Hajime Kashima

Cancer-Associated Fibroblasts Affect Intratumoral CD8+ and FoxP3+ T Cells Via IL6 in the Tumor Microenvironment

Purpose: Cancer-associated fibroblasts (CAFs) in the tumor microenvironment (TME) play a central role in tumor progression. We investigated whether CAFs can regulate tumor-infiltrating lymphocytes (TILs) and their role in tumor immunosuppression. Experimental Design: A total of 140 cases of esophageal cancer were analyzed for CAFs and CD8+ or forkhead box protein 3 (FoxP3+) TILs by IHC. We analyzed cytokines using murine or human fibroblasts and cancer cells. Murine-derived fibroblasts and cancer cells were also inoculated into BALB/c or BALB/c-nu/nu mice and the tumors treated with recombinant IL6 or anti-IL6 antibody. Results: CD8+ TILs and CAFs were negatively correlated in intratumoral tissues (P < 0.001), whereas FoxP3+ TILs were positively correlated (P < 0.001) in esophageal cancers. Cocultured Colon26 cancer cells and fibroblasts resulted in accelerated tumor growth in BALB/c mice, along with decreased CD8+ and increased FoxP3+ TILs, compared with cancer cells alone. In vitro, IL6 was highly secreted in both murine and human cancer cell/fibroblast cocultures. IL6 significantly increased Colon26 tumor growth in immune-competent BALB/c (P < 0.001) with fewer CD8+ TILs than untreated tumors (P < 0.001), whereas no difference in BALB/c-nu/nu mice. In contrast, FoxP3+ TILs increased in IL6-treated tumors (P < 0.001). IL6 antibody blockade of tumors cocultured with fibroblasts resulted not only in regression of tumor growth but also in the accumulation of CD8+ TILs in intratumoral tissues. Conclusions: CAFs regulate immunosuppressive TIL populations in the TME via IL6. IL6 blockade, or targeting CAFs, may improve preexisting tumor immunity and enhance the efficacy of conventional immunotherapies. Clin Cancer Res; 24(19); 4820–33. ©2018 AACR.

Iron depletion is a novel therapeutic strategy to target cancer stem cells

Adequate iron levels are essential for human health. However, iron overload can act as catalyst for the formation of free radicals, which may cause cancer. Cancer stem cells (CSCs), which maintain the hallmark stem cell characteristics of self-renewal and differentiation capacity, have been proposed as a driving force of tumorigenesis and metastases. In the present study, we investigated the role of iron in the proliferation and stemness of CSCs, using the miPS-LLCcm cell model. Although the anti-cancer agents fluorouracil and cisplatin suppressed the proliferation of miPS-LLCcm cells, these drugs did not alter the expression of stemness markers, including Nanog, SOX2, c-Myc, Oct3/4 and Klf4. In contrast, iron depletion by the iron chelators deferasirox and deferoxamine suppressed the proliferation of miPS-LLCcm cells and the expression of stemness markers. In an allograft model, deferasirox inhibited the growth of miPS-LLCcm implants, which was associated with decreased expression of Nanog and Sox2. Altogether, iron appears to be crucial for the proliferation and maintenance of stemness of CSCs, and iron depletion may be a novel therapeutic strategy to target CSCs.

Abstract 4160: Prognostic correlation of tumor-infiltrating lymphocytes (TILs) and cancer associated fibroblasts (CAFs) in patients with human esophageal carcinoma

