A comprehensive appraisal of HER2 heterogeneity in HER2-amplified and HER2-low colorectal cancer.

BACKGROUND: This study aimed to elucidate the clinicopathological and molecular features of HER2-amplified and HER2-low colorectal cancers (CRCs). We also characterised HER2 expression statuses in CRCs focusing on their intratumoral heterogeneity and alterations in metastatic lesions to establish practical HER2 status assessment. METHODS: We evaluated 1009 CRCs for HER2 expression and HER2 amplification by immunohistochemistry and FISH, respectively, and correlated the results to clinicopathological and molecular data. For HER2-positive tumours, HER2 expression in metastatic lesions was also assessed. RESULTS: Twenty-five HER2-amplified (2.5%) and 46 HER2-low tumours (4.6%) were identified. HER2-amplified tumours consistently lacked a mucinous component and HER2-low tumours tended to be in the right colon, but no other clinicopathological features were noted. KRAS, NRAS or BRAF mutations were detected in only two HER2-amplified tumours (8%), whereas 23 HER2-low tumours (50%) had one of these mutations. Most HER2-amplified and HER2-low tumours showed a homogeneous or mosaic HER2 expression pattern and a clustered heterogeneous expression pattern was rather rare. HER2 expression was maintained in most metastatic lesions in both HER2-amplified (93%) and HER2-low tumours (81%). CONCLUSIONS: These results suggest that biopsy-based assessment of primary lesions is appropriate for the identification of CRC patients eligible for systemic HER2-targeted therapy.

Characteristics of anal canal squamous cell carcinoma as an HPV-associated cancer in Japan.

The definition of the anal canal was revised in the TNM classification (8th edition). The Japanese Society for Cancer of the Colon and Rectum (JSCCR) conducted a retrospective multi-institutional study to clarify the characteristics of anal canal cancer (ACC) in Japan. The diagnoses of 1781 patients treated for ACC were squamous cell carcimoma (SCC; n = 428; 24.0%), adenosquamous cell carcinoma (n = 7; 0.4%), and adenocarcinoma (n = 1260; 70.7%). Anal carcinoma is associated with human papillomavirus (HPV) infection and is risk factor for anal SCC. Among 40 cases analyzed at Takano Hospital and 47 cases analyzed at National Cancer Center Hospital, 34 cases (85.0%) and 40 cases (85.1%), respectively were infected with HPV; HPV-16 was the most common genotype (79.4% and 82.5%). In the JSCCR retrospective multi-institutional study, the prognosis analysis by stage was performed for anal SCC cases (202 cases treated by CRT and 91 cases treated by surgery). The 5-year overall survival (OS) rates by stage did not differ between the two treatment groups to a statistically significant extent. Regarding the results of cancer treatment of patients who underwent HPV infection tests, although the 5-year OS rates by stage did not differ to a statistically significant extent due to the small number of cases, HPV-positive patients had better survival. While an HPV vaccine for anal canal SCC has already been approved internationally, HPV vaccination has already been implemented in Japan as a national immunization program for young women but not for men at present. An HPV vaccination for men is urgently needed.

Clinical impact of genetic alterations of CTNNB1 in patients with grade 3 endometrial endometrioid carcinoma.

To identify prognostic factors in patients with grade 3 (high-grade) endometrial endometrioid carcinoma, we evaluated the spectrum of genomic alterations and examined whether previously reported molecular subtypes of endometrial carcinoma were adapted to clinical outcome prediction. Seventy-five Japanese patients with grade 3 endometrial endometrioid carcinoma, who underwent a potentially curative resection procedure between 1997 and 2018 at the National Cancer Center Hospital, were included. We classified the patients into four risk groups of the disease based on the Proactive Molecular Risk Classifier for Endometrial Cancer. Genomic alterations in PTEN, ARID1A, TP53, and PIK3CA were detected in more than 30% of the patients. Overall survival and recurrence-free survival of patients with genomic alterations in CTNNB1 were poorer than those of patients with wild-type CTNNB1 (p = 0.006 and p = 0.004, respectively). Compared with that of alterations prevalent in Caucasians, the frequency of genomic alterations in POLE and TP53 was higher in our study than in The Cancer Genome Atlas dataset (p = 0.01 and p = 0.01, respectively). The tendency for recurrence-free survival in the POLE exonuclease domain mutation group was better than that in the TP53 mutation and mismatch repair-deficient groups (p = 0.08 and p = 0.07, respectively), consistent with the Proactive Molecular Risk Classifier for Endometrial Cancer risk classifier definition. The CTNNB1 mutation is a potential novel biomarker for the prognosis of patients with grade 3 endometrial endometrioid carcinoma, and prognosis classification using Proactive Molecular Risk Classifier for Endometrial Cancer may help screen Japanese patients with the disease.

