Novel Biomarkers for Personalized Cancer Immunotherapy

Cancer immunotherapy has emerged as a novel and effective treatment strategy for several types of cancer. Immune checkpoint inhibitors (ICIs) have recently demonstrated impressive clinical benefit in some advanced cancers. Nonetheless, in the majority of patients, the successful use of ICIs is limited by a low response rate, high treatment cost, and treatment-related toxicity. Therefore, it is necessary to identify predictive and prognostic biomarkers to select the patients who are most likely to benefit from, and respond well to, these therapies. In this review, we summarize the evidence for candidate biomarkers of response to cancer immunotherapy.

Genomic profiles of colorectal carcinoma with liver metastases and newly identified fusion genes

Every year, approximately 1.2 million cases of colorectal carcinoma (CRC) are newly diagnosed worldwide. Although metastases to distant organs are often fatal complications of CRC, little information is known as to how such metastatic lesions are formed. To reveal the genetic profiles for CRC metastasis, we conducted whole‐exome RNA sequencing on CRC tumors with liver metastasis (LM) (group A, n = 12) and clinical stage‐matched larger tumors without LM (group B, n = 16). While the somatic mutation profiles were similar among the primary tumors and LM lesions in group A and the tumors in group B, the A‐to‐C nucleotide change in the context of “AAG” was only enriched in the LM regions in group A, suggesting the presence of a DNA damage process specific to metastasis. Genes already known to be associated with CRC were mutated in all groups at a similar frequency, but we detected somatic nonsynonymous mutations in a total of 707 genes in the LM regions, but not in the tumors without LM. Signaling pathways linked to such “LM‐associated” genes were overrepresented for extracellular matrix‐receptor interaction or focal adhesion. Further, fusions of the ADAP1 (ArfGAP with dual PH domain 1) were newly identified in our cohort (3 out of 28 patients), which activated ARF6, an ADAP1‐substrate. Infrequently, mutated genes may play an important role in metastasis formation of CRC. Additionally, recurrent ADAP1 fusion genes were unexpectedly discovered. As these fusions activate small GTPase, further experiments are warranted to examine their contribution to CRC carcinogenesis.

Establishment of a novel experimental model for muscle-invasive bladder cancer using a dog bladder cancer organoid culture

In human and dogs, bladder cancer (BC) is the most common neoplasm affecting the urinary tract. Dog BC resembles human muscle‐invasive BC in histopathological characteristics and gene expression profiles, and could be an important research model for this disease. Cancer patient‐derived organoid culture can recapitulate organ structures and maintains the gene expression profiles of original tumor tissues. In a previous study, we generated dog prostate cancer organoids using urine samples, however dog BC organoids had never been produced. Therefore we aimed to generate dog BC organoids using urine samples and check their histopathological characteristics, drug sensitivity, and gene expression profiles. Organoids from individual BC dogs were successfully generated, expressed urothelial cell markers (CK7, CK20, and UPK3A) and exhibited tumorigenesis in vivo. In a cell viability assay, the response to combined treatment with a range of anticancer drugs (cisplatin, vinblastine, gemcitabine or piroxicam) was markedly different in each BC organoid. In RNA‐sequencing analysis, expression levels of basal cell markers (CK5 and DSG3) and several novel genes (MMP28,CTSE,CNN3,TFPI2,COL17A1, and AGPAT4) were upregulated in BC organoids compared with normal bladder tissues or two‐dimensional (2D) BC cell lines. These established dog BC organoids might be a useful tool, not only to determine suitable chemotherapy for BC diseased dogs but also to identify novel biomarkers in human muscle‐invasive BC. In the present study, for the 1st time, dog BC organoids were generated and several specifically upregulated organoid genes were identified. Our data suggest that dog BC organoids might become a new tool to provide fresh insights into both dog BC therapy and diagnostic biomarkers.

Abstract 1091: Comparison of TCR repertoires between cancer tissues and lymph nodes in colorectal cancer patients

Tumor draining lymph nodes (TDLNs) are located in the routes of lymphatic drainage from a primary tumor and have the highest metastasis in various types of solid tumors. TDLNs are considered as a tissue to activate the antitumor immunity, where antigen-specific effector T cells are generated and released to the blood stream. These effector T cells then infiltrate into the tumor site and attack cancer cells. However, T cell receptor (TCR) repertoire in TDLNs has not been well characterized. We performed TCR sequencing of cancer tissues, corresponding normal mucosa tissues and a total of 203 regional lymph nodes, including 67 metastasis-positive lymph nodes from 23 colorectal cancer patients with lymph node metastasis. Metastasis-positive lymph nodes showed a significantly lower TCR diversity and shared TCR clones more frequently with primary tumor tissues compared to metastasis-negative TDLNs. Hierarchical clustering and principal component analyses also supported that TCR repertoires in metastasis-positive TDLNs were more similar to primary tumor tissues than metastasis-negative TDLNs. These finding suggest that cancer-reactive T cell clones might expand in the metastasis-positive TDLNs, although we have not tested their reactivity against cancer cells. We are now examining whether the T cells in TDLNs can recognized autologous cancer cells.

