Engineering tumor-colonizing E. coli Nissle 1917 for detection and treatment of colorectal neoplasia.

Bioengineered probiotics enable new opportunities to improve colorectal cancer (CRC) screening, prevention and treatment. Here, first, we demonstrate selective colonization of colorectal adenomas after oral delivery of probiotic E. coli Nissle 1917 (EcN) to a genetically-engineered murine model of CRC predisposition and orthotopic models of CRC. We next undertake an interventional, double-blind, dual-centre, prospective clinical trial, in which CRC patients take either placebo or EcN for two weeks prior to resection of neoplastic and adjacent normal colorectal tissue (ACTRN12619000210178). We detect enrichment of EcN in tumor samples over normal tissue from probiotic-treated patients (primary outcome of the trial). Next, we develop early CRC intervention strategies. To detect lesions, we engineer EcN to produce a small molecule, salicylate. Oral delivery of this strain results in increased levels of salicylate in the urine of adenoma-bearing mice, in comparison to healthy controls. To assess therapeutic potential, we engineer EcN to locally release a cytokine, GM-CSF, and blocking nanobodies against PD-L1 and CTLA-4 at the neoplastic site, and demonstrate that oral delivery of this strain reduces adenoma burden by ~50%. Together, these results support the use of EcN as an orally-deliverable platform to detect disease and treat CRC through the production of screening and therapeutic molecules.

Colorectal cancer detection and treatment with engineered probiotics.

Bioengineered probiotics enable new opportunities to improve colorectal cancer (CRC) screening, prevention and treatment strategies. Here, we demonstrate the phenomenon of selective, long-term colonization of colorectal adenomas after oral delivery of probiotic E. coli Nissle 1917 (EcN) to a genetically-engineered murine model of CRC predisposition. We show that, after oral administration, adenomas can be monitored over time by recovering EcN from stool. We also demonstrate specific colonization of EcN to solitary neoplastic lesions in an orthotopic murine model of CRC. We then exploit this neoplasia-homing property of EcN to develop early CRC intervention strategies. To detect lesions, we engineer EcN to produce a small molecule, salicylate, and demonstrate that oral delivery of this strain results in significantly increased levels of salicylate in the urine of adenoma-bearing mice, in comparison to healthy controls. We also assess EcN engineered to locally release immunotherapeutics at the neoplastic site. Oral delivery to mice bearing adenomas, reduced adenoma burden by ∻50%, with notable differences in the spatial distribution of T cell populations within diseased and healthy intestinal tissue, suggesting local induction of robust anti-tumor immunity. Together, these results support the use of EcN as an orally-delivered platform to detect disease and treat CRC through its production of screening and therapeutic molecules.

Cancer Therapeutics-related Cardiac Dysfunction in Patients Treated With Immune Checkpoint Inhibitors: An Understudied Manifestation.

The widespread use of immune checkpoint inhibitors (ICI) has become a mainstay of care for a variety of malignancies. However, these therapies portend a range of adverse effects, including a potentially fatal form of cardiotoxicity which to date has not been elucidated. We aimed to evaluate the baseline characteristics of ICI-mediated cardiotoxicity. We performed a retrospective study evaluating patients treated with ICI who performed at least 2 echocardiography examinations, before and after the initiation of ICI. Cardiotoxicity was defined as Cancer Therapeutics-related Cardiac Dysfunction (CTRCD) development, with an absolute left ventricular ejection fraction reduction of >10%, to a value <53%. Fifty-two patients were included with a male preponderance (65%) and a mean age of 66 (±12) years. Twelve (23%) patients developed CTRCD, of which 2 patients were diagnosed with myocarditis. Among the CTRCD group, patients tended to be older and more likely to have baseline diastolic dysfunction: lower e' septal (P=0.026), higher E/e' septal (P=0.035), and a trend of E/e' average (P=0.076). All-cause and cardiovascular hospitalizations were significantly more common among the CTRCD group (P=0.028 and 0.001, respectively). Higher prevalence of cardiovascular mortality was observed among the CTRCD group (25% vs. 2%, P=0.034). We evaluated the development of CTRCD among patients treated with ICI therapies. Our findings suggest that baseline diastolic parameters may be associated with CTRCD development assisting in the early diagnosis of ICI-induced cardiac injury.

