Prognostic impact of HLA supertype mismatch in single-unit cord blood transplantation

The "human leukocyte antigen (HLA) supertype" is a functional classification of HLA alleles, which was defined by structural features and peptide specificities, and has been reportedly associated with the clinical outcomes of viral infections and autoimmune diseases. Although the disparity in each HLA locus was reported to have no clinical significance in single-unit cord blood transplantation (sCBT), the clinical significance of the HLA supertype in sCBT remains unknown. Therefore, we retrospectively analyzed clinical data of 1603 patients who received sCBT in eight institutes in Japan between 2000 and 2017. Each HLA allele was categorized into 19 supertypes, and the prognostic effect of disparities was then assessed. An HLA-B supertype mismatch was identified as a poor prognostic factor (PFS: hazard ratio [HR] = 1.23, p = 0.00044) and was associated with a higher cumulative incidence (CI) of relapse (HR = 1.24, p = 0.013). However, an HLA-B supertype mismatch was not associated with the CI of acute and chronic graft-versus-host-disease. The multivariate analysis for relapse and PFS showed the significance of an HLA-B supertype mismatch independent of allelic mismatches, and other previously reported prognostic factors. HLA-B supertype-matched grafts should be selected in sCBT.

Co-expression of regulatory B-cell markers, transforming growth factor β and interleukin-10 as a prognostic factor in diffuse large B-cell lymphoma

Regulatory B cells (Bregs) suppress antitumor immunity by producing anti-inflammatory cytokines such as transforming growth factor β (TGF-β) and interleukin-10 (IL-10) and promoting tumor growth. It is unknown whether diffuse large B-cell lymphoma (DLBCL), a common subtype of B-cell malignancy, exhibits characteristics similar to those of Bregs. This study aimed to clarify the features of DLBCLs carrying Breg markers. In 123 DLBCL cases, we evaluated TGF-β and IL-10 expression in tumor biopsy samples using immunohistochemical staining and retrospectively analyzed their clinicopathological characteristics. Fifteen cases (12.2 %) classified as Breg-type DLBCL were positive for both TGF-β and IL-10. Breg-type DLBCL is mainly classified as having activated B cell-like cells of origin. Breg-type DLBCL cases showed significantly worse progression-free survival and overall survival (OS) than other DLBCL cases (P = 0.0016 and P = 0.042, respectively). In multivariate analysis, Breg-type DLBCL significantly affected OS (hazard ratio, 3.13; 95 % confidence interval 1.15-8.55; P = 0.025). Gene expression analysis showed that the expression of follicular dendritic cell-associated genes (FCER2, PIK3CD, FOXO1) was downregulated in Breg-type DLBCLs compared to other DLBCLs. These results suggest that the double expression of Breg markers, TGF-β and IL-10, in tumor cells indicates a poor prognosis in DLBCL patients. Further studies evaluating genomic abnormalities could confirm the characteristics of Breg-type DLBCL.

Impact of a third dose of anti-SARS-CoV-2 vaccine in hematopoietic cell transplant recipients: A Japanese multicenter observational study

This prospective observational study aimed to assess the serological response and safety after the third booster shot of SARS-CoV-2 mRNA vaccines in 292 hematopoietic cell transplant (HCT) recipients. In our patients, mild systemic reactions were present in 10-40% and GVHD aggravation in 1.1%. Overall, clinically relevant response (>250 U/mL) was observed in 93.1% of allogeneic (allo)-HCT recipients and 70.6% of autologous (auto)-HCT recipients, respectively. Of note, detectable antibody response with any titer following the first two doses was a powerful predictor for adequate response after booster shot in both cohorts. For such patients, 98.8% of allo- and 92.3% of auto-HCT recipients obtained clinically relevant response after dose 3. In addition, continued systemic steroid and/or calcineurin inhibitors at the booster shot significantly correlated with serological response. These findings highlighted that booster vaccination efficiently improved serological response without safety concerns and thus recommended for the majority of HCT recipients.

Anti-dsDNA IgE induces IL-4 production from basophils, potentially involved in B-cell differentiation in systemic lupus erythematosus

OBJECTIVES

Recently, the involvement of basophils and IgE-type autoantibodies in the pathogenesis of SLE has been elucidated using mouse models; however, few studies have been conducted in humans. In this study, the role of basophils and anti-double-stranded DNA (dsDNA) IgE in SLE was examined using human samples.

METHODS

The correlation between disease activity and serum levels of anti-dsDNA IgE in SLE was evaluated using enzyme-linked immunosorbent assay. Cytokines produced by IgE-stimulated basophils from healthy subjects were assessed using RNA sequences. The interaction of basophils and B cells to promote B cell differentiation was investigated using a co-culture system. The ability of basophils from patients with SLE with anti-dsDNA IgE to create cytokines that may be involved in B cell differentiation in response to dsDNA was examined using real-time PCR.

RESULTS

Anti-dsDNA IgE levels in the serum of patients with SLE correlated with disease activity. Healthy donor basophils produced IL-3, IL-4 and TGF-β1 after anti-IgE stimulation. Co-culture of B cells with anti-IgE-stimulated basophils increased plasmablasts which were cancelled by neutralizing IL-4. After encountering the antigen, basophils released IL-4 more quickly than follicular helper T cells. Basophils isolated from patients with anti-dsDNA IgE promoted IL-4 expression by adding dsDNA.

CONCLUSIONS

These results suggest that basophils contribute to the pathogenesis of SLE by promoting B cell differentiation via dsDNA-specific IgE in patients similar to the process described in mouse models.

Ferroptosis in the colon epithelial cells as a therapeutic target for ulcerative colitis

BACKGROUND

Ferroptosis, a type of programmed cell death triggered by oxidative stress, was suspected to play a role in ulcerative colitis. Indigo naturalis is highly effective against ulcerative colitis, but its mechanism is unclear. This study found that indigo naturalis treatment suppressed ferroptosis.

METHODS

We analyzed 770 mRNA expressions of patients with ulcerative colitis. Suppression of ferroptosis by indigo naturalis treatment was shown using a cell death assay. Malondialdehyde levels and reactive oxygen species were analyzed in CaCo-2 cells treated with indigo naturalis. Glutathione metabolism was shown by metabolomic analysis. Extraction of the ingredients indigo naturalis from the rectal mucosa was performed using liquid chromatograph-mass spectrometry.

RESULTS

Gene expression profiling showed that indigo naturalis treatment increased antioxidant genes in the mucosa of patients with ulcerative colitis. In vitro analysis showed that nuclear factor erythroid-2-related factor 2-related antioxidant gene expression was upregulated by indigo naturalis. Indigo naturalis treatment rendered cells resistant to ferroptosis. Metabolomic analysis suggested that an increase in reduced glutathione by indigo naturalis. The protein expression of CYP1A1 and GPX4 was increased in the rectum by treatment with indigo naturalis. The main ingredients of indigo naturalis, indirubin and indigo inhibited ferroptosis. Indirubin was detected in the rectal mucosa of patients with ulcerative colitis who were treated with indigo naturalis.

CONCLUSIONS

Suppression of ferroptosis by indigo naturalis in the intestinal epithelium could be therapeutic target for ulcerative colitis. The main active ingredient of indigo naturalis may be indirubin.

