Alfredo Mellano

Stromal contribution to the colorectal cancer transcriptome

Recent studies identified a poor-prognosis stem/serrated/mesenchymal (SSM) transcriptional subtype of colorectal cancer (CRC). We noted that genes upregulated in this subtype are also prominently expressed by stromal cells, suggesting that SSM transcripts could derive from stromal rather than epithelial cancer cells. To test this hypothesis, we analyzed CRC expression data from patient-derived xenografts, where mouse stroma supports human cancer cells. Species-specific expression analysis showed that the mRNA levels of SSM genes were mostly due to stromal expression. Transcriptional signatures built to specifically report the abundance of cancer-associated fibroblasts (CAFs), leukocytes or endothelial cells all had significantly higher expression in human CRC samples of the SSM subtype. High expression of the CAF signature was associated with poor prognosis in untreated CRC, and joint high expression of the stromal signatures predicted resistance to radiotherapy in rectal cancer. These data show that the distinctive transcriptional and clinical features of the SSM subtype can be ascribed to its particularly abundant stromal component.

The genomic landscape of response to EGFR blockade in colorectal cancer

Colorectal cancer is the third most common cancer worldwide, with 1.2 million patients diagnosed annually. In late-stage colorectal cancer, the most commonly used targeted therapies are the monoclonal antibodies cetuximab and panitumumab, which prevent epidermal growth factor receptor (EGFR) activation. Recent studies have identified alterations in KRAS and other genes as likely mechanisms of primary and secondary resistance to anti-EGFR antibody therapy. Despite these efforts, additional mechanisms of resistance to EGFR blockade are thought to be present in colorectal cancer and little is known about determinants of sensitivity to this therapy. To examine the effect of somatic genetic changes in colorectal cancer on response to anti-EGFR antibody therapy, here we perform complete exome sequence and copy number analyses of 129 patient-derived tumour grafts and targeted genomic analyses of 55 patient tumours, all of which were KRAS wild-type. We analysed the response of tumours to anti-EGFR antibody blockade in tumour graft models and in clinical settings and functionally linked therapeutic responses to mutational data. In addition to previously identified genes, we detected mutations in ERBB2, EGFR, FGFR1, PDGFRA, and MAP2K1 as potential mechanisms of primary resistance to this therapy. Novel alterations in the ectodomain of EGFR were identified in patients with acquired resistance to EGFR blockade. Amplifications and sequence changes in the tyrosine kinase receptor adaptor gene IRS2 were identified in tumours with increased sensitivity to anti-EGFR therapy. Therapeutic resistance to EGFR blockade could be overcome in tumour graft models through combinatorial therapies targeting actionable genes. These analyses provide a systematic approach to evaluating response to targeted therapies in human cancer, highlight new mechanisms of responsiveness to anti-EGFR therapies, and delineate new avenues for intervention in managing colorectal cancer.

Transanal total mesorectal excision (taTME) for cancer located in the lower rectum: Short- and mid-term results

BACKGROUND Laparoscopic trans-abdominal total mesorectal excision is technically demanding. Transanal Total Mesorectal Excision (taTME) is a new technique which seems to provide technical advantages. This study describes the results of taTME in a consecutive series of patients with low rectal cancer. METHODS From January 2012 to December 2013, a consecutive series of 26 patients with low rectal cancer underwent laparoscopic taTME with coloanal anastomosis. cT4 or Type II-III rectal cancer (according to Rulliers classification) were contraindications to taTME. After anal sleeve mucosectomy, the rectal wall was transected at the ano-rectal junction. A single-access multichannel port was inserted in the anal canal. taTME was performed from down to up until the sacral promontory posteriorly and the Pouch of Douglas anteriorly were reached. A laparoscopic trans-abdominal approach was used to complete the left colon mobilization. RESULTS Sixteen patients (61.5%) were male. The mean distance of the rectal cancer from the anal verge was 4.4 cm (range 3-6). Nineteen patients (73.1%) received long-course neoadjuvant radiotherapy. At final pathology, resection margins were negative in all the patients: the mean distal and radial resection margins were 19 mm and 11.2 mm, respectively. TME was complete in 23 patients (88.5%) and nearly complete in three. Postoperative mortality was 3.8%. The overall morbidity rate was 26.9% (7 patients): two patients (7.7%) had an anastomotic leakage (Dindo I-d). After a mean follow up of 23 months, no patients have developed a local recurrence. CONCLUSIONS laparoscopic taTME allow wide resection margins and good quality TME.

