5AC/MGC treatment led to enhanced expression and augmented recognition by MAGE-A3-specific CTL, as assessed by (51)Cr-release assays (P = 0.047) and enzyme-linked immunosorbent assay (ELISA) for IFN-γ secretion (P = 0.004). CONCLUSIONS: MAGE-A3 is an attractive target for immunotherapy of MM and epigenetic modulation by 5AC, and MGC can induce MAGE-A3 expression and facilitate killing by MAGE-A3-specific CTL.

Castleman disease in the 21st century: an update on diagnosis, assessment, and therapy.

Castleman disease (CD) is a nonclonal lymphoproliferative disorder that can affect single lymph node stations or, alternatively, can be generalized. Interleukin 6 (IL6) plays a pivotal role in the pathophysiology of CD. Human herpesvirus 8 (HHV8), which encodes a viral homolog of IL6, is the driving force in HIV-positive patients. The role of HHV8 in HIV-negative CD is controversial. Historically, the prognosis of patients with generalized or multicentric CD has been thought to be poor. However, CD responds extremely well to monoclonal antibodies directed at the IL6 receptor or IL6 itself, and in general, the long-term outcome of HIV-negative CD is excellent. Important strides forward have also been made in the management of HIV-positive CD.

Optimizing dendritic cell-based immunotherapy in multiple myeloma: intranodal injections of idiotype-pulsed CD40 ligand-matured vaccines led to induction of type-1 and cytotoxic T-cell immune responses in patients.

Vaccination with idiotype (Id) protein-pulsed dendritic cells (DCs) has been explored in multiple myeloma and the results have been disappointing. To improve the efficacy of DC vaccination in myeloma, we investigated the use of Id- and keyhole limpet haemocyanin (KLH)-pulsed, CD40 ligand-matured DCs administered intranodally. Nine patients with smouldering or stable myeloma without treatment were enrolled and DC vaccines were administered at weekly intervals for a total of four doses. Following vaccination, all patients mounted Id-specific gamma-interferon T-cell response. Interleukin-4 response was elicited in two, and skin delayed-type hypersensitivity reaction occurred in seven patients. More importantly, Id-specific cytotoxic T-cell responses were also detected in five patients. Most if not all patients mounted a positive T-cell response to KLH following vaccination. At 1-year follow-up, six of the nine patients had stable disease, while three patients had slowly progressive disease even during the vaccination period. At 5-year follow-up, four of the six patients continued with stable disease. No major side effects were noted. In summary, intranodal administration of Id-pulsed CD40 ligand-matured DCs was able to induce Id-specific T and B-cell responses in patients. Current efforts are geared towards breaking tumour-mediated immune suppression and improving clinical efficacy of this immunotherapy.

Combinatorial efficacy of anti-CS1 monoclonal antibody elotuzumab (HuLuc63) and bortezomib against multiple myeloma.

Monoclonal antibody (mAb) therapy for multiple myeloma, a malignancy of plasma cells, has not been clinically efficacious in part due to a lack of appropriate targets. We recently reported that the cell surface glycoprotein CS1 (CD2 subset 1, CRACC, SLAMF7, CD319) was highly and universally expressed on myeloma cells while having restricted expression in normal tissues. Elotuzumab (formerly known as HuLuc63), a humanized mAb targeting CS1, is currently in a phase I clinical trial in relapsed/refractory myeloma. In this report we investigated whether the activity of elotuzumab could be enhanced by bortezomib, a reversible proteasome inhibitor with significant activity in myeloma. We first showed that elotuzumab could induce patient-derived myeloma cell killing within the bone marrow microenvironment using a SCID-hu mouse model. We next showed that CS1 gene and cell surface protein expression persisted on myeloma patient-derived plasma cells collected after bortezomib administration. In vitro bortezomib pretreatment of myeloma targets significantly enhanced elotuzumab-mediated antibody-dependent cell-mediated cytotoxicity, both for OPM2 myeloma cells using natural killer or peripheral blood mononuclear cells from healthy donors and for primary myeloma cells using autologous natural killer effector cells. In an OPM2 myeloma xenograft model, elotuzumab in combination with bortezomib exhibited significantly enhanced in vivo antitumor activity. These findings provide the rationale for a clinical trial combining elotuzumab and bortezomib, which will test the hypothesis that combining both drugs would result in enhanced immune lysis of myeloma by elotuzumab and direct targeting of myeloma by bortezomib.

Infusion of haplo-identical killer immunoglobulin-like receptor ligand mismatched NK cells for relapsed myeloma in the setting of autologous stem cell transplantation.