Clinicopathological and molecular characteristics of RSPO fusion-positive colorectal cancer.

BACKGROUND: RSPO fusions that lead to WNT pathway activation are potential therapeutic targets in colorectal cancer (CRC), but their clinicopathological significance remains unclear. METHODS: We screened 1019 CRCs for RSPO fusions using multiplex reverse transcription-PCR. The RSPO fusion-positive tumours were subjected to whole-exome sequencing (WES). RESULTS: Our analysis identified 29 CRCs with RSPO fusions (2.8%), consisting of five with an EIF3E-RSPO2 fusion and 24 with PTPRK-RSPO3 fusions. The patients were 17 women and 12 men. Thirteen tumours (45%) were right-sided. Histologically, approximately half of the tumours (13/29, 45%) had a focal or extensive mucinous component that was significantly more frequent than the RSPO fusion-negative tumours (13%; P = 8.1 × 10-7). Four tumours (14%) were mismatch repair-deficient. WES identified KRAS, BRAF, and NRAS mutations in a total of 27 tumours (93%). In contrast, pathogenic mutations in major WNT pathway genes, such as APC, CTNNB1 and RNF43, were absent. RSPO fusion status did not have a statistically significant influence on the overall or recurrence-free survival. These clinicopathological and genetic features were also confirmed in a pooled analysis of previous studies. CONCLUSION: RSPO fusion-positive CRCs constitute a rare subgroup of CRCs with several characteristic clinicopathological and genetic features.

ARID1A deficiency in EBV-positive gastric cancer is partially regulated by EBV-encoded miRNAs, but not by DNA promotor hypermethylation.

AT-rich interactive domain 1A (ARID1A), which is a tumor suppressor gene, is frequently mutated in Epstein-Barr virus-positive gastric cancer [EBV (+) GC]. While most ARID1A mutations in GC are truncating mutations, leading to loss of ARID1A protein expression, epigenetic modifications appear to contribute to ARID1A deficiency in EBV (+) GC harboring wild-type ARID1A. Based on the significant role of epigenetic modifications in EBV (+) GC that contributes to ARID1A deficiency, the methylation status of ARID1A was evaluated in EBV-infected cells and GC patients using a publicly available microarray and the Cancer Genome Atlas (TCGA) database. EBV-encoded miRNAs that potentially target ARID1A were identified as an additional epigenetic modulator by computational prediction. In vitro experiments were conducted to evaluate how EBV-encoded miRNAs affected ARID1A mRNA and protein levels. In clinical GC samples, the expression of predicted miRNAs and ARID1A and the mutation status of ARID1A was evaluated. As results, ARID1A was not hypermethylated in EBV (+) GC samples or EBV-infected GC cells. EBV infection did not alter ARID1A mRNA levels, suggesting that ARID1A protein deficiency was caused by post-transcriptional gene silencing in ARID1A-WT EBV (+) GC. Overexpression of miR-BART11-3p and miR-BART12, which were identified as miRNAs that potentially bind ARID1A, suppressed ARID1A protein expression in MKN7 and NCI-N87 cells. Highly expressed miR-BART11-3p and miR-BART12 were correlated with decreased ARID1A levels in GC tumors which did not harbor ARID1A mutations. The present findings revealed that ARID1A expression was epigenetically regulated by miR-BART11-3p and miR-BART12 in EBV (+) GC.

NTRK fusion-positive colorectal cancer in Japanese population.

