Bone Marrow Mesenchymal Stromal Cells in Multiple Myeloma: Their Role as Active Contributors to Myeloma Progression

Multiple myeloma (MM) is a hematological malignancy of plasma cells that proliferate and accumulate within the bone marrow (BM). Work from many groups has made evident that the complex microenvironment of the BM plays a crucial role in myeloma progression and response to therapeutic agents. Within the cellular components of the BM, we will specifically focus on mesenchymal stromal cells (MSCs), which are known to interact with myeloma cells and the other components of the BM through cell to cell, soluble factors and, as more recently evidenced, through extracellular vesicles. Multiple structural and functional abnormalities have been found when characterizing MSCs derived from myeloma patients (MM-MSCs) and comparing them to those from healthy donors (HD-MSCs). Other studies have identified differences in genomic, mRNA, microRNA, histone modification, and DNA methylation profiles. We discuss these distinctive features shaping MM-MSCs and propose a model for the transition from HD-MSCs to MM-MSCs as a consequence of the interaction with myeloma cells. Finally, we review the contribution of MM-MSCs to several aspects of myeloma pathology, specifically to myeloma growth and survival, drug resistance, dissemination and homing, myeloma bone disease, and the induction of a pro-inflammatory and immunosuppressive microenvironment.Funding: This study was funded by the Instituto de Salud Carlos III-FIS and co-financed by FEDER (PI19/01384 and PI18/01600); by the AECC (PROYE20047GUTI); the Network Center of Regenerative Medicine and Cellular Therapy of Castilla y León; and by the Gerencia Regional de Salud, Junta de Castilla y León (GRS 2066/A/19). P.M. (Patricia Maiso) was supported by a Miguel Servet fellowship from the ISCIII-FIS (CPII19/00028) co-financed by the European Social Fund; P.M. (Pedro Mogollón) is supported by a grant from IBSAL

Biological Background of Resistance to Current Standards of Care in Multiple Myeloma

A high priority problem in multiple myeloma (MM) management is the development of resistance to administered therapies, with most myeloma patients facing successively shorter periods of response and relapse. Herewith, we review the current knowledge on the mechanisms of resistance to the standard backbones in MM treatment: proteasome inhibitors (PIs), immunomodulatory agents (IMiDs), and monoclonal antibodies (mAbs). In some cases, strategies to overcome resistance have been discerned, and an effort should be made to evaluate whether resensitization to these agents is feasible in the clinical setting. Additionally, at a time in which we are moving towards precision medicine in MM, it is equally important to identify reliable and accurate biomarkers of sensitivity/refractoriness to these main therapeutic agents with the goal of having more efficacious treatments and, if possible, prevent the development of relapse.Funding: E.M.O. was supported by an Inplant grant fromIDIVALand TP by a grant fromAECC(INVES18043PAÍN). E.M.A. and A.D.-T. received a grant from the Regional Council from Castilla y León, and P.M. from the Institute for Biomedical Research from Salamanca. This work was supported by funding from Spanish FIS (PI15/00067, PI15/02156 and PI18/01600) and FEDER, AECC (GCB120981SAN), Ramón Areces Foundation (FRA16/003); the Regional Council from Castilla y León (GRS 1604/A/17, GRS 1880/A/18 and Centro en Red de Medicina Regenerativa y Terapia Celular), and the Institute for Biomedical Research from Salamanca (IBY17/00008)

Brave new world: expanding home care in stem cell transplantation and advanced therapies with new technologies

Hematopoietic stem cell transplantation and cell therapies like CAR-T are costly, complex therapeutic procedures. Outpatient models, including at-home transplantation, have been developed, resulting in similar survival results, reduced costs, and increased patient satisfaction. The complexity and safety of the process can be addressed with various emerging technologies (artificial intelligence, wearable sensors, point-of-care analytical devices, drones, virtual assistants) that allow continuous patient monitoring and improved decision-making processes. Patients, caregivers, and staff can also benefit from improved training with simulation or virtual reality. However, many technical, operational, and above all, ethical concerns need to be addressed. Finally, outpatient or at-home hematopoietic transplantation or CAR-T therapy creates a different, integrated operative system that must be planned, designed, and carefully adapted to the patient's characteristics and distance from the hospital. Patients, clinicians, and their clinical environments can benefit from technically improved at-home transplantation.Funding: The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article. Acknowledgments: The authors thank Jonathan McFarland for his invaluable help with the English version of the manuscript

