PD-1/PD-L1 inhibitors in multiple myeloma: The present and the future

Integration of protein L-immobilized epoxy magnetic bead capture with LC-MS/MS for therapeutic monoclonal antibody quantification in serum

In recent years, there has been a growing interest in the thriving monoclonal antibody (mAb) industry due to the wide utilization of mAbs in clinical therapies. Robust and accurate bioanalytical methods are required to enable fast quantification of mAbs in biological matrices, especially in the context of pharmacokinetics (PKs)/pharmacodynamics (PDs) and therapeutic drug monitoring (TDM) studies. In this investigation, we presented a novel immuno-magnetic capture coupled with a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method designed for the quantification of immunoglobulin G-kappa-based mAbs in biological fluids. The immunoaffinity absorbent for mAb drug purification was meticulously crafted by immobilizing protein L onto monosize, magnetic poly(glycidyl methacrylate) (m-pGMA) beads, synthesized through dispersion polymerization. The microspheres were acquired with an average size of 1.6 μm, and the optimal binding of mAbs from the aqueous mAb solution was determined to be 45.82 mg g-1. The quantification of mAbs in 10 μL serum samples was achieved through affinity purification using m-pGMA@protein L beads (employing rituximab as an internal standard (IS)), on-bead reduction, and rapid tryptic digestion. Remarkably, the entire process, taking less than 2.5 hours, held significant potential for simplifying pretreatment procedures and minimizing analytical time. Furthermore, the developed method underwent validation in accordance with the European Medicines Agency (EMA) guidelines. The assay demonstrated commendable linearity within the 2-400 μg mL-1 range for both daratumumab and pembrolizumab. Intra- and inter-assay coefficients of variation fell within the range of 0.7% to 13.4%, meeting established acceptance criteria. Other validation parameters also conformed to regulatory standards. Ultimately, the efficacy of the method was substantiated in a pharmacokinetic study following a single-dose intravenous administration to mice, underscoring its applicability and reliability in real-world scenarios.

Safety and efficacy of belantamab mafodotin with pembrolizumab in patients with relapsed or refractory multiple myeloma

BACKGROUND

Belantamab mafodotin (belamaf) has shown promising antimyeloma activity in relapsed or refractory multiple myeloma (RRMM) as a single agent. It was hypothesized that its multimodal activity may be enhanced by programmed cell death protein 1 pathway inhibition and activation of T cell-mediated antitumor responses. This study investigated the efficacy and safety of belamaf with pembrolizumab in patients with RRMM.

METHODS

DREAMM-4 (NCT03848845) was an open-label, single-arm, phase 1/2 study divided into dose-escalation (part 1) and dose-expansion (part 2) phases. Patients were ≥18 years old with ≥3 prior lines of therapy including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 agent. Patients received belamaf (2.5 or 3.4 mg/kg, part 1; 2.5 mg/kg, part 2) and 200 mg pembrolizumab for ≤35 cycles.

RESULTS

Of 41 enrolled patients, 34 (n = 6 part 1, n = 28 part 2) who received 2.5 mg/kg belamaf plus pembrolizumab were included in this final analysis. Sixteen patients (47%) achieved an overall response. Minimal residual disease negativity was achieved in three of 10 patients who had very good partial response or better. Five of eight patients who had prior anti-B-cell maturation antigen therapy achieved partial response or better, including two who had B-cell maturation antigen-refractory disease. Common grade ≥3 adverse events were keratopathy (38%) and thrombocytopenia (29%). Despite belamaf-related ocular events, quality-of-life measures remained stable over time. No new safety signals were observed.

CONCLUSIONS

The results of DREAMM-4 demonstrated clinical activity and a favorable safety profile of belamaf plus pembrolizumab in patients with RRMM. This trial is registered at www.

CLINICALTRIALS

gov as NCT03848845.

Immune checkpoint inhibitors for multiple myeloma immunotherapy

Multiple myeloma (MM) is related to immune disorders, recent studys have revealed that immunotherapy can greatly benefit MM patients. Immune checkpoints can negatively modulate the immune system and are closely associated with immune escape. Immune checkpoint-related therapy has attracted much attention and research in MM. However, the efficacy of those therapies need further improvements. There need more thoughts about the immune checkpoint to translate their use in clinical work. In our review, we aggregated the currently known immune checkpoints and their corresponding ligands, further more we propose various ways of potential translation applying treatment based on immune checkpoints for MM patients.

Toxicity of Immune-Checkpoint Inhibitors in Hematological Malignancies

Immune checkpoint inhibitors (ICIs), especially those targeting the programmed-death 1 (PD-1) receptor and its ligands, have become indispensable agents in solid tumor anti-cancer therapy. Concerning hematological malignancies, only nivolumab and pembrolizumab have been approved for the treatment of relapsed and refractory classical Hodgkin lymphoma and primary mediastinal large B cell lymphoma to date. Nevertheless, clinical research in this field is very active. The mechanism of action of ICIs is based on unblocking the hindered immune system to recognize and eliminate cancer cells, but that also has its costs in the form of ICI-specific immune related adverse events (irAEs), which can affect any organ system and can even be lethal. In this article, we have reviewed all prospective blood cancer clinical trials investigating ICIs (both monotherapy and combination therapy) with available toxicity data with the purpose of determining the incidence of irAEs in this specific setting and to offer a brief insight into their management, as the use of immune checkpoint blockade is not so frequent in hemato-oncology.