Diastolic function as an early marker for systolic dysfunction and all-cause mortality among cancer patients.

BACKGROUND: Increased survival among active cancer patients exposes a wide range of side effects, including cardiotoxicity, manifested by systolic dysfunction and associated with morbidity and mortality. Early diagnosis of subclinical function changes and cardiac damage is essential in the management of these patients. Diastolic dysfunction is considered common among cancer patients; however, its effect on systolic dysfunction or mortality is still unknown. METHODS: Data were collected as part of the Israel Cardio-Oncology Registry, enrolling and prospectively following all patients evaluated in the cardio-oncology clinic in the Tel Aviv Sourasky Medical Center. All patients underwent echocardiographic examinations including evaluation of diastolic parameters and global longitudinal strain (GLS). Systolic dysfunction was defined as either an absolute reduction >10% in left ventricular ejection fraction to a value below 53% or GLS relative reduction >10% between the 1st and 3rd echocardiography examinations. RESULTS: Overall, 190 active cancer patients were included, with a mean age of 58 ± 15 years and a female predominance (78%). During a median follow-up of 243 days (interquartile ranges [IQR]: 164-401 days), 62 (33%) patients developed systolic dysfunction. Over a median follow-up of 789 days (IQR: 521-968 days), 29 (15%) patients died. There were no significant differences in baseline cardiac risk factors between the groups. Using multivariate analysis, E/e' lateral and e' lateral emerged as significantly associated with systolic dysfunction development and all-cause mortality (P = .015). CONCLUSION: Among active cancer patients, evaluation of diastolic function may provide an early marker for the development of systolic dysfunction, as well as all-cause mortality.

Re-introducing immunotherapy in patients surviving immune checkpoint inhibitors-mediated myocarditis.

BACKGROUND: Immune checkpoint inhibitors (ICI) have transformed the standard care of cancer treatment. Recent case reports describe ICI-mediated myocarditis with an atypical presentation and fatal potential which lead to permanent interruption of immunotherapy. OBJECTIVES: To characterize ICI-mediated myocarditis and re-introduction to immunotherapy. METHODS: During 2019, 849 patients were treated with ICI at Tel Aviv Sourasky Medical Center for the diagnosis of lung adenocarcinoma, gastric adenocarcinoma, urothelial carcinoma, and hepatocellular carcinoma. Overall, seven (0.8%) patients were diagnosed with ICI-mediated myocarditis, according to the European Society of Cardiology guidelines of myocarditis 2013. We retrospectively evaluated their presentation, severity, and clinical outcomes. RESULTS: Among the seven patients, only one had a history of cardiac disease. The majority were diagnosed with lung adenocarcinoma and treated with anti-programmed death-1 antibody. All patients were treated with single-agent ICI. Most patients presented with cardiac symptoms, elevated troponin and typical cardiac magnetic resonance; however, only three had reduced ejection fraction. Overall, three patients were chosen for re-introduction with concomitant low dose steroids and weekly troponin follow-up. Two patients diagnosed with grade I and II renewed therapy successfully with no recurrence of symptoms and improvement in disease burden. The one patient diagnosed with grade III developed worsening of cardiac symptoms after the 1st cycle and, therefore, therapy was interrupted permanently. CONCLUSIONS: ICI-mediated myocarditis is potentially fatal and leads to permanent interruption of life-saving cancer therapy. The current data suggest that re-introduction may be considered in low-grade patients; however, a better definition of the diagnosis and grading is needed.

Diagnostic workup of early-stage breast cancer: can we choose more wisely?

