Analysis of Donor Pancreata Defines the Transcriptomic Signature and Microenvironment of Early Neoplastic Lesions.

The adult healthy human pancreas has been poorly studied given the lack of indication to obtain tissue from the pancreas in the absence of disease and rapid postmortem degradation. We obtained pancreata from brain dead donors, thus avoiding any warm ischemia time. The 30 donors were diverse in age and race and had no known pancreas disease. Histopathologic analysis of the samples revealed pancreatic intraepithelial neoplasia (PanIN) lesions in most individuals irrespective of age. Using a combination of multiplex IHC, single-cell RNA sequencing, and spatial transcriptomics, we provide the first-ever characterization of the unique microenvironment of the adult human pancreas and of sporadic PanIN lesions. We compared healthy pancreata to pancreatic cancer and peritumoral tissue and observed distinct transcriptomic signatures in fibroblasts and, to a lesser extent, macrophages. PanIN epithelial cells from healthy pancreata were remarkably transcriptionally similar to cancer cells, suggesting that neoplastic pathways are initiated early in tumorigenesis. SIGNIFICANCE: Precursor lesions to pancreatic cancer are poorly characterized. We analyzed donor pancreata and discovered that precursor lesions are detected at a much higher rate than the incidence of pancreatic cancer, setting the stage for efforts to elucidate the microenvironmental and cell-intrinsic factors that restrain or, conversely, promote malignant progression. See related commentary by Hoffman and Dougan, p. 1288. This article is highlighted in the In This Issue feature, p. 1275.

Characteristics of Mismatch Repair-Deficient Colon Cancer in Relation to Mismatch Repair Protein Loss, Hypermethylation Silencing, and Constitutional and Biallelic Somatic Mismatch Repair Gene Pathogenic Variants.

