Extent and clinical significance of the therapy-relevant tight junction protein Claudin 18.2 in pancreatic ductal adenocarcinoma - real-world evidence.

PURPOSE: Pancreatic ductal adenocarcinoma (PDAC) is associated with poor prognosis, wherefore targeted therapies have experienced increasing interest. Zolbetuximab is a novel targeted therapy under investigation in patients with PDAC and targets Claudin 18.2 (CLDN18.2), which is a component of tight junctions and is of significance in various solid tumors. As its role in PDAC is not definitively elucidated, this study aims to clarify the significance of CLDN18.2 expression in PDAC in a real-world setting. METHODS: All patients (n = 309) were recruited at one of the PANCALYZE study centers and received pancreatic resection with curative intention. Paraffin samples were analyzed using an antibody against CLDN18.2, which is known to be comparable to the antibody used by the SPOTLIGHT and GLOW studies. RESULTS: 94 PDACs are positive for CLDN18.2 (30.4 %). Positive CLDN 18.2 expression was associated with significantly better cancer differentiation (p < 0.001). Patients with positive CLDN18.2 expression showed significantly better overall survival when compared to patients with negative expression (median OS: 30 versus 18 months, p = 0.003). Additionally, in multivariable analyses, CLDN18.2 expression was identified as an independent factor for better survival in patients with PDAC (HR = 0.686, 95 %CI = 0.492-0.956, p = 0.026). CONCLUSION: Significant improvement in survival could be demonstrated by adding Zolbetuximab to known chemotherapy regimes in patients with gastro-esophageal junction adenocarcinoma with at least 75 % CLDN18.2 positive cancer cells. Our findings demonstrate, that 30.4 % of the included patients with PDAC would potentially be eligible for therapy with Zolbetuximab in a real-world patient cohort. Results of trials targeting Claudin 18.2 are pending in patients with PDAC.

Surgical and multimodal treatment of metastatic oesophageal cancer: retrospective cohort study.

BACKGROUND: In contrast to the well-established multimodal therapy for localized oesophageal cancer, the metastatic stage is commonly treated only with systemic therapy as current international guidelines recommend. However, evidence suggesting that multimodal therapy including surgery could benefit selected patients with metastasized oesophageal cancer is increasing. The aim of this study was to investigate the survival of patients diagnosed with metastatic oesophageal cancer after different treatment regimens. METHODS: This was a retrospective single-centre study of patients with adenocarcinoma or squamous cell carcinoma of the oesophagus with synchronous or metachronous metastases who underwent Ivor Lewis oesophagectomy between 2010 and 2021. Each patient received an individual treatment for their metastatic burden based on an interdisciplinary tumour board conference. Survival differences between different treatments were assessed using the Kaplan-Meier method, as well as univariable and multivariable Cox regression models. RESULTS: Out of 1791 patients undergoing Ivor Lewis oesophagectomy, 235 patients diagnosed with metastases were included. Of all of the included patients, 42 (17.9%) only underwent surgical resection of their metastatic disease, 37 (15.7%) underwent multimodal therapy including surgery, 78 (33.2%) received chemotherapy alone, 49 (20.9%) received other therapies, and 29 (12.3%) received best supportive care. Patients who underwent resection or multimodal therapy including surgery of their metastatic burden showed superior overall survival compared with chemotherapy alone (median overall survival of 19.0, 18.0, and 11.0 months respectively) (P < 0.001). This was confirmed in subcohorts of patients with metachronous solid-organ metastases and with a single metastasis. In multivariable analyses, resection with or without multimodal therapy was an independent factor for favourable survival. CONCLUSION: Surgical resection could be a feasible treatment option for metastasized oesophageal cancer, improving survival in selected patients. Further prospective randomized studies are needed to confirm these findings and define reliable selection criteria.

Upregulation of the histone γ-H2AX correlates with worse patient survival and basal-like subtype in pancreatic ductal adenocarcinoma.

