Identification of Colorectal Cancer Cell Stemness from Single-Cell RNA Sequencing

Cancer stem cells (CSC) play a critical role in metastasis, relapse, and therapy resistance in colorectal cancer. While characterization of the normal lineage of cell development in the intestine has led to the identification of many genes involved in the induction and maintenance of pluripotency, recent studies suggest significant heterogeneity in CSC populations. Moreover, while many canonical colorectal cancer CSC marker genes have been identified, the ability to use these classical markers to annotate stemness at the single-cell level is limited. In this study, we performed single-cell RNA sequencing on a cohort of 6 primary colon, 9 liver metastatic tumors, and 11 normal (nontumor) controls to identify colorectal CSCs at the single-cell level. Finding poor alignment of the 11 genes most used to identify colorectal CSC, we instead extracted a single-cell stemness signature (SCS_sig) that robustly identified "gold-standard" colorectal CSCs that expressed all marker genes. Using this SCS_sig to quantify stemness, we found that while normal epithelial cells show a bimodal distribution, indicating distinct stem and differentiated states, in tumor epithelial cells stemness is a continuum, suggesting greater plasticity in these cells. The SCS_sig score was quite variable between different tumors, reflective of the known transcriptomic heterogeneity of CRC. Notably, patients with higher SCS_sig scores had significantly shorter disease-free survival time after curative intent surgical resection, suggesting stemness is associated with relapse.

IMPLICATIONS

This study reveals significant heterogeneity of expression of genes commonly used to identify colorectal CSCs, and identifies a novel stemness signature to identify these cells from scRNA-seq data.

Gastric Extent of Tumor Predicts Peritoneal Metastasis in Siewert II Adenocarcinoma

BACKGROUND

Whereas current guidelines recommend staging laparoscopy for most patients with potentially resectable gastric cancer, such a recommendation for patients with adenocarcinoma of the gastroesophageal junction (AEG) is lacking. This study sought to identify baseline clinicopathologic characteristics associated with peritoneal metastasis (PM) among patients with Siewert II AEG.

METHODS

Trimodality therapy-eligible patients with Siewert II AEG (2000-2015, single institution) were retrospectively identified. A composite PM outcome was defined as follows: (1) PM at staging laparoscopy; (2) PM diagnosed during neoadjuvant chemoradiation; or (3) PM ≤6 months postoperatively. Logistic regression was used to identify features associated with PM; bootstrapped analysis (Youden J) identified the distal tumor extension that best discriminated the composite outcome.

RESULTS

Of 188 patients, a composite PM outcome was observed in 26 of 188 (13.8%); 12 of 26 had positive staging laparoscopy, 10 of 26 experienced PM during chemoradiation, and 4 of 26 had PM ≤6 months postoperatively. Tumor extension below the GEJ was greater in patients with PM (median, 4.0 cm [interquartile range, 3.0-5.0] vs 3.0 cm [interquartile range, 2.0-3.0]; P < .001). All patients with PM had cT3 to cT4 tumors. Among patients with cT3 to cT4 tumors (n = 168 of 188; 89.4%), distal tumor extent (odds ratio, 1.67/cm; 95% CI, 1.23-2.28; P = .001) was independently associated with increased odds of PM. Gastric tumor extension ≥4 cm remained independently associated with PM (OR, 5.14; 95% CI, 2.11-12.53; P < .001) after adjustment for signet ring cell status.

CONCLUSIONS

Distal tumor extent beyond the GEJ is independently associated with increased odds of PM in patients with Siewert II AEG. Patients with extensive gastric involvement should therefore be considered for staging laparoscopy before trimodality therapy.

TP53 Alteration and Its Effect on Pathologic Response Are Associated with Survival after Resection of Colorectal Liver Metastases

The aims of this study were to assess the effect of known gene alterations (RAS, TP53, APC, SMAD4, BRAF, and FBXW7) on pathologic response (PR) and their combined association with survival in patients with colorectal liver metastases (CLM). From a prospectively maintained database, we collected data on 458 patients who underwent curative-intent hepatectomy after receiving the first-line preoperative chemotherapy between 2004 and 2020. Major PR was defined as tumor viability of less than 50% in all tumors. Multivariate logistic regression revealed that oxaliplatin-containing regimen (OR: 2.54, 95% CI: 1.58-4.07, P < 0.001), bevacizumab-containing regimen (OR: 2.15, 95%CI: 1.36-3.39, P = 0.001), and TP53 alteration (OR: 0.42, 95%CI: 0.27-0.66, P < 0.001) were independently associated with major PR. Multivariate Cox regression also revealed that patients with TP53 wild-type and major PR (HR: 0.49, 95%CI: 0.31-0.77, P = 0.002) and those with TP53 alteration and major PR (HR: 0.70, 95%CI: 0.49-1.00, P = 0.048) had significantly better overall survival compared to those with minor PR. Further studies targeting the association of TP53 with PR and survival can help clarify the role of TP53 in CLM.

New Insights into Macrophage Polarization and its Prognostic Role in Patients with Colorectal Cancer Liver Metastasis

Background

As liver metastasis is the most common cause of mortality in patients with colorectal cancer, studying colorectal cancer liver metastasis (CLM) microenvironment is essential for improved understanding of tumor biology and to identify novel therapeutic targets.

Methods

We used multiplex immunofluorescence platform to study tumor associated macrophage (TAM) polarization and adaptive T cell subtypes in tumor samples from 105 CLM patients (49 without and 56 with preoperative chemotherapy).

Results

CLM exhibited M2 macrophage polarization, and helper T cells were the prevalent adaptive T cell subtype. The density of total, M2 and TGFβ-expressing macrophages, and regulatory T cells was lower in CLM treated with preoperative chemotherapy. CLM with right-sided primary demonstrated enrichment of TGFβ-expressing macrophages, and with left-sided primary had higher densities of helper and cytotoxic T cells. In multivariate analysis, high density of M2 macrophages correlated with longer recurrence-free survival (RFS) in the entire cohort [hazard ratio (HR) 0.425, 95% CI 0.219-0.825, p=0.011) and in patients without preoperative chemotherapy (HR 0.45, 95% CI 0.221-0.932, p=0.032). High pSMAD3-expressing macrophages were associated with shorter RFS in CLM after preoperative chemotherapy.

Conclusions

Our results highlight the significance of a multi-marker approach to define the macrophage subtypes and identify M2 macrophages as a predictor of favorable prognosis in CLM.

ANPEP/CD13 Expression as a Marker of Lymphovascular Invasion and Survival in Esophageal Adenocarcinoma

BACKGROUND

The presence of lymphovascular invasion (LVI) in early esophageal adenocarcinoma (EAC) is associated with more aggressive disease. Molecular markers associated with LVI are still largely unknown. Using a combination of transcriptomic analysis and validation experiments, we sought to describe markers for LVI and survival.

METHODS

We performed NanoString expression profiling using RNA from 60 EAC specimens collected from surgery-only cases between 2000 and 2012. Differentially expressed genes (DEGs) were correlated with pathologic characteristics (T and N status and presence of LVI). Kaplan-Meier and Cox regression analyses were used to correlate gene expression with overall survival. Expression of alanyl aminopeptidase, membrane (ANPEP)/CD13 was validated by immunohistochemistry (IHC) in EAC tissue microarray and in EAC cell lines.

RESULTS

We identified >20 up-regulated DEGs in tumor samples containing LVI. Multivariable analysis showed depth of invasion and ANPEP/CD13 expression were independently associated with overall survival, whereas nodal status was not. IHC analysis demonstrated overexpression of the ANPEP/CD13 protein in dysplastic Barrett esophagus and EAC tumors. Kaplan-Meier analysis showed that patients with higher RNA expression and strongly positive ANPEP/CD13 membrane IHC-Histoscore staining have shorter survival (P = .002). Down-regulation of ANPEP/CD13 expression by short hairpin RNA vector reduces colony formation, migration, and invasion of FLO-1 EAC cells. Overexpression of CD13 in SKGT4 EAC cells increases colony formation, motility, and invasion in vitro.

CONCLUSIONS

Elevated expression of ANPEP/CD13 indicates shorter survival of EAC patients and a more invasive phenotype of cancer cells in vitro. Validation in a larger sample group is required to better understand the clinical significance of ANPEP/CD13 and other candidate genes.

Exploratory study of macrophage polarization and spatial distribution in colorectal cancer liver metastasis: a pilot study

Background

The liver is the most typical site of metastatic disease for patients with colorectal cancer (CRC), and up to half the patients with CRC will develop colorectal liver metastasis (CLM). Studying the tumor microenvironment, particularly macrophages and their spatial distribution, can give us critical insight into treatment.

Methods

Ten CLMs (five treatment-naïve and five post-neoadjuvant chemotherapy) were stained with multiplex immunofluorescence panels against cytokeratins, CD68, Arg1, CD206, CD86, CD163, PD-L1, and MRP8-14. Densities of cell phenotypes and their spatial distribution in the tumor center and the normal liver-tumor interface were correlated with clinicopathological variables.

Results

M2 macrophages were the predominant subtype in both the tumor center and the periphery, with a relatively higher density at the periphery. The larger tumors, more than 3.9 cm, were associated with higher densities of total CD68+ macrophages and CD68+CD163+ CD206neg and CD68+CD206+ CD163neg M2 macrophage subtypes. Total macrophages in the tumor periphery demonstrated significantly greater proximity to malignant cells than did those in the tumor center (p=0.0371). The presence of higher than median CD68+MRP8-14+CD86neg M1 macrophages in the tumor center was associated with poor overall survival (median 2.34 years) compared to cases with lower than median M1 macrophages at the tumor center (median 6.41 years) in univariate analysis.

Conclusion

The dominant polarization of the M2 macrophage subtype could drive new therapeutic approaches in CLM patients.

Spatial molecular and cellular determinants of STAT3 activation in liver fibrosis progression in non-alcoholic fatty liver disease

Background & Aims

The prevalence of non-alcoholic fatty liver disease (NAFLD) and its severe form, non-alcoholic steatohepatitis (NASH), is increasing. Individuals with NASH often develop liver fibrosis and advanced liver fibrosis is the main determinant of mortality in individuals with NASH. We and others have reported that STAT3 contributes to liver fibrosis and hepatocellular carcinoma in mice.

Methods

Here, we explored whether STAT3 activation in hepatocyte and non-hepatocyte areas, measured by phospho-STAT3 (pSTAT3), is associated with liver fibrosis progression in 133 patients with NAFLD. We further characterized the molecular and cellular determinants of STAT3 activation by integrating spatial distribution and transcriptomic changes in fibrotic NAFLD livers.Results: pSTAT3 scores in non-hepatocyte areas progressively increased with fibrosis severity (r = 0.53, p <0.001). Correlation analyses between pSTAT3 scores and expression of 1,540 immune- and cancer-associated genes revealed a large effect of STAT3 activation on gene expression changes in non-hepatocyte areas and confirmed a major role for STAT3 activation in fibrogenesis. Digital spatial transcriptomic profiling was also performed on 13 regions selected in hepatocyte and non-hepatocyte areas from four NAFLD liver biopsies with advanced fibrosis, using a customized panel of markers including pSTAT3, PanCK+CK8/18, and CD45. The regions were further segmented based on positive or negative pSTAT3 staining. Cell deconvolution analysis revealed that activated STAT3 was enriched in hepatic progenitor cells (HPCs) and sinusoidal endothelial cells. Regression of liver fibrosis upon STAT3 inhibition in mice with NASH resulted in a reduction of HPCs, demonstrating a direct role for STAT3 in HPC expansion.

