Therapeutic Approach In Multiple Myeloma Research Articles

Effectiveness and safety of bortezomib-dexamethasone regimen in patients with multiple myeloma: A prospective observational study

Background: Bortezomib and dexamethasone (BD) regimen offers a promising therapeutic approach in multiple myeloma (MM) by inhibiting the proteolytic pathway of tumor cells. Aims and Objectives: This study aims to assess the safety profile and treatment outcomes of MM patients undergoing the BD regimen. Materials and Methods: This prospective observational study included MM patients who received BD regimen. Patients received bortezomib (1.3 mg/m2 intravenous) weekly for 4 weeks along with dexamethasone (40 mg orally) weekly for 4 weeks. Clinical assessments were performed after each cycle, and adverse drug reactions were graded according to National Cancer Institute criteria. Treatment outcomes were evaluated after the 4th cycle based on specific parameters. Results: Thirty-seven patients, with a mean age of 56.2 years, predominantly male (56.8%), were included. Common symptoms included bone pain, fatigue, weight loss, and appetite loss. Toxicities were mainly grade 1 and 2, with peripheral neuropathy (PN) being the most prevalent. The BD regimen exhibited a response rate of 65%, accompanied by significant improvements in bone marrow plasma cells, β2 microglobulin, immunoglobulin assay, and erythrocyte sedimentation rate. In addition, treatment improved performance status, in 51.4% of patients achieving scores above 90 on the Karnofsky scale. Conclusion: The BD regimen demonstrated notable efficacy and tolerability in MM treatment. However, it is associated with a higher risk of PN.

Gene Expression Profiling to Predict Prognostic Biomarkers for Relapse in Multiple Myeloma

Background: Multiple myeloma (MM), an incurable malignancy of plasma cells (PCs), is the second most common hematological cancer caused primarily by structural variations (chromosomal aberrations and somatic mutations). The majority of the patients acquired resistance against standard therapeutic approaches for MM and experienced relapse despite the continuous advances in MM therapies.Methods: We performed Differential Gene Expression (DGE), literature mining and SNV analysis of Next Generation Sequencing (NGS) data of Newly Diagnosed MM (NDMM) and Relapsed/Refractory MM (RRMM). The selected Differentially Expressed Genes (DEGs) were subjected to functional enrichment and pathway analysis. Immune cells infiltration analysis was also performed to estimate immune cells variations in the Tumor Microenvironment (TME) of RRMM. Result: CSF1R, VCAN, NRP1, COL22A1, BPI, BIRC5, MNX1, FAT1, ERG, TCL1A, AFF3 were selected after DGE, literature mining and SNV analysis. The functional enrichment of these DEGs showed significant enrichment for positive regulation of cell population proliferation, serene/threonine kinase activity, endothelial cell proliferation, cytokine binding, G protein activity and GDP binding, whereas KEGG pathway analysis revealed vital role of PI3K-Akt signaling pathway along with various cancer pathways. The immune cells infiltration analysis revealed the higher count of neutrophils and lesser level of T cells (CD8+) in TME of RRMM. Conclusion: Our study suggests that neutrophils play an important role in modulation of TME in RRMM. The selected DEGs have previously been identified in progression, drug resistance and relapse of various cancers. The role of these biomarkers in RRMM has not been explored yet. Therefore, neutrophils, selected DEGs and PI3K-Akt signaling pathway are potential targets to investigate in RRMM.Keywords: Multiple Myeloma; Relapse; Differential Expression; Immune Cell Infiltration; Literature Mining

Abstract 3345: PP1 phosphatase complex at the hub of the integrated stress response: A potential therapeutic target in multiple myeloma

Abstract Protein phosphatase-1 (PP1) is a class of eukaryotic enzyme that catalyzes more than half of the phosphoserine/threonine dephosphorylation reactions, and plays essential roles in cell division, glycogen metabolism and protein synthesis. The substrate specificity of PP1 holoenzyme complex is mediated by PP1-interacting proteins and its catalytic subunits. Of note, PPP1R15B/CReP and PPP1R15A/GADD34 are regulatory subunits of PP1 complex that regulates global protein synthesis and mRNA translation through eIF2α dephosphorylation. Notably, PPP1R15B is constitutively expressed, whereas the expression of PPP1R15A is stress-inducible. Previous studies showed that multiple myeloma (MM), a hematological malignancy arising from immunoglobulin-secreting plasma cells, is characterized by continual ER stress and high dependency on the unfolded protein response (UPR). The integrated stress response (ISR) activated by eIF2α phosphorylation is the fastest reaction pathway of the UPR; however, its functional role and therapeutic potential in MM remains largely unknown. In this study, we performed gene expression analysis and super-enhancer (SE) profiling in MM cell lines, primary patient samples, normal CD138+ plasma cells and memory B cells. we found that PPP1R15B is highly expressed in MM cells as compared to healthy controls, but did not observe significant upregulation of PPP1R15A in MM cells. In addition, higher expression of PPP1R15B predicted poor overall survival of MM patients, suggesting its clinical relevance in MM pathogenesis. Depletion of PPP1R15B significantly reduced cell viability, proliferation and induced G2/M phase cell cycle arrest. Gene Ontology analysis of downregulated genes in response to PPP1R15B knockdown indicates significant association with the UPR pathway. Immunoblot analysis showed activation of ER stress pro-apoptotic executors PUMA, NOXA, and cleavage of caspase-12 in PPP1R15B knockdown cells. Furthermore, we examined the therapeutic effects of eIF2α dephosphorylation inhibitors, Salubrinal and Raphin1, on MM cells. Raphin1 is a selective inhibitor of PPP1R15B that binds strongly to the PPP1R15B-PP1c complex, whereas Salubrinal inhibits both PPP1R15A-PP1c and PPP1R15B-PP1c complex. Our data showed that both Salubrinal and Raphin1 inhibited MM cell proliferation in a dose-dependent manner, while sparing normal plasma cells. MM cell lines with elevated PPP1R15B expression level were more sensitive to Salubrinal or Raphin1 than those with lower PPP1R15B level. Similar changes in the expression patterns of ISR-related genes were observed in response to eIF2α dephosphorylation inhibitors. Taken together, our study suggests that targeting PPP1R15B-PP1c complex or maintaining eIF2α hyperphosphorylation may serve as a new therapeutic approach in MM, which warrants further investigation. Citation Format: Sinan Xiong, Jianbiao Zhou, Tze King Tan, Sabrina Hui-Min Toh, Tae-Hoon Chung, Takaomi Sanda, Wee Joo Chng. PP1 phosphatase complex at the hub of the integrated stress response: A potential therapeutic target in multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3345.

