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Clinical Cancer Research

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Clinical Cancer Research

Mutations in TP53, encoding the master tumor suppressor p53, have posed a developmental therapeutic dilemma due to inability to target loss of function. Inhibition of WEE1 or CHK1 kinase, negative regulators of the G2–M checkpoint, selectively sensitizes p53-deficient cells to exogenous DNA damage, abrogating G2 arrest and precipitating mitotic catastrophe. Clin Cancer Res; 20(16); 4173–5. ©2014 AACR.

We compiled and analyzed a database of cooperative group trials in advanced pancreatic cancer to develop historical benchmarks for overall survival (OS) and progression-free survival (PFS). Such benchmarks are essential for evaluating new therapies in a single-arm setting. The analysis included patients with untreated metastatic pancreatic cancer receiving regimens that included gemcitabine, between 1995 and 2005. Prognostic baseline factors were selected by their significance in Cox regression analysis. Outlier trial arms were identified by comparing individual 6-month OS and PFS rates against the entire group. The dataset selected for the generation of OS and PFS benchmarks was then tested for intertrial arm variability using a logistic-normal model with the selected baseline prognostic factors as fixed effects and the individual trial arm as a random effect. A total of 1,132 cases from eight trials qualified. Performance status and sex were independently significant for OS, and performance status was prognostic for PFS. Outcomes for one trial (NCCTG-034A) were significantly different from the other trial arms. When this trial was excluded, the remaining trial arms were homogeneous for OS and PFS outcomes after adjusting for performance status and sex. Benchmark values for 6-month OS and PFS are reported along with a method for using these values in future study design and analysis. The benchmark survival values were generated from a dataset that was homogeneous between trials. The benchmarks can be used to enable single-arm phase II trials using a gemcitabine platform, especially under certain circumstances. Such circumstances might be when a randomized control arm is not practically feasible, an early signal of activity of an experimental agent is being explored such as in expansion cohorts of phase I studies, and in patients who are not candidates for combination cytotoxic therapy. Clin Cancer Res; 20(16); 4176–85. ©2014 AACR.

Successful targeting of specific oncogenic "driver" mutations with small-molecule inhibitors has represented a major advance in cancer therapeutics over the past 10 to 15 years. The most common activating oncogene in human malignancy, RAS (rat sarcoma), has proved to be an elusive target. Activating mutations in RAS induce mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase–AKT pathway signaling and drive malignant progression in up to 30% of cancers. Oncogenic NRAS mutations occur in several cancer types, notably melanoma, acute myelogenous leukemia (AML), and less commonly, colon adenocarcinoma, thyroid carcinoma, and other hematologic malignancies. Although NRAS-mutant tumors have been recalcitrant to targeted therapeutic strategies historically, newer agents targeting MAP/ERK kinase 1 (MEK1)/2 have recently shown signs of clinical efficacy as monotherapy. Combination strategies of MEK inhibitors with other targeted agents have strong preclinical support and are being evaluated in clinical trials. This review discusses the recent preclinical and clinical studies about the role of NRAS in cancer, with a focus on melanoma and AML. Clin Cancer Res; 20(16); 4186–92. ©2014 AACR.

Mutations in RAS oncogenes are frequently observed in human cancers, and the mutations result in activation of the RAS–RAF–MEK–ERK pathway, leading to cell proliferation and survival. The pathway is, therefore, a potent therapeutic target in the RAS-mutant cancers. MEK inhibitors can specifically block the pathway and are one of the key types of drugs for the treatment of the RAS-mutant cancers. As RAS proteins activate other downstream signaling proteins in addition to the RAS–RAF–MEK–ERK pathway, combination therapeutic approaches with MEK inhibitors are also being evaluated. Moreover, MEK inhibitors can arrest cancer cells in G1 phase and repress prosurvival Bcl2 family proteins such as MCL1 and BCL2/BCLXL, and increase expression of Bim, a proapoptotic BH3-only family protein. This mechanism may explain the efficacy of the combination of MEK inhibitors with cytotoxic agents or other targeted inhibitors. A better understanding of the pathway will help us with development of rational combinations for the treatment of the RAS-mutant cancers. Clin Cancer Res; 20(16); 4193–9. ©2014 AACR.

Despite successful primary tumor treatment, the development of pulmonary metastasis continues to be the most common cause of mortality in patients with osteosarcoma. A conventional drug development path requiring drugs to induce regression of established lesions has not led to improvements for patients with osteosarcoma in more than 30 years. On the basis of our growing understanding of metastasis biology, it is now reasonable and essential that we focus on developing therapeutics that target metastatic progression. To advance this agenda, a meeting of key opinion leaders and experts in the metastasis and osteosarcoma communities was convened in Bethesda, Maryland. The goal of this meeting was to provide a "Perspective" that would establish a preclinical translational path that could support the early evaluation of potential therapeutic agents that uniquely target the metastatic phenotype. Although focused on osteosarcoma, the need for this perspective is shared among many cancer types. The consensus achieved from the meeting included the following: the biology of metastatic progression is associated with metastasis-specific targets/processes that may not influence grossly detectable lesions; targeting of metastasis-specific processes is feasible; rigorous preclinical data are needed to support translation of metastasis-specific agents into human trials where regression of measurable disease is not an expected outcome; preclinical data should include an understanding of mechanism of action, validation of pharmacodynamic markers of effective exposure and response, the use of several murine models of effectiveness, and where feasible the inclusion of the dog with naturally occurring osteosarcoma to define the activity of new drugs in the micrometastatic disease setting. Clin Cancer Res; 20(16); 4200–9. ©2014 AACR.

