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Supplementary Figure 2 - PDF file 50K, Accessory cells protect MM cells from WT-1 specific CTLs. U266 cells were co-cultured with WT-1 specific T cells in presence and absence of different accessory cells. MM cell viability was determined 24h after addition of T cells by CS-BLI (A). Granzyme B production in the supernatant was determined by ELISA (B). Significance of inhibition of MM cell survival in the presence of accessory cells was tested by unpaired two tailed student's t test. *= p

Supplementary Figure 1 - PDF file 53K, Antigen specific, HLA-restricted and dose-dependent recognition of the MM cell lines U266 and UM9, but not of accessory cells by CD8+ and CD4+ mHag-specific CTLs. The CD4+ (A) and CD8+ (B) CTLs were co-cultured with the luc+ MM cell lines UM9 and U266 in different effector to target ratios. The HLA- and mHag typing of these MM cell lines are indicated. MM cell survival was determined 24 h after addition of T cells by CS-BLI. Results represent the mean values of triplicate cultures (+/- SEM). Results are representative of 3 independent assays. In (C and D) CD4+ (C) and CD8+ (D) CTLs were co-cultured with accessory cells. Accessory cell survival was determined 24h after addition of T cells by FACS annexine V/ propidium iodide staining of CD4 and CD8 negative cells in the co-cultures. Results are depicted as % surviving cells, measured as relative number annexin V/propidium iodide negative cells, compared to no T cells control

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Supplementary Figure 3 - PDF file 55K, RGDw reduces adhesion of MM cells to accessory cells. Adherent HS-5 en HUVEC accessory cells were incubated with RGDw or an irrelevant peptide for 1hour. After washing away the unbound peptide, UM9 (A) or U266 (B) cells were added and incubated overnight. Plates were reversely centrifuged to determine adhesion to accessory cells. Results represent the mean values of triplicate cultures (+/- SEM). Differences in adhesion were tested by unpaired two tailed student's t test. *= p

PDF file - 111K, GVHD and GvT regulation in the LME-1 MM tumor model. (A) GvHD scores at weeks 3, 4,and 5. The total score is the sum of the scores for weight loss ( 0=0-10 %; 1=10-20%; 2=>20%. ) , mobility (0= mobile; 1= diminished mobility;2 = immobile) and fur appearance (0=normal; 1= ruffled fur; 2= ruffled fur + red swollen skin; 3= ruffled fur + red swollen skin + patchy alopecia) (B) CD4 and CD8 T cell counts in peripheral blood, BM and spleen at week 3. (C) BLI imaging results of three representative animals per group at week 3. The depicted areas indicate the regions of extramedullar vs medullar tumors . The BLI counts in the corresponding table are in thousands. For each mouse total, extramedullary, and medullary ( total-extramedullary) tumor load are indicated separately. The mean values of the ratio of extramedullary vs medullary tumor load are also depicted.

Supplementary Figure 5 - PDF file 41K, Bortezomib does not improve the CTL mediated lysis of Fas negative L363 cellsL3L3 reactive CD8+CTLs were incubated at the indicated effector to target ratios with luc-transduced L3L3 cells alone or in the presence of various dilutions of bortezomib. The CTL mediated and bortezomib mediated lysis of L3L3 cells was determined after 48 hours by BLI. Results are depicted as % surviving cells using the triplicate cultures without T cells and bortezomib as the 100% survival control

Purpose: Cellular immunotherapy frequently fails to induce sustained remissions in patients with multiple myeloma, indicating the ability of multiple myeloma cells to evade cellular immunity. Toward a better understanding and effective therapeutic modulation of multiple myeloma immune evasion mechanisms, we here investigated the role of the tumor microenvironment in rendering multiple myeloma cells resistant to the cytotoxic machinery of T cells.Experimental Design: Using a compartment-specific, bioluminescence imaging-based assay system, we measured the lysis of luciferase-transduced multiple myeloma cells by CD4+ or CD8+ CTLs in the presence versus absence of adherent accessory cells of the bone marrow microenvironment. We simultaneously determined the level of CTL activation by measuring the granzyme B release in culture supernatants.Results: Bone marrow stromal cells from patients with multiple myeloma and healthy individuals, as well as vascular endothelial cells, significantly inhibited the lysis of multiple myeloma cells in a cell–cell contact-dependent manner and without substantial T-cell suppression, thus showing the induction of a cell adhesion-mediated immune resistance (CAM-IR) against CTL lysis. Further analyses revealed that adhesion to accessory cells downregulated Fas and upregulated the caspase-3 inhibitor survivin in multiple myeloma cells. Reconstitution of Fas expression with bortezomib enhanced the CTL-mediated lysis of multiple myeloma cells. Repressing survivin with the small-molecule YM155 synergized with CTLs and abrogated CAM-IR in vitro and in vivo.Conclusion: These results reveal the cell adhesion-mediated induction of apoptosis resistance as a novel immune escape mechanism and provide a rationale to improve the efficacy of cellular therapies by pharmacologic modulation of CAM-IR. Clin Cancer Res; 19(20); 5591–601. ©2013 AACR.