Killer immunoglobulin-like receptor (KIR)-ligand mismatched natural killer (NK) cells play a key role in achieving durable remission after haplo-identical transplantation for acute myeloid leukaemia. We investigated the feasibility of transfusing haplo-identical, T-cell depleted, KIR-ligand mismatched NK cells, after conditioning therapy with melphalan and fludarabine, to patients with advanced multiple myeloma (MM) followed by delayed rescue with autologous stem cells. No graft-versus-host disease or failure of autologous stem cells to engraft was observed. There was significant variation in the number of allo-reactive NK cells transfused. However, all NK products containing allo-reactive NK cells killed the NK cell target K562, the MM cell line U266, and recipient MM cells when available. Post NK cell infusion there was a rise in endogenous interleukin-15 accompanied by increasing donor chimaerism. Donor chimaerism was eventually lost, which correlated with the emergence of potent host anti-donor responses indicating that the immunosuppressive properties of the conditioning regimen require further optimization. Further, blocking of inhibitory KIR-ligands with anti-human leucocyte antigen antibody substantially enhanced killing of MM cells thus highlighting the potential for modulating NK/MM cell interaction. Encouragingly, 50% of patients achieved (near) complete remission. These data set the stage for future studies of KIR-ligand mismatched NK cell therapy in the autologous setting.

CS1, a potential new therapeutic antibody target for the treatment of multiple myeloma.

PURPOSE: We generated a humanized antibody, HuLuc63, which specifically targets CS1 (CCND3 subset 1, CRACC, and SLAMF7), a cell surface glycoprotein not previously associated with multiple myeloma. To explore the therapeutic potential of HuLuc63 in multiple myeloma, we examined in detail the expression profile of CS1, the binding properties of HuLuc63 to normal and malignant cells, and the antimyeloma activity of HuLuc63 in preclinical models. EXPERIMENTAL DESIGN: CS1 was analyzed by gene expression profiling and immunohistochemistry of multiple myeloma samples and numerous normal tissues. HuLuc63-mediated antimyeloma activity was tested in vitro in antibody-dependent cellular cytotoxicity (ADCC) assays and in vivo using the human OPM2 xenograft model in mice. RESULTS: CS1 mRNA was expressed in >90% of 532 multiple myeloma cases, regardless of cytogenetic abnormalities. Anti-CS1 antibody staining of tissues showed strong staining of myeloma cells in all plasmacytomas and bone marrow biopsies. Flow cytometric analysis of patient samples using HuLuc63 showed specific staining of CD138+ myeloma cells, natural killer (NK), NK-like T cells, and CD8+ T cells, with no binding detected on hematopoietic CD34+ stem cells. HuLuc63 exhibited significant in vitro ADCC using primary myeloma cells as targets and both allogeneic and autologous NK cells as effectors. HuLuc63 exerted significant in vivo antitumor activity, which depended on efficient Fc-CD16 interaction as well as the presence of NK cells in the mice. CONCLUSIONS: These results suggest that HuLuc63 eliminates myeloma cells, at least in part, via NK-mediated ADCC and shows the therapeutic potential of targeting CS1 with HuLuc63 for the treatment of multiple myeloma.

Bortezomib down-regulates the cell-surface expression of HLA class I and enhances natural killer cell-mediated lysis of myeloma.

Human leukocyte antigen class I molecules expressed by tumor cells play a central role in the regulation of natural killer (NK) cell-mediated immune responses. The proteasome inhibitor bortezomib has demonstrated significant activity in multiple myeloma (MM). We hypothesized that treatment of MM with bortezomib results in the reduction of cell-surface expression of class I and thereby sensitizes MM to NK cell-mediated lysis. Here we report that bortezomib down-regulates class I in a time- and dose-dependent fashion on all MM cell lines and patient MM cells tested. Downregulation of class I can also be induced in vivo after a single dose of 1.0 mg/m(2) bortezomib. Bortezomib significantly enhances the sensitivity of patient myeloma to allogeneic and autologous NK cell-mediated lysis. Further, the level of decrease in class I expression correlates with increased susceptibility to lysis by NK cells. Clinically relevant bortezomib concentrations do not affect NK-cell function. Our findings have clear therapeutic implications for MM and other NK cell-sensitive malignancies in the context of both allogeneic and autologous adoptively transferred NK cells.

Immunization with a recombinant MAGE-A3 protein after high-dose therapy for myeloma.

MAGE-A3 is frequently expressed in high-risk multiple myeloma (MM). We immunized a healthy donor with MAGE-A3 protein formulated in AS02B to transfer immunity to her identical twin, diagnosed with MAGE-A3-positive MM. After a melphalan 200 mg/m syngeneic peripheral blood stem cell transplant, primed donor cells collected after immunizations were transferred and followed by repeated patient immunizations. MAGE-A3 immunizations were well tolerated. Strong MAGE-A3-specific antibody, cytotoxic T-lymphocyte (CTL), and T-helper responses were induced in both twins. A humoral response was transferred to the patient with the donor peripheral blood stem cells and increased by booster immunization. The CTL response targeted a previously undescribed HLA-A*6801 binding MAGE-A3115-123 peptide. MAGE-A3115-123 CTLs were detected in the patient more than 1 year after the last immunization. Multiple T-helper cellular responses were detected with the dominant response to an HLA-DR11 restricted MAGE-A3 epitope. The patient remains in remission 2.5 years after the second transplant. This report shows for the first time that immunization of a healthy donor with a defined cancer-testis protein induces immune responses that can be transferred and expanded posttransplant in the recipient. MAGE-A3 immunization may be a useful adjunct to high dose melphalan-based peripheral blood stem cell transplant, providing a new therapeutic option for high-risk MM.