Targeting a mitochondrial E3 ubiquitin ligase complex to overcome AML cell-intrinsic Venetoclax resistance

To identify molecules/pathways governing Venetoclax (VEN) sensitivity, we performed genome-wide CRISPR/Cas9 screens using a mouse AML line insensitive to VEN-induced mitochondrial apoptosis. Levels of sgRNAs targeting March5, Ube2j2 or Ube2k significantly decreased upon VEN treatment, suggesting synthetic lethal interaction. Depletion of either Ube2j2 or Ube2k sensitized AML cells to VEN only in the presence of March5, suggesting coordinate function of the E2s Ube2j2 and Ube2k with the E3 ligase March5. We next performed CRISPR screens using March5 knockout cells and identified Noxa as a key March5 substrate. Mechanistically, Bax released from Bcl2 upon VEN treatment was entrapped by Mcl1 and Bcl-XL and failed to induce apoptosis in March5 intact AML cells. By contrast, in March5 knockout cells, liberated Bax did not bind to Mcl1, as Noxa likely occupied Mcl1 BH3-binding grooves and efficiently induced mitochondrial apoptosis. We reveal molecular mechanisms underlying AML cell-intrinsic VEN resistance and suggest a novel means to sensitize AML cells to VEN.

RHAMM marks proliferative subpopulation of human colorectal cancer stem cells

The cancer stem cell (CSC) theory features typically rare self-renewing subpopulation that reconstitute the heterogeneous tumor. Identification of molecules which characterize the feature of CSCs is a key imperative for further understanding of tumor heterogeneity and for the development of novel therapeutic strategies. However, the use of conventional markers of CSCs is still insufficient for the isolation of bona fide CSCs. We investigated organoids which are miniature forms of tumor tissues with reconstructing cellular diversity to identify specific marker to characterize CSCs in heterogeneous tumors. Here, we report that receptor for hyaluronan-mediated motility (RHAMM) expresses in a subpopulation of CD44+ conventional human colorectal CSC fraction. Single-cell transcriptomics of organoids highlighted RHAMM positive proliferative cells that revealed distinct characteristics among the various cell types. Prospectively isolated RHAMM+ CD44+ cells from the human colorectal cancer tissues showed highly proliferative character with self-renewal ability in comparison with the other cancer cells. Furthermore, inhibition of RHAMM strongly suppressed organoids formation in vitro and inhibited the tumor growth in vivo. Our findings suggest that RHAMM is a potential therapeutic target because it is a specific marker of the proliferative subpopulation within the conventional CSC fraction.

Successful pseudo-autologous stem cell transplantation for donor-derived Burkitt lymphoma occurring 9 years after allogeneic transplantation

Donor-derived hematological malignancies have been recognized as rare but serious late complications in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Most cases in the literature were diagnosed as myelodysplastic syndrome or acute leukemia, with very few malignant lymphoma reported. We herein present another case of donor-derived Burkitt lymphoma that occurred 9 years after allo-HSCT under continued administration of immunosuppressants for chronic graft-versus-host disease (GVHD). The patient achieved a partial response after rituximab-combined intensive chemotherapy. To reduce the risk of relapse and to avoid organ toxicities due to repeated chemotherapies, we performed upfront high-dose chemotherapy followed by stem cell rescue using donor-derived CD34⁺ cells, called pseudo-autologous HSCT (pASCT), and adjusted immunosuppressants appropriately. The patient remained disease-free for 23 months after pASCT without exacerbation of cGVHD. Although the observation period has been relatively short and longer follow-up is needed, pASCT may be a feasible option for donor-derived lymphoma even in patients with active cGVHD.

Lymphoma Microenvironment in DLBCL and PTCL-NOS: the key to uncovering heterogeneity and the potential for stratification

Diffuse large B-cell lymphoma (DLBCL) and peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) are the most common subtypes of mature B cell neoplasm and T/NK cell lymphoma, respectively. They share a commonality in that they are, by definition, highly heterogeneous populations. Recent studies are revealing more about the heterogeneity of these diseases, and at the same time, there is an active debate on how to stratify these heterogeneous diseases and make them useful in clinical practice. The various immune cells and non-cellular components surrounding lymphoma cells, i.e., the lymphoma microenvironment, have been the subject of intense research since the late 2000s, and much knowledge has been accumulated over the past decade. As a result, it has become clear that the lymphoma microenvironment, despite its paucity in tissues, significantly impacts the lymphoma pathogenesis and clinical behavior, such as its prognosis and response to therapy. In this article, we review the role of the lymphoma microenvironment in DLBCL and PTCL-NOS, with particular attention given to its impact on the prognosis and stratification.

Prognostic value of pre-transplantation total metabolic tumor volume on 18fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography in relapsed and refractory aggressive lymphoma

Relapsed and refractory aggressive lymphoma have a poor prognosis. High-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (auto-HSCT) is effective in chemosensitive patients. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is among the few options for non-chemosensitive patients. ¹⁸Fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography (¹⁸FDG-PET/CT) is the standard tool for evaluating response to chemotherapy and residual tumor volume. However, accurate assessment of residual tumor volume is not currently being achieved in clinical practice, and its value in prognostic and therapeutic stratification remains unclear. To answer this question, we investigated the efficacy of quantitative indicators, including total metabolic tumor volume (TMTV), in predicting prognosis after auto-HSCT and allo-HSCT. We retrospectively analyzed 39 patients who received auto-HSCT and 28 who received allo-HSCT. In the auto-HSCT group, patients with a higher TMTV had a poor prognosis due to greater risk of relapse. In the allo-HSCT group, patients with a higher TMTV had a lower progression-free survival rate and a significantly higher relapse rate. Neither Deauville score nor other clinical parameters were associated with prognosis in either group. Therefore, pre-transplant TMTV on PET is effective for prognostic prediction and therapeutic decision-making for relapsed or refractory aggressive lymphoma.

Macrophages are primed to transdifferentiate into fibroblasts in malignant ascites and pleural effusions

Cancer-associated fibroblasts (CAFs) play an important role in cancer progression. However, the origin of CAFs remains unclear. This study shows that macrophages in malignant ascites and pleural effusions (cavity fluid-associated macrophages: CAMs) transdifferentiate into fibroblast-like cells. CAMs obtained from gastrointestinal cancer patients were sorted by flow cytometry and cultured in vitro. CD45⁺CD14⁺ CAMs transdifferentiated into CD45^-CD90⁺ fibroblast-like cells that exhibited spindle shapes. Then, cDNA microarray analysis showed that the CD45^-CD90⁺ fibroblast-like cells (macrophage-derived CAFs: MDCAFs) had a fibroblast-specific gene expression signature and produced growth factors for epithelial cell proliferation. Human colon cancer cells transplanted into immunodeficient mice with MDCAFs formed larger tumors than cancer cells alone. Gene ontology analyses showed the involvement of TGFβ signaling and cell-matrix adhesion in MDCAFs, and transdifferentiation of CAMs into MDCAFs was canceled by inhibiting TGFβ and cell adhesion. Furthermore, the acquired genetic alterations in hematopoietic stem cells (HSCs) were shared in CAMs and MDCAFs. Taken together, CAMs could be a source of CAFs and might originate from HSCs. We propose the transdifferentiation process of CAMs into MDCAFs as a new therapeutic target for fibrosis associated with gastrointestinal cancer.

Ustekinumab Improves Active Crohn's Disease by Suppressing the T Helper 17 Pathway

BACKGROUND

Ustekinumab (UST), an antibody targeting the p40 subunit of interleukin (IL)-12 and IL-23, is effective in treating Crohn's disease (CD). To clarify the mechanism of UST, we investigated T-cell differentiation in CD patients treated with UST.