Citation Format: Kazuma Kiyotani, Tatsuo Matsuda, Eisaku Miyauchi, Yu-Wen Hsu, Satoshi Nagayama, Makda Zewde, Jae-Hyun Park, Taigo Kato, Makiko Harada, Nobuaki Suzuki, Hiroaki Nagano, Shoichi Hazama, Yusuke Nakamura. Comparison of TCR repertoires between cancer tissues and lymph nodes in colorectal cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1091.

Induction of antigen specific CD8+ T cell infiltration by a novel neoadjuvant vaccine containing HSP70 and GPC3 peptides plus soluble LAG-3 and Poly-IC:LC: Interim results of a Phase I study

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Background: Even with curative resection, the recurrence rate of HCC is still high, and no effective adjuvant therapy is currently available. Our previous Phase I study with novel therapeutic peptides and immune adjuvants demonstrated the safety, antigen specific CTL induction in PBMC and a sign of efficacy (ASCO 2017 Abstract # 3086); thus, we started Phase I study of the same therapy as a perioperative immunotherapy setting in patients with resectable HCC (UMIN000029991). Methods: Two mg each of HLA-A*24:02, 02:01, or 02:06 restricted HSP70- and GPC3-derived peptides, in combination with hLAG-3Ig (1.0 mg) + Poly-IC:LC (1.4 mg) were injected intradermally at four sites of the inguinal and axillary regions every week for 6 weeks before surgery. Patients subsequently received 10 injections of adjuvant immunotherapy over 4 months. Surgical specimens and PBMCs were analyzed by mass cytometry (CyTOF), using 66 antibodies to monitor T cell exhaustion, T cell activation, Effector Treg induction, etc. Tumor specimens were also subjected to immunohistochemical staining of CD3, CD8, PD1, HSP70, and GPC3. The reason for early reporting is the interesting findings at the foci of HCC, and the interim analyses was approved by the Data and Safety Monitoring Committee. Results: Of the 11 screened patients, 5 completed the treatments and were analyzed. We found massive CD8+ T lymphocyte infiltration in the intratumor foci of HCC, which is usually accompanied by peritumoral lymphocytic infiltration. Moreover, the density of lymphocytes was markedly higher in areas of HSP70 or GPC3 antigen expression. One case out of five recurred 5 month after surgery and it showed low CD8+ and PD1+ cell infiltration and high effector Treg (CD4+/CD25+/CD45RA-/FoxP3 +) infiltration. This trend was not observed in PBMC, suggesting the importance of TIL analysis. The high PD1 expression was accompanied by massive intratumoral infiltration of CD8+ lymphocytes. Conclusions: The novel therapeutic peptide and immune adjuvant combination induced sustained immune cell infiltration into tumor microenvironments, especially those presenting target tumor-associated antigens. Our novel immunotherapy may convert cold tumors into hot tumors containing PD1+ lymphocytes. Thus, the combination of this novel strategy with PD (L) 1 antibody is warranted. Clinical trial information: 000029991.

[Combination Therapy of Hepatic Arterial Infusion Chemotherapy and Surgical Resection against Hepatocellular Carcinoma with Portal Vein Tumor Thrombosis]

We have performed a combination therapy of hepatic arterial infusion chemotherapy(HAIC), radiation therapy(RT), and surgical resection for the treatment of hepatocellular carcinoma(HCC)with portal vein tumor thrombosis(PVTT)since 2013. We retrospectively analyzed 36 patients with HCC with PVTT who underwent hepatectomy between 1995 and 2016 to evaluate the clinical outcomes. Ten patients received preoperative HAIC, 7 underwent RT, and 14 received postoperative HAIC. The median survival time(MST)was 19.3 months, and the MST was significantly longer in the patients who underwent curative resection than those in patients who did not. In the non-curative resection group, postoperative HAIC prolonged the survival.