PURPOSE: Patients with pancreatic ductal adenocarcinoma (PDAC) have yet to experience significant benefits from targeted therapy. Olaparib is currently the only active substance in BRCA-mutated PDACs that successfully influences the DNA repair of carcinoma cells. H2AX belongs to the histone family and is known as a part of the DNA repair system. The inhibition of γ-H2AX could lead to the inhibition of mitotically active tumor cells. Therefore, we aimed to evaluate the predictive value of the γ-H2AX in patients with PDAC. METHODS: All included patients (n = 311) received a pancreatic resection with curative intention in one of our PANCALYZE study centers. Subsequently, they were enrolled in a standardized follow-up protocol. Immunohistochemical stainings for γ-H2AX were conducted on tissue microarrays. RESULTS: Patients exhibiting high levels of γ-H2AX expression experience more frequent R1 resections, indicating advanced tumor stages in this subgroup. Additionally, patients with high γ-H2AX expression demonstrated significantly poorer survival compared to those with low expression (median OS: 15 vs. 25 months, p < 0.001). In multivariate analyses, high γ-H2AX expression could be identified as an independent risk factor for worse patient survival. Moreover, high γ-H2AX expression could be more frequently observed in the more aggressive basal-like subtype. CONCLUSION: γ-H2AX can be characterized as a predictive biomarker for poorer patient survival. Consequently, upcoming clinical trials focused on the efficacy of targeted therapies influencing the DNA repair system and radiotherapy should evaluate γ-H2AX as a potential biomarker for therapy response. Furthermore, γ-H2AX may serve as a viable target for treatment in the future.

Treatment of local recurrence of esophageal cancer following Ivor-Lewis esophagectomy-Experiences of a high-volume center.

PURPOSE: Patients with local recurrence of esophageal cancer have a highly decreased overall survival. There is currently no standardized treatment algorithm for this group. This retrospective cohort study aimed to evaluate the survival of patients with local recurrence, despite receiving individualized treatment options. METHODS: 241 of 1791 patients were diagnosed with a local recurrence following Ivor-Lewis esophagectomy at the University Hospital of Cologne. 59 patients, who were diagnosed only with a local recurrence of adeno- or squamous cell carcinoma and received their individualized therapy regimes at our high-volume center, were included. RESULTS: The study included 52 patients with adenocarcinoma and 7 with squamous cell carcinoma. Among these, 6 patients underwent resection, 19 received solely chemotherapy, 29 received chemoradiotherapy, and 5 were provided with best supportive care. Patients who underwent resection showed a better survival outcome compared to patients without resection (median OS: not reached vs. 15.1 months, p = 0.012). Best supportive care and palliative care were found to be independent risk factors for shorter overall survival compared to curative intended treatment options like local resection or chemoradiotherapy. CONCLUSION: In this study, different treatment strategies for patients with local recurrence of esophageal cancer were depicted. Resection as well as chemoradiotherapy could play a role in selected patients. Further prospective studies are needed to improve the selection of eligible patients.

Copy-number-gain of telomerase reverse transcriptase (hTERT) is associated with an unfavorable prognosis in esophageal adenocarcinoma.