Tumor integrin targeted theranostic iron oxide nanoparticles for delivery of caffeic acid phenethyl ester: preparation, characterization, and anti-myeloma activities.

Multiple myeloma (MM) is characterized by the accumulation of malignant plasma cells preferentially in the bone marrow. Currently, emerging chemotherapy drugs with improved biosafety profiles, such as immunomodulatory agents and protease inhibitors, have been used in clinics to treat MM in both initial therapy or maintenance therapy post autologous hematopoietic stem cell transplantation (ASCT). We previously discovered that caffeic acid phenethyl ester (CAPE), a water-insoluble natural compound, inhibited the growth of MM cells by inducing oxidative stress. As part of our continuous effort to pursue a less toxic yet more effective therapeutic approach for MM, the objective of this study is to investigate the potential of CAPE for in vivo applications by using magnetic resonance imaging (MRI)-capable superparamagnetic iron oxide nanoparticles (IONP) as carriers. Cyclo (Arg-Gly-Asp-D-Phe-Cys) (RGD) is conjugated to IONP (RGD-IONP/CAPE) to target the overexpressed αvβ3 integrin on MMcells for receptor-mediated internalization and intracellular delivery of CAPE. A stable loading of CAPE on IONP can be achieved with a loading efficiency of 48.7% ± 3.3% (wt%). The drug-release studies indicate RGD-IONP/CAPE is stable at physiological (pH 7.4) and basic pH (pH 9.5) and subject to release of CAPE at acidic pH (pH 5.5) mimicking the tumor and lysosomal condition. RGD-IONP/CAPE causes cytotoxicity specific to human MM RPMI8226, U266, and NCI-H929 cells, but not to normal peripheral blood mononuclear cells (PBMCs), with IC50s of 7.97 ± 1.39, 16.75 ± 1.62, and 24.38 ± 1.71μM after 72-h treatment, respectively. Apoptosis assays indicate RGD-IONP/CAPE induces apoptosis of RPMI8226 cells through a caspase-9 mediated intrinsic pathway, the same as applying CAPE alone. The apoptogenic effect of RGD-IONP/CAPE was also confirmed on the RPMI8226 cells co-cultured with human bone marrow stromal cells HS-5 in a Transwell model to mimic the MM microenvironment in the bone marrow. In conclusion, we demonstrate that water-insoluble CAPE can be loaded to RGD-IONP to greatly improve the biocompatibility and significantly inhibit the growth of MMcells in vitro through the induction of apoptosis. This study paves the way for investigating the MRI-trackable delivery of CAPE for MM treatment in animal models in the future.

Unveiling the Discrepancy in Multiple Myeloma Risk Classification between Clinical Practice and SKY92 Test and the Impact on Survival