Bone marrow-derived mesenchymal stem cells inhibit CD8+ T cell immune responses via PD-1/PD-L1 pathway in multiple myeloma

High expression of the inhibitory receptor programmed cell death ligand 1 (PD-L1) on tumor cells and tumor stromal cells have been found to play a key role in tumor immune evasion in several human malignancies. However, the expression of PD-L1 on bone marrow mesenchymal stem cells (BMSCs) and whether the programmed cell death 1 (PD-1)/PD-L1 signal pathway is involved in the BMSCs versus T cell immune response in multiple myeloma (MM) remains poorly defined. In this study, we explored the expression of PD-L1 on BMSCs from newly diagnosed MM (NDMM) patients and the role of PD-1/PD-L1 pathway in BMSC-mediated regulation of CD8⁺ T cells. The data showed that the expression of PD-L1 on BMSCs in NDMM patients was significantly increased compared to that in normal controls (NC) (18·81 ± 1·61 versus 2·78± 0·70%; P < 0·001). Furthermore, the PD-1 expression on CD8⁺ T cells with NDMM patients was significantly higher than that in normal controls (43·22 ± 2·98 versus 20·71 ± 1·08%; P < 0·001). However, there was no significant difference in PD-1 expression of CD4⁺ T cells and natural killer (NK) cells between the NDMM and NC groups. Additionally, the co-culture assays revealed that BMSCs significantly suppressed CD8⁺ T cell function. However, the PD-L1 inhibitor effectively reversed BMSC-mediated suppression in CD8⁺ T cells. We also found that the combination of PD-L1 inhibitor and pomalidomide can further enhance the killing effect of CD8⁺ T cells on MM cells. In summary, our findings demonstrated that BMSCs in patients with MM may induce apoptosis of CD8⁺ T cells through the PD-1/PD-L1 axis and inhibit the release of perforin and granzyme B from CD8⁺ T cells to promote the immune escape of MM.

The perspectives of interleukin-10 in the pathogenesis and therapeutics of multiple myeloma

Multiple myeloma (MM) is typically featured by the increased levels of inflammatory cytokines in the neoplastic plasma cells (PCs) producing monoclonal immunoglobulin. PCs proliferate in the bone marrow, which will lead to extensive skeletal destruction with osteolytic lesions, osteopenia, or pathologic fractures. The diagnostic biology of MM has progressed from morphology and low-sensitivity protein analysis into multiomics-based high-throughput readout, whereas therapeutics has evolved from single active agent to potential active drug combinations underlying precision medicine. Many studies have focused on the cytokine networks that control growth, progression, and dissemination of the disease. The complexity of cytokines in MM development remains to be elucidated comprehensively. Apart from knowing that interleukin (IL)-6 is important in the pathogenesis of MM, it has been shown that IL-6 is a paracrine factor supplied by the microenvironment comprising of those cells from the myeloid compartment. Due to IL-10 was considered an immunosuppressive cytokine to promote cancer escape from immune surveillance, the role of IL-10 in this regard has been underestimated although recent advances have reported that IL-10 induces both PC proliferation and angiogenesis in MM. In addition, cumulative studies have suggested that IL-10 plays an important role in the induction of chemoresistance in many cancers; a virtual requirement of autocrine IL-10 for MM cells to escape from an IL-6-dependent proliferation loop was implicated. In this review, we summarize the available information to elucidate a new understanding of the molecular and functional roles of IL-10 in MM.

Targeting NF-κB Signaling for Multiple Myeloma

Multiple myeloma (MM) is the second most common hematologic malignancy in the world. Even though survival rates have significantly risen over the past years, MM remains incurable, and is also far from reaching the point of being managed as a chronic disease. This paper reviews the evolution of MM therapies, focusing on anti-MM drugs that target the molecular mechanisms of nuclear factor kappa B (NF-κB) signaling. We also provide our perspectives on contemporary research findings and insights for future drug development.

Potent anti-myeloma efficacy of dendritic cell therapy in combination with pomalidomide and programmed death-ligand 1 blockade in a preclinical model of multiple myeloma

Dendritic cell (DC)-based vaccines are recognized as a promising immunotherapeutic strategy against cancer; however, the efficacy of immunotherapy with DCs is controlled via immune checkpoints, such as programmed death-ligand 1 (PD-L1). PD-L1 expressed on DC and tumor cells binds to programmed death-1 (PD-1) receptors on the activated T cells, which leads to the inhibition of cytotoxic T cells. Blocking of PD-L1 on DC may lead to improve the efficacy of DC therapy for cancer. Here we demonstrated that DC vaccination in combination with pomalidomide and programmed death-ligand 1 (PD-L1) blockade inhibited tumor growth of a multiple myeloma (MM) mouse model. DCs + pomalidomide with dexamethasone + PD-L1 blockade significantly inhibited immune immunosuppressive factors and promoted proportions of immune effector cells in the spleen and tumor microenvironment. Additionally, functional activities of cytotoxic T lymphocytes and NK cells in spleen were enhanced by DCs + pomalidomide with dexamethasone + PD-L1 blockade. Taken together, this study identifies a potential new therapeutic approach for the treatment of MM. These results also provide a foundation for the future development of immunotherapeutic modalities to inhibit tumor growth and restore immune function in MM.