Esophageal adenocarcinoma exhibits one of the highest mortality rates among all cancer entities. Multimodal therapy strategies have improved patients' survival significantly. However, patients in early stages are currently limited to receiving only local therapies, even though some patients within this group showcase short survival periods. Until now, there has been no widely established clinically used biomarker to detect these high-risk patients. Telomerase reverse transcriptase (TERT), a gene encoding a crucial subunit of the telomerase enzyme, plays a significant role in establishing cancer cell immortality and is under suspicion for its potential contribution to tumor progression. Therefore, we aimed to evaluate the clinical relevance of the TERT amplification status. We included 643 patients with esophageal adenocarcinoma, who underwent Ivor-Lewis esophagectomy at the University Hospital of Cologne. The TERT amplification status was characterized using fluorescence in situ hybridization. Clinicopathological values and patients' overall survival were compared between patients with and without TERT amplification. Further sub-cohort analyses were conducted for patients with pT1N0-3 tumor stage. Eighty-One patients (12.6%) exhibited TERT amplification. Patients with amplified TERT showed significantly worse overall survival (median OS: 22.6 vs. 36.8 months, p = 0.009). Interestingly, TERT amplification could be characterized as an independent risk factor for worse overall survival in multivariate analysis in patients with pT1N0-3 tumor stage (HR = 2.440, 95% CI 1.095-5.440, p = 0.029). In this study, we describe the TERT amplification status as an independent risk factor for worse survival in patients diagnosed with esophageal adenocarcinoma at pT1N0-3 tumor stage, encompassing cases involving tumor infiltration of the lamina propria, muscularis mucosae, and/or submucosa. Based on our findings, we put forth the proposition that evaluating the TERT amplification status may serve as a valuable tool in identifying a specific subgroup of patients, namely those with TERT amplification and pT1N0-3 tumor-stage esophageal adenocarcinoma. The patients of this subgroup could potentially benefit from enhanced follow-up protocols, more aggressive treatment approaches, or possible targeted TERT inhibition therapies, all aimed at improving their overall clinical outcomes.

Specific Subtypes of Carcinoma-Associated Fibroblasts Are Correlated with Worse Survival in Resectable Pancreatic Ductal Adenocarcinoma.

PURPOSE: The pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancer entities. Effective therapy options are still lacking. The tumor microenvironment possibly bears further treatment possibilities. This study aimed to describe the expression patterns of four established carcinoma-associated fibroblast (CAFs) markers and their correlation in PDAC tissue samples. METHODS: This project included 321 patients with PDAC who underwent surgery with a curative intent in one of the PANCALYZE study centers. Immunohistochemical stainings for FAP, PDGFR, periostin, and SMA were performed. The expression patterns of each marker were divided into low- and high-expressing CAFs and correlated with patients' survival. RESULTS: Tumors showing SMAhigh-, PeriostinhighSMAhigh-, or PeriostinhighSMAlowPDGFRlowFAPhigh-positive CAFs demonstrated significantly worse survival. Additionally, a high expression of SMA in PDAC tissue samples was shown to be an independent risk factor for worse survival. CONCLUSION: This project identified three subgroups of PDAC with different expression patterns of CAF markers which showed significantly worse survival. This could be the base for the further characterization of the fibroblast subgroups in PDAC and contribute to the development of new targeted therapy options against CAFs.

Cytokeratin 6 identifies basal-like subtypes of pancreatic ductal adenocarcinoma with decreased survival.

PURPOSE: Rising incidence of pancreatic ductal adenocarcinoma (PDAC) bind with insufficient therapy options showcases a great medical challenge. Further biomarkers are required to identify patients, who will benefit from more aggressive therapy. METHODS: 320 patients were included by the PANCALYZE study group. Cytokeratin 6 (CK6) immunohistochemical staining as a putative marker for the basal-like subtype of PDAC was performed. The correlation between CK6 expression patterns and survival data, as well as various markers of the (inflammatory) tumor microenvironment, were analyzed. RESULTS: We divided the study population based on the expression pattern of CK6. Patients with a high CK6 tumor expression had a significantly shorter survival (p = 0.013), confirmed in a multivariate cox regression model. CK6-expression is an independent marker for a decreased overall survival (HR = 1.655, 95% CI 1.158-2.365, p = 0.006). In addition, the CK6-positive tumors showed significantly less plasma cell infiltration and more cancer-associated fibroblasts (CAFs) expressing Periostin and SMA. CONCLUSIONS: CK6 could be considered as an independent biomarker for a shorter overall survival. CK6 is a clinically easily accessible biomarker for the identification of the basal-like subtype of PDAC. Therefore, it could be taken into consideration in deciding for the more aggressive therapy regimes. Prospectively, studies addressing the chemosensitive characteristics of this subtype are required.