Introduction:Despite the advancements in therapeutic approaches for multiple myeloma (MM), which have led to improve the survival rates, a subset of high-risk patients still faces limited benefits from current treatments. Therefore, it is crucial to accurately identify specific patient groups who would benefit from tailored therapies through risk stratification. In this study, we aim to assess the risk classification of patients based on conventional risk markers currently used in clinical practices and with the gene expression profiling (GEP)-based SKY92 risk classifier (SkylineDx, San Diego). This approach could provide further insights for optimizing risk-adapted treatment compared to the standard guidelines used in clinical practice. Methods: The PRospective Observational Multiple Myeloma Impact Study (PROMMIS; NCT02911571) trial, a prospective US multicenter study, enrolled a total of 251 newly diagnosed MM patients (NDMM). The patients underwent risk stratification using two distinct approaches. Firstly, physicians assessed their risk of progression at the time of diagnosis according to their routine practice guidelines. Then, the patients were classified into risk groups using the SKY92 molecular test. The analysis involved the processing of RNA extracted from CD138-positive plasma cells (≥80% purity), which were isolated through immunomagnetic separation. SKY92 test was carried out either at the enrolling institute or by sending samples to a central laboratory. For 221 patients, progression-free survival (PFS) and overall survival (OS) data were available, with measurements taken from date of diagnosis; the median follow-up period was 38 months. Survival analysis was performed utilizing Cox proportional hazards model. Results: Based on conventional risk classification, 123 (49%) NDMM were classified as standard-risk and 128 (51%) patients as high-risk. However, SKY92 yielded a noticeable difference in classification, with 179 (71%) patients being categorized as standard-risk and 72 (29%) patients as high-risk. In specific 23 standard-risk and 79 high-risk (n=102, 41%) patients accordingly with clinical practice assessment were classified differently by the SKY92 test. Standard-risk and high-risk groups identified by current clinical practice classification showed a significant difference in PFS (HR: 1.6, 95%CI 1.0-2.4, p=0.031), but not in OS (HR: 1.9, 95%CI 0.9-4.0, p=0.10). With SKY92 risk stratification, instead, a significant difference was observed between the two risk groups in both PFS (HR: 2.1, 95%CI 1.4-3.1, p<0.001) and OS (HR: 3.7, 95%CI 1.8-7.6, p<0.001); furthermore, the median PFS for standard-risk and high-risk patients was, respectively, 50 and 26 months. The median OS was not reached within the 60-month timeframe for both groups. For the n=221 MM patients with survival data, we observed that most patients classified as standard-risk based on clinical practice classification were also categorized as standard-risk according to SKY92 analysis (83 out of 105, 79%). However, among those initially identified as high-risk by conventional risk classification, 71 out of 116 (61%) patients exhibit no significant difference in PFS (HR: 1.1, 95%CI 0.6-1.8, p=0.8) and OS (HR: 0.6, 95%CI 0.2-1.9, p=0.4) when compared to standard-risk patients, as determined by both risk classification methods ( Figure 1). Conversely, only 22 out of 72 (30%) patients initially identified as high-risk by SKY92 and as standard-risk by clinical practice show no significance difference for PFS (HR: 1.1, 95%CI 0.5-2.4, p=0.8) and OS (HR: 0.9, 95%CI 0.2-4.1, p=0.9) compared with standard-risk patients determined by both tests. Forty-five patients identified as HR by both risk classification methods show highly significant differences for PSF (HR: 2.9, 95%CI 1.7-4.9, p<0.001) and OS (HR: 4.1, 95%CI 1.8-9.6, p<0.001) compare with standard-risk group. Conclusions: These findings based on prospective real-world clinical data, collected in a prospective US multicenter trial confirm the effectiveness of the GEP SKY92 on risk stratification both for PFS and OS. These results support the added value of integrating SKY92 into clinical practice for precise risk assessment of patients. Figure1: PFS and OS based on the combination of the clinical risk assessment (CRA) and the SKY92 risk.

The BCMA-Targeted Fourth-Generation CAR-T Cells Secreting CST6 Against Multiple Myeloma and Suppresses Osteolytic Lesions

651 Multiple Myeloma and Plasma Cell Dyscrasias: Basic and Translational Introduction: Multiple myeloma (MM) is characterized by osteolytic lesions, and our previous research has shown that cystatin E/M (CST6) effectively mitigates MM bone disease by inhibiting osteoclast differentiation. However, the therapeutic application of recombinant CST6 protein faces challenges due to its short serum half-life in mouse models, necessitating maintenance of constantly elevated CST6 concentrations for optimal efficacy. In this study, we explore the potential of utilizing fourth-generation B cell maturation antigen (BCMA)-specific chimeric antigen receptor (CAR)-T cell therapies to address this limitation. By leveraging the secretion capabilities of CST6, we engineered BCMA-CST6-CAR-T cells to precisely target nascent focal lesions. Our results demonstrate that these engineered CAR-T cells effectively target MM cells and concurrently suppress osteolytic lesions, presenting a promising approach for combating MM and its associated bone pathology. Methods: The BCMA-CST6-CAR vector comprises BCMA-scFv, a 4-1BB co-activation domain, and CD3ζ. To facilitate separate expression, a P2A self-cleaving peptide was introduced between CAR and CST6. CAR-T cells were co-cultured with MM1.S cells at a 5:1 ratio for 24 hours. To assess in vivo anti-tumor activity and anti-bone resorption of BCMA-CST6-CAR-T cells, we engrafted luciferase-expressing MM1.S cells into NSG mice. On day 7, mice with established MM received CAR-T cell infusions. At day 35, the mice were euthanized, and we analyzed serum CST6 concentrations using ELISA. Additionally, we collected mouse tibiae to perform μCT scans and TRAP staining to evaluate bone resorption. Results: The co-culturing of BCMA-CST6-CAR-T cells with MM1.S cells resulted in a remarkable 77.2% lysis of MM1.S cells after 24 hours, with no significant difference in killing observed between the BCMA-CAR-T and BCMA-CST6-CAR-T groups. However, T cell activation marker CD69 exhibited a significant increase in the BCMA-CST6-CAR-T group (70.9%) compared to the MOCK-CAR-T group (9.2%). In the MM-bearing mouse model, bioluminescence imaging revealed that BCMA-CST6-CAR-T cells exhibited excellent antitumor activity, leading to near-complete tumor clearance by day 21. Notably, both BCMA-CST6-CAR-T and BCMA-CAR-T cells showed similar effects in inhibiting tumor growth. The in vivo serum concentration of CST6 was significantly higher in the BCMA-CST6-CAR-T group (938.4 ng/ml) compared to the MOCK group (60.9 ng/ml) and BCMA-CAR-T group (64.2 ng/ml) (P < 0.001), highlighting the robust secretion of CST6 protein by BCMA-CST6-CAR-T cells. Moreover, μCT images of mouse tibiae demonstrated that BCMA-CST6-CAR-T cells effectively suppressed osteolytic lesions in MM-bearing mice. This finding was further corroborated by TRAP staining of mouse tibia sections, which showed a significant reduction in osteoclast numbers and the proportion of bone surface occupied by osteoclasts in the presence of BCMA-CST6-CAR-T cells. Conclusion: These results underscore the potent antitumor and anti-bone resorption effects of BCMA-CST6-CAR-T cells and their potential as a promising therapeutic approach for multiple myeloma.