ALK, ROS1 and NTRK fusions are involved in the tumorigenesis of various organs, including colorectal cancer. This study aims to clarify the prevalence of these fusions in colorectal cancer in the Japanese population. Immunohistochemical analysis of 1012 specimens of colorectal cancer revealed two NTRK-positive cases (0.2%) whereas no ALK- or ROS1-positive cases were identified. Reverse transcription polymerase chain reaction (RT-PCR) detected an LMNA-NTRK1 fusion in a case of adenosquamous carcinoma and a TPM3-NTRK1 fusion in a case of tubular adenocarcinoma. Both NTRK1 fusion-positive cases lacked activating mutations in KRAS and BRAF and were mismatch repair-deficient with loss of MLH1 and PMS2 expression and MLH1 promoter methylation. Our results show that receptor tyrosine kinase fusions are rare but present in colorectal cancers in Japanese patients, with a prevalence similar to that reported in other countries.

Genomic alterations in STK11 can predict clinical outcomes in cervical cancer patients.

OBJECTIVE: Cervical cancer is the fourth most common cause of cancer-related deaths in Asian women, due to its poor prognosis. This study aimed to decipher genomic alteration profiles of a cohort of Japanese cervical cancer patients to understand why certain patients benefited from molecular targeted therapies and their prognostic significance. METHODS: During 2008-2018, 154 cervical cancer patients underwent a potentially curative resection procedure at the National Cancer Center Hospital. Genomic DNA samples were analyzed using Ion AmpliSeq™ Cancer Hotspot Panel v2. Alterations in the copy number of PIK3CA, ERBB2, PTEN, and STK11 were detected using the TaqMan assay. HPV-positive results were confirmed by genomic testing and in situ hybridization assay. RESULTS: The frequency of genomic alterations in PIK3CA (36%), STK11 (16%), PTEN (11%), TP53 (11%), and KRAS (8%) was >5%. KRAS mutations were preferentially detected in patients with adenocarcinomas, and the frequency of PIK3CA mutations in patients with squamous cell carcinomas was higher than that in patients with other histological cancer types. HPV-positive results were observed in 139/154 (90.3%) patients, and TP53 mutants were detected in HPV-negative specimens. In this study, the overall survival of patients with genomic alterations in STK11 was worse than in patients with wild-type STK11 (hazard ratio = 10.6, P = 0.0079) and TCGA dataset (hazard ratio = 2.46, P = 0.029). CONCLUSIONS: More than one-third of Japanese cervical cancer patients exhibit mutations targeted by molecular targeted therapies. We have proposed the prognostic value of STK11 genomic alterations.

A novel volume-reduced CT colonography regimen using hypertonic laxative (polyethylene glycol with ascorbic acid): randomized controlled trial.

OBJECTIVES: The aim of this study is to investigate the feasibility of bowel preparation using a hypertonic laxative (polyethylene glycol with ascorbic acid, PEG + Asc) for CT colonography (CTC) and to examine the volume limit of laxative. METHODS: In one institution, patients who met the indications for CTC were enrolled and randomly assigned to CTC with regimen A (800 ml PEG + Asc), B (600 ml PEG + Asc), or C (400 ml PEG + Asc). Sodium diatrizoate was given orally for fecal tagging. On the previous day, patients ate low-residue meals and took the assigned lavage solution after dinner. A reader blinded to the preparation graded residual stool/fluid and fecal tagging quality in six segments of the colorectum. The primary outcome was a proportion of colon segments without stool. One hundred twenty segments in 20 patients with each regimen were needed to show a non-inferiority margin of 15%, assuming 85% of no stool. RESULTS: A total of 360 segments in 60 patients were analyzed. There were 83% of segments with no stool in regimen A, 89% in regimen B, and 88% in regimen C. Using the delta method, the 95% confidence interval of the risk difference (6.7%) between regimens A and B was - 2.2% to 15.6%, and the risk difference (5.0%) between regimens A and C was - 4.1% to 14%, both within the non-inferiority margin. Residual fluid and fecal tagging quality were also within the non-inferiority margin. No adverse events occurred. CONCLUSIONS: A novel CTC regimen using hypertonic laxative demonstrated optimal colon cleansing effectiveness even with the lowest volume of laxative (UMIN000022851). KEY POINTS: • A novel CTC regimen using a hypertonic laxative is feasible. • The lowest volume of laxative provides excellent colon imaging. • However, the lowest volume of laxative did not improve patient acceptance.

[Two Cases of Advanced Colorectal Cancer Achieving Complete Response by FOLFOXIRI plus Bevacizumab-A Case Report].

