Lenalidomide enhances antigen-specific activity and decreases CD45RA expression of T cells from patients with multiple myeloma

Lenalidomide improves NKG2D-based CAR-T cell activity against colorectal cancer cells invitro

Introduction

Although CAR-based immunotherapy is viewed as a promising treatment for tumors, particularly hematological malignancies, solid tumors can pose challenges. It has been suggested that the immunomodulatory medication Lenalidomide (LEN) may increase the effectiveness of CAR T cells in the treatment of solid tumors. The purpose of our study was to investigate the effect of NKG2D-based CAR T cell therapy on colorectal cancer cell lines, and then we assessed combinatorial therapy using NKG2D CAR T cells and lenalidomide in vitro.

Methods and results

To prepare NKG2D CAR T cells, a second-generation NKG2D-CAR construct was designed and transfected into the T cells using a lentiviral system. The NKG2D CAR T cells showed significantly higher cytotoxic activity against colorectal cancer cell lines, HCT116 and SW480, compared to untransduced T cells. In addition, our data demonstrated that the cytotoxicity and cytokine secretion of NKG2D CAR T cells significantly increased in the presence of higher doses of lenalidomide.

Conclusions

The study findings suggest that combinational therapy, utilizing NKG2D-based CAR T cells and lenalidomide, has a high potential for effectively eliminating tumor cells in vitro.

Definition and Characterization of SOX11-Derived T Cell Epitopes towards Immunotherapy of Glioma

The transcription factor SOX11 is a tumor-associated antigen with low expression in normal cells, but overexpression in glioblastoma (GBM). So far, conventional surgery, chemotherapy, and radiotherapy have not substantially improved the dismal prognosis of relapsed/refractory GBM patients. Immunotherapy is considered a promising strategy against GBM, but there is a fervent need for better immunotargets in GBM. To this end, we performed an in silico prediction study on SOX11, which primarily yielded ten promising HLA-A*0201-restricted peptides derived from SOX11. We defined a novel peptide FMACSPVAL, which had the highest score according to in silico prediction (6.02 nM by NetMHC-4.0) and showed an exquisite binding affinity to the HLA-A*0201 molecule in the peptide-binding assays. In the IFN-γ ELISPOT assays, FMACSPVAL demonstrated a high efficiency for generating SOX11-specific CD8⁺ T cells. Nine out of thirty-two healthy donors showed a positive response to SOX11, as assessed by the ELISPOT assays. Therefore, this novel antigen peptide epitope seems to be promising as a target for T cell-based immunotherapy in GBM. The adoptive transfer of in vitro elicited SOX11-specific CD8⁺ T cells constitutes a potential approach for the treatment of GBM patients.

Cytokines as Potential Therapeutic Targets and their Role in the Diagnosis and Prediction of Cancers

The death rate from cancer is declining as a result of earlier identification and more advanced treatments. Nevertheless, a number of unfavourable adverse effects, including prolonged, long-lasting inflammation and reduced immune function, usually coexist with anti-cancer therapies and lead to a general decline in quality of life. Improvements in standardized comprehensive therapy and early identification of a variety of aggressive tumors remain the main objectives of cancer research. Tumor markers in those with cancer are tumor- associated proteins that are clinically significant. Even while several tumor markers are routinely used, they don't always provide reliable diagnostic information. Serum cytokines are promising markers of tumor stage, prognosis, and responsiveness to therapy. In fact, several cytokines are currently proposed as potential biomarkers in a variety of cancers. It has actually been proposed that the study of circulatory cytokines together with biomarkers that are particular to cancer can enhance and accelerate cancer diagnosis and prediction, particularly via blood samples that require minimal to the absence of invasion. The purpose of this review was to critically examine relevant primary research literature in order to elucidate the role and importance of a few identified serum cytokines as prospective therapeutic targets in oncological diseases.

Value of Cytokine Expression in Early Diagnosis and Prognosis of Tumor Metastasis

Objective

To investigate the association of the plasma level of cytokines and blood routine indexes with clinical characteristics in patients with cancer.

Methods

We analyzed plasma samples derived from 134 cancer patients. Interleukins (IL) 1β, 2, 4, 5, 6, 8, 10, 12p70, 17, IFN-γ, IFN-α, and TNF-α, and blood routine indexes were measured. The associations of the levels of cytokine and blood routine indexes with demographic and clinical characteristics of cancer patients were analyzed. Partial least-squares discriminant analysis was employed to identify cancer metastasis using these plasma cytokine metrics as input. We compared the predictive effectiveness of numeric machine learning algorithms using these indexes and showed a promising model implemented with random forest.