TCR sequencing analysis of cancer tissues and tumor draining lymph nodes in colorectal cancer patients

Tumor draining lymph nodes (TDLNs) are located in the routes of lymphatic drainage from a primary tumor and have the highest risk of metastasis in various types of solid tumors. TDLNs are also considered as a tissue to activate the antitumor immunity, where antigen-specific effector T cells are generated. However, T cell receptor (TCR) repertoires in TDLNs have not been well characterized. We collected 23 colorectal cancer tumors with 203 lymph nodes with/without metastatic cancer cells (67 were metastasis-positive and the remaining 136 were metastasis-negative) and performed TCR sequencing. Metastasis-positive TDLNs showed a significantly lower TCR diversity and shared TCR clonotypes more frequently with primary tumor tissues compared to metastasis-negative TDLNs. Principal component analysis indicated that TDLNs with metastasis showed similar TCR repertoires. These findings suggest that cancer-reactive T cell clones could be enriched in the metastasis-positive TDLNs.

Differential regulation of CpG island methylation within divergent and unidirectional promoters in colorectal cancer

The silencing of tumor suppressor genes by promoter CpG island (CGI) methylation is an important cause of oncogenesis. Silencing of MLH1 and BRCA1, two examples of oncogenic events, results from promoter CGI methylation. Interestingly, both MLH1 and BRCA1 have a divergent promoter, from which another gene on the opposite strand is also transcribed. Although studies have shown that divergent transcription is an important factor in transcriptional regulation, little is known about its implication in aberrant promoter methylation in cancer. In this study, we analyzed the methylation status of CGI in divergent promoters using a recently enriched transcriptome database. We measured the extent of CGI methylation in 119 colorectal cancer (CRC) clinical samples (65 microsatellite instability high [MSI‐H] CRC with CGI methylator phenotype, 28 MSI‐H CRC without CGI methylator phenotype and 26 microsatellite stable CRC) and 21 normal colorectal tissues using Infinium MethylationEPIC BeadChip. We found that CGI within divergent promoters are less frequently methylated than CGI within unidirectional promoters in normal cells. In the genome of CRC cells, CGI within unidirectional promoters are more vulnerable to aberrant methylation than CGI within divergent promoters. In addition, we identified three DNA sequence motifs that correlate with methylated CGI. We also showed that methylated CGI are associated with genes whose expression is low in normal cells. Thus, we here provide fundamental observations regarding the methylation of divergent promoters that are essential for the understanding of carcinogenesis and development of cancer prevention strategies.

[A Case of Locally Re-Recurrent Colon Cancer Involving the Iliac Bone That Underwent Curative Resection]

A 65-year-old woman with cecum cancer underwent laparoscopic right colectomy.After 3 years, she was diagnosed with a local recurrence with small bowel invasion and underwent tumor resection.One year later, she had a re-recurrent lesion involving her right iliac bone.After one year of chemotherapy, a PET-CT showed no other abdominal lesions suggestive of malignancy.She underwent resection of the re-recurrent tumor involving the right iliac bone and R0 resection was achieved. She was able to ambulate postoperatively and returned home.In selected cases, extended surgery including bone resection can be an option for the local recurrence of advanced colon cancer.

[A Case of Distal Pancreatectomy with En Bloc Celiac Axis Resection after Distal Gastrectomy]

A 77-year-old man underwent a follow-up examination after distal gastrectomy. Contrast-enhanced computed tomography revealed a tumor of the pancreatic body and tail that contacted the common hepatic artery/celiac artery. Subsequently, the tumor was diagnosed as a borderline resectable pancreatic cancer. After chemoradiation therapy, the tumor was considered resectable. Preoperative angiography with intraoperative contrast-enhanced ultrasonography and indocyanine green fluorescence imaging confirmed blood flow in the residual stomach. Postoperatively, ischemic necrosis of the residual stomach was not observed. After distal gastrectomy, distal pancreatectomy with en bloc celiac axis resection was performed to safely and curatively address the cancer of the pancreatic body and tail.

[Two Cases of Rupture of Elevated Jejunal Varices after Operation for Hilar Cholangiocarcinoma]

Case 1: A 64-year-old man with a chiefcomplaint ofbloody stools was seen in our hospital. He underwent an extended right lobe resection for hilar cholangiocarcinoma 3 years ago and was in the middle of chemotherapy for multiple metastases. Case 2: A 69-year-old man with a chiefcomplaint ofbloody emesis and stools was seen. He underwent left hepatic trisegmentectomy for hilar cholangiocarcinoma and ligation of the right portal vein for postoperative portal venous thrombus 6 months ago. After careful examination, the patients in both cases were diagnosed with bleeding of the jejunal varices formed at the site ofhepaticojejunostomy. The patient in Case 1 underwent percutaneous transhepatic obliteration ofvarices and the patient in Case 2 underwent transileocolic vein obliteration ofvarices. After hepatobiliary pancreatic surgery with biliary tract reconstruction, we should be aware of ectopic varices during differential diagnosis of gastrointestinal bleeding.