METHODS

Twenty-seven patients with active CD were enrolled in this study. Seventeen patients were treated with UST, and 10 patients were treated with anti-tumor necrosis factor (TNF)-alpha therapy. The changes in the proportions of T-cell subsets after these therapies were analyzed by flow cytometry. Comprehensive gene expression changes in the colonic mucosa were also evaluated.

RESULTS

The frequency of T helper (Th) 17 cells was significantly decreased in the peripheral blood of patients with active CD after UST therapy. Anti-TNF therapy had a minimal effect on Th17 cells but increased the proportion of regulatory T cells. Enrichment analysis showed the expression of genes involved in the Th17 differentiation pathway was downregulated in the colonic mucosa after UST but not anti-TNF therapy. There were no common differentially expressed genes between CD patients treated with UST and anti-TNF therapy, suggesting a clear difference in their mechanism of action.

CONCLUSION

In patients with active CD, UST therapy suppressed Th17 cell differentiation both in the peripheral blood and colonic tissues.

Targeting leukemia-specific dependence on the de novo purine synthesis pathway

Acute myeloid leukemia (AML) is a devastating disease, and clinical outcomes are still far from satisfactory. Here, to identify novel targets for AML therapy, we performed a genome-wide CRISPR/Cas9 screen using AML cell lines, followed by a second screen in vivo. We show that PAICS, an enzyme involved in de novo purine biosynthesis, is a potential target for AML therapy. AML cells expressing shRNA-PAICS exhibited a proliferative disadvantage, indicating a toxic effect of shRNA-PAICS. Treatment of human AML cells with a PAICS inhibitor suppressed their proliferation by inhibiting DNA synthesis and promoting apoptosis and had anti-leukemic effects in AML PDX models. Furthermore, CRISPR/Cas9 screens using AML cells in the presence of the inhibitor revealed genes mediating resistance or synthetic lethal to PAICS inhibition. Our findings identify PAICS as a novel therapeutic target for AML and further define components of de novo purine synthesis pathway and its downstream effectors essential for AML cell survival.

Abstract 1886: Anti -GPRC5D/CD3 T cell-redirecting bispecific antibody with potent in vitro and in vivo antitumor efficacy against multiple myeloma

Background: Although treatment advances over recent decades have significantly improved survival of patients with multiple myeloma, there is still an unmet medical need for more effective treatments. The orphan G protein-coupled receptor, class C group 5 member D (GPRC5D), was previously identified as expressed by mRNA in patients with multiple myeloma with only low expression detected in normal tissues, but confirmation of protein expression remained elusive. In this study, we determined the cell surface expression of GPRC5D on malignant and normal hematological cells. In addition, we evaluated the antitumor activity and mechanism of GPRC5D TRABs in in vitro and in vivo mouse models.

Method & Results: We established specific monoclonal antibodies against human GPRC5D and identified its expression on the surface of malignant cells involved in multiple myeloma, but except for plasma cells and B cells, did not find it at appreciable levels on normal hematopoietic cells and bone marrow progenitors, including hematopoietic stem cells. To investigate whether GPRC5D could be therapeutic target, we generated IgG-based anti-GPRC5D/CD3 bispecific T-cell-redirecting antibodies (GPRC5D TRABs). GPRC5D TRABs induced T cell activation and the killing of a wide variety of GPRC5D expressing tumor cells in vitro. In mouse models with reconstituted human immune cells, GPRC5D TRABs showed strong antitumor efficacy against GPRC5D-positive tumors through the activation of T cells.

Conclusion: These findings suggest that GPRC5D is an antigen specific to multiple myeloma and a potential target of TRAB therapy.

Citation Format: Tatsushi Kodama, Yu Kochi, Waka Nakai, Hideaki Mizuno, Takeshi Baba, Kiyoshi Habu, Noriaki Sawada, Hiroyuki Tsunoda, Takahiro Shima, Kohta Miyawaki, Yoshikane Kikushige, Yasuo Mori, Toshihiro Miyamoto, Takahiro Maeda, Koichi Akashi. Anti -GPRC5D/CD3 T cell-redirecting bispecific antibody with potent in vitro and in vivo antitumor efficacy against multiple myeloma [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 1886.

Long-term follow-up results of a phase II study of dose-adjusted (DA)-EPOCH-R with high-dose methotrexate (HD-MTX) for newly diagnosed stage II-IV CD5-positive diffuse large B-cell lymphoma (CD5+ DLBCL)

7551

Background: CD5+ DLBCL is characterized by a poor prognosis and frequent central nervous system (CNS) relapse after standard immunochemotherapy. In the primary analysis of our multicenter phase II study of DA-EPOCH-R/HD-MTX for newly diagnosed stage II-IV CD5+ DLBCL, the 2-year (yr) progression-free survival (PFS) was 79% and the 2-yr CNS relapse rate was 9% at a median follow-up of 3.1 yrs (Miyazaki, et al. 2020). The aim of this preplanned 5-yr follow-up was to assess PFS, overall survival (OS), the CNS relapse rate, and late toxicity. Methods: A total of 47 patients (pts) with newly diagnosed stage II-IV CD5+ DLBCL between 20-75 yrs old and ECOG PS of 0-3 were enrolled. The treatment included 4 cycles of DA-EPOCH-R followed by 2 cycles of HD-MTX (3.5 g/m2) and 4 additional cycles of DA-EPOCH-R. Intrathecal administration of MTX and/or cytarabine was not allowed. 45 (96%) pts completed the protocol treatment. The data were updated as of December 1, 2020. Results: The median follow-up of alive pts was 6.0 yrs (range, 5.0-7.7). The pts’ characteristics were as follows: age, 37-74 yrs (median, 62); male, 38%; ECOG PS > 1, 4%; stage III/IV, 57%; IPI HI/H, 47%; CNS-IPI high, 21%; and ABC/GCB/unclassified (n = 46), 85%/9%/7%. The 5-yr PFS and OS were 72% (95% CI, 57-83%) and 79% (95% CI, 64-88%), respectively. The 5-yr PFS and OS of pts with CD5+ ABC DLBCL (n = 39) were 72% and 74%, respectively. The 5-yr CNS relapse rate in all 47 pts was 9% (95% CI, 3-22%). There were no CNS relapse events after the primary analysis. Neither grade 3/4 late adverse events nor cardiac events of any grade were observed. Possible second malignancies were recorded in 6 (13%) pts. Among them, one pt who received R-ICE as salvage therapy experienced acute myeloid leukemia. The other 2 pts had colon cancers treated with endoscopic polypectomy/mucosal resection. Conclusions: Both the survival benefit and safety of DA-EPOCH-R/HD-MTX were maintained during a 5-yr follow-up, indicating the excellent efficacy, and safety of this approach as a first-line therapy for CD5+ DLBCL. Clinical trial information: UMIN000008507.

