Tumor microenvironment-induced tumor cell plasticity: relationship with hypoxic stress and impact on tumor resistance

The role of tumor interaction with stromal components during carcinogenesis is crucial for the design of efficient cancer treatment approaches. It is widely admitted that tumor hypoxic stress is associated with tumor aggressiveness and thus impacts susceptibility and resistance to different types of treatments. Notable biological processes that hypoxia functions in include its regulation of tumor heterogeneity and plasticity. While hypoxia has been reported as a major player in tumor survival and dissemination regulation, the significance of hypoxia inducible factors in cancer stem cell development remains poorly understood. Several reports indicate that the emergence of cancer stem cells in addition to their phenotype and function within a hypoxic tumor microenvironment impacts cancer progression. In this respect, evidence showed that cancer stem cells are key elements of intratumoral heterogeneity and more importantly are responsible for tumor relapse and escape to treatments. This paper briefly reviews our current knowledge of the interaction between tumor hypoxic stress and its role in stemness acquisition and maintenance. Our review extensively covers the influence of hypoxia on the formation and maintenance of cancer stem cells and discusses the potential of targeting hypoxia-induced alterations in the expression and function of the so far known stem cell markers in cancer therapy approaches. We believe that a better and integrated understanding of the effect of hypoxia on stemness during carcinogenesis might lead to new strategies for exploiting hypoxia-associated pathways and their targeting in the clinical setting in order to overcome resistance mechanisms. More importantly, at the present time, efforts are oriented towards the design of innovative therapeutical approaches that specifically target cancer stem cells.

Abstract OT1-01-03: A phase II multi-center study of BGB324 in combination with pembrolizumab in patients with previously treated, locally advanced and unresectable or metastatic triple negative breast cancer (TNBC) or triple negative inflammatory breast cancer (TN-IBC)

Background. The AXL receptor tyrosine kinase is associated with poor overall survival in breast cancer. AXL signaling is an important regulator of tumor plasticity related to epithelial-to-mesenchymal transition (EMT) and stem cell traits that drive metastasis and drug resistance. Upregulation of AXL has been associated with reduced response to anti-PD-1 therapy. Signaling via AXL is also a key suppressor of the anti-tumor innate immune response, and AXL is expressed on several cells associated with the tumor immune microenvironment. Hence AXL signaling contributes uniquely to both tumor cell intrinsic and microenvironmental anti-tumor immune suppression mechanisms. We show that AXL is required for tumor immune evasion in the 4T1/Balb/C mammary adenocarcinoma model and that blocking AXL signaling with BGB324, a selective clinical-stage small molecule AXL kinase inhibitor, enhanced the effect of immune checkpoint blockade. BGB324 + anti-CTLA-4/anti-PD-1 treated tumors displayed enhanced infiltration of cytotoxic T lymphocytes and Natural Killer cells. Importantly, responding animals rejected orthotopic 4T1 tumor cell re-challenge, demonstrating sustained tumor immunity. These data provided a translational rationale for combining AXL targeted therapy with immune checkpoint inhibitors to enhance anti-cancer immune response.

Study Design. BGBC007 (NCT03184558) is an open-label, single arm, multi-center phase II study designed to assess the anti-tumor activity of BGB324 in combination with pembrolizumab in patients with previously treated, locally advanced and unresectable, or metastatic TNBC or TN-IBC. Secondary objectives include safety and pharmacokinetic profile of BGB324 and pembrolizumab in combination. A single arm, extension of Simon's 2-stage design is employed with an interim and final analysis. Up to 56 evaluable patients will be enrolled. Recruitment will be halted once 28 evaluable patients have been entered to determine the Objective Response Rate (ORR, complete response and partial response). If 5 or fewer responses are observed in up to 28 patients, the trial will be terminated in favor of the null for futility. If 11 or more responses are observed, then the trial will be stopped in favor of the alternative for demonstration of activity. If 6 to 10 patients have an observed response then a further 28 patients may be evaluated. This design provides an overall power of 80.6% to test the stated null and alternative hypothesis. BGB324 will be administered orally, once daily, in a fasted state. Days 1, 2 and 3 of BGB324 administration consists of a 'loading' dose of 400 mg followed by a dose of 200 mg daily. A fixed dose of 200 mg pembrolizumab will be given by intravenous infusion over 30 minutes every 3 weeks. BGB324 and pembrolizumab will be given until disease progression, unacceptable dose toxicity, or until 106 weeks (35 cycles). Efficacy endpoints including ORR, Duration of Response, Progression Free Survival are based on tumor imaging evaluation by RECIST 1.1. Tumor specimens will be taken to assess AXL and PD-L1 expression.