Backgrounds: Cancer associated fibroblasts (CAFs) are thought to play an essential role in cancer invasion, migration, metastasis, and tumor immunosuppression. However, there has been still a little evidence of the correlation of tumor immunosuppression and CAFs in human esophageal carcinoma. The other hand, as like rising of PD-1 antibody targeting therapy to tumor immunosuppression have been shown dramatic cure responses in melanoma and now ongoing to other malignancies. Tumor-infiltrating lymphocytes (TILs) are considered typically to represent a host immune response against carcinoma. In many types of tumors TILs have been shown their strong correlation to patient9s clinicopathological features. In this study, we evaluated the prognostic correlation of CAFs and TILs, which are classified respectively in tumor-associated CD8+ cytotoxic T lymphocytes (CTL) and FoxP3+ regulatory T cells (Treg) in surgically resected esophageal carcinoma. Materials and methods: Total 58 cases with esophageal carcinoma in our institution were evaluated for the presence of CAFs and TILs by immunohistochemistry. TILs of CTL and Treg were calculated each in the intratumoral and the peripheral tissues, and the cutoff for subgroups was defined at the median value. CAFs were defined as fibroblasts expressing alpha smooth muscle actin (α-SMA), and evaluated with the α-SMA scoring by using “Area Index”, which is calculated by imageJ. TILs and CAFs were assessed for the associations with pathological invasion depth (pT), lymph node metastases (pN), histological types, and disease-free survival (DFS) or overall survival (OS). Result: In intratumoral tissues, Treg was significantly associated with advanced T stages, and Treg and a CTL/Treg ratio were associated with lymph node metastasis. Higher CTL, higher CTL/Treg ratio and lower Treg were significantly associated with improved DFS and OS in univariate analysis. Furthermore, multivariate analysis demonstrated selected higher CTL as an independent prognostic factor (P = 0.010). On the other hand, in peripheral tissues, CTL, Treg, and CTL/Treg ratio were not correlated with clinicopathological factors or the any prognosis. Additionally the overexpression of CAFs was strongly associated with poor prognosis (P = 0.002) and the “Area Index” of α-SMA was inversely correlated with the CTL and CTL/Treg ratio in intratumoral tissues (P = 0.029, 0.017). It suggests that CAFs accumulation in tumor tissue is correlated to status of intratumoral immunesuppression. Conclusion: The CTL in intratumoral tissues are independent prognostic factors, and are considered to play an essential role in tumor immunity. Our results demonstrate that CAFs are significant correlation of immunosuppression in esophageal carcinoma. In the future, targeting CAFs therapy itself might improve tumor immunosuppression, and there is possibility to prolong a prognosis. Citation Format: Takuya Kato, Kazuhiro Noma, Yuki Katsura, Hajime Kashima, Takayuki Ninomiya, Toshiaki Ohara, Hiroshi Tazawa, Shunsuke Kagawa, Yasuhiro Shirakawa, Toshiyoshi Fujiwara. Prognostic correlation of tumor-infiltrating lymphocytes (TILs) and cancer associated fibroblasts (CAFs) in patients with human esophageal carcinoma. [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 4160.

Cancer-associated fibroblasts (CAFs) promote the lymph node metastasis of esophageal squamous cell carcinoma: Cancer-associated fibroblasts (CAFs) promote the lymph node metastasis of esophageal squamous cell carcinoma

Lymph node metastasis is a pathognomonic feature of spreading tumors, and overcoming metastasis is a challenge in attaining more favorable clinical outcomes. Esophageal cancer is an aggressive tumor for which lymph node metastasis is a strong poor prognostic factor, and the tumor microenvironment (TME), and cancer‐associated fibroblasts (CAFs) in particular, has been implicated in esophageal cancer progression. CAFs play a central role in the TME and have been reported to provide suitable conditions for the progression of esophageal cancer, similar to their role in other malignancies. However, little is known concerning the relevance of CAFs to the lymph node metastasis of esophageal cancer. Here, we used clinical samples of esophageal cancer to reveal that CAFs promote lymph node metastasis and subsequently verified the intercellular relationships in vitro and in vivo using an orthotopic metastatic mouse model. In the analysis of clinical samples, FAP+ CAFs were strongly associated with lymph node metastasis rather than with other prognostic factors. Furthermore, CAFs affected the ability of esophageal cancer cells to acquire metastatic phenotypes in vitro; this finding was confirmed by data from an in vivo orthotopic metastatic mouse model showing that the number of lymph node metastases increased upon injection of cocultured cancer cells and CAFs. In summary, we verified in vitro and in vivo that the accumulation of CAFs enhances the lymph node metastasis of ESCC. Our data suggest that CAF targeted therapy can reduce lymph node metastasis and improve the prognosis of patients with esophageal cancer in the future.