BACKGROUND: Mismatch repair-deficient colon cancer is heterogeneous. Differentiating inherited constitutional variants from somatic genetic alterations and gene silencing is important for surveillance and genetic counseling. OBJECTIVE: This study aimed to determine the extent to which the underlying mechanism of loss of mismatch repair influences molecular and clinicopathologic features of microsatellite instability-high colon cancer. DESIGN: This is a retrospective analysis. SETTINGS: This study was conducted at a comprehensive cancer center. PATIENTS: Patients with microsatellite instability-high colon cancer of stage I, II, or III were included. INTERVENTION: Patients underwent a curative surgical resection. MAIN OUTCOME MEASURES: The main outcome measures were hypermethylation of the MLH1 promoter, biallelic inactivation, constitutional pathogenic variants, and loss of specific mismatch repair proteins. RESULTS: Of the 157 identified tumors with complete genetic analysis, 66% had hypermethylation of the MLH1 promoter, 18% had constitutional pathogenic variants, (Lynch syndrome), 11% had biallelic somatic mismatch repair gene pathogenic variants, and 6% had unexplained high microsatellite instability. The distribution of mismatch repair loss was as follows: MLH1 and PMS2 co-loss, 79% of the tumors; MSH2 and MSH6 co-loss, 10%; MSH6 alone, 3%; PMS2 alone, 2%; other combinations, 2%; no loss, 2%. Tumor mutational burden was lowest in MLH1- and PMS2-deficient tumors. MSH6-deficient tumors had the lowest levels of tumor-infiltrating lymphocytes, lowest MSI scores, and fewest frameshift deletions. Patients with MLH1 promoter hypermethylation were significantly more likely to be older and female and to have right-sided colon lesions than patients with biallelic inactivation. Mutation was the most prevalent second hit in tumors with biallelic inactivation and tumors of patients with Lynch syndrome. LIMITATIONS: This study was limited by potential selection or referral bias, missing data for some patients, and relatively small sizes of some subgroups. CONCLUSIONS: Clinical characteristics of mismatch repair-deficient colon cancer vary with the etiology of microsatellite instability, and its molecular characteristics vary with the affected mismatch repair protein. See Video Abstract at http://links.lww.com/DCR/B984 . CARACTERSTICAS DEL CNCER DE COLON CON DEFICIENCIA EN LA REPARACIN DE ERRORES DE EMPAREJAMIENTO EN RELACIN CON LA PRDIDA DE PROTENAS MMR, SILENCIAMIENTO DE LA HIPERMETILACIN Y LAS VARIANTES PATGENAS SOMTICAS DE GENES MMR CONSTITUCIONAL Y BIALLICO: ANTECEDENTES:El cáncer de colon deficiente en la reparación de errores de emparejamiento es heterogéneo. La diferenciación de las variantes constitucionales heredadas de las alteraciones genéticas somáticas y el silenciamiento de genes es importante para la vigilancia y el asesoramiento genético.OBJETIVO:Determinar hasta qué punto el mecanismo subyacente de pérdida de reparación de desajustes influye en las características moleculares y clinicopatológicas del cáncer de colon con alta inestabilidad de microsatélites.DISEÑO:Análisis retrospectivo.ESCENARIO:Centro integral de cáncer.PACIENTES:Pacientes con cáncer de colon con inestabilidad de microsatélites alta en estadio I, II, o III.INTERVENCIÓN:Resección quirúrgica con intención curativa.PRINCIPALES RESULTADOS Y MEDIDAS:Hipermetilación del promotor MLH1, inactivación bialélica, variante patógena constitucional y pérdida de proteínas específicas reparadoras de desajustes.RESULTADOS:De los 157 tumores identificados con un análisis genético completo, el 66 % tenía hipermetilación del promotor MLH1, el 18 % tenía una variante patogénica constitucional (síndrome de Lynch), el 11 % tenía variantes patogénicas somáticas bialélicas de algún gen MMR y el 6 % tenía una alta inestabilidad de microsatélites sin explicación. La distribución de la pérdida según la proteína de reparación del desajuste fue la siguiente: pérdida conjunta de MLH1 y PMS2, 79 % de los tumores; co-pérdida de MSH2 y MSH6, 10%; MSH6 solo, 3%; PMS2 solo, 2%; otras combinaciones, 2%; sin pérdida, 2%. La carga mutacional del tumor fue más baja en los tumores deficientes en MLH1 y PMS2. Los tumores con deficiencia de MSH6 tenían los niveles más bajos de linfocitos infiltrantes de tumores, las puntuaciones más bajas del sensor de IMS y la menor cantidad de deleciones por cambio de marco. Los pacientes con hipermetilación del promotor MLH1 tenían significativamente más probabilidades de ser mayores y mujeres y de tener lesiones en el colon derecho que los pacientes con inactivación bialélica. La mutación fue el segundo golpe más frecuente en tumores con inactivación bialélica y tumores de pacientes con síndrome de Lynch.LIMITACIONES:Sesgo potencial de selección o referencia, datos faltantes para algunos pacientes y tamaños relativamente pequeños de algunos subgrupos.CONCLUSIONES:Las características clínicas del cáncer de colon deficiente en reparación de desajustes varían con la etiología de la inestabilidad de microsatélites, y sus características moleculares varían con la proteína de reparación de desajustes afectada. Vea Resumen de video en http://links.lww.com/DCR/B984 . (Traducción-Dr. Felipe Bellolio ).

Genomic and transcriptomic determinants of response to neoadjuvant therapy in rectal cancer.

The incidence of rectal cancer is increasing in patients younger than 50 years. Locally advanced rectal cancer is still treated with neoadjuvant radiation, chemotherapy and surgery, but recent evidence suggests that patients with a complete response can avoid surgery permanently. To define correlates of response to neoadjuvant therapy, we analyzed genomic and transcriptomic profiles of 738 untreated rectal cancers. APC mutations were less frequent in the lower than in the middle and upper rectum, which could explain the more aggressive behavior of distal tumors. No somatic alterations had significant associations with response to neoadjuvant therapy in a treatment-agnostic manner, but KRAS mutations were associated with faster relapse in patients treated with neoadjuvant chemoradiation followed by consolidative chemotherapy. Overexpression of IGF2 and L1CAM was associated with decreased response to neoadjuvant therapy. RNA-sequencing estimates of immune infiltration identified a subset of microsatellite-stable immune hot tumors with increased response and prolonged disease-free survival.

Intratumoral T-cell repertoires in DNA mismatch repair-proficient and -deficient colon tumors containing high or low numbers of tumor-infiltrating lymphocytes.

