Combination gemcitabine plus S-1 versus gemcitabine plus cisplatin for advanced/recurrent biliary tract cancer: the FUGA-BT (JCOG1113) randomized phase III clinical trial

BACKGROUND

Gemcitabine plus cisplatin (GC) is the standard treatment of advanced biliary tract cancer (BTC); however, it causes nausea, vomiting, and anorexia, and requires hydration. Gemcitabine plus S-1 (GS) reportedly has equal to, or better, efficacy and an acceptable toxicity profile. We aimed to confirm the non-inferiority of GS to GC for patients with advanced/recurrent BTC in terms of overall survival (OS).

PATIENTS AND METHODS

We undertook a phase III randomized trial in 33 institutions in Japan. Eligibility criteria included chemotherapy-naïve patients with recurrent or unresectable BTC, an Eastern Cooperative Oncology Group Performance Status of 0 - 1, and adequate organ function. The calculated sample size was 350 with a one-sided α of 5%, a power of 80%, and non-inferiority margin hazard ratio (HR) of 1.155. The primary end point was OS, while the secondary end points included progression-free survival (PFS), response rate (RR), adverse events (AEs), and clinically significant AEs defined as grade ≥2 fatigue, anorexia, nausea, vomiting, oral mucositis, or diarrhea.

RESULTS

Between May 2013 and March 2016, 354 patients were enrolled. GS was found to be non-inferior to GC [median OS: 13.4 months with GC and 15.1 months with GS, HR, 0.945; 90% confidence interval (CI), 0.78-1.15; P = 0.046 for non-inferiority]. The median PFS was 5.8 months with GC and 6.8 months with GS (HR 0.86; 95% CI 0.70-1.07). The RR was 32.4% with GC and 29.8% with GS. Both treatments were generally well-tolerated. Clinically significant AEs were observed in 35.1% of patients in the GC arm and 29.9% in the GS arm.

CONCLUSIONS

GS, which does not require hydration, should be considered a new, convenient standard of care option for patients with advanced/recurrent BTC.

CLINICAL TRIAL NUMBER

This trial has been registered with the UMIN Clinical Trials Registry (http://www.umin.ac.jp/ctr/index.htm), number UMIN000010667.

Comprehensive Comparative Analysis of Prognostic Value of Systemic Inflammatory Biomarkers for Patients with Stage II/III Colon Cancer

BACKGROUND

Among numerous systemic inflammatory biomarkers, it remains unclear which is the most prognostic for patients with stage II/III colon cancer. We aimed to compare the prognostic significance of systemic inflammatory biomarkers among patients with stage II/III colon cancer.

METHODS

We included 1303 patients with stage II/III colon cancer who underwent potentially curative resection from July 2004 to December 2013. Sixteen systemic inflammatory biomarkers-derived from combinations of neutrophils, lymphocytes, monocytes, platelets, C-reactive protein (CRP), and albumin-were compared to identify the biomarker most associated with overall survival (OS) and disease-free survival (DFS) using receiver operating characteristic (ROC) curve analysis.

RESULTS

Nine inflammatory biomarkers were predictive for OS, among which lymphocyte-to-CRP ratio (LCR), CRP-to-albumin ratio (CAR), neutrophil × CRP, monocyte × CRP, and platelet × CRP were also predictive for DFS. Among these five inflammatory biomarkers, the area under the curve (AUC) value was highest (0.630) for LCR, being significantly higher than that for neutrophil × CRP (P = 0.010), monocyte × CRP (P = 0.007), or platelet × CRP (P = 0.010) for OS. When the prognostic impact of LCR and CAR were analyzed by multivariate analysis, only LCR was an independent predictor of both OS [hazard ratio (HR), 1.77; 95% confidence interval (CI), 1.23-2.60; P = 0.002] and DFS (HR, 1.29; 95% CI, 1.00-1.66; P = 0.048).