Advanced practice nurse management in multiple myeloma treated with oral therapy

Therapeutic approaches in Multiple Myeloma (MM) have considerably changed over the last few years, with effective oral chemotherapy and continuous treatment. In this context, the objective of this study was to examine the circuitry of an advanced practitioner nurse (APN)-led intervention that provided supportive care for MM patients treated with oral chemotherapy. This population-based study was conducted at the hematology department-Institut de Cancérologie Lucien Neuwirth (ICLN, Saint-Priest-en-Jarez), from April 2017 to September 2020. A follow-up program was established with a specialized APN in oncology. All APN interventions were recorded, representing 1240 phone calls and 162consultations for 42MM patients. Eighty-two calls were referred to the physician with 45consultations triggered. Most of the calls were frequent within the few first months, with a high request for information and reassurance, especially for treatment-naive or relapsed patients. In our study, the APN was able to manage multiple side effects through care organization (i.e., hospitalizations, transfusions) and a careful coordination between the primary care team and the hospital. In order to respond to the high need for care pathway and safety improvement, especially in elderly population, we have initiated an original follow-up by an APN for MM patients treated with oral chemotherapy. While the role of APN has become prominent in the oncology field in recent years, its holistic approach has to be emphasized in further studies to bring a comprehensive perspective to health care coordination in the future.

Zinc Oxide Nanoparticles Trigger Autophagy in the Human Multiple Myeloma Cell Line RPMI8226: an In Vitro Study.

Multiple myeloma (MM) is a malignant clonal proliferative plasma cell tumor. Zinc oxide nanoparticles (ZnO NPs) are used for antibacterial and antitumor applications in the biomedical field. This study investigated the autophagy-induced effects of ZnO NPs on the MM cell line RPMI8226 and the underlying mechanism. After RPMI8226 cells were exposed to various concentrations of ZnO NPs, the cell survival rate, morphological changes, lactate dehydrogenase (LDH) levels, cell cycle arrest, and autophagic vacuoles were monitored. Moreover, we investigated the expression of Beclin 1 (Becn1), autophagy-related gene 5 (Atg5), and Atg12 at the mRNA and protein levels, as well as the level of light chain 3 (LC3). The results showed that ZnO NPs could effectively inhibit the proliferation and promote the death of RPMI8226 cells in vitro in a dose- and time-dependent manner. ZnO NPs increased LDH levels, enhanced monodansylcadaverine (MDC) fluorescence intensity, and induced cell cycle arrest at the G2/M phases in RPMI8226 cells. Moreover, ZnO NPs significantly increased the expression of Becn1, Atg5, and Atg12 at the mRNA and protein levels and stimulated the production of LC3. We further validated the results using the autophagy inhibitor 3-methyladenine (3‑MA). Overall, we observed that ZnO NPs can trigger autophagy signaling in RPMI8226 cells, which may be a potential therapeutic approach for MM.

Andrographolide induced ferroptosis in multiple myeloma cells by regulating the P38/Nrf2/HO-1 pathway

Andrographis paniculata is used as a functional food in Asia. Andrographolide (Andro), a diterpene lactone isolated from Andrographis paniculata, has been reported to have potent anticancer activity. Multiple myeloma (MM), the second most common malignant tumor in hematology, is incurable. Ferroptosis, a type of cell death driven by iron-dependent lipid peroxidation, has shown potential in the treatment of various cancers. However, previous studies have not demonstrated whether Andro inhibits the development of MM via ferroptosis or any other mechanism. In the present study, we observed that Andro induced cell death, G0/G1 cell cycle arrest and evoked oxidative stress in MM cells. Interestingly, these phenomena were accompanied by increases in intracellular and mitochondrial Fe2+ and lipid peroxidation levels. Furthermore, treatment with ferroptosis inhibitors rescued Andro-induced cell death, which indicated that ferroptosis contributed to this phenomenon. Mechanistic examination showed that Andro may block the Nrf2/HO-1 signaling pathway by activating P38, thereby inducing ferroptosis. Moreover, inhibition of P38 expression rescued Andro-induced cell death, changes in the level of Nrf2 and HO-1 expression, Fe2+ and lipid peroxidation. Taken together, our findings suggest that Andro induces ferroptosis in MM cells via the P38/Nrf2/HO-1 pathway, providing a potential preventative and therapeutic approach for MM.