Conclusion

Increased understanding of the spatial dependence of STAT3 signaling in NASH and liver fibrosis progression could lead to novel targeted treatment approaches.

Impact and implications

Advanced liver fibrosis is the main determinant of mortality in patients with NASH. This study showed using liver biopsies from 133 patients with NAFLD, that STAT3 activation in non-hepatocyte areas is strongly associated with fibrosis severity, inflammation, and progression to NASH. STAT3 activation was enriched in hepatic progenitor cells (HPCs) and sinusoidal endothelial cells (SECs), as determined by innovative technologies interrogating the spatial distribution of pSTAT3. Finally, STAT3 inhibition in mice resulted in reduced liver fibrosis and depletion of HPCs, suggesting that STAT3 activation in HPCs contributes to their expansion and fibrogenesis in NAFLD.

A phase II randomized double blinded trial evaluating the efficacy of curcumin with pre-operative chemoradiation for rectal cancer

Background

In vivo studies demonstrate that curcumin increases radioresponse of colorectal cancers. To demonstrate efficacy in humans, we performed a randomized double-blind study of locally advanced rectal cancer (LARC) patients receiving pre-operative chemoradiation therapy (CRT) ± curcumin. We used pathologic complete response (pCR) rate as a surrogate for clinical outcome.

Methods

From 2008-2010, LARC patients were randomized to placebo/curcumin in a 1:2 ratio. Patients received CRT [50.4 gray in 28 fractions; capecitabine (825 mg/m² twice daily)] followed by surgery. Curcumin (4 grams orally, twice daily) or placebo was given throughout CRT and 6 weeks afterward. Toxicity was monitored weekly. Blood samples taken pre- and 1-hour post-ingestion and tissue biopsies (both collected at CRT week 2) were analyzed for pharmacokinetics. The primary outcome was surgical pCR rate.

Results

Of 22 enrolled patients, 15 received curcumin. Median age was 61 years and the majority were male (n=13; 59%). The median serum curcumin concentrations before (3.04 ng/mL; range, 1.24-18.88 ng/mL) and 1 hour after (3.32 ng/mL; range, 0.84-5.36 ng/mL) curcumin intake did not differ significantly (P=0.33). Serum curcumin concentrations both increased and decreased 1-hour post-administration (range as percentage of baseline: 8.8-258.1%). Twelve curcumin patient tissue biopsies had median curcumin concentration of 33.7 ng/mg tissue (range, 0.1-4,765.7 ng/mg). Two placebo and 1 curcumin patient achieved pCRs (P=0.18). One grade 3 toxicity (infection) was experienced.

Conclusions

The addition of curcumin to CRT did not increase pCR rates for LARC patients. The unpredictable bioavailability of curcumin contributes to continued uncertainties regarding curcumin efficacy.

Trial Registration

ClinicalTrials.gov identifier: NCT00745134.

Colorectal Liver Micrometastases: Association with RAS/TP53 Co-Mutation and Prognosis after Surgery

BACKGROUND

Micrometastases, defined as microscopic cancer cells spatially separated from the macroscopically evident metastasis, are identified in 24% to 56% of resected colorectal liver metastases (CLMs). Somatic gene mutations have emerged as independent prognostic factors in CLM. This study aimed to determine the prognostic impact and risk factors for the presence of micrometastases, including somatic gene mutations.

STUDY DESIGN

Prospective evaluation for micrometastases was performed at 2 centers in the US and France from 2015 to 2019. CLM specimens were cut radially from the tumor margin to surrounding grossly normal liver for a distance of 2 cm. Depending on CLM size, 3 to 8 specimens per patient were submitted for microscopic analysis. Somatic gene mutations were detected by next-generation sequencing.

RESULTS

Among 140 patients undergoing CLM resection in the US (n = 84) and France (n = 56), 36 (26%) patients were found to have micrometastases. Five-year overall and recurrence-free survival rates with micrometastases were 39% and 0%, respectively, compared with 61% and 20% without micrometastases (both p < 0.05). In multivariable analyses, the presence of micrometastases was an independent risk factor for worse overall survival (hazard ratio 2.88, 95% CI 1.46 to 5.70, p = 0.002) and recurrence-free survival (hazard ratio 1.56, 95% CI 1.01 to 2.41, p = 0.046). In binary logistic regression analysis, RAS/TP53 co-mutation was found to significantly increase the risk of micrometastases (odds ratio 2.77, 95% CI 1.15 to 6.71, p = 0.024).

CONCLUSIONS

Micrometastases are associated with significantly worse survival after CLM resection. RAS/TP53 co-mutation correlated with increased risk of micrometastases. Further studies are needed to determine strategies to eradicate micrometastases.

Impact of consensus molecular subtyping (CMS) on survival in the CO.26 trial of durvalumab plus tremelimumab versus best supportive care (BSC) in metastatic colorectal cancer (mCRC)

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Background: CO.26 was a phase 2 trial (2-sided α=0.1 and 80% power) that randomized 180 patients with refractory mCRC 2:1 to durvalumab + tremelimumab vs BSC with improved overall survival (OS) (HR 0.73, 90%CI 0.55-0.97, P=0.07). A Nanostring assay validated for use with FFPE was used to determine CMS for correlation with outcome. Methods: Archival FFPE from 163/180 (91%) of patients (pts) underwent RNA extraction and CMS subtyping. Cox proportional hazard models evaluated the prognostic and predictive impact of CMS on overall survival. Results: CMS distribution was skewed towards CMS4 (76%), with lower prevalence of CMS1 (2%), CMS2 (16%) and CMS3 (2%). There were 7/163 cases of indeterminate CMS (4%). Subgroup analysis was restricted to CMS2 and CMS4 based on sample size. With BSC alone, CMS2 showed trends to worse OS compared to all other patients pooled (HR 1.93, 90% CI 1.03-3.61, P=0.085), while CMS4 did not (HR 0.86, 90% CI 0.50-1.48, P=0.64). OS but not progression free survival (PFS) was improved with durvalumab + tremelimumab in the overall population. OS was improved with durvalumab + tremelimumab among patients with CMS2 tumors (HR 0.39, 90% CI 0.19-0.82, P=0.035) but not in patients with CMS4 tumors (HR 0.73, 90% CI 0.52-1.02, P=0.12) compared to BSC. Neither CMS2 (P-interaction=0.37) nor CMS4 (P-interaction=0.91) were predictive of OS benefit from durvalumab + tremelimumab compared to BSC. Disease control rate (DCR) trended to being better among CMS4 (24/85) than CMS2 cancers (1/15, OR 5.51, 90% CI 1.10-29.88, P=0.11) or CMS4 vs all non CMS4 cancers (1/21, OR 7.87, 90% CI 1.65-41.98, P=0.023) for patients on durvalumab + tremelimumab. PFS was not improved with durvalumab + tremelimumab in CMS2 (P=0.19) or CMS4 (P=0.29) cancers relative to BSC. Conclusions: In this trial of refractory colorectal cancer, we saw a shift in CMS subtype with more CMS4 than expected. Compared to CMS4, CMS2 showed stronger signals towards improved OS with durvalumab + tremelimumab but had a lower disease control rate. Differences in immune signaling by CMS may be important determinants of which component of immune regulation needs to be targeted in mCRC to improve outcomes. Clinical trial information: NCT02870920. [Table: see text]

HER3 expression in metastatic colorectal cancer: Defining the clinicomolecular profile of an emerging target

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Background: The success of tailored systemic therapies in treating distinct molecular subsets of patients (e.g., deficient mismatch repair, BRAF mutant, HER2 amplified) has spurred further exploration of novel targetable subsets within the heterogeneous landscape of metastatic colorectal cancer (mCRC). Human epidermal growth factor receptor 3 [HER3 (ErbB3)], a member of the HER (ErbB) receptor tyrosine kinase family, plays an important role in tumorigenesis and metastases and has emerged as a promising therapeutic target in a diverse array of cancers. For example, patritumab deruxtecan (U3-1402; HER3-DXd) is a HER3-directed antibody drug conjugate that has demonstrated clinically meaningful antitumor activity and acceptable safety profiles in metastatic breast cancer and EGFR-mutated non-small cell lung cancer. There is limited data, however, on the clinicopathological characterization of HER3 expression in mCRC. Methods: Tissue samples (surgical-metastatectomy) (N = 115) were obtained from a clinical cohort of patients (N = 99) with histologically proven mCRC and liver metastases who underwent liver resection with/without perioperative systemic chemotherapy. HER3 expression was analyzed on whole-mount preparations by immunohistochemistry (IHC). Staining was performed and visualized using the HER3 (D22C5) XP Rabbit-mAb (Cell Signaling Technology). Patients were categorized based on membranous intensity score as follows: Low with IHC 0 (absence of staining or staining in < 10% of tumor cells), 1+ (faint/barely perceptible staining in ≥10% of tumor cells) or 2+ (weak to moderate staining in ≥10% of tumor cells), or High with IHC 3+ (strong staining in ≥10% of tumor cells). Clinicomolecular and treatment data, including gender, tumor sidedness, mutational status (RAS or BRAF), and prior chemotherapy were collected by review of patient electronic medical records. Chi-squared (or Fisher’s exact) test were used to determine associations between groups. Overall survival (OS) was calculated using Kaplan-Meier method and compared using log-rank tests. Results: Among 99 analyzed patients, 98 were evaluable for HER3 expression. Of these 25.5%, 26.5%, 40.8% and 7.2% showed HER3 IHC scores of 3+, 2+, 1+ and 0, respectively. No significant association was seen with HER3 expression and clinicopathological variables, mutational status, or prior treatment. Among patients with 2 samples analyzed from the same liver surgery, there was a moderate level of heterogeneity with concordance of 78.5% (kappa 0.43). Patients with high HER3 expression had poorer OS (5-year OS: 52%; median: 90.2 months) compared to low HER3 expression (5-year OS: 85%; median: not reached). Conclusions: In this large cohort of mCRC, HER3 expression was observed in 92.8% of patients and across diverse clinical and molecular features, supporting HER3 as a promising targetable biomarker in a large subset of mCRC.