Analysis of UGT1A’s polymorphisms and RAS: RAF mutations based on phase II study of biweekly XELIRI plus bevacizumab as a second-line therapy in patients with metastatic colorectal cancer

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Background: We have previously reported biweekly XELIRI + bevacizumab 10 mg/kg as second-line chemotherapy in metastatic colorectal cancer (mCRC). In this study, we investigated relationships between efficacy/toxicity and biomarkers (polymorphisms of UGT1A’s, somatic mutations of RAS, BRAF and PIK3CA). Methods: Patients with mCRC who had received prior chemotherapy including oxaliplatin based regimen were eligible for this study. Treatment protocol administrated capecitabine 1,000 mg/m2 twice daily from the evening of day 1 to the morning of day 8, intravenous irinotecan 150mg/m2 on day 1, and bevacizumab 10 mg/kg on day 1 every 2 weeks. Results: Between January 2013 and July 2015, 51 patients were enrolled in this study. The patients’ characteristics were as follows (N=51): median age, 66 years (range 41–82); male/female, 29/22; the median PFS was 5.47 months (95% CI, 4.23–7.40 months), the median OS was 13.5months (95%CI, 11.57– 20.23months), and the median TTF was 4.5 months (95%CI, 3.97–6.93 months). The response rate was 16% (95%CI, 7.2–29.1), and the disease control rate was 76% (95%CI, 61.8-86.9). Grade 3 or higher adverse events were mainly febrile neutropenia in two patients and hypertension in 14 patients (28.6%). The patients with UGT1A7 (387G<T) genotype had a trend to suffer from diarrhea ( p=0.089 by Fisher’s exact test). The summary of somatic mutations of cancer was RAS (wild/mutant = 21/23), BRAF (wild/mutant = 39/5), PIK3CA (wild/mutant = 42/0), and MSI (MSS/MSI-H = 42/2). There was no statistical association between efficacy and somatic mutations. The sample size might influenced such the results. Conclusions: In mCRC patients, biweekly XELIRI + bevacizumab 10 mg/kg is effective and feasible as second-line chemotherapy. We found several biomarkers that predict toxicities in this study. Further study is required for predicting the efficacy based on biomarkers using somatic mutations of cancer and germline polymorphisms. Clinical trial information: UMIN000009280.

Efficacy of CapeOX plus Cetuximab Treatment as a First-Line Therapy for Patients with Extended RAS/BRAF/PIK3CA Wild-Type Advanced or Metastatic Colorectal Cancer

Background: Oxaliplatin and capecitabine (CapeOX) combined with cetuximab is rarely used to treat advanced and metastatic colorectal cancer (mCRC). The present study aimed to clarify the clinical benefits of this treatment regimen when used as a first-line therapy in patients with expanded RAS/BRAF/PIK3CA wild-type mCRC, using the data and tumor specimens from two previously published Phase II clinical trials.

Methods: The gene mutation status and clinical data of 102 patients with KRAS wild-type mCRC, who received either of CapeOX + cetuximab or FOLFOX + cetuximab, were analyzed. The primary endpoint was response rate (RR) of CapeOX + cetuximab treatment in patients with extended RAS/BRAF/PIK3CA wild-type mCRC. RR comparisons and maximum tumor size changes between different treatment regimens and gene mutation status were set as key secondary endpoints.

Results: We identified 88 patients with extended RAS/BRAF/PIK3CA wild-type mCRC. Those treated with CapeOX + cetuximab (n = 52) had a 61.5% RR (95% CI, 47.0-74.7%), while those treated with FOLFOX + cetuximab (n = 36) had a 66.7% RR (95% CI, 49.0-81.4%). Patients with any mutation (n = 14) had a 42.9% RR (95% CI, 17.1-71.1%). There were no significant differences between these three groups (P = 0.298). The disease control rate was 86.5% (95% CI, 74.2-94.4%) in the CapeOX + cetuximab group, and 88.9% (95% CI, 73.9-96.9%) in the FOLFOX + cetuximab group. Maximum tumor size changes were largest in patients with wild-type mCRC treated with FOLFOX + cetuximab followed by patients with wild-type mCRC treated with CapeOX + cetuximab, and then by those with any mutation (-63.2%, -52.6%, and -27.3%, respectively; P = 0.035).

Conclusions: Patients with RAS/BRAF/PIK3CA wild-type mCRC had a sufficient RR following first-line treatment with CapeOX + cetuximab. These results suggest that this combination therapy should be considered as a treatment option for patients with advanced mCRC.

