A47 THE GUT MICROBIOTA INFLUENCES COLONIC HEALING AFTER SURGERY IN PATIENTS UNDERGOING BOWEL RESECTION FOR COLORECTAL CANCER

Background

The standard treatment of colorectal cancer (CRC) consists of a surgical resection of the colonic segment with the tumor, followed by a reconnection of the remaining bowel ends, or "anastomosis". The anastomosis may fail to heal in up to 20% of patients, which leads to anastomotic leak, a major complication that increases postoperative morbidity and mortality. This complication is unpredictable and its causes remain poorly understood.

Purpose

The objective of this study is to investigate the possible role of the gut microbiome in anastomotic healing after surgery in patients with CRC.

Method

We collected preoperative fecal samples and intraoperative mucosal samples from CRC patients undergoing surgery with anastomosis. The gut microbiota of patients with AL and of others that presented optimal healing after surgery was analyzed and compared using the Anchor 16S pipeline. To assess the role of the patients' microbiota in healing, fecal microbiota transplantation (FMT) was performed in mice using preoperative fecal samples from CRC patients with and without AL. Mice were then subjected to colonic surgery using a colonic anastomosis model. Six days after surgery, anastomotic healing was assessed macroscopically and microscopically. The gut barrier function was also assessed. The gut microbiota composition was compared between the groups colonized with samples from patients with and without AL to detect potential differences.

Result(s)

Mice colonized by FMT with the microbiota of donors with AL displayed poor anastomotic healing macroscopically, and a weaker wound microscopically. These same mice displayed a weaker gut barrier, as objectified by higher bacterial translocation to the spleen. The anastomoses of mice receiving the microbiota of AL donors displayed lower concentrations of collagen and fibronectin and higher inflammatory cytokines and collagenolytic enzymes, indicating poor extracellular matrix formation and collagen degradation locally.The beta-diversity of the gut microbiota was significantly different between mice receiving the microbiota of donors with and without AL, and several bacterial species were differentially abundant between the two groups.

Conclusion(s)

The preoperative gut microbiota in CRC patients who experience anastomotic leak after surgery induces poor anastomotic healing in mice and a weaker gut barrier after colonic surgery. Several bacterial species were found to be associated with the healing process.

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CIHR, Other

Please indicate your source of funding;

NSERC, FRQS, New Frontiers in Research, Montreal Cancer Institute.

Disclosure of Interest

None Declared

A269 THE MODULATION OF INTESTINAL INFLAMMATION BY PARABACTEROIDES GOLDSTEINII IN MURINE MODELS OF COLITIS

Background

Inflammatory bowel diseases (IBDs), comprised mainly of Crohn’s disease and ulcerative colitis, are characterized by chronic and relapsing intestinal inflammation. Though the etiology of IBDs is not entirely understood, it is thought that an imbalance of the gut microbiota is one contributing factor, making it a potential target for the treatment of IBDs.

Purpose

This study aims to examine how the potential probiotic Parabacteroides goldsteinii modulates intestinal inflammation in the context of experimental colitis.

Method

Wild type C57BL/6 mice were divided into three groups. One group was given phosphate-buffered saline (PBS) via oral gavage without any further treatment. The second group was treated with 1% dextran sodium sulfate (DSS) for twelve days induce colitis and given PBS every three days. Finally, the third group was also treated with 1% DSS for twelve days and given P. goldsteinii via oral gavage every three days. Weight loss, stool consistency, and intestinal bleeding were monitored and were used to calculate the Disease Activity Index (DAI) daily. Postmortem, colon length was measured, and inflammation score was evaluated on hematoxylin and eosin-stained samples of the colon and spleen. Finally, interleukin (IL)-6 levels were measured in the colon tissue and the serum by ELISA.

Result(s)

Colonization was confirmed at day three after gavage by real-time PCR. Preliminary results show that DSS-treated mice lost significantly more weight by day twelve than mice colonized with P. goldsteinii. Additionally, on days eight and twelve, mice colonized with P. goldsteinii had significantly lower DAI scores than mice that received only PBS. Finally, mice colonized with P. goldsteinii had significantly longer colons than those that received only PBS.