Results

Plasma levels of IL-6 and IL-8 in cancer patients with metastases were higher than those without metastases (P < 0.05). Cancer patients without metastases had significantly higher levels of plasma IL-12p70 and percentage of lymphocytes as compared with those with metastases (P < 0.05). Our random forest model showed the highest prediction performance (upper quantile AUC, 0.885) among the six machine learning algorithms we evaluated.

Conclusion

Our findings suggest that plasma levels of IL-6, IL-8, and IL-12p70 and the percentage of lymphocytes could predict the recurrence, metastasis, and progression of cancer. Our findings will provide guidance for tumor monitoring and treatment.

Molecular Mechanisms of Cereblon-Interacting Small Molecules in Multiple Myeloma Therapy

Thalidomide analogues (or immunomodulatory imide drugs, IMiDs) are cornerstones in the treatment of multiple myeloma (MM). These drugs bind Cereblon (CRBN), a receptor for the Cullin-ring 4 ubiquitin-ligase (CRL4) complex, to modify its substrate specificity. IMiDs mediate CRBN-dependent engagement and proteasomal degradation of ‘neosubstrates’, Ikaros (IKZF1) and Aiolos (IKZF3), conveying concurrent antimyeloma activity and T-cell costimulation. There is now a greater understanding of physiological CRBN functions, including endogenous substrates and chaperone activity. CRISPR Cas9-based genome-wide screening has further elucidated the complex cellular machinery implicated in IMiD sensitivity, including IKZF1/3-independent mechanisms. New-generation IMiD derivatives with more potent anti-cancer properties—the CELMoDs (Cereblon E3 ligase modulators)—are now being evaluated. Rational drug design also allows ‘hijacking’ of CRL4^CRBN utilising proteolysis targeting chimeras (PROTACs) to convey entirely distinct substrate repertoires. As all these chemotypes—thalidomide, IMiDs, CELMoDs and PROTACs—engage CRBN and modify its functions, we describe them here in aggregate as ‘CRBN-interacting small molecules’ (CISMs). In this review, we provide a contemporary summary of the biological consequences of CRBN modulation by CISMs. Detailed molecular insight into CRBN–CISM interactions now provides an opportunity to more effectively target previously elusive cancer dependencies, representing a new and powerful tool for the implementation of precision medicine.

An Allogeneic Multiple Myeloma GM-CSF-Secreting Vaccine with Lenalidomide Induces Long-term Immunity and Durable Clinical Responses in Patients in Near Complete Remission

PURPOSE

This proof-of-principle clinical trial evaluated whether an allogeneic multiple myeloma GM-CSF-secreting vaccine (MM-GVAX) in combination with lenalidomide could deepen the clinical response in patients with multiple myeloma in sustained near complete remission (nCR).

PATIENTS AND METHODS

Fifteen patients on lenalidomide were treated with MM-GVAX and pneumococcal conjugate vaccine (PCV; Prevnar) at 1, 2, 3, and 6 months.

RESULTS

Eight patients (53.3%) achieved a true CR. With a median follow-up of 5 years, the median progression-free survival had not been reached, and the median overall survival was 7.8 years from enrollment. MM-GVAX induced clonal T-cell expansion and measurable cytokine responses that persisted up to 7 years in all patients. At baseline, a higher minimal residual disease was predictive of early relapse. After vaccination, a lack of both CD27^-DNAM1^-CD8⁺ T cells and antigen-presenting cells was associated with disease progression.

CONCLUSIONS

MM-GVAX, along with lenalidomide, effectively primed durable immunity and resulted in long-term disease control, as suggested by the reappearance of a detectable, fluctuating M-spike without meeting the criteria for clinical relapse. For patients in a nCR, MM-GVAX administration was safe and resulted in prolonged clinical responses.

Cellular immunotherapy in multiple myeloma

In multiple myeloma (MM), the impaired function of several types of immune cells favors the tumor's escape from immune surveillance and, therefore, its growth and survival. Tremendous improvements have been made in the treatment of MM over the past decade but cellular immunotherapy using dendritic cells, natural killer cells, and genetically engineered T-cells represent a new therapeutic era. The application of these treatments is growing rapidly, based on their capacity to eradicate MM. In this review, we summarize recent progress in cellular immunotherapy for MM and its future prospects.