CONCLUSIONS

LCR may be the most useful predictive factor for OS and DFS in patients with stage II or III colon cancer.

P3389Angioscopic differences in quality and quantity of neointima in patients experiencing an acute coronary syndrome treated with bare metal, first-, second-, and third generation drug-eluting stents

Background

Although drug-eluting stents (DES) have substantially reduced the need for early target lesion revascularization (TLR) compared with bare-metal stents (BMS) by inhibiting neointima hyperplasia, early generation DES have been associated with an increased risk of very late stent failure (VLSF) due to stent thrombosis and TLR after 1 year. Although the incidence of VLSF is reduced with newer generation DES, VLSF remains an unresolved problem and its mechanisms are not fully explored.

Purpose

The purpose of this study was to evaluate quality and quantity of neointima and presence of thrombus by using coronary angioscopy at long-term follow-up in patients who experienced an acute coronary syndrome (ACS) treated with BMS and DES on dual antiplatelet therapy.

Methods

Coronary angioscopy was performed at 6 and 10 months after BMS and DES implantation, respectively, in ACS patients. We assessed neointimal coverage (NC) of the stent struts, yellow color grade (YG) of stented segment and the existence of thrombus. Angioscopic NC was defined as follows: grade 0= fully visible struts; grade 1= visible struts through thin neointima; grade 2= no visible struts. We determined maximum (Max-NC) and minimum coverage (Min-NC) grades and the dominant NC grades. YG was classified into 4 grades (0= white; 1= slight yellow; 2= yellow; 3= intensive yellow). The obtained findings were compared with BMS, first-generation (1st-) DES, second-generation (2nd-) DES and third-generation (3rd-) DES.

Results

A total of 212 patients were enrolled: BMS (n=127), 1st DES (n=26, sirolimus-eluting stent), 2nd-DES (n=38, permanent polymer everolimus-eluting stent), and 3rd-DES (n=21, bioresorbable polymer everolimus-eluting stent). Max-NC and Min-NC grade were significantly lower with 1st- and 2nd-DES than with BMS and 3rd-DES (Figure). The same trend was also observed in the dominant NC grades. There was a lower trend of YG in BMS and 3rd-DES than in 1st or 2nd-DES (Figure). The presence of thrombus was significantly lower in 3rd-DES in comparison with BMS, 1st-, and 2nd-DES (3rd-DES 0%, BMS 20.5%, 1st-DES 24%, 2nd-DES 13.5%, P=0.01).

Figure 1

Conclusion

Patients treated with 3rd-DES have higher NC grade, lower incidence of intrastent thrombus, and lower YG than in 1st and 2nd-DES. These findings may explain the lower incidence of VLSF associated with these newer generation stent platforms.

P5601High pulse wave velocity is associated with poor shrinkage of abdominal aortic aneurysm in endovascular aneurysm repair patients

Background

Endovascular aneurysm repair (EVAR) has widely spread for treatment of abdominal aortic aneurysm (AAA). However, the effects of EVAR on vascular function remain to be clarified. According to several reports, changes in aortic stiffness after EVAR reflect badly on future cardiovascular events. Recently, brachial-ankle pulse wave velocity (baPWV) is accepted as the most simple and reproducible method to determine the aortic stiffness.

Purpose

We aimed to evaluate the change of baPWV following EVAR and investigate the relationship between the aortic stiffness and the long-term outcomes following EVAR.

Methods

We enrolled 172 patients who underwent primary EVAR between January 2009 and December 2017 in our University hospital. Patients with saccular aneurysm, iliac aneurysm and pseudo aneurysm were excluded from the analysis. PWV data were collected before and 1 week after EVAR. PWV was measured as the mean baPWV values of both lower limbs. The long-term outcomes were evaluated with the cardiovascular event and AAA changing rate (mm/year) which was calculated by computed tomographic scanning at the preoperative and latest imaging studies. The cardiovascular event was defined as the expansion of thoracic or abdominal aortic aneurysm (>10 mm or >5 mm/year), central nervous system disorder, acute heart failure, new arrhythmia, peripheral arterial disease. Receiver operating characteristic (ROC) curve analysis was used to evaluate the cut off values of preoperative baPWV (pre-PWV) and postoperative baPWV (post-PWV) for the risk factor of cardiovascular event.