Predicting the HER2 status in oesophageal cancer from tissue microarrays using convolutional neural networks.

BACKGROUND: Fast and accurate diagnostics are key for personalised medicine. Particularly in cancer, precise diagnosis is a prerequisite for targeted therapies, which can prolong lives. In this work, we focus on the automatic identification of gastroesophageal adenocarcinoma (GEA) patients that qualify for a personalised therapy targeting epidermal growth factor receptor 2 (HER2). We present a deep-learning method for scoring microscopy images of GEA for the presence of HER2 overexpression. METHODS: Our method is based on convolutional neural networks (CNNs) trained on a rich dataset of 1602 patient samples and tested on an independent set of 307 patient samples. We additionally verified the CNN's generalisation capabilities with an independent dataset with 653 samples from a separate clinical centre. We incorporated an attention mechanism in the network architecture to identify the tissue regions, which are important for the prediction outcome. Our solution allows for direct automated detection of HER2 in immunohistochemistry-stained tissue slides without the need for manual assessment and additional costly in situ hybridisation (ISH) tests. RESULTS: We show accuracy of 0.94, precision of 0.97, and recall of 0.95. Importantly, our approach offers accurate predictions in cases that pathologists cannot resolve and that require additional ISH testing. We confirmed our findings in an independent dataset collected in a different clinical centre. The attention-based CNN exploits morphological information in microscopy images and is superior to a predictive model based on the staining intensity only. CONCLUSIONS: We demonstrate that our approach not only automates an important diagnostic process for GEA patients but also paves the way for the discovery of new morphological features that were previously unknown for GEA pathology.

X-linked inhibitor of apoptosis protein is a prognostic marker for a favorable outcome in three identified subsets in resectable adenocarcinoma of the pancreas.

PURPOSE: Pancreatic ductal adenocarcinoma (PDAC) is currently one of the leading causes of cancer death worldwide. Therefore, building further subgroups as well as enabling individual patient therapy and diagnostics are needed. X-linked inhibitor of apoptosis protein (XIAP) is known to modulate apoptotic and inflammatory pathways. Its expression was found to correlate with patients' survival in other tumor entities. This study aims to examine the role of XIAP in patients with PDAC in relation to the inflammatory microenvironment. METHODS: The PANCALYZE multicenter study group included 257 patients with PDAC. Paraffin-embedded tumor samples were stained immunohistochemically for CD3, CD20, CD38, CD56, CD66b, CD117, and CD163 and XIAP. These stainings were further analyzed digitally with QuPath and survival analyses were done. RESULTS: XIAP-positive patients with T-cell, respectively, neutrophil enriched tumors survived significantly longer compared to XIAP-negative patients (CD3: 37.6 vs. 24.6 months, p = 0.028; CD66b: 34.1 vs. 14.9 months, p = 0.027). Additionally, XIAP-positive patients showed better survival in the lymph node-negative population (48.4 vs. 24.2 months, p = 0.019). Regarding the total population, our findings did not show a correlation between XIAP expression and survival. In multivariate cox regression analyzes XIAP proves to be an independent factor for better survival in the identified subgroups (CD3: p = 0.043; CD66b: p = 0.012, N0: p = 0.040). CONCLUSION: We found XIAP-positive subgroups with significantly better survival in patients with PDAC in T-cell-rich, neutrophil-rich, or lymph node-negative cohorts. This could lead to further individualized cancer treatment with less aggressive therapy protocols for XIAP-positive tumors or more intensive follow-up for XIAP-negative tumors.

IL-17B/RB Activation in Pancreatic Stellate Cells Promotes Pancreatic Cancer Metabolism and Growth.

