Checkpoint inhibitor responses can be regulated by the gut microbiota - A systematic review.

BACKGROUND: Evidence suggests that the human gut microbiota modulates the treatment response of immune checkpoint inhibitors (ICI) in cancer. Thus, finding predictive biomarkers in the fecal gut microbiota of patients who are less likely to respond to ICI would be valuable. This systematic review aimed to investigate the association between fecal gut microbiota composition and ICI-treatment response in patients with cancer. METHODS: EMBASE, Medline, and Cochrane Library databases were searched using the "Participants, Interventions, Comparisons, and Outcomes" (PICO) process to locate studies including participants with solid cancers treated with ICI intervention. The comparator was the gut microbiota, and the outcomes were oncological outcomes such as response rates and progression-free survival. Study data were synthesized qualitatively in a systematic narrative synthesis, and the risk of bias in the studies was assessed. RESULTS: Two reviewers screened 2092 abstracts independently, and 140 studies were read as full-text reports and assessed for eligibility. Eighteen studies were included with 775 patients with different types of solid cancers who received anti-PD-1, anti-PD-L1, or anti-CTLA-4 therapy. Distinct patterns were observed in the patients' fecal samples. Some bacterial species were reported to be present in responders and non-responders, while others were present only in one group. The most reported species associated with better prognosis were Faecalibacterium prausnitzii, Streptococcus parasanguinis, Bacteroides caccae, and Prevotella copri. In contrast, the most reported species associated with poor prognosis were Blautia obeum and Bacteroides ovatus. CONCLUSION: Distinct microbiota features were associated with good and poor prognoses in ICI-treated patients with cancer.

Neoadjuvant intratumoral influenza vaccine treatment in patients with proficient mismatch repair colorectal cancer leads to increased tumor infiltration of CD8+ T cells and upregulation of PD-L1: a phase 1/2 clinical trial.

BACKGROUND: In colorectal cancer, the effects of immune checkpoint inhibitors are mostly limited to patients with deficient mismatch repair tumors, characterized by a high grade infiltration of CD8+T cells. Interventions aimed at increasing intratumoral CD8+T-cell infiltration in proficient mismatch repair tumors are lacking. METHODS: We conducted a proof of concept phase 1/2 clinical trial, where patients with non-metastasizing sigmoid or rectal cancer, scheduled for curative intended surgery, were treated with an endoscopic intratumorally administered neoadjuvant influenza vaccine. Blood and tumor samples were collected before the injection and at the time of surgery. The primary outcome was safety of the intervention. Evaluation of pathological tumor regression grade, immunohistochemistry, flow cytometry of blood, tissue bulk transcriptional analyses, and spatial protein profiling of tumor regions were all secondary outcomes. RESULTS: A total of 10 patients were included in the trial. Median patient age was 70 years (range 54-78), with 30% women. All patients had proficient mismatch repair Union of International Cancer Control stage I-III tumors. No endoscopic safety events occurred, with all patients undergoing curative surgery as scheduled (median 9 days after intervention). Increased CD8+T-cell tumor infiltration was evident after vaccination (median 73 vs 315 cells/mm2, p<0.05), along with significant downregulation of messenger RNA gene expression related to neutrophils and upregulation of transcripts encoding cytotoxic functions. Spatial protein analysis showed significant local upregulation of programmed death-ligand 1 (PD-L1) (adjusted p value<0.05) and downregulation of FOXP3 (adjusted p value<0.05). CONCLUSIONS: Neoadjuvant intratumoral influenza vaccine treatment in this cohort was demonstrated to be safe and feasible, and to induce CD8+T-cell infiltration and upregulation of PD-L1 proficient mismatch repair sigmoid and rectal tumors. Definitive conclusions regarding safety and efficacy can only be made in larger cohorts. TRIAL REGISTRATION NUMBER: NCT04591379.

Deeper sections reveal residual tumor cells in rectal cancer specimens diagnosed with pathological complete response following neoadjuvant treatment.

Guidelines and requirements for diagnosing pathological complete response (pCR) in rectal adenocarcinoma following neoadjuvant treatment vary, and there is currently no consensus on the appropriate number of sections to examine per formalin-fixed, paraffin-embedded (FFPE) tissue block. The consequences of systematic use of deeper sections on the diagnostic accuracy and prognosis for patients classified as ypT0 rectal cancer were investigated. In this retrospective study, 23 out of 155 patients who underwent neoadjuvant therapy and surgical resection between 2015 and 2020 were diagnosed with ypT0 rectal cancer. Three additional deeper sections were cut from each FFPE block from the primary tumor site and reviewed for presence of residual tumor cells. Additional sections revealed residual viable tumor cells in seven patients (30.4%), reducing the rate of pCR in the cohort from 14.8 to 10.3%. Of the seven patients, three patients later had local recurrence or distant metastasis during the follow-up period, compared with one patient with no residual tumor cells in deeper sections (p = 0.07). A nonsignificant reduction in disease-free survival (p = 0.08) was observed in the patients with residual tumor. Systematic use of deeper sections in evaluation of tumor regression in rectal cancer reveals the presence of residual tumor cells in a subset of patients originally diagnosed with pCR based on a single section per FFPE block. Although the results are not statistically significant, it cannot be excluded that accurately distinguishing complete from near-complete response may be clinically relevant for prognostic prediction.