Colon tumors with deficient DNA mismatch repair (dMMR) are generally infiltrated by T cells more densely than tumors with proficient mismatch repair (pMMR). However, high numbers of tumor-infiltrating lymphocytes (TILs) are found in select pMMR tumors, and low numbers of TILs are seen in select dMMR tumors. In this study, we compared T-cell repertoires in 20 pMMR and 27 dMMR colon tumors with high and low TIL counts. We found that T cells in dMMR tumors are more clonal and their repertoire is less rich compared with T cells in pMMR tumors. In the dMMR group, T cells in TIL-high tumors were more clonal and their repertoire was less rich compared with T cells in TIL-low tumors, but in the pMMR group, T-cell diversity in TIL-high tumors was comparable to T-cell diversity in TIL-low tumors. These findings suggest that T cells clonally expand in dMMR tumors, possibly in response to MMR deficiency-induced tumor neoantigens.

Programme of self-reactive innate-like T cell-mediated cancer immunity.

Cellular transformation induces phenotypically diverse populations of tumour-infiltrating T cells1-5, and immune checkpoint blockade therapies preferentially target T cells that recognize cancer cell neoantigens6,7. Yet, how other classes of tumour-infiltrating T cells contribute to cancer immunosurveillance remains elusive. Here, in a survey of T cells in mouse and human malignancies, we identified a population of αß T cell receptor (TCR)-positive FCER1G-expressing innate-like T cells with high cytotoxic potential8 (ILTCKs). These cells were broadly reactive to unmutated self-antigens, arose from distinct thymic progenitors following early encounter with cognate antigens, and were continuously replenished by thymic progenitors during tumour progression. Notably, expansion and effector differentiation of intratumoural ILTCKs depended on interleukin-15 (IL-15) expression in cancer cells, and inducible activation of IL-15 signalling in adoptively transferred ILTCK progenitors suppressed tumour growth. Thus, the antigen receptor self-reactivity, unique ontogeny, and distinct cancer cell-sensing mechanism distinguish ILTCKs from conventional cytotoxic T cells, and define a new class of tumour-elicited immune response.

KRAS Mutants Upregulate Integrin ß4 to Promote Invasion and Metastasis in Colorectal Cancer.

KRAS mutation in colorectal cancer is associated with aggressive tumor behavior through increased invasiveness and higher rates of lung metastases, but the biological mechanisms behind these features are not fully understood. In this study, we show that KRAS-mutant colorectal cancer upregulates integrin α6ß4 through ERK/MEK signaling. Knocking-out integrin ß4 (ITGB4) specifically depleted the expression of integrin α6ß4 and this resulted in a reduction in the invasion and migration ability of the cancer cells. We also observed a reduction in the number and area of lung metastatic foci in mice that were injected with ITGB4 knockout KRAS-mutant colorectal cancer cells compared with the mice injected with ITGB4 wild-type KRAS-mutant colorectal cancer cells, while no difference was observed in liver metastases. Inhibiting integrin α6ß4 in KRAS-mutant colorectal cancer could be a potential therapeutic target to diminish the KRAS-invasive phenotype and associated pulmonary metastasis rate. IMPLICATIONS: Knocking-out ITGB4, which is overexpressed in KRAS-mutant colorectal cancer and promotes tumor aggressiveness, diminishes local invasiveness and rates of pulmonary metastasis.

Survival After Induction Chemotherapy and Chemoradiation Versus Chemoradiation and Adjuvant Chemotherapy for Locally Advanced Rectal Cancer.