Results

The mean age was 76.6±7.5 years and 149 patients (86.7%) were male. The mean follow-up period was 41.6±27.0 months. The mean AAA changing rate was −1.84±4.72 mm/year. Post-PWV was significantly increased compared to pre-PWV (pre-PWV v.s. post-PWV; 1885±382 cm/s vs. 2060±528 cm/s, p<0.0001). The optimal cut-off values of the pre and post PWV for predicting cardiovascular events were 1900 cm/s and 2100 cm/s, respectively. The Kaplan-Meier curves indicate that 5 year-cardiovascular event free rates were 45.9% in the patients with pre PWV ≥1900 cm/s and 73.2% in the patients with pre PWV <1900 cm/s (p=0.0185). Similarly, 5 year-cardiovascular event free rates were 46.6% in the patients with post-PWV ≥2100cm/s and 73.4% in the patients with post PWV <2100 cm/s (p=0.0162). Furthermore, the linear regression analysis indicated that post-PWV values correlated positively with the AAA changing rate (r=0.1811, p=0.0195) while pre-PWV was not associated with AAA changing rate (r=0.1211, p=0.1201).

Conclusions

Our results show that EVAR increase aortic stiffness in the acute phases and high post-baPWV is associated with poor shrinkage of abdominal aortic aneurysm in EVAR patients. This is the first study to demonstrate the association between high PWV and poor long-term outcome in endovascular aneurysm repair patients.

Visualization and quantification of anastomotic perfusion in colorectal surgery using near-infrared fluorescence

BACKGROUND

Anastomotic leakage (AL) is one of the most troublesome complications in colorectal surgery. Recently, near-infrared fluorescence (NIRF) imaging has been used intraoperatively to detect sentinel lymph nodes and visualize the blood supply at the region of interest (ROI). The aim of this study was to evaluate the role of visualization and quantification of bowel perfusion around the anastomosis using NIRF system in predicting AL.

METHODS

A prospective study was conducted on patients who had laparoscopic surgery for colorectal cancer at our institution. Perfusion of the anastomosis was evaluated with NIRF imaging after intravenous injection of indocyanine green (ICG). The time course of fluorescence intensity was recorded by an imaging analyzer We measured the time from ICG injection to the beginning of fluorescence (T₀), maximum intensity (I_max), time to reach I_max (T_max), time to reach I_max 50% ([Formula: see text]) and slope (S) after the anastomosis.

RESULTS

Tumor locations were as follows; cecum: 2, ascending colon: 2, transverse colon: 7, descending colon: 1, sigmoid colon: 2, rectosigmoid colon: 3 and rectum: 6 (one case with synchronous cancer). All operations were performed laparoscopically. Four patients were diagnosed with or suspected to have AL (2 patients with grade B anastomotic leakage after low anterior resection, 1 patient with minor leakage in transverse colon resection and 1 patient needing re-anastomosis intraoperatively in transverse colon resection). T₀ was significantly longer in the AL group than in patients without AL (64.3 ± 27.6 and 18.2 ± 6.6 s, p = 2.2 × 10^-3).

CONCLUSIONS

Perfusion of the anastomosis could be successfully visualized and quantified using NIRF imaging with ICG. T₀ might be a useful parameter for prediction of AL.

