Evaluation of the TPO-receptor agonist Eltrombopag in the Pediatric Preclinical Testing Consortium osteosarcoma in vivo models.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e22502-e22502
Author(s):  
Michael Roth ◽  
Grace Nevil ◽  
Jonathan Benjamin Gill ◽  
Wendong Zhang ◽  
Beverly A. Teicher ◽  
...  
Keyword(s):  
Tumor Growth ◽  
High Dose ◽  
Osteosarcoma Cells ◽  
Time To Event ◽  
Preclinical Testing ◽  
In Vivo Models ◽  
Platelet Recovery ◽  
Polyvalent Cations ◽  
Pdx Models

e22502 Background: Eltrombopag (EP) is a small molecule, thrombopoietin receptor (TPO-R) agonist indicated for the treatment of patients with chronic immune thrombocytopenia and severe aplastic anemia. EP is a polyvalent cation chelator and inhibits leukemia cell proliferation via depletion of intracellular iron. Recent studies show EP inhibits the proliferation of osteosarcoma cells lines via depletion of polyvalent cations. The in vivo effects of EP were studied in osteosarcoma patient derived xenograft models by the Pediatric Preclinical Testing Consortium (PPTC). Methods: The in vivo anticancer effects of EP were assessed in a panel of six osteosarcoma PPTC PDX models with limited MPL mRNA expression (OS2, OS9, OS31, OS33, OS36, OS60). EP was administered at an oral dose of 5 mg/kg/day given for 5 days each week with planned treatment period of 4 weeks. High dose EP (50mg/kg/day) was also tested in 2 PDX models (OS2, OS9) on the same schedule. A control cohort that received vehicle was included for each PDX model. Tumor volumes were measured and responses defined utilizing the PPTC statistical analyses. Results: EP at 5 mg/kg failed to inhibit tumor growth or induce significant differences in event-free survival (EFS) in any of the 6 osteosarcoma PDX models. At the higher dose of 50 mg/kg a significant prolongation in time to event in the EP-treated group was observed, but the effect was small with the ratio of the median time to event for treated versus control animals (EFS T/C) being only 1.2 in the 2 OS PDX models tested. No objective responses were observed with EP at either dose, with all models demonstrating progressive disease. Conclusions: EP did not exhibit significant antitumor activity against the PPTC osteosarcoma PDX panel. However, EP also did not enhance tumor growth. EP’s lack of anti-tumor activity against the OS PDX models suggests leukemia and osteosarcoma cells likely have different dependencies on intracellular polyvalent cations. Given EPs effect on stimulating platelet production, and the demonstration that EP does not stimulate in vivo growth of osteosarcoma, EP may be considered in patients with osteosarcoma as a supportive care agent in supporting platelet recovery.

Evaluation of the multi-kinase inhibitor regorafenib in the Pediatric Preclinical Testing Consortium osteosarcoma, rhabdomyosarcoma, and Ewing sarcoma in vivo models.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. 10038-10038
Author(s):  
Douglas James Harrison ◽  
Jonathan Benjamin Gill ◽  
Michael Roth ◽  
Wendong Zhang ◽  
Beverly Teicher ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Ewing Sarcoma ◽  
Kinase Inhibitor ◽  
Objective Response ◽  
Primary Treatment ◽  
Tumor Growth Inhibition ◽  
Oral Gavage ◽  
Preclinical Testing ◽  
In Vivo Models