Survival benefit of lymph node dissection in surgery for colon cancer in elderly patients: A multicenter propensity score-matched study in Japan

INTRODUCTION

In surgery for elderly patients with colorectal cancer, it is unclear whether radical lymph node (LN) dissection safely offers a survival benefit. The aim of the study was to evaluate the impact of the LN yield in elderly patients undergoing surgery for colorectal cancer.

METHODS

The subjects were selected from a surgical database of 2065 patients aged ≥80 years old who underwent surgery for colorectal cancer at 41 hospitals in Japan between 2003 and 2007. The patients were divided into groups according to the number LN harvested: <12 and ≥12. Propensity scores were subsequently matched to balance the baseline characteristics.

RESULTS

Of the 954 patients initially selected, 331 were in the <12 LN and 623 were in the ≥12 LN group. After cases were matched, 293 patients were allocated to each group, and all covariates were balanced. For short-term outcomes, the time for surgery was longer in the ≥12 LN group, but there was no significant difference in morbidity between the groups. Overall, relapse-free and cancer-specific survival rates were higher in the ≥12 LN group (P = 0.004, 0.001, and 0.02).

CONCLUSIONS

In patients aged ≥80 years old with stage II-III colon cancer, harvesting ≥12 LN provides a survival benefit, and therefore, limited LN dissection is not recommended in these patients.

Efficacy of perioperative immunonutrition in esophageal cancer patients undergoing esophagectomy

OBJECTIVE

Malnutrition is common in patients with esophageal cancer, resulting in increased postoperative complications and mortality. Although preoperative immunonutrition can significantly reduce the incidence of postoperative infectious complications, its effect in patietns with esophageal cancer undergoing esophagectomy remains unclear. The aim of this study was to investigate the effects of perioperative immunonutritional support on the postoperative course and long-term survival of this group of patients.

METHODS

This prospective, randomized study enrolled 40 patients with thoracic esophageal carcinoma undergoing esophagectomy. The patients were divided into two groups and received either immunomodulating enteral nutrition (IMPACT group; IG) or standard enteral nutrition (Ensure group; EG) continuously for 7 d before and 7 d after surgery. Nutritional status, such as rapid turnover protein, postoperative intensive care unit (ICU) length of stay (LOS), postoperative hospital LOS, morbidity, and mortality were investigated prospectively.

RESULTS

There were no significant differences in patient demographic characteristics between the two groups. Levels of retinol-binding protein, as a rapid-turnover protein, were significantly higher on postoperative day (POD) -1, 7, and 14 in the IG compared with the EG group (P = 0.009, P = 0.004, and P = 0.024, respectively). The incidence of postoperative infectious complications and changes to therapeutic antibiotics were significantly lower in the IG group than in the EG group (P = 0.048 and P = 0.012, respectively). There was no significant difference in postoperative ICU or postoperative hospital LOS between the two groups. The 5-y progression-free survival rates in the IG and EG groups were 75% and 64%, respectively (P = 0.188), and the overall survival rates were 68% and 55%, respectively (P = 0.187).

CONCLUSIONS

Perioperative immunonutrition may improve early postoperative nutritional status and reduce postoperative infectious complications in patients with esophageal cancer undergoing esophagectomy.

Overexpression of miR‑221 and miR‑222 in the cancer stroma is associated with malignant potential in colorectal cancer

The cancer stroma is important in cancer development, however, whether the aberrant expression of microRNAs (miRNAs) in the cancer stroma is associated with cancer progression remains to be fully elucidated. The aim of the present study was to identify the miRNAs associated with liver metastasis in the cancer stroma of human colorectal cancer (CRC). Using laser capture microdissection, cancer stroma was obtained from the primary lesion of six patients with CRC with liver metastasis (CRCwLM) and six patients with CRC without liver metastasis (CRCwoLM), and miRNA microarray analysis was performed. Candidate miRNA expression status in the stroma was validated by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) analysis in 40 CRC cases (wLM, n=20; woLM, n=20), and the association between miRNA expression and clinicopathological factors was assessed in 101 advanced CRC samples. The localization of candidate miRNAs in CRCs was analyzed using in situ hybridization analysis (ISH). The microarray analysis identified six miRNAs with expression differing between the CRCwLM and CRCwoLM cancer stroma. Validation using RT‑qPCR analysis of the stroma showed that the expression levels of miR‑221 and miR‑222 in the cancer stroma were significantly higher in CRCwLM than in CRCwoLM. The RT‑qPCR analysis of 101 CRC samples showed that a high expression level of miR‑221 or miR‑222 in the cancer stroma was associated with liver metastasis, distant metastasis, and shorter overall survival rate of patients with CRC (P<0.05). Increased levels of miR‑221 and miR‑222 were observed in cancer cells and in fibroblasts in the stromal tissue in the ISH analysis. The results suggested that the overexpression of miR‑221 and miR‑222 in the cancer stroma is associated with the metastatic activity and malignant potential in patients with CRC.