The Short- and Long-Term Feasibility of Laparoscopic Surgery in Colon Cancer Patients with Bulky Tumors

BACKGROUND

Compared to open surgery for colon cancer, randomized controlled trials have shown that laparoscopic approaches have equivalent short- and long-term outcomes. However, the feasibility of laparoscopy for removal of bulky tumors has not been evaluated. The aim of our study was to determine the short- and long-term feasibility of laparoscopic surgery for bulky (> 8 cm) colon cancer.

METHODS

A total of 80 patients with bulky tumors (defined as greater than 8 cm in diameter) underwent curative resection from July 2004 to July 2014. Short- and long-term outcomes were compared between patients undergoing laparoscopic (n = 48) and open (n = 32) resection.

RESULTS

Compared to open, the operative time was significantly longer (213 vs. 148 min, p < 0.001), return of bowel function quicker (time to oral intake; 2 vs. 5 days, p < 0.001), and length of stay shorter (10 vs. 13 days, p < 0.001) in the laparoscopic group. Five-year cancer-specific and relapse-free survival was similar with no patients developing local recurrence in either group.

CONCLUSIONS

Laparoscopic resection of colon cancers greater than 8 cm in diameter is feasible and oncologically safe with better short-term and equivalent long-term outcomes compared to open surgery.

Prediction of early colorectal cancer metastasis by machine learning using digital slide images

BACKGROUND AND OBJECTIVES

Prediction of lymph node metastasis (LNM) for early colorectal cancer (CRC) is critical for determining treatment strategies after endoscopic resection. Some histologic parameters for predicting LNM have been established, but evaluator error and inter-observer disagreement are unsolved issues. Here we describe an LNM prediction algorithm for submucosal invasive (T1) CRC based on machine learning.

METHODS

We conducted a retrospective single-institution study of 397 T1 CRCs. Several morphologic parameters were extracted from whole slide images of cytokeratin immunohistochemistry using Image J. A random forest algorithm for a training dataset (n = 277) was executed and used to predict LNM for the test dataset (n = 120). The results were compared with conventional histologic evaluation of hematoxylin-eosin staining.

RESULTS

Machine learning showed better LNM predictive ability than the conventional method on some datasets. Cross validation revealed no significant difference between the methods. Machine learning resulted in fewer false-negative cases than the conventional method.

CONCLUSIONS

Machine learning on whole slide images is a potential alternative for determining treatment strategies for T1 CRC.

Prognostic impact of residual lateral lymph node metastasis after neoadjuvant (chemo)radiotherapy in patients with advanced low rectal cancer

Background

There is a lack of large studies focusing on the prognostic significance of lateral lymph node (LLN) metastasis following LLN dissection (LLND) in rectal cancer. The aim of this study was to evaluate the prognostic impact of LLN metastases on survival of patients with advanced low rectal cancer.

Methods

Consecutive patients with locally advanced, but not metastatic, extraperitoneal rectal cancer treated with neoadjuvant (chemo)radiotherapy plus total mesorectal excision between 2004 and 2015 were included in the study. LLND was performed when pretreatment imaging documented enlarged LLNs (7 mm or greater in size). Localization of nodal metastases and long‐term outcomes were analysed. Kaplan–Meier analysis was used to compare the survival of patients with ypN0 disease with that of patients with mesorectal ypN+/LLN− status and patients with positive LLNs. The Cox proportional hazards model was used to evaluate predictors of disease‐free survival (DFS) and local recurrence.

Results

A total of 613 patients were included in the study; LLND was performed in 212 patients (34·6 per cent) and 57 (9·3 per cent) had LLN metastasis. Patients with LLN metastasis had improved DFS and local recurrence cumulative incidence rates compared with patients with mesorectal ypN2+/LLN− disease (DFS: P = 0·014; local recurrence: P = 0·006). Although the DFS rate of patients with LLN metastasis was worse than that of patients with ypN0 disease (P < 0·001), the cumulative incidence of local recurrence was similar (P = 0·491). In multivariable analysis, residual LLN metastasis was not an independent predictor of worse DFS or local recurrence.