10038 Background: Regorafenib is a multi-kinase inhibitor, developed by adding a fluorine atom to the phenyl ring of sorafenib. Regorafenib inhibits multiple kinases including BRAF, FGFR1, KIT, PDGFRB, RAF, RET, and VEGFR1-3, many at a higher potency than sorafenib. Prior studies within the Pediatric Preclinical Testing Consortium (PPTC) demonstrated sorafenib exhibited intermediate activity for tumor growth inhibition in more than 50% of the sarcoma models tested at a dose of 60mg/kg by oral gavage daily (5 days/wk for 6 consecutive weeks). The in vivo effects of regorafenib were studied in the PPTC osteosarcoma (OS), rhabdomyosarcoma (Rh) and Ewing (EW) sarcoma xenograft models. Methods: The in vivo anticancer effects of regorafenib were assessed in a panel of 6 osteosarcoma models (OS2, OS9, OS31, OS33, OS36, OS60), two rhabdomyosarcoma models (Rh30, Rh41), and one Ewing sarcoma model (EW5). Regorafenib was administered by oral gavage at a dose of 30 mg/kg/day given daily for 21 consecutive days. Time to event and tumor volume responses were defined and analyzed utilizing standard PPTC statistical methods. Results: Regorafenib induced significant improvements in event-free survival (EFS) compared to control in 100% (9/9) of sarcoma models tested. Most models showed pronounced slowing of tumor growth compared to control during the 21 days of regorafenib treatment, with tumor growth generally approximating control rates soon after completion of regorafenib treatment. Three out of 8 sarcoma models demonstrated EFS T/C values > 2 (1/6 OS, 2/2 Rh, 0/1 EW). Minimum relative tumor volumes ranged from 0.74 to 1.60, with no models meeting criteria for objective response. Conclusions: Regorafenib induced modest inhibition of tumor growth in the PPTC sarcoma models evaluated. The overall pattern of response to the multi-kinase inhibitor regorafenib against the PPTC sarcoma models appears similar to that of the kinase inhibitor sorafenib, with pronounced slowing of tumor growth in some models that is limited to the period of agent administration being the primary treatment effect.

Melatonin modifies tumor hypoxia and metabolism by inhibiting HIF-1α and energy metabolic pathway in the in vitro and in vivo models of breast cancer

2019 ◽  
Vol 2 (4) ◽  
pp. 83-98 ◽  
Author(s):  
André De Lima Mota ◽  
Bruna Vitorasso Jardim-Perassi ◽  
Tialfi Bergamin De Castro ◽  
Jucimara Colombo ◽  
Nathália Martins Sonehara ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Glucose Metabolism ◽  
Tumor Growth ◽  
Tumor Cells ◽  
Carbonic Anhydrases ◽  
In Vivo Models ◽  
Ca Ix ◽  
Gene And Protein Expression

Breast cancer is the most common cancer among women and has a high mortality rate. Adverse conditions in the tumor microenvironment, such as hypoxia and acidosis, may exert selective pressure on the tumor, selecting subpopulations of tumor cells with advantages for survival in this environment. In this context, therapeutic agents that can modify these conditions, and consequently the intratumoral heterogeneity need to be explored. Melatonin, in addition to its physiological effects, exhibits important anti-tumor actions which may associate with modification of hypoxia and Warburg effect. In this study, we have evaluated the action of melatonin on tumor growth and tumor metabolism by different markers of hypoxia and glucose metabolism (HIF-1α, glucose transporters GLUT1 and GLUT3 and carbonic anhydrases CA-IX and CA-XII) in triple negative breast cancer model. In an in vitro study, gene and protein expressions of these markers were evaluated by quantitative real-time PCR and immunocytochemistry, respectively. The effects of melatonin were also tested in a MDA-MB-231 xenograft animal model. Results showed that melatonin treatment reduced the viability of MDA-MB-231 cells and tumor growth in Balb/c nude mice (p <0.05). The treatment significantly decreased HIF-1α gene and protein expression concomitantly with the expression of GLUT1, GLUT3, CA-IX and CA-XII (p <0.05). These results strongly suggest that melatonin down-regulates HIF-1α expression and regulates glucose metabolism in breast tumor cells, therefore, controlling hypoxia and tumor progression. 

scholarly journals Tumor Suppressor Function of miR-127-3p and miR-376a-3p in Osteosarcoma Cells