Abstract 3394: Actionable fusion kinases in microsatellite instability-high colorectal cancers

Colorectal cancer (CRC) patients who are microsatellite instability-high (MSI-H) due to mismatch repair (MMR) deficiency have poor prognosis after relapse by consensus molecular subtyping. In response to reports of some MSI-H CRC resistance to immune checkpoint blockade and immune-related adverse events, we sought to identify a new therapeutic target. MSI testing was done on ~2,800 resected colorectal tumors; next-generation sequencing was done on 149 MSI-H tumors showing MSI in both BAT25 and BAT26 loci. MSI-H CRCs are conventionally divided into hereditary and sporadic categories; in this study whole-exome sequencing, transcriptome sequencing, and methylation array revealed that sporadic MSI-H CRCs are further classifiable into somatic MMR gene mutation (Lynch-like) or MLH1 promoter methylated (MM) types. Methylation of other MMR genes (MSH2/MSH6/PMS2) was not detected. The mutational properties of sporadic MSI-H CRCs harboring somatic MMR gene mutations more closely resembled those of Lynch syndrome-associated MSI-H CRCs than those of MM CRCs, which were more likely to develop in the right-sided colon and harbor more insertions/deletions, more recurrent mutations of BRAF/RNF43, and fewer recurrent mutations of KRAS/APC than Lynch syndrome-associated/Lynch-like CRCs (P &lt; 0.001, Fisher's exact test). Loss of heterozygosity of the locus encompassing TGFBR2, MLH1, and CTNNB1 was specific to Lynch syndrome-associated/Lynch-like MSI-H CRCs; this loss appears to be instrumental in the inactivation of TGFBR2/MLH1. Pathway-level analyses of MSI-H CRCs identified DNA damage-sensing and histone H3 methylation-associated pathways as well as Wnt signaling and RAS/RAF/mitogen-activated protein kinase pathways. One mutational signature, Mutational Signature A, accounted for a median percentage 2.3 times larger of mutations in tumors with mutated PMS2 than in tumors with intact PMS2 (P = 1.5 × 10-5, Mann-Whitney U test). Although it is believed that fusion kinases are found in less than 1% of all CRCs, clinically actionable fusion kinases were detected in 11/19 (58%) MM MSI-H CRCs lacking KRAS/BRAF oncogenes. A 3T3 transformation assay confirmed the tumorigenicity of identified fusion kinases; small-molecule inhibitors that suppress the activity of the kinases identified in fusion products significantly attenuated malignant transformation of 3T3 cells in a concentration-dependent manner. Patients with MSI-H CRCs harboring fusion kinases had worse post-relapse prognoses than did patients with MSI-H CRCs harboring KRAS oncogenes. These findings promise to advance MSI-H CRC precision medicine.

Citation Format: Kazuhito Sato, Masahito Kawazu, Yoko Yamamoto, Toshihide Ueno, Shinya Kojima, Genta Nagae, Manabu Soda, Takafumi Oga, Shinji Kohsaka, Eirin Sai, Yoshihiro Yamashita, Shoichi Hazama, Hisae Iinuma, Hiroyuki Aburatani, Hiroyuki Mano. Actionable fusion kinases in microsatellite instability-high colorectal cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3394.

Current status of immunotherapy against gastrointestinal cancers and its biomarkers: Perspective for precision immunotherapy

Immunotherapy has shown encouraging results for some types of tumor. Although enormous efforts have been made toward the development of specific immunotherapeutic strategies against gastrointestinal cancers, such as adoptive T-cell transfer, peptide vaccines, or dendritic cell vaccines, the efficacy of immunotherapies prior to the introduction of immune checkpoint inhibitors was not substantial. This article reviews immunotherapy for gastrointestinal malignancies, including cell therapy, peptide vaccine, and immune checkpoint inhibitors, and attempts to resolve the immunosuppressive conditions surrounding the tumor microenvironment, and to construct novel combination immunotherapies beyond immune checkpoint inhibitors.

International validation of the consensus Immunoscore for the classification of colon cancer: a prognostic and accuracy study

BACKGROUND

The estimation of risk of recurrence for patients with colon carcinoma must be improved. A robust immune score quantification is needed to introduce immune parameters into cancer classification. The aim of the study was to assess the prognostic value of total tumour-infiltrating T-cell counts and cytotoxic tumour-infiltrating T-cells counts with the consensus Immunoscore assay in patients with stage I-III colon cancer.