Supplementary Figure Legends - PDF file 73K, Legends for supplementary figures

PDF file - 49K, Ex vivo expansion and suppressor capacity of Tregs. (A) Ex vivo expansion rate of CD4+CD25+ Tregs isolated from peripheral blood. (B) Suppressive activity of ex vivo cultured Tregs on CD4+CD25- effector T cells stimulated with CD3/CD28 expander beads. Ex vivo cultures and suppression assays were executed as indicated in the material and methods section. Presented data are representative of >5 individual Treg cultures from different donors. Error bars indicate the SEM of at least duplicate measurements. The expanded Treg cultures contained 70% +/- 3% Foxp3+ T cells which were also negative for CD127. The cultures also contained 4.5+/-3.6 % IL-17 producing cells as detected after stimulation with PMA/Ionomycin (see also ref 20)

Supplementary Figure 6 - PDF file 74K, Synergistic interaction of YM155 and CTLs. In A, the effect of YM155 on survivin and MCL-1 protein levels of MM cells is shown. The cells were cultured with YM155 during 24h and the western blot assays were carried out as indicated in material methods. Band intensities were quantified using image J software, calculated as relative values to the control protein tubuline and plotted as relative to the expression levels of cells cultured without YM155. In B, the type of interaction between YM155 and CTLs (see figure 5C-D) in the presence of accessory cells was analyzed using Compusyn software (version 1.0, 2004 �). In the plots (A) the CI values corresponding to the doses in figure 5 are shown. A CI value of 1 indicates synergy, additive effects or antagonism, respectively. In C the supernatants of assays as described in Fig 5C-D granzyme B release was measured using ELISA (B). Results are expressed as the mean values of the triplicate cultures. Error bars represent the SEM. Results are representative of 3 independent assays

Purpose: Regulatory T cells (Tregs) are potent tools to prevent graft-versus-host disease (GVHD) induced after allogeneic stem cell transplantation or donor lymphocyte infusions. Toward clinical application of Tregs for GVHD treatment, we investigated the impact of Tregs on the therapeutic graft-versus-tumor (GVT) effect against human multiple myeloma tumors with various immunogenicities, progression rates, and localizations in a humanized murine model.Experimental Design: Immunodeficient Rag2−/−γc−/− mice, bearing various human multiple myeloma tumors, were treated with human peripheral blood mononuclear cell (PBMC) alone or together with autologous ex vivo cultured Tregs. Mice were analyzed for the in vivo engraftment, homing of T-cell subsets, development of GVHD and GVT. In additional in vitro assays, Tregs that were cultured together with bone marrow stromal cells were analyzed for phenotype and functions.Results: Treatment with PBMC alone induced variable degrees of antitumor response, depending on the immunogenicity and the growth rate of the tumor. Coinfusion of Tregs did not impair the antitumor response against tumors residing within the bone marrow, irrespective of their immunogenicity or growth rates. In contrast, Tregs readily inhibited the antitumor effect against tumors growing outside the bone marrow. Exploring this remarkable phenomenon, we discovered that bone marrow stroma neutralizes the suppressive activity of Tregs in part via production of interleukin (IL)-1β/IL-6. We furthermore found in vitro and in vivo evidence of conversion of Tregs into IL-17–producing T cells in the bone marrow environment.Conclusions: These results provide new insights into the Treg immunobiology and indicate the conditional benefits of future Treg-based therapies. Clin Cancer Res; 19(6); 1467–75. ©2012 AACR.