We report 2 cases of advanced colorectal cancer achieving complete response by FOLFOXIRI plus bevacizumab. Case 1 was a 65-year-old male diagnosed with descending colon cancer with multiple liver metastases. Six courses of FOLFOXIRI plus bevacizumab were administered after laparoscopic-assisted left hemicolectomy. Ten partial hepatectomies and 1 radiofrequency ablation were performed as the liver metastases resolved. A pathological complete response was confirmed. Adjuvant chemotherapy was not administered, and recurrence-free survival was 21 months after hepatectomy. Case 2 was a 77-yearold male diagnosed with rectal cancer invading the pelvic wall and sacral foramen with bilateral lateral lymph node metastasis. Additionally, there was a cancer embolism in the right internal iliac vein. Six courses of FOLFOXIRI plus bevacizumab were administered, and the cancer tissue was absent on subsequent CT and MRI. The cancer was scarred by colonoscopy, and the biopsy showed no malignant cells. Six courses of FOLFIRI plus panitumumab were administered as second-line chemotherapy, and the patient survived without any recurrence after 12 months from initiation of chemotherapy.

[Curative Transanal Resection after Neoadjuvant Chemotherapy for Lower Rectal Cancer-A Case Report].

A 53-year-old woman was referred to our hospital with melena. Examinations revealed advanced rectal cancer involving the anal canal with invasion of the left-sided levator ani muscle. Neoadjuvant chemotherapy was administered to preserve anal function. A first course of capecitabine and oxaliplatin(CapeOX)plus bevacizumab was administered. CapeOX plus panitumumab was administered from the 2nd to the 8th courses after confirming the absence of RAS mutation. Endoscopy and computed tomography confirmed the disappearance of the tumor after completion of the chemotherapy. A biopsy of the scar tissue revealed no cancer cells. However, diffusion weighted-magnetic resonance imaging(MRI-DWI)revealed a suspected residual tumor. To determine the subsequent treatment, a transanal resection was performed. No carcinoma was identified in the specimen. Thus, additional surgical treatment and adjuvant chemotherapy were not administered. The patient was followed-up over 2.5 years post local resection and showed no recurrence.

Histological Comparison of Cold versus Hot Snare Resections of the Colorectal Mucosa.

BACKGROUND: Delayed postpolypectomy bleeding occurs more frequently after hot resection than after cold resection. OBJECTIVE: To elucidate the underlying mechanism, we performed a histological comparison of tissue after cold and hot snare resections. DESIGN: This is a prospective study, registered in the University Hospital Medical Information Network (UMIN000020104). SETTING: This study was conducted at Aizu Medical Center, Fukushima Medical University, Japan. PATIENTS: Fifteen patients scheduled to undergo resection of colorectal cancer were enrolled. INTERVENTION: On the day before surgery, 2 mucosal resections (hot and cold) of normal mucosa were performed on each patient using the same snare without saline injection. The difference was only the application of electrocautery or not. Resection sites were placed close to the cancer to be included in the surgical specimen. MAIN OUTCOME MEASURES: The primary outcome measure was the depth of destruction. Secondary outcome measures included the width of destruction, depth of the remaining submucosa, and number of vessels remaining at the resection sites. The number and diameter of vessels in undamaged submucosa were also evaluated. RESULTS: All cold resections were limited to the shallow submucosa, whereas 60% of hot resections advanced to the deep submucosa and 20% to the muscularis propria (p < 0.001). There was no significant difference in the width of destruction. The number of remaining large vessels after hot resections trended toward fewer (p = 0.15) with a decreased depth of remaining submucosa (p = 0.007). In the deep submucosa, the vessel diameter was larger (p < 0.001) and the number of large vessels was greater (p = 0.018). LIMITATIONS: Histological assessment was not blinded to the 2 reviewers. Normal mucosa was used instead of adenomatous tissue. CONCLUSIONS: Hot resection caused damage to deeper layers involving more large vessels. This may explain the mechanism for the reduced incidence of hemorrhage after cold snare polypectomy. See Video Abstract at http://links.lww.com/DCR/A631.

Efficacy of transanal tube for prevention of anastomotic leakage following laparoscopic low anterior resection for rectal cancers: a retrospective cohort study in a single institution.

