Citations

Abstract Multiple myeloma (MM) bone disease is a significant cause of morbidity but there is a paucity of data on the impact of malignant plasma cells on adjacent trabecular bone within the BM. Here, we characterize the proteome of trabecular bone tissue from BM biopsies of 56 patients with monoclonal gammopathy of undetermined significance (MGUS), smoldering (SMM), newly diagnosed (NDMM), relapsed MM (RMM), and normal controls. Proteins involved in extracellular matrix (ECM) formation and immunity pathways were decreased in SMM and active MM. Among the proteins most decreased were immunoglobulins, type IV collagen, and TIMP3, suggesting increased immunoparesis and decreased ECM remodelling within trabecular bone. Proteins most increased in SMM/MM were APP (enhances osteoclast activity), ENPP1 (enhances bone mineralization), and MZB1 (required for normal plasmablast differentiation). Pathway analyses showed that proteins involved in gamma -carboxylation, a pathway implicated in osteocalcin function, osteoblast differentiation, and normal hematopoiesis, were also overexpressed in SMM/MM. This study is the first comprehensive proteomic atlas of the BM bone proteome in dysproteinemias. We identify new key proteins and pathways for MM bone disease and potentially impaired hematopoiesis, and show for the first time that gamma -carboxylation pathways are increased in the bone tissue of SMM/MM.

Abstract Multiple myeloma (MM) is a clonal plasma cell (PC) cancer that is preceded by the benign conditions monoclonal gammopathy of undetermined significance (MGUS) and smoldering MM (SMM). While MGUS/SMM PCs are not proliferative, many of the oncogenes and chromosomal abnormalities in MM PCs are also present in MGUS/SMM. Since oncogenic stress is known to induce cellular senescence, we hypothesized that MGUS/SMM PCs may be in a senescent-like state. Our analysis of a published human dataset (GSE5900) revealed that compared to healthy PCs, MGUS/SMM PCs had significantly increased expression of senescence markers CDKN1A and GADD45A (FDR<0.05). Gene Set Enrichment Analysis (GSEA) showed significant enrichment in MGUS/SMM PCs of our customized senescence phenotyping gene sets (q<0.25). We next evaluated the KaLwRij MGUS mouse model. 10-mo-old female KaLwRij mice were treated with placebo or senolytics (dasatinib+quercetin, D+Q). D+Q treatment significantly reduced PCs compared to placebo, while restoring B cell number and functional gene expression. PCs isolated from D+Q-treated KaLwRij mice exhibited significant reductions in Myc and Il1b expression (p<0.05) versus placebo and a trend towards reduced Trp53 expression (p=0.13), supporting that senescent PCs are targeted by D+Q. Single-cell RNA-seq and single sample (ss)GSEA of 24-mo-old KaLwRij PCs revealed a PC subset enriched for the ‘Plasma Cell Senescence’ gene set, which included genes from our customized gene sets that were differentially expressed in the human PCs dataset GSE5900. Notably, PCs in this subset showed enrichment for ‘Inflammatory SASP’ (median: 15.26%) and ‘Interferon (IFN) SASP’ (39.36%) gene sets. The IFN-SASP is characteristic of late senescence, driven by the accumulation of transposable elements. In the GSE5900 dataset, we found significant enrichment of ‘IFN-SASP’ in SMM (q<0.25) but not MGUS PCs. Further, whole transcriptome RNA-sequencing showed that SMM PCs had increased expression of LINE1 retrotransposon L1HS in relation to normal PCs (FDR<0.1), but not MGUS (FDR=0.83) or MM (FDR=0.5) PCs. Immunostaining confirmed increased cytosolic DNA:RNA hybrids in SMM (median frequency of cells exceeding the intensity threshold = 33%) versus MGUS (16.4%), MM (4.4%), and healthy PCs (1.5%), which is consistent with cytosolic DNA-mediated activation of the IFN SASP in SMM PCs. When these same patients were redistributed according to disease progression, L1HS was higher in patients with progressing SMM and newly diagnosed MM (NDMM) (FDR<0.1) versus patients with stable MGUS (FDR=0.56) or advanced MM (FDR=0.38). Increased DNA:RNA staining was observed in progressing SMM PCs (median frequency = 41%), but the results for NDMM patients (4.4%) and advanced MM (3%) were comparable to healthy or stable patients (3.5%). These data demonstrate that MGUS and SMM PCs exhibit senescence features, suggest mechanisms that may contribute to MM tumorigenesis, and show that pharmacological ablation of senescent cells may prevent progression from MGUS/SMM to MM. Citation Format: Gabriel Alvares Borges, Angelo Jose Guilatco, Christine M. Hachfeld, Ming Ruan, Sonya Royzenblat, Ming Xu, Claire M. Edwards, Marta Diaz-delCastillo, Thomas L. Andersen, Taxiarchis Kourelis, Tamar Tchkonia, James L. Kirkland, Matthew T. Drake, Megan Weivoda. Pre-malignant plasma cells exhibit a senescence-like phenotype and accumulation of transposable elements [abstract]. In: Proceedings of the AACR Special Conference: Aging and Cancer; 2022 Nov 17-20; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_1):Abstract nr PR012.