Conclusion

LLN metastasis is not an independent predictor of local recurrence or survival. Survival of patients presenting with LLN metastasis after (chemo)radiotherapy was intermediate between that of patients with ypN0 status and those with mesorectal ypN2 positivity.

Simultaneous laparoscopic left hemicolectomy and spleen-preserving distal pancreatectomy for descending colon cancer with pancreatic invasion

Here, we describe laparoscopic colectomy with spleen-preserving distal pancreatectomy for descending colon cancer with pancreatic tail invasion. A 69-year-old man with descending colon cancer staged as clinical state IIIC (cT4b [pancreas] N1M0) underwent definitive laparoscopic surgery that was performed in collaboration with surgeons who specialize in laparoscopic colorectal and hepatobiliary-pancreatic laparoscopy. After the left colon was mobilized, tumor infiltration of the pancreas, but not the splenic vessels, was confirmed, and the spleen was preserved. The procedures were safely completed laparoscopically, without intraoperative and postoperative complications. Laparoscopic multivisceral resection could be a treatment option for similar patients but only when performed by multidisciplinary specialists.

Immunogenomic profiles associated with response to neoadjuvant chemoradiotherapy in patients with rectal cancer

BACKGROUND

Accumulating evidence suggests that radiotherapy success has an immune-associated component. The immunogenomic profiles associated with responses to chemoradiotherapy (CRT) were assessed in patients with locally advanced rectal cancer in this study.

METHODS

CD8+ tumour-infiltrating lymphocyte (TIL) and stromal lymphocyte densities were assessed by immunohistochemistry using pretreatment biopsies from patients with advanced rectal cancer who had preoperative CRT. Whole-exome sequencing and gene expression microarray analysis were conducted to investigate the genomic properties associated with the response to CRT and CD8+ TIL density. Response to CRT was determined based on Dworak tumour regression grade (TRG); tumours with complete (TRG 4) or near-complete (TRG 3) regression were grouped as good responders, and those with TRG 1 as non-responders.

RESULTS

Immunohistochemical examinations (275 patients) showed that pre-CRT CD8+ TIL density was associated with better response to CRT and improved recurrence-free survival, whereas pre-CRT stromal CD8+ cell density was not associated with either response to CRT or recurrence-free survival. Whole-exome sequencing (74 patients) showed that the numbers of single-nucleotide variations (SNVs) and neoantigens predicted from SNVs were higher in good responders than in non-responders, and these correlated positively with CD8+ TIL density (r_S  = 0·315 and r_S  = 0·334 respectively). Gene expression microarray (90 patients) showed that CD8A expression correlated positively with the expression of programmed cell death 1 (PDCD1) (r_S  = 0·264) and lymphocyte-activation gene 3 (LAG3) (r_S  = 0·507).

CONCLUSION

Pre-CRT neoantigen-specific CD8+ T cell priming may be a key event in CRT responses where immune checkpoint molecules could be useful targets to enhance tumour regression.

Feasibility of needlescopic surgery for colorectal cancer: safety and learning curve for Japanese Endoscopic Surgical Skill Qualification System-unqualified young surgeons

BACKGROUND

Needlescopic surgery (NS) is a minimally invasive technique for colorectal cancer. NS may be easier to perform than other minimally invasive surgery such as single-incision laparoscopic surgery and natural orifice transluminal endoscopic surgery because the port setting is the same while the shafts are thinner than in conventional laparoscopic surgery. We evaluated the capability of introducing this surgery for sigmoid and rectosigmoid colon cancer by assessing the learning curve in Japanese Endoscopic Surgical Skill Qualification System (JESSQS)-unqualified surgeons.

METHODS

In this retrospective study, 112 cases of sigmoidectomy and anterior resection were performed by NS from October 2011 to December 2015 in our institution. Surgical outcomes including operation time, blood loss, postoperative hospital stay, perioperative complications, and overall survival were compared between JESSQS-qualified surgeons (Group A) and JESSQS-unqualified surgeons (Group B). The learning curve for NS was established using the average operation times in JESSQS-unqualified surgeons.