In pancreatic ductal adenocarcinoma (PDAC), the tumor stroma constitutes most of the cell mass and contributes to therapy resistance and progression. Here we show a hitherto unknown metabolic cooperation between pancreatic stellate cells (PSCs) and tumor cells through Interleukin 17B/Interleukin 17B receptor (IL-17B/IL-17RB) signaling. Tumor-derived IL-17B carrying extracellular vesicles (EVs) activated stromal PSCs and induced the expression of IL-17RB. PSCs increased oxidative phosphorylation while reducing mitochondrial turnover. PSCs activated tumor cells in a feedback loop. Tumor cells subsequently increased oxidative phosphorylation and decreased glycolysis partially via IL-6. In vivo, IL-17RB overexpression in PSCs accelerated tumor growth in a co-injection xenograft mouse model. Our results demonstrate a tumor-to-stroma feedback loop increasing tumor metabolism to accelerate tumor growth under optimal nutritional conditions.

Expression of Immune Checkpoint Regulators IDO, VISTA, LAG3, and TIM3 in Resected Pancreatic Ductal Adenocarcinoma.

Pancreatic cancer features elaborate mechanisms of immune evasion. The potential of new immune molecules was explored to restore the antitumor immune response. If these immune molecules are associated with poor survival, specific drugs could take effect. Here, we analyze the expression of VISTA, LAG3, IDO, and TIM3 on tumor-infiltrating lymphocytes (TILs) and its impact on patient survival. We analyzed 153 pancreatic cancer patients from the prospectively managed database of the multicentered PANCALYZE study. Immunohistochemistry on a tissue microarray assessed VISTA, LAG3, IDO, and TIM3 expression of TILs from the patients undergoing primary resection. Complementarily, we analyzed publicly available transcriptomic data (n = 903). Successful completion of chemotherapy, and lymph node status were independent predictors of survival in the multivariate analysis of the clinicopathologic parameters. Fifteen tumors were exclusively VISTA-positive, thirteen tumors expressed VISTA together with TIM3, and ten tumors expressed VISTA together with IDO. Patients featuring tumors with high numbers of IDO-positive TILs had better patient survival (p = 0.037). VISTA, LAG3, and TIM3 expression did not correlate with survival. The analysis of publicly available data did not show survival differences. Tumors rarely co-express more than two immune molecules at the same time, and VISTA is most frequently co-expressed. Although IDO generally inhibits T-cell proliferation, a high expression of IDO was associated with improved survival. We expect immune checkpoint inhibitors against VISTA, LAG3, and TIM3 to be inefficient in a clinical application.

Interferon-Induced Protein With Multiple Tetratricopeptide Repeats 3 Is Associated With Response to Chemotherapy and Recurrence but Not With Survival.

OBJECTIVES: The interferon-induced protein with multiple tetratricopeptide repeats 3 (IFIT3) seems to be associated with the prognosis in pancreatic cancer. Here we clarify whether the heterogeneity of IFIT3 expression affects previous IFIT3 analysis. METHODS: This retrospective study analyzes pancreatic cancer tissue samples retrieved by surgery from 2 independent patient cohorts. Patients underwent either primary surgery (n = 72) or received neoadjuvant chemotherapy (n = 12). Immunohistochemistry assessed IFIT3 expression and its heterogeneity. Complementarily, we analyzed publicly available transcriptomic data (n = 903). RESULTS: Of the primarily resected tumors, 16.4% were heterogeneous. Patients with IFIT3-negative tumors did not survive longer compared with patients with IFIT3-positive tumors. An analysis of publicly available data confirmed this result. Patients developing lung metastases had the best prognosis (4.8 years) with significantly lower IFIT3 expression compared with liver metastasis (P = 0.0117). Patients receiving neoadjuvant therapy who are IFIT3 negative had a longer disease-free survival (1.2 vs 0.3 years, P = 0.0081). CONCLUSIONS: Low IFIT3 expression is not associated with longer survival. Divergent results from tissue microarray analyses could be explained with tumor heterogeneity. As a single biomarker, IFIT3 is not suitable for predicting disease prognosis. Recurrence of lung metastases and response to neoadjuvant chemotherapy are associated with low IFIT3 expression.