A Comprehensive Biological and Clinical Perspective Can Drive a Patient-Tailored Approach to Multiple Myeloma: Bridging the Gaps between the Plasma Cell and the Neoplastic Niche

There is a broad spectrum of diseases labeled as multiple myeloma (MM). This is due not only to the composite prognostic risk factors leading to different clinical outcomes and responses to treatments but also to the composite tumor microenvironment that is involved in a vicious cycle with the MM plasma cells. New therapeutic strategies have improved MM patients' chances of survival. Nevertheless, certain patients' subgroups have a particularly unfavorable prognosis. Biological stratification can be subdivided into patient, disease, or therapy-related factors. Alternatively, the biological signature of aggressive disease and dismal therapeutic response can promote a dynamic, comprehensive strategic approach, better tailoring the clinical management of high-risk profiles and refractoriness to therapy and taking into account the role played by the MM milieu. By means of an extensive literature search, we have reviewed the state-of-the-art pathophysiological insights obtained from translational investigations of the MM-bone marrow microenvironment. A good knowledge of the MM niche pathophysiological dissection is crucial to tailor personalized approaches in a bench-bedside fashion. The discussion in this review pinpoints two main aspects that appear fundamental in order to gain novel and definitive results from the biology of MM. A systematic knowledge of the plasma cell disorder, along with greater efforts to face the unmet needs present in MM evolution, promises to open a new therapeutic window looking out onto the plethora of scientific evidence about the myeloma and the bystander cells.

Programmed cell death ligand-1: A dynamic immune checkpoint in cancer therapy

Antibody-based immunotherapies play a pivotal role in cancer research with efficient achievements in tumor suppression. Tumor survival is assisted by modulation of immune checkpoints to create imbalances between immune cells and cancer cell's environment. The modulation results in T-cell signal inhibition ultimately inert its proliferation and activation against various tumor cells. PD-L1, a 40 kDa transmembrane protein of B7 family, binds with PD-1 on the membrane of T cells which results in inhibition of T-cell proliferation and activation. PD-L1/PD-1 pathway has generated novel target sites for antibodies that can block PD-L1/PD-1 interactions. The blockage results in T-cell proliferation and tumor cell suppression. The PD-L1 immune checkpoint strategies' development, expression and regulations, signal inhibitions, and developmental stages of PD-L1/PD-1 antibodies are briefly discussed here in this review. All this information will provide a base for new therapeutic development against PD-L1 and PD-1 immune checkpoint interactions and will make available promising treatment options.

Identifying and treating candidates for checkpoint inhibitor therapies in multiple myeloma and lymphoma

Introduction: One of the hallmarks of cancerogenesis is the ability of tumor cells to evade the immune system. They can achieve it by abusing inhibitory immune checkpoint pathways, which, under normal circumstances, maintain peripheral tolerance during infection. Immune checkpoint inhibitors, especially anti-PD-1/PD-L1 monoclonal antibodies, currently represent a widely discussed treatment option not only in solid oncology, but in hematology-oncology as well.Areas covered: The manuscript is focused on clinical research concerning PD-1/PD-L1 blockade in lymphoma and multiple myeloma in order to identify the patients who would profit the most from this treatment modality. The authors reviewed articles on the topic on PubMed and relevant clinical trials on clinicaltrials.gov before October 2019.Expert opinion: So far, nivolumab and pembrolizumab have been approved for treating patients with relapsed/refractory classical Hodgkin lymphoma and primary mediastinal B cell lymphoma. Nevertheless, monotherapy alone is not curative and a combinational approach is needed. Modern treatment strategies and combinations are comprehensively summarized in this manuscript. There is no approved immune checkpoint inhibitor for the multiple myeloma indication. Although the combination of PD-1/PD-L1 inhibitors with immunomodulatory agents initially seemed promising, unexpected immune related toxicities have stopped any further development. Novel strategies and more potent combinations in myeloma and lymphoma are further discussed in the manuscript.

Frequent methylation of the tumour suppressor miR-1258 targeting PDL1: implication in multiple myeloma-specific cytotoxicity and prognostification

miR-1258 is localised to the first intron of ZNF385B at chromosome 2q31.3. miR-1258 promoter methylation was studied in 147 samples including 10 normal buffy coat, eight normal bone marrow plasma cells, 16 human myeloma cell lines (HMCLs), 20 MGUS, 63 diagnostic myeloma, and 30 relapsed myeloma samples by methylation-specific PCR. In myeloma lines, miR-1258 methylation, verified by pyrosequencing, was detected in 62·5% HMCLs but not normal controls, and expression of miR-1258 correlated with that of ZNF385B. 5-Aza-2'-deoxycytidine resulted in promoter demethylation and ZNF385B/miR-1258 re-expression. Luciferase assay confirmed programmed cell death ligand-1 (PDL1) as a direct target of miR-1258. Over-expression of miR-1258 in completely methylated myeloma cells led to reduced cellular proliferation and enhanced apoptosis, hence a tumour suppressor role, in addition to repression of PDL1. In primary samples, miR-1258 methylation, with lower expression of miR-1258, was detected in 49·2% diagnostic myeloma, imparting an inferior PFS (P = 0·034) in addition to 50·0% relapsed myeloma but not MGUS. Therefore, miR-1258 is a tumour suppressor miRNA co-regulated with its host gene, and frequently hypermethylated in active myeloma instead of MGUS, hence acquired during myeloma progression. Methylation-mediated miR-1258 silencing led to overexpression of PDL1 and inferior PFS, implicating miR-1258 in the modulation of myeloma-specific cytotoxicity.

Daratumumab prevents programmed death ligand-1 expression on antigen-presenting cells in de novo multiple myeloma

Background

Daratumumab (Dara), an anti‐CD38 monoclonal antibody, has an immunologic mechanism of action through targeting of CD38 expressing immune cells in patients with multiple myeloma (MM). Furthermore, it was recently shown that CD38 upregulation in tumors, is a major mechanism of acquired resistance to antiprogrammed cell death 1 (PD‐1)/programmed cell death ligand 1 (PD‐L1). Therefore, we decided to evaluate the immunomodulatory effects of CD38 blockade by Dara on the PD‐L1 expressing immune cells.