MACC1 mRNA levels predict cancer recurrence after resection of colorectal cancer liver metastases.

Objective:Upon colon cancer metastasis resection in liver, disease outcome is heterogeneous, ranging from indolent to very aggressive, with early recurrence. The aim of this study is to investigate the capability of metastasis associated in colon cancer 1 (MACC1) levels measured in liver metastasis specimens to predict further recurrence of the disease. Methods:Gene expression and gene dosage of MACC1, hepatocyte growth factor (HGF), and hepatocyte growth factor receptor (MET) were assessed using quantitative realtime polymerase chain reaction on a cohort of 64 liver metastasis samples from patients with complete follow-up of 36 months and detailed clinical annotation. The most relevant mutations associated to prognosis in colorectal cancer, KRAS, and PIK3CA were assessed on the same specimens with Sanger sequencing. Results:Receiver operating characteristic (ROC) analysis revealed that MACC1 mRNA abundance is a good indicator of metastatic recurrence (AUC = 0.65, P < 0.05), whereas no such results were obtained with MET and HGF, nor with gene dosage. Generation of MACC1-based risk classes was capable of successfully separating patients into poor and good prognosis subgroups [hazard ratio (HR) = 5.236, 95% confidence interval (CI) = 1.2068–22.715, P < 0.05]. Also KRAS mutation was significantly associated with higher risk of recurrence (HR = 2.07, 95% CI = 1.048–4.09, P < 0.05). Cox regression multivariate analysis supported the independence of MACC1, but not KRAS, from known prognostic clinical information (Node Size HR = 3.155, 95% CI = 1.4418–6.905, P < 0.001, Preoperative carcinoembryonic antigen HR = 2.359, 95% CI = 1.0203–5.452, P < 0.05, MACC1 HR = 7.2739, 95% CI = 1.6584–31.905, P < 0.01). Conclusions:MACC1, a new easily detectable biomarker in cancer, is an independent prognostic factor of recurrence after liver resection of colorectal cancer metastasis.

Iterative procedures combining cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for isolated peritoneal recurrence

Abstract Purpose: The aim of this study was to analyse feasibility, morbidity and outcome of repeat complete cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC). CRS combined with HIPEC is becoming the gold standard treatment for resectable peritoneal carcinomatosis in highly selected patients. As yet treatment of isolated peritoneal recurrence with iterative CRS and HIPEC has not been thoroughly explored. Materials and methods: We selected 16 patients presenting isolated peritoneal recurrence who had undergone iterative CRS and HIPEC from a dataset of 322 CRS associated with HIPEC performed between 1996 and 2012. Results: Peritoneal carcinomatosis (PC) was due to colorectal and ovarian cancer, peritoneal mesothelioma and pseudomyxoma peritonei (PMP). Disease-free survival (DFS) was 13 months after the first procedure and 13.7 months after the second one. Overall morbidity rate was 43.7% (7/16) for all patients, with grade III–IV complications in three patients (18.7%). Conclusions: Iterative procedures combining cytoreductive surgery and HIPEC are feasible with acceptable morbidity and mortality rates in strictly selected patients. DFS following repeated CRS and HIPEC is comparable to that registered after the first procedure.

Pulmonary Complications after Surgery for Rectal Cancer in Elderly Patients: Evaluation of Laparoscopic versus Open Approach from a Multicenter Study on 477 Consecutive Cases

Aim To evaluate the impact of open or laparoscopic rectal surgery on pulmonary complications in elderly (>75 years old) patients. Methods Data from consecutive patients who underwent elective laparoscopic or open rectal surgery for cancer were collected prospectively from 3 institutions. Pulmonary complications were defined according to the ACS/NSQUIP definition. Results A total of 477 patients (laparoscopic group: 242, open group: 235) were included in the analysis. Postoperative pulmonary complications were significantly more common after open surgery (8 out of 242 patients (3.3%) versus 23 out of 235 patients (9.8%); p = 0.005). In addition, PPC occurrence was associated with the increasing of postoperative pain (5.04 ± 1.62 versus 5.03 ± 1.58; p = 0.001) and the increasing of operative time (270.06 ± 51.49 versus 237.37 ± 65.97; p = 0.001). Conclusion Our results are encouraging to consider laparoscopic surgery a safety and effective way to treat rectal cancer in elderly patients, highlighting that laparoscopic surgery reduces the occurrence of postoperative pulmonary complications.

