A PRRX1 Signature Identifies TIM-3 and VISTA as Potential Immune Checkpoint Targets in a Subgroup of Microsatellite Stable Colorectal Cancer Liver Metastases.

Disease recurrence and drug resistance are major challenges in the clinical management of patients with colorectal cancer liver metastases (CLM), and because tumors are generally microsatellite stable (MSS), responses to immune therapies are poor. The mesenchymal phenotype is overrepresented in treatment-resistant cancers and is associated with an immunosuppressed microenvironment. The aim of this work was to molecularly identify and characterize a mesenchymal subgroup of MSS CLM to identify novel therapeutic approaches. We here generated a mesenchymal gene expression signature by analysis of resection specimens from 38 patients with CLM using ranked expression level of the epithelial-to-mesenchymal transition-related transcription factor PRRX1. Downstream pathway analysis based on the resulting gene signature was performed and independent, publicly available datasets were used to validate the findings. A subgroup comprising 16% of the analyzed CLM samples were classified as mesenchymal, or belonging to the PRRX1 high group. Analysis of the PRRX1 signature genes revealed a distinct immunosuppressive phenotype with high expression of immune checkpoints HAVCR2/TIM-3 and VISTA, in addition to the M2 macrophage marker CD163. The findings were convincingly validated in datasets from three external CLM cohorts. Upregulation of immune checkpoints HAVCR2/TIM-3 and VISTA in the PRRX1 high subgroup is a novel finding, and suggests immune evasion beyond the PD-1/PD-L1 axis, which may contribute to poor response to PD-1/PD-L1-directed immune therapy in MSS colorectal cancer. Importantly, these checkpoints represent potential novel opportunities for immune-based therapy approaches in a subset of MSS CLM. Significance: CLM is an important cause of colorectal cancer mortality where the majority of patients have yet to benefit from immunotherapies. In this study of gene expression profiling analyses, we uncovered novel immune checkpoint targets in a subgroup of patients with MSS CLMs harboring a mesenchymal phenotype.

Low Concordance Between T-Cell Densities in Matched Primary Tumors and Liver Metastases in Microsatellite Stable Colorectal Cancer.

BACKGROUND: The subtype, density and location of tumor infiltrating T-cells are being explored as prognostic and predictive biomarkers in primary colorectal cancer (pCRC) and colorectal liver metastases (CLM). Very limited data exist comparing findings in pCRC and matched CLM. PATIENTS AND METHODS: Fifty-eight patients with available pCRC and matched CLM (57/58 microsatellite stable) were included in this OSLO-COMET substudy. In immunohistochemically stained sections, total (Ttot), helper (TH), cytotoxic (CTL), and regulatory (Treg) T-cells were manually counted in hotspots from the invasive margin (IM), intratumor (IT), and tumor adjacent regions to determine T-cell densities. RESULTS: A striking accumulation of T-cells was found in IM of both pCRC and CLM with much lower densities in the IT region, exemplified by Ttot of 2838 versus 340 cells/mm2, respectively, in CLM. The correlation at the individual level between T-cell densities in pCRC and corresponding CLM was poor for all regions and T-cell subtypes; for instance, the correlation coefficient (R2) for IM Ttot was 0.07. The IT TH : CTL and Treg : TH ratios were 2.94 and 0.44, respectively, in pCRC, and 1.84 and 0.24, respectively, in CLM. CONCLUSION: The observed accumulation of T-cells in the IM regions of pCRC and CLM with low penetration to the IT regions, combined with high TH : CTL and Treg : TH ratios, point to the presence of an immune suppressive microenvironment. T-cell densities of CLM differed markedly from the matched pCRC, indicating that to evaluate T-cell biomarkers in metastasis, the commonly available pCRC cannot serve as a surrogate for the metastatic tumor.

Long-Term Oncologic Outcomes After Laparoscopic Versus Open Resection for Colorectal Liver Metastases : A Randomized Trial.