BACKGROUND: Total neoadjuvant therapy (TNT) improves tumor response in locally advanced rectal cancer (LARC) patients compared to neoadjuvant chemoradiotherapy alone. The effect of TNT on patient survival has not been fully investigated. MATERIALS AND METHODS: This was a retrospective case series of patients with LARC at a comprehensive cancer center. Three hundred and eleven patients received chemoradiotherapy (chemoRT) as the sole neoadjuvant treatment and planned adjuvant chemotherapy, and 313 received TNT (induction fluorouracil and oxaliplatin-based chemotherapy followed by chemoradiotherapy in the neoadjuvant setting). These patients then underwent total mesorectal excision or were entered in a watch-and-wait protocol. The proportion of patients with complete response (CR) after neoadjuvant therapy (defined as pathological CR or clinical CR sustained for 2 years) was compared by the χ2 test. Disease-free survival (DFS), local recurrence-free survival, distant metastasis-free survival, and overall survival were assessed by Kaplan-Meier analysis and log-rank test. Cox regression models were used to further evaluate DFS. RESULTS: The rate of CR was 20% for chemoRT and 27% for TNT (P=.05). DFS, local recurrence-free survival, metastasis-free survival, and overall survival were no different. Disease-free survival was not associated with the type of neoadjuvant treatment (hazard ratio [HR] 1.3; 95% confidence interval [CI] 0.93-1.80; P = .12). CONCLUSIONS: Although TNT does not prolong survival than neoadjuvant chemoradiotherapy plus intended postoperative chemotherapy, the higher response rate associated with TNT may create opportunities to preserve the rectum in more patients with LARC.

An immunocompetent rectal cancer model to study radiation therapy.

We describe a mouse model of rectal cancer (RC) involving rapid tumor organoid engraftment via orthotopic transplantation in an immunocompetent setting. This approach uses simple mechanical disruption to allow engraftment, avoiding the use of dextran sulfate sodium. The resulting RC tumors invaded from the mucosal surface and metastasized to distant organs. Histologically, the tumors closely resemble human RC and mirror remodeling of the tumor microenvironment in response to radiation. This murine RC model thus recapitulates key aspects of human RC pathogenesis and presents an accessible approach for more physiologically accurate, preclinical efficacy studies.

Identifying Diagnostic MicroRNAs and Investigating Their Biological Implications in Rectal Cancer.

Importance: Accurate clinical staging is important in rectal cancer because it determines the appropriate treatment and prognosis. Despite the use of multiple diagnostic imaging tools, it is sometimes difficult to clinically distinguish stage I tumors from stage II or III locally advanced disease. Identification of differentiating microRNAs (miRNAs) between these 2 groups may improve the clinical diagnostic power and provide insight into the biology of tumor progression. Objectives: To investigate differences in the expression of miRNAs in stage I vs stage II or III rectal cancers and integrate matched mRNA profiling data to identify possible functional roles of these miRNAs. Design, Setting, and Participants: The primary tumor specimens from patients who were enrolled in 2 prospective clinical trials between March 24, 2004, and November 16, 2012 (American College of Surgeons Oncology Group [ACOSOG] Z6041 and Timing of Rectal Cancer Response to Chemoradiation [TIMING]) were sequenced to arrive at a set of 127 cases (41 stage I and 86 stage II or III tumors) with matched miRNA and messenger RNA (mRNA) profiling data. These findings were also evaluated in an independent cohort of 127 patient specimens (29 stage I and 98 stage II or III tumors) from The Cancer Genome Atlas Rectum Adenocarcinoma (TCGA-READ) that also had matched miRNA and mRNA data. Data analysis was performed from September 1, 2019, to September 1, 2020. Main Outcomes and Measures: Alterations in miRNA expression between stage I and stage II or III tumors and their potential gene targets. Results: A total of 254 pretreatment rectal adenocarcinoma specimens were analyzed in this study as 2 distinct cohorts: 127 samples in the ACOSOG/TIMING (stage I group: 27 [66%] male; mean [SD] age, 64.4 [10.8] years; stage II or III group: 47 [55%] male; mean [SD] age, 57.0 [11.4] years), and another 127 samples from TCGA-READ (stage I group: 17 [59%] male; mean [SD] age, 63.6 [12.0] years; stage II or III group: 48 [49%] male; mean [SD] age, 64.5 [11.4] years). A total of 19 miRNAs were overexpressed in stage II or III vs stage I tumors in both cohorts. This miRNA signature had an excellent discriminative value for distinguishing stage II or III from stage I rectal tumors (area under the curve, 0.88; 95% CI, 0.83-0.94 in ACOSOG/TIMING cohort and area under the curve, 0.84; 95% CI, 0.77-0.91 in the TCGA-READ cohort). Integrative analysis revealed 3 miRNA-mRNA pairs that exhibited significant correlations in both cohorts: miR-31-5p-SATB2, miR-143-3p-KLF5, and miR-204-5p-EZR. Conclusions and Relevance: This diagnostic study found that many of the dysregulated miRNAs in stage II or III vs stage I rectal cancers have biological implications for tumor progression. The results of this study suggest that these miRNAs could assist as diagnostic biomarkers to better identify patients with locally advanced rectal cancer.