Autoimmune manifestations associated with myelodysplastic syndrome predict a poor prognosis

ABSTRACT

We evaluated the clinical characteristics of autoimmune manifestations (AIMs) associated with myelodysplastic syndrome (MDS) to elucidate whether AIMs impacted MDS outcomes in Japan.This retrospective study including 61 patients who received a new diagnosis of MDS between January 2008 and December 2015 was conducted by the review of electronic medical records for the presence of AIMs within a 1-year period prior to or following the diagnosis of MDS.AIMs were identified in 12 of the 61 (20.0%) patients with MDS. The neutrophil counts and C-reactive protein levels in peripheral blood were significantly elevated in patients with AIMs, and the survival was shorter in those with AIMs compared to those without AIMs. Multivariate analysis demonstrated that the presence of AIMs and higher-risk disease according to the International Prognositic Scoring System (IPSS) were independent risk factors for increased mortality (hazard ratio, 4.76 and 4.79, respectively).This retrospective study revealed that the prognosis was poor in patients with MDS-associated AIMs. The treatment of MDS using the current algorithms is based on prognostic scoring systems such as IPSS. Treatment strategies for patients with MDS-associated AIMs should be reconsidered, even in those with low-risk MDS according to the IPSS.

Type 1 helper T cells generate CXCL9/10-producing T-bet+ effector B cells potentially involved in the pathogenesis of rheumatoid arthritis

Efficacy of B-cell depletion therapy highlights the antibody-independent effector functions of B cells in rheumatoid arthritis (RA). Given type 1 helper T (Th1) cells abundant in synovial fluid (SF) of RA, we have determined whether Th1 cells could generate novel effector B cells. Microarray and qPCR analysis identified CXCL9/10 transcripts as highly expressed genes upon BCR/CD40/IFN-γ stimulation. Activated Th1 cells promoted the generation of CXCL9/10-producing T-bet⁺ B cells. Expression of CXCL9/10 was most pronounced in CXCR3⁺ switched memory B cells. Compared with peripheral blood, SFRA enriched highly activated Th1 cells that coexisted with abundant CXCL9/10-producing T-bet⁺ B cells. Intriguingly, anti-IFN-γ antibody and JAK inhibitors significantly abrogated the generation of CXCL9/10-producing T-bet⁺ B cells. B cell derived CXCL9/10 significantly facilitated the migration of CD4⁺ T cells. These findings suggest that Th1 cells generate the novel CXCL9/10-producing T-bet⁺ effector B cells that could be an ideal pathogenic B cell target for RA therapy.

DA-EPOCH-R combined with high-dose methotrexate in patients with newly diagnosed stage II-IV CD5-positive diffuse large B-cell lymphoma: a single-arm, open-label, phase II study

CD5-positive diffuse large B-cell lymphoma (CD5+ DLBCL) is characterized by poor prognosis and a high frequency of central nervous system relapse after standard immunochemotherapy. We conducted a phase II study to investigate the efficacy and safety of dose-adjusted (DA)- EPOCH-R (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab) combined with high-dose methotrexate (HD-MTX) in newly diagnosed patients with CD5+ DLBCL. Previously untreated patients with stage II to IV CD5+ DLBCL according to the 2008 World Health Organization classification were eligible. Four cycles of DA-EPOCH-R followed by two cycles of HD-MTX and four additional cycles of DAEPOCH- R (DA-EPOCH-R/HD-MTX) were planned as the protocol treatment. The primary end point was 2-year progression-free survival (PFS). Between September 25, 2012, and November 11, 2015, we enrolled 47 evaluable patients. Forty-five (96%) patients completed the protocol treatment. There were no deviations or violations in the DA-EPOCH-R dose levels. The complete response rate was 91%, and the overall response rate was 94%. At a median follow up of 3.1 years (range, 2.0-4.9 years), the 2- year PFS was 79% [95% confidence interval (CI): 64-88]. The 2-year overall survival was 89% (95%CI: 76-95). Toxicity included grade 4 neutropenia in 46 (98%) patients, grade 4 thrombocytopenia 12 (26%) patients, and febrile neutropenia in 31 (66%) patients. No treatment-related death was noted during the study. DA-EPOCH-R/HD-MTX might be a first-line therapy option for stage II-IV CD5+ DLBCL and warrants further investigation. (Trial registered at: UMIN-CTR: UMIN000008507.).

Combination of CD47 and signal-regulatory protein-α constituting the "don't eat me signal" is a prognostic factor in diffuse large B-cell lymphoma

The interaction between CD47 and signal‐regulatory protein‐α (SIRPα) inhibits phagocytosis, thus affecting the clinical outcomes of neoplastic diseases. Although CD47 upregulation is associated with poor prognosis in several malignancies, the effect of SIRPα expression and its coexpression with CD47 remains unclear. This study aimed to investigate the clinicopathologic effect of CD47 and SIRPα expression in diffuse large B‐cell lymphoma (DLBCL). Immunostaining of 120 biopsy samples showed that CD47 is primarily expressed in tumor cells, whereas SIRPα is expressed in nonneoplastic stromal cells, mostly macrophages. CD47^high cases showed higher MYC protein expression and lower MYC translocation. The SIRPα^high cases presented significantly shorter overall survival (OS) and progression‐free survival (PFS) than SIRPα^low cases in the activated B‐cell (ABC) subtype of DLBCL (P = .04 and P = .02, respectively). Both CD47^high and SIRPα^high presented significantly shorter OS and PFS than other cases among all DLBCL patients (P = .01 and P = .004, respectively), and the ABC type (P = .04 and P = .008, respectively) but not the germinal center B‐cell type. Both CD47^high and SIRPα^high yielded a constant independent prognostic value for OS and PFS in multivariate analysis (hazard ratio [HR], 2.93; 95% confidence interval [CI], 1.20‐7.43; P = .02; and HR, 2.87; 95% CI, 1.42‐5.85; P = .003, respectively). To the best of our knowledge, this is the first study to report that combinatorial CD47 and SIRPα expression is a potential independent prognostic factor for DLBCL. Evaluation of CD47 and SIRPα expression could be useful before CD47 blockade therapy.

CCR6+ group 3 innate lymphoid cells accumulate in inflamed joints in rheumatoid arthritis and produce Th17 cytokines

BACKGROUND

Recent studies show that innate lymphoid cells (ILCs) contribute to the development of chronic inflammation and autoimmune disease. In this study, we assessed the ILC function in the development of rheumatoid arthritis (RA).

METHODS

In a mouse model of collagen-induced arthritis (CIA), we identified and purified the ILC subsets in peripheral blood (PB), local lymph nodes (LNs), and joints by fluorescence-activated cell sorting and used quantitative PCR to assess the expression levels of representative cytokines. We also correlated the frequencies of each ILC subset in synovial fluid (SF) with clinical parameters in RA patients.

RESULTS

In the CIA model, the proportion of CCR6+ ILC3s to total ILCs in joints with active inflammation significantly increased relative to non-arthritic joints (median 29.6% vs 16.7%, p = 0.035). CCR6+ ILC3s from mice with arthritis expressed significantly higher levels of IL-17A and IL-22 mRNA than did comparable cells from control mice (p < 0.0001 and p = 0.015). In RA patients, the proportion of CCR6+ ILCs in SF was positively correlated with tender joint counts (TJC) and swollen joint counts (SJC) (ρ=0.689, p = 0.0032 and ρ=0.644, p = 0.0071, respectively). Levels of CC chemokine ligand 20 (CCL20) increased in SF of patients with RA and were significantly correlated with CCR6+ ILC number (ρ=0.697, p = 0.0001).

CONCLUSION

CCR6+ ILC3s may play some roles in the development of RA through the production of IL-17 and IL-22.