BACKGROUND: Despite the recent worldwide dissemination of laparoscopic liver surgery, no high-level evidence supports the oncologic safety of this approach. OBJECTIVE: To evaluate long-term oncologic outcomes after laparoscopic versus open liver resection in patients with colorectal metastases. DESIGN: A single-center, assessor-blinded, randomized controlled trial (OSLO-COMET [Oslo Randomized Laparoscopic Versus Open Liver Resection for Colorectal Metastases Trial]). (ClinicalTrials.gov: NCT01516710). SETTING: Oslo University Hospital, the only provider of liver surgery for the 3 million inhabitants of southeastern Norway. PARTICIPANTS: Patients with resectable colorectal liver metastases were randomly assigned to have open or laparoscopic liver resection. INTERVENTION: From February 2012 to January 2016, a total of 280 patients were included in the trial (laparoscopic surgery: n = 133; open surgery: n = 147). MEASUREMENTS: The primary outcome was postoperative morbidity within 30 days. Five-year rates of overall and recurrence-free survival were predefined secondary end points. RESULTS: At a median follow-up of 70 months, rates of 5-year overall survival were 54% in the laparoscopic group and 55% in the open group (between-group difference, 0.5 percentage point [95% CI, -11.3 to 12.3 percentage points]; hazard ratio, 0.93 [CI, 0.67 to 1.30]; P = 0.67). Rates of 5-year recurrence-free survival were 30% in the laparoscopic group and 36% in the open group (between-group difference, 6.0 percentage points [CI, -6.7 to 18.7 percentage points]; hazard ratio, 1.09 [CI, 0.80 to 1.49]; P = 0.57). LIMITATION: The trial was not powered to detect differences in secondary end points and was not designed to address a noninferiority hypothesis for survival outcomes. CONCLUSION: In this randomized trial of laparoscopic and open liver surgery, no difference in survival outcomes was found between the treatment groups. However, differences in 5-year overall survival up to about 10 percentage points in either direction cannot be excluded. This trial should be followed by pragmatic multicenter trials and international registries. PRIMARY FUNDING SOURCE: The South-Eastern Norway Regional Health Authority.

Neoadjuvant chemotherapy is associated with a transient increase of intratumoral T-cell density in microsatellite stable colorectal liver metastases.

Patients with colorectal liver metastases (CLM) commonly receive neoadjuvant chemotherapy (NACT) prior to surgical resection. NACT may induce immunogenic cell death with subsequent recruitment of T-cells to the tumor microenvironment, which could be exploited by immune checkpoint inhibition (ICI). In theory, this could expand the use of ICI to obtain responses also in microsatellite stable colorectal cancer, but evidence to suggest optimal treatment schedules are lacking. In this study, densities of total-, cytotoxic-, helper- and regulatory T-cells were quantified by immunohistochemistry in resected CLM from 92 patients included in the OSLO-COMET trial (NCT01516710). All but one patient had microsatellite stable tumors (91/92). Associations between T-cell densities and clinicopathological parameters were analyzed. Fluoropyrimidine-based NACT (in most cases with addition of oxaliplatin or irinotecan) was administered to 45 patients completed median 8 weeks prior to surgical resection. No overall association was found between NACT administration and intratumoral T-cell densities. However, within the NACT group, a short time interval (<9.5 weeks) between NACT completion and CLM resection was strongly associated with high intratumoral T-cell densities compared to the long-interval and no NACT groups (medians 491, 236, and 292 cells/mm2, respectively; P < .0001). The results from this study suggest that the observed increase in intratumoral T-cells after NACT administration may be transient. The significance of this finding should be further explored to ensure that optimal treatment schedules are chosen for studies combining cytotoxic chemotherapy and ICI.

Intravenous Patient-controlled Analgesia Versus Thoracic Epidural Analgesia After Open Liver Surgery: A Prospective, Randomized, Controlled, Noninferiority Trial.

OBJECTIVE: We conducted a randomized, controlled, noninferiority trial to investigate if intravenous, multimodal, patient-controlled analgesia (IV-PCA) could be noninferior to multimodal thoracic epidural analgesia (TEA) in patients undergoing open liver surgery. SUMMARY BACKGROUND DATA: The increasing use of minimally invasive techniques and fast track protocols have questioned the position of epidural analgesia as the optimal method of pain management after abdominal surgery. METHODS: Patients operated with open liver resection between February 2012 and February 2016 were randomly assigned to receive either IV-PCA enhanced with ketorolac/diclofenac (IV-PCA, n = 66) or TEA (n = 77) within an enhanced recovery after surgery protocol. Noninferiority would be declared if the mean pain score on the numeric rating scale (NRS) for postoperative days (PODs) 0 to 5 in the IV-PCA group was no worse than the mean pain score in the TEA group by a margin of <1 point on an 11-point scale (0-10). RESULTS: The primary endpoint, mean NRS pain score was 1.7 in the IV-PCA group and 1.6 in the TEA group, establishing noninferiority. Pain scores were lower in the TEA group on PODs 0 and 1, but higher or equal on PODs 2 and 5. Postoperative hospital stay was significantly shorter for patients in the IV-PCA group (74 vs 104 h, P < 0.001). The total opioid consumption during the first 3 days was significantly lower in the IV-PCA group. CONCLUSIONS: IV-PCA was noninferior to TEA for the treatment of postoperative pain in patients undergoing open liver resection.