IL-10 inducible CD8+ regulatory T-cells are enriched in patients with multiple myeloma and impact the generation of antigen-specific T-cells

Tumor-mediated immunosuppression via regulatory T-cells is a key player among the various immune-escape mechanisms in multiple myeloma. We analyzed the generation, distribution, function and immunophenotype of CD8+CD28- regulatory T-cells in patients with multiple myeloma. Functionality of CD8+CD28- T-cells was assessed by immunological assays using ex vivo generated antigen-specific T-cells from patients with plasma cell dyscrasias and healthy donors. Detailed analysis of distribution, immunophenotype and cytotoxic potential of CD8+CD28- T-cells was performed by flow cytometry and ELISA. We found that the amount of CD8+CD28- T-cells was directly correlated with the suppression of antigen-specific T-cell responses in patients with plasma cell dyscrasia. Analyzing the CD8+CD28- T-cells in detail, increased numbers of these cells were observed in the bone marrow (i.e., tumor microenvironment) of patients with plasma cell dyscrasia. Furthermore, we identified the expression of lymphocyte function-associated antigen 1 (LFA-1) as a marker of immunosuppression and defined the CD8+CD28-CD57+LFA-1high population as the relevant immunosuppressive compartment. These regulatory T-cells act as immunosuppressors via soluble factors and incubation with IL-10 augmented their immunosuppressive capacity. The immunosuppressive regulatory network of IL-10 and the CD8+CD28-CD57+LFA-1high regulatory T-cells show unique characteristics and contribute to the tumor immune escape mechanism in patients with multiple myeloma.

The prognostic and predictive value of IKZF1 and IKZF3 expression in T-cells in patients with multiple myeloma

Purpose: While recent studies described the role of IKZF1/3 proteins in multiple myeloma (MM) cells, few have highlighted the significance of IKZF1/3 expression in T-cells. In this study we examine the prognostic and predictive value of IKZF1/3 expression in T-cells in patients with MM stage III. Experimental design: We analysed the IKZF1/3 expression levels in T-cells from 45 MM stage I (MMI) and 50 newly diagnosed MM stage III (MMIII) patients, according to Durie-Salmon staging system, by flow cytometry to examine their prognostic and predictive value. We also combined in vivo observations with in vitro assays to determine the effect of IKZF1/3 expression on the T-cell immunophenotype and anti-tumour T-cell response in 162 MMIII patients. Results: We found that high IKZF3, but not IKZF1, expression in T-cells correlates with superior overall survival in MMIII patients treated with immunomodulatory drugs (thalidomide, lenalidomide and pomalidomide). Moreover, we show that higher IKZF3 expression in T-cells inhibits myeloma-specific T-cell response in vitro and that the immunophenotype of patients with high IKZF3 expression shows features that are contrary to the changes induced by immunomodulatory drugs. Although we observed higher IKZF3 expression levels in T-cells from patients with MMIII compared to MMI, IKZF3 expression was unaffected by the tumour microenvironment. Conclusion: In conclusion, IKZF3 expression in T-cells is a predictive value for clinical outcome in MMIII patients treated with immunomodulatory drugs due to its profound modulation of T-cell functionality.

A phase I clinical study of autologous dendritic cell therapy in patients with relapsed or refractory multiple myeloma

Cellular immunotherapy is emerging as a potential immunotherapeutic modality in multiple myeloma (MM). We have developed potent immunotherapeutic agent (VAX-DC/MM) generated by dendritic cells (DCs) loaded with autologous myeloma cells irradiated with ultraviolet B. In this study, we evaluated the safety and efficacy of VAX-DC/MM in patients with relapsed or refractory MM. This trial enrolled relapsed or refractory MM patients who had received both thalidomide- and bortezomib-based therapies. Patients received the intradermal VAX-DC/MM injection every week for 4 weeks. Patients were treated with 5 × 10⁶ or 10 × 10⁶ cells, with nine patients treated at a higher dose. The median time from diagnosis to VAX-DC/MM therapy was 56.6 months (range, 28.5–130.5). Patients had received a median of five prior treatments, and 75% had received autologous stem cell transplantation. VAX-DC therapy was well-tolerated, and the most frequent adverse events were local reactions at the injection site and infusion-related reactions. In seven of nine patients who received 10×10⁶ cells, an immunological response (77.8%) was observed by interferon-gamma ELISPOT assay or a mixed lymphocyte reaction assay for T-cell proliferation. The clinical benefit rate was 66.7% including one (11.1%) with minor response and five (55.6%) with stable disease; three (33.3%) patients showed disease progression. In conclusion, VAX-DC/MM therapy was well-tolerated, and had disease-stabilizing activity in heavily pretreated MM cases. Further studies are needed to increase the efficacy of VAX-DC/MM in patients with MM.