The IL-17A/IL-17RA Axis Is Not Related to Overall Survival and Cancer Stem Cell Modulation in Pancreatic Cancer.

(1) Background: IL-17A accelerates pancreatic intraepithelial neoplasia (PanIN) progression. In this study, we examined whether IL-17A/IL-17RA promotes pancreatic ductal adenocarcinoma (PDAC) aggressiveness in terms of survival and cancer stem cell modulation. (2) Methods: In vitro, the wound-healing assay, the sphere formation assay, and flow cytometry were applied to assess cancer stem cell features. In vivo, pancreatic tumors were induced in C57BL/6 mice using electroporation with oncogenic plasmids (P53-/- R172H; KrasG12V). Anti-IL-17 antibodies were administered as immunotherapy. We analyzed IL-17A/IL-17RA related survival using publicly available transcriptomic data (n = 903). (3) Results: IL-17A/IL-17RA expression was not related to survival in PDAC patients. IL-17A neither induces stem cell markers nor increases sphere formation and cell motility in vitro. Blocking the IL-17A/IL-17RA axis in a murine pancreatic cancer model did not improve the survival of mice, but reduced the tumor burden slightly. (4) Conclusions: IL-17A does not promote stem cell expansion in PDAC cell lines. Blocking IL-17A/IL-17RA signaling does not interfere with pancreatic cancer development and progression and may not be considered as a promising monotherapy for PDAC.

Protocol of the PANCALYZE trial: a multicenter, prospective study investigating the tumor biomarkers CXCR4, SMAD4, SOX9 and IFIT3 in patients with resected pancreatic adenocarcinoma to predict the pattern of recurrence of the disease.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies today with an urgent need for novel therapeutic strategies. Biomarker analysis helps to better understand tumor biology and might emerge as a tool to develop personalized therapies. The aim of the study is to investigate four promising biomarkers to predict the clinical course and particularly the pattern of tumor recurrence after surgical resection. DESIGN: Patients undergoing surgery for PDAC can be enrolled into the PANCALYZE trial. Biomarker expression of CXCR4, SMAD4, SOX9 and IFIT3 will be prospectively assessed by immunohistochemistry and verified by rt.-PCR from tumor and adjacent healthy pancreatic tissue of surgical specimen. Immunohistochemistry expression pattern of all four biomarkers will be combined into a single score. Beginning with the hospital stay clinical data from enrolled patients will be collected and followed. Different adjuvant chemotherapy protocols will be used to create subgroups. The combined biomarker expression score will be correlated with the further clinical course of the patients to test the hypothesis if CXCR4 positive, SMAD4 negative, SOX9 positive, IFIT3 positive tumors will predominantly develop metastatic spread. DISCUSSION: Pancreatic cancer is associated with different patterns of progression requiring personalized therapeutic strategies. Biomarker expression analysis might be a tool to predict the pattern of tumor recurrence and discriminate patients that develop systemic metastatic disease from those with tumors that rather develop local recurrence over time. This data might lead to personalized adjuvant treatment decisions as patients with tumors that stay localized might benefit from adjuvant local therapies like radiochemotherapy as compared to those with systemic recurrence who would benefit exclusively from chemotherapy. Moreover, the pattern of propagation might be a predefined characteristic of pancreatic cancer determined by the genetic signature of the tumor. In the future, biomarker expression analysis could be performed on tumor biopsies to develop personalized therapeutic pathways right after diagnosis of cancer. TRIAL REGISTRATION: German Clinical Trials Register, DRKS00006179 .

Retrograde stapling of a free cervical jejunal interposition graft: a technical innovation and case report.