Abstract Multiple myeloma (MM) is an incurable plasma cell cancer. Therapeutic advances have greatly improved patient survival; however, all patients are expected to relapse. New treatments are critically needed to overcome relapse and provide durable response. There is evidence that dormant MM cells exist in the bone marrow, where they exhibit reduced proliferative capacity and resistance to treatment. These cells are present over extended periods of time and may regain proliferative capacity to drive relapse. Tumor dormancy shares features with senescence, a state of stress-induced growth arrest. Chemotherapies, including those used in the treatment of MM, have been shown to cause therapy-induced senescence in a variety of tissues. Dormant MM cells have been shown to be maintained in their non-proliferative state by interactions with bone lining cells. Interestingly, matrix signaling has also been shown to protect against chemotherapy-induced apoptosis in an in vitro ovarian cancer organoid model. Taken together, this suggests that interaction of MM cells with the bone niche maintains growth arrest and survival. We hypothesize that therapy-induced senescence drives dormancy in MM cells that depends on interactions with the mesenchymal bone niche. GFP-expressing 5TGM1 mouse MM cells were treated with vehicle or melphalan for 48 hours and then cultured in the presence or absence of ex vivo mouse bone marrow stromal cells (BMSCs). Cells were maintained for 12 additional days to allow for the development of senescence after the initial stress response. Cells were imaged and quantified during media replacements to assess adherence/survival. Cells were then fixed and stained for nuclei, phospho-γH2AX, and telomeres by immunofluorescence/fluorescence in-situ hybridization (IF/FISH). Melphalan-treated 5TGM1 cells cultured with BMSCs were significantly growth arrested over 2 weeks compared to vehicle-treated cells. Co-culture with BMSCs significantly enhanced melphalan-treated 5TGM1 adherence compared to culture without BMSCs during media replacement. Of note, melphalan-treated 5TGM1 did not survive in the absence of BMSCs after a week in culture. Melphalan-treated 5TGM1 also exhibited significantly greater adherence with BMSCs than vehicle-treated cells. Melphalan-treated 5TGM1 were significantly larger than vehicle-treated cells and exhibited both heterochromatin foci and persistent DNA damage foci associated with telomeres, which are all markers of cellular senescence. Our findings suggest that interactions with BMSCs promote the survival of melphalan-treated MM tumor cells. The enhanced adherence of these cells also suggests that current methods for minimal residual disease assessment may be inadequate, as rare populations of MM cells adhered to the marrow stroma may not be captured by routine bone marrow aspiration. These cells exhibit features of therapy-induced senescence which may be key to MM dormancy. Thus, targeting senescence survival pathways via senolytic therapy may be a novel approach to eliminate dormant MM cells and prevent disease relapse. Citation Format: Angelo J. Guilatco, Gabriel Alvares Borges, Tamar Tchkonia, James L. Kirkland, Taxiarchis Kourelis, Matthew T. Drake, Megan Weivoda. Enhanced survival and adherence of melphalan-induced senescent-like dormant multiple myeloma cells co-cultured with bone marrow stromal cells [abstract]. In: Proceedings of the AACR Special Conference: Aging and Cancer; 2022 Nov 17-20; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_1):Abstract nr B023.

