Spatiotemporal commonality of the TCR repertoire in a T-cell memory murine model and in metastatic human colorectal cancer.

Immune checkpoint inhibitors (ICIs) have shown superior clinical responses and significantly prolong overall survival (OS) for many types of cancer. However, some patients exhibit long-term OS, whereas others do not respond to ICI therapy at all. To develop more effective and long-lasting ICI therapy, understanding the host immune response to tumors and the development of biomarkers are imperative. In this study, we established an MC38 immunological memory mouse model by administering an anti-PD-L1 antibody and evaluating the detailed characteristics of the immune microenvironment including the T cell receptor (TCR) repertoire. In addition, we found that the memory mouse can be established by surgical resection of residual tumor following anti-PD-L1 antibody treatment with a success rate of > 40%. In this model, specific depletion of CD8 T cells revealed that they were responsible for the rejection of reinoculated MC38 cells. Analysis of the tumor microenvironment (TME) of memory mice using RNA-seq and flow cytometry revealed that memory mice had a quick and robust immune response to MC38 cells compared with naïve mice. A TCR repertoire analysis indicated that T cells with a specific TCR repertoire were expanded in the TME, systemically distributed, and preserved in the host for a long time period. We also identified shared TCR clonotypes between serially resected tumors in patients with colorectal cancer (CRC). Our results suggest that memory T cells are widely preserved in patients with CRC, and the MC38 memory model is potentially useful for the analysis of systemic memory T-cell behavior.

Identification of T Cell Receptors Targeting a Neoantigen Derived from Recurrently Mutated FGFR3.

Immunotherapies, including immune checkpoint blockades, play a critically important role in cancer treatments. For immunotherapies, neoantigens, which are generated by somatic mutations in cancer cells, are thought to be good targets due to their tumor specificity. Because neoantigens are unique in individual cancers, it is challenging to develop personalized immunotherapy targeting neoantigens. In this study, we screened "shared neoantigens", which are specific types of neoantigens derived from mutations observed commonly in a subset of cancer patients. Using exome sequencing data in the Cancer Genome Atlas (TCGA), we predicted shared neoantigen peptides and performed in vitro screening of shared neoantigen-reactive CD8+ T cells using peripheral blood from healthy donors. We examined the functional activity of neoantigen-specific T cell receptors (TCRs) by generating TCR-engineered T cells. Among the predicted shared neoantigens from TCGA data, we found that the mutated FGFR3Y373C peptide induced antigen-specific CD8+ T cells from the donor with HLA-A*02:06 via an ELISPOT assay. Subsequently, we obtained FGFR3Y373C-specific CD8+ T cell clones and identified two different sets of TCRs specifically reactive to FGFR3Y373C. We found that the TCR-engineered T cells expressing FGFR3Y373C-specific TCRs recognized the mutated FGFR3Y373C peptide but not the corresponding wild-type peptide. These two FGFR3Y373C-specific TCR-engineered T cells showed cytotoxic activity against mutated FGFR3Y373C-loaded cells. These results imply the possibility of strategies of immunotherapies targeting shared neoantigens, including cancer vaccines and TCR-engineered T cell therapies.

Lymphocytes in tumor-draining lymph nodes co-cultured with autologous tumor cells for adoptive cell therapy.

BACKGROUND: Tumor-draining lymph nodes (TDLNs) are primary sites, where anti-tumor lymphocytes are primed to tumor-specific antigens and play pivotal roles in immune responses against tumors. Although adoptive cell therapy (ACT) using lymphocytes isolated from TDLNs were reported, characterization of immune activity of lymphocytes in TDLNs to tumor cells was not comprehensively performed. Here, we demonstrate TDLNs to have very high potential as cell sources for immunotherapy. METHODS: Lymphocytes from TDLNs resected during surgical operation were cultured with autologous-tumor cells for 2 weeks and evaluated tumor-reactivity by IFNγ ELISPOT assay. We investigated the commonality of T cell receptor (TCR) clonotypes expanded by the co-culture with tumor cells with those of tumor infiltrating lymphocytes (TILs). RESULTS: We found that that TCR clonotypes of PD-1-expressing CD8+ T cells in lymph nodes commonly shared with those of TILs in primary tumors and lymphocytes having tumor-reactivity and TCR clonotypes shared with TILs could be induced from non-metastatic lymph nodes when they were co-cultured with autologous tumor cells. CONCLUSION: Our results imply that tumor-reactive effector T cells were present even in pathologically non-metastatic lymph nodes and could be expanded in vitro in the presence of autologous tumor cells and possibly be applied for ACT.

Laparoscopic surgery for colovesical fistula associated with sigmoid colon diverticulitis: a review of 39 cases.

OBJECTIVES: Colonic diverticular disease is widespread in Western countries and its associated with aging. In Japan, diverticulitis and colovesical fistula are also occurring more frequently. Colonic resection for diverticula-related fistulas is frequently technically demanding because of associated acute or chronic inflammation. We evaluated the safety and efficacy of a standardized laparoscopic procedure. METHODS: Data from 39 consecutive patients who had undergone laparoscopic surgery for colovesical fistula between October 2006 and August 2017 were retrospectively reviewed. RESULTS: The patients' median age was 60 years and comprised 35 men and four women. Sigmoidectomy was performed in 33 patients, Hartmann's procedure in four, and anterior resection in two. The median operative time was 203 minutes and estimated blood loss 15 mL. There were no intraoperative complications or conversion to open surgery. No patients required bladder repair; three had minor postoperative complications, and none had recurrent diverticulitis or fistula at a mean follow-up of 5.1 years. CONCLUSIONS: The magnified vision and minimal invasiveness make a laparoscopic approach the ideal means of managing colovesical fistula. To our knowledge, this is the largest study of colovesical fistula managed by a standardized laparoscopic procedure.