Abstract 1615: NMS-812, a novel potent PERK inhibitor that also inhibits GCN2, exhibits strong anti-tumor activity as single agent and in combination in preclinical models

Abstract PERK and GCN2 are eIF-2α serine-threonine kinases activated by endoplasmic reticulum (ER) stress and amino acid deprivation respectively. These kinases are key effectors of the unfolded protein response (UPR) and amino acid Response (AAR) branches of the integrated stress response (ISR). ISR downregulates protein synthesis while upregulating specific genes in response to various cellular stresses, thus allowing adaptation and survival. PERK and GCN2 cooperate to modulate survival under stress conditions in cancer cells, with GCN2 activation compensating when PERK is inhibited, therefore suggesting a certain degree of redundancy between the two. Multiple myeloma (MM) and other protein-secreting tumors are highly dependent on UPR for survival, due to their high protein load. Therefore, PERK inhibition represents a promising anticancer approach in these tumor types. Notably, in these contexts, dual PERK/GCN2 inhibition may be more effective than inhibiting the single kinase.NMS-03597812 is a novel, very potent, ATP-competitive PERK/GCN2 inhibitor, NMS-812 is preferentially active in vitro on multiple myeloma cell lines; activity has however been observed also on lymphoma and selected solid tumor cell lines, suggesting a broader but still specific role of PERK and GCN2 inhibition depending on cell context. In assays revealing the mechanism of action, as expected, a transient dose-dependent eIF2α pathway activation is observed, suggesting the attempt of GCN2 to compensate for PERK inhibition. However, at higher doses, NMS-812 strongly induces pathway downmodulation and apoptosis compared to prototype PERK selective inhibitors. NMS-812 treatment of a MM xenograft model significantly prolongs the median survival time as single agent and demonstrates synergistic activity with MM standard of care (SOC) agents. In lymphoma, NMS-812 shows activity both as single agent and in combination with SOC.NMS-812 shows a favorable in vitro ADME profile and good PK properties with oral bioavailability in preclinical species and an acceptable toxicity profile. NMS-812 is a novel dual, PERK/GCN2 inhibitor with potential for first-in-class, that validates dual PERK and GCN2 inhibition as a therapeutic approach for MM and other PERK/GCN2-dependent settings. Based on these promising results, a Ph1 study has been started in Multiple Myeloma with plans to expand to other malignancies in the near future. Citation Format: Claudia Perrera, Maurizio Pulici, Patrizia Banfi, Nilla Avanzi, Davide Carenzi, Daniele Casero, Antonella Ciavolella, Laura Gianellini, Fabio Gasparri, Grazia Saturno, Barbara Valsasina, Elena Ardini, Alessia Montagnoli, Arturo P. Galvani, Antonella Isacchi. NMS-812, a novel potent PERK inhibitor that also inhibits GCN2, exhibits strong anti-tumor activity as single agent and in combination in preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1615.

Unraveling the Role of Peroxisome Proliferator-Activated Receptor β/Δ (PPAR β/Δ) in Angiogenesis Associated with Multiple Myeloma.

Growing evidence suggests a role for peroxisome proliferator-activated receptor β/δ (PPAR β/δ) in the angiogenesis, growth, and metastasis of solid tumors, but little is known about its role in multiple myeloma (MM). Angiogenesis in the bone marrow (BM) is characteristic of disease transition from monoclonal gammopathy of undetermined significance (MGUS) to MM. We examined the expression and function of PPAR β/δ in endothelial cells (EC) from the BM of MGUS (MGEC) and MM (MMEC) patients and showed that PPAR β/δ was expressed at higher levels in MMEC than in MGEC and that the overexpression depended on myeloma plasma cells. The interaction between myeloma plasma cells and MMEC promoted the release of the PPAR β/δ ligand prostaglandin I2 (PGI2) by MMEC, leading to the activation of PPAR β/δ. We also demonstrated that PPAR β/δ was a strong stimulator of angiogenesis in vitro and that PPAR β/δ inhibition by a specific antagonist greatly impaired the angiogenic functions of MMEC. These findings define PGI2-PPAR β/δ signaling in EC as a potential target of anti-angiogenic therapy. They also sustain the use of PPAR β/δ inhibitors in association with conventional drugs as a new therapeutic approach in MM.

New concepts in multiple myeloma by returning to cytogenetics

Multiple myeloma (MM) is characterized by genomic instability, which causes multiple genetic and chromosomal alterations and leads to disease progression and therapeutic resistance. Overlapping mechanisms, including defective genome repair machinery such as the loss of TP53 activity, as well as chromosomal segregation error represented by the abnormality of mitotic checkpoint kinases such as BUB1, cell cycle dysregulation, and tumor environment, cause structural and numerical chromosomal abnormalities. Cytogenetic abnormalities are important prognostic factors, and they are also linked to the use of proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, and the BCL2 inhibitor venetoclax. We developed new diagnostic modalities for chromosomal analysis to improve the sensitivity and convenience of chromosomal diagnosis. The immunophenotyped-suspension-multiplex (ISM)-fluorescence in situ hybridization (FISH) can use imaging flow to examine three IGH-related chromosomal translocations at the same time. We also created a new FISH method called amplified FISH (amFISH) to detect microdeletion involving narrow chromosomal regions (approximately<100 kb), such as the microdeletions of 1p32 (CDKN2C) or of 14q32 (TRAF3), by using a fluorescent antibody to amplify the signals of small probes. Even in the era of clinical sequencing, these convenient modalities may hasten the cytogenetics-oriented therapeutic approach for MM.