Outcomes of IBD-associated colorectal cancer and implications in early-onset colorectal cancer

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Background: Inflammatory bowel disease (IBD) increases the risk of developing colorectal cancer (CRC), and colitis-associated CRC (CA-CRC) mortality is on the rise. It has been postulated that CA-CRC may be contributing to the increasing prevalence of early-onset CRC (EOCRC) but supportive studies are currently lacking. Molecular and clinical differences between CA-CRC and sporadic-CRC (S-CRC) have been reported, however outcomes for CA-CRC remains unclear. Signet ring cell carcinoma (SRC) is a rare subtype of CRC which is seen at higher frequencies, along with mucinous histology, in both CA-CRC and EOCRC. In this study, we validate the association of SRC and mucinous (SRC/M) histology with CA-CRC and EOCRC, and utilize it to estimate the amount of EOCRC attributable to undiagnosed or subclinical IBD. Methods: A retrospective study was conducted using three independent mCRC patient datasets from MDACC. The mATTACC discovery cohort consisted of 32 IBD- and 425 S-mCRC patients enrolled in a prospective biomarker trial. Validation of tumor histology was completed with a tumor registry (n=1696), excluding the MSI-High samples, and a real-world evidence (RWE) cohort from MDACC containing 269 CA-mCRC and 29,596 S-mCRC patients, was used as our validation cohort. Results: In the mATTACC cohort SRC/M histology was found in 37.5% of CA-mCRC and 11.7% of S-mCRC, showing a strong association between SRC/M and CA-mCRC (OR = 4.54, 95% CI: 2.19-9.43). The RWE cohort confirmed the correlation of SRC/M with CA-mCRC (28.6%) relative to S-mCRC (11.4%) patients (OR = 3.13, 95%CI: 2.39-4.09). An association was found between SRC/M and EOCRC (OR = 1.35; 95% CI: 1.24-1.47). By comparing the prevalence of SRC/M in EOCRC and late-onset CRC and correcting by the proportion of CA-CRC cases with SRC/M histology, we estimate that between 8.28% to 10.15% of EOCRC may attributable to undiagnosed/subclinical IBD. Using the RWE cohort, median overall survival was determined to be lower for CA-mCRC (31m) relative to S-mCRC (39m; p=0.007), yielding a HR of 1.26 (95% CI: 1.06-1.48). CA-mCRC patients with EOCRC (25m) were also found to have significantly worse outcomes than S-mCRC patients (40m) with EOCRC (p=0.0005; HR = 1.61, 95%CI: 1.23-2.11). Within CA-mCRC, patients with SRC or SRC/M histology (21m) had decreased OS compared to mucinous histology (51m), indicating the poor prognosis of SRC in CA-mCRC (p=0.028; HR=0.53, 95% CI: 0.3-0.94). Conclusions: Tumor biology consistent with CA-CRC, including SRC/M histology, may be present in 8.3% – 10.2% of patients with EOCRC without a clinical diagnosis of IBD, and harbors worse outcomes. Although other confounding biology may be underlying this association, recognition of undiagnosed IBD in CRC patients, especially those with metastatic disease, is important as it may impact prognosis and treatment strategies for this high-risk patient population.

Efficacy, Safety and Biomarker Analysis of Combined PD-L1 (Atezolizumab) and VEGF (Bevacizumab) Blockade in Advanced Malignant Peritoneal Mesothelioma

Malignant peritoneal mesothelioma (MPeM) is a rare but aggressive malignancy with limited treatment options. VEGF inhibition enhances efficacy of immune-checkpoint inhibitors by reworking the immunosuppressive tumor milieu. Efficacy and safety of combined PD-L1 (atezolizumab) and VEGF (bevacizumab) blockade (AtezoBev) was assessed in 20 patients with advanced and unresectable MPeM with progression or intolerance to prior platinum-pemetrexed chemotherapy. The primary endpoint of confirmed objective response rate per RECISTv1.1 by independent radiology review was 40% (8/20; 95%CI:19.1-64.0) with median response duration of 12.8 months. Six (75%) responses lasted for >10 months. Progression-free and overall survival at 1-year were 61% (95%CI:35-80) and 85% (95%CI:60-95), respectively. Responses occurred notwithstanding low tumor mutation burden and PD-L1 expression status. Baseline epithelial-mesenchymal transition gene-expression correlated with therapeutic resistance/response (r=0.80; P=0.0010). AtezoBev showed promising and durable efficacy in patients with advanced MPeM with acceptable safety profile and these results address a grave unmet need for this orphan disease.

Pilot Clinical Trial of Perioperative Durvalumab and Tremelimumab in the Treatment of Resectable Colorectal Cancer Liver Metastases

PURPOSE

Despite the prognostic importance of immune infiltrate in colorectal cancer, immunotherapy has demonstrated limited clinical activity in refractory metastatic proficient mismatch-repair (pMMR) colorectal cancer. This study explores combining anti-CTLA-4 and an anti-PD-L1 therapy in the preoperative management of resectable colorectal cancer liver metastases with the intent to improve immune responses in this disease setting.

PATIENTS AND METHODS

Patients with resectable colorectal cancer liver-only metastases received one dose of tremelimumab and durvalumab preoperatively followed by single-agent durvalumab postoperatively. Primary objectives were to determine feasibility and safety.

RESULTS

A total of 24 patients were enrolled between November 2016 and November 2019. Twenty-three patients received treatment [21 pMMR and 2 deficient mismatch-repair (dMMR)] and subsequently 17 (74%; 95% CI: 53%-88%) underwent surgical resection. Grade 3/4 treatment-related immune toxicity and postoperative grade 3/4 toxicity were seen in 5/23 (22%; 95% CI: 10%-44%) and 2/17 (12%; 95% CI: 2%-38%) patients. The median relapse-free survival (RFS) was 9.7 (95% CI: 8.1-17.8) months, and overall survival was 24.5 (95% CI: 16.5-28.4) months. Four patients demonstrated complete pathologic response, two dMMR patients and two POLE mutation patients. Pre- and post-tumor tissue analysis by flow cytometry, immunofluorescence, and RNA sequencing revealed similar levels of T-cell infiltration, but did demonstrate evidence of CD8⁺ and CD4⁺ activation posttreatment. An increase in B-cell transcriptome signature and B-cell density was present in posttreatment samples from patients with prolonged RFS.

CONCLUSIONS

This study demonstrates the safety of neoadjuvant combination tremelimumab and durvalumab prior to colorectal cancer liver resection. Evidence for T- and B-cell activation following this therapy was seen in pMMR metastatic colorectal cancer.

Frequency and Implications of Paratracheal Lymph Node Metastases in Resectable Esophageal or Gastroesophageal Junction Adenocarcinoma

OBJECTIVE

We aimed to evaluate the frequency of paratracheal lymph nodes (LN) metastases and their prognostic influence.

SUMMARY BACKGROUND DATA

Paratracheal LNs are considered regional nodes in the esophageal cancer classification, but their metastatic rate and influence on survival remain unclear.

METHODS

One thousand one hundred ninety-nine patients with resectable esophageal or gastroesophageal junction adenocarcinoma (EAC) (January 2002 and December 2016) in our Gastrointestinal Medical Oncology Database were analyzed. Paratracheal LNs were defined as1R, 1L, 2R, 2L, 4R, and 4L, according to the 8th American Joint Committee on Cancer classification.

RESULTS

Of 1199 patients, 73 (6.1%) had positive paratracheal LNs at diagnosis. The median overall survival (OS) of 73 patients with initial paratracheal LN involvement was 2.10 years (range 0.01-10.1, 5-yrs OS 24.2%). Of 1071 patients who were eligible for recurrence evaluation, 70 patients (6.5%) developed paratracheal LN metastases as the first recurrence. The median time to recurrence was 1.28 years (range 0.28-5.96 yrs) and the median OS following recurrence was only 0.95 year (range 0.03-7.88). OS in 35 patients who had only paratracheal LN recurrence was significantly longer than in patients who had other recurrences (median OS 2.26 vs 0.51 yrs, 5-yrs OS; 26.8% vs 0%, P < 0.0001). Higher T stage (T3/T4) was an independently risk factor for paratracheal LN recurrence (odds ratio 5.10, 95% confidence interval 1.46-17.89). We segregated patients in 3 groups based on the distance of tumor's proximal edge to esophagogastric junction (low; ≤2 cm, medium; 2.0-7.0 cm, and high; >7.0 cm). Paratracheal LN metastases were more frequent with the proximal tumors (low, 4.2%; medium, 12.0%; high, 30.3%; Cochran-Armitage Trend test, P < 0.001).

CONCLUSION

Paratracheal LN metastases were associated with a shorter survival in resectable EAC patients. Alternate approaches to prolong survival of this group of patients are warranted.

Epigenetic regulation of the Wnt-signaling pathway in CIMP-H BRAFV600E mCRC

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Background: BRAFV600E mutation identifies mCRC patients with poor prognosis with only little benefit from standard therapy. Analysis from TCGA revealed that 89% of BRAFV600E CRC tumors were associated with a high CpG island methylator phenotype (CIMP-H), which may result in epigenetic silencing of tumor suppressor genes, while only 29% of BRAF wild-type tumors are CIMP-H. In this study, we define key pathways regulated by global DNA hypermethylation in the context of BRAFV600E mutation. Methods: We analyzed the TCGA Illumina 450k array methylation datasets and RNA-sequencing datasets for 97 CIMP-H CRC tumors (27 BRAFV600E; 69 BRAF WT) identified by five universal CIMP annotations ( p14, p16, MLH1, MINT1, MINT2, MINT31). We defined differential methylation profile according to BRAF mutation status and calculated Spearman correlation between methylation and gene expression to identify CIMP-H BRAF-associated genes. Next, pathways enriched with CIMP-H BRAFV600E tumors were defined using PANTHER pathway analysis. Additionally, β-catenin IHC were conducted on 145 MD Anderson CRC patient samples and compared by CIMP and BRAF status. Results: BRAF mutation is associated with lower rates of APC mutation as has previously been shown (32%, 82%). We identified 6,097 differentially methylated probes by BRAF mutation status (FDR = 10-4), and as expected, our data suggests a higher methylation profile in BRAFV600E mutated tumors compared to BRAF WT. Intriguingly, CIMP-H BRAF-associated genes showed enrichment in the Wnt-signaling and cadherin signaling pathways ( p< 0.0001 (FDR < 0.0001)). Despite the epigenetic Wnt-signaling, nuclear β-catenin expression (as a measure of Wnt activity) in CIMP-H and BRAF tumors remains lower than for non-CIMP, and BRAF wild-type ( p= 0.0003 for comparison of CIMP). Conclusions: Genes under methylation regulation in the BRAF-mutant context showed enrichment in Wnt-signaling pathway. Since BRAFV600E CRC tumors have a low association with APC mutation, this data suggests role of epigenetic regulation of the Wnt-pathway activation. However, as measured by nuclear β-catenin, Wnt activation in these tumors is not as high as traditional APC-mutated CRC tumors. CIMP-H tumors with BRAFV600E mutation is a unique subset of CRC tumor that have Wnt-pathway activation regulated by epigenetic modifications more than a β-catenin activation.

