Current Cancer Drug Targets - Volume 17, Issue 9, 2017

High-dose therapy (HDT) followed by autologous stem cell transplantation (ASCT) remains the standard of care for patients younger than 65 years of age with multiple myeloma (MM). However, this therapeutic approach has undergone substantial advances in this last decade, mainly due to the introduction of new drugs such as thalidomide, lenalidomide and bortezomib. These new drugs, in different combinations, have shown to significantly increase response rates after induction therapy and ASCT. Moreover, the positive results obtained with these agents in consolidation and maintenance strategies after ASCT strongly support the concept of continuous therapy, whose ultimate goal is the long-term control of the disease and the improvement of outcome. Preliminary data from studies investigating next generation proteasome inhibitors, such as carfilzomib and ixazomib, used upfront as well as at subsequent therapeutic lines, demonstrate the possibility of achieving molecular remission in most of the patients. The deeper responses obtained with new drugcombinations questioned the role of ASCT, and large, ongoing, phase 3 trials will shed light on the role and the timing of ASCT.

Background: Multiple Myeloma (MM) cells inhibit the development of an effective anti- MM immune response via defects in T cell function, ineffective antigen presentation; reduced phagocytic capacity; natural killer and dendritic cell dysfunction; decreased responsiveness to IL-2 and defects in B cell immunity; upregulation of inhibitory pathways; and production of excessive proinflammatory cytokines. Moreover, immune cells including plasmacytoid dendritic cells and macrophages trigger tumor cell proliferation, survival, and drug resistance. The usefulness of immunotherapies in MM patients has first been supported by the identification of the graft-versus-myeloma effect in the context of allogeneic bone marrow (BM) transplantation. Subsequently, the inclusion of thalidomide and its derivatives, the Immunomodulatory Drugs (IMiDs) as well as of (immuno) proteasome inhibitors into MM regimens dramatically improved MM patients outcome during the last 15 years. Despite these unprecedented therapeutic advances MM remains an incurable disease. Objective: This article reviews novel immunotherapeutic approaches, which aim to restore the balance within the immunologic niche of the MM BM microenvironment. Method: A systematic search was conducted of the Pubmed Medline, Embase, and Cochrane Library databases for primary articles, as well as of conference abstracts (e.g., of the American Society of Hematology, the American Society of Clinical Oncology, the American Association of Cancer Research, the European Hematology Association, and the Multiple Myeloma Workshop), practice guidelines, and registries of clinical trials. Results: The inclusion of monoclonal antibodies, immune checkpoint inhibitors, chimeric antigen receptor-engineered (CAR) T cells, genetically engineered T cells, and vaccination, dendritic cellbased cancer vaccines in particular, into existing regimens is likely to significantly improve MM patient outcome in the near future. Conclusion: Given continuing efforts to target the immune niche within the bone marrow microenvironment we are confident that the rise of immunotherapies in MM will result in long-lasting responses in many of our patients within the next decade.

One of the great advances in the field of cancer therapy in recent years is the emergence of immune therapies. Immune therapies, especially immune checkpoint inhibitors, have shown promising results in pre-clinical models and clinical trials of solid tumors, such as melanoma, breast cancer and lung cancer. Therapeutic strategies targeting the immune microenvironment have also been applied to hematological malignancies such as multiple myeloma (MM), a plasma cell neoplasia characterized by clonal proliferation of malignant plasma cells mainly in the bone marrow (BM). MM is associated with both cellular and humoral immune deficiencies, indicating that the evolution of the disease from a precursor state (monoclonal gammopathy of undetermined significance (MGUS) and smoldering MM (sMM)) is associated with an immunosuppressive milieu that fosters immune escape and tumor growth. Despite significant advances in treatment, MM is mostly an incurable disease. Therefore, it is vital to develop novel therapeutic agents that not only target the MM clone itself but also the MM immune microenvironment. However, the complexity of the BM microenvironment and heterogeneity of tumor cell clones make it a difficult task for developing appropriate immune therapies of MM. In this article, we review the current knowledge of the interaction between malignant plasma cells and the bone marrow immune microenvironment during disease progression.