Cancers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2019 ◽  
Author(s):  
Joerg Fellenberg ◽  
Burkhard Lehner ◽  
Heiner Saehr ◽  
Astrid Schenker ◽  
Pierre Kunz
Keyword(s):  
Tumor Suppressor ◽  
Therapeutic Strategies ◽  
High Dose ◽  
Osteosarcoma Cell ◽  
Tumor Suppressor Function ◽  
Osteosarcoma Cells ◽  
Aberrant Expression ◽  
Suppressor Function

Since the introduction of high-dose chemotherapy about 35 years ago, survival rates of osteosarcoma patients have not been significantly improved. New therapeutic strategies replacing or complementing conventional chemotherapy are therefore urgently required. MicroRNAs represent promising targets for such new therapies, as they are involved in the pathology of multiple types of cancer, and aberrant expression of several miRNAs has already been shown in osteosarcoma. In this study, we identified silencing of miR-127-3p and miR-376a-3p in osteosarcoma cell lines and tissues and investigated their role as potential tumor suppressors in vitro and in vivo. Transfection of osteosarcoma cells (n = 6) with miR-127-3p and miR-376a-3p mimics significantly inhibited proliferation and reduced the colony formation capacity of these cells. In contrast, we could not detect any influence of miRNA restoration on cell cycle and apoptosis induction. The effects of candidate miRNA restoration on tumor engraftment and growth in vivo were analyzed using a chicken chorioallantoic membrane (CAM) assay. Cells transfected with mir-127-3p and miR-376a-3p showed reduced tumor take rates and tumor volumes and a significant decrease of the cumulative tumor volumes to 41% and 54% compared to wildtype cells. The observed tumor suppressor function of both analyzed miRNAs indicates these miRNAs as potentially valuable targets for the development of new therapeutic strategies for the treatment of osteosarcoma.

scholarly journals The effects of recombinant human GH on promoting tumor growth depend on the expression of GH receptor in vivo

2011 ◽  
Vol 211 (3) ◽  
pp. 249-256 ◽  
Author(s):  
Yan Lin ◽  
Suyi Li ◽  
Peng Cao ◽  
Lu Cheng ◽  
Ming Quan ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Tumor Growth ◽  
Safety Concern ◽  
Severe Malnutrition ◽  
High Dose ◽  
Gastric Adenoma ◽  
Malignant Diseases ◽  
Gh Receptor ◽  
Tumor Bearing

Cancer-related malnutrition is a mortal threat to gastric carcinoma patients. However, conventional nutrition treatment is not effective for recovery. Recombinant human GH (rhGH) is widely accepted clinically to treat severe malnutrition caused by non-malignant diseases, but not approved to treat malignant diseases due to the safety concern. To explore the safety of rhGH on gastric cancer, we assessed the effect of rhGH on two tumor-bearing mice modelsin vivoestablished by human gastric adenoma cell lines of SGC-7901 and MKN-45. VEGF expression in tumor tissues was detected using immunohistochemistry. The expression of GH receptor (Ghr),Jak-2,Stat3,Vegf, Hif-1α, Fgf, andMmp-2was measured by RT-PCR and protein expression of STAT3, phosphorylated STAT3, VEGF, HIF-1α, and MMP-2 was measured by western blotting. The immunocytochemistry results showed that the GHR expression of SGC-7901 was strongly positive (GHR+++), while GHR expression of MKN-45 was regarded as negative (GHR−). After 14 days of rhGH treatment in SGC-7901 (GHR+++) tumor-bearing mice, we found that the tumor growth was significantly increased, and the expressions of downstream factors and VEGF were increased. However, in MKN-45 (GHR−) tumor-bearing mice, tumor growth was not significantly increased by rhGH, but tumor-free body weight was increased especially in high-dose rhGH-treated group (P<0.05). These findings suggest that the level of GHR expression is a key target that influences the effectiveness of rhGH on promoting the growth of gastric cancer and angiogenesis. rhGH may promote the activation of tumor angiogenesis factors through the Jak-2–STAT3 pathway.