RESULTS

Groups A and B comprised of 41 and 71 patients, respectively. Ninety patients underwent sigmoidectomy and 22 patients underwent anterior resection. No conversion to open surgery occurred. The operation time was significantly shorter in Group A than B (P = 0.0080). There were no significant differences in blood loss, the postoperative hospital stay, perioperative complications, or overall survival between the two groups. These variables were similar even when NS was considered relatively difficult, as in patients with obesity (body mass index of ≥ 25 kg/m²), bulky tumors (tumor size of ≥ 50 mm), and stage III/IV cancer. The average operation time in JESSQS-unqualified young surgeons was significantly shorter in the ninth and tenth cases than in the first and second cases of NS (P = 0.0282).

CONCLUSIONS

NS for sigmoid and rectosigmoid colon cancer was performed safely by both JESSQS-qualified surgeons and JESSQS-unqualified surgeons. Even JESSQS-unqualified young surgeons might be able to quickly learn NS techniques.

Randomized controlled trial on efficacy of oligomeric formula (HINE E-GEL®) versus polymeric formula (MEIN®) enteral nutrition after esophagectomy for esophageal cancer with gastric tube reconstruction

The efficacy of early enteral nutrition after esophageal cancer surgery has been reported. However, the choice of formula and management of diarrhea are important to achieve the goal of enhanced recovery after surgery. The aim of this study is to assess the frequency of diarrhea/completion rate of enteral nutrition regimen as primary endpoints and the postoperative nutritional status/body composition analysis/operative morbidity as secondary endpoints was compared between the two nutrition groups. Among the 122 patients who underwent esophagectomy for esophageal cancer between December 2015 and September 2017, 67 patients who met the eligibility criteria were randomly assigned to receive enteral nutrition with either HINE E-GEL® (HINE group; n = 33) or MEIN® (MEIN group; n = 34). The incidence of diarrhea was significantly lower in the HINE group (18.2 % vs. 64.7 %, P < 0.001). The score of Bristol scale of POD 6/7 was significantly lower in the HINE group (P = 0.019/P = 0.006, respectively). The completion rate of enteral nutrition regimen was significantly higher in the HINE group (97.4 % vs. 86.6 %, P = 0.002). The Controlling Nutritional Status scores and total protein levels at 6 months after surgery were significantly better in the HINE group (P = 0.030 and P = 0.023, respectively), indicating improved tendency in nutritional status in the HINE group. However, there were no significant differences in Prognostic Nutritional Index values, blood test results, rapid turnover proteins, body mass index, or body composition between the two groups. HINE E-GEL compared with MEIN may reduce the frequency of diarrhea, enabling patients to adhere to the scheduled enteral nutrition plan. Also, maintenance of nutritional status with HINE E-GEL was comparable or potentially better in some nutrition components to that with MEIN, indicating that HINE E-GEL can be an option for enteral nutrition following esophageal surgery to achieve the goal of successful completion of scheduled enteral nutrition and smooth transition to the normal diet.

Phase II Trial of Neoadjuvant Chemotherapy, Chemoradiotherapy, and Laparoscopic Surgery with Selective Lateral Node Dissection for Poor-Risk Low Rectal Cancer

PURPOSE

The aim of this study is to evaluate the safety and efficacy of induction modified 5-fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6) plus bevacizumab followed by S- 1-based chemoradiotherapy in magnetic resonance imaging (MRI)-defined poor-risk locally advanced low rectal cancer.