BACKGROUND: Anastomotic leakage is one of the most serious complications following laparoscopic low anterior resection (LAR) for rectal cancers. The purpose of this study was to investigate whether transanal tube placement can reduce anastomotic leakage following laparoscopic LAR. METHODS: Retrospective assessment was performed on 205 patients with rectal cancers who underwent laparoscopic LAR. A transanal tube was placed after anastomosis in 96 patients (group A). Another 109 patients were operated on without a transanal tube (group B). Clinicopathological and operative variables, the frequencies of anastomotic leakage and re-operation after leakage were investigated. RESULTS: Patient age, gender, body mass index, tumor size, Dukes' stage, intra-operative blood loss, and the rate of left colic artery preservation were comparable between the two groups. Tumor location was lower and operative time was significantly longer in group A than group B (p < 0.001). Overall rate of leakage was 9.3 % (19/205). The frequency of leakage was 4.2 % (4/96) in group A and was 13.8 % (15/109) in group B. The rate of leakage was significantly lower in group A (p < 0.05). Furthermore, the re-operation rate for symptomatic anastomotic leakage was 0 % (0/4) in group A, while in contrast it was 73.3 % (10/15) in group B. The rate of re-operation was lower in group A than group B (p < 0.05) and all cases with symptomatic leakage in group A were cured by conservative treatment. CONCLUSIONS: Transanal tube placement was effective for prevention of anastomotic leakage following laparoscopic LAR and avoiding re-operation after symptomatic leakage.

Transverse colon cancer occurring at a colostomy site 35 years after colostomy: a case report.

BACKGROUND: Carcinomas occurring at colostomy sites are rare, and most of these are metachronous colorectal cancers. The median time between colostomy and development of a carcinoma at a colostomy site is 22 years, which exceeds the length of the recommended follow-up period. We report a rare case of a carcinoma of the transverse colon occurring at a colostomy site in a patient without a history of colorectal cancer. CASE REPORT: An 89-year-old woman presented with a tumor occurring at a colostomy site. Thirty-five years previously, she had undergone a transverse loop colostomy for an iatrogenic colon perforation that occurred during left ureteral lithotomy. Upon physical examination, the patient had a hard nodule measuring 3 cm at the colostomy site. A biopsy of the nodule suggested adenocarcinoma, and the preoperative diagnosis was transverse colon cancer. A laparotomy was performed via a peristomal incision with 5-mm skin margins, and the tumor was covered by a surgical glove to avoid any tumor seeding. The colon was separated from the tumor by 5-cm margins, and the specimen was removed en bloc. An end colostomy was constructed to a new site on the right side of the abdomen. The deficit in the abdominal wall was repaired, and the skin was closed via a purse-string suture. The final diagnosis of the stoma tumor was transverse colon cancer (T2, N0, M0, stage I). One year and five months after surgery, there was no evidence of recurrence. CONCLUSIONS: The occurrence of carcinomas at colostomy sites in patients without a history of colorectal cancer is rare. It is important to train ostomates to monitor the stoma for possible tumor recurrence.

Evaluation of the safety and efficacy of esophagojejunostomy after totally laparoscopic total gastrectomy using a trans-orally inserted anvil: a single-center comparative study.

BACKGROUND: Although laparoscopic surgery is frequently performed for the treatment of gastric cancer, laparoscopic total gastrectomy is not widely performed because of its technical difficulty. Since December 2007 we have performed esophagojejunostomy after totally laparoscopic total gastrectomy (TLTG) in more than 110 cases in our institution by using a circular stapler with a trans-orally inserted anvil. We performed a single-center comparative study to evaluate the safety and efficacy of esophagojejunostomy using a trans-orally inserted anvil in patients who underwent TLTG for the treatment of gastric cancer. METHODS: In the present study, we examined 329 patients with gastric cancer who underwent esophagojejunostomy using a circular stapler after total gastrectomy. Data on the clinicopathological features, operative time, amount of intraoperative blood loss, and incidence of anastomosis-related complications among the surgical groups were obtained by reviewing the medical records, which were then analyzed. RESULTS: Approximately 67% of the patients were men, and the average patient age was 64.0 years (range 26-93 years). In addition, 166 (50.5%) and 163 (49.5%) patients underwent open and laparoscopic surgery, respectively. Leakage following esophagojejunostomy was noted in 7 (4.2%) of 166 patients who underwent total gastrectomy with open laparotomy, and 0 of 46 patients who underwent laparoscopic-assisted total gastrectomy (LATG). However, only 2 (1.7%) of 117 patients who underwent TLTG using a trans-orally inserted anvil exhibited leakage following esophagojejunostomy. Anastomotic stenosis of the esophagojejunostomy was observed in 5 (3.0%) of 166 patients who underwent total gastrectomy with open laparotomy, 2 (4.3%) of 46 patients who underwent LATG, and 2 (1.7%) of 117 patients who underwent TLTG using a trans-orally inserted anvil. CONCLUSIONS: We believe that esophagojejunostomy using a trans-orally inserted anvil after TLTG for gastric cancer is a safe and useful surgical procedure.