LncRNA GAS5 suppresses the proliferation and invasion of osteosarcoma cells via the miR-23a-3p/PTEN/PI3K/AKT pathway

2020 ◽  
Author(s):  
Jianmin Liu ◽  
Ming Chen ◽  
Longyang Ma ◽  
Xingbo Dang ◽  
Gongliang Du
Keyword(s):  
Tumor Suppressor ◽  
Tumor Growth ◽  
Akt Pathway ◽  
Osteosarcoma Cell ◽  
Osteosarcoma Cells ◽  
Cell Behaviors ◽  
Human Osteosarcoma ◽  
Proliferation And Invasion

Abstract Background: Accumulating evidence has shown that lncRNA growth arrest special 5 (GAS5) is a well‑known tumor suppressor in the pathogenesis of a variety of human cancers. However, the detailed role of GAS5 in osteosarcoma is largely unclear. Here, we explore the role of GAS5 in progression of osteosarcoma. Methods: The expression level of GAS5 was detected in human osteosarcoma tissues and matched adjacent tissues, as well as osteosarcoma cell lines and non-malignant osteoblast cells. Then, in vitro gain- and loss-of-function experiments, with the pcDNA-GAS5 expression vector and GAS5-siRNA, were performed in U2OS and HOS cells to determine the effect of GAS5 on osteosarcoma cell proliferation and invasion. Subsequently, we searched potential miRNA targets with bioinformatics analysis and confirmed their interaction by using luciferase reporter gene and RNA pull-down assays. The function and mechanism of miR-23a-3p in proliferation and invasion was also investigated in U2OS and HOS cells. Furthermore, rescue experiments were performed to verify the involvement of miR-23a-3p and its target gene in GAS5-mediated cell behaviors. Finally, a xenograft nude mouse model was established by subcutaneous injection with U2OS cells overexpressing GAS5 or not, and the effect of GAS5 on tumor growth in vivo was evaluated. Results: GAS5 was downregulated in human osteosarcoma tissues and cell lines. Overexpression of GAS5 could significantly suppress, and downregulation of GAS5 promoted, proliferation and invasion of osteosarcoma cells. GAS5 could directly bind with and downregulated miR-23a-3p that post-transcriptionally downregulated the tumor suppressor PTEN and positively regulated proliferation and invasion of osteosarcoma cells. Rescue experiments confirmed the involvement of miR-23a-3p and PTEN in GAS5-mediated cell behaviors by modifying the phosphatidylinositol-3-kinases/protein-serine-threonine kinase (PI3K/AKT) pathway. GAS5 could inhibit tumor growth in vivo . Conclusion: GAS5 functions as a competing endogenous RNA , sponging miR-23a-3p, to promote PTEN expression and suppress cell growth and invasion in osteosarcoma by regulating the PI3K/AKT pathway.

scholarly journals Atovaquone Suppresses Triple-Negative Breast Tumor Growth by Reducing Immune-Suppressive Cells

2021 ◽  
Vol 22 (10) ◽  
pp. 5150
Author(s):  
Nehal Gupta ◽  
Shreyas Gaikwad ◽  
Itishree Kaushik ◽  
Stephen E. Wright ◽  
Maciej M. Markiewski ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Cancer Progression ◽  
Breast Tumor ◽  
Triple Negative ◽  
Immune Surveillance ◽  
Suppressor Cells ◽  
Myeloid Derived Suppressor Cells ◽  
In Vivo Models ◽  
Ribosomal Protein S19