BACKGROUND: Free jejunal interposition is a useful technique for reconstruction of the cervical esophagus. However, the distal anastomosis between the graft and the remaining thoracic esophagus or a gastric conduit can be technically challenging when located very low in the thoracic aperture. We here describe a modified technique for retrograde stapling of a jejunal graft to a failed gastric conduit using a circular stapler on a delivery system. CASE PRESENTATION: A 56 year-old patient had been referred for esophageal squamous cell carcinoma at 20 cm from the incisors. On day 8 after thoracoabdominal esophagectomy with gastric pull-up, an anastomotic leakage was diagnosed. A proximal-release stent was successfully placed by gastroscopy and the patient was discharged. Two weeks later, an esophagotracheal fistula occurred proximal to the esophageal stent. Cervical esophagostomy was performed with cranial closure of the gastric conduit, which was left in situ within the right hemithorax. Three months later, reconstruction was performed using a free jejunal interposition. The anvil of a circular stapler (Orvil®, Covidien) was placed transabdominally through an endoscopic rendez-vous procedure into the gastric conduit. A free jejunal graft was retrogradely stapled to the proximal end of the conduit. Microvascular anastomoses were performed subsequently. The proximal anastomosis of the conduit was completed manually after reperfusion. CONCLUSIONS: This modified technique allows stapling of a jejunal interposition graft located deep in the thoracic aperture and is therefore a useful method that may help to avoid reconstruction by colonic pull-up and thoracotomy.

Conversion of Th17 into IL-17A(neg) regulatory T cells: a novel mechanism in prolonged allograft survival promoted by mesenchymal stem cell-supported minimized immunosuppressive therapy.

The ultimate goal in transplantation medicine is the promotion of operational tolerance. Although Th cells of the Th17 type have been predominantly associated with rejection of allogeneic solid organ grafts, regulatory T (T(reg)) cells appear to foster operational tolerance. Induced T(reg) and Th17 cells have a higher lineage plasticity than has been recognized thus far. We found that when mesenchymal stem cells (MSCs) were used to induce long-term acceptance of allogeneic heart grafts in mice, the induction of T(reg) cells was preceded by development of a CD11b(hi)Gr1(int) myeloid-derived immunosuppressive cell-mediated Th17 response. Substantial suppression of Foxp3(+) T(reg) cell generation from retinoic acid receptor-related orphan receptor γ(-/-) T cells by MSCs revealed that retinoic acid receptor-related orphan receptor γ is a common factor in the differentiation of T(reg) and Th17 cells. Immunosuppressant mycophenolate mofetil treatment of enriched IL-17A(+) cells from MSC-primed allograft mouse recipients resulted in a reduction of IL-17A production and an increase in the Foxp3(+) T(reg) cell fraction. Furthermore, identification of IL-17A(+) Foxp3(+) double-positive and ex-IL-17-producing IL-17A(neg)Foxp3(+) T cells strongly argues for direct conversion of Th17 cells into T(reg) cells as the underlying mechanism of immune regulation in MSC-mediated allograft survival. The Th17 into T(reg) conversion identified in this study constitutes an important immunological mechanism by which MSC-induced myeloid-derived immunosuppressive cells mediate operational transplant tolerance. The possibility to create T(reg) cell-regulated operational tolerance in the absence of complete immune suppression provides strong clinical implications for cell therapy-assisted minimization protocols.

Rationale and prospects of mesenchymal stem cell therapy for liver transplantation.

PURPOSE OF REVIEW: Despite their potential to supplement the donor organ pool, expanded donor criteria grafts are associated with an elevated risk of graft failure and increased early mortality. Likewise, attempts to promote operational graft tolerance through conventional immunosuppressive therapy have demonstrated significant safety-related drawbacks. Because of their potent regenerative and immunomodulative potential, adjunct mesenchymal stem cell (MSC) therapy represents an innovative approach to both of these clinical problems. RECENT FINDINGS: Recent studies have begun to delineate the benefit and mechanisms of short-term therapy combining MSCs and low-dose immunosuppressive drugs in promoting graft acceptance and potentially regeneration. SUMMARY: The current review presents our rationale for the first-in-man clinical trial in liver transplantation utilizing a mesenchymal cell product (MultiStem, Athersys, Cleveland, Ohio, USA). The long-term objective of this program is to safely minimize the dose of complementary immunosuppressive drugs while achieving long-term allograft survival and operational tolerance. The use of adjunct cellular therapy as a means of reducing long-term pharmacotherapy would represent a major advancement in the field of liver transplantation.