The effect of the proteasome inhibitor bortezomib on acute myeloid leukemia cells and drug resistance associated with the CD34+ immature phenotype

[Background]: Proteasome inhibition represents a promising novel anticancer therapy, and bortezomib is a highly selective reversible inhibitor of the proteasome complex. Acute myeloid leukemia (AML) is an immnunophenotypically heterogeneous group of diseases, with CD34+ cases being associated with drug resistance and poor outcome. We investigated the effects of bortezomib on the growth and survival of AML cells. [Design and Methods]: We studied the in vitro activity and mechanism of action of bortezomib on both cell lines and fresh cells from 28 AML patients including CD34+ and CD34- cases. [Results]: Bortezomib showed potent anti-AML activity (IC50 < 50 nM), which was greater than that of conventional agents (doxorubicin, cytarabine and fludarabine). Moreover, synergistic effects were observed when bortezomib was adminstered in combination with doxorubicin and cytarabine. Mechanistically, bortezomib induced accumulation of cells in the G2/M phase, with up-regulation of p27, together with cell death through an increase in the mitochondrial outer membrane permeability involving caspase-dependent and -independent pathways. The apoptotic activity of bortezomib on fresh CD34 + blast cells from patients was similar to that observed on CD34 - blast cells. Importantly, bortezomib was significantly more active than doxorubicin in the immature CD34+ cells, while there were no differences in its action on CD34- cells. [Conclusions]: Bortezomib induces apoptosis in acute myeloid leukemia cells in vitro. Whether this drug might be useful in the treatment of patients with acute myeloid leukemia can be established only in ad hoc clinical trials. ©2008 Ferrata Storti Foundation.We thank Johnson and Johnson Pharmaceutical Research and Development (JJPRD).Peer Reviewe

The epoxyketone-based proteasome inhibitors carfilzomib and orally bioavailable oprozomib have anti-resorptive and bone-anabolic activity in addition to anti-myeloma effects

PMCID: PMC3771507.-- et al.Proteasome inhibitors (PIs), namely bortezomib, have become a cornerstone therapy for multiple myeloma (MM), potently reducing tumor burden and inhibiting pathologic bone destruction. In clinical trials, carfilzomib, a next generation epoxyketone-based irreversible PI, has exhibited potent anti-myeloma efficacy and decreased side effects compared with bortezomib. Carfilzomib and its orally bioavailable analog oprozomib, effectively decreased MM cell viability following continual or transient treatment mimicking in vivo pharmacokinetics. Interactions between myeloma cells and the bone marrow (BM) microenvironment augment the number and activity of bone-resorbing osteoclasts (OCs) while inhibiting bone-forming osteoblasts (OBs), resulting in increased tumor growth and osteolytic lesions. At clinically relevant concentrations, carfilzomib and oprozomib directly inhibited OC formation and bone resorption in vitro, while enhancing osteogenic differentiation and matrix mineralization. Accordingly, carfilzomib and oprozomib increased trabecular bone volume, decreased bone resorption and enhanced bone formation in non-tumor bearing mice. Finally, in mouse models of disseminated MM, the epoxyketone-based PIs decreased murine 5TGM1 and human RPMI-8226 tumor burden and prevented bone loss. These data demonstrate that, in addition to anti-myeloma properties, carfilzomib and oprozomib effectively shift the bone microenvironment from a catabolic to an anabolic state and, similar to bortezomib, may decrease skeletal complications of MM.This research was supported by grants from the National Institutes of Health (T32CA113275:MAH; P01CA100730:KNW; P50CA94056:DP-W), the St Louis Men’s Group Against Cancer (KNW), the Holway Myeloma Fund (KNW), the Spanish MICINN-ISCIII (PI081825), the Fundación de Investigación Médica Mutua Madrileña (AP27262008), the Centro en Red de Medicina Regenerativa y Terapia Celular de Castilla y León, the Spanish Myeloma Network Program (RD06/0020/0006 and RD06/0020/0041) and Spanish FIS (PS09/01897).Peer Reviewe