A major contributing factor in triple-negative breast cancer progression is its ability to evade immune surveillance. One mechanism for this immunosuppression is through ribosomal protein S19 (RPS19), which facilitates myeloid-derived suppressor cells (MDSCs) recruitment in tumors, which generate cytokines TGF-β and IL-10 and induce regulatory T cells (Tregs), all of which are immunosuppressive and enhance tumor progression. Hence, enhancing the immune system in breast tumors could be a strategy for anticancer therapeutics. The present study evaluated the immune response of atovaquone, an antiprotozoal drug, in three independent breast-tumor models. Our results demonstrated that oral administration of atovaquone reduced HCC1806, CI66 and 4T1 paclitaxel-resistant (4T1-PR) breast-tumor growth by 45%, 70% and 42%, respectively. MDSCs, TGF-β, IL-10 and Tregs of blood and tumors were analyzed from all of these in vivo models. Our results demonstrated that atovaquone treatment in mice bearing HCC1806 tumors reduced MDSCs from tumor and blood by 70% and 30%, respectively. We also observed a 25% reduction in tumor MDSCs in atovaquone-treated mice bearing CI66 and 4T1-PR tumors. In addition, a decrease in TGF-β and IL-10 in tumor lysates was observed in atovaquone-treated mice with a reduction in tumor Tregs. Moreover, a significant reduction in the expression of RPS19 was found in tumors treated with atovaquone.

High Efficacy and Good Tolerability with Rituximab In Vivo Purging Followed by High Dose Chemotheraphy and Autologous Peripheral Blood Stem Cell Transplantation (APBSCT) in Non-Hodgkin’s Lymphoma (NHL).

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4626-4626
Author(s):  
Yuankai Shi ◽  
Sheng Yang ◽  
Xiaohong Han ◽  
Peng Liu ◽  
Xiaohui He ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Overall Survival ◽  
Complete Remission ◽  
Minimal Residual Disease ◽  
Median Time ◽  
Residual Disease ◽  
High Dose ◽  
Platelet Recovery ◽  
Minimal Residual

Abstract Purpose: High-dose chemotherapy (HDC) supported by APBSCT has been shown to be superior to standard therapy in NHL. However, many patients relapse due to minimal residual disease (MRD) in vivo or in the graft. Rituximab has the potential to clear both blood and bone marrow of malignant CD20+ cells, prompting this multicenter trial of in vivo purging with rituximab and HDC with APBSCT in China. Methods: Cyclophosphamide 4g/m2 was used as the mobilization regimen, CY/TBI, BEAM or CBV could be used as HDC at the discretion of the institution. Four infusions of rituximab (375 mg/m2) were given: one day before mobilization, one day before harvesting, one day before transplantation and on day 8 after transplantation. BCL-2/Ig-H translocation was measured as a marker of minimal residual disease in blood or bone marrow before mobilization and during transplantation using real-time quantitative PCR. Results: Thirty-one patients from 12 centers with histologically proven CD20+ NHL (28 aggressive, 3 indolent NHL) were enrolled. Twenty-four patients were previously untreated, and 7 patients had relapsed disease. Median yields of CD34+ cells and mononuclear cells were 5.9×106/kg and 4.4×108 /kg respectively. Median time to recovery of WBC >1.5×109/L, ANC >0.5×109/L and platelets >20×109/L after APBSCT was 10 days in each case. Median time to platelet recovery >50×109/L was 13 days. Generally, this therapeutic strategy was well tolerated with few side effects attribute to rituximab. All patients achieved a complete remission after APBSCT. At a median-follow-up of 12 months, overall survival and progression-free survival (PFS) are 87% and 73% respectively for all patients. In patients with aggressive NHL, overall survival and PFS are 85% and 73% respectively and in indolent NHL are 100% and 67% respectively. PFS and overall survival were slightly higher in previously untreated compared with relapsed patients (88% vs. 83% for PFS, 73% vs. 69% for overall survival). One of five 5 patients who were initially found to be PCR-positive and achieved PCR-negative status subsequently experienced progression accompanied by a return to PCR positivity. The remaining four patients are still in complete remission and are PCR negative. Conclusion: These results suggest that the regimen of rituximab combined with HDCT and APBSCT is effective and well tolerated for the treatment of patients with NHL.