Heart grafts tolerized through third-party multipotent adult progenitor cells can be retransplanted to secondary hosts with no immunosuppression.

Multipotent adult progenitor cells (MAPCs) are an adherent stem cell population that belongs to the mesenchymal-type progenitor cell family. Although MAPCs are emerging as candidate agents for immunomodulation after solid organ transplantation, their value requires further validation in a clinically relevant cell therapy model using an organ donor- and organ recipient-independent, third-party cell product. We report that stable allograft survival can be achieved following third-party MAPC infusion in a rat model of fully allogeneic, heterotopic heart transplantation. Furthermore, long-term accepted heart grafts recovered from MAPC-treated animals can be successfully retransplanted to naïve animals without additional immunosuppression. This prolongation of MAPC-mediated allograft acceptance depends upon a myeloid cell population since depletion of macrophages by clodronate abrogates the tolerogenic MAPC effect. We also show that MAPC-mediated allograft acceptance differs mechanistically from drug-induced tolerance regarding marker gene expression, T regulatory cell induction, retransplantability, and macrophage dependence. MAPC-based immunomodulation represents a promising pathway for clinical immunotherapy that has led us to initiate a phase I clinical trial for testing safety and feasibility of third-party MAPC therapy after liver transplantation.

Mesenchymal Stem Cells in Solid Organ Transplantation (MiSOT) Fourth Meeting: lessons learned from first clinical trials.

The Fourth Expert Meeting of the Mesenchymal Stem Cells in Solid Organ Transplantation (MiSOT) Consortium took place in Barcelona on October 19 and 20, 2012. This meeting focused on the translation of preclinical data into early clinical settings. This position paper highlights the main topics explored on the safety and efficacy of mesenchymal stem cells as a therapeutic agent in solid organ transplantation and emphasizes the issues (proper timing, concomitant immunossupression, source and immunogenicity of mesenchymal stem cells, and oncogenicity) that have been addressed and will be followed up by the MiSOT Consortium in future studies.

Treatment-emergent adverse events after infusion of adherent stem cells: the MiSOT-I score for solid organ transplantation.

BACKGROUND: Cellular therapy after organ transplantation is emerging as an intriguing strategy to achieve dose reduction of classical immunosuppressive pharmacotherapy. Here, we introduce a new scoring system to assess treatment-emergent adverse events (TEAEs) of adherent stem cell therapies in the clinical setting of allogeneic liver transplantation (for example, the MiSOT-I trial Eudract CT: 2009-017795-25). METHODS: The score consists of three independent modalities (set of parameters) that focus on clinically relevant events early after intravenous or intraportal stem cell infusion: pulmonary toxicity, intraportal-infusional toxicity and systemic toxicity. For each modality, values between 0 (no TEAE) and 3 (severe TEAE) were defined. The score was validated retrospectively on a cohort of n=187 recipients of liver allografts not receiving investigational cell therapy between July 2004 and December 2010. These patients represent a control population for further trials. Score values were calculated for days 1, 4, and 10 after liver transplantation. RESULTS: Grade 3 events were most commonly related to the pulmonary system (3.5% of study cohort on day 4). Almost no systemic-related TEAEs were observed during the study period. The relative frequency of grade 3 events never exceeded 5% over all modalities and time points. A subgroup analysis for grade 3 patients provided no descriptors associated with severe TEAEs. CONCLUSION: The MiSOT-I score provides an assessment tool to score specific adverse events that may occur after adherent stem cell therapy in the clinical setting of organ transplantation and is thus a helpful tool to conduct a safety study.