Methods

We analyzed CD38 and PD‐L1 expression on immune cells at different time points in 18 newly diagnosed MM receiving bortezomib, lenalidomide and dexamethasone, with or without Dara.

Results

We first confirmed that CD38 is widely expressed on immune cells, with the strongest expression on plasmacytoid dendritic cells (pDC). Furthermore, Dara induces a strong depletion of pDC in addition to the well‐known rapid depletion of natural killer cells. Finally, we found that PD‐L1 expression on antigen‐presenting cells (APC) increases with MM treatment in patients that did not received Dara, while addition of Dara prevents this increase.

Conclusion

Overall, our results suggest new mechanisms of action of Dara through depletion of pDC and prevention of PD‐L1 upregulation expression on APC. Our finding provides new evidences for development of therapeutic strategies targeting both CD38 and PD‐L1/PD‐1 pathway in patients with MM.

Pembrolizumab plus lenalidomide and dexamethasone for patients with treatment-naive multiple myeloma (KEYNOTE-185): a randomised, open-label, phase 3 trial

BACKGROUND

Lenalidomide and dexamethasone has been a standard of care in transplant-ineligible patients with newly diagnosed multiple myeloma. The addition of a third drug to the combination is likely to improve treatment efficacy. KEYNOTE-185 assessed the efficacy and safety of lenalidomide and dexamethasone with and without pembrolizumab in patients with previously untreated multiple myeloma. Here, we present the results of an unplanned interim analysis done to assess the benefit-risk of the combination at the request of the US Food and Drug Administration (FDA).

METHODS

KEYNOTE-185 was a randomised, open-label, phase 3 trial done at 95 medical centres across 15 countries (Australia, Canada, France, Germany, Ireland, Israel, Italy, Japan, New Zealand, Norway, Russia, South Africa, Spain, UK, and USA). Transplantation-ineligible patients aged 18 years and older with newly diagnosed multiple myeloma, Eastern Cooperative Oncology Group performance status of 0 or 1, and who were treatment naive were enrolled, and randomly assigned 1:1 to receive either pembrolizumab plus lenalidomide and dexamethasone or lenalidomide and dexamethasone alone using an interactive voice or integrated web response system. Patients received oral lenalidomide 25 mg on days 1-21 and oral dexamethasone 40 mg on days 1, 8, 15, and 22 of repeated 28-day cycles, with or without intravenous pembrolizumab 200 mg every 3 weeks. The primary endpoint was progression-free survival, which was investigator-assessed because of early trial termination. Efficacy was analysed in all randomly assigned patients and safety was analysed in all patients who received at least one dose of study drug. This trial is registered at ClinicalTrials.gov, number NCT02579863, and it is closed for accrual.

FINDINGS

Between Jan 7, 2016, and June 9, 2017, 301 patients were randomly assigned to the pembrolizumab plus lenalidomide and dexamethasone group (n=151) or the lenalidomide and dexamethasone group (n=150). On July 3, 2017, the FDA decided to halt the study because of the imbalance in the proportion of death between groups. At database cutoff (June 2, 2017), with a median follow-up of 6·6 months (IQR 3·4-9·6), 149 patients in the pembrolizumab plus lenalidomide and dexamethasone group and 145 in the lenalidomide and dexamethasone group had received their assigned study drug. Median progression-free survival was not reached in either group; progression-free survival estimates at 6-months were 82·0% (95% CI 73·2-88·1) versus 85·0% (76·8-90·5; hazard ratio [HR] 1·22; 95% CI 0·67-2·22; p=0·75). Serious adverse events were reported in 81 (54%) patients in the pembrolizumab plus lenalidomide and dexamethasone group versus 57 (39%) patients in the lenalidomide and dexamethasone group; the most common serious adverse events were pneumonia (nine [6%]) and pyrexia (seven [5%]) in the pembrolizumab plus lenalidomide and dexamethasone group and pneumonia (eight [6%]) and sepsis (two [1%]) in the lenalidomide and dexamethasone group. Six (4%) treatment-related deaths occurred in the pembrolizumab plus lenalidomide and dexamethasone group (cardiac arrest, cardiac failure, myocarditis, large intestine perforation, pneumonia, and pulmonary embolism) and two (1%) in the lenalidomide and dexamethasone group (upper gastrointestinal haemorrhage and respiratory failure).

INTERPRETATION

The results from this unplanned, FDA-requested, interim analysis showed that the benefit-risk profile of pembrolizumab plus lenalidomide and dexamethasone is unfavourable for patients with newly diagnosed, previously untreated multiple myeloma. Long-term safety and survival follow-up is ongoing.

FUNDING

Merck Sharp & Dohme, a subsidiary of Merck & Co, Inc (Kenilworth, NJ, USA).

Dose Adjustment Helps Obtain Better Outcomes in Multiple Myeloma Patients with Bortezomib, Melphalan, and Prednisolone (VMP) Treatment

Objective

Multiple myeloma (MM) has a better survival outcome because of the development of drugs. However, equivalent outcomes cannot be expected from the same drug. Therefore, how the treatment schedule is managed is important. We analyzed VMP (bortezomib, melphalan, and prednisolone) data to determine an effective treatment strategy.

Materials and Methods

We collected the data of 59 patients who were newly diagnosed with MM from January 2012 to April 2017 using electronic medical records. We analyzed baseline characteristics, responses, dose reductions, and survival.