INTRODUCTION: Current international guidelines, including the Choosing Wisely Initiative, recommends against the routine use of systemic imaging studies or tumor markers in early-stage breast cancer. Accumulating data suggests that adherence to these guidelines is low. We aimed to investigate the execution of unnecessary diagnostic tests among Israeli breast cancer patients and identify factors associated with their performance. METHODS: A retrospective analysis was conducted involving a database of early breast cancer patients treated at Tel Aviv Sourasky Medical Center. A survey was distributed among Israeli surgeons and oncologists specializing in breast cancer treatment. RESULTS: The study included early breast cancer patients (n = 178), who have no indication for completing systemic evaluation. Nearly half of the patients (76, 42%) were referred to 128 unjustified diagnostic studies, with the most common referral comprising a PET-CT (n = 39 30.5%). As expected, none of the tests led to any change in either disease staging or alteration in clinical management. Variables associated with systemic evaluation included younger age (61.8% for < 50 years vs 38.9% for > 50 years, p = 0.02), diagnosis by palpable mass compared to screening mammography (26.9% vs 52.9% p = 0.043, respectively) and higher tumor grade (33.7% vs 52.2% p = 0.02, respectively). In concordance with the findings of the database, the physicians' survey revealed low adherence to guidelines and a role of the treating physicians' subjective feelings. Doctors were more likely to recommend unnecessary studies when presented with a clinical case as an image, than to an informative question. CONCLUSIONS: Our data indicate a high rate of non-adherence to guidelines, physicians recommending extensive systemic evaluation for women with early breast cancer. These deviations from the guidelines are associated with subjective factors, some of them being physician-dependent. Initiatives aimed at improving adherence to guidelines, and specifically to guidelines recommending "doing less" should therefore include not just knowledge-based education but also encourage conversation about what is appropriate and necessary.

CD11b+Ly6G+ myeloid-derived suppressor cells promote liver regeneration in a murine model of major hepatectomy.

Liver regeneration depends on sequential activation of pathways and cells involving the remaining organ in recovery of mass. Proliferation of parenchyma is dependent on angiogenesis. Understanding liver regeneration-associated neovascularization may be useful for development of clinical interventions. Myeloid-derived suppressor cells (MDSCs) promote tumor angiogenesis and play a role in developmental processes that necessitate rapid vascularization. We therefore hypothesized that the MDSCs could play a role in liver regeneration. Following partial hepatectomy, MDSCs were enriched within regenerating livers, and their depletion led to increased liver injury and postoperative mortality, reduced liver weights, decreased hepatic vascularization, reduced hepatocyte hypertrophy and proliferation, and aberrant liver function. Gene expression profiling of regenerating liver-derived MDSCs demonstrated a large-scale transcriptional response involving key pathways related to angiogenesis. Functionally, enhanced reactive oxygen species production and angiogenic capacities of regenerating liver-derived MDSCs were confirmed. A comparative analysis revealed that the transcriptional response of MDSCs during liver regeneration resembled that of peripheral blood MDSCs during progression of abdominal tumors, suggesting a common MDSC gene expression profile promoting angiogenesis. In summary, our study shows that MDSCs contribute to early stages of liver regeneration possibly by exerting proangiogenic functions using a unique transcriptional program.-Nachmany, I., Bogoch, Y., Sivan, A., Amar, O., Bondar, E., Zohar, N., Yakubovsky, O., Fainaru, O., Klausner, J. M., Pencovich, N. CD11b+Ly6G+ myeloid-derived suppressor cells promote liver regeneration in a murine model of major hepatectomy.

Cancer Immunotherapy Targets Based on Understanding the T Cell-Inflamed Versus Non-T Cell-Inflamed Tumor Microenvironment.

Most cancers express tumor antigens that can be recognized by T cells of the host. The fact that cancers become clinically evident nonetheless implies that immune escape must occur. Two major subsets of human melanoma metastases have been identified based on gene expression profiling. One subgroup has a T cell-inflamed phenotype that includes expression of chemokines, T cell markers, and a type I IFN signature. In contrast, the other major subset lacks this phenotype and has been designated as non-T cell-inflamed. The mechanisms of immune escape are likely distinct in these two phenotypes, and therefore the optimal immunotherapeutic interventions necessary to promote clinical responses may be different. The T cell-inflamed tumor microenvironment subset shows the highest expression of negative regulatory factors, including PD-L1, IDO, FoxP3+ Tregs, and evidence for T cell-intrinsic anergy. Therapeutic strategies to overcome these inhibitory mechanisms are being pursued, and anti-PD-1 mAbs have been FDA approved. The presence of multiple inhibitory mechanisms in the same tumor microenvironment argues that combination therapies may be advantageous, several of which are in clinical testing. A new paradigm may be needed to promote de novo inflammation in cases of the non-T cell-infiltrated tumor microenvironment. Natural innate immune sensing of tumors appears to occur via the host STING pathway, type I IFN production, and cross-priming of T cells via CD8α+ DCs. New strategies are being developed to engage this pathway therapeutically, such as through STING agonists. The molecular mechanisms that mediate the presence or absence of the T cell-inflamed tumor microenvironment are being elucidated using parallel genomics platforms. The first oncogene pathway identified that mediates immune exclusion is the Wnt/ß-catenin pathway, suggesting that new pharmacologic strategies to target this pathway should be developed to restore immune access to the tumor microenvironment.