Phase II trial of bintrafusp alfa in patients with metastatic MSI-H cancers following progression on immunotherapy

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Background: Microsatellite instability-high (MSI-H) tumors are characterized by deficient mismatch repair, high tumor mutation burden, and exceptional anti-tumor responses to immunotherapy. While durable disease control is often observed for advanced MSI-H cancers treated with immune checkpoint blockade (ICB), some patients (pts) experience treatment resistance. In melanoma and urothelial cancer, acquired resistance to ICB has been associated with increased signaling of the immunosuppressive TGF-β pathway. Bintrafusp alfa (BA) is a first-in-class bifunctional fusion protein composed of the extracellular domain of the TGF-βRII receptor (a TGF-β “trap”) fused to a human IgG1 monoclonal antibody blocking PD-L1. Methods: In this phase II study (NCT03436563), pts with MSI-H metastatic solid tumors who had progressed on prior ICB were eligible. Pts received 1200 mg BA intravenously every 14 days. Paired tumor biopsies were collected for biomarker analysis. The primary objective was to estimate response rate (RR) per iRECIST. Median progression-free survival (PFS) and overall survival (OS) were calculated according to the Kaplan-Meier method. Adverse events (AEs) were assessed according to CTCAE v5.0. Results: 15 pts [arising from the colon/rectum (12), pancreas (1), duodenum (1), appendix (1)] were enrolled. Median duration of prior ICB before progression was 7.2 months (range, 1.8-24). All pts were evaluable for toxicity, and 14 for response. There was 1 grade 3 treatment-related AE (adrenal insufficiency) and 1 grade 5 treatment-related immune AE (hepatic failure). Median number of doses with BA was 4 (interquartile range, 2-4). There were 3 pts with stable disease and 11 with progressive disease as best response. RR was 0% (95% confidence interval (CI), 0-24%), and disease control rate was 21% (95% CI, 5-51%). Median PFS and OS were 1.8 months (95% CI, 1.5-5.7) and 9.1 months (95% CI, 5.3-not estimable), respectively. One pt with colorectal cancer demonstrated sustained stable disease (20.5 months) with BA. Conclusions: Dual inhibition of TGF-β and PD-L1 by BA did not demonstrate significant anti-tumor activity in the majority of pts with MSI-H metastatic cancer who had progressed on prior ICB. One pt did experience prolonged clinical benefit from BA. Ongoing correlative studies may inform on the effect of TGF-β and PD-L1 modulation by BA within the tumor microenvironment. Clinical trial information: NCT03436563.

ARID1A Mutation May Define an Immunologically Active Subgroup in Patients with Microsatellite Stable Colorectal Cancer

PURPOSE

AT-rich interactive domain 1A (ARID1A) is commonly mutated in colorectal cancer, frequently resulting in truncation and loss of protein expression. ARID1A recruits MSH2 for mismatch repair during DNA replication. ARID1A deficiency promotes hypermutability and immune activation in preclinical models, but its role in patients with colorectal cancer is being explored.

EXPERIMENTAL DESIGN

The DNA sequencing and gene expression profiling of patients with colorectal cancer were extracted from The Cancer Genome Atlas and MD Anderson Cancer Center databases, with validation utilizing external databases, and correlation between ARID1A and immunologic features. IHC for T-cell markers was performed on a separate cohort of patients.

RESULTS

Twenty-eight of 417 patients with microsatellite stable (MSS) colorectal cancer (6.7%) had ARID1A mutation. Among 58 genes most commonly mutated in colorectal cancer, ARID1A mutation had the highest increase with frameshift mutation rates in MSS cases (8-fold, P < 0.001). In MSS, ARID1A mutation was enriched in immune subtype (CMS1) and had a strong correlation with IFNγ expression (Δz score +1.91, P < 0.001). Compared with ARID1A wild-type, statistically significant higher expression for key checkpoint genes (e.g., PD-L1, CTLA4, and PDCD1) and gene sets (e.g., antigen presentation, cytotoxic T-cell function, and immune checkpoints) was observed in mutant cases. This was validated by unsupervised differential expression of genes related to immune response and further confirmed by higher infiltration of T cells in IHC of tumors with ARID1A mutation (P = 0.01).

CONCLUSIONS

The immunogenicity of ARID1A-mutant cases is likely due to an increased level of neoantigens resulting from increased tumor mutational burden and frameshift mutations. Tumors with ARID1A mutation may be more susceptible to immune therapy-based treatment strategies and should be recognized as a unique molecular subgroup in future immune therapy trials.

Development and Validation of a Gene Signature Classifier for Consensus Molecular Subtyping of Colorectal Carcinoma in a CLIA-Certified Setting

PURPOSE

Consensus molecular subtyping (CMS) of colorectal cancer has potential to reshape the colorectal cancer landscape. We developed and validated an assay that is applicable on formalin-fixed, paraffin-embedded (FFPE) samples of colorectal cancer and implemented the assay in a Clinical Laboratory Improvement Amendments (CLIA)-certified laboratory.

EXPERIMENTAL DESIGN

We performed an in silico experiment to build an optimal CMS classifier using a training set of 1,329 samples from 12 studies and validation set of 1,329 samples from 14 studies. We constructed an assay on the basis of NanoString CodeSets for the top 472 genes, and performed analyses on paired flash-frozen (FF)/FFPE samples from 175 colorectal cancers to adapt the classifier to FFPE samples using a subset of genes found to be concordant between FF and FFPE, tested the classifier's reproducibility and repeatability, and validated in a CLIA-certified laboratory. We assessed prognostic significance of CMS in 345 patients pooled across three clinical trials.

RESULTS

The best classifier was weighted support vector machine with high accuracy across platforms and gene lists (>0.95), and the 472-gene model outperforming existing classifiers. We constructed subsets of 99 and 200 genes with high FF/FFPE concordance, and adapted FFPE-based classifier that had strong classification accuracy (>80%) relative to "gold standard" CMS. The classifier was reproducible to sample type and RNA quality, and demonstrated poor prognosis for CMS1-3 and good prognosis for CMS2 in metastatic colorectal cancer (P < 0.001).

CONCLUSIONS

We developed and validated a colorectal cancer CMS assay that is ready for use in clinical trials, to assess prognosis in standard-of-care settings and explore as predictor of therapy response.

Esophageal adenocarcinoma with any component of signet ring cells portends poor prognosis and response to neoadjuvant therapy

BACKGROUND

Multiple investigations have shown inferior outcomes for esophageal cancer patients with signet ring cell (SRC) histology. Traditionally, SRC adenocarcinoma has been defined by ≥50% of the tumor composed of SRC. We hypothesized that patients with SRC even <50% would show resistance to standard multimodality therapy with poorer long-term outcomes.

METHODS

Patients treated with trimodality therapy for adenocarcinoma from 2006 to 2018 were evaluated for SRC on pretreatment biopsy specimens. Available hematoxylin and eosin slides containing SRC tumors were re-reviewed by an esophageal pathologist to quantify the percent composition of SRC.

RESULTS

SRC histology was identified on at least 1 pathologic specimen in 106 of 819 (13%) patients. Rates of pathologic complete response (pCR) among usual-type and SRC tumors were 25% (177/713) and 10% (11/106), respectively (P = .006). The pretreatment SRC components did not independently affect the rate of pCR (1%-10% SRC: 4% [2/46] pCR; 11%-49% SRC: 25% [7/28] pCR; 50%-100% SRC: 7% [2/30] pCR). Kaplan-Meier analysis demonstrated worse survival among patients with any degree of SRC present on pretreatment biopsy, as compared with usual-type esophageal adenocarcinoma (P < .0001). Cox multivariable analysis failed to identify a relationship between increasing SRC component and poorer survival.

CONCLUSIONS

We present the only known evaluation of the percentage of SRC component in esophageal carcinoma. Our data support the hypothesis that esophageal adenocarcinoma with any component of SRC are more resistant to chemoradiation with poorer survival. Pathologic reporting of esophageal adenocarcinoma should include any component of SRC. Alternative therapies in patients with any SRC component may be indicated.

Modified En Bloc Esophagectomy Compared With Standard Resection After Neoadjuvant Chemoradiation

BACKGROUND

Surgeons have shifted away from the practice of en bloc esophagectomy, particularly in the era of neoadjuvant therapies. Although some still advocate for this radical approach, contemporary data establishing its superiority are sparse. We hypothesized that a more complete, radical resection could be completed in the setting of chemoradiation without adding morbidity.

METHODS

Patients undergoing esophagectomy after neoadjuvant chemoradiation for esophageal adenocarcinoma from 2006-2018 were evaluated. Outcomes after right transthoracic en bloc esophagectomy were compared with standard esophagectomy to determine the impact on outcomes. A Cox proportional hazard model was evaluated, and logistic regression was performed to determine the impact of en bloc resection on postoperative morbidity.

RESULTS

A total of 604 patients were identified, including 133 (22%) who underwent modified en bloc esophagectomy. Positive margins were most likely to occur in standard esophagectomy (35 of 471, 7%) vs en bloc (3 of 133, 2%) (P = .026). En bloc resection yielded a greater lymph node harvest (27; interquartile range, 22-36), as compared to standard esophagectomy (22; interquartile range, 17-28), P < .001. Multivariable analysis demonstrated prolonged progression-free survival with en bloc resection (hazard ratio, 0.74; P = .041), with 3-year freedom from locoregional recurrences of 78% and 90% for standard and en bloc approaches (P = .044). There were no differences in cardiopulmonary, gastrointestinal, or wound complications, as well as leak or chylothorax.

CONCLUSIONS

Our experience demonstrates improved locoregional disease control with en bloc esophagectomy, with equivalent morbidity. Although these results may be multifactorial, including adequate clearance of both primary tumor and nodal micrometastases, this approach is safe and feasible.

Total Lesion Glycolysis Assessment Identifies a Patient Fraction With a High Cure Rate Among Esophageal Adenocarcinoma Patients Treated With Definitive Chemoradiation

OBJECTIVE

We aimed to determine whether tumor metabolism could be prognostic of cure in L-EAC patients who receive definitive chemoradiation.

SUMMARY BACKGROUND DATA

Patients with inoperable localized esophageal adenocarcinoma (L-EAC) often receive definitive chemoradiation; however, biomarkers and/or imaging variables to prognosticate cure are missing.

METHODS

Two hundred sixty-six patients with L-EAC who had chemoradiation but not surgery were analyzed from the prospectively maintained EAC databases in the Department of Gastrointestinal Medical Oncology at The University of Texas MD Anderson Cancer Center (Texas, USA) between March 2002 and April 2015. Maximum standardized uptake value (SUVmax) and total lesion glycolysis (TLG) from the positron emission tomography data were evaluated.

RESULTS

Of 266 patients, 253 (95%) were men; the median age was 67 years (range 20-91 yrs) and 153 had poorly differentiated L-EAC. The median SUVmax was 10.3 (range 0-87) and the median TLG was 85.7 (range 0-3227). Both SUVmax and TLG were higher among those with: tumors >5 cm in length, high clinical stage, and high tumor and node categories by TNM staging (all P < 0.0001). Of 234 patients evaluable for cure, 60 (25.6%) achieved cure. In the multivariable logistic regression model, low TLG (but not low SUVmax) was associated with cure (continuous TLG value: odds ratio 0.70, 95% confidence interval (CI) 0.54-0.92). TLG was quantified into 4 quartile categorical variables; first quartile (Q1; <32), second quartile (Q2; 32.0-85.6), third quartile (Q3; 85.6-228.4), and fourth quartile (Q4; >228.4); the cure rate was only 10.3% in Q4 and 5.1% in Q3 but increased to 28.8% in Q2, and 58.6% in Q1. The cross-validation resulted in an average accuracy of prediction score of 0.81 (95% CI, 0.75-0.86).