Results

The overall response rate was 86.5% [complete response (CR): 32.2%, very good partial response (VGPR): 37.3%]. The median progression-free survival was 33.6 months and the 5-year overall survival rate was 70%. There were significant better progression-free survival outcomes between CR and non-CR for each of the 4 cycles. Of the four patients who achieved CR after the first cycle, none have had disease progression as of yet. We divided patients into two groups according to the median dose (52.1 mg/m²) and we found no differences between the high-dose and low-dose groups. About 78% of patients completed 9-cycle schedules and 84% patients experienced dose reduction, mostly for reasons of non-hematologic toxicities.

Conclusion

Active dose reduction helped to continue treatment and it increased the opportunity to be exposed to drugs. In the end, it resulted in improved outcome.

Therapeutic Modulation of Autophagy in Leukaemia and Lymphoma

Haematopoiesis is a tightly orchestrated process where a pool of hematopoietic stem and progenitor cells (HSPCs) with high self-renewal potential can give rise to both lymphoid and myeloid lineages. The HSPCs pool is reduced with ageing resulting in few HSPC clones maintaining haematopoiesis thereby reducing blood cell diversity, a phenomenon called clonal haematopoiesis. Clonal expansion of HSPCs carrying specific genetic mutations leads to increased risk for haematological malignancies. Therefore, it comes as no surprise that hematopoietic tumours develop in higher frequency in elderly people. Unfortunately, elderly patients with leukaemia or lymphoma still have an unsatisfactory prognosis compared to younger ones highlighting the need to develop more efficient therapies for this group of patients. Growing evidence indicates that macroautophagy (hereafter referred to as autophagy) is essential for health and longevity. This review is focusing on the role of autophagy in normal haematopoiesis as well as in leukaemia and lymphoma development. Attenuated autophagy may support early hematopoietic neoplasia whereas activation of autophagy in later stages of tumour development and in response to a variety of therapies rather triggers a pro-tumoral response. Novel insights into the role of autophagy in haematopoiesis will be discussed in light of designing new autophagy modulating therapies in hematopoietic cancers.

Treatment of Lymphoid and Myeloid Malignancies by Immunomodulatory Drugs

Thalidomide and its derivatives (lenalidomide, pomalidomide, avadomide, iberdomide hydrochoride, CC-885 and CC-90009) form the family of immunomodulatory drugs (IMiDs). Lenalidomide (CC5013, Revlimid®) was approved by the US FDA and the EMA for the treatment of multiple myeloma (MM) patients, low or intermediate-1 risk transfusion-dependent myelodysplastic syndrome (MDS) with chromosome 5q deletion [del(5q)] and relapsed and/or refractory mantle cell lymphoma following bortezomib. Lenalidomide has also been studied in clinical trials and has shown promising activity in chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL). Lenalidomide has anti-inflammatory effects and inhibits angiogenesis. Pomalidomide (CC4047, Imnovid® [EU], Pomalyst® [USA]) was approved for advanced MM insensitive to bortezomib and lenalidomide. Other IMiDs are in phases 1 and 2 of clinical trials. Cereblon (CRBN) seems to have an important role in IMiDs action in both lymphoid and myeloid hematological malignancies. Cereblon acts as the substrate receptor of a cullin-4 really interesting new gene (RING) E3 ubiquitin ligase CRL4CRBN. This E3 ubiquitin ligase in the absence of lenalidomide ubiquitinates CRBN itself and the other components of CRL4CRBN complex. Presence of lenalidomide changes specificity of CRL4CRBN which ubiquitinates two transcription factors, IKZF1 (Ikaros) and IKZF3 (Aiolos), and casein kinase 1α (CK1α) and marks them for degradation in proteasomes. Both these transcription factors (IKZF1 and IKZF3) stimulate proliferation of MM cells and inhibit T cells. Low CRBN level was connected with insensitivity of MM cells to lenalidomide. Lenalidomide decreases expression of protein argonaute-2, which binds to cereblon. Argonaute-2 seems to be an important drug target against IMiDs resistance in MM cells. Lenalidomide decreases also basigin and monocarboxylate transporter 1 in MM cells. MM cells with low expression of Ikaros, Aiolos and basigin are more sensitive to lenalidomide treatment. The CK1α gene (CSNK1A1) is located on 5q32 in commonly deleted region (CDR) in del(5q) MDS. Inhibition of CK1α sensitizes del(5q) MDS cells to lenalidomide. CK1α mediates also survival of malignant plasma cells in MM. Though, inhibition of CK1α is a potential novel therapy not only in del(5q) MDS but also in MM. High level of full length CRBN mRNA in mononuclear cells of bone marrow and of peripheral blood seems to be necessary for successful therapy of del(5q) MDS with lenalidomide. While transfusion independence (TI) after lenalidomide treatment is more than 60% in MDS patients with del(5q), only 25% TI and substantially shorter duration of response with occurrence of neutropenia and thrombocytopenia were achieved in lower risk MDS patients with normal karyotype treated with lenalidomide. Shortage of the biomarkers for lenalidomide response in these MDS patients is the main problem up to now.

Update on PD-1/PD-L1 Inhibitors in Multiple Myeloma

The treatment of cancer, especially of various types of solid tumors, has been revolutionized by the blockade of the PD-1/PD-L1 pathway by immune checkpoint inhibitors. Their success amongst hematologic malignancies, however, has been limited so far to the treatment of classic Hodgkin's lymphoma, which portrays a typical overexpression of PD-1 ligands (PD-L1, PD-L2) as a consequence of changes in chromosome 9p24.1. Their current application in multiple myeloma (MM) is rather uncertain, as discordant results have been reported by distinct research groups concerning especially the expression of PD-1/PD-L1 molecules on malignant plasma cells or on the responsible immune effector cell populations, respectively. In MM it seems that an approach based on combination treatment might be appropriate as unsatisfactory results have been yielded by monotherapy with PD-1/PD-L1 inhibitors. Immunomodulatory drugs, which are the current cornerstone of MM treatment, are the most logical partners as they possess many possibly synergistic effects. Nevertheless, the initially optimistic results have become disappointing due to the excessive and unpredictable toxicity of the combination of pembrolizumab with lenalidomide or pomalidomide. The FDA has suspended or put on hold several phase 3 trials in relapsed as well as in newly diagnosed myeloma patients. There are also other potentially synergistic and promising combinations, such as the anti-CD38 monoclonal antibody daratumumab, irradiation, etc. Not only the effective partner but also the correct timing of the initiation of the PD-1/PD-L1 inhibitors treatment seems to be of utmost importance. These strategies are currently being examined in various stages of myeloma such as during consolidation post autologous stem cell transplantation, targeting minimal residual disease or even in high risk smoldering myeloma.