Malignant peritoneal mesothelioma with lymph node metastasis that originated in the transverse colon.

BACKGROUND: We report an extremely rare case of resection of localized biphasic malignant peritoneal mesothelioma of the transverse colon. CASE REPORT: Computed tomography and magnetic resonance imaging in a 72-year-old man showed a tumor with enhanced borders consistent with the transverse colon. Colonoscopy showed ulcerative lesions in the transverse colon, but histological examination showed no malignancy. A gastrointestinal stromal tumor was strongly suspected, so an extended right hemicolectomy was performed. Histopathological examination showed that the tumor was a localized malignant peritoneal mesothelioma of the transverse colon. The patient did not receive postoperative chemotherapy and died 18 months after surgery. CONCLUSIONS: The number of patients with malignant mesotheliomas is predicted to increase in the future both in Japan and in western countries. We report this case due to its probable usefulness in future studies pertaining to the diagnosis and treatment of malignant mesotheliomas.

Hybrid laparoscopic complete untinatectomy of pancreas by Shuriken shaped umbilicoplasty with sliding windows method.

In this study, we demonstrated the complete resection of untinate process that was performed by the hybrid laparoscopic surgery using our original new technique of Shuriken shaped umbilicoplasty with sliding window`s method. A 70-year-old weman was hospitalized for surgery of intraductal papillary mucinous neoplasm located in the uncinate process of pancreas. Under general anesthesia, a Shuriken shaped umbilical skin incision was made by 7 cm in horizontal and 4cm longitudinal width with 3cm round skin incision. The intermediate skin between outside and inside skin incision was removed. Subcutaneous tissue around the umbilicus and the upper abdominal subcutaneous region was dissected, and the 8cm of upper abdominal minilaparotomy was performed. The complete resection of untinate process was performed by hybrid laparoscopic procedure with the hand-assisted or the laparo-assisted manner. The umbilicoplasty of only 3cm round skin wound was made by the reefing of subcutaneous suture with 5-0 absorbable suture. The patient suffered from pancreas leakage from pancreas stump, however it was recovered spontaneously. Our new procedure could be used for PD, DP, and Major hepatectomy with the hybrid laparoscopic procedure. It might be considered that our method is good for both cosmetic and safety benefits in HPB surgery.

[A case of severe enteritis induced by adjuvant chemotherapy for colon cancer].

A 77-year-old man underwent surgery for sigmoid colon cancer. He was diagnosed with Stage IIIa colon cancer; there- fore, we initiated oral administration of adjuvant chemotherapy comprising uracil/tegafur(UFT)plus Leucovorin(LV). However, chemotherapy was stopped after 21 days because of fatigue and diarrhea. He recovered after 3 weeks, and we administered the same regimen with a dose reduction. However, he again experienced fatigue and diarrhea after 20 days; therefore, chemotherapy was discontinued. Subsequently, he was hospitalized 8 times for conditions such as diarrhea, hypoalbuminemia, and fever. Computed tomography revealed thickening of the transverse colonic wall and colonoscopy revealed colitis, which we believe was induced by UFT plus LV. Twelve months after the last chemotherapy session, he was diagnosed with Clostridium difficile colitis. Therefore, we initiated the oral administration of vancomycin, which resulted in rapid recovery from colitis. However, he developed liver metastasis and died 29 months after the initiation of chemotherapy. We believe that this severe case of intractable colitis was caused by UFT plus LV. Therefore, we report this case with a review of the literature on enteritis induced by fluorouracil-based anticancer agents in Japan.

Non-classical Monocytes Enhance the Efficacy of Immune Checkpoint Inhibitors on Colon Cancer in a Syngeneic Mouse Model.