Abstract 5905: Cancer associated fibroblasts promote tumor metastasis coexisting with cancer cells in blood circulation

Background: Cancer associated fibroblasts (CAFs) are activated fibroblasts and an important player in the tumor microenvironment. Their activity promotes cancer cell proliferation, migration, and invasion, and metastasis. The most prognostic factor in tumor progression is metastasis. Cancer metastasis is a multi-step process that tumor cells detach from primary site, survive in the bloodstream, and seed in target organ. Although previous studies have focused on the interaction between CAFs and cancer cells in primary tumor site, the roles of CAFs in blood circulation remain largely unknown. We investigated the effect of CAFs coexisting with cancer cells in bloodstream on tumor metastasis in vivo mouse model, and also examined the effect of CAFs in subcutaneous tumor. Methods: We used female BALB/c-nu/nu mice and BALB/c mice in the experiments. Cancer cells were mouse mammary carcinoma cell lines 4T1 transfected with luciferase, colon cancer cell lines Colon 26 transfected with luciferase. Fibroblast cell lines were mouse embryonic fibroblast MEF and NIH-3T3. In venous injection mouse model, we injected 1 × 10 6 cancer cells alone or the same number of cancer and fibroblast co-cultured together. When we injected cancer cells transfected with luciferase, the mice were subjected to in vivo imaging system (IVIS) and measured luminescence intensity of metastatic sites. We have also harvested lung and compared its weight and metastatic nodule under microscopy. Furthermore, in subcutaneous tumor metastatic mouse model, cancer cells alone or mixed with cancer cells and CAFs were subcutaneously inoculated into the mice. Results: In the group of mice injected with cancer cells and fibroblasts, luminescent intensity of each lungs were higher than cancer cell alone. Harvested lung weight and the number of metastatic nodules were also higher in the group with cancer cells and fibroblasts.In subcutaneous model, mice inoculated with cancer cells and fibroblast had much more metastatic sites than cancer cells alone. Conclusions: Our data indicate that CAFs promote tumor metastasis by stimulating cancer cells in blood circulation, as well as in primary tumor site.These findings suggest that CAFs in both bloodstream and primary site could be a promising therapeutic target. CAF-targeted therapy could reduce tumor metastasis and improve the prognosis of cancer patients. Citation Format: Hajime Kashima, Kazuhiro Noma, Hiroaki Sato, Yuki Katsura, Takuya Kato, Toshiaki Ohara, Hiroshi Tazawa, Yasuhiro Shirakawa, Toshiyoshi Fujiwara. Cancer associated fibroblasts promote tumor metastasis coexisting with cancer cells in blood circulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5905. doi:10.1158/1538-7445.AM2017-5905

Abstract 1560: Correlation of FAP(fibroblast activation protein)-expressing cancer associated fibroblasts (CAFs) and tumor metastasis in esophageal carcinoma