PATIENTS AND METHODS

This was a prospective phase II trial at a single comprehensive cancer center. The primary endpoint was the pathological complete response (pCR) rate. Eligible patients had clinical stage II-III low rectal adenocarcinoma with any of the following MRI-defined poor-risk features: circumferential resection margin (CRM) ≤ 1 mm, cT4, positive lateral nodes, mesorectal N2 disease, and/or requiring abdominoperineal resection. Patients received six cycles of mFOLFOX6 with 5 mg/kg bevacizumab followed by oral S-1 (80 mg/m²/day on days 1-14 and 22-35) plus radiotherapy (50.4 Gy). Surgery was conducted through a laparoscopic approach. Lateral node dissection was selectively added when the patient had enlarged lateral nodes.

RESULTS

A total of 43 patients were enrolled. Grade 3-4 adverse events occurred in nine patients during induction chemotherapy and in five patients during chemoradiotherapy. One patient declined surgery with a clinical complete response. Forty-two patients underwent surgery, and 16 had pCR [37.2%, 95% confidence interval (CI) 24.4-52.1%]. All underwent R0 resection without conversion, including combined resection of adjacent structures (n = 14) and lateral node dissection (n = 30). Clavien-Dindo grade 3-4 complications occurred in six patients (14.3%). With median follow-up of 52 months, six developed recurrences (lung n = 5, local n = 1; 3-year relapse-free survival 86.0%).

CONCLUSIONS

This study achieved a high pCR rate with favorable toxicity and postoperative complications in poor-risk locally advanced low rectal cancer. Multicenter study is warranted to evaluate this regimen.

Feasibility of neoadjuvant therapy for elderly patients with locally advanced rectal cancer

PURPOSE

The feasibility of neoadjuvant therapy (NAT) for elderly patients with rectal cancer has not been evaluated well.

METHODS

Between 2004 and 2014, 506 patients with locally advanced low rectal cancer underwent curative resection. Fifty-four were over 75 years old (elderly group), and 452 were under 75 years old (young group). The patients were divided into sub-groups according to whether they received NAT.

RESULTS

Nineteen (35.2%) patients from the elderly group and 348 (77.0%) from the young group received NAT. The proportion of patients who received NAT was significantly lower in the elderly group. In the elderly group, the median age and prevalence of co-morbidities were significantly lower in patients with than in those without NAT. The incidence of severe adverse events was similar in the two groups. On multivariate analysis, age was not related to postoperative complications in patients who received NAT. The 5-year local recurrence rate was significantly lower in the elderly patients who received NAT, and similar to that of the young patients who received NAT.

CONCLUSIONS

Neoadjuvant therapy was feasible and should be considered as a treatment option for carefully selected elderly patients with locally advanced low rectal cancer.

IFN/STAT signaling controls tumorigenesis and the drug response in colorectal cancer

Colorectal cancer (CRC) is caused by genetic alterations, and comprehensive sequence analyses have revealed the mutation landscapes. In addition to somatic changes, genetic variations are considered important factors contributing to tumor development; however, our knowledge on this subject is limited. Familial adenomatous polyposis coli (FAP) is an autosomal‐dominant inherited disease caused by germline mutations in the adenomatous polyposis coli (APC) gene. FAP patients are classified into two major groups based on clinical manifestations: classical FAP (CFAP) and attenuated FAP (AFAP). In this study, we established 42 organoids from three CFAP patients and two AFAP patients. Comprehensive gene expression analysis demonstrated a close association between IFN/STAT signaling and the phenotypic features of FAP patients. Genetic disruption of Stat1 in the mouse model of FAP reduced tumor formation, demonstrating that the IFN/STAT pathway is causally associated with the tumor‐forming potential of APC‐deficient tumors. Mechanistically, STAT1 is downstream target of KRAS and is phosphorylated by its activating mutations. We found that enhanced IFN/STAT signaling in CFAP conferred resistance to MEK inhibitors. These findings reveal the crosstalk between RAS signaling and IFN/STAT signaling, which contributes to the tumor‐forming potential and drug response. These results offer a rationale for targeting of IFN/STAT signaling and for the stratification of CRC patients.