Conclusion(s)

The preliminary data indicates that mice colonized with P. goldsteinii had less severe symptoms of colitis than mice only given PBS. This suggests that P. goldsteinii may attenuate inflammation in mice treated with DSS.

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CIHR, Other

Please indicate your source of funding;

ICM

Disclosure of Interest

None Declared

A271 THE MODULATION OF INTESTINAL INFLAMMATION BY PARABACTEROIDES GOLDSTEINII IN EXPERIMENTAL MURINE COLITIS

Background

Inflammatory bowel diseases (IBDs), comprised mainly of Crohn’s disease and ulcerative colitis, are characterized by chronic and relapsing intestinal inflammation. Though the etiology of IBDs is not entirely understood, it is thought that an imbalance of the gut microbiota is one contributing factor, making it a potential target for the treatment of IBDs.

Purpose

This study aims to examine how the potential probiotic Parabacteroides goldsteinii modulates intestinal inflammation in the context of experimental colitis.

Method

Wild type C57BL/6 mice were divided into three groups. One group was given phosphate-buffered saline (PBS) via oral gavage without any further treatment. The second group was treated with 1% dextran sodium sulfate (DSS) for twelve days induce colitis and given PBS every three days. Finally, the third group was also treated with 1% DSS for twelve days and given P. goldsteinii via oral gavage every three days. Weight loss, stool consistency, and intestinal bleeding were monitored and were used to calculate the Disease Activity Index (DAI) daily. Postmortem, colon length was measured, and inflammation score was evaluated on hematoxylin and eosin-stained samples of the colon and spleen. Finally, inflammatory cytokine levels were measured in the colon tissue and the serum by multiplex assay.

Result(s)

Colonization was confirmed at day three after gavage by real-time PCR. Preliminary results show that DSS-treated mice lost significantly more weight by day twelve than mice colonized with P. goldsteinii. Additionally, on days eight and twelve, mice colonized with P. goldsteinii had significantly lower DAI scores than mice that received only PBS. Finally, mice colonized with P. goldsteinii had significantly longer colons than those that received only PBS.

Conclusion(s)

The preliminary data indicates that mice colonized with P. goldsteinii had less severe symptoms of colitis than mice only given PBS. This suggests that P. goldsteinii may attenuate inflammation in mice treated with DSS.

Please acknowledge all funding agencies by checking the applicable boxes below

CIHR

Disclosure of Interest

None Declared

Erratum: Therapeutic landscape of metastatic non-small-cell lung cancer in Canada in 2020

[This corrects the article DOI: 10.3747/co.27.5953.].

Therapeutic landscape of metastatic non-small-cell lung cancer in Canada in 2020

Lung cancer is the most commonly diagnosed cancer in Canada and remains associated with high mortality. Nevertheless, recent advances in the fields of immuno-oncology and precision medicine have led to significant improvements in clinical outcome in metastatic non-small-cell lung cancer (nsclc). Those improvements were facilitated by a greater understanding of the biologic classification of nsclc, which catalyzed discoveries of novel therapies. Here, we present a comprehensive review of the recent avalanche of practice-changing trials in metastatic nsclc, and we offer an approach to the management of this disease from a Canadian perspective. We begin with an overview of the pathologic and molecular characterization of metastatic nsclc. Next, we review the indications for currently approved immune checkpoint inhibitors, and we provide an approach to the management of disease with a driver mutation. Finally, we address future avenues in both diagnostics and therapeutics for patients with advanced and metastatic nsclc.

The negative impact of antibiotics on outcomes in cancer patients treated with immunotherapy: a new independent prognostic factor?