Background: The tumor and its microenvironment have dynamic interactions and signaling that strongly affect tumor progression. Cancer associated fibroblasts (CAFs) are activated fibroblasts and thought to be an important player in the tumor microenvironment. Although there are several indicators of CAF, fibroblast activation protein (FAP) is unique in its selectivity for CAFs in comparison with other markers. The aim of this study is to investigate CAFs expressing FAP and its relationship to cancer metastasis in esophageal cancer. Methods: Sections of paraffin-embedded resected primary human esophageal cancer specimens from 2008 through 2010 in Okayama University hospital were stained with antibody directed against FAP. Overall percentage of stromal FAP staining of the primary tumor was assessed semi-quantitatively (0, 1, 2, 3, 4, 5) and staining intensity was also graded (none, weak, intermediate, strong). Survival time and time to recurrence data were analyzed using Kaplan-Meier plots, log-rank tests, and Cox proportional hazards models. Results: 49 patients with resected specimens were available for study with 26 (53.1%) stage I, 8 (16.3%) stage II, 14 (28.6%) stage III, and 1 (2.0%) stage IV patients. All patients were divided to 2 groups, FAP high group and FAP low group, which are 25 patients (51%) and 24 (49%) respectively. The cutoff for subgroups was defined at the median value. FAP (immune) expression at tumoral stroma was a significant predictive factor for lymph node metastasis (p Conclusions: Our clinicopathological analysis indicates that patients whose esophageal carcinoma have high levels of stromal FAP expression are more likely to have an aggressive disease progression and a potential development of metastases and recurrence. Although therapeutic strategies targeting the tumor cells have been generally inadequate in esophageal carcinomas yet, here we announce that a stroma-targeted therapy should be considered. Now we are ongoing to evaluate metastatic potential of CAFs in vitro and vivo, in order to elucidate the function of FAP expressing CAFs and, in future to establish a novel therapeutic strategy. Citation Format: Hajime Kashima, Kazuhiro Noma, Yuki Katsura, Takuya Kato, Ryoichi Katsube, Takayuki Ninomiya, Toshiaki Ohara, Hiroshi Tazawa, Shunsuke Kagawa, Yasuhiro Shirakawa, Toshiyoshi Fujiwara. Correlation of FAP(fibroblast activation protein)-expressing cancer associated fibroblasts (CAFs) and tumor metastasis in esophageal carcinoma. [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 1560.

Abstract 4243: Iron control is a novel therapeutic target of cancer stem cells

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Background: Iron overload is known to cause cancer in animal models. Several studies have shown that iron deprivation treatment has a strong anti-cancer effect. However, it is unclear whether iron deprivation treatment suppresses cancer stem cells or not. A cancer stem cell model, miPS-LLCcm, was recently epigenetically established from murine induced pluripotent stem cells (miPS cells) in Okayama University. In this model, the green fluorescent protein (GFP) and the puromycin resistant gene were inserted into the 59-bp untranslated region of the Nanog gene of miPS cells. By this procedure, undifferentiated cancer progenitor cells are recognized as GFP positive cells. We then examined the iron dependency of these cancer stem cells both in in vitro and in vivo studies and we used this model to examine the possibility of cancer stem cells by iron deprivation. Materials and Methods: In in vitro studies, the miPS-LLCcm cells were used as cancer stem cells and colon26 and 4T1 cells were used as differentiated murine cancer cells. Puromycin was used to purify the cancer stem cells before seeding of the miPS-LLCcm cells. The dependency on iron for cell proliferation was examined following transferrin addition. Transferrin (Holo) was used to simulate an iron rich condition. Iron free medium and the iron chelators, Deferasirox and Deferoxamine, plus 1% fetal bovine serum (FBS) were used to simulate iron depletion conditions. Cell proliferation assays and flow cytometric analyses were performed 48 hours after adjustment of the iron concentration level. In in vivo studies, an iron depleted diet was used to simulate iron depleted conditions. Nude mice were divided into normal diet and iron depleted diet groups. The mice were fed with these diets for three weeks and then a suspension of miPS-LLCcm cells was injected into the backs of the nude mice. Tumor size was measured and the tumors were immunohistologically examined. Results: In the in vitro studies, transferrin strongly promoted the proliferation of cancer stem cells under iron depletion conditions compared to no transferrin(p<0.001). However, transferrin did not promote the proliferation of the differentiated 4T1 and colon26 cancer cells. The number of GFP-expressing cancer stem cells decreased as the iron concentration was decreased. In the vivo studies, iron depletion significantly suppressed the tumor growth of the cancer stem cells (p<0.05). Immunohistological analysis indicated that Nanog expression was also decreased in the tumors of the iron depletion diet group. Conclusions: Iron is a key element for the proliferation and differentiation of cancer stem cells. Iron controlling therapy including iron chelators is a novel therapeutic target of cancer stem cells. Citation Format: Takayuki Ninomiya, Toshiaki Ohara, Hajime Kashima, Ryoichi Katsube, Kazuhiro Noma, Yasuko Tomono, Akifumi Mizutani, Tomonari Kasai, Masaharu Seno, Shinji Kuroda, Hiroyuki Kishimoto, Hiroshi Tazawa, Yasuhiro Shirakawa, Shunsuke Kagawa, Toshiyoshi Fujiwara. Iron control is a novel therapeutic target of cancer stem cells. [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 4243. doi:10.1158/1538-7445.AM2015-4243