Trial watch: Peptide-based vaccines in anticancer therapy

Peptide-based anticancer vaccination aims at stimulating an immune response against one or multiple tumor-associated antigens (TAAs) following immunization with purified, recombinant or synthetically engineered epitopes. Despite high expectations, the peptide-based vaccines that have been explored in the clinic so far had limited therapeutic activity, largely due to cancer cell-intrinsic alterations that minimize antigenicity and/or changes in the tumor microenvironment that foster immunosuppression. Several strategies have been developed to overcome such limitations, including the use of immunostimulatory adjuvants, the co-treatment with cytotoxic anticancer therapies that enable the coordinated release of damage-associated molecular patterns, and the concomitant blockade of immune checkpoints. Personalized peptide-based vaccines are also being explored for therapeutic activity in the clinic. Here, we review recent preclinical and clinical progress in the use of peptide-based vaccines as anticancer therapeutics.Abbreviations: CMP: carbohydrate-mimetic peptide; CMV: cytomegalovirus; DC: dendritic cell; FDA: Food and Drug Administration; HPV: human papillomavirus; MDS: myelodysplastic syndrome; MHP: melanoma helper vaccine; NSCLC: non-small cell lung carcinoma; ODD: orphan drug designation; PPV: personalized peptide vaccination; SLP: synthetic long peptide; TAA: tumor-associated antigen; TNA: tumor neoantigen

Trial Watch: Oncolytic viro-immunotherapy of hematologic and solid tumors

Oncolytic viruses selectively target and kill cancer cells in an immunogenic fashion, thus supporting the establishment of therapeutically relevant tumor-specific immune responses. In 2015, the US Food and Drug Administration (FDA) approved the oncolytic herpes simplex virus T-VEC for use in advanced melanoma patients. Since then, a plethora of trials has been initiated to assess the safety and efficacy of multiple oncolytic viruses in patients affected with various malignancies. Here, we summarize recent preclinical and clinical progress in the field of oncolytic virotherapy.

Checkpoint inhibition in the treatment of multiple myeloma: A way to boost innate-like T cell anti-tumor function?

Multiple myeloma (MM) is a progressive monoclonal B cell malignancy, for which survival and progression largely relies on the crosstalk of tumor cells with the bone marrow (BM) microenvironment, inducing immune escape, angiogenesis, bone destruction and drug resistance. Despite great therapeutic advances, most of the MM patients still relapse and remain incurable. Over the past years, immunotherapy has emerged as a new field in cancer therapy. Here, the immune cells of the patients themselves are activated to target the tumor cells. In MM, several effector cells of the immune system are present in the BM microenvironment; unfortunately, they are mostly all functionally impaired. In this review, we focus on the role of innate-like T cells in MM, particularly CD1d- and MR1- restricted T cells such as respectively invariant natural killer T (iNKT) cells and mucosal associated invariant T (MAIT) cells. These cells have the capacity upon activation to rapidly release copious amounts of cytokines affecting a wide range of innate and adaptive immune responses, and could therefore play a key protective role in anti-tumor immunity. We describe recent observations with regard to functional exhaustion of iNKT and MAIT cells in MM pathology and discuss the potential application of checkpoint inhibition as an attractive target for prolonged activation of these immunomodulatory T cells in the treatment of MM.

Towards Molecular Profiling in Multiple Myeloma: A Literature Review and Early Indications of Its Efficacy for Informing Treatment Strategies

Multiple myeloma (MM), the second most common hematologic malignancy, is characterized by the clonal expansion of plasma cells. Despite dramatic improvements in patients′ survival over the past decade due to advances in therapy exploiting novel molecular targets (immunomodulatory drugs, proteasome inhibitors and monoclonal antibodies), the treatment of relapsed and refractory disease remains challenging. Recent studies confirmed complex, dynamic, and heterogeneous genomic alterations without unifying gene mutations in MM patients. In the current review, we survey recent therapeutic strategies, as well as molecular profiling data on MM, with emphasis on relapsed and refractory cases. A critical appraisal of novel findings and of their potential therapeutic implications will be discussed in detail, along with the author’s own experiences/views.

Oncolytic Viruses for Multiple Myeloma Therapy

Although recent treatment advances have improved outcomes for patients with multiple myeloma (MM), the disease frequently becomes refractory to current therapies. MM thus remains incurable for most patients and new therapies are urgently needed. Oncolytic viruses are a promising new class of therapeutics that provide tumor-targeted therapy by specifically infecting and replicating within cancerous cells. Oncolytic therapy yields results from both direct killing of malignant cells and induction of an anti-tumor immune response. In this review, we will describe oncolytic viruses that are being tested for MM therapy with a focus on those agents that have advanced into clinical trials.