CONCLUSIONS

In this cross-validated model, 59% of patients in the 1st quartile were cured following definitive chemoradiation. Baseline TLG could be pursued as one of the tools for esophageal preservation.

Consensus molecular subtype (CMS) as a novel integral biomarker in colorectal cancer: A phase II trial of bintrafusp alfa in CMS4 metastatic CRC

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Background: Consensus Molecular Subtype 4 (CMS4) colorectal cancer (CRC) features increased TGFβ signaling, which may account for de novo resistance to immunotherapy for patients (pts) with microsatellite stable mCRC. To date, no prior trial has incorporated CMS status as an integral biomarker. Bintrafusp alfa (M7824) is a dual PD-L1 antibody/TGFβ trap with acceptable safety. Methods: Primary tumors from pts with metastatic CRC underwent CMS testing in a CLIA setting. In this Simon two-stage phase II trial (Ho: p < .05; Ha: p≥.25) for CMS4 mCRC, pts received bintrafusp alfa 1200mg IV every 14 days. RT (8Gy/day x 3 days) to a single metastatic lesion with abscopal intent was administered between doses 2 and 3. The primary objective was to estimate response rate (RR) per iRECIST. Correlative studies including RNA sequencing were performed on pre- and on-treatment biopsies. Results: 53 of 137 tested pts (39%) between June 2018-December 2019 had CMS4 mCRC. 13 of 15 treated pts received the agent with RT. All pts were evaluable for toxicity, and 13 for response. Median number of doses was 3 (IQR, 2-4). There was one grade 3 immune-related adverse event (colitis) requiring study discontinuation. There were 2 pts with stable disease and 11 with progressive disease as best response (RR 0%, 95% CI 0-22%). Enrollment was stopped after first stage for futility. Median PFS and OS were 1.6 months and 5.0 months, respectively. In paired samples, treatment with bintrafusp alfa resulted in an increase in the expression of IFNγ signature in nonirradiated metastatic lesions ( p< .001, q< .001). Updated results will be presented. Conclusions: This is the first reported clinical trial to utilize CMS status as an integral biomarker for pts with metastatic CRC and capitalizes on treating CRC subpopulations with targeted agents based upon validated RNA-based signatures. Although the efficacy for bintrafusp alfa and RT is low, changes in IFNγ signature provides a potential signal for refining therapeutic strategies based upon TGFβ enrichment in pts with mCRC. Clinical trial information: NCT03436563 .

Abstract IA27: Context-dependent role of KRAS in GI malignancies

Oncogenic Kras (Kras*) plays a key role in tumor maintenance and therapeutic resistance in several cancer types, although the precise biologic functions and mechanisms are not completely understood. We had previously shown in pancreatic ductal adenocarcinoma that some tumors underwent spontaneous relapse and were devoid of Kras* expression and downstream canonical MAPK signaling, instead acquiring amplification and overexpression of the transcriptional coactivator Yap1. Functional studies established the role of Yap1 and the transcriptional factor Tead2 in driving Kras*-independent tumor maintenance. In a second previous study, we developed a faithful colorectal cancer (CRC) mouse model and showed that Kras* drove invasion and maintenance in CRC. Here, utilizing this CRC mouse model, we demonstrate that KRAS* promotes a pronounced immune-suppressive profile distinguished by a predominance of myeloid-derived suppressor cells (MDSCs). We performed integrated transcriptomic and genomic analyses that identified IRF2 (Interferon Regulatory Factor 2) as a key KRAS* effector mediating immune suppression. IRF2 suppresses MDSC migration and infiltration in KRAS*-expressing CRC tumors by targeting the CXCL3/CXCR2 axis. We also observed that de novo resistance of KRAS*-expressing tumors to anti-PD1 therapy could be overcome by enforced IRF2 expression or by treatment with SX-682, a small-molecule CXCR2 antagonist. In addition, CRC patient tumors with higher IRF2 expression showed increased response to anti-PD1 therapy. This KRAS*-mediated immune-suppressive mechanism provides a framework for CRC patient selection and combination therapies to enhance the effectiveness of immune checkpoint blockade therapy in advanced disease.

Citation Format: Wen-Ting Liao, Michael J. Overman, Adam Boutin, Prasenjit Dey, Di Zhao, Guocan Wang, Jiexi Li, Zhengdao Lan, Jun Li, Xiaoying Shang, Ming Tang, Shan Jiang, Xingdi Ma, Peiwen Chen, Riham Katkhuda, Krittiya Korphaisarn, Deepavali Chakravarti, Qing Chang, Jianhua Zhang, Dipen M. Maru, Dean Y. Maeda, John A. Zebala, Scott Kopetz, Y. Alan Wang, Ronald A. DePinho. Context-dependent role of KRAS in GI malignancies [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr IA27.

Morbidity following salvage esophagectomy for squamous cell carcinoma: the MD Anderson experience

The survival advantage associated with the addition of surgical therapy in esophageal squamous cell carcinoma (ESCC) patients who demonstrate a complete clinical response to chemoradiotherapy is unclear, and many institutions have adopted an organ-preserving strategy of selective surgery in this population. We sought to characterize our institutional experience of salvage esophagectomy (for failure of definitive bimodality therapy) and planned esophagectomy (as a component of trimodality therapy) by retrospectively analyzing patients with ESCC of the thoracic esophagus and GEJ who underwent esophagectomy following chemoradiotherapy between 2004 and 2016. Of 76 patients who met inclusion criteria, 46.1% (35) underwent salvage esophagectomy. Major postoperative complications (major cardiovascular and pulmonary events, anastomotic leak [grade ≥ 2], and 90-day mortality) were frequent and occurred in 52.6% of the cohort (planned resection: 36.6% [15/41]; salvage esophagectomy: 71.4% [25/35]). Observed rates of 30- and 90-day mortality for the entire cohort were 7.9% (planned: 7.3% [3/41]; salvage: 8.6% [3/35]) and 13.2% (planned: 9.8% [4/41]; salvage: 17.1% [6/35]), respectively. In summary, esophagectomy following chemoradiotherapy for ESCC at our institution has been associated with frequent postoperative morbidity and considerable rates of mortality in both planned and salvage settings. Although a selective approach to surgery may permit organ preservation in many patients with ESCC, these results highlight that salvage esophagectomy for failure of definitive-intent treatment of ESCC may also constitute a difficult clinical undertaking in some cases.

A phase II trial of atezolizumab and bevacizumab in patients with advanced, progressive neuroendocrine tumors (NETs)

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Background: Neuroendocrine tumors (NETs) are relatively rare and heterogeneous tumors arising throughout the aerodigestive tract, which are incurable and life-limiting when metastatic. Prior studies of checkpoint inhibitors in NET patients have yielded minimal evidence of efficacy. Historically, effective therapies for advanced, progressive NET yield response rates less than 10% and progression-free survival (PFS) durations of approximately 11 months, as compared to approximately 4.5 months with placebo. Methods: We undertook a phase II basket study of atezolizumab in combination with bevacizumab in patients with rare cancers, and present here the data from the pancreatic NET (pNET) cohort and extrapancreatic NET (epNET) cohort, each of which included 20 patients with grade 1-2 NET that was progressive under any prior therapy. Patients received 1200mg of atezolizumab and 15mg/kg of bevacizumab IV q 21 days. The primary endpoint was confirmed objective response by RECIST 1.1. Results: The confirmed objective response rate with this combination was 20% (95% CI 6-44%) in the pNET cohort and 15% (95% CI 3-38%) in the epNET cohort. The median PFS in the pNET cohort is 19.6 months (95% CI 10.6-NR), while it was 14.9 months (95% CI 6.1-NR) in the epNET cohort, 1-year PFS was 75% and 52%, respectively. The combination was well-tolerated in this patient population, with the most common related treatment-emergent adverse events being hypertension (47.5%), proteinuria (37.5%), and fatigue (35%). The most common related grade 3/4 adverse events were hypertension (20%) and proteinuria (7.5%). Conclusions: The combination of atezolizumab and bevacizumab demonstrated moderate clinical activity in patients with advanced NETs. As pre-treatment and on-treatment biopsies were obtained for all patients, correlations with immune infiltration, mutations, and transcriptome alterations should provide additional insight into the mechanisms of response and resistance. Clinical trial information: NCT03074513.

ARID1A mutation to define an immunologically active subgroup in patients with microsatellite-stable colorectal cancer

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Background: AT-rich interactive domain 1A (ARID1A) is a chromatin regulator mutated in human cancers, frequently resulting in truncation and loss of expression of this protein. ARID1A recruits MSH2 during DNA replication to perform mismatch-repair. ARID1A deficiency has been shown to increase mutational load and immune activation in preclinical models (Shen J, Nat Med 2018) but its role in colorectal cancer (CRC) patients (pts) is being explored. Methods: The DNA sequencing and gene expression profiling of microsatellite-stable (MSS) CRC pts were extracted from TCGA and MD Anderson Cancer Center databases. The expression levels were normalized according to the mean values of each dataset. The mutational burden and expression signatures for IFN-γ and various immune markers were compared according to the ARID1A mutational status. Results: Among 417 pts with MSS CRC, 28 pts (6.7%) had a non-silent mutation in ARID1A. Out of the 58 genes most commonly mutated in CRC, non-silent mutation in ARID1A had the strongest association with the frame-shift mutation rate in MSS cases (8-fold increase, p< .001). ARID1A mutation had also a strong correlation with the IFN-γ expression signature in MSS CRC (Δz score +1.91, p< .001) . Compared with ARID1A wild-type pts, higher expression signatures for cytotoxic T cell function, NK cells, and immune checkpoints were observed in MSS ARID1A mutated cases. ARID1A mutant cases showed higher expressions of various immune checkpoint genes (CD274, CTLA4, HAVCR2, IDO1, LAG3, PDCD1, and PDCD1LG2) compared to wild-type cases (all p < .05). All findings were observed independently in both datasets. Conclusions: In MSS CRC, ARID1A mutation is associated with a high expression of IFN-γ pathway and immune signatures (such as cytotoxic T cell function and immune checkpoint markers). The immunogenicity of ARID1A mutant cases is likely due to the increased level of neoantigens resulting from the increased rate of frame-shift mutations. Tumors with ARID1A mutation may be more susceptible to immune therapy-based treatment strategies and should likely be recognized as a unique molecular subgroup in future immune therapy trials.

Taxane-based or platinum-based combination chemotherapy given concurrently with radiation followed by surgery resulting in high cure rates in esophageal cancer patients

BACKGROUND

Preoperative chemoradiotherapy (CRT) is one standard option for localized esophageal or gastroesophageal junction (GEJ) cancer patients but an optimal concurrent chemotherapy combination is not established.