Therapeutic Efficacy and Cure Of Sensitive and T315I Pan-Resistant Human Ph+ Leukemia In Mice Using a TCR-Like Antibody To WT1/HLA-A0201 Alone, Or In Combination With Tyrosine Kinase Inhibitors

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 855-855
Author(s):  
Leonid Dubrovsky ◽  
Elliott Brea ◽  
Dmitry Pankov ◽  
Nicholas Veomett ◽  
Tao Dao ◽  
...  
Keyword(s):  
Combination Therapy ◽  
Tyrosine Kinase ◽  
Tumor Growth ◽  
Cell Line ◽  
Wilms Tumor ◽  
High Dose ◽  
Human Leukemia ◽  
Rt Pcr

Abstract Acute and chronic leukemias, including CD34+ CML stem cells, overexpress the Wilms tumor gene 1 (WT1) protein, making WT1 an attractive therapeutic target. ESKM is a fully human IgG1 antibody that targets a 9 amino acid sequence (RMF) of the protein WT1 in the context of HLA-A0201, allowing it to target an undruggable, widely expressed, intracellular oncogene product. BV173 is an HLA-A0201+, human Ph+ ALL cell line that expresses WT1, and tagged by our lab with luciferase. We engineered a tyrosine kinase inhibitor (TKI) resistant BV173-R cell line by transducing BV173 with the resistant T315I Bcr-Abl plasmid. Antibody-dependent cellular cytotoxicity (ADCC) was evaluated in vitro by chromium release assay, utilizing human PBMC effectors. Tumor growth in vivo was assessed in NOD/SCID gamma (NSG) mice with bioluminescence imaging (BLI). RT-PCR was used to evaluate minimal residual disease in mice with negative BLI signal at the end of therapy. Imatinib, dasatinib, and ponatinib were used at up to maximally tolerated doses, given IP once daily. ESKM was administered at 100 µg twice weekly IP. ESKM mediated ADCC against both BV173 and BV173-R cell lines in vitro. In a BV173 engrafted human leukemia xenograft model, ESKM was more potent than imatinib, with median tumor growth reduction of 78% vs 52%. Combination of imatinib and ESKM therapy resulted in a 94% reduction in leukemic growth. High dose dasatinib (40 mg/kg daily) was more potent than ESKM, but discontinuation of therapy due to dasatinib toxicity resulted in relapse. Combination with ESKM therapy with dasatinib resulted in cure in 75% of mice, confirmed by bone marrow RT-PCR three weeks after termination of therapy. For mice cytoreduced with dasatinib followed by consolidation therapy with ESKM, delayed relapse was observed, but no cures. ESKM was highly superior to imatinib and dasatinib against the T315I BV173-R leukemia in vivo. Cures were not achieved with combination therapy of ESKM and either first or second generation TKIs against resistant T315I leukemia. Ponatinib at 10 mg/kg had higher efficacy than ESKM alone against BV173-R, but mice treated with combination of ESKM and ponatinib had superior tumor reduction. CONCLUSION: ESKM is an effective therapeutic antibody for sensitive and T315I Ph+ ALL. Resistant T315I Ph+ leukemic growth is inhibited more effectively by ESKM therapy compared to imatinib and dasatinib, and combination therapy with ESKM is superior to ponatinib. Supported by the Leukemia and Lymphoma Society, NIH R01CA55349, P01 23766 and T32CA62948-18. Disclosures: Yan: Eureka Therapeutics: Employment. Liu:Eureka Therapeutics: Employment, Equity Ownership.

Novel Patient Derived Multiple Myeloma Model Reflects Sensitivity Towards Anticancer Treatment in Multiple Myeloma Patients

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3004-3004 ◽  
Author(s):  
Julia B. Schueler ◽  
Dagmar Wider ◽  
Kerstin Klingner ◽  
Gabrielle Melanie Siegers ◽  
Annette M May ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Flow Cytometry ◽  
Tumor Growth ◽  
Treatment Options ◽  
Tumor Biology ◽  
Pdx Model ◽  
Anticancer Treatment ◽  
Nog Mice ◽  
Pdx Models