NY-ESO-1 immunotherapy for multiple myeloma.

Most patients with poor-prognosis myeloma (abnormal metaphase cytogenetics) achieve excellent responses with tandem transplants, but the remissions are not durable. Novel interventions such as immunotherapy may eradicate the residual chemotherapy-resistant disease. Immunotherapy targeting weak antigens such as myeloma idiotype or tumor lysate has failed to produce clinically meaningful responses. We previously reported that the NY-ESO-1 antigen is expressed in >60% of poor-prognosis myeloma at diagnosis. Since NY-ESO-1 is highly immunogenic and is not expressed in most normal tissues, it is an ideal target for anti-myeloma immunotherapy. NY-ESO-1 based therapies are already being tested in clinical trials for a multitude of tumors. This review discusses the potential of NY-ESO-1 immunotherapy to improve outcome for myeloma.

Protein transduction of dendritic cells for NY-ESO-1-based immunotherapy of myeloma.

Myeloma vaccines, based on dendritic cells pulsed with idiotype or tumor lysate, have been met with limited success, probably in part due to insufficient cross-priming of myeloma antigens. A powerful method to introduce myeloma-associated antigens into the cytosol of dendritic cells is protein transduction, a process by which proteins fused with a protein transduction domain (PTD) freely traverse membrane barriers. NY-ESO-1, an immunogenic antigen by itself highly expressed in 60% of high-risk myeloma patients, was purified to near homogeneity both alone and as a recombinant fusion protein with a PTD, derived from HIV-Tat. Efficient entry of PTD-NY-ESO-1 into dendritic cells, confirmed by microscopy, Western blotting, and intracellular flow cytometry, was achieved without affecting dendritic cell phenotype. Experiments with amiloride, which inhibits endocytosis, and N-acetyl-l-leucinyl-l-norleucinal, a proteasome inhibitor, confirmed that PTD-NY-ESO-1 entered dendritic cells by protein transduction and was degraded by the proteasome. Tetramer analysis indicated superior generation of HLA-A2.1, CD8+ T lymphocytes specific for NY-ESO-1(157-165) with PTD-NY-ESO-1 compared with NY-ESO-1 control protein (44% versus 2%, respectively). NY-ESO-1-specific T lymphocytes generated with PTD-NY-ESO-1 secreted IFN-gamma indicative of a Tc1-type cytokine response. Thus, PTD-NY-ESO-1 accesses the cytoplasm by protein transduction, is processed by the proteasome, and NY-ESO-1 peptides presented by HLA class I elicit NY-ESO-1-specific T lymphocytes.

NY-ESO-1 is highly expressed in poor-prognosis multiple myeloma and induces spontaneous humoral and cellular immune responses.

The presence of a metaphase cytogenetic abnormality (CA) is the key negative predictor of outcome in patients with multiple myeloma (MM). Gene expression profiling (GEP) of such patients showed increased expression of NY-ESO-1 compared to patients with normal cytogenetics (60% versus 31%; P = .004). NY-ESO-1 was also highly expressed in relapsing MM especially patients with CA (100% versus 60.7%; P < .001). GEP findings were confirmed at the protein level by immunostaining of marrow biopsies for NY-ESO-1. We detected spontaneous NY-ESO-1-specific antibodies by enzyme-linked immunosorbent assay in 33% of patients with NY-ESO-1+ MM, especially in CA patients (9 of 13; 70%), but in none of the NY-ESO-1- patients with MM (n = 27) or healthy donors (n = 21). Spontaneous NY-ESO-1(157-165)-specific T cells (0.2%-0.6% of CD8+ T cells) were found in the peripheral blood of NY-ESO-1+ MM with HLA-A*0201/NY-ESO-1(157-165) tetramers. These NY-ESO-1-specific T cells, when expanded, killed primary MM cells (50% lysis, effector-target [E/T] ratio, 10:1). Our data demonstrate that NY-ESO-1 is frequently expressed in MM with CA and is capable of eliciting spontaneous humoral and T-cell immunity. The pool of NY-ESO-1-specific cytotoxic T cells expands easily on NY-ESO-1 peptide stimulation and is functionally active. NY-ESO-1 should therefore be an ideal tumor target antigen for immunotherapy of patients with poor-prognosis MM.