Tumor-Infiltrating Lymphocytes, Tumor Mutational Burden, and Genetic Alterations in Microsatellite Unstable, Microsatellite Stable, or Mutant POLE/POLD1 Colon Cancer.

To characterize the relationship between tumor-infiltrating lymphocytes (TIL), tumor mutational burden (TMB), and genetic alterations in microsatellite stable (MSS), microsatellite instability (MSI), or mutant POLE/POLD1 colon cancer. MATERIALS AND METHODS: Four hundred ninety-nine resected stage I-III colon tumors treated between 2014 and 2019 were assessed for TIL; somatic mutations, copy number alterations, and structural changes in > 400 oncogenes; and MSI status. RESULTS: Of the 499 tumors analyzed, 313 were MSS, 175 were MSI, and 11 had POLE/POLD1 pathogenic mutations. Both the percentage of tumors with a high level of TIL (≥ 4 lymphocytes per high-power field) and the median TMB differed significantly between the three phenotypes: MSS, 4.5% and 6 mutations/Mb; MSI, 68% and 54 mutations/Mb; POLE/POLD1, 82% and 158 mutations/Mb (P < .05). Within each phenotype, TMB did not vary significantly with TIL level. Among MSI tumors, the median number of frameshift indels was significantly higher in tumors with high levels of TIL (20 v 17; P = .018). In the MSS group, significantly higher proportions of tumors with high levels of TIL had mutations in the transforming growth factor-ß (36% v 12%; P = .01), RAS (86% v 54%; P = .02), and Hippo (7% v 1%; P = .046) pathways; in contrast, TP53 alterations were associated with low levels of TIL (74% v 43%; P = .01). CONCLUSION: The association between TIL, TMB, and genetic alterations varies significantly between MSI, MSS, and mutant POLE/POLD1 colon tumors. These differences may help explain tumoral immunity and lead to predictors of response to immunotherapy.

KRAS mutant rectal cancer cells interact with surrounding fibroblasts to deplete the extracellular matrix.

Somatic mutations in the KRAS oncogene are associated with poor outcomes in locally advanced rectal cancer but the underlying biologic mechanisms are not fully understood. We profiled mRNA in 76 locally advanced rectal adenocarcinomas from patients that were enrolled in a prospective clinical trial and investigated differences in gene expression between KRAS mutant (KRAS-mt) and KRAS-wild-type (KRAS-wt) patients. We found that KRAS-mt tumors display lower expression of genes related to the tumor stroma and remodeling of the extracellular matrix. We validated our findings using samples from The Cancer Genome Atlas (TCGA) and also by performing immunohistochemistry (IHC) and immunofluorescence (IF) in orthogonal cohorts. Using in vitro and in vivo models, we show that oncogenic KRAS signaling within the epithelial cancer cells modulates the activity of the surrounding fibroblasts in the tumor microenvironment.

A rectal cancer organoid platform to study individual responses to chemoradiation.

Rectal cancer (RC) is a challenging disease to treat that requires chemotherapy, radiation and surgery to optimize outcomes for individual patients. No accurate model of RC exists to answer fundamental research questions relevant to patients. We established a biorepository of 65 patient-derived RC organoid cultures (tumoroids) from patients with primary, metastatic or recurrent disease. RC tumoroids retained molecular features of the tumors from which they were derived, and their ex vivo responses to clinically relevant chemotherapy and radiation treatment correlated with the clinical responses noted in individual patients' tumors. Upon engraftment into murine rectal mucosa, human RC tumoroids gave rise to invasive RC followed by metastasis to lung and liver. Importantly, engrafted tumors displayed the heterogenous sensitivity to chemotherapy observed clinically. Thus, the biology and drug sensitivity of RC clinical isolates can be efficiently interrogated using an organoid-based, ex vivo platform coupled with in vivo endoluminal propagation in animals.