Pilot trial of K562/GM-CSF whole-cell vaccination in MDS patients

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematopoietic stem cell malignancies. Currently, approved drugs are given with non-curative intent as the only known cure is allogeneic bone marrow transplantation, which relies on the donor's immune system driving an allogeneic effect. Previous efforts to harness the endogenous immune system have been less successful. We present the results of a pilot study of K562/GM-CSF (GVAX) whole-cell vaccination in MDS patients. The primary objective of safety was met as there were no serious adverse events. One patient had a decrease in transfusion requirements and another demonstrated hematologic improvement suggesting a signal for clinical activity. In vitro correlative studies indicated biological effects on immune cells following vaccination. Although only a pilot study, results are encouraging that an immunotherapeutic approach with a whole-cell vaccine may be feasible in MDS patients.

Lenalidomide overcomes the immunosuppression of regulatory CD8+CD28- T-cells

Although lenalidomide and pomalidomide are well-established treatment options in patients with multiple myeloma, their immune-modulating effects are not fully understood. While CD8⁺CD28⁻ regulatory T-cells in patients with hematologic disorders display a known immune-escape mechanism, we show that lenalidomide can overcome the immunosuppressive impact of CD8⁺CD28⁻ T-cells.

We analyzed in vitro the antigen-specific T-cell responses of healthy donors and patients with multiple myeloma with or without the addition of autologous CD8⁺CD28⁻ T-cells in the absence and presence of lenalidomide. We found that lenalidomide enhances the antigen-specific secretion of IFN-γ and Granzyme B despite the addition of CD8⁺CD28⁻ T-cells. Furthermore, we showed that lenalidomide inhibits the IL-6 secretion of mononuclear cells, triggered by CD8⁺CD28⁻ T-cells. The addition of IL-6 counteracts the action of lenalidomide based stimulation of IFN-γ secretion and induction of T-cell maturation but not the secretion of Granzyme B. Surprisingly, pomalidomide failed to induce IL-6 suppression and displayed immunostimulating effects only after a prolonged incubation time. Analysis of the IL-6 modulating cereblon-binding protein KPNA2 showed the similar degradation capacity of lenalidomide and pomalidomide without explaining the divergent effects. In conclusion, we showed that IL-6 and lenalidomide, but not pomalidomide, are opponents in a myeloma-antigen specific T-cell model.

Immunotherapy for the treatment of multiple myeloma

Immunotherapy has recently emerged as a promising treatment for multiple myeloma (MM). There are now several monoclonal antibodies that target specific surface antigens on myeloma cells or the checkpoints of immune and myeloma cells. Elotuzumab (targeting SLAMF7), daratumumab (targeting CD38), and pembrolizumab (targeting PD-1) have shown clinical activity in clinical studies with relapsed/refractory MM. Dendritic cell vaccination is a safe strategy that has shown some efficacy in a subset of myeloma patients and may become a crucial part of MM treatment when combined with immunomodulatory drugs or immune check-point blockade. Genetically engineered T cells, such as chimeric antigen receptor T cells or T cell receptor-engineered T cells, have also shown encouraging results in recent clinical studies of patients with MM. In this paper, we discuss recent progress in immunotherapy for the treatment of MM.

Phase I-II study of lenalidomide and alemtuzumab in refractory chronic lymphocytic leukemia (CLL): effects on T cells and immune checkpoints