Supplementary Figure 4 - PDF file 219K, FasL upregulation on CTLs upon MM cell recognition is not hampered by presence of accessory cells. CD4+ (A) and CD8+ (B) CTLs were cultured alone (unstimulated) or in the presence of tumor cells and in presence or absence of accessory cells as indicated. After 3 hours of co-incubation CTLs were evaluated for CD178 (Fas ligand) expression. Percentage of FasL expressing cells is indicated

PDF file - 54K, Human Tregs allow GvT against murine lymphoma tumors. Human PBMC were infused alone or together with expanded human Tregs to treat immune deficient mice carrying murine Luciferase+ A20 lymphoma cells in the bone marrow. PBMC (n=10), PBMC + Treg (n=9), untreated control group (n=10) (A) Kaplan Meier survival curves of mice, which all were sacrificed due to paralysis ***, p

Multiple myeloma (MM), the second most common hematologic malignancy in adults, is characterized by clonal proliferation of malignant plasma cells and tumor-induced complications, including MM-induced bone disease (MBD). Up to 90% of MM patients develop MBD during the course of their disease, which is a major cause of morbidity and mortality. MM therapy focuses primarily on agents that seek to eradicate the tumor cells and others which inhibit bone resorption. In contrast, no drugs are currently available to promote bone formation in MM patients and reverse MBD. Towards addressing this unmet therapeutic need, we applied a modified version of our “humanized” bone marrow (BM)-like scaffold (huBMsc)-based xenograft model, where MM cells and bone marrow mesenchymal stromal cells (BMMSCs) are co-implanted. In this system, we investigated the impact of MM cells on BMMSCs to identify markers that can be targeted with the intent to reverse MBD. After confirming that MM cells indeed inhibit bone formation in vivo, we performed transcriptional analysis of ex vivo expanded “unexposed” control BMMSCs vs. “MM-exposed” BMMSCs and found 332 differentially expressed genes. Next, we compared these data with transcriptional profiles of BMMSCs after in vitro differentiation towards osteoblasts, as well as publicly available data of transcriptional profiles of BMMSCs obtained from MM, ALL, and AML patients. Combined, this analysis identified 8, MM-specific, differentially expressed genes, including the small leucine-rich proteoglycans (SLRPs), ASPN, OGN and OMD, that are 1) suppressed in the presence of MM (xenograft model and patient-derived BMMSCs); 2) induced during in vitro osteogenic differentiation; and 3) not dysregulated in BMMSCs in other hematological malignancies. As reported previously, we observed that bone morphogenetic protein (BMP)6 can upregulate the expression of these SLRPs in BMMSCs, while inducing osteogenic differentiation. Moreover, incubation of MM cells with BMP6 in either mono- or co-cultures with stromal cell lines, resulted in reduced MM cell viability. In addition, pretreatment of BMMSCs with BMP6 completely abolished their support of MM proliferation. Interestingly, BMP6, in contrast to BMP2 and BMP4, did not induce, but inhibited receptor activator of nuclear kappa-B ligand (RANKL)-dependent osteoclast generation. Collectively, our analyses identify BMP6 as a master regulator that promotes osteogenic differentiation, inhibits RANKL-dependent osteoclastogenesis and can directly induce MM cell death. Therefore, by reshaping the BM microenvironment to become less tumor-supportive, BMP6 represents an attractive candidate for MM treatment. Citation Format: Jiaxian Wang, Thomas Baardemans, Ricardo de Matos Simoes, Olga Dashevsky, Huipin Yuan, Joost D. de Bruijn, Anton C. Martens, Constantine S. Mitsiades, Richard W. Groen. BMP6 overcomes multiple myeloma-induced bone disease by inducing the expression of small leucine-rich proteoglycans [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6374.

The clinical application of stem cell therapies is still limited by the ability to produce defined, differentiated cell populations in large numbers in culture. High throughput screens to identify factors which enhance differentiation to particular lineages and promote expansion of precursors in culture are dependent on the development of sensitive and reproducible assays for screening. Here we describe a bioassay to identify factors with cardiomyogenic activity which enhance the yield of cardiomyocytes from undifferentiated stem cells. The assay is based on a Green Fluorescent Protein (GFP) reporter under the transcriptional control of the 250 bp MLC-2v promoter expressed in pluripotent P19 embryonal carcinoma cells. We show that reporter expression is limited to developing cardiomyocytes and can be used to determine quantitatively the number of ventricular cardiomyocytes formed in cultures under inducing or non-inducing conditions. This assay differs from all others described previously in that it has an easily quantifiable readout, there is negligible background differentiation in the absence of exogenous cardiogenic factors and it is carried out feeder cell-free. Thus, it is entirely independent of competing differentiation inhibitory factors, such as leukemia inhibitory factor. Patch clamp electrophysiology of the GFP-positive cells confirmed their functional ventricular phenotype and indicated that selection on the basis of GFP would provide cells suitable for transplantation.