Exploring the factors that influence physician technostress from using mobile electronic medical records.

This paper proposes an integrated model for investigating how physicians' perceived individual and technology characteristics affect their technological stress (technostress) that is derived from using mobile electronic medical records (MEMRs). Individual characteristics comprise constructs of mobile self-efficacy and technology dependence, whereas perceived technology characteristics comprise constructs of perceived usefulness, complexity, and reliability. We employed the survey method to collect 158 valid questionnaires from physicians working at three branch hospitals to determine perceptions regarding MEMRs, yielding a response rate of 33.62%. Partial least squares, a structural equation modeling technique, was used for model examination and hypothesis testing. The results show that physicians have a low perception of MEMR dependence and technostress. Furthermore, physicians' perceived MEMR technology dependency, mobile self-efficacy, and complexity were proven to significantly affect physician technostress when using MEMRs, whereas perceived usefulness and reliability were not. The explanatory power of the research model reached 67.8%. The results of this study provide valuable insights and significant knowledge for technostress in health care, particularly from academic and practical perspectives.

Single Nucleotide Polymorphism TGFß1 R25P Correlates with Acute Toxicity during Neoadjuvant Chemoradiotherapy in Rectal Cancer Patients.

PURPOSE: To validate the finding of an association between single nucleotide polymorphisms (SNPs) and toxicity during chemoradiotherapy (CRT) in rectal cancer patients, in an independent population. METHODS AND MATERIALS: The cohort consisted of 165 patients who received CRT for rectal cancer from 2006 to 2012. Prospectively recorded toxicity information, graded according to the Common Terminology Criteria for Adverse Events version 3.0, was retrieved from the medical record. Additionally, a subset of 52 patients recorded their gastrointestinal symptoms weekly during CRT, using the 7-item Bowel Problems Scale. Deoxyribonucleic acid was extracted from normal tissue in the proctectomy specimens and screened for 3 SNPs: XRCC1 R399Q, XPD K751Q, and TGFß1 R25P. Univariable and multivariable logistic regression models were constructed. RESULTS: The median radiation dose was 50.4 Gy, and all patients received concurrent chemotherapy. Toxicities measured by the Common Terminology Criteria for Adverse Events were closely associated with patient-reported outcomes for the patients who completed the 7-item Bowel Problems Scale. Grade ≥3 toxicity occurred during CRT in 14 patients (8%). All 14 patients had either XRCC1 R399Q or TGFß1 R25P polymorphisms. The TGFß1 R25P polymorphism was significantly associated with grade ≥3 toxicity (odds ratio [OR] 3.47, P=.04) and, in patients who completed the Bowel Problems Scale, with grade ≥4 toxicity (OR 5.61, P=.02). The latter finding persisted in a multivariable logistic regression model controlling for ethnicity, age, and sex (adjusted OR 1.83, P=.02). CONCLUSIONS: We have validated the correlation between the TGFß1 R25P SNP and acute toxicity during CRT in an independent cohort using both clinician- and patient-reported toxicity. The information from our study could be used as a basis to formulate a prospective trial testing the utility of this SNP as a biomarker of acute toxicity during neoadjuvant treatment in locally advanced rectal cancer.

KRAS and Combined KRAS/TP53 Mutations in Locally Advanced Rectal Cancer are Independently Associated with Decreased Response to Neoadjuvant Therapy.