Anti-GPRC5D/CD3 Bispecific T-Cell-Redirecting Antibody for the Treatment of Multiple Myeloma

Although treatment advances over recent decades have significantly improved survival of patients with multiple myeloma, there is still an unmet medical need for more effective treatments. In this study, we identified G-protein-coupled receptor family C group 5 member D (GPRC5D) expression on the surface of malignant cells involved in multiple myeloma, but except for plasma cells and B cells, not at appreciable levels on normal hematopoietic cells and bone marrow progenitors, including hematopoietic stem cells. In addition, we constructed IgG-based anti-GPRC5D/CD3 bispecific T-cell-redirecting antibodies (GPRC5D TRAB), which suppressed the tumor growth of GPRC5D-positive myeloma cells through the activation of T cells in vitro and in vivo in xenograft models. Collectively, these findings suggest that GPRC5D is an antigen specific to multiple myeloma and a potential target of TRAB therapy.

Abstract 1157: Single-cell transcriptmoics identifies rhamm positive proliferative cells within human colorectal cancer stem cells

Cancer stem cells (CSCs) can be prospectively isolated based on specific surface marker such as CD44, CD133, LGR5, and CD166, in human colorectal cancer. However, the employment of these CSCs' markers are still insufficient to prospectively isolate the colorectal CSCs. To overcome the cellular heterogeneity of previously reported CSCs fraction, we performed single-cell mRNA sequencing (scRNAseq) of 72 cells within organoid. By conducting scRNAseq, we identified CSCs-like sub-population with high expression of MKI67 and Cyclin families, which was generally expressed in proliferative state of the cells within the organoid. Remarkably, high expression of hyaluronan-mediated motility receptor (HMMR) encoding cell membranous and cytoplasmic molecule, receptor for hyaluronan mediated motility (RHAMM), which was reported to associate with CD44 in hyaluronan binding, was observed in the CSCs-like cells. Prospective isolation of RHAMM+ CD44+ cells, that were sub-population of conventional CSCs fraction, revealed higher organoid- and tumor-forming abilities. Furthermore, comprehensive gene expression analysis also demonstrated the proliferative gene expression within RHAMM+ CD44+ cells. Here, we report RHAMM+ proliferative cells that sub-fraction the conventional CSCs population. &lt;!–EndFragment–&gt;

Citation Format: Michitaka Nakano, Kikushige Yoshikane, Kohta Miyawaki, Shinichi Mizuno, Kyoko Yamaguchi, Takuji Yamauchi, Hiroshi Ariyama, Hitoshi Kusaba, Masafumi Nakamura, Takahiro Maeda, Eishi Baba, Koichi Akashi. Single-cell transcriptmoics identifies rhamm positive proliferative cells within human colorectal cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1157.

Clinicopathological features of HCV-positive splenic diffuse large B cell lymphoma

The hepatitis C virus (HCV) is a single-stranded RNA virus which is thought to be involved in the onset of B cell lymphoma. HCV-positive diffuse large B cell lymphoma (DLBCL) has been reported to clinically manifest in extranodal lesions (e.g., in the liver, spleen, and stomach). Here, we investigated HCV-positive and -negative primary splenic DLBCL (p-spDLBCL) and non-primary splenic DLBCL (ordinary DLBCL). Furthermore, to examine HCV lymphomagenesis, RNA in situ hybridization (ISH), RT-PCR (reverse-transcription polymerase chain reaction), and NS3 immunostaining of HCV viral nonstructural proteins were performed. HCV-positive p-spDLBCL patients presented fewer B symptoms (asymptomatic) and better performance status, with elevated presence of splenic macronodular lesions and more germinal center B cell (GCB) sub-group cases than HCV-negative p-spDLBCL patients. However, HCV-positive ordinary DLBCL patients were found to have more non-GCB sub-group cases than HCV-negative ordinary DLBCL patients. HCV-positive DLBCL patients showed 20.6% (7/34) NS3 positivity, 16.7% (1/6) HCV-RNA in situ positivity, and 22.2% (2/9) detection of HCV-RNA in tumor tissue by RT-PCR. Splenic samples were found to have a higher frequency of HCV detection than lymph node samples, thus suggesting that HCV may be closely related to lymphomagenesis, especially in splenic lymphoma.

Analysis of GNA13 Protein in Follicular Lymphoma and its Association With Poor Prognosis

GNA13 is a G protein involved in modulating tumor proliferative capacity, infiltration, metastasis, and migration. Genomic alteration of GNA13 was frequently observed in follicular lymphoma (FL). In this study, we examined 167 cases of FL by immunostaining of GNA13 using tissue microarray to evaluate the clinical significance. There were 26 GNA13-positive cases (15.6%) and 141 GNA13-negative cases (84.4%). GNA13-positive cases had a higher incidence of early progression of disease for which disease progression was recognized within 2 years compared with GNA13-negative cases (P=0.03). There were no significant differences in other clinicopathologic factors including histological grade, BCL2-IGH translocation, immunohistochemical phenotype, and Follicular Lymphoma International Prognostic Index. In addition, overall survival and progression-free survival were poorer in GNA13-positive cases than in GNA13-negative cases (P=0.009 and 0.005, respectively). In multivariate analysis, GNA13 positivity was found to be a poor prognostic factor for overall survival and progression-free survival. Thus, GNA13 protein expression was an independent prognostic factor and may affect disease progression in FL.

Epithelial-mesenchymal transition is activated in CD44-positive malignant ascites tumor cells of gastrointestinal cancer

Disseminated cancer cells in malignant ascites possess unique properties that differ from primary tumors. However, the biological features of ascites tumor cells (ATC) have not been fully investigated. By analyzing ascites fluid from 65 gastrointestinal cancer patients, the distinguishing characteristics of ATC were identified. High frequency of CD44⁺ cells was observed in ATC using flow cytometry (n = 48). Multiplex quantitative PCR (n = 15) showed higher gene expression of epithelial‐mesenchymal transition (EMT)‐related genes and transforming growth factor beta (TGF‐beta)‐related genes in ATC than in the primary tissues. Immunohistochemistry (n = 10) showed that ATC also had much higher expression of phosphorylated SMAD2 than that in the corresponding primary tissues. TGF‐beta 1 was detected in all cases of malignant ascites by enzyme‐linked immunoassay (n = 38), suggesting the possible interaction of ATC and the ascites microenvironment. In vitro experiments revealed that these ATC properties were maintained by TGF‐beta 1 in cultured ATC(n = 3). Here, we showed that ATCrevealed high frequencies of CD44 and possessed distinct EMT features from primary tissues that were mainly maintained by TGF‐beta 1 in the ascites.

Gastrointestinal Graft-versus-Host Disease Is a Risk Factor for Postengraftment Bloodstream Infection in Allogeneic Hematopoietic Stem Cell Transplant Recipients

Bloodstream infection (BSI) is a well-known cause of morbidity and mortality in allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients. Here, we conducted a retrospective study to assess the morbidity, etiology, risk factors, and outcomes of BSI in the postengraftment period (PE-BSI) after allo-HSCT. Forty-three of 316 patients (13.6%) developed 57 PE-BSI episodes, in which 62 pathogens were isolated: Gram-positive bacteria, gram-negative bacteria, and fungi, respectively, accounted for 54.8%, 35.5%, and 9.7% of the isolates. Multivariate analysis revealed methylprednisolone use for graft-versus-host disease (GVHD) prophylaxis (odds ratio [OR], 6.49; 95% confidence interval [CI], 1.49 to 28.2; P = .013) and acute gastrointestinal GVHD (GI-GVHD) (OR, 8.82; 95% CI, 3.99 to 19.5; P < .0001) as risk factors for developing PE-BSI. This finding suggested that GI-GVHD increases the risk of bacterial translocation and subsequent septicemia. Moreover, among patients with GI-GVHD, insufficient response to corticosteroids, presumably related to an intestinal dysbiosis, significantly correlated with this complication. Patients with PE-BSI presented worse outcome compared with those without (3-year overall survival, 47.0% versus 18.6%; P < .001). Close microbiologic monitoring for BSIs and minimizing intestinal dysbiosis may be crucial to break the vicious cycle between GI-GVHD and bacteremia and to improve transplant outcomes especially in patients who require additional immunosuppressants.