Abstract This abstract is being presented as a short talk in the scientific program. A full abstract is available in the Short Talks from Proffered Abstracts section (PR012) of the Conference Proceedings. Citation Format: Gabriel Alvares Borges, Angelo Jose Guilatco, Christine M. Hachfeld, Ming Ruan, Sonya Royzenblat, Ming Xu, Claire M. Edwards, Marta Diaz-delCastillo, Thomas L. Andersen, Taxiarchis Kourelis, Tamar Tchkonia, James L. Kirkland, Matthew T. Drake, Megan Weivoda. Pre-malignant plasma cells exhibit a senescence-like phenotype and accumulation of transposable elements [abstract]. In: Proceedings of the AACR Special Conference: Aging and Cancer; 2022 Nov 17-20; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_1):Abstract nr B020.

AbstractBackgroundIntegrating shared decision making between patients and physicians and incorporating their values and preferences in the development of clinical practice guidelines (CPGs) is of critical importance to optimize CPG implementation and treatment adherence. This applies to many debilitating diseases, including hypercalcemia of malignancy (HCM).ObjectiveEvaluate patient and physician values, preferences, and attitudes to better inform CPGs to treat HCM in adults.MethodsWe followed a mixed-methods approach. We conducted a systematic review using 5 databases to identify studies reporting on patient and physician values, costs and resources, feasibility, acceptability, and equity regarding HCM treatment. We also gathered data from different countries on the cost of multiple treatment modalities. We collected data on outcome prioritization from the CPG Working Group. Similarly, we collected data from patients with HCM regarding outcome prioritization and administered a questionnaire to evaluate their attitudes and perceptions toward treatment as well as treatment acceptability and feasibility.ResultsIn the systematic review, we included 2 cross-sectional surveys conducted on the same population of physicians who agreed that treating HCM alleviates symptoms and improves quality of life; however, harms and benefits should be thoroughly considered when deciding on the duration of treatment. We also included 2 studies on cost showing that intravenous (IV) bisphosphonate is more cost-effective than a combination of IV bisphosphonate and calcitonin and administration of IV zoledronic acid at home is more cost-effective than other IV bisphosphonates. The cost of zoledronic acid, denosumab, and cinacalcet varied widely among countries and types (brand vs generic). Both the CPG Working Group and patients with HCM agreed that the most important outcomes when deciding on treatment were survival and resolution of HCM, but there was some variability in the ratings for other outcomes.ConclusionUsing mixed methods, CPG developers can obtain meaningful information regarding evidence to decision criteria. In the case of HCM CPGs, this approach has provided the required contextual information and supported the development of evidence-based recommendations.