Citation Format: Yule M, Wnuk-Lipinska K, Davidsen K, Blø M, Hodneland L, Engelsen A, Kang J, Lie M, Bougnaud S, Aguilera K, Ahmed L, Rybicka A, Milde Nævdal E, Deyna P, Boniecka A, Straume O, Thiery J-P, Chouaib S, Brekken RA, Gausdal G, Lorens JB. A phase II multi-center study of BGB324 in combination with pembrolizumab in patients with previously treated, locally advanced and unresectable or metastatic triple negative breast cancer (TNBC) or triple negative inflammatory breast cancer (TN-IBC) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT1-01-03.

Resistance to anticancer immunity in cancer patients: potential strategies to reverse resistance

In the 1990s, the application of immunotherapy approaches to target cancer cells resulted in significant clinical responses in patients with advanced malignancies who were refractory to conventional therapies. While early immunotherapeutics were focused on T cell-mediated cytotoxic activity, subsequent efforts were centered on targeted antibody-mediated anticancer therapy. The initial success with antibody therapy encouraged further studies and, consequently, there are now more than 25 FDA-approved antibodies directed against a range of targets. Although both T cell and antibody therapies continue to result in significant clinical responses with minimal toxicity, a significant subset of patients does not respond to immunotherapy and another subset develops resistance following an initial response. This review is focused on describing examples showing that cancer resistance to immunotherapies indeed occurs. In addition, it reviews the mechanisms being used to overcome the resistance to immunotherapies by targeting the tumor cell directly and/or the tumor microenvironment.

Abstract P2-04-08: BGB324, a selective small molecule inhibitor of the receptor tyrosine kinase AXL, enhances immune checkpoint inhibitor efficacy in mammary adenocarcinoma

The AXL receptor tyrosine kinase is associated with poor overall survival in breast cancer. Axl signaling is an important regulator of tumor plasticity related to epithelial-to-mesenchymal transition (EMT) and stem cell traits that drive metastasis and drug resistance. Signaling via AXL is also a key suppressor of the anti-tumor innate immune response. AXL is expressed on several cells associated with the tumor immune microenvironment including natural killer cells, dendritic cells and tumor-associated macrophages. AXL is required for tumor immune evasion in mammary adenocarcinoma models and EMT-mediated resistance to cytotoxic T cell and natural killer (NK)-cell mediated cell killing. Hence AXL signaling contributes uniquely to both tumor cell intrinsic and microenvironmental anti-tumor immune suppression mechanisms in breast cancer. We evaluated whether blocking AXL signaling with BGB324, a selective clinical-stage small molecule Axl kinase inhibitor, enhances the effect of immune checkpoint blockade in the aggressive mammary adenocarcinoma (4T1) syngeneic (Balb/C) mouse modelthat display limited immunogenicity.