Bone marrow-derived mesenchymal stem cells promote cell proliferation of multiple myeloma through inhibiting T cell immune responses via PD-1/PD-L1 pathway

OBJECTIVES

This study aims to explore the effect of bone marrow mesenchymal stem cells (BMSCs) on multiple myeloma (MM) development and the underlying mechanism.

MATERIALS AND METHODS

BMSCs from C57BL/6 J mice were isolated and the third passage was used for subsequent experiments. Additionally, a series of in vitro transwell coculture assays were performed to explore the effects of BMSCs on the proliferation of MM cells 5TGM1 and CD4+ T cells. Furthermore, a 5TGM1-induced MM mice model was established. Moreover, PD-L1 shRNA was transfected into BMSCs to investigate whether PD-1/PD-L1 pathway involved in BMSCs-mediated regulation of T cells and MM growth.

RESULTS

Data revealed that BMSCs significantly promoted 5TGM1 proliferation in a dose-dependent manner. Furthermore, BMSCs administration exerted stimulatory effects on MM development in terms of shortening the mouse survival rate, promoting tumor growth, and enhancing inflammatory infiltration in the MM model mice. Moreover, BMSCs decreased the percentage of Th1 and Th17 cells, whereas increased that of Th2 and Treg cells. Their corresponding cytokines of these T cell subsets showed similar alteration in the presence of BMSCs. Additionally, BMSCs significantly suppressed CD4+ T cell proliferation. We also found that PD-L1 shRNA inhibited 5TGM1 proliferation likely through activation of CD4+ T cells. Further in vivo experiments confirmed that PD-L1 inhibition attenuated BMSCs-induced MM growth, inflammation infiltration and imbalance of Th1/Th2 and Th17/Treg.

CONCLUSION

In summary, our findings demonstrated that BMSCs promoted cell proliferation of MM through inhibiting T cell immune responses via PD-1/PD-L1 pathway.

Modulating PD-L1 expression in multiple myeloma: an alternative strategy to target the PD-1/PD-L1 pathway

Even with recent advances in therapy regimen, multiple myeloma patients commonly develop drug resistance and relapse. The relevance of targeting the PD-1/PD-L1 axis has been demonstrated in pre-clinical models. Monotherapy with PD-1 inhibitors produced disappointing results, but combinations with other drugs used in the treatment of multiple myeloma seemed promising, and clinical trials are ongoing. However, there have recently been concerns about the safety of PD-1 and PD-L1 inhibitors combined with immunomodulators in the treatment of multiple myeloma, and several trials have been suspended. There is therefore a need for alternative combinations of drugs or different approaches to target this pathway. Protein expression of PD-L1 on cancer cells, including in multiple myeloma, has been associated with intrinsic aggressive features independent of immune evasion mechanisms, thereby providing a rationale for the adoption of new strategies directly targeting PD-L1 protein expression. Drugs modulating the transcriptional and post-transcriptional regulation of PD-L1 could represent new therapeutic strategies for the treatment of multiple myeloma, help potentiate the action of other drugs or be combined to PD-1/PD-L1 inhibitors in order to avoid the potentially problematic combination with immunomodulators. This review will focus on the pathophysiology of PD-L1 expression in multiple myeloma and drugs that have been shown to modulate this expression.

Venetoclax: A new wave in hematooncology

Inhibitors of antiapoptotic proteins of the BCL2 family can successfully restart the deregulated process of apoptosis in malignant cells. Whereas nonselective agents have been limited by their affinity to different BCL2 members, thus inducing excessive toxicity, the highly selective BCL2 inhibitor venetoclax (ABT-199, Venclexta™) has an acceptable safety profile. To date, it has been approved in monotherapy for the treatment of relapsed or refractory chronic lymphocytic leukemia (CLL) with 17p deletion. Extension of indications can be expected in monotherapy and in combination regimens. Sensitivity to venetoclax is not common in lymphomas, but promising outcomes have been achieved in the mantle cell lymphoma group. Venetoclax is also active in multiple myeloma patients, especially in those with translocation t(11;14), even if high-risk features such as del17p are also present. Surprisingly, positive results are being obtained in elderly acute myeloid leukemia patients, in whom inhibition of BCL2 is able to substantially increase the efficacy of low-dose cytarabine or hypomethylating agents. Here, we provide a summary of available results from clinical trials and describe a specific mechanism of action that stands behind the efficacy of venetoclax in hematological malignancies.

The bone-marrow niche in MDS and MGUS: implications for AML and MM

Several haematological malignancies, including multiple myeloma (MM) and acute myeloid leukaemia (AML), have well-defined precursor states that precede the development of overt cancer. MM is almost always preceded by monoclonal gammopathy of undetermined significance (MGUS), and at least a quarter of all patients with myelodysplastic syndromes (MDS) have disease that evolves into AML. In turn, MDS are frequently anteceded by clonal haematopoiesis of indeterminate potential (CHIP). The acquisition of additional genetic and epigenetic alterations over time clearly influences the increasingly unstable and aggressive behaviour of neoplastic haematopoietic clones; however, perturbations in the bone-marrow microenvironment are increasingly recognized to have key roles in initiating and supporting oncogenesis. In this Review, we focus on the concept that the haematopoietic neoplasia-microenvironment relationship is an intimate rapport between two partners, provide an overview of the evidence supporting a role for the bone-marrow niche in promoting neoplasia, and discuss the potential for niche-specific therapeutic targets.