Anti-BCMA-CAR NK Cells Expressing Soluble TRAIL: Promising Therapeutic Approach for Multiple Myeloma in Combination with Bortezomib and γ-Secretase Inhibitors

Anti-BCMA-CAR NK Cells Expressing Soluble TRAIL: Promising Therapeutic Approach for Multiple Myeloma in Combination with Bortezomib and γ-Secretase Inhibitors

PB1992: HISPANIC ETHNICITY AS A STRONG PREDICTOR OF POOR RESPONSE TO INDUCTION THERAPY AND ASCT IN TRANSPLANT ELIGIBLE MULTIPLE MYELOMA PATIENTS

Background: Attempts have been made to use machine learning analysis of multidimensional data to determine personalized therapeutic approaches in multiple myeloma. Outcomes of disparities in Hispanic multiple myeloma treatment have been attributed in part to inadequate access to novel therapies and autologous stem cell transplant (ASCT). We sought to utilize a machine learning approach to identify clinical and demographic features associated with patient responses to multiple myeloma induction therapy and ASCT Aims: We aimed to employ machine learning analysis in the identification of clinical and demographic characteristics associated with patients’ response to multiple myeloma induction therapy and ASCT Methods: A retrospective chart review of patients with a documented diagnosis of multiple myeloma seen at the University of Arizona Cancer Center between January 2017 and April 2021 was performed. RedCapp was utilized to organize demographic, clinical, laboratory, therapeutic, and outcome data. A patient’s best response (per the IMWG myeloma response criteria) following induction therapy prior to ASCT was classified into the following categories: progression of disease, less than PR (partial response), partial response (PR), very good partial response (VGPR), complete response (CR), and stringent complete response (sCR). This response was then compared to the response at 100 days post-transplant and labeled as ‘1’ if the response improved or ‘0’ if the response stayed the same or worsened. A clinical decision tree model was generated by recursive partitioning and minimizing cross-validation error, which outperformed other tested models (e.g elastic net and LASSO regression) in accuracy. Critical indices that best stratified patient’s response (1 vs 0) were then identified based on the tree model. Results: Of 112 patients reviewed, 48 were transplant-eligible and had complete data for analysis. Among available input features derived from RedCapp, (including demographic and clinical baseline factors and the choice of first induction regimen), ethnicity (Hispanic/non-Hispanic) was identified as the central node in the tree model that stratified patient responses. Among Hispanic patients (23% in this cohort), only 18% showed any improvement in their documented best response when comparing induction therapy and 100 days after transplant. In contrast, among non-Hispanic patients (77% in this cohort), 68% exhibited an improvement. Furthermore, serum creatinine (sCr) was identified as the key risk factor in non-Hispanic patients, with those having sCr ≥ 1.6 (mg/dL) showing a much smaller chance of improvement (17%) on day 100 post-transplant compared with patients with sCr < 1.6 (79%). Image:Summary/Conclusion: Utilizing a machine learning-enabled analysis of multidimensional data from 48 patients, we identified Hispanic ethnicity and renal dysfunction at the time of diagnosis (sCr ≥ 1.6) as key factors that may impact patient responses between the end of induction therapy and at 100 days post-transplant. Although limited to a single institution and a small sample size, these findings warrant further evaluation in larger patient cohorts, and raise important questions regarding the pathobiology and corresponding therapeutic strategies for multiple myeloma in Hispanic populations. This study further illustrates the utility of data-driven approaches such as machine learning to shed light on complex issues such as cancer care and related disparities as well as the pathobiology and therapy choice of the complex disease of multiple myeloma.

The PARP1 Inhibitor Niraparib Represses DNA Damage Repair and Synergizes with Temozolomide for Antimyeloma Effects

Purpose Poly(ADP-ribose) polymerase 1 (PARP1) is necessary for single-strand break (SSB) repair by sensing DNA breaks and facilitating DNA repair through poly ADP-ribosylation of several DNA-binding and repair proteins. Inhibition of PARP1 results in collapsed DNA replication fork and double-strand breaks (DSBs). Accumulation of DSBs goes beyond the capacity of DNA repair response, ultimately resulting in cell death. This work is aimed at assessing the synergistic effects of the DNA-damaging agent temozolomide (TMZ) and the PARP inhibitor niraparib (Nira) in human multiple myeloma (MM) cells. Materials and Methods MM RPMI8226 and NCI-H929 cells were administered TMZ and/or Nira for 48 hours. CCK-8 was utilized for cell viability assessment. Cell proliferation and apoptosis were detected flow-cytometrically. Immunofluorescence was performed for detecting γH2A.X expression. Soft-agar colony formation assay was applied to evaluate the antiproliferative effect. The amounts of related proteins were obtained by immunoblot. The combination index was calculated with the CompuSyn software. A human plasmacytoma xenograft model was established to assess the anti-MM effects in vivo. The anti-MM activities of TMZ and/or Nira were evaluated by H&E staining, IHC, and the TUNEL assay. Results The results demonstrated that cotreatment with TMZ and Nira promoted DNA damage, cell cycle arrest, and apoptotic death in cultured cells but also reduced MM xenograft growth in nude mice, yielding highly synergistic effects. Immunoblot revealed that TMZ and Nira cotreatment markedly increased the expression of p-ATM, p-CHK2, RAD51, and γH2A.X, indicating the suppression of DNA damage response (DDR) and elevated DSB accumulation. Conclusion Inhibition of PARP1 sensitizes genotoxic agents and represents an important therapeutic approach for MM. These findings provide preliminary evidence for combining PARP1 inhibitors with TMZ for MM treatment.

Targeting Chemokine Receptor CCR1 as a Potential Therapeutic Approach for Multiple Myeloma.