Predicting long-term disease control in transplant-ineligible patients with multiple myeloma: impact of an MGUS-like signature

Disease control; Multiple myeloma; BiomarkersControl de la malaltia; Mieloma múltiple; BiomarcadorsControl de la enfermedad; Mieloma múltiple; BiomarcadoresDisease control at 5 years would be a desirable endpoint for elderly multiple myeloma (MM) patients, but biomarkers predicting this are not defined. Therefore, to gain further insights in this endpoint, a population of 498 newly diagnosed transplant-ineligible patients enrolled in two Spanish trials (GEM2005MAS65 and GEM2010MAS65), has been analyzed. Among the 435 patients included in this post-hoc study, 18.6% remained alive and progression free after 5 years of treatment initiation. In these patients, overall survival (OS) rate at 10 years was 60.8% as compared with 11.8% for those progressing within the first 5 years. Hemoglobin (Hb) ≥ 12 g/dl (OR 2.74, p = 0.001) and MGUS-like profile (OR 4.18, p = 0.005) were the two baseline variables associated with long-term disease-free survival. Upon including depth of response (and MRD), Hb ≥ 12 g/dl (OR 2.27) and MGUS-like signature (OR 7.48) retained their predictive value along with MRD negativity (OR 5.18). This study shows that despite the use of novel agents, the probability of disease control at 5 years is still restricted to a small fraction (18.6%) of elderly MM patients. Since this endpoint is associated with higher rates of OS, this study provides important information about diagnostic and post-treatment biomarkers helpful in predicting the likelihood of disease control at 5 years

Brave new world: expanding home care in stem cell transplantation and advanced therapies with new technologies

Hematopoietic stem cell transplantation and cell therapies like CAR-T are costly, complex therapeutic procedures. Outpatient models, including at-home transplantation, have been developed, resulting in similar survival results, reduced costs, and increased patient satisfaction. The complexity and safety of the process can be addressed with various emerging technologies (artificial intelligence, wearable sensors, point-of-care analytical devices, drones, virtual assistants) that allow continuous patient monitoring and improved decision-making processes. Patients, caregivers, and staff can also benefit from improved training with simulation or virtual reality. However, many technical, operational, and above all, ethical concerns need to be addressed. Finally, outpatient or at-home hematopoietic transplantation or CAR-T therapy creates a different, integrated operative system that must be planned, designed, and carefully adapted to the patient’s characteristics and distance from the hospital. Patients, clinicians, and their clinical environments can benefit from technically improved at-home transplantation

Restoration of microRNA-214 expression reduces growth of myeloma cells through positive regulation of P53 and inhibition of DNA replication

This is an open-access paper.-- et al.MicroRNA have been demonstrated to be deregulated in multiple myeloma. We have previously reported that miR-214 is down-regulated in multiple myeloma compared to in normal plasma cells. The functional role of miR- 214 in myeloma pathogenesis was explored by transfecting myeloma cell lines with synthetic microRNA followed by gene expression profiling. Putative miR-214 targets were validated by luciferase reporter assay. Ectopic expression of miR-214 reduced cell growth and induced apoptosis of myeloma cells. In order to identify the potential direct target genes of miR-214 which could be involved in the biological pathways regulated by this microRNA, gene expression profiling of the H929 myeloma cell line transfected with precursor miR-214 was carried out. Functional analysis revealed significant enrichment for DNA replication, cell cycle phase and DNA binding. miR- 214 directly down-regulated the expression of PSMD10, which encodes the oncoprotein gankyrin, and ASF1B, a histone chaperone required for DNA replication, by binding to their 3'-untranslated regions. In addition, gankyrin inhibition induced an increase of P53mRNA levels and subsequent up-regulation of CDKN1A (p21Waf1/Cip1) and BAX transcripts, which are direct transcriptional targets of p53. In conclusion, MiR-214 functions as a tumor suppressor in myeloma by positive regulation of p53 and inhibition of DNA replication.This work was partially supported by the Spanish FIS (PI080568 and PS0901897), the >Gerencia Regional de Salud, Junta de Castilla y León> (GRS202/A08 and GRS 702/A/11), and the Spanish Myeloma Network Program (RD06/0020/0006). MES is supported by the Ministerio de Sanidad y Consumo (CA08/00212).Peer Reviewe

Zalypsis has in vitro activity in acute myeloid blasts and leukemic progenitor cells through the induction of a DNA damage response.