Oncolytic virotherapy as an immunotherapeutic strategy for multiple myeloma

Multiple Myeloma (MM), a clonal malignancy of antibody-producing plasma cells, is the second most common hematologic malignancy and results in significant patient morbidity and mortality. The high degree of immune dysregulation in MM, including T cell imbalances and up-regulation of immunosuppressive checkpoint proteins and myeloid derived suppressor cells, allows this malignancy to escape from host immune control. Despite advances in the therapeutic landscape of MM over the last decade, including the introduction of immunomodulatory drugs, the prognosis for this disease is poor, with less than 50% of patients surviving 5 years. Thus, novel treatment strategies are required. Oncolytic viruses (OV) are a promising new class of therapeutics that rely on tumour specific oncolysis and the generation of a potent adaptive anti-tumour immune response for efficacy. To date, a number of OV have shown efficacy in pre-clinical studies of MM with three reaching early phase clinical trials. OVs represent a rational therapeutic strategy for MM based on (1) their tumour tropism, (2) their ability to potentiate anti-tumour immunity and (3) their ability to be rationally combined with other immunotherapeutic agents to achieve a more robust clinical response.

Trial watch: DNA-based vaccines for oncological indications

DNA-based vaccination is a promising approach to cancer immunotherapy. DNA-based vaccines specific for tumor-associated antigens (TAAs) are indeed relatively simple to produce, cost-efficient and well tolerated. However, the clinical efficacy of DNA-based vaccines for cancer therapy is considerably limited by central and peripheral tolerance. During the past decade, considerable efforts have been devoted to the development and characterization of novel DNA-based vaccines that would circumvent this obstacle. In this setting, particular attention has been dedicated to the route of administration, expression of modified TAAs, co-expression of immunostimulatory molecules, and co-delivery of immune checkpoint blockers. Here, we review preclinical and clinical progress on DNA-based vaccines for cancer therapy.

PD-1/PD-L1 inhibitors in haematological malignancies: update 2017

The introduction of PD-1/PD-L1 pathway inhibitors is an important landmark in solid oncology with unprecedented practice-changing activity in various types of solid tumours. Among haematological malignancies, PD-1/PD-L1 inhibitors have been successful, so far, only in the treatment of classical Hodgkin lymphoma, which typically exhibits an over-expression of PD-1 ligands (PD-L1, PD-L2) due to alterations in chromosome 9p24.1. Such positive outcomes led to the US Food and Drug Administration approval of nivolumab use in relapsed Hodgkin lymphoma in 2016 as the first haematological indication. Although the results in other lymphoid malignancies have not been so striking, blockade of the PD-1/PD-L1 axis has led to meaningful responses in other lymphoma types such as diffuse large B-cell lymphoma, follicular lymphoma or several T-cell lymphomas. Monotherapy with PD-1/PD-L1 inhibitors in chronic lymphocytic leukaemia and multiple myeloma has been unsatisfactory, suggesting that a combinational approach with other synergistic drugs is needed. In the case of multiple myeloma, immunomodulatory agents together with corticosteroids represent the most promising combinations. Among myeloid malignancies, the anti-PD-1 monoclonal antibodies are examined dominantly in acute myeloid leukaemia and myelodysplastic syndromes in combination with potentially synergistic hypomethylating drugs such as 5-azacitidine, resulting in promising outcomes that warrant further investigation. We have described all available clinical results of PD-1/PD-L1 inhibitors in haematological malignancies and discussed related toxicities, as well as highlighted crucial preclinical studies in this review.

Current applications of multiparameter flow cytometry in plasma cell disorders

Multiparameter flow cytometry (MFC) has become standard in the management of patients with plasma cell (PC) dyscrasias, and could be considered mandatory in specific areas of routine clinical practice. It plays a significant role during the differential diagnostic work-up because of its fast and conclusive readout of PC clonality, and simultaneously provides prognostic information in most monoclonal gammopathies. Recent advances in the treatment and outcomes of multiple myeloma led to the implementation of new response criteria, including minimal residual disease (MRD) status as one of the most relevant clinical endpoints with the potential to act as surrogate for survival. Recent technical progress led to the development of next-generation flow (NGF) cytometry that represents a validated, highly sensitive, cost-effective and widely available technique for standardized MRD evaluation, which also could be used for the detection of circulating tumor cells. Here we review current applications of MFC and NGF in most PC disorders including the less frequent solitary plasmocytoma, light-chain amyloidosis or Waldenström macroglobulinemia.

Trial Watch: Adoptively transferred cells for anticancer immunotherapy

Immunotherapies aimed at strengthening immune effector responses against malignant cells are growing at exponential rates. Alongside, the impressive benefits obtained by patients with advanced melanoma who received adoptively transferred tumor-infiltrating lymphocytes (TILs) have encouraged the scientific community to pursue adoptive cell transfer (ACT)-based immunotherapy. ACT involves autologous or allogenic effector lymphocytes that are generally obtained from the peripheral blood or resected tumors, expanded and activated ex vivo, and administered to lymphodepleted patients. ACT may be optionally associated with chemo- and/or immunotherapeutics, with the overall aim of enhancing the proliferation, persistence and functionality of infused cells, as well as to ensure their evolution in an immunological permissive local and systemic microenvironment. In addition, isolated lymphocytes can be genetically engineered to endow them with the ability to target a specific tumor-associated antigen (TAA), to increase their lifespan, and/or to reduce their potential toxicity. The infusion of chimeric antigen receptor (CAR)-expressing cytotoxic T lymphocytes redirected against CD19 has shown promising clinical efficacy in patients with B-cell malignancies. Accordingly, the US Food and Drug Administration (FDA) has recently granted 'breakthrough therapy' designation to a CAR-based T-cell therapy (CTL019) for patients with B-cell malignancies. Considerable efforts are now being devoted to the development of efficient ACT-based immunotherapies for non-hematological neoplasms. In this Trial Watch, we summarize recent clinical advances on the use of ACT for oncological indications.