Laparoscopic Versus Open Resection for Colorectal Liver Metastases: The OSLO-COMET Randomized Controlled Trial.

OBJECTIVE: To perform the first randomized controlled trial to compare laparoscopic and open liver resection. SUMMARY BACKGROUND DATA: Laparoscopic liver resection is increasingly used for the surgical treatment of liver tumors. However, high-level evidence to conclude that laparoscopic liver resection is superior to open liver resection is lacking. METHODS: Explanatory, assessor-blinded, single center, randomized superiority trial recruiting patients from Oslo University Hospital, Oslo, Norway from February 2012 to January 2016. A total of 280 patients with resectable liver metastases from colorectal cancer were randomly assigned to undergo laparoscopic (n = 133) or open (n = 147) parenchyma-sparing liver resection. The primary outcome was postoperative complications within 30 days (Accordion grade 2 or higher). Secondary outcomes included cost-effectiveness, postoperative hospital stay, blood loss, operation time, and resection margins. RESULTS: The postoperative complication rate was 19% in the laparoscopic-surgery group and 31% in the open-surgery group (12 percentage points difference [95% confidence interval 1.67-21.8; P = 0.021]). The postoperative hospital stay was shorter for laparoscopic surgery (53 vs 96 hours, P < 0.001), whereas there were no differences in blood loss, operation time, and resection margins. Mortality at 90 days did not differ significantly from the laparoscopic group (0 patients) to the open group (1 patient). In a 4-month perspective, the costs were equal, whereas patients in the laparoscopic-surgery group gained 0.011 quality-adjusted life years compared to patients in the open-surgery group (P = 0.001). CONCLUSIONS: In patients undergoing parenchyma-sparing liver resection for colorectal metastases, laparoscopic surgery was associated with significantly less postoperative complications compared to open surgery. Laparoscopic resection was cost-effective compared to open resection with a 67% probability. The rate of free resection margins was the same in both groups. Our results support the continued implementation of laparoscopic liver resection.

Molecular signatures reflecting microenvironmental metabolism and chemotherapy-induced immunogenic cell death in colorectal liver metastases.

Background: Metastatic colorectal cancer (CRC) is associated with highly variable clinical outcome and response to therapy. The recently identified consensus molecular subtypes (CMS1-4) have prognostic and therapeutic implications in primary CRC, but whether these subtypes are valid for metastatic disease is unclear. We performed multi-level analyses of resectable CRC liver metastases (CLM) to identify molecular characteristics of metastatic disease and evaluate the clinical relevance. Methods: In this ancillary study to the Oslo-CoMet trial, CLM and tumor-adjacent liver tissue from 46 patients were analyzed by profiling mutations (targeted sequencing), genome-wide copy number alteration (CNAs), and gene expression. Results: Somatic mutations and CNAs detected in CLM were similar to reported primary CRC profiles, while CNA profiles of eight metastatic pairs suggested intra-patient divergence. A CMS classifier tool applied to gene expression data, revealed the cohort to be highly enriched for CMS2. Hierarchical clustering of genes with highly variable expression identified two subgroups separated by high or low expression of 55 genes with immune-related and metabolic functions. Importantly, induction of genes and pathways associated with immunogenic cell death (ICD) was identified in metastases exposed to neoadjuvant chemotherapy (NACT). Conclusions: The uniform classification of CLM by CMS subtyping may indicate that novel class discovery approaches need to be explored to uncover clinically useful stratification of CLM. Detected gene expression signatures support the role of metabolism and chemotherapy in shaping the immune microenvironment of CLM. Furthermore, the results point to rational exploration of immune modulating strategies in CLM, particularly by exploiting NACT-induced ICD.