Hepatitis C virus infection is an independent prognostic factor in follicular lymphoma

Hepatitis C virus (HCV) is a single-stranded RNA virus that not only affects hepatocytes, by B cells as well. It is thought that HCV is involved in the onset of B-cell lymphoma. The clinicopathological characteristics of HCV-positive diffuse large B-cell lymphoma (DLBCL) and HCV-positive splenic marginal zone lymphoma (SMZL) are known, but there has been no report on HCV-positive follicular lymphoma (FL). In this study, the clinicopathological characteristics of HCV-positive FL were examined in 263 patients with FL who were classified into a HCV-positive group with HCV antibody and negative groups without one. The number of patients with HCV-positive FL and HCV-negative FL was 10 (3.8%) and 253 (96.2%), respectively. The patients with HCV-positive FL commonly had more than one region of lymphadenopathy, Ann Arbor stage III/IV, hemoglobin <120 g/l, elevated lactate dehydrogenase level, and high-risk categorization of Follicular Lymphoma International Prognostic Index (FLIPI) than in patients with HCV-negative FL. Overall survival and progression-free survival were poorer in patients with HCV-positive FL than in those with HCV-negative FL (p < 0.0001 and 0.006, respectively). Also, multivariate analysis revealed that positive HCV antibody was a poor prognostic factor of OS. In conclusion, HCV-positive FL has unique clinical features and may have a great impact on the overall survival of affected patients.

Integrating genomic alterations in diffuse large B-cell lymphoma identifies new relevant pathways and potential therapeutic targets

Genome studies of diffuse large B-cell lymphoma (DLBCL) have revealed a large number of somatic mutations and structural alterations. However, the clinical significance of these alterations is still not well defined. In this study, we have integrated the analysis of targeted next-generation sequencing of 106 genes and genomic copy number alterations (CNA) in 150 DLBCL. The clinically significant findings were validated in an independent cohort of 111 patients. Germinal center B-cell and activated B-cell DLBCL had a differential profile of mutations, altered pathogenic pathways and CNA. Mutations in genes of the NOTCH pathway and tumor suppressor genes (TP53/CDKN2A), but not individual genes, conferred an unfavorable prognosis, confirmed in the independent validation cohort. A gene expression profiling analysis showed that tumors with NOTCH pathway mutations had a significant modulation of downstream target genes, emphasizing the relevance of this pathway in DLBCL. An in silico drug discovery analysis recognized 69 (46%) cases carrying at least one genomic alteration considered a potential target of drug response according to early clinical trials or preclinical assays in DLBCL or other lymphomas. In conclusion, this study identifies relevant pathways and mutated genes in DLBCL and recognizes potential targets for new intervention strategies.

Most T790M mutations are present on the same EGFR allele as activating mutations in patients with non-small cell lung cancer

OBJECTIVES

The T790M and C797S mutations of the epidermal growth factor receptor gene (EGFR) confer resistance to first- and third-generation EGFR tyrosine kinase inhibitors (TKIs), respectively, in patients with non-small cell lung cancer (NSCLC) harboring activating mutations of EGFR. C797S has been identified in cis or in trans with T790M in tumor specimens from patients who experienced treatment failure with first- and third-generation EGFR-TKIs. The allelic relation between T790M and activating mutations of EGFR has not been well characterized, however. We have now developed a digital polymerase chain reaction (dPCR)-based method for determination of the allelic relation between two types of EGFR mutation (T790M and either C797S or an activating mutation).

MATERIALS AND METHODS

Seven clinical NSCLC specimens and two NSCLC cell lines harboring both an activating mutation and T790M were analyzed with this new method to identify the allelic relation between these EGFR mutations.

RESULTS

The median ratio of the number of alleles positive for both an activating mutation and T790M to the number of T790M-positive alleles was 97.1% (range, 90.0-100%). Confirmatory analysis by next-generation sequencing yielded a corresponding value of 96.7% (range, 89.1-99.5%). Our dPCR method thus reliably identifies the allelic relation between two EGFR mutations in a quantitative manner.

CONCLUSIONS

Almost all T790M mutations were detected in cis with activating mutations of EGFR regardless of the de novo or acquired status of T790M, with cancer cells harboring T790M and activating mutations on the same allele appearing to be selected and enriched during EGFR-TKI treatment.

Functional interleukin-33 receptors are expressed in early progenitor stages of allergy-related granulocytes

Interleukin-33 (IL-33) induces T helper type 2 (Th2) cytokine production and eosinophilia independently of acquired immunity, leading to innate immunity-mediated allergic inflammation. Allergy-related innate myeloid cells such as eosinophils, basophils and mast cells express the IL-33 receptor (IL-33R), but it is still unknown how IL-33 regulates allergic inflammation involving these cells and their progenitors. Here, we revealed that the functional IL-33R was expressed on eosinophil progenitors (EoPs), basophil progenitors (BaPs) and mast cell progenitors (MCPs). In the presence of IL-33, these progenitors did not expand, but produced a high amount of Th2 and pro-inflammatory cytokines such as IL-9, IL-13, IL-1β and IL-6. The amount of cytokines produced by these progenitors was greater than that by mature cells. In vivo, IL-33 stimulated the expansion of EoPs, but it was dependent upon the elevated serum IL-5 that is presumably derived from type 2 innate lymphoid cells that express functional IL-33R. These data collectively suggest that EoPs, BaPs and MCPs are not only the sources of allergy-related granulocytes, but can also be sources of allergy-related cytokines in IL-33-induced inflammation. Because such progenitors can differentiate into mature granulocytes at the site of inflammation, they are potential therapeutic targets in IL-33-related allergic diseases.

Enhanced Reconstitution of Human Erythropoiesis and Thrombopoiesis in an Immunodeficient Mouse Model with Kit(Wv) Mutations

In human-to-mouse xenograft models, reconstitution of human hematopoiesis is usually B-lymphoid dominant. Here we show that the introduction of homozygous Kit(Wv) mutations into C57BL/6.Rag2(null)Il2rg(null) mice with NOD-Sirpa (BRGS) strongly promoted human multi-lineage reconstitution. After xenotransplantation of human CD34(+)CD38(-) cord blood cells, these newly generated C57BL/6.Rag2(null)Il2rg(null)NOD-Sirpa Kit(Wv/Wv) (BRGSK(Wv/Wv)) mice showed significantly higher levels of human cell chimerism and long-term multi-lineage reconstitution compared with BRGS mice. Strikingly, this mouse displayed a robust reconstitution of human erythropoiesis and thrombopoiesis with terminal maturation in the bone marrow. Furthermore, depletion of host macrophages by clodronate administration resulted in the presence of human erythrocytes and platelets in the circulation. Thus, attenuation of mouse KIT signaling greatly enhances the multi-lineage differentiation of human hematopoietic stem and progenitor cells (HSPCs) in mouse bone marrow, presumably by outcompeting mouse HSPCs to occupy suitable microenvironments. The BRGSK(Wv/Wv) mouse model is a useful tool to study human multi-lineage hematopoiesis.