Abstract CT123: Phase I/II trial of endoscopic intratumoral administration of OBP-301, a novel telomerase-specific oncolytic virus, with radiation in elderly esophageal cancer patients

Background: Telomerase activation is considered to be a critical step in carcinogenesis and its activity is closely correlated with human telomerase reverse transcriptase (hTERT) expression. We constructed an adenovirus 5 vector OBP-301 (Telomelysin), in which the hTERT promoter drives expression of E1A and E1B genes. OBP-301 causes selective replication and lysis of a variety of human cancer cells, and also inhibits the repair of radiation-induced DNA double-strand breaks, leading to radiosensitization. A phase I study has confirmed the safety and biological activity of intratumoral administration of OBP-301 alone in patients with advanced solid tumors in the United States. To further determine the feasibility, efficacy, and pharmacokinetics of OBP-301 in combination with radiotherapy, a phase I/II study was designed in elderly patients with esophageal cancer. Methods: Patients with histologically confirmed esophageal cancer who were not eligible for standard treatments such as surgery and chemotherapy were enrolled into this study (UMIN000010158). Study treatment consisted of intratumoral needle injections of OBP-301 on days 1, 18, and 32 of treatment. Radiation therapy was administered concurrently over 6 weeks, beginning on day 4, to a total of 60 Gy. Virus administration was performed by intratumoral injection of the primary or metastatic tumor through a flexible endoscope. OBP-301 doses will be escalated initially in cohorts of two for the first 9 patients (1 × 10e10 and 1 × 10e11 virus particles [vp]). Six subsequent patients will receive the highest dose (1 × 10e12 vp). Virus shedding will be monitored in the saliva, sputum, urine, and plasma by a quantitative DNA-PCR assay. Results: Six patients were enrolled and treated in the cohort with 1 × 10e10 vp of OBP-301. The patients comprised 4 males and 2 females, with median age of 83.5 years (range, 68 to 92 years). Only two patients had prior platinum-based chemotherapy. By November 2014, 3 patients completed treatment. All patients developed a transient, self-limited lymphopenia. A 92-year-old female showed a grade 4 lymphopenia classified as being possibly related to the treatment, although it recovered by the interruption of radiation. No other virus-related toxicities were noted. Objective responses were complete response (CR) in 2 patients and partial response (PR) with tumor regression, resulting in reopening of the esophagus, in 1 patient. Pathological analysis in biopsy specimens obtained from completely responded patients demonstrated no viable malignant cells for 3 to 5 months after the treatment completion. Conclusions: Multiple courses of endoscopic OBP-301 injection in combination with locoregional radiotherapy were feasible and well tolerated in elderly patients with esophageal cancer, and appeared to provide clinical benefit. Citation Format: Shunsuke Tanabe, Hiroshi Tazawa, Shunsuke Kagawa, Kazuhiro Noma, Kiyoto Takehara, Takeshi Koujima, Hajime Kashima, Takuya Kato, Shinji Kuroda, Satoru Kikuchi, Yasuhiro Shirakawa, Toshiyoshi Fujiwara. Phase I/II trial of endoscopic intratumoral administration of OBP-301, a novel telomerase-specific oncolytic virus, with radiation in elderly esophageal cancer patients. [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 CT123. doi:10.1158/1538-7445.AM2015-CT123