Intracorporeal versus extracorporeal anastomosis after laparoscopic left colectomy for splenic flexure cancer: results from a multi-institutional audit on 181 consecutive patients

Although intracorporeal anastomosis has been demonstrated to be safe and effective after right colectomy, limited data are available about its efficacy after left colectomy for colon cancer located in splenic flexure. A multi-institutional audit was designed, including 92 patients who underwent laparoscopic left colectomy with intracorporeal anastomosis (IA) compared with 89 matched patients who underwent a laparoscopic left colectomy with extracorporeal anastomosis (EA). There was no significant difference in terms of age, sex, BMI, and ASA score between the two groups. Post-surgical history and stage of disease according to AJCC/UICC TNM were also similar. IA and EA groups demonstrated similar oncologic radicality in terms of the number of lymph nodes harvested (18.5 ± 9 vs. 17.5 ± 8.4; p = 0.48). Recovery after surgery was also better in patients who underwent IA, as confirmed by the shorter time to flatus in the IA group (2.6 ± 1.1 days vs. 3.4 ± 1.2 days; p < 0.001) and higher post-operative pain expressed in the mean VAS Scale in the EA group (1.7 ± 2.1 vs. 3.5 ± 1.6; p < 0.001). Laparoscopic left colectomy with intracorporeal anastomosis was associated with a lower rate of post-operative complications (OR 6.7, 95% CI 2.2–20; p = 0.001). However, when stratifying according to Clavien classification, the difference was consistently confirmed for less severe (class I and II) complications (OR 7.6, 95% CI 2.5–23, p = 0.001) but not for class III, IV, and V complications (OR 1.8, 95% CI 0.1–16.9; p = 0.59). Our results were consistent to hypothesize that a complete laparoscopic approach could be considered a safe method to perform laparoscopic left colectomy with the advantage of a guaranteed faster recovery after surgery. Further randomized clinical trials are needed to obtain a more definitive conclusion.

Corrigendum: Stromal contribution to the colorectal cancer transcriptome

Nat. Genet. 47, 312–319 (2015); published online 23 February 2015; corrected after print 29 August 2016 In the version of this article initially published, an affiliation for author Zsolt Fekete was incorrectly omitted. The missing affiliation was to the Department of Oncology, University of Medicine and Pharmacy Iuliu Hatieganu, Cluj-Napoca, Romania.

Abstract 4760: Stromal contribution to the colorectal cancer transcriptome

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Recent studies have identified a stem/serrated/mesenchymal (SSM) molecular subtype of colorectal cancer (CRC) that is associated with poor prognosis. We noted that genes upregulated in this subtype are also prominently expressed by stromal cells. This led us to hypothesize that the SSM transcripts could derive from the tumor microenvironment, rather than being intrinsic to cancer cells. To test this hypothesis, we analyzed microarray and RNAseq expression data from patient-derived xenografts (PDXs) of CRC, where human cancer cells are supported by murine stroma. Species-specific expression analysis revealed that mRNA levels of SSM genes are mostly due to stromal expression. Considering only genes exclusively expressed by stromal cells in PDXs, We then built three expression signatures specifically reporting the abundance of cancer-associated fibroblasts (CAFs), leucocytes or endothelial cells. In human CRC samples, all stromal signatures were strongly associated with the SSM subtype. A high CAF signature was associated with poor prognosis in untreated CRC patients, while in rectal cancer high stromal signatures jointly predicted radioresistance. These data show that the distinctive transcriptional and clinical features of the SSM subtype can be ascribed to its particularly abundant stroma. Citation Format: Claudio Isella, Andrea Terrasi, Sara E. Bellomo, Consalvo Petti, Andrea Muratore, Alfredo Mellano, Mark De Ridder, Paola Cassoni, Guy Storme, Andrea Bertotti, Enzo Medico. Stromal contribution to the colorectal cancer transcriptome. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4760. doi:10.1158/1538-7445.AM2015-4760