This phase I–II study explored safety, immunomodulatory and clinical effects of lenalidomide (weeks 1–16) and alemtuzumab (weeks 5–16) in 23 patients with refractory chronic lymphocytic leukemia. Most patients had Rai stage III/IV disease and were heavily pretreated (median 4 prior therapies), and 61% had del(17p)/del(11q). Eleven of 19 evaluable patients (58%) responded, with a median response duration of 12 months (1–29+); time to progression was short in non-responders. Lenalidomide had a narrow therapeutic dose range, 2.5 mg/day was not efficient, and maximum tolerated dose was 5 mg/day. Grade 3–4 neutropenia and thrombocytopenia occurred in 84 and 55%, 30% had febrile neutropenia, and CMV-reactivation requiring valganciclovir occurred in 30% of patients. The frequency of proliferating (Ki67⁺) CD8⁺ T cells was increased at week 4, with further increase in both the CD4⁺ and CD8⁺ subsets (p < 0.01 and <0.05), which was accompanied by significant upregulation of HLA-DR after addition of alemtuzumab. Antigen-experienced cells increased at week 4 as the frequency of effector memory cells increased in the CD8⁺ subset (p < 0.003), while effector cells decreased in both the CD8⁺ and CD4⁺ subsets (p < 0.0001 and p < 0.01). The Th1/Th2 balance was unchanged at week 4 but shifted toward a Th2 profile after combination therapy. At end of treatment, the frequency of Th17 and regulatory T cells was reduced (p < 0.01), naïve T cells decreased, and effector memory T cells increased (p < 0.05 and p < 0.01). Granzyme B⁺ T cells increased at 30-week follow-up (p < 0.05). PD-1 expression was unaffected. In conclusion, low-dose lenalidomide and alemtuzumab induced major perturbations of T cells, including increased proliferative activity and cytotoxic potential.

The immunotherapy era of myeloma: monoclonal antibodies, vaccines, and adoptive T-cell therapies

The treatment of multiple myeloma has evolved significantly over the last decades from primarily alkylator-based chemotherapeutic agents with minimal efficacy to the introduction of more effective agents including immune modulators and proteasome inhibitors, which have changed the landscape of therapy for this disease. We are now entering a new era that will increasingly integrate immunotherapy into standard treatment. This review discusses the current immune-based strategies currently approved, as well as various immune approaches being actively investigated including monoclonal antibodies, checkpoint inhibitors, vaccines, and adoptive T-cell therapies.

Myeloid-derived suppressor cells: The green light for myeloma immune escape

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous, immature myeloid cell population with the ability to suppress innate and adaptive immune responses that promote tumor growth. MDSCs are increased in patients with multiple myeloma (MM) and have bidirectional interaction with tumors within the MM microenvironment. MM-MDSCs promote MM tumor growth and induce immune suppression; conversely, MM cells induce MDSC development and survival. Although the role of MDSCs in infections, inflammatory diseases and solid tumors has been extensively characterized, their tumor-promoting and immune-suppressive role in MM and the MM microenvironment is only beginning to emerge. The presence and activation of MDSCs in MM patients has been well documented; however, the direct actions and functional consequences of MDSCs on cancer cells is poorly defined. Immunosuppressive MDSCs play an important role in tumor progression primarily because of their capability to promote immune-escape, angiogenesis, drug resistance and metastasis. However, their role in the bone marrow (BM), the primary MM site, is poorly understood. MM remains an incurable malignancy, and it is likely that the BM microenvironment protects MM against chemotherapy agents and the host immune system. A growing body of evidence suggests that host immune cells with a suppressive phenotype contribute to a myeloma immunosuppressive network. Among the known suppressor cells, MDSCs and T regulatory cells (Tregs) have been found to be significantly increased in myeloma patients and their levels correlate with disease stage and clinical outcome. Furthermore, it has been shown that MDSC can mediate suppression of myeloma-specific T-cell responses through the induction of T-cell anergy and Treg development in the MM microenvironment. Here, we review clinical correlations and the preclinical proof-of-principle data on the role of MDSCs in myeloma immunotolerance and highlight the mechanistically relevant MDSC-targeted compounds and their potential utility in a new approach for anti-myeloma therapy.

Lenalidomide enhances myeloma-specific T-cell responses in vivo and in vitro

Immunomodulation is an important part of lenalidomide's mode of action. We analyzed the impact of lenalidomide on T cells from patients with multiple myeloma during lenalidomide therapy in vivo and in patients with lenalidomide-refractory disease in vitro Patients enrolled in the German Speaking Myeloma Multicenter Group (GMMG) MM5 trial received a consolidation therapy with two cycles of lenalidomide after autologous stem cell transplantation (ASCT). Half of the study population continued treatment with lenalidomide maintenance therapy for 2 y, while the other patients received lenalidomide maintenance therapy until complete remission. We analyzed 58 patients with (n = 30) or without (n = 28) lenalidomide therapy and 12 patients refractory to lenalidomide with regards to their anti-myeloma-specific T-cell responses displayed by IFNγ, Granzyme B, and Perforin secretion. The immunophenotype of T-cells was investigated by flow cytometry. Significantly, more myeloma-specific T-cell responses were observed in patients during lenalidomide therapy, compared to patients without treatment. Furthermore, we found on T-cells from patients treated with lenalidomide a decreased CD45RA expression, indicating a maturated immunophenotype and a decreased expression of CD57, indicating functional T cells. An improved myeloma-specific T-cell response was observed in 6 out of 12 heavily pretreated patients (refractory to lenalidomide) after in vitro incubation with lenalidomide. Complementary to the results in vivo, lenalidomide decreased CD45RA expression on T cells in vitro.