METHODS

412 patients with resectable (cT1N1M0 or cT2-4N0-3M0) esophageal or GEJ cancer treated at the MDACC between October 2002 and June 2016 were analyzed. Exposures: CRT with DF or FOX followed by surgery (trimodality; TMT). Main outcomes and measures: Primary endpoints were overall survival (OS) and disease-free survival (DFS). Univariate and multivariate Cox analyses were performed.

RESULTS

Of the 412 patients analyzed, 264 (64%) received DF and 148 (36%) FOX. The median age was 60 years, and 95% had adenocarcinoma. The clinical complete response, positron-emission tomography response, and pathologic complete response rates were 73%, 73%, and 30%, respectively. Median follow-up was 60.4 months. Median OS for the entire cohort was 81.6 months (95% confidence interval [CI], 56.3-122.0); 81.6 months (95% CI, 55.9-not estimable) for the DF group and 67.7 months (95% CI, 41.6-not estimable) for the FOX group (P = .24). The median DFS was 45.6 months (95% CI, 33.1-61.7) for the entire cohort; 49.5 months (95% CI, 38.6-70.3) for DF and 33.0 months (95% CI, 18.1-70.4; P = .38) for FOX. Higher tumor location (unfavorable) and clinical complete response (favorable) were prognostic for both OS and DFS in the multivariate analysis.

CONCLUSION

At our high-volume center, the outcome of 412 TMT esophageal cancer patients was excellent. Taxane-based chemotherapy produces nonsignificant favorable trend.

Immunotherapy response evaluation with magnetic resonance elastography (MRE) in advanced HCC

Background

Currently, there are no imaging predictors of immunotherapy outcome in hepatocellular carcinoma (HCC). The study aim was to determine if stiffness changes measured by magnetic resonance elastography (MRE) can be a predictor of immunotherapy response in patients with advanced HCC.

Materials and methods

This was a prospective study of 15 patients with biopsy proven-advanced HCC treated with Pembrolizumab. All patients had liver MRE and liver biopsy at baseline and at 6 weeks of therapy. Change in HCC stiffness on MRE was compared with overall survival (OS), time to disease progression (TTP), and number of intratumoral CD3+ T lymphocytes. Analysis was performed using descriptive statistics and Spearman correlation (R); p-value < 0.05 was considered statistically significant.

Results

Nine patients were evaluable. Median age was 71 years (range, 54–78). Etiology of liver disease was HCV (n = 4), HBV (n = 1) and NASH (n = 4). Median OS and TTP were 44 weeks and 13 weeks, respectively. Average baseline HCC stiffness and change in HCC stiffness were 5.0 kPa and 0.12 kPa, respectively. In contrast, average non-tumor liver stiffness was 3.2 kPa, and did not significantly change at 6 weeks (p = 0.42). Average size of measured tumor and change in size were 4 cm and − 0.32 cm, respectively. Change in HCC stiffness at 6 weeks correlated significantly with OS (R = 0.81), and TTP (R = 0.88,p < 0.01). Abundance of intratumoral T lymphocytes on tumor biopsy correlated significantly with HCC stiffness (R = 0.79,p = 0.007).

Conclusion

Our pilot MRE data suggests early change in tumor stiffness may be an indicator of immunotherapy response in patients with advanced HCC.

Targeting CDK9 and MCL-1 by a new CDK9/p-TEFb inhibitor with and without 5-fluorouracil in esophageal adenocarcinoma

Background:

CDK9 inhibitors are antitumorigenic against solid tumors, including esophageal adenocarcinoma (EAC). However, efficacy of a CDK9 inhibitor combined with 5-fluorouracil (5-FU) and target proteins that are targeted by these agents in EAC are unknown.

Methods:

The anti-EAC efficacy of a new CDK9 inhibitor, BAY1143572, with and without 5-FU was assessed in vitro and in xenograft models in athymic nu/nu mice. Synergy between BAY1143572 and 5-FU in inhibiting cell proliferation was analyzed by calculating the combination index using CompuSyn software. Potential targets of BAY1143572 and 5-FU were identified by reverse-phase protein array. The effects of BAY1143572 and 5-FU on MCL-1 in vitro were analyzed by Western blotting, quantitative real-time polymerase chain reaction, and chromatin immunoprecipitation assay. MCL-1 protein expression in tumors from patients with locoregional EAC treated with chemoradiation and surgery was assessed by immunohistochemistry.

Results:

BAY1143572 had dose-dependent antiproliferative and proapoptotic effects and demonstrated synergy with 5-FU against EAC in vitro. The median volumes of FLO-1 and ESO-26 xenografts treated with 5-FU plus BAY114352 were significantly smaller than those of xenografts treated with either agent alone (p < 0.05). BAY1143572 downregulated MCL-1 by inhibiting HIF-1α binding to the MCL-1 promoter. 5-FU enhanced BAY1143572-induced MCL-1 downregulation and stable MCL-1 overexpression reduced the apoptosis induced by BAY1143572 and 5-FU in vitro. High patients’ tumor MCL-1 expression was correlated with shorter overall and recurrence-free survival.

Conclusions:

BAY1143572 and 5-FU have synergistic antitumorigenic effects against EAC. MCL-1 is a downstream target of CDK9 inhibitors and a predictor of response to neoadjuvant chemoradiation in EAC.

Abstract 3859: Targeting CDK9 and MCL-1 by a New CDK9/p-TEFB Inhibitor with and without 5-fluorouracil in esophageal adenocarcinoma

Background: CDK9 inhibitors are anti-tumorigenic against several solid tumors including esophageal adenocarcinoma (EAC). However, efficacy of CDK9 inhibitor as adjuvant to chemotherapy and target proteins shared between these two drugs are not known.

Methods: Efficacy of a new CDK9 inhibitor, BAY1143572 with and without 5-fluorouracil (5-FU) on tumor growth was tested in vitro and xenograft models of EAC. We tested effects of these agents on MCL-1 in vitro. We also analyzed a possible role of MCL-1 as a predictor of survival in patients with EAC.

Results: BAY1143572 had a dose-dependent anti-proliferative and pro-apoptotic effects in vitro. BAY1143572 and 5-FU had strong synergy in vitro. Median tumor volume of FLO1 or ESO26 xenografts in cohort treated with combination of two drugs was 82% or 55% smaller than the cohort treated with 5-FU alone, and 46 % or 33% smaller than the cohort treated with BAY114352 alone (p&lt;0.05). BAY1143572 transcriptionally downregulated MCL-1 by inhibiting HIF-1α binding to the MCL-1 promoter. 5-FU enhanced BAY1143572 induced MCL-1 downregulation in vitro. Stable overexpression of MCL-1 reduced apoptosis by BAY1143572 and 5-FU. Higher tumor cell MCL-1 expression correlated with shorter overall survival in patients with EAC treated with chemoradiation and surgery.

Conclusion: CDK9 inhibitor and 5-FU are synergistic and MCL-1 is a target of CDK9 inhibitor in EAC.

Citation Format: zhimin Tong, Alicia Mejia, Omkara Veeranki, Anuj Verma, Arlene Correa, Viren Patel, Rashmi Dokey, Luisa Solis, Barbara Mino, Riham Kathkuda, Jaime Canales, Steven Lin, Sunil Krishnan, Scott Kopetz, Mariela Blum, Jaffer Ajani, Wayne Hofstetter, Dipen M Maru. Targeting CDK9 and MCL-1 by a New CDK9/p-TEFB Inhibitor with and without 5-fluorouracil in esophageal adenocarcinoma [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 3859.

Association of TGF-β expression with intratumoral infiltration of cytotoxic T lymphocytes in patients with microsatellite-stable colorectal cancer

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Background: Transforming growth factor- β pathway (TGF-β) has an established role in promoting growth, invasion, metastasis as well as epithelial to mesenchymal (EMT) transition. Among 4 different described molecular subtypes of colorectal cancer (CRC), consensus molecular subtype 4 (CMS4) comprises up to 25% of CRC pts, distinguished by activation of this pathway, and is associated with higher relapse rate and poor prognosis. Recently, it has also been proposed that TGF-β activation drives immune evasion in murine models, but these findings have not been clinically validated. Methods: Using multi-gene RNA expression profiling, fresh-frozen paraffin-embedded samples of 35 patients with CRC were analyzed to determine TGF-β and EMT expression levels. Multiplexed IHC staining was performed on FFPE tumor blocks by using the Opal 7-Color fIHC Kit and the stained slides were scanned by a Vectra multispectral microscope (PerkinElmer) to measure infiltration of immune cells (i.e., T lymphocytes, cytotoxic T lymphocytes (CTL), T cell antigen-experienced, macrophages, etc.) in the tumor, stroma, and both components. TGF-β and EMT expression levels – as continuous variables - were compared with the infiltration of various immune cells using Spearman’s rank correlation analysis. Results: Among 35 pts, 28 pts had non-CMS1/MSS CRC. TGF-β RNA expression in the tumor microenvironment of these samples was inversely associated with the infiltration of CTL into the tumor (r=-0.43, p= 0.022). In contrast, there was no association of TGF-β with non-cytotoxic T-cells or macrophage infiltration. The tumor and stromal CTL infiltration differed substantially by CMS ( p=0.04, p=0.02, respectively) with tumor infiltration lowest in CMS4 (n=7). Consistent with this, EMT gene signature, which includes TGF-β expression, showed a similar inverse correlation with CTL infiltration (r=-0.48, p=0.009). Conclusions: TGF-β and EMT gene signatures have important roles in the exclusion of CTL in the tumor microenvironment of CRC pts. Inhibiting TGF-β pathway can potentially increase the intratumoral infiltration of CTL, which is a necessary (but not sufficient) step for immunotherapy response in MSS CRC. Clinical trials evaluating this hypothesis are currently ongoing (NCT03436563).