METHODS

An international consortium of 14 centres in 13 countries, led by the Society for Immunotherapy of Cancer, assessed the Immunoscore assay in patients with TNM stage I-III colon cancer. Patients were randomly assigned to a training set, an internal validation set, or an external validation set. Paraffin sections of the colon tumour and invasive margin from each patient were processed by immunohistochemistry, and the densities of CD3+ and cytotoxic CD8+ T cells in the tumour and in the invasive margin were quantified by digital pathology. An Immunoscore for each patient was derived from the mean of four density percentiles. The primary endpoint was to evaluate the prognostic value of the Immunoscore for time to recurrence, defined as time from surgery to disease recurrence. Stratified multivariable Cox models were used to assess the associations between Immunoscore and outcomes, adjusting for potential confounders. Harrell's C-statistics was used to assess model performance.

FINDINGS

Tissue samples from 3539 patients were processed, and samples from 2681 patients were included in the analyses after quality controls (700 patients in the training set, 636 patients in the internal validation set, and 1345 patients in the external validation set). The Immunoscore assay showed a high level of reproducibility between observers and centres (r=0·97 for colon tumour; r=0·97 for invasive margin; p<0·0001). In the training set, patients with a high Immunoscore had the lowest risk of recurrence at 5 years (14 [8%] patients with a high Immunoscore vs 65 (19%) patients with an intermediate Immunoscore vs 51 (32%) patients with a low Immunoscore; hazard ratio [HR] for high vs low Immunoscore 0·20, 95% CI 0·10-0·38; p<0·0001). The findings were confirmed in the two validation sets (n=1981). In the stratified Cox multivariable analysis, the Immunoscore association with time to recurrence was independent of patient age, sex, T stage, N stage, microsatellite instability, and existing prognostic factors (p<0·0001). Of 1434 patients with stage II cancer, the difference in risk of recurrence at 5 years was significant (HR for high vs low Immunoscore 0·33, 95% CI 0·21-0·52; p<0·0001), including in Cox multivariable analysis (p<0·0001). Immunoscore had the highest relative contribution to the risk of all clinical parameters, including the American Joint Committee on Cancer and Union for International Cancer Control TNM classification system.

INTERPRETATION

The Immunoscore provides a reliable estimate of the risk of recurrence in patients with colon cancer. These results support the implementation of the consensus Immunoscore as a new component of a TNM-Immune classification of cancer.

FUNDING

French National Institute of Health and Medical Research, the LabEx Immuno-oncology, the Transcan ERAnet Immunoscore European project, Association pour la Recherche contre le Cancer, CARPEM, AP-HP, Institut National du Cancer, Italian Association for Cancer Research, national grants and the Society for Immunotherapy of Cancer.

Hedgehog Signals Mediate Anti-Cancer Drug Resistance in Three-Dimensional Primary Colorectal Cancer Organoid Culture

Colorectal cancer is one of the most common causes of cancer death worldwide. In patients with metastatic colorectal cancer, combination treatment with several anti-cancer drugs is employed and improves overall survival in some patients. Nevertheless, most patients with metastatic disease are not cured owing to the drug resistance. Cancer stem cells are known to regulate resistance to chemotherapy. In the previous study, we established a novel three-dimensional organoid culture model from tumor colorectal tissues of human patients using an air-liquid interface (ALI) method, which contained numerous cancer stem cells and showed resistance to 5-fluorouracil (5-FU) and Irinotecan. Here, we investigate which inhibitor for stem cell-related signal improves the sensitivity for anti-cancer drug treatment in tumor ALI organoids. Treatment with Hedgehog signal inhibitors (AY9944, GANT61) decreases the cell viability of organoids compared with Notch (YO-01027, DAPT) and Wnt (WAV939, Wnt-C59) signal inhibitors. Combination treatment of AY9944 or GANT61 with 5-FU, Irinotecan or Oxaliplatin decreases the cell viability of tumor organoids compared with each anti-cancer drug alone treatment. Treatment with AY9944 or GANT61 inhibits expression of stem cell markers c-Myc, CD44 and Nanog, likely through the decrease of their transcription factor, GLI-1 expression. Combination treatment of AY9944 or GANT61 with 5-FU or Irinotecan also prevents colony formation of colorectal cancer cell lines HCT116 and SW480. These findings suggest that Hedgehog signals mediate anti-cancer drug resistance in colorectal tumor patient-derived ALI organoids and that the inhibitors are useful as a combinational therapeutic strategy against colorectal cancer.