A case of refractory multiple myeloma with proliferation of large granular lymphocytes by lenalidomide treatment and its association with clinical efficacy

A 72-year-old Japanese male was diagnosed as having monoclonal gammopathy of undetermined significance and was followed up without therapy. Three years later, the patient progressed to symptomatic multiple myeloma. Melphalan + prednisolone was administered as first-line chemotherapy for ~6 years. Since the patient was judged to exhibit refractory multiple myeloma, he subsequently received radiation therapy on the lumbar spine. The patient was enrolled in a clinical trial and received lenalidomide + lowdose dexamethasone (Rd) therapy. The patient achieved very good partial remission following four cycles of Rd. At this time, large granular lymphocytes (LGLs) increased to 25-40% of peripheral blood leukocytes, however, the LGLs were present in the blood (~8%) prior to lenalidomide treatment. By flow cytometry of surface antigens, it was revealed that the LGLs were positive for cluster of differnetiation (CD)2, 7, 8, 16, 56, and 57, and human leukocyte antigen-D related, however, were negative for CD3, 4 and 5, suggesting that these LGLs predominantly exhibited an natural killer (NK) cell phenotype. T-cell receptor β gene rearrangement was not detected by polymerase chain reaction. A ⁵¹Cr release assay was performed to investigate whether the NK cells actually possessed activity. A low level of M protein was sustained for ~15 months. This implied the enhancement of immune activation during lenalidomide treatment. The present case study suggested that LGL cells induced by lenalidomide may contribute to long-term restraint of myeloma cells. This immune system component may contribute to disease control.

Dendritic Cell-Based Cancer Immunotherapy against Multiple Myeloma: From Bench to Clinic

Although the introduction of stem cell transplantation and novel agents has improved survival, multiple myeloma (MM) is still difficult to cure. Alternative approaches are clearly needed to prolong the survival of patients with MM. Dendritic cell (DC) therapy is a very promising tool immunologically in MM. We developed a method to generate potent DCs with increased Th1 polarization and migration ability for inducing strong myeloma-specific cytotoxic T lymphocytes. In this review, we discuss how the efficacy of cancer immunotherapy using DCs can be improved in MM.

Treatment with lenalidomide induces immunoactivating and counter-regulatory immunosuppressive changes in myeloma patients

Lenalidomide activates the immune system, but the exact immunomodulatory mechanisms of lenalidomide in vivo are poorly defined. In an observational study we assessed the impact of lenalidomide on different populations of immune cells in multiple myeloma patients. Lenalidomide therapy was associated with increased amounts of a CD8(+) T cell subset, phenotypically staged between classical central memory T cells (TCM) and effector memory T cells (TEM), consequently termed TCM/TEM. The moderate expression of perforin/granzyme and phenotypical profile of these cells identifies them as not yet terminally differentiated, which makes them promising candidates for the anti-tumour response. In addition, lenalidomide-treated patients showed higher abundance of CD14(+) myeloid cells co-expressing CD15. This population was able to inhibit both CD4(+) and CD8(+) T cell proliferation in vitro and could thus be defined as a so far undescribed novel myeloid-derived suppressor cell (MDSC) subtype. We observed a striking correlation between levels of TCM/TEM, mature regulatory T cells (T(regs)) and CD14(+) CD15(+) MDSCs. In summary, lenalidomide induces both activating and inhibitory components of the immune system, indicating the existence of potential counter-regulatory mechanisms. These findings provide new insights into the immunomodulatory action of lenalidomide.

Targeted therapy for HM1.24 (CD317) on multiple myeloma cells

Multiple myeloma (MM) still remains an incurable disease, at least because of the existence of cell-adhesion mediated drug-resistant MM cells and/or continuous recruitment of presumed MM cancer stem cell-like cells (CSCs). As a new alternative treatment modality, immunological approaches using monoclonal antibodies (mAbs) and/or cytotoxic T lymphocytes (CTLs) are now attracting much attention as a novel strategy attacking MM cells. We have identified that HM1.24 [also known as bone marrow stromal cell antigen 2 (BST2) or CD317] is overexpressed on not only mature MM cells but also MM CSCs. We then have developed a humanized mAb to HM1.24 and defucosylated version of the mAb to adapt to clinical practice. Moreover, we have successfully induced HM1.24-specific CTLs against MM cells. The combination of these innovative therapeutic modalities may likely exert an anti-MM activity by evading the drug resistance mechanism and eliminating presumed CSCs in MM.