Abstract Background Appropriate animal models for hematological malignancies are highly attractive, because they allow the study of the tumor biology and underlying disease mechanisms. They also constitute a major prerequisite for rapid bench-to-bedside translation of investigational anticancer therapies. To validate our multiple myeloma patient (pt)-derived xenograft (MM PDX) model (Schueler et al, Expert Opin Biol Ther, 2013), we systematically analyzed a panel of MM PDX with regard to their sensitivity towards standard of care treatment and compared these data with the pts' clinical outcome. Methods Bone marrow (BM) cells of 11 MM pts were implanted intratibialy (i.t.) into 103 NOD/Shi-scid/IL-2Rγnull (NOG) mice (n= 6-18 / pt sample). Mice were treated according to pts' therapy with VCD (Bortezomib, Cyclophosphamide, Dexamethasone), or to evaluate additional treatment options with Rd (Lenalidomide, Dexamethasone). Tumor growth and antitumoral activity in mice were assessed in tumor-bearing mice and compared to untreated control mice as well as to pts' response. Tumor growth in the mouse model was monitored by whole-body fluorescence-based in-vivo-imaging (IVI) using CF750-labeled α-HLA ABC antibody before and during treatment as well as 24h after last treatment cycle as described (Schueler J. PLOSone 2013). Mock-injected animals served as negative controls. Engraftment of human MM cells in murine organs was confirmed by flow cytometry and patho-histological analyses (immunostaining) at the end of the study. Results The pt cohort included a typical MM clientele for referral centers, with a median age of 75 years (range 56-85), median BM infiltration of 80% (20-90), and high- and standard-risk cytogenetics in 5 and 6 pts, respectively. All pts had advanced disease with Durie&Salmon stage III and active/symptomatic MM. All pts received VCD after diagnosis and BM sampling. MM cell engraftment could reliably be determined from experimental day 10 on in all 11 MM PDX models, at all assessed sites, namely within the BM, spleen and peripheral blood (PB) of recipient mice. Individual pt samples displayed distinct tumor growth patterns in vivo. Fluorescence intensity of engrafted murine organs ranged from 2- to 15-fold compared to mock injected control mice. Mean IVI signals in BM of recipient mice were 10-fold higher as compared to spleen signals, qualifying the BM niche as the preferred homing localization of pts' MM cells. Of note, both injected and non-injected BM sites were infiltrated by MM cells 10 days after tumor cell injection. Engraftment of human MM cells in the respective murine organs was confirmed by flow cytometry (HLA ABC, CD138, CD38) and histology and verified MM engraftment via both methods, confirming prior reports (Schüler PLOSone 2013; Groen Blood 2012;120:e9-16, Overdijk MAbs. 2015;7:311-21). The murine engraftment capacity was independent of MM type, disease stage, BM infiltration and cytogenetics of the donor pt. VCD was applied to 9 different MM PDX models and induced partial remission (PR; defined as at least 50% reduction of murine tumor load in BM, spleen and/or PB) in 5 out of 9 tested MM PDX models, whereas 2 cases each showed stable disease (SD) or progression (PD). The response rates in the mouse avatars mirrored the clinical outcome of the respective MM pts in 8/9 cases; only one MM pt showed serological and clinical PR, whereas the corresponding mice displayed SD. Rd induced PR in 1 and PD in a second MM PDX model, underlining the feasibility of MM PDX for drug screening approaches. Conclusions Due to the complex tumor biology, murine models of MM are still challenging. Our data support the preclinical rationale to use i.t.-injected NOG mice, since they closely resemble clinical MM with respect to symptoms, disseminated disease sites and response to anticancer treatment. Possible applications for the MM mouse avatars include development of new anticancer drugs as well as definition of biomarker strategies and selection of treatment options for individual pts with relapsed/refractory MM. The data of our preclinical study may serve as a useful future strategy to guide treatment decisions in refractory pts. The suitability as a drug development tool will be additionally determined performing treatment experiments with novel agents, e.g. elotuzumab or daratumumab. Disclosures Schueler: Oncotest GmbH: Employment. Klingner:Oncotest GmbH: Employment.

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