Abstract 1707: Epithelial mesenchymal transition generates cancer stem cells in CD44- colorectal cancer cells

Background: EpCAMhigh CD44+colorectal cancer (CRC) cells are thought to be cancer stem cells. Recently CD44- CRC cells are also suggested to acquire a property of cancer stem cells. Epithelial-mesenchymal transition (EMT) is a possible process of acquisition of cancer stem cell (CSC)-like properties. However, it is unclear whether EMT can be induced in primary human CRC cells.

Patients and Methods: We obtained surgical specimens from 51 CRC patients, and cultured isolated cancer cells on matrigel-coated dish with medium containing growth factors. For induction of EMT, TGF-beta was added into the culture medium. Otherwise, TWIST1 expression was enforced in the cells by using lentiviral transduction. Immunocytochemical analysis, flow cytometric analysis and single cell PCR analysis using 24-genes set containing embryonic stem cell (ES)-related and EMT-related genes were performed. PCR analysis was carried out by C1 single cell auto prep system. CD44- CRC cells with or without enforced expression of TWIST1 were injected into immunodeficient mice.

Results: Fifteen out of 51 samples of cancer cells formed sphere (&gt;50 μm in diameter) after one week culture. The sphere-forming ability was related with clinical stage (Stage 1 and 2;16.7%, Stage 3 and 4;41.3%). Sorted single CD44+ cell had higher sphere-forming ability, compared to CD44- cell. The higher expression of ES- and EMT-related genes was observed in short term culture than in long-term culture, suggesting that differentiation occurred in sphere cells after long-term culture. Single cell PCR analysis revealed that sphere-forming cells were classified into 2 different populations on the basis of primary component analysis. Correlation analysis showed expression of TWIST1 and ES-related genes were correlated. In addition, flow cytometric analysis revealed that sphere forming CD44+ cells gave rise to CD44- cells. These results suggest that CD44+ cells have an ability to reconstruct the heterogeneous population, and EMT is involved in acquisition of CSC-like properties. TGF-beta increased the number of CD44+ cells in CD44- cells, and enhanced sphere-forming ability of CD44- cells. TGF-beta also induced expression of ES-related genes and TWIST1. Enforced expression of TWIST1 induced sphere-forming ability and tumorigenicity in CD44- cells.

Conclusions: We established the culture system to observe the differentiation of CSCs and revealed that EMT might be involved in maintenance of CSCs. We firstly demonstrated that primary CD44- CRC cells undergo EMT and become CD44+ cells by TGF-beta treatment or enforced expression of TWIST1.

Citation Format: Michitaka Nakano, Mamoru Tanaka, Taichi Isobe, Kohta Miyawaki, Yoshikane Kikushige, Hitoshi Kusaba, Shigeo Takaishi, Takashi Ueki, Eishi Baba, Koichi Akashi. Epithelial mesenchymal transition generates cancer stem cells in CD44- colorectal cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1707.

Mogamulizumab Treatment Prior to Allogeneic Hematopoietic Stem Cell Transplantation Induces Severe Acute Graft-versus-Host Disease

Mogamulizumab (MOG), a humanized anti-CC chemokine receptor 4 (CCR4) monoclonal antibody, has recently played an important role in the treatment of adult T cell leukemia/lymphoma (ATLL). Because CCR4 is expressed on normal regulatory T cells as well as on ATLL cells, MOG may accelerate graft-versus-host disease (GVHD) by eradicating regulatory T cells in patients with allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, there is limited information about its safety and efficacy in patients treated with MOG before allo-HSCT. In the present study, 25 patients with ATLL were treated with MOG before allo-HSCT, after which 18 patients (72%) achieved remission. The overall survival and progression-free survival at 1 year post-transplantation were 20.2% (95% CI, 6.0% to 40.3%) and 15.0% (95% CI, 4.3% to 32.0%), respectively. The cumulative incidence of acute GVHD was 64.0% (95% CI, 40.7% to 80.1%) for grade II-IV and 34.7% (95% CI, 15.8% to 54.4%) for grade III-IV. The cumulative incidence of transplantation-related mortality (TRM) was 49.0% (95% CI, 27.0% to 67.8%). Six of 7 patients with acute GVHD grade III-IV died from GVHD, which was the leading cause of death. In particular, a shorter interval from the last administration of MOG to allo-HSCT was associated with more severe GVHD. MOG use before allo-HSCT may decrease the ATLL burden; however, it is associated with an increase in TRM due to severe GVHD. Because MOG is a potent anti-ATLL agent, new treatment protocols should be developed to integrate MOG at suitable doses and timing of administration to minimize unwanted GVHD development.

CD41 marks the initial myelo-erythroid lineage specification in adult mouse hematopoiesis: redefinition of murine common myeloid progenitor

Previous studies have predicted that reciprocal activation of GATA-1 and PU.1 regulates myelo-erythroid versus myelo-lymphoid lineage commitment in early hematopoiesis. Such PU.1-activating myelo-lymphoid progenitors exist within the lymphoid-primed multipotent progenitor (LMPP) population at the primitive Lineage(-) Sca-1(+) c-Kit(+) (LSK) stage. We here show that the counterpart of GATA-1-activating myelo-erythroid progenitor resides also at the LSK stage, expressing CD41 at a high level. Purified CD41(hi) LSK cells showed exceedingly strong and prolonged myelo-erythroid-restricted reconstitution, and primed myelo-erythroid gene expression with a more primitive molecular signature as compared to the original common myeloid progenitor (CMP). The CD41(hi) LSK cells more strongly contributed to emergent and malignant myelopoiesis than LMPPs, and produced the original CMP by downregulating Sca-1 and CD41, suggesting that they are the earliest CMPs. Thus, the hematopoietic developmental map should be revised by integrating the primary branchpoint comprised of the new, isolatable CD41(hi) CMP and the LMPP populations.

M2 Macrophages Enhance Pathological Neovascularization in the Mouse Model of Oxygen-Induced Retinopathy

PURPOSE

To investigate the roles played by M2 macrophages in a mouse model of oxygen-induced retinopathy (OIR).

METHODS

Oxygen-induced retinopathy was induced in C57BL/6J mice by exposing postnatal day seven (P7) pups to 75% oxygen and then returning them to room air at P12. Real-time RT-PCR and immunofluorescence staining were used to assess the levels and distributions of different macrophage markers. Bone marrow-derived M1 and M2 macrophages and mannosylated clodronate liposomes (MCLs) were injected into the vitreous on P12 to examine the effects at P17. M2 macrophages were cocultured with human retinal endothelial cells (HRECs) to examine their effects on proliferation and tube formation.

RESULTS

The results showed that the M2 macrophages, rather than M1 phenotype, were highly expressed in OIR mice. The number of M2 macrophages had increased significantly at P17, and the increase was closely associated with the presence of neovascular tufts in the OIR retinas. Selective depletion of M2 macrophages suppressed the pathological neovascularization and promoted physiological revascularization. In contrast, intravitreal injection of bone marrow-derived M2 macrophages or the culture supernatants promoted pathological neovascularization and inhibited physiological revascularization. In an in vitro coculture system, M2-polarized macrophages significantly promoted proliferation and tube formation of HRECs.

CONCLUSIONS

These results indicated that M2 macrophages, rather than M1, play an important role in promoting retinal pathological neovascularization probably by producing secreted factors. Thus, targeting M2 macrophages could be a potential therapeutic option for inhibiting retinal pathological neovascularization.