Immune therapy with anti-CTLA-4/anti-PD-1 increased AXL and EMT-marker expression in 4T1 tumors, and correlated with lack of response to immune therapy. Combination treatment with BGB324 (50 mg/kg bid) significantly enhanced responsiveness to anti-CTLA-4/anti-PD-1 treatment (10 mg/kg of each, 4 doses) in Balb/C mice bearing established 4T1 tumors. The combination of BGB324 + anti-CTLA-4/anti-PD-1 resulted in durable primary tumor clearance in 23 % of treated mice versus 5.6% obtained with anti-CTLA-4/anti-PD-1 alone (p=0.0157). In a separate study, BGB324 + anti-CTLA-4 treated resulted in 22% long-term primary tumor clearance while no response was observed with anti-CTLA4 treatment alone. The extensive metastasis to the lung, liver and spleen characteristic of this model were concomitantly abrogated in the animals responding to the combination treatment. In addition, BGB324 + anti-CTLA-4/anti-PD-1 treated tumors displayed enhanced infiltration of cytotoxic T lymphocytes (CTLs). Enhanced presence of CTLs was also detected in spleens from animals responding to treatment. BGB324 + anti-CTLA-4/anti-PD-1 treatment increased the number of NK cells, macrophages and polymorphonuclear neutrophils, but decreased the number of mMDSC. Importantly, responding animals rejected orthotopic 4T1 tumor cell re-challenge, demonstrating sustained tumor immunity.

Together with recent results in other tumor types that support a prominent role for AXL in resistance to immune therapy and encouraging results from ongoing clinical trials with BGB324, support combining BGB324 with immune checkpoint inhibitors to improve treatment of breast cancer.

Citation Format: Lorens JB, Lipinska KW, Davidsen K, Blø M, Hodneland L, Engelsen A, Kang J, Lie MK, Bougnaud S, Aguilera K, Ahmed L, Rybicka A, Nævdal EM, Deyna P, Boniecka A, Straume O, Chouaib S, Brekken RA, Gausdal G. BGB324, a selective small molecule inhibitor of the receptor tyrosine kinase AXL, enhances immune checkpoint inhibitor efficacy in mammary adenocarcinoma [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-04-08.

Tumoral CD105 is a novel independent prognostic marker for prognosis in clear-cell renal cell carcinoma

Background:

Angiogenesis is essential for tumour growth and metastasis. There are conflicting reports as to whether microvessel density (MVD) using the endothelial marker CD105 (cluster of differentiation molecule 105) in clear-cell renal cell carcinomas (ccRCC) is associated with prognosis. Recently, CD105 has been described as a RCC cancer stem cell marker.

Methods:

A total of 102 ccRCC were analysed. Representative tumour sections were stained for CD105. Vascularity (endothelial CD105) was quantified by MVD. The immunohistochemistry analysis detected positive (if present) or negative (if absent) CD105 tumoral staining. This retrospective population-based study was evaluated using Kaplan–Meier method, t-test and Cox proportional hazard model.

Results:

We found that the expression of endothelial CD105 (MVD) negatively correlated with nuclear grade (P<0.001), tumour stage (P<0.001) and Leibovitch score (P<0.001), whereas the expression of tumoral CD105 positively correlated with these three clinicopathological factors (P<0.001). In multivariate analysis, tumoral CD105 was found to be an independent predictor of poor overall survival (P=0.002).

Conclusions:

We have shown for the first time that tumoral CD105 is an independent predictive marker for death risk and unfavourable prognosis in patients with ccRCC after curative resection.

In-vivo effect of the combination of tnf and adriamycin against a human breast cell-line expressing the mdr-phenotype

The combined effect of tumor necrosis factor alpha (TNF) and adriamycin (ADR) on tumor cell killing was investigated in vivo. The human breast adenocarcinoma ADR-resistant MDA/ADR cells found to be resistant to in vitro TNF lysis and with an apparent index of resistance to ADR of 23 have been used. Treatment of MDA/ADR subcutaneous tumor bearing mice with PBS, TNF, ADR or the combination of TNF/ADR indicate that the combination of TNF and ADR treatment leads to a significant decrease in tumor growth while treatment with TNF was inactive and treatment with ADR was moderately active. Tumor cells were collected from mice treated with TNF/ADR combination and analysed by PCR for MnSOD and TNF ne expression. No induction of the expression of these genes, known to be involved in the regulation of TNF-induced cell killing, was noted following TNF/ADR combination treatment, suggesting that their products were not involved in the observed resistance.

Immune surveillance of human cancer: if the cytotoxic T-lymphocytes play the music, does the tumoral system call the tune?