Metastatic ability and the epithelial-mesenchymal transition in induced cancer stem-like hepatoma cells

Cancer stem cells (CSCs) are thought to play important roles in cancer malignancy. Previously, we successfully induced sphere cancer stem-like cells (CSLCs) from several cell lines and observed the property of chemoresistance. In the present study, we examined the metastatic potential of these induced CSLCs. Sphere cancer stem-like cells were induced from a human hepatoma cell line (SK-HEP-1) in a unique medium containing neural survival factor-1. Splenic injection of cells into immune-deficient mice was used to assess hematogenous liver metastasis. Transcriptomic strand-specific RNA-sequencing analysis, quantitative real-time PCR, and flow cytometry were carried out to examine the expression of epithelial-mesenchymal transition (EMT)-related genes. Splenic injection of CSLCs resulted in a significantly increased frequency of liver metastasis compared to parental cancer cells (P < .05). In CSLCs, a mesenchymal marker, Vimentin, and EMT-promoting transcription factors, Snail and Twist1, were upregulated compared to parental cells. Correspondingly, significant enrichment of the molecular signature of the EMT in CSLCs relative to parental cancer cells was shown (q < 0.01) by RNA-sequencing analysis. This analysis also revealed differential expression of CD44 isoforms between CSLCs and parental cancer cells. Increasing CD44 isoforms containing an extra exon were observed, and the standard CD44 isoform decreased in CSLCs compared to parental cells. Interestingly, another CD44 variant isoform encoding a short cytoplasmic tail was also upregulated in CSLCs (11.7-fold). Our induced CSLCs possess an increased liver metastatic potential in which promotion of the EMT and upregulation of CD44 variant isoforms, especially short-tail, were observed.

Fusobacterium nucleatum as a prognostic marker of colorectal cancer in a Japanese population

BACKGROUND

Accumulating evidence shows an overabundance of Fusobacterium nucleatum in colorectal tumor tissues. However, the correlation between the absolute copy number of F. nucleatum in colorectal cancer tissues and colorectal cancer progression is unclear from previous reports. Therefore, we performed a study to compare the abundance of F. nucleatum in colorectal tissues with clinicopathologic and molecular features of colorectal cancer.

METHODS

We collected 100 colorectal cancer tissues and 72 matched normal-appearing mucosal tissues. Absolute copy numbers of F. nucleatum were measured by droplet digital PCR.

RESULTS

The detection rates of F. nucleatum were 63.9% (46/72) in normal-appearing mucosal tissues and 75.0% (75/100) in CRC tissue samples. The median copy number of F. nucleatum was 0.4/ng DNA in the normal-appearing colorectal mucosa in patients with colorectal cancer and 1.9/ng DNA in the colorectal cancer tissues (P = 0.0031). F. nucleatum copy numbers in stage IV colorectal cancer tissues were significantly higher than those in the normal-appearing mucosa in patients with colorectal cancer (P = 0.0016). The abundance of F. nucleatum in colorectal cancer tissues correlated with tumor size and KRAS mutation and was significantly associated with shorter overall survival times; this trend was notable in the patients with stage IV colorectal cancer. Focusing on normal-appearing mucosa in the patients with colorectal cancer, the F. nucleatum copy number was significantly higher in the patients with stage IV rather than stages I-III.

CONCLUSION

These results suggest that determining F. nucleatum levels may help predict clinical outcomes in colorectal cancer patients. Further confirmatory studies using independent datasets are required to confirm our findings.

Cytotoxic T lymphocyte response to peptide vaccination predicts survival in stage III colorectal cancer

We previously reported a phase I clinical trial of a peptide vaccine ring finger protein 43 (RNF43) and 34‐kDa translocase of the outer mitochondrial membrane (TOMM34) combined with uracil‐tegafur (UFT)/LV for patients with metastatic colorectal cancer (CRC), and demonstrated the safety and immunological responsiveness of this combination therapy. In this study, we evaluated vaccination‐induced immune responses to clarify the survival benefit of the combination therapy as adjuvant treatment. We enrolled 44 patients initially in an HLA‐masked fashion. After the disclosure of HLA, 28 patients were in the HLA‐A*2402‐matched and 16 were in the unmatched group. In the HLA‐matched group, 14 patients had positive CTL responses specific for the RNF43 and/or TOMM34 peptides after 2 cycles of treatment and 9 had negative responses; in the HLA‐unmatched group, 10 CTL responses were positive and 2 negative. In the HLA‐matched group, 3‐year relapse‐free survival (RFS) was significantly better in the positive CTL subgroup than in the negative‐response subgroup. Patients with negative vaccination‐induced CTL responses showed a significant trend towards shorter RFS than those with positive responses. Moreover, in the HLA‐unmatched group, the positive CTL response subgroup showed an equally good 3‐year RFS as in the HLA‐matched group. In conclusion, vaccination‐induced CTL response to peptide vaccination could predict survival in the adjuvant setting for stage III CRC.