AbstractContextHypercalcemia is a common complication of malignancy that is associated with high morbidity and mortality.ObjectiveTo support development of the Endocrine Society Clinical Practice Guideline for the treatment of hypercalcemia of malignancy in adults.MethodsWe searched multiple databases for studies that addressed 8 clinical questions prioritized by a guideline panel from the Endocrine Society. Quantitative and qualitative synthesis was performed. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess certainty of evidence.ResultsWe reviewed 1949 citations, from which we included 21 studies. The risk of bias for most of the included studies was moderate. A higher proportion of patients who received bisphosphonate achieved resolution of hypercalcemia when compared to placebo. The incidence rate of adverse events was significantly higher in the bisphosphonate group. Comparing denosumab to bisphosphonate, there was no significant difference in the rate of patients who achieved resolution of hypercalcemia. Two-thirds of patients with refractory/recurrent hypercalcemia of malignancy who received denosumab following bisphosphonate therapy achieved resolution of hypercalcemia. Addition of calcitonin to bisphosphonate therapy did not affect the resolution of hypercalcemia, time to normocalcemia, or hypocalcemia. Only indirect evidence was available to address questions on the management of hypercalcemia in tumors associated with high calcitriol levels, refractory/recurrent hypercalcemia of malignancy following the use of bisphosphonates, and the use of calcimimetics in the treatment of hypercalcemia associated with parathyroid carcinoma. The certainty of the evidence to address all 8 clinical questions was low to very low.ConclusionThe evidence summarized in this systematic review addresses the benefits and harms of treatments of hypercalcemia of malignancy. Additional information about patients’ values and preferences, and other important decisional and contextual factors is needed to facilitate the development of clinical recommendations.

Abstract Background Hypercalcemia of malignancy (HCM) is the most common metabolic complication of malignancies, but its incidence may be declining due to potent chemotherapeutic agents. The high mortality associated with HCM has declined markedly due to the introduction of increasingly effective chemotherapeutic drugs. Despite the widespread availability of efficacious medications to treat HCM, evidence-based recommendations to manage this debilitating condition are lacking. Objective To develop guidelines for the treatment of adults with HCM. Methods A multidisciplinary panel of clinical experts, together with experts in systematic literature review, identified and prioritized 8 clinical questions related to the treatment of HCM in adult patients. The systematic reviews (SRs) queried electronic databases for studies relevant to the selected questions. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assess the certainty of evidence and make recommendations. An independent SR was conducted in parallel to assess patients' and physicians' values and preferences, costs, resources needed, acceptability, feasibility, equity, and other domains relevant to the Evidence-to-Decision framework as well as to enable judgements and recommendations. Results The panel recommends (strong recommendation) in adults with HCM treatment with denosumab (Dmab) or an intravenous (IV) bisphosphonate (BP). The following recommendations were based on low certainty of the evidence. The panel suggests (conditional recommendation) (1) in adults with HCM, the use of Dmab rather than an IV BP; (2) in adults with severe HCM, a combination of calcitonin and an IV BP or Dmab therapy as initial treatment; and (3) in adults with refractory/recurrent HCM despite treatment with BP, the use of Dmab. The panel suggests (conditional recommendation) the addition of an IV BP or Dmab in adult patients with hypercalcemia due to tumors associated with high calcitriol levels who are already receiving glucocorticoid therapy but continue to have severe or symptomatic HCM. The panel suggests (conditional recommendation) in adult patients with hypercalcemia due to parathyroid carcinoma, treatment with either a calcimimetic or an antiresorptive (IV BP or Dmab). The panel judges the treatments as probably accessible and feasible for most recommendations but noted variability in costs, resources required, and their impact on equity. Conclusions The panel's recommendations are based on currently available evidence considering the most important outcomes in HCM to patients and key stakeholders. Treatment of the primary malignancy is instrumental for controlling hypercalcemia and preventing its recurrence. The recommendations provide a framework for the medical management of adults with HCM and incorporate important decisional and contextual factors. The guidelines underscore current knowledge gaps that can be used to establish future research agendas.

Tumor-induced osteomalacia is a rare and often misdiagnosed condition that presents with progressively worsening unexplained chronic pain and proximal muscle weakness. The osteomalacia leads to multiple stress fractures which do not heal properly, leading to progressive disability. It is caused by chronic hypophosphatemia due to inappropriate urinary phosphate wasting. This is due to a typically benign mesenchymal tumor that over-secretes a phospaturic hormone. Neurologists need to appreciate the relevance of chronic hypophosphatemia in people with chronic unexplained pain, as timely diagnosis and treatment of tumour-induced osteomalacia can be curative.