Association of PIK3CA mutations (mut) with immune engagement and clinical benefit from immunotherapy in microsatellite stable (MSS) colorectal cancer (CRC) patients (pts)

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Background: PI3K pathway alterations, PIK3CA mut or PTEN loss, are known to modulate anti-tumor immune microenvironment. MSS CRC pts respond infrequently to immunotherapy, suggesting the presence of a rare MSS immunogenic subset. We investigated the immune repertoire and outcomes on immunotherapy trials in PIK3CA mut MSS CRC pts. Methods: Immune infiltrates and checkpoints were evaluated using quantitative immuno-histochemistry (IHC) on primary CRC. Mutations were assessed by next generation sequencing. PIK3CA mut neoepitopes and HLA allele affinities were predicted using NetMHC 4.0 Server. Outcomes of MSS CRC pts enrolled in 7 immunotherapy trials were assessed. Clinical benefit (CB) was defined as CR, PR or SD of 24 weeks. Time to progression (TTP) was calculated using Kaplan-Meier Method. PIK3CA mut vs wild type (wt) groups were compared using Mann-Whitney U, Fisher’s exact, or Log-Rank tests as appropriate. Results: PI3K alterations were present in 14/40 MSS CRC pts in IHC cohort (7 PIK3CA mut, 33 wt; 7 PTEN loss, 33 intact). The center of PIK3CA mut MSS CRC had higher median densities of CD3+ cells [1112 (IQ range 865-1421) vs 435 (300-744) cells/mm3; P=0.037] and CD8+ cells [554 (331-1200) vs 185 (60-473) cells/mm3; P=0.037] as compared to PIK3CA wt tumors. Intratumoral immune infiltrates did not differ by PTEN IHC staining in MSS CRC. PD-L1 H-scores were also higher in PIK3CA mut MSS CRC [85 (34-114) vs 29 (11-60); P=0.01]. Several activating PIK3CA mut (E542K, E545K, H1047R) were predicted to generate true neoepitopes with high binding affinity to common HLA types. Indeed, among MSS CRC pts enrolled in 7 immunotherapy trials, half (4/8) of PIK3CA mut pts derived CB as compared to 3/35 (8.6%) PIK3CA wt pts (P=0.015). PIK3CA mut pts had trend towards longer TTP (3.8 months in mut vs 2.1 months in wt; P=0.08). CB or TTP did not differ by colon sidedness, monotherapy / combination therapy, number of mut, or mut in other key genes ( APC, SMAD4, TP53, KRAS, NRAS or BRAF). Conclusions: PIK3CA mut MSS CRC are associated with increased cytotoxic T cell infiltration, higher PD-L1 expression, and greater clinical benefit from immunotherapy. Further investigation of immunotherapy outcomes in the context of neoepitope-HLA allele interaction may help identify a subset of PIK3CA mut MSS CRC pts who are likely to benefit from immunotherapy.

Paratracheal lymph node metastasis in operable localized esophageal and gastroesophageal junction adenocarcinoma

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Background: Paratracheal lymph node (LN) is considered regional for esophageal cancer, but its metastatic rate and influence to survival remain unclear. We aimed to evaluate the frequency of paratracheal LN metastasis and its prognostic influence. Methods: 1199 patients with localized esophageal or gastroesophageal junction adenocarcinoma (EAC) (January 2002 and December 2016) in our Gastrointestinal Medical Oncology Database were analyzed. 1R, 1L, 2R, 2L, 4R, and 4L according to 8th AJCC classification were defined as paratracheal LN. Results: Of 1199 patients, 73 (6.1%) had positive parataracheal LN at diagnosis. The median overall survival (OS) in 73 patients with initial paratracheal LN involvement was 2.10 years (range, xx). Of 1071 patients who were eligible for recurrence evaluation, 70 patients (6.5%) developed positive paratracheal LN recurrences as first recurrence. The median time to recurrence was 1.28 years (range; 0.28-5.96 years) and the median OS after recurrence was 0.95 years (range; 0.03-7.89). OS in 35 patients who had only patatracheal LN recurrence was significantly longer than in patients who had with other distant recurrences (median 2.26 vs 0.51 years; p < 0.0001). Higher T stage (T3/T4) was an independently risk factor for paratracheal LN recurrence (OR 5.10, 95% CI 1.46-17.89). We segregated patients in 3 groups based on the distance from esophagogastric junction to tumor proximal edge (lower; ≤2cm, middle; 2.0-7.0cm, higher; > 7.0cm), positive paratrachal LN metastases were more frequent in the proximal tumors (lower 4.2%, middle 12.0%, higher 30.3%; Cochran-Armitage Trend test, p < 0.001). Conclusions: Paratracheal LN metastases were associated with shorter survival in localized EAC patients. Careful investigation and surveillance for paratracheal LN are warranted.

KRAS-IRF2 Axis Drives Immune Suppression and Immune Therapy Resistance in Colorectal Cancer

The biological functions and mechanisms of oncogenic KRAS^G12D (KRAS^∗) in resistance to immune checkpoint blockade (ICB) therapy are not fully understood. We demonstrate that KRAS^∗ represses the expression of interferon regulatory factor 2 (IRF2), which in turn directly represses CXCL3 expression. KRAS^∗-mediated repression of IRF2 results in high expression of CXCL3, which binds to CXCR2 on myeloid-derived suppressor cells and promotes their migration to the tumor microenvironment. Anti-PD-1 resistance of KRAS^∗-expressing tumors can be overcome by enforced IRF2 expression or by inhibition of CXCR2. Colorectal cancer (CRC) showing higher IRF2 expression exhibited increased responsiveness to anti-PD-1 therapy. The KRAS^∗-IRF2-CXCL3-CXCR2 axis provides a framework for patient selection and combination therapies to enhance the effectiveness of ICB therapy in CRC.

Comparison of early radiological predictors of outcome in patients with colorectal cancer with unresectable hepatic metastases treated with bevacizumab

OBJECTIVE

The purpose was to validate the prognostic value of an early optimal morphological response on CT in patients treated with bevacizumab-containing chemotherapy for unresectable colorectal cancer liver metastases (CLM). It also evaluated the prognostic value of size-based criteria and the association of optimal morphological response with the receipt of bevacizumab.

DESIGN

141 patients treated first using bevacizumab and 142 patients from a randomised study evaluating the addition of bevacizumab to oxaliplatin-based chemotherapy were retrospectively analysed. Radiologists evaluated pretreatment and restaging CT scans using morphological response criteria. Responses were also assessed with size-based criteria: Response Evaluation Criteria in Solid Tumors (RECIST), early tumour shrinkage (ETS) and deepness of response (DpR). The ability of each criterion to predict progression-free survival (PFS), overall survival (OS) and postprogression survival (PPS) was determined using a univariate Cox proportional hazards model.

RESULTS

In both populations, median PFS was significantly longer for patients achieving an optimal morphological response (10.4 vs 6.8 months, p=0.03; and 8.3 vs 4.9 months, p<00001, respectively). Neither RECIST nor ETS responses were associated with a prolonged PFS. Median OS was longer for those with an optimal morphological response but only at second restaging in the first population (n=141, 20.8 vs 12.3 months, p=0.002). DpR but not optimal morphological response was associated with PPS. In the randomised study, an optimal morphological response was 6.2 times more likely among patients receiving bevacizumab (p<0.0001).

CONCLUSION

In patients with unresectable CLM, early morphological response may be a better predictor of PFS than size-based response. The addition of bevacizumab improves morphological response rate.

Barrett's Esophagus after Bimodality Therapy in Patients with Esophageal Adenocarcinoma

INTRODUCTION

Barrett's esophagus (BE) may be present in patients with esophageal adenocarcinoma (EAC) after bimodality therapy (BMT). There is no specific guidance for follow-up of these patients with regard to the presence of BE or dysplasia. In this study, we assessed the outcomes of patients who, after BMT, had BE and those who did not.

METHOD

Patients with EAC who had BMT were identified and analyzed retrospectively in two groups, with and without BE. We compared patient characteristics and outcome variables (local, distant, and no recurrence).

RESULTS

Of 228 patients with EAC, 68 (29.8%) had BE before BMT. Ninety-eight (42.9%) had BE after BMT, and endoscopic intervention was done in 11 (11.2%). With a median follow-up of 37 months, the presence of post-BMT BE was not significantly associated with overall survival (OS) and local recurrence-free survival (LRFS). Similarly, endoscopic intervention was not significantly associated with OS and LRFS. Fifty (73.5%) patients with BE before BMT had BE after BMT (p < 0.0001).

CONCLUSION

The presence of BE after BMT was not associated with increased risk of local recurrence. The local recurrence rate was not influenced by endoscopic intervention. Prospective studies are warranted to generate guidance for intervention, if necessary, for this group of EAC patients.

Actionable Locoregional Relapses after Therapy of Localized Esophageal Cancer: Insights from a Large Cohort

OBJECTIVE

The goal of surveillance after therapy of localized esophageal cancer (LEC) is to identify actionable relapses amenable to salvage; however, the current surveillance algorithms are not optimized. We report on a large cohort of LEC patients with actionable locoregional relapses (LRRs).

METHODS

Between 2000 and 2013, 127 (denominator = 752) patients with actionable LRR were identified. Histologic/cytologic confirmation was the gold standard. All surveillance tools (imaging, endoscopy, fine needle aspiration) were assessed.

RESULTS

Most patients were men (89%), had adenocarcinoma (79%), and had no new symptoms (72%) when diagnosed with LRR. In trimodality patients, endoscopic confirmation of positron emission tomography-computed tomography-suspected LRR occurred in only 44%, and 56% required additional tools (e.g., fine needle aspiration). Alternatively, in bimodality patients, endoscopy confirmed LRRs in 81%. Trimodality patients had a higher risk of subsequent LRR/distant metastases after the first LRR than the bimodality patients (p = 0.03). In all patients, 78% of the subsequent relapses were distant. For patients who were salvaged, survival was significantly prolonged (50.6 vs. 25.1 months, p < 0.01).

CONCLUSIONS

Patients live longer after successful salvage of the LRR than if salvage is not possible. After LRR, patients have a high risk of subsequent distant metastasis and whether the second relapse is local or distant, survival is uniformly poor.

Preoperative Nomogram to Risk Stratify Patients for the Benefit of Trimodality Therapy in Esophageal Adenocarcinoma

Purpose

To develop a nomogram that estimates 1-year recurrence-free survival (RFS) after trimodality therapy for esophageal adenocarcinoma and to assess the overall survival (OS) benefit of esophagectomy after chemoradiotherapy (CRT) on the basis of 1-year recurrence risk.

Methods

In total, 568 consecutive patients with potentially resectable esophageal adenocarcinoma who underwent CRT were included for analysis, including 373 patients who underwent esophagectomy after CRT (trimodality therapy), and 195 who did not undergo surgery (bimodality therapy). A nomogram for 1-year RFS was created using a Cox regression model. The upper tertile of the nomogram score was used to stratify patients in low-risk and high-risk groups for 1-year recurrence. The 5-year OS was compared between trimodality and bimodality therapy in low-risk and high-risk patients after propensity score matching, respectively.

Results

Median follow-up for the entire cohort was 62 months. The 5-year OS in the trimodality and bimodality treatment groups was 56.3% (95% confidence interval [CI] 47.9–64.7) and 36.9% (95% CI 31.4–42.4), respectively. The final nomogram for the prediction of 1-year RFS included male gender, poor histologic grade, signet ring cell adenocarcinoma, cN1, cN2-3, and baseline SUV_max, with accurate calibration and reasonable discrimination (C-statistic: 0.66). Trimodality therapy was associated with improved 5-year OS in low-risk patients (p = 0.003), whereas it showed no significant survival benefit in high-risk patients (p = 0.302).

Conclusions

The proposed nomogram estimates early recurrence risk. The addition of surgery to CRT provides a clear OS benefit in low-risk patients. The OS benefit of surgery in high-risk patients is less pronounced.

Electronic supplementary material

The online version of this article (10.1245/s10434-018-6435-4) contains supplementary material, which is available to authorized users.