Immune-checkpoint inhibitors (ICI) now represent the standard of care for several cancer types. In pre-clinical models, absence of an intact gut microbiome negatively impacted ICI efficacy and these findings permitted to unravel the importance of the commensal microbiota in immuno-oncology. Recently, multiple clinical studies including more than 1800 patients in aggregate demonstrated the negative predictive impact of treatments with broad-spectrum antibiotics (ATB) on cancer patients receiving ICI. Altogether, these results have led to the hypothesis that ATB-induced dysbiosis might influence the clinical response through the modulation of the gut microbiome. Controversy still remains, as ATB treatment might simply constitute a surrogate marker of unfit or immunodeficient patients. In this review, we summarize recent publications addressing the impact of the gut microbiome on ICI efficacy, discuss currently available data on the effect of ATB administered in different time-frames respect to ICI initiation, and finally, evoke the therapeutic implications of these findings.

T-cell bispecific antibodies in node-positive breast cancer: novel therapeutic avenue for MHC class I loss variants

BACKGROUND

Tumor-infiltrating lymphocytes (TILs) represent a prognostic factor for survival in primary breast cancer (BC). Nonetheless, neoepitope load and TILs cytolytic activity are modest in BC, compromising the efficacy of immune-activating antibodies, which do not yet compete against immunogenic chemotherapy.

PATIENTS AND METHODS

We analyzed by functional flow cytometry the immune dynamics of primary and metastatic axillary nodes [metastatic lymph nodes (mLN)] in early BC (EBC) after exposure to T-cell bispecific antibodies (TCB) bridging CD3ε and human epidermal growth factor receptor 2 (HER2) or Carcinoembryonic Antigen-Related Cell Adhesion Molecule 5 (CEACAM5), before and after chemotherapy. Human leukocyte antigen (HLA) class I loss was assessed by whole exome sequencing and immunohistochemistry. One hundred primary BC, 64 surrounding 'healthy tissue' and 24 mLN-related parameters were analyzed.

RESULTS

HLA loss of heterozygosity was observed in EBC, at a clonal and subclonal level and was associated with regulatory T cells and T-cell immunoglobulin and mucin-domain-3 expression restraining the immuno-stimulatory effects of neoadjuvant chemotherapy. TCB bridging CD3ε and HER2 or CEACAM5 could bypass major histocompatibility complex (MHC) class I loss, partially rescuing T-cell functions in mLN.

CONCLUSION

TCB should be developed in BC to circumvent low MHC/peptide complexes.

Multiple remissions of extracavitary primary effusion lymphoma treated with a single cycle of liposomal doxorubicin in a patient infected with HIV

Primary effusion lymphoma (pel) is a rare human herpesvirus 8 (hhv8)-related large B cell lymphoma with plasmablastic, immunoblastic, or anaplastic features that often carries a poor prognosis. This lymphoma occurs mainly in patients with hiv infection, most often with Epstein-Barr virus (ebv) co-infection, and usually presents as body cavity effusions or, less commonly, as extracavitary lesions without effusion (ec-pel). Chemotherapeutic treatment options are limited and require concurrent antiretroviral therapy (art). Here, we report the case of an adult patient with hiv infection and chronic hepatitis E virus (hev) co-infection who had low CD4 T cell recovery after years of art. The patient then developed a cutaneous ec-pel which rapidly regressed after 1 cycle of liposomal doxorubicin (ld) for his Kaposi sarcoma (ks) before treatment with chop chemotherapy. He had previously received numerous cycles of ld for cutaneous ks over 2 years. Because of the patient's low CD4 T cell count, hev co-infection, and earlier unexpected remission of ec-pel before chop, the patient opted for a single trial of ld before other options. Surprisingly, he experienced a complete remission lasting 18 months. Subsequently, his ec-pel relapsed twice at 31 and at 41 months after the initial diagnosis. Upon recurrence, a similar single cycle of ld was given, which again induced remission. The patient today is in complete remission after a total of 4 ld infusions over 54 months. This patient represents a unique case of hiv-with-hhv8-related, ebv-negative ec-pel with chronic hev coinfection, in which rapid remission was achieved after a single cycle of ld, suggesting an antiviral response in addition to the chemotherapeutic effect.