BACKGROUND: The response of rectal cancers to neoadjuvant chemoradiation (CRT) is variable, but tools to predict response remain lacking. We evaluated whether KRAS and TP53 mutations are associated with pathologic complete response (pCR) and lymph node metastasis after adjusting for neoadjuvant regimen. METHODS: Retrospective analysis of 229 pretreatment biopsies from patients with stage II/III rectal cancer was performed. All patients received CRT. Patients received 0-8 cycles of FOLFOX either before or after CRT, but prior to surgical excision. A subset was analyzed to assess concordance between mutation calls by Sanger Sequencing and a next-generation assay. RESULTS: A total of 96 tumors (42 %) had KRAS mutation, 150 had TP53 mutation (66 %), and 59 (26 %) had both. Following neoadjuvant therapy, 59 patients (26 %) achieved pCR. Of 133 KRAS wild-type tumors, 45 (34 %) had pCR, compared with 14 of 96 (15 %) KRAS mutant tumors (p = .001). KRAS mutation remained independently associated with a lower pCR rate on multivariable analysis after adjusting for clinical stage, CRT-to-surgery interval and cycles of FOLFOX (OR 0.34; 95 % CI 0.17-0.66, p < .01). Of 29 patients with KRAS G12V or G13D, only 2 (7 %) achieved pCR. Tumors with both KRAS and TP53 mutation were associated with lymph node metastasis. The concordance between platforms was high for KRAS (40 of 43, 93 %). CONCLUSIONS: KRAS mutation is independently associated with a lower pCR rate in locally advanced rectal cancer after adjusting for variations in neoadjuvant regimen. Genomic data can potentially be used to select patients for "watch and wait" strategies.

Integrated genomic profiling identifies microRNA-92a regulation of IQGAP2 in locally advanced rectal cancer.

Locally advanced rectal cancer (LARC) is treated with chemoradiation prior to surgical excision, leaving residual tumors altered or completely absent. Integrating layers of genomic profiling might identify regulatory pathways relevant to rectal tumorigenesis and inform therapeutic decisions and further research. We utilized formalin-fixed, paraffin-embedded pre-treatment LARC biopsies (n=138) and compared copy number, mRNA, and miRNA expression with matched normal rectal mucosa. An integrative model was used to predict regulatory interactions to explain gene expression changes. These predictions were evaluated in vitro using multiple colorectal cancer cell lines. The Cancer Genome Atlas (TCGA) was also used as an external cohort to validate our genomic profiling and predictions. We found differentially expressed mRNAs and miRNAs that characterize LARC. Our integrative model predicted the upregulation of miR-92a, miR-182, and miR-221 expression to be associated with downregulation of their target genes after adjusting for the effect of copy number alterations. Cell line studies using miR-92a mimics and inhibitors demonstrate that miR-92a expression regulates IQGAP2 expression. We show that endogenous miR-92a expression is inversely associated with endogenous KLF4 expression in multiple cell lines, and that this relationship is also present in rectal cancers of TCGA. Our integrative model predicted regulators of gene expression change in LARC using pre-treatment FFPE tissues. Our methodology implicated multiple regulatory interactions, some of which are corroborated by independent lines of study, while others indicate new opportunities for investigation.

Oncolytic immunotherapy using recombinant vaccinia virus GLV-1h68 kills sorafenib-resistant hepatocellular carcinoma efficiently.

BACKGROUND: Sorafenib is the standard systemic therapy for unresectable or recurrent hepatocellular carcinoma (HCC) but adds minimal increase in survival. Therefore, there is a great need to develop novel therapies for advanced or recurrent HCC. One emerging field of cancer treatment involves oncolytic viruses that specifically infect, replicate within, and kill cancer cells. In this study, we examined the ability of GLV-1h68, a recombinant vaccinia virus derived from the vaccine strain that was used to eradicate smallpox, to kill sorafenib-resistant (SR) HCC cell lines. METHODS: Four SR HCC cell lines were generated by repeated passage in the presence of sorafenib. Median inhibitory concentration was determined for all cell lines. The infectivity, viral replication, and cytotoxicity of GLV-1h68 were assayed for both parental and SR HCC cells. RESULTS: Infectivity increased in a time and concentration-dependent manner in all cell lines. All cell lines supported efficient replication of virus. No difference between the rates of cell death between the parental and SR cell lines was observed. CONCLUSION: Our results demonstrate that the oncolytic vaccinia virus GLV-1h68 kills both parental and SR HCC cell lines efficiently. This study indicates that patients who have failed treatment with sorafenib remain viable candidates for oncolytic therapy.

c-MET and HGF mRNA expression in hepatocellular carcinoma: correlation with clinicopathological features and survival.