Multiple myeloma is an incurable plasma B-cell malignancy with 5-year survival rates approximately 10-30% lower than other hematologic cancers. Treatment options include combination chemotherapy followed by autologous stem cell transplantation. However, not all patients are eligible for autologous stem cell transplantation, and current pharmacological agents are limited in their ability to reduce tumor burden and extend multiple myeloma remission times. The “chemokine network” is comprised of chemokines and their cognate receptors, and is a critical component of the normal bone microenvironment as well as the tumor microenvironment of multiple myeloma. Antagonists targeting chemokine-receptor 1 (CCR1) may provide a novel approach for treating multiple myeloma. In vitro CCR1 antagonists display a high degree of specificity, and in some cases signaling bias. In vivo studies have shown they can reduce tumor burden, minimize osteolytic bone damage, deter metastasis, and limit disease progression in multiple myeloma models. While multiple CCR1 antagonists have entered the drug pipeline, none have entered clinical trials for treatment of multiple myeloma. This review will discuss whether current CCR1 antagonists are a viable treatment option for multiple myeloma, and studies aimed at identifying which CCR1 antagonist(s) are most appropriate for this disease.

Dual Chimeric Antigen Receptor Approach Combining Novel Tumor Targeting Strategies Circumvents Antigen Escape in Multiple Myeloma

Chimeric antigen receptor (CAR) T-cell therapy has proven highly effective in patients with hematological malignancies. However, resistance to CAR-T cell therapy arising from target protein shedding and other forms of antigen downregulation can lead to CAR-resistant disease relapse. Tumor escape may be successfully prevented through the simultaneous targeting of multiple tumor antigens. The ability to target multiple antigens with a single therapeutic modality offers the potential for anti-tumor responses, broader coverage of heterogeneous tumor populations, and the potential to prevent antigen escape, potentially inducing durable clinical remission. Multiple myeloma (MM) presents an ideal case to employ a dual-CAR approach, as BCMA-targeting cell therapies have shown impressive efficacy to date, but curative treatment remains elusive. Additionally, the oligoclonal nature of MM may contribute to antigen escape and clonal resistance. Here, we demonstrate the application of a unique dual-CAR approach simultaneously targeting two tumor associated antigens (TAA) for the treatment of MM. We further demonstrate the efficacy in an induced pluripotent stem cell (iPSC) platform, where a master engineered iPSC line is used as the starting material for mass production of off-the-shelf, dual-CAR immune effector cells.We selected B cell maturation antigen (BCMA), a well-defined TAA in MM, as the first antigen target. To develop the CAR-BCMA motif, we utilized our previously published high-affinity binding sequence shown to exhibit high selectivity to BCMA with enhanced recognition of low-BCMA expressing myeloma cells (Bluhm et al., Molec Ther 2018). As shown previously, the designed CAR-BCMA demonstrates potent and selective cellular cytotoxicity against MM (Figure 1a, left panel). BCMA has been observed to be actively cleaved from the surface of MM cells though, resulting in reduced efficacy and clinical relapse. To circumvent BCMA antigen escape, we developed a companion CAR targeting the pan-TAAs, MICA and MICB, which are expressed on MM plasma cells as well as monoclonal gammopathy of undetermined significance (MGUS) plasma cells. The CAR binding sequence targets the conserved α3 domain of MICA/MICB, which we have previously shown to inhibit MICA/B shedding and drive anti-tumor immunity (Andrade et al., Science 2018). The designed anti-MICA/B-α3 CAR exhibits selective targeting potential against an array of cancers, including the MM.1S cancer cell line (Figure 1a, right panel). To determine the suitability of co-targeting BCMA and MICA/B in MM, we surveyed surface expression patterns of BCMA and MICA/B antigens on a variety of MM cancer cell lines and observed a complimentary pattern of co-expression compatible with a dual-CAR to broaden targeting approach of malignant plasma cells (Figure 1b). Initial studies to evaluate the dual CAR approach in MM were performed by generating anti-BCMA and anti-MICA/B-α3 dual-CAR (MM dual-CAR) T-cells. MM dual-CAR T cells showed antigen-specific activation, degranulation and cytotoxicity against both antigens in an additive manner, consistent with the initial antibody staining on target cells and illustrating that co-targeting MICA/B and BCMA may increase the activity against MM (Figure 1c). Similar trends were observed in a series of cytotoxicity assays against several MM lines. Preliminary studies are ongoing in induced pluripotent stem cell (iPSC)-derived NK (iNK) cells expressing MM dual-CARs as a unique off-the-shelf cell therapy targeting both BCMA and MICA/B. Since MM dual-CAR iNK cells also express CD16, which mediates antibody-dependent cellular cytotoxicity, combination with therapeutic antibodies, such as anti-CD38 antibodies, can be deployed to target three TAAs for a complete therapeutic approach in MM. The data highlights the applicability of a multi-targeted approach in MM patients, whereby MM dual-CAR NK and/or T cells maintain responsiveness to malignant cells that shed or downregulate tumor antigens to evade treatment. [Display omitted] DisclosuresLee: Fate Therapeutics, Inc.: Current Employment. Wucherpfennig: Novartis: Research Funding; SQZ Biotech: Membership on an entity's Board of Directors or advisory committees; TScan Therapeutics: Membership on an entity's Board of Directors or advisory committees; Immunitas Therapeutics: Current holder of individual stocks in a privately-held company; Nextechinvest: Membership on an entity's Board of Directors or advisory committees; TCR2 Therapeutics: Membership on an entity's Board of Directors or advisory committees. Bjordahl: Fate Therapeutics: Current Employment. Valamehr: Fate Therapeutics, Inc.: Current Employment.

CN41 Advanced practice nurse management in multiple myeloma treated with lenalidomide dexamethasone: “A new challenge”?