Laparoscopic treatment of rectal cancer and lateral pelvic lymph node dissection: are they obsolete?

Laparoscopic surgery for rectal cancer offers favorable short-term results without compromising long term oncological outcomes so far, according to the data from major trials. For this reason, it is currently considered as a standard option for rectal cancer surgery. The learning curve of laparoscopic rectal cancer surgery is generally longer compared to colon cancer. Appropriate standardization and training of laparoscopic rectal cancer surgery is required. Several RCTs suggested the potential negative effect on quality of resected specimen, which can increase local recurrence. The long-term outcomes - especially local recurrence rate - of these RCTs are awaited. Lateral pelvic lymph node dissection (LPLND) has a certain effect of reducing local recurrence of rectal cancer even after neoadjuvant radiotherapy. Since LPLND is associated with postoperative morbidity, we should carefully select the candidate to maximize the effect of LPLND and minimize the morbidity caused by LPLND. Recent advancements in imaging study such as CT and MRI enable us to find the suitable candidates for LPLND. The morbidity caused by LPLND could be reduced by minimally invasive surgeries such as laparoscopic surgery and robotic surgery. We have to improve oncological outcomes and reduce morbidity by the multidisciplinary strategy for rectal cancer including total mesorectal excision, neoadjuvant chemoradiotherapy and LPLND together with laparoscopic surgery.

[Multimodality Therapy against the Lateral Lymph Node Recurrence of Rectal Cancer].

BACKGROUND: The local recurrence of rectal cancer classifies 4 types, anterior, posterior, lateral compartment and anastomotic site. This study evaluates outcome of laparoscopic lateral lymph node dissection(LLND)against the lateral lymph node recurrence. METHOD: Five patients were diagnosed as the lateral lymph node recurrence and underwent laparoscopic LLND. We diagnosed the lateral lymph node recurrence by CT, MRI and PET-CT. All cases revealed abnormal uptake on PET-CT. RESULT: The median of age is 63. Three patients are male. About primary tumor, 4 patients had tumor below peritoneal reflection and one patient above it. Two patients received neoadjuvant(chemo)radiotherapy(RT group)and one of them underwent laparoscopic LLND at the first operation. The median period from operation to recurrence was 25 months. Before re-operation, 3 patients received chemotherapy. Pathological assessments confirmed pathological complete response(pCR) in all three cases. The median of operation time and bleeding were 257 min and 0 mL, respectively. No complications, more than Grade III(Clavien-Dindo classification)happened. The median follow-up period from re-operation was 34 months. Four patients have no recurrence and one presents lung metastasis. All 5 patients are alive. CONCLUSION: Laparoscope magnifies various pelvic structures. Therefore we perform operation more exactly and safety. In the case of local recurrence, especially lateral compartment, tumor is easy to invade adjacent structures. Then, it is often difficult to do R0 resection. If we find the recurrence lesions earlier and induce neoadjuvant chemotherapy, we can improve R0 resection rate.

Can laparoscopic appendectomy be safely performed by surgical residents without prior experience of open appendectomy?

BACKGROUND: As laparoscopic surgery has become the mainstream technique for abdominal surgery, it has become difficult for surgical residents to have opportunities to perform open surgery. This study aimed to examine the appropriateness and feasibility of laparoscopic appendectomy performed by surgical trainees who had little experience with open appendectomy or laparoscopic training with animal models. METHODS: We retrospectively reviewed all the records of patients who underwent appendectomy for acute appendicitis from April 2008 to December 2014. Residents were assigned to two levels of seniority: junior residents who had undergone 1-3 years of residency and senior residents who had undergone 4-6 years of residency. Patient characteristics, histopathological results, operative time, blood loss, conversion to open procedure, complications, length of hospital stay, and mortality were compared between the two groups. RESULTS: During the study period, 174 patients with the clinical diagnosis of acute appendicitis underwent laparoscopic appendectomy by junior residents and 90 patients were operated on by senior residents. There were no statistical differences in the characteristics of the patients, conversion rates (0/174 vs. 1/90), median operative times (75 minutes vs. 75 minutes), complication rates (7% vs. 4%), and median lengths of hospital stay (4 days vs. 4 days). CONCLUSION: Laparoscopic appendectomy can be performed safely by surgical residents who had little experience or training with animal models or open appendectomy. In this era of laparoscopic surgery, laparoscopic appendectomy represents an important opportunity for training surgical residents with little experience of open surgery.

[A Case of Bilateral Lymph Node Metastases of Rectal Cancer Treated with Chemotherapy and Surgery].

We present a case of bilateral lymph node metastases of rectal cancer treated with chemotherapy and surgery. The patient was a 65-year-old man with upper rectal cancer. Laparoscopic low anterior resection(LAR)was performed. Pathological findings were tub2>por>muc, pT3, ly2, v3, pN2, pM0. Six months after surgery, the CEA level was elevated. CT and PET-CT confirmed bilateral metastasis to the lymph nodes. Five courses of FOLFOX4 plus bevacizumab were administered, and then, we performed laparoscopic bilateral lymph node dissection. Pathological assessments confirmed scarring and fibrosis, that is, a pathological complete response(pCR)was achieved. Two years and 6 months after surgery, no recurrence was detected. After chemotherapy or chemoradiotherapy, we should perform surgery to prevent local recurrence, especially to the lateral lymph nodes.