Abstract 1520: Plasticity of CD44+ colorectal cancer stem cells depends on TGF-beta-induced epithelial mesenchymal transition (EMT): evidences from ex vivo culture system

Background

EpCAMhigh CD44+ colorectal cancer (CRC) cells are thought to be cancer stem cells. Recently CD44- CRC cells are also suggested to acquire a character of cancer stem cells, but the molecular mechanisms have not been clarified. Epithelial-mesenchymal transition (EMT) is a possible process of cancer cells to acquire stemness. However, it is unclear whether EMT can be induced in primary human CRC.

Patients and Methods

We obtained surgical specimens from 51 CRC patients, and cultured isolated cancer cells on matrigel-coated dish with medium containing several growth factors. For induction of EMT, TGF-beta was added into the culture medium. Immunocytochemistry staining, flow cytometric analysis of the spheroid cells and single cell PCR analysis using 48-gene set containing and Embryonic stem cell (ES)-related genes EMT-related genes were performed.

Results

Cancer cells proliferated and formed sphere (&gt;50 μm in diameter) in 15 out of 51 samples after one week culture. The sphere-forming ability was related with clinical stage (Stage1 and 2:16.7% Stage 3 and 4:41.3%). Sorted single CD44+ cell had higher sphere-forming ability, compared to CD44- cell. The higher expression of ES- and EMT-related genes was observed in sphere-forming cells than in non-sphere forming cells. To confirm the heterogeneity of sphere forming cells derived from sorted single cell, we performed single cell PCR using C1 single cell auto prep system. Cells consisted of a sphere were classified into 2 different population on the basis of primary component analysis. In addition, flow cytometric analysis revealed that sphere forming CD44+ cells gave rise to CD44- cells. These results suggest that CD44+ cells have an ability to reconstruct the heterogeneous population. Next we isolated sphere-forming cells and cultured on the same condition. Isolated sphere-forming CD44+ cells could form sphere with high efficiency. This result suggests that CD44+ cell have a self-renewal ability. Previously, it has been reported that EMT was induced after TGF-beta treatment in cancer cell lines and these cells acquired cancer stem cell properties. In our culture system, we could detect very few CD44+ cells after 8-days culture of CD44- cells, and TGF-beta treatment also increased the number of CD44+ cells. These CD44 expressing cells expressed N-cadherin. Furthermore N-cadherin expressing cells expressed ES-and EMT-related genes. At last, TGF-beta enhanced sphere-forming ability in CD44- cells.

Conclusions

To our knowledge, this is the first report that CD44- cells from primary CRC samples undergo EMT and induced CD44+ cells by TGF-beta treatment. Investigation whether these induced CD44+ cells have cancer stem cell like properties such as tumorigenic potential in immunosuppressive mouse is underway. Also we are going to identify cancer stem cell specific gene expression in our culture system using DNA microarray.

Citation Format: Michitaka Nakano, Hioshi Ariyama, Shingo Tamura, Taichi Isobe, Kohta Miyawaki, Yuta Okumura, Hitoshi Kusaba, Takashi Ueki, Eishi Baba, Koichi Akashi. Plasticity of CD44+ colorectal cancer stem cells depends on TGF-beta-induced epithelial mesenchymal transition (EMT): evidences from ex vivo culture system. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1520. doi:10.1158/1538-7445.AM2015-1520

Downregulation of CXCR4 in Metastasized Breast Cancer Cells and Implication in Their Dormancy

Our understanding of the mechanism of cancer dormancy is emerging, but the underlying mechanisms are not fully understood. Here we analyzed mouse xenograft tumors derived from human breast cancer tissue and the human breast cancer cell line MDA-MB-231 to identify the molecules associated with cancer dormancy. In immunohistological examination using the proliferation marker Ki-67, the tumors included both proliferating and dormant cancer cells, but the number of dormant cells was remarkably increased when they metastasized to the lung. In the gene expression analysis of the orthotopic cancer cells by a single-cell multiplex real-time quantitative reverse transcription PCR followed by flow cytometric analysis, restrained cellular proliferation was associated with downregulation of the chemokine receptor CXCR4. In the immunohistological and flow cytometric analyses, the expression level of CXCR4 in the metastasized cancer cells was decreased compared with that in the cancer cells in orthotopic tumors, although the expression level of the CXCR4 ligand CXCL12 was not reduced in the lung. In addition, the proliferation of the metastasized cancer cells was further decreased by the CXCR4 antagonist administration. In the ex vivo culture of the metastasized cancer cells, the expression level of CXCR4 was increased, and in the xenotransplantation of ex vivo cultured cancer cells, the expression level of CXCR4 was again decreased in the metastasized cancer cells in the lung. These findings indicate that CXCR4 is downregulated in metastasized breast cancer cells and implicated in their dormancy.

Abstract 1947: Plasticity of CD44+ colorectal cancer stem cells depends on TGF-beta-induced epithelial mesenchymal transition(EMT): Evidences from an ex vivo culture

Background

EpCAMhigh CD44+ colorectal cancer (CRC) cells are thought to be cancer stem cells. Recently CD44- CRC cells are also suggested to gain a character of cancer stem cells, but the molecular mechanisms have not been clarified. Epithelial-mesenchymal transition (EMT), which is observed in several caner cell lines, could be a possible process of cancer cells to obtain stemness. However, whether primary human CRC cells underwent EMT has not been proven.

Patients and Methods

We obtained surgical specimens of 30 cases of advanced CRC, and cultured isolated primary cancer cells in matrigel-based medium containing several growth factors. For induction of EMT, TGF-beta was added into the culture of CD44+ and CD44- cells. Immunocytochemistry staining and flow cytometry of the spheroid cells and single cell PCR analysis of the cultured cells using 48-gene set that included EMT-related genes (BioMark HD System:Fluidigm Corporation) were performed.

Results

Cancer cells grew spherically (50 μm&gt; diameter) in 20 out of 30 samples after a week culture of whole isolated cancer cells. The sphere mostly consisted of CD44+ cells, and non-sphere forming single cells were CD44-negative. Isolated CD44+ cells from primary samples gave rise to CD44+ and CD44- cells in a week culture. Interestingly, 10% of CD44- cell from primary samples also expressed CD44. Similar to the previous findings of cell lines that TGF-beta-induced EMT could convert CD44- cells into CD44+ cancer initiating cells, increased number of CD44+ cells appeared from primary CD44- cells cultured with TGF-beta. In this culture, N-cadherin+ cells increased time-dependent manner and most of this N-cadherin expressing cells co-expressed CD44. In single cell PCR analysis, increased expression of EMT-related genes, vimentin and TWIST1, were preferentially detected in CD44+N-Cadherin+ cells.

Conclusions

To our knowledge, this is the first report that CD44- cells from primary samples undergo EMT and convert into CD44+ cells by TGF-β treatment. Investigation whether these CD44+ converted cells have cancer stem cell properties such as tumorigenic potential in immunodeficient mouse, self renewing ability and drug resistance is underway.

Citation Format: Michitaka Nakano, Hiroshi Ariyama, Shingo Tamura, Taichi Isobe, Kohta Miyawaki, Yuta Okumura, Hitoshi Kusaba, Eishi Baba, Koichi Akashi. Plasticity of CD44+ colorectal cancer stem cells depends on TGF-beta-induced epithelial mesenchymal transition(EMT): Evidences from an ex vivo culture. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1947. doi:10.1158/1538-7445.AM2014-1947