Negative association of antibiotics on clinical activity of immune checkpoint inhibitors in patients with advanced renal cell and non-small-cell lung cancer

Background

The composition of gut microbiota affects antitumor immune responses, preclinical and clinical outcome following immune checkpoint inhibitors (ICI) in cancer. Antibiotics (ATB) alter gut microbiota diversity and composition leading to dysbiosis, which may affect effectiveness of ICI.

Patients and methods

We examined patients with advanced renal cell carcinoma (RCC) and non-small-cell lung cancer (NSCLC) treated with anti-programmed cell death ligand-1 mAb monotherapy or combination at two academic institutions. Those receiving ATB within 30 days of beginning ICI were compared with those who did not. Objective response, progression-free survival (PFS) determined by RECIST1.1 and overall survival (OS) were assessed.

Results

Sixteen of 121 (13%) RCC patients and 48 of 239 (20%) NSCLC patients received ATB. The most common ATB were β-lactam or quinolones for pneumonia or urinary tract infections. In RCC patients, ATB compared with no ATB was associated with increased risk of primary progressive disease (PD) (75% versus 22%, P < 0.01), shorter PFS [median 1.9 versus 7.4 months, hazard ratio (HR) 3.1, 95% confidence interval (CI) 1.4-6.9, P < 0.01], and shorter OS (median 17.3 versus 30.6 months, HR 3.5, 95% CI 1.1-10.8, P = 0.03). In NSCLC patients, ATB was associated with similar rates of primary PD (52% versus 43%, P = 0.26) but decreased PFS (median 1.9 versus 3.8 months, HR 1.5, 95% CI 1.0-2.2, P = 0.03) and OS (median 7.9 versus 24.6 months, HR 4.4, 95% CI 2.6-7.7, P < 0.01). In multivariate analyses, the impact of ATB remained significant for PFS in RCC and for OS in NSCLC.

Conclusion

ATB were associated with reduced clinical benefit from ICI in RCC and NSCLC. Modulatation of ATB-related dysbiosis and gut microbiota composition may be a strategy to improve clinical outcomes with ICI.

Immuno-oncology-101: overview of major concepts and translational perspectives

Cancer immunotherapy is demonstrating impressive clinical benefit in different malignancies and clinical oncologists are increasingly turning their attention to immune-oncology. It is now well recognized that innate and adaptive immune cells infiltrating tumors are associated with clinical outcomes and responses to treatments, and can be harnessed to patients' benefit. Considerable advances have also been made in understanding how cancers escape from immune attack. Targeting of immunological escape processes regulated by the expression of immune checkpoint receptors and ligands and the down-modulation of tumor antigen presentation is the basis of immuno-oncology treatments. Despite recent achievements, there remain a number of unresolved issues in order to successfully implement cancer immunotherapy in many cancers. Importantly, clinical biomarkers are still needed for better optimization of emerging combination immunotherapies and better treatment tailoring. In this review, we summarize the function of innate and adaptive immune cells in anti-tumor immunity and the general mechanisms exploited by tumor cells to escape and inhibit immune responses as well as therapeutic strategies developed to overcome these mechanisms and discuss emerging biomarkers in immuno-oncology.

Imatinib for highly chemoresistant Kaposi sarcoma in a patient with long-term HIV control: a case report and literature review

Kaposi sarcoma (ks) is a vascular tumour caused by oncogenic human herpesvirus type 8; it often occurs with hiv-associated immunosuppression. Numerous cellular signalling pathways are involved in the pathogenesis of ks, among which receptor tyrosine kinases such as the c-Kit and platelet-derived growth factor receptors play an important role. Imatinib mesylate, a tyrosine kinase inhibitor, has resulted in partial regression of ks lesions in one third of treated patients, but its mechanism of action remains unclear. Here, we report the case of a white man with recurrent ks despite well-suppressed hiv infection and multiple chemotherapies who received imatinib and showed a complete and sustained tumour response. To our knowledge, this report is the first showing the value of imatinib in the management of ks in the context of long-lasting hiv control with adequate quantitative CD4 recovery. Our case indicates that imatinib can be a treatment option for highly chemoresistant recurrent ks in patients on long-term antiretroviral therapy.