Therapeutic approaches in Multiple Myeloma (MM) have considerably changed over the last few years, with an increase in effective oral chemotherapy and continuous treatment. In line with the 2014-2019 cancer plan and its goals of improving oral chemotherapy safety and coordination, an innovative follow-up protocol by advanced practice nurse (APN) has been implemented at the ICLN (Institut de Cancérologie de la Loire Lucien Neuwirth). While the role of APN is well defined in North America, it is still in its infancy in France and new within haematology.

β2-microglobulin triggers NLRP3 inflammasome activation in tumor-associated macrophages to promote multiple myeloma progression

As substantial constituents of the multiple myeloma (MM) microenvironment, pro-inflammatory macrophages have emerged as key promoters of disease progression, bone destruction, and immune impairment. We identify beta-2-microglobulin (β2m) as a driver in initiating inflammation in myeloma-associated macrophages (MAMs). Lysosomal accumulation of phagocytosed β2m promotes β2m amyloid aggregation in MAMs, resulting in lysosomal rupture and ultimately production of active interleukin-1β (IL-1β) and IL-18. This process depends on activation of the NLRP3 inflammasome after β2m accumulation, as macrophages from NLRP3-deficient mice lack efficient β2m-induced IL-1β production. Moreover, depletion or silencing of β2m in MM cells abrogates inflammasome activation in a murine MM model. Finally, we demonstrate that disruption of NLRP3 or IL-18 diminishes tumor growth and osteolytic bone destruction normally promoted by β2m-induced inflammasome signaling. Our results provide mechanistic evidence for β2m's role as an NLRP3 inflammasome activator during MM pathogenesis. Moreover, inhibition of NLRP3 represents a potential therapeutic approach in MM.

Abstract LB007: CFT7455: A novel, IKZF1/3 degrader that demonstrates potent tumor regression in IMiD-resistant multiple myeloma (MM) xenograft models

Abstract Introduction Ikaros family zinc finger protein 1 and 3 (IKZF1/3) are essential transcription factors (TF) for terminal differentiation of B and T cells. Depletion of IKZF1/3 in MM cells inhibits growth, confirming their dependency on IKZF1/3. IMiDs (lenalidomide[len], pomalidomide[pom]) are effective therapies for treatment of MM and promote degradation of IKZF1/3 via their interaction with CRL4-CRBN E3 ligase. Most patients treated with len or pom eventually develop progressive disease due to acquired resistance, underscoring an unmet medical need. CFT7455 is a novel IKZF1/3 degrader optimized for high affinity cereblon (CRBN) binding, rapid IKZF1/3 degradation, and potent in vivo efficacy. Results CFT7455 demonstrated an 800 to 1600-fold improvement in CRBN binding compared to pom in biochemical and cellular NanoBRET assays, respectively. In H929 MM cells expressing HiBiT-tagged IKZF1, CFT7455 induced &amp;gt;75% degradation of IKZF1 within 1.5 hr. The high binding affinity and degradation catalysis shown with CFT7455 enabled potent antiproliferative activity across a panel of MM cell lines as well as H929 cells made resistant to IMiDs. In RPMI-8226 MM mice xenografts, CFT7455 (0.1 mg/kg/day) resulted in deep, durable degradation of IKZF3 (21% and 9.5% of vehicle levels at 4 and 24 hr, respectively). Protein levels for IRF4, an essential TF in MM, declined over 7 days with daily CFT7455 treatment to 8% of vehicle levels. Dose dependent efficacy ranged from 0.003-0.1 mg/kg/day, with tumor regression evident at doses ≥0.01 mg/kg/day. Pom was inactive in this model at a human equivalent dose (3 mg/kg/day), with no observed tumor shrinkage in these mice following 17 days of dosing. Switching pom treatment to CFT7455 (0.1 mg/kg/day) on Day 18 led to tumor regression in 67% of animals on Day 28 and 100% tumor regression on Day 35, demonstrating that CFT7455 penetrates large tissues and is efficacious in rapidly growing, IMiD resistant tumors. In the H929 tumor xenograft model, administration of CFT7455 (0.1 mg/kg/day) promoted tumor regression (95% tumor growth inhibition by 7 days); dosing was stopped after 21 days. On Day 63, half the tumors remained below their starting tumor volume. Additionally, CFT7455 demonstrated durable tumor regression in the aggressive MM1.S systemic MM tumor model. In mice bearing RPMI-8226 xenograft tumors, the combination of CFT7455 (QD) and dexamethasone (QW) was more active, and demonstrated a significant survival improvement, compared to either agent alone. Conclusions CFT7455 is a highly potent, catalytic degrader of IKZF1/3, with marked antitumor activity as a single agent and in combination with dexamethasone. Importantly, CFT7455 retains activity in models resistant or insensitive to IMiDs. These results warrant investigation of CFT7455 as a therapeutic approach for MM and a clinical study is planned. Citation Format: James A. Henderson, R. Jason Kirby, Samantha Perino, Roman V. Agafonov, Prasoon Chaturvedi, Bradley Class, David Cocozziello, Scott J. Eron, Andrew Good, Ashley A. Hart, Christina Henderson, Marta Isasa, Brendon Ladd, Matt Schnaderbeck, Michelle Mahler, Roy M. Pollock, Adam S. Crystal, Christopher G. Nasveschuk, Andrew J. Phillips, Stewart L. Fisher, David A. Proia. CFT7455: A novel, IKZF1/3 degrader that demonstrates potent tumor regression in IMiD-resistant multiple myeloma (MM) xenograft models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB007.