Accumulating evidence indicates that the innate and adaptive immune systems participate in the recognition and destruction of cancer cells by a process known as cancer immunosurveillance. Tumor antigen-specific cytotoxic T-lymphocytes (CTL) are the major effectors in the immune response against tumor cells. The identification of tumor-associated antigen (TAA) recognized primarily by CD 8(+) T-lymphocytes has led to the development of several vaccination strategies that induce or potentiate specific immune responses. However, large established tumors, which are associated with the acquisition of tumor resistance to specific lysis, are usually not fully controlled by the immune system. Recently, it has become clear that the immune system not only protects the host against tumor development but also sculpts the immunogenic phenotype of a developing tumor and can favor the emergence of resistant tumor cell variants. Moreover, it has become obvious that the evasion of immunosurveillance by tumor cells is under the control of the tumor microenvironment complexity and plasticity. In this review, we will focus on some new mechanisms associated with the acquisition of tumor resistance to specific lysis during tumor progression, involving genetic instability, structural changes in cytoskeleton, and hypoxic stress. We will also discuss the interaction between CTLs and tumor endothelial cells, a major component of tumor stroma.

[Reactivation of tuberculosis during dual therapy with pegylated interferon and ribavirin for chronic hepatitis C]

Hepatitis C viral infection can be associated with other infectious diseases including viral and bacterial infections such as tuberculosis. Mycobacterium tuberculosis infection may be latent for many years and revealed during an immunodeficiency state. The responsibility of antiviral treatment in the reactivation of tuberculosis is controversial. We report two cases of tuberculous reactivation during bitherapy with pegylated interferon and ribavirin for chronic hepatitis C. A rapid viral response was obtained in both cases. Tuberculous reactivation occurred at 12 and 13 weeks of antiviral treatment, respectively. Tuberculosis involved urinary tract in one patient and lymph nodes in the other. Antituberculous treatment was given and antiviral treatment maintained. The outcome of tuberculosis was favourable and a sustained viral response was obtained for both patients.

[Peritoneal tuberculosis--report of 43 cases]

BACKGROUND

Peritoneal tuberculosis represents 0, 1 to 4% of all forms of tuberculosis.

AIM

The aim of our study is to describe clinical, therapeutic characteristics and the outcome of peritoneal tuberculosis.

METHODS

Retrospective study of all cases of peritoneal tuberculosis diagnosed in gastroenterology B department - Rabta Hospital during a 12 years period (1996 to 2007).

RESULTS

Forty three cases of peritoneal tuberculosis were included: 15 male and 28 female with mean age of 38years (extremes: 16 to 85years). Five patients were cirrhotic. Clinical manifestations were dominated by ascitis (83%). Ascitic fluid were exsudative in 97% of cases and lymphocytic in all cases. The diagnostic was based on coelioscopy with peritoneal biopsy in 26 cases demonstrating caseating granulomatous lesions in 64% of cases. Extra peritoneal tuberculosis was noted in 60, 4% dominated by pleuro-pulmonary localisations. Patients were given antituberculous therapy for a mean duration of 9, 8 months and the outcome was favourable in 93%.

CONCLUSION

Peritoneal tuberculosis is still a medical problem in Tunisia. It is more common in young female. Diagnosis is based on the results of peritoneal biopsies during celioscopy. The outcome is good in most cases after antituberculous treatment.

[Gastrointestinal sarcoidosis]

INTRODUCTION

Sarcoidosis is a granulomatous disorder of unknown cause, characterised by noncaseating granulomas affecting multiple organs. Gastrointestinal tract involvement in sarcoidosis is rare. The stomach, particularly the antrum is the most common extra-hepatic organ to be involved. We report four cases of gastro-intestinal sarcoidosis.

METHODS

Retrospective study of a series of four cases.