Lenalidomide consolidation and maintenance therapy after autologous stem cell transplant for multiple myeloma induces persistent changes in T-cell homeostasis

Whether the efficacy of lenalidomide in the treatment of multiple myeloma (MM) is due to direct tumor toxicity only or to additional immunomodulatory effects is unclear. We studied the effect of lenalidomide treatment on T-cell immune reconstitution in patients with MM who had undergone autologous peripheral blood stem cell transplant (ASCT). Twenty-nine newly diagnosed patients with MM received induction therapy followed by high-dose melphalan and ASCT. After ASCT, 11 patients received lenalidomide consolidation therapy for 2 months followed by maintenance therapy until disease progression. The remaining 18 patients received no treatment. Serial analysis of thymic output, as given by numbers of T-cell receptor excision circles (sjTRECs), and T-cell phenotyping was performed until 18 months post-ASCT. Lenalidomide impaired long-term thymic T-cell reconstitution, decreased CD4 + and CD8 + CD45RA + CCR7 - effector-terminal T-cell absolute counts and increased CD4 + CD25 + CD127 - /low regulatory T-cells. Lenalidomide consolidation and long-term maintenance therapy, administered post-ASCT, may have a potentially negative impact on immune surveillance.

Thalidomide maintenance therapy maturates the T cell compartment and compromises antigen-specific antitumor immunity in patients with multiple myeloma

Interferon (INF)-α was the maintenance treatment of choice after autologous stem cell transplantation in multiple myeloma in the past, but currently Thalidomide is commonly used. In this prospective study, the implications of the various types of maintenance therapy on the patients T cell pattern and activation status were assessed. T cells were analyzed for expression of surface molecules, cytokine secretion, the presence of regulatory T cells, and the specific activation against the multiple myeloma antigen HM1.24. T cells from 69 multiple myeloma patients were analyzed: 19 patients were treated with IFN-α; 26 were treated with Thalidomide; and 24 patients received no maintenance therapy. Specific T cell activation with an immunogenic HLA-A2(+)-restricted peptide from the myeloma-associated antigen HM1.24 was impaired in the Thalidomide group. In accordance with this observation, there was a trend toward a higher amount of regulatory T cells in the Thalidomide group. Furthermore, patients treated with IFN-α showed high rates of naive T cells, whereas a high rate of effector memory T cells was observed in the Thalidomide group. Importantly, after cessation of Thalidomide therapy, this effect was reversible in the CD8 compartment. In conclusion, Thalidomide maintenance therapy has profound implications on T cell pattern and activation status, which compromise antigen specific antitumor immunity.

Molecular action of lenalidomide in lymphocytes and hematologic malignancies

The immunomodulatory agent, lenalidomide, is a structural analogue of thalidomide approved by the US Food and Drug Administration for the treatment of myelodysplastic syndrome (MDS) and multiple myeloma (MM). This agent is also currently under active investigation for the treatment of chronic lymphocytic leukemia (CLL) and non-Hodgkin's lymphoma (NHL), as well as in drug combinations for some solid tumors and mantle cell lymphoma (MCL). Although treatment with lenalidomide has translated into a significant extension in overall survival in MM and MDS and has superior safety and efficacy relative to thalidomide, the mechanism of action as it relates to immune modulation remains elusive. Based on preclinical models and clinical trials, lenalidomide, as well as other structural thalidomide derivatives, enhances the proliferative and functional capacity of T-lymphocytes and amplifies costimulatory signaling pathways that activate effector responses and suppress inflammation. This paper summarizes our current understanding of T- and natural killer (NK) cell pathways that are modified by lenalidomide in hematopoietic neoplasms to inform future decisions about potential combination therapies.