Dormant breast cancer micrometastases reside in specific bone marrow niches that regulate their transit to and from bone.

Breast cancer metastatic relapse can occur years after therapy, indicating that disseminated breast cancer cells (BCCs) have a prolonged dormant phase before becoming proliferative. A major site of disease dissemination and relapse is bone, although the critical signals that allow circulating BCCs to identify bone microvasculature, enter tissue, and tether to the microenvironment are poorly understood. Using real-time in vivo microscopy of bone marrow (BM) in a breast cancer xenograft model, we show that dormant and proliferating BCCs occupy distinct areas, with dormant BCCs predominantly found in E-selectin- and stromal cell-derived factor 1 (SDF-1)-rich perisinusoidal vascular regions. We use highly specific inhibitors of E-selectin and C-X-C chemokine receptor type 4 (CXCR4) (SDF-1 receptor) to demonstrate that E-selectin and SDF-1 orchestrate opposing roles in BCC trafficking. Whereas E-selectin interactions are critical for allowing BCC entry into the BM, the SDF-1/CXCR4 interaction anchors BCCs to the microenvironment, and its inhibition induces mobilization of dormant micrometastases into circulation. Homing studies with primary BCCs also demonstrate that E-selectin regulates their entry into bone through the sinusoidal niche, and immunohistochemical staining of patient BMs shows dormant micrometastatic disease adjacent to SDF-1(+) vasculature. These findings shed light on how BCCs traffic within the host, and suggest that simultaneous blockade of CXCR4 and E-selectin in patients could molecularly excise dormant micrometastases from the protective BM environment, preventing their emergence as relapsed disease.

Tumor and Host Factors Controlling Antitumor Immunity and Efficacy of Cancer Immunotherapy.

Despite recent clinical advances in immunotherapy, a fraction of cancer patients fails to respond to these interventions. Evidence from preclinical mouse models as well as clinical samples has provided evidence that the extent of activated T cell infiltration within the tumor microenvironment is associated with clinical response to immunotherapies including checkpoint blockade. Therefore, understanding the molecular mechanisms mediating the lack of T cell infiltration into the tumor microenvironment will be instrumental for the development of new therapeutic strategies to render those patients immunotherapy responsive. Recent data have suggested that major sources of intersubject heterogeneity include differences in somatic mutations in specific oncogene pathways between cancers of individual subjects and also environmental factors including commensal microbial composition. Successful identification of such causal factors should lead to new therapeutic approaches that may facilitate T cell entry into noninflamed tumors and expand the fraction of patients capable of responding to novel immunotherapies.

Commensal Bifidobacterium promotes antitumor immunity and facilitates anti-PD-L1 efficacy.

T cell infiltration of solid tumors is associated with favorable patient outcomes, yet the mechanisms underlying variable immune responses between individuals are not well understood. One possible modulator could be the intestinal microbiota. We compared melanoma growth in mice harboring distinct commensal microbiota and observed differences in spontaneous antitumor immunity, which were eliminated upon cohousing or after fecal transfer. Sequencing of the 16S ribosomal RNA identified Bifidobacterium as associated with the antitumor effects. Oral administration of Bifidobacterium alone improved tumor control to the same degree as programmed cell death protein 1 ligand 1 (PD-L1)-specific antibody therapy (checkpoint blockade), and combination treatment nearly abolished tumor outgrowth. Augmented dendritic cell function leading to enhanced CD8(+) T cell priming and accumulation in the tumor microenvironment mediated the effect. Our data suggest that manipulating the microbiota may modulate cancer immunotherapy.