Background: Although the majority of patients with acute myeloid leukemia initially respond to conventional chemotherapy, relapse is still the leading cause of death, probably because of the presence of leukemic stem cells that are insensitive to current therapies. We investigated the antileukemic activity and mechanism of action of zalypsis, a novel alkaloid of marine origin. Design and methods: The activity of zalypsis was studied in four acute myeloid leukemia cell lines and in freshly isolated blasts taken from patients with acute myeloid leukemia before they started therapy. Zalypsis-induced apoptosis of both malignant and normal cells was measured using flow cytometry techniques. Gene expression profiling and western blot studies were performed to assess the mechanism of action of the alkaloid. Results: Zalypsis showed a very potent antileukemic activity in all the cell lines tested and potentiated the effect of conventional antileukemic drugs such as cytarabine, fludarabine and daunorubicin. Interestingly, zalypsis showed remarkable ex vivo potency, including activity against the most immature blast cells (CD34(+) CD38(-) Lin(-)) which include leukemic stem cells. Zalypsis-induced apoptosis was the result of an important deregulation of genes involved in the recognition of double-strand DNA breaks, such as Fanconi anemia genes and BRCA1, but also genes implicated in the repair of double-strand DNA breaks, such as RAD51 and RAD54. These gene findings were confirmed by an increase in several proteins involved in the pathway (pCHK1, pCHK2 and pH2AX). Conclusions: The potent and selective antileukemic effect of zalypsis on DNA damage response mechanisms observed in acute myeloid leukemia cell lines and in patients' samples provides the rationale for the investigation of this compound in clinical trials.Funding: this work was supported by a grant from the Ministry of Science and Innovation of Spain (BFU2006-01813/BMC and RD06/0020/ 0041).The CIC receives support from the European Community through the regional development funding program (FEDER).This work was also supported by the ‘AcciónTransversal del Cáncer’ project, through an agreement between the Instituto de Salud Carlos III (ISCIII), the Spanish Ministry of Science and Innovation, and the Cancer Research Foundation of Salamanca University. Our group also receives support from the Junta de Castilla y Léon through ‘Ayudas destinadas a financiar programas de actividad investigadora a realizar por grupos de investigación de excelencia de Castilla y León’

Melflufen: A Peptide-Drug Conjugate for the Treatment of Multiple Myeloma

Despite the availability of new therapies that have led to improved outcomes for patients with multiple myeloma, most patients will eventually relapse. With triplet and even quadruplet combination therapies becoming standard in the first and second line, many patients will have few treatment options after second-line treatment. Melflufen (melphalan flufenamide) is a first-in-class peptide-drug conjugate (PDC) that targets aminopeptidases and rapidly releases alkylating agents into tumor cells. Once inside the tumor cells, melflufen is hydrolyzed by peptidases to release alkylator molecules, which become entrapped. Melflufen showed anti-myeloma activity in myeloma cells that were resistant to bortezomib and the alkylator melphalan. In early phase studies (O-12-M1 and HORIZON [OP-106]), melflufen plus dexamethasone has demonstrated encouraging clinical activity and a manageable safety profile in heavily pretreated patients with relapsed/refractory multiple myeloma, including those with triple-class refractory disease and extramedullary disease. The Phase III OCEAN study (OP-104) is further evaluating melflufen plus dexamethasone in patients with relapsed/refractory multiple myeloma. The safety profile of melflufen is characterized primarily by clinically manageable hematologic adverse events. Melflufen, with its novel mechanism of action, has the potential to provide clinically meaningful benefits to patients with relapsed/refractory multiple myeloma, including those with high unmet needs.The authors received medical editorial support for the development of this manuscript, which was funded by Oncopeptides AB