RESULTS

All patients had gastric sarcoidosis. It involved the duodenum, ileum and gall bladder in a patient with a history of an acute pancreatitis probably due to sarcoidosis. This patient presented with obstructive intestinal manifestations, weight loss and exsudative enteropathy. Two patients presented with mild abdominal pain and the last patient was admitted for upper gastrointestinal bleeding. The endoscopy was normal in one case and showed an antral congestion in another case. Gastric ulcers were found in the patient with a history of upper gastro-intestinal bleeding. A pseudo-linitic aspect was noticed in the patient with obstructive manifestations. The duodenum and the ileum were normal. This patient had an antrectomy and was treated with corticosteroids. Surgery evidenced a perforated duodenal ulcer, which was obstructed by the gall bladder. The patient with gastrointestinal bleeding received proton pump inhibitor and corticosteroids. These two patients improved gradually. The two other patients recovered spontaneously.

CONCLUSION

The stomach is the most commonly affected organ in gastrointestinal sarcoidosis. Gastric sarcoidosis can mimic a malignant lesion owing to narrowing of the gastric lumen or can be revealed by upper gastrointestinal bleeding. Duodenum, small bowel and colon involvement is uncommon but may be underestimated in the absence of systematic biopsies.

[Budd-Chiari syndrome associated with celiac disease]

The association of Budd-Chiari syndrome and celiac disease is rare and has been reported in only 13 cases. We report a 23-year-old man with celiac disease, treated with gluten-free diet since the age of 16 years. He presented with epigastric pain that was secondary to a Budd-Chiari syndrome. No other cause than celiac disease could be identified.

Seroprevalence of Helicobacter pylori among Tunisian blood donors (outpatients), symptomatic patients and control subjects

OBJECTIVES

Helicobacter pylori is a worldwide infection, although little data are available in the Tunisian population. The aims of our study were to detect the prevalence of H. pylori in a blood-donor population (n=250) and in another population of hospital-consulting patients comprising 87 symptomatic patients and 59 controls, and to determine the factors that influence the prevalence.

MATERIALS AND METHODS

Study subjects answered a standardized questionnaire, and IgG anti-H. pylori and anti-cag were detected by ELISA. In the second population, culture and cagA polymerase chain reaction were performed.

RESULTS

The seroprevalence of H. pylori in blood donors was 64%, and 11% had anti-cag. All patients positive for anti-cag were also positive for anti-H. pylori antibodies. The seroprevalence of H. pylori was 99.3% in the hospital-consulting patients, of whom 55.5% were positive for anti-cag. The difference between the anti-cag and symptomatic patients (66.7%) and controls (39%) was significant. Symptomatic patients had a higher rate of anti-cag (66.7%) compared with the controls (39%) and blood donors (11%).

CONCLUSION

H. pylori seroprevalence in blood donors is low (64%) compared with symptomatic patients (99.3%), and anti-cag was statistically associated with symptomatic patients and pathology. Also, some environmental factors were correlated with H. pylori seroprevalence.

p53 status correlates with histopathological response in patients with soft tissue sarcomas treated using isolated limb perfusion with TNF-alpha and melphalan

BACKGROUND

Recombinant tumor necrosis factor-alpha (TNF-alpha) combined to melphalan is clinically administered through isolated limb perfusion (ILP) for regionally advanced soft tissue sarcomas of the limbs. In preclinical studies, wild-type p53 gene is involved in the regulation of cytotoxic action of TNF-alpha and loss of p53 function contributes to the resistance of tumour cells to TNF-alpha. The relationship between p53 status and response to TNF-alpha and melphalan in patients undergoing ILP is unknown.

PATIENTS AND METHODS

We studied 110 cases of unresectable limbs sarcomas treated by ILP. Immunohistochemistry was carried out using DO7mAb, which reacts with an antigenic determinant from the N-terminal region of both the wild-type and mutant forms of the p53 protein, and PAb1620mAb, which reacts with the 1620 epitope characteristic of the wild-type native conformation of the p53 protein. The immunohistochemistry data were then correlated with various clinical parameters.

RESULTS

P53DO7 was found expressed at high levels in 28 patients, whereas PAb1620 was negative in 20. The tumours with poor histological response to ILP with TNF-alpha and melphalan showed significantly higher levels of p53-mutated protein.

CONCLUSIONS

Our results might be a clue to a role of p53 protein status in TNF-alpha and melphalan response in clinical use.