Lenalidomide enhances anti-myeloma cellular immunity

Lenalidomide is an effective therapeutic agent for multiple myeloma that exhibits immunomodulatory properties including the activation of T and NK cells. The use of lenalidomide to reverse tumor-mediated immune suppression and amplify myeloma-specific immunity is currently being explored. In the present study, we examined the effect of lenalidomide on T-cell activation and its ability to amplify responses to a dendritic cell-based myeloma vaccine. We demonstrate that exposure to lenalidomide in the context of T-cell expansion with direct ligation of CD3/CD28 complex results in polarization toward a Th1 phenotype characterized by increased IFN-γ, but not IL-10 expression. In vitro exposure to lenalidomide resulted in decreased levels of regulatory T cells and a decrease in T-cell expression of the inhibitory marker, PD-1. Lenalidomide also enhanced T-cell proliferative responses to allogeneic DCs. Most significantly, lenalidomide treatment potentiated responses to the dendritic cell/myeloma fusion vaccine, which were characterized by increased production of inflammatory cytokines and increased cytotoxic lymphocyte-mediated lysis of autologous myeloma targets. These findings indicate that lenalidomide enhances the immunologic milieu in patients with myeloma by promoting T-cell proliferation and suppressing inhibitory factors, and thereby augmenting responses to a myeloma-specific tumor vaccine.

Expansion of polyfunctional HIV-specific T cells upon stimulation with mRNA electroporated dendritic cells in the presence of immunomodulatory drugs

Recently, it has been demonstrated that disease progression during HIV infection is not determined merely by the number of HIV-specific T cells but also by their quality (J. R. Almeida, et al., J. Exp. Med. 204:2473-2485, 2007; C. T. Berger, et al., J. Virol. 85:9334-9345, 2011; M. R. Betts, et al., Blood 107:4781-4789, 2006; V. V. Ganusov, et al., J. Virol. 85:10518-10528, 2011; P. Kiepiela, et al., Nat. Med. 13:46-53, 2007; and F. Pereyra, et al., J. Infect. Dis. 197:563-571, 2008). Therefore, strategies to specifically enhance or induce high-quality, HIV-specific T-cell responses are necessary to develop effective immune therapies. Thalidomide, lenalidomide, and pomalidomide have a strong capacity to boost immune responses and are therefore referred to as immunomodulatory drugs (IMiDs). We evaluated the effects of lenalidomide and pomalidomide on HIV-specific T cells. We found that the presence of IMiDs during in vitro T-cell stimulation with dendritic cells electroporated with Gag- or Nef-encoding mRNA resulted in higher numbers of cytokine-secreting HIV-specific CD8(+) T cells, particularly inducing polyfunctional HIV-specific CD8(+) T cells with an enhanced lytic capacity. Furthermore, CD8(+) T-cell responses were detected upon stimulation with lower antigenic peptide concentrations, and a higher number of Gag epitopes was recognized upon addition of IMiDs. Finally, IMiDs reduced the proliferation of the HIV-specific CD4(+) T cells while increasing the number of polyfunctional CD4(+) T cells. These results provide new information about the effects of IMiDs on antigen-specific T cells and suggest that these drugs increase the efficacy of immune therapies for infectious diseases and cancer.

Potent in vitro and in vivo activity of an Fc-engineered humanized anti-HM1.24 antibody against multiple myeloma via augmented effector function

HM1.24, an immunologic target for multiple myeloma (MM) cells, has not been effectively targeted with therapeutic monoclonal antibodies (mAbs). In this study, we investigated in vitro and in vivo anti-MM activities of XmAb5592, a humanized anti-HM1.24 mAb with Fc-domain engineered to significantly enhance FcγR binding and associated immune effector functions. XmAb5592 increased antibody-dependent cellular cytotoxicity (ADCC) several fold relative to the anti-HM1.24 IgG1 analog against both MM cell lines and primary patient myeloma cells. XmAb5592 also augmented antibody dependent cellular phagocytosis (ADCP) by macrophages. Natural killer (NK) cells became more activated by XmAb5592 than the IgG1 analog, evidenced by increased cell surface expression of granzyme B-dependent CD107a and MM cell lysis, even in the presence of bone marrow stromal cells. XmAb5592 potently inhibited tumor growth in mice bearing human MM xenografts via FcγR-dependent mechanisms, and was significantly more effective than the IgG1 analog. Lenalidomide synergistically enhanced in vitro ADCC against MM cells and in vivo tumor inhibition induced by XmAb5592. A single dose of 20 mg/kg XmAb5592 effectively depleted both blood and bone marrow plasma cells in cynomolgus monkeys. These results support clinical development of XmAb5592, both as a monotherapy and in combination with lenalidomide, to improve patient outcome of MM.