An exploration of immunohistochemistry-based prognostic markers in patients undergoing curative resections for colon cancer.

BACKGROUND: The immune system recognizes and destroys cancer cells. However, cancer cells develop mechanisms to avoid detection by expressing cell surface proteins. Specific tumour cell surface proteins (e.g. HLA-G, PD-L1, CDX2) either alone or in combination with the relative presence of immune cells (CD3 and CD8 positive T-cells) in the tumour tissue may describe the cancer cells' ability to escape eradication by the immune system. The aim was to investigate the prognostic value of immunohistochemical markers in patients with colon cancer. METHODS: We conducted a retrospective study including patients diagnosed with pT3 and pT4 colon cancers. Immunohistochemical staining with HLA-G, PD-L1, CDX2, CD3, and CD8 was performed on tissue samples with representation of the invasive margin. PD-L1 expression in tumour cells and immune cells was reported conjointly. The expression of CD3 and CD8 was reported as a merged score based on the expression of both markers in the invasive margin and the tumour centre. Subsequently, a combined marker score was established based on all of the markers. Each marker added one point to the score when unfavourable immunohistochemical features was present, and the score was categorized as low, intermediate or high depending on the number of unfavourable stains. Hazard ratios for recurrence, disease-free survival and mortality were calculated. RESULTS: We included 188 patients undergoing colon cancer resections in 2011-2012. The median follow-up was 41.7 months, during which 41 (21.8%) patients had recurrence and 74 (39.4%) died. In multivariable regression analysis positive HLA-G expression (HR = 3.37, 95%CI [1.64-6.93]) was associated with higher recurrence rates, while a preserved CDX2 expression (HR = 0.23, 95%CI [0.06-0.85]) was associated with a lower risk of recurrence. An intermediate or high combined marker score was associated with increased recurrence rates (HR = 20.53, 95%CI [2.68-157.32] and HR = 7.56, 95%CI [1.06-54.16], respectively). Neither high expression of PD-L1 nor high CD3-CD8 score was significantly associated with recurrence rates. Patients with a high CD3-CD8 score had a significantly longer DFS and OS. CONCLUSIONS: In tumour cells, expression of HLA-G and loss of CDX2 expression were associated with cancer recurrence. In addition, a combination of certain tumour tissue biomarkers was associated with colorectal cancer recurrence.

[Increasing incidence of colorectal cancer in young patients].

For the past decades, an increase in the incidence of colorectal cancer in young patients has been reported in several countries, including Denmark, and efforts need to be taken in order to halt this tendency. This review characterises the clinical and pathological attributes of young patients with early-onset colorectal cancer (EOCRC). Risk factors such as smoking and sedentary lifestyle have been found to be associated with EOCRC. Further studies are needed to evaluate, if the age of patients entering the Danish screening programme for bowel cancer should be lowered.

In vivo and ex vivo sentinel node mapping does not identify the same lymph nodes in colon cancer.

INTRODUCTION: Identification of lymph nodes and pathological analysis is crucial for the correct staging of colon cancer. Lymph nodes that drain directly from the tumor area are called "sentinel nodes" and are believed to be the first place for metastasis. The purpose of this study was to perform sentinel node mapping in vivo with indocyanine green and ex vivo with methylene blue in order to evaluate if the sentinel lymph nodes can be identified by both techniques. METHODS: Patients with colon cancer UICC stage I-III were included from two institutions in Denmark from February 2015 to January 2016. In vivo sentinel node mapping with indocyanine green during laparoscopy and ex vivo sentinel node mapping with methylene blue were performed in all patients. RESULTS: Twenty-nine patients were included. The in vivo sentinel node mapping was successful in 19 cases, and ex vivo sentinel node mapping was successful in 13 cases. In seven cases, no sentinel nodes were identified. A total of 51 sentinel nodes were identified, only one of these where identified by both techniques (2.0%). In vivo sentinel node mapping identified 32 sentinel nodes, while 20 sentinel nodes were identified by ex vivo sentinel node mapping. Lymph node metastases were found in 10 patients, and only two had metastases in a sentinel node. CONCLUSION: Placing a deposit in relation to the tumor by indocyanine green in vivo or of methylene blue ex vivo could only identify sentinel lymph nodes in a small group of patients.