Multiple myeloma (MM) is an incurable plasma cell neoplasm accounting for about 10% of all hematologic malignancies. Recently, emerging evidence is disclosing the complexity of bone marrow interactions between MM cells and infiltrating immune cells, which have been reported to promote proliferation, survival and drug resistance of tumor cells. MicroRNAs (miRNAs) are small non-coding RNA molecules with regulatory functions in the cell, whose expression has predictive and prognostic value in different malignancies. MiRNAs are gaining increasing interest due to their capability to polarize the immune-response through different mechanisms, which include the molecular reprogramming of immune cells. This characteristic, together with the antitumor activity of miRNA mimics or inhibitors, make the miRNA network an attractive area of investigation for novel anti-MM therapeutic approaches. In this review, we will discuss the recent advances in the understanding of the interplay between MM cells and bone marrow resident immune cells, with special focus on the molecular and functional changes induced by miRNA network modulation. We will finally indicate potential targets for therapeutic intervention.

Background: Patients with Multiple Myeloma suffer from dysregulation of the immune system and new therapeutic options targeting the immune systems such as monoclonal antibodies or specific Cell therapy such as CAR-T cells have entered clinical practice, but the exhausted immune system hampered a more effective immunotherapy. Targeting the immunological dysfunction in the microenviroment might be a potential target for immune-mediated therapies. Method: Here we review the current literature and knowledge about the programmed death 1 (PD-1) receptor which is expressed on the surface of exhausted T and B cells and its ligand PD-L1 is expressed on myeloma cells and inhibits T cell-mediated apoptosis. Results: The programmed death 1 (PD-1) receptor is expressed on the surface of exhausted T and B cells and its ligand PD-L1 is expressed on myeloma cells and inhibits Tcell-mediated apoptosis. Inhibiting such “checkpoint” by monoclonal antibodies recently has been shown high activity in solid tumors and malignant lymphomas. In patients with multiple myelomaPD-L1 is overexpressed on myeloma cells and PD1 on T-cells suggesting an active role of PD-1/PD-L1 in the immunosuppressive microenvironment. Conclusion: Immunotherapies using anti-PD-1/PD-L1 strategies are a promising treatment options for patients with multiple myeloma.

Background: Multiple myeloma (MM) is a hematological cancer caused by a proliferation of clonal plasma cells, leading to anemia, renal failure, hypercalcemia and destructive bone lesions resulting in significant morbidity. The overall survival has significantly improved with the incorporation of immunomodulatory drugs (IMiDs) and proteasome inhibitors (PI). Objective: Here we provide a comprehensive review on IMiDs including molecular mechanisms, recent advances in therapeutic applications and management of toxicities in the treatment of MM. Methods: Relevant publications in peer reviewed journals were retrieved by a selective search of PubMed. Systemic reviews, meta-analyses, randomized controlled trials, and treatment recommendations were reviewed and are summarized here. Results: Thalidomide, a first generation IMiD, is associated with significant toxicity in older patients. Lenalidomide, a more potent second generation IMiD with fewer side effects than thalidomide, is commonly used in newly-diagnosed multiple myeloma, relapsed refractory myeloma and as maintenance therapy after autologous stem cell transplantation (ASCT). Pomalidomide, a third generation IMiD, is 10 times more potent than lenalidomide and has shown impressive results in relapsed MM patients and in those refractory to both lenalidomide and bortezomib. Conclusion: The clinical use of IMiDs in MM has significantly improved long-term survival and quality of life. Future studies are looking into novel biomarkers predictive of outcome in MM and new combinations of lenalidomide and pomalidomde with PI, monoclonal antibodies, immune checkpoint blockers and several other chemotherapies.