BACKGROUND/AIM: The response rate to immune checkpoint inhibitors (ICIs) is approximately 10%-30% and only in a few cancer types. In the present study, we determined whether non-classical monocytes (NCMs) could enhance ICI efficacy in colon cancer using a syngeneic mouse model. MATERIALS AND METHODS: The MC38 C57BL/6 mouse colon cancer model was used. Cells collected from the bone marrow of C57BL/6 mice were cultured, and NCMs were fractionated by cell sorting and administered via the tail veins to the mice implanted with MC38 cells. The anti-mouse PD-L1 antibody was administered three times, and tumor volume and overall survival were observed. RESULTS: More tumors were eradicated and more complete response occurred, after cotreatment with ICIs and NCMs than after treatment with ICIs alone. Moreover, no efficacy was observed when NCMs were administered alone. CONCLUSION: NCMs enhance ICI efficacy. The underlying mechanisms and clinical applications will be studied in the future.

Comparison of clinicopathological and genomic profiles in anal squamous cell carcinoma between Japanese and Caucasian cohorts.

Anal squamous cell carcinoma (ASCC) is a rare tumor of the gastrointestinal tract. We aimed to compare the genetic backgrounds and their effect on clinical outcomes between Japanese and Caucasian patients with ASCC. Forty-one patients diagnosed with ASCC at the National Cancer Center Hospital were enrolled and evaluated for clinicopathological features, human papillomavirus (HPV) infection, HPV genotypes, p16 expression, PD-L1, and association of p16 status with the efficacy of concurrent chemoradiotherapy (CCRT). Target sequencing for hotspot mutations in 50 cancer-related genes was performed using genomic DNA from 30 available samples. Of 41 patients, 34 were HPV-positive (among them, HPV 16 was predominant; 73.2%); 38 patients were p16-positive (92.7%); and 39 patients received CCRT, of whom 36 were p16-positive and three p16-negative. p16-positive patients showed better complete response than p16-negative patients. Among 28 samples, 15 showed mutations in PIK3CA, FBXW7, ABL1, TP53, and PTEN; no difference in mutation profiles between the Japanese and Caucasian cohorts was observed. Actionable mutations were detected in both Japanese and Caucasian patients with ASCC. Genetic backgrounds, such as the HPV 16 genotype and PIK3CA mutations, were common regardless of ethnicity. p16 status may be a prognostic biomarker for CCRT in Japanese patients with ASCC.

Monocyte subsets associated with the efficacy of anti­PD­1 antibody monotherapy.

Immune checkpoint inhibitors (ICIs) are among the most notable advances in cancer immunotherapy; however, reliable biomarkers for the efficacy of ICIs are yet to be reported. Programmed death (PD)-ligand 1 (L1)-expressing CD14+ monocytes are associated with shorter overall survival (OS) time in patients with cancer treated with anti-PD-1 antibodies. The present study focused on the classification of monocytes into three subsets: Classical, intermediate and non-classical. A total of 44 patients with different types of cancer treated with anti-PD-1 monotherapy (pembrolizumab or nivolumab) were enrolled in the present study. The percentage of each monocyte subset was investigated, and the percentage of cells expressing PD-L1 or PD-1 within each of the three subsets was further analyzed. Higher pretreatment classical monocyte percentages were correlated with shorter OS (r=-0.32; P=0.032), whereas higher non-classical monocyte percentages were correlated with a favorable OS (r=0.39; P=0.0083). PD-L1-expressing classical monocytes accounted for a higher percentage of the total monocytes than non-classical monocytes with PD-L1 expression. In patients with non-small cell lung cancer (NSCLC), a higher percentage of PD-L1-expressing classical monocytes was correlated with shorter OS (r=-0.60; P=0.012), which is similar to the observation for the whole patient cohort. Comparatively, higher percentages of non-classical monocytes expressing PD-L1 were significantly associated with better OS, especially in patients with NSCLC (r=0.60; P=0.010). Moreover, a higher percentage of non-classical monocytes contributed to prolonged progression-free survival in patients with NSCLC (r=0.50; P=0.042), with similar results for PD-L1-expressing non-classical monocytes. The results suggested that the percentage of monocyte subsets in patients with cancer before anti-PD-1 monotherapy may predict the treatment efficacy and prognosis. Furthermore, more classical monocytes and fewer non-classical monocytes, especially those expressing PD-L1, are involved in shortening OS time, which may indicate the poor efficiency of anti-PD-1 treatment approaches.