Metabolic activity to predict clinical response and prognosis in esophageal adenocarcinoma patients treated with bimodality

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Background: Patients with localized esophageal adenocarcinoma (L-EAC) who are not suitable for surgery receive definitive chemoradiation. However, there are no biomarkers or imaging variables to predict clinical complete response (cCR; negative bx and physiologic PET post chemoradiation) or prognosticate favorable overall survival (OS). We analyzed tumor metabolic activity by standardized uptake value (SUV) or total lesion glycolysis (TLG). Methods: 266 patients with L-EAC, who declined or were unsuitable for surgery, were analyzed. Cox proportional hazards regression model for OS was analyzed using categorized SUV (low; < 6.5, moderate; 6.5-12.9, or high; ≥12.9) or TLG (low; < 24.2, moderate; 24.2-82.6, or high; ≥82.6). Logistic regression model for cCR was analyzed using categorized SUV (low; < 5.4 or high; ≥5.4) or TLG (low; < 27.0 or high; ≥27.0). Results: Mean SUV and TLG were 12.8 ± 10.7 and 209 ± 376.8, respectively. Both SUV and TLG were significantly associated with the length of the tumor (p < 0.0001) and clinical stage (p < 0.0001). Higher SUV and TLG were significantly associated with shorter OS than low SUV and TLG (moderate SUV; HR 1.79, CI 1.19-2.69, high SUV; HR 2.82, 1.90-4.18, moderate TLG; HR 1.82, 1.14-2.90, high TLG; 3.16, 2.11-4.74). 68 patients (28%) achieved cCR and remained free of recurrence. In the multivariate logistic regression model, low SUV and low TLG highly predicted cCR without recurrence (low SUV; OR 3.15, 1.38–7.19, low TLG; OR 4.79, 2.28-10.08). Conclusions: Tumor metabolic activity is highly associated with prognosis and response to chemoradiation in patients with L-EAC not undergoing surgery. Further refinements (addition of biomarkers) could allow personalized care of these patients.

Early Metabolic Change after Induction Chemotherapy Predicts Histologic Response and Prognosis in Patients with Esophageal Cancer: Secondary Analysis of a Randomized Trial

BACKGROUND

Early metabolic response after preoperative induction chemotherapy (IC) appears to predict histologic response and prognosis in esophageal cancer (EC), but the usefulness of this approach needs further development.

OBJECTIVE

We evaluated metabolic response after one cycle of IC using positron emission tomography (PET) to correlate PET response and outcomes.

PATIENTS AND METHODS

We retrospectively analyzed PET data from a randomized phase 2 trial (NCT00525915) of chemoradiation and surgery with or without IC for the treatment of EC. PET was performed at baseline, after one cycle of IC, and 5-7 weeks after chemoradiation. The relationship between PET response (≥35% reduction in standardized uptake value [SUV]) after IC and treatment response was analyzed.

RESULTS

In 63 patients who received IC, the mean initial SUVmax prior to treatment was 11.9 ± 8.04 and mean SUVmax after one cycle of IC was 6.47 ± 4.45. The mean SUV reduction after IC was 39.3%. Eleven of 37 PET responders achieved a pathologic complete response (pCR), but only two of 22 PET non-responders did (univariate logistic regression; odds ratio: 4.25, 95% confidence interval: 0.83-21.77; p = 0.08). PET responders to IC had significantly longer overall survival (OS) than PET nonresponders (log-rank p = 0.009). PET response after chemoradiation was not correlated with OS (log-rank p = 0.15).

CONCLUSION

Early PET response after IC is prognostic, but subsequent PET changes (for example, after chemoradiation) are not prognostic. Early PET response might have the potential of predicting pCR.

The rate of novel actionable mutations in standard of care NGS panel testing in gastrointestinal malignancies

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Background: In advanced gastrointestinal (GI) malignancies, genetic profiling is often performed with the goal of facilitating enrollment of patients into clinical trials. While multigene genetic profiling has become the standard of care in many practices, the data on success rate of identifying actionable genomic alterations remain limited. In this study, we aimed to characterize the rate of actionable mutations using larger ( > 150 genes) and smaller ( < 150 genes) panels across different GI malignancies. Methods: We reviewed all reports of formalin-fixed paraffin-embedded clinical specimens sent for next-generation sequencing (NGS-using assays of at least 45 genes) for patients with advanced GI malignancies between 2012-2017 at MD Anderson Cancer Center. Actionable mutations were defined as those matching or informing the use of targeted therapies available in clinical trials, or FDA-approved. These were determined by a precision oncology support team (pct.mdanderson.org), using available literature and functional genomic screens. Novel actionable mutations were defined as those not used in current testing guidelines for GI malignancies. Results: Out of 11968 detected mutations, 3832(32.0%) were deemed to be actionable mutations and the remainder were either in non-actionable genes, deemed benign, or variants of unknown significance. Therefore, 1987 (65.1%) of assays had actionable mutations. When limited to novel actionable mutations, the rate fell to 21.5% (659/3052). Compared to CRC, other GI malignancies were 1.65 times more likely to have a novel actionable mutation (95% CI 1.35-2.00, p< .001). The use of larger and smaller panels did not differ in detecting novel actionable mutations, but larger panels resulted in a 3.5-fold higher number of mutations not deemed clinically actionable. Conclusions: Despite incorporation of NGS in oncology practice for GI malignancies, the success rate of detecting novel actionable mutations beyond those in the current guidelines remains low. Using assays with larger gene numbers does not seem to improve this detection rate. Future studies are required to evaluate the success rate of clinical interventions when actionable alterations are present.

Association of phosphatidylinositol 3-kinase (PI3K) pathway activation with increased immune checkpoint expression in colorectal cancer (CRC) patients

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Background: PI3K pathway is a known modulator of anti-tumor immune response and is frequently activated in CRC through genetic alterations such as PTEN loss (PTENloss) and PIK3CA mutations (PIK3CAmut). This study aims to determine the impact of these alterations on immune cell infiltration, priming and activation in early stage CRC patients (pts). Methods: Immune infiltrates and checkpoints were evaluated using quantitative immunohistochemistry (IHC) on primary CRC (N = 59) for both center of tumor (CT) and invasive margin (IM). Pts were evaluated by presence or absence of either PTENloss or PIK3CAmut (collectively termed PI3K pathway alterations). Microsatellite unstable (MSI) and stable (MSS) tumors were analyzed separately. Clinicopathologic data was examined for potential associations with PI3K pathway alterations. Separately, mRNA data (Agilent) was obtained for immune related genes from an internal cohort with PTEN and PIK3CA annotation (N = 73). Results: 59 pts comprised IHC cohort (40 MSS, 19 MSI); 23 pts (39%) had PTENloss or PIK3CAmut. In Agilent cohort, 16 of 73 pts (22%) had PI3K pathway alterations. In MSS CRC, these alterations were more common in CMS1 (p = 0.03), on right side (p = 0.048) and with peritumoral lymphocytes (p = 0.031). MSS pts with PI3K pathway alterations had higher PD1 protein expression (p = 0.04), 2.1 and 2.3 times increased density of CD3+ (p = 0.01) and CD8+ (p = 0.04) cells respectively, and higher Granzyme B protein expression (p = 0.04) in the CT. These pts also had higher PDL1 gene expression (p = 0.046). MSS CRC pts with PIK3CAmut similarly had 2 times more PDL1 protein expression in epithelial cells of the IM (p = 0.01). Alternate checkpoints were also increased in pts with PI3K pathway alterations, including higher protein expression of LAG3 in CT (P = 0.046) and higher gene expression of CTLA4, TIM3, and TIGIT (P < 0.05 for all). Conclusions: PI3K pathway activated MSS CRC is associated with increased immune engagement, but also upregulation of key immune checkpoints in early stage tumors resulting in an ineffective immune response. Combination of PI3K pathway inhibition with immunotherapy merits investigation in this subset of pts.

Arginine methylation of EGFR: a new biomarker for predicting resistance to anti-EGFR treatment

Arginine methylation of the epidermal growth factor receptor (meEGFR) increases the binding affinity of EGFR ligands and is reported to have a role in predicting response to anti-EGFR agents. This study investigated the predictive impact of meEGFR in metastatic colorectal cancer (mCRC) patients treated with anti-EGFR agents. Two patient cohorts were evaluated. Cohort 1 consisted of mCRC patients with documented disease progression following anti-EGFR treatment. Circulating tumor cells (CTCs) were isolated and distinguished based on CD45^- and Epcam⁺. Cohort 2 consisted of formalin fixed paraffin-embedded (FFPE) blocks from a prospective cohort. meEGFR in both cohorts was identified by positive staining for me-R198/200 EGFR signal. CTCs were identified in 30 out of 47 cases in cohort 1. Of those 30, meEGFR-CTCs were identified in 19 cases. Mean total meEGFR-CTCs counts was 2.3 (range 0-30) cells per 7.5 ml. There was no association between meEGFR-CTCs and clinic-pathological-molecular features. In RAS^wt/BRAF^wt patients with high levels of meEGFR-CTCs ratio (≥ 0.23) had significantly inferior PFS with anti-EGFR treatment (HR = 3.4, 95% CI 1.5-7.9, P = 0.004). By contrast, high levels of meEGFR in the untreated tumor tissues had no correlation with anti-EGFR treatment duration in cohort 2. Therefore, meEGFR-CTCs may have the potential to serve as a "liquid biopsy" biomarker to predict anti-EGFR treatment efficacy.

Pathological complete response in patients with esophageal cancer after the trimodality approach: The association with baseline variables and survival-The University of Texas MD Anderson Cancer Center experience

BACKGROUND

Reports are limited regarding clinical and pretreatment features that might predict a pathological complete response (pathCR) after treatment in patients with esophageal cancer (EC). This might allow patient selection for different strategies. This study examines the association of a pathCR with pretreatment variables, overall survival (OS), recurrence-free survival (RFS), and patterns of recurrence in a large cohort from a single institution.

METHODS

The baseline clinical features of 911 consecutive patients with EC who were treated with trimodality therapy from January 2000 to November 2013 were analyzed. A pathCR was defined as a surgical specimen with no residual carcinoma (primary or nodes). Logistic regressions were used to identify independent baseline features associated with a pathCR. We applied log-rank testing and Cox models to determine the association between a pathCR and the time-to-event outcomes (OS and RFS).

RESULTS

Of 911 patients, 218 (23.9%) achieved a pathCR. The pathCR rate was 23.1% for adenocarcinoma and 32.2% for squamous cell carcinoma. A lower pathCR rate was observed for 1) older patients (>60 years), 2) patients with poorly differentiated tumors, 3) patients with signet ring cells (SRCs), and 4) patients with a higher T stage. Patients with a pathCR had longer OS and RFS than those without a pathCR (P = .0021 and P = .0011, respectively). Recurrences occurred more in non-pathCR patients. Distant metastases were the most common type of recurrence. PathCR patients developed brain metastases at a marginally higher rate than non-pathCR patients (P = .051).

CONCLUSIONS

In this large cohort study, a pathCR is confirmed to be associated with better OS and RFS. The presence of a poorly differentiated tumor or SRCs reduces the likelihood of a pathCR. Future research should focus on molecular classifiers. Cancer 2017;123:4106-4113. © 2017 American Cancer Society.