BACKGROUND/AIM: Data on the clinicopathological features and prognostic impact of c-N-Methyl-N'-nitro-N-nitroso-guanidine HOS Transforming gene (c-MET) and hepatocyte growth factor (HGF) in hepatocellular carcinoma (HCC) are inconsistent. We assessed c-MET and HGF expression in 49 patients with early-stage HCC and correlated the results with disease characteristics and survival. MATERIALS AND METHODS: Expression of c-MET and HGF mRNA in tumor (T) and non-tumor (NT) tissues was assessed. Results were correlated with patient characteristics and overall and recurrence-free survival. RESULTS: Median relative tumor c-MET and HGF expressions were 3.23 (T/NT ratio 6.46) and 9.07 (T/NT ratio 0.77), respectively. c-MET and HGF were overexpressed in early-stage disease with favorable characteristics although there was no association with survival. CONCLUSION: Contrary to other studies, in our series increased tumor c-MET and HGF expressions were associated with favorable disease attributes but not with survival. The prognostic and therapeutic applications of this knowledge to HCC are under active investigation.

Emergence of KRAS mutations and acquired resistance to anti-EGFR therapy in colorectal cancer.

A main limitation of therapies that selectively target kinase signalling pathways is the emergence of secondary drug resistance. Cetuximab, a monoclonal antibody that binds the extracellular domain of epidermal growth factor receptor (EGFR), is effective in a subset of KRAS wild-type metastatic colorectal cancers. After an initial response, secondary resistance invariably ensues, thereby limiting the clinical benefit of this drug. The molecular bases of secondary resistance to cetuximab in colorectal cancer are poorly understood. Here we show that molecular alterations (in most instances point mutations) of KRAS are causally associated with the onset of acquired resistance to anti-EGFR treatment in colorectal cancers. Expression of mutant KRAS under the control of its endogenous gene promoter was sufficient to confer cetuximab resistance, but resistant cells remained sensitive to combinatorial inhibition of EGFR and mitogen-activated protein-kinase kinase (MEK). Analysis of metastases from patients who developed resistance to cetuximab or panitumumab showed the emergence of KRAS amplification in one sample and acquisition of secondary KRAS mutations in 60% (6 out of 10) of the cases. KRAS mutant alleles were detectable in the blood of cetuximab-treated patients as early as 10 months before radiographic documentation of disease progression. In summary, the results identify KRAS mutations as frequent drivers of acquired resistance to cetuximab in colorectal cancers, indicate that the emergence of KRAS mutant clones can be detected non-invasively months before radiographic progression and suggest early initiation of a MEK inhibitor as a rational strategy for delaying or reversing drug resistance.

MET activation mediates resistance to lapatinib inhibition of HER2-amplified gastric cancer cells.

HER2 amplification is found in more than 15% of gastric cancers and is associated with poor clinical outcome. Lapatinib, a dual HER2 and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, has shown promising in vitro results in treating HER2(+) cancer cells. However, several studies have shown that activation of alternative receptor tyrosine kinases can mediate resistance to HER-targeted therapy. Here, we investigated whether activated MET can confer resistance to lapatinib inhibition of gastric cancer cells. A panel of gastric cancer cell lines was treated with lapatinib, and we observed that cell proliferation was reduced by 70% and that the degree of HER2 amplification corresponds to sensitivity to lapatinib. Immunoblotting analysis indicated that phosphorylation of HER2, EGFR, MET, AKT, and extracellular signal-regulated kinase was inhibited by lapatinib and presumably led to cell-cycle arrest as observed with flow cytometry. Hepatocyte growth factor (HGF) activation of MET receptors rescued cells from lapatinib-induced growth inhibition by restimulating the downstream pathways and restoring normal cell-cycle progression. This rescue effect could be abrogated by inhibiting MET with PHA-665752 (a highly specific MET inhibitor) or downregulating MET expression with short interfering RNA. No synergy in growth inhibition was observed when cells were treated with a combination of lapatinib and PHA-665752. Repeat studies using insulin-like growth factor 1 and fibroblast growth factor 3 could not uniformly rescue the lapatinib-treated gastric cancer cells. In conclusion, HGF/MET-mediated resistance to lapatinib is a novel mechanism of resistance to HER2-targeted agents in gastric cancer cells. Development of inhibitors targeting multiple receptors or common downstream signaling proteins merits further investigation.