Anticancer drugs are combined in an effort to treat a heterogeneous tumor or to maximize the pharmacodynamic effect. The development of combination regimens, while desirable, poses unique challenges. These include the selection of agents for combination therapy that may lead to improved efficacy while maintaining acceptable toxicity, the design of clinical trials that provide informative results for individual agents and combinations, and logistic and regulatory challenges. The phase I trial is often the initial step in the clinical evaluation of a combination regimen. In view of the importance of combination regimens and the challenges associated with developing them, the Clinical Trial Design (CTD) Task Force of the National Cancer Institute Investigational Drug Steering Committee developed a set of recommendations for the phase I development of a combination regimen. The first two recommendations focus on the scientific rationale and development plans for the combination regimen; subsequent recommendations encompass clinical design aspects. The CTD Task Force recommends that selection of the proposed regimens be based on a biologic or pharmacologic rationale supported by clinical and/or robust and validated preclinical evidence, and accompanied by a plan for subsequent development of the combination. The design of the phase I clinical trial should take into consideration the potential pharmacokinetic and pharmacodynamic interactions as well as overlapping toxicity. Depending on the specific hypothesized interaction, the primary endpoint may be dose optimization, pharmacokinetics, and/or pharmacodynamics (i.e., biomarker). Clin Cancer Res; 20(16); 4210–7. ©2014 AACR.

Purpose: Orteronel (TAK-700) is an investigational, nonsteroidal, oral, inhibitor of androgen synthesis with greater specificity for 17,20-lyase than for 17α-hydroxylase. We investigated orteronel without steroids in patients with nonmetastatic castration-resistant prostate cancer (nmCRPC; M0).

Experimental Design: Patients with nmCRPC and rising prostate-specific antigen (PSA) received orteronel 300 mg twice daily until PSA progression, metastases, or unacceptable toxicity. The primary endpoint was percentage of patients achieving PSA ≤0.2 ng/mL (undetectable levels) at 3 months. Secondary endpoints included safety, PSA response, time to metastases, and correlated endpoints.

Results: Thirty-nine patients with a median baseline PSA doubling time of 2.4 months (range, 0.9–9.2) received a median of fourteen 28-day treatment cycles. PSA decreased >30% in 35 patients and 6 (16%) achieved PSA ≤ 0.2 ng/mL at 3 months. Median times to PSA progression and metastasis were 13.8 and 25.4 months, respectively. Kaplan–Meier estimates of freedom from PSA progression were 57% and 42% at 12 and 24 months, and of freedom from metastasis were 94% and 62% at 12 and 24 months, respectively. At 3 months, median testosterone declined by 89% from baseline. Adverse events led to therapy discontinuation in 12 patients and grade ≥3/4 adverse events occurred in 22 patients. Most frequent all-cause adverse events included fatigue (64%), hypertension (44%), diarrhea (38%), and nausea (33%), which were primarily grade 1/2.

Conclusions: Single-agent orteronel produced marked and durable declines in PSA in patients with nmCRPC. Orteronel has moderate but manageable toxicities and its chronic administration without steroids appears feasible. Clin Cancer Res; 20(16); 4218–27. ©2014 AACR.

Purpose: We performed a phase I trial to investigate the safety, clinical responses, and Wilms' tumor 1 (WT1)-specific immune responses following treatment with dendritic cells (DC) pulsed with a mixture of three types of WT1 peptides, including both MHC class I and II–restricted epitopes, in combination with chemotherapy.

Experimental Design: Ten stage IV patients with pancreatic ductal adenocarcinoma (PDA) and 1 patient with intrahepatic cholangiocarcinoma (ICC) who were HLA-positive for A*02:01, A*02:06, A*24:02, DRB1*04:05, DRB1*08:03, DRB1*15:01, DRB1*15:02, DPB1*05:01, or DPB1*09:01 were enrolled. The patients received one course of gemcitabine followed by biweekly intradermal vaccinations with mature DCs pulsed with MHC class I (DC/WT1-I; 2 PDA and 1 ICC), II (DC/WT1-II; 1 PDA), or I/II–restricted WT1 peptides (DC/WT1-I/II; 7 PDA), and gemcitabine.

Results: The combination therapy was well tolerated. WT1-specific IFN-producing CD4+ T cells were significantly increased following treatment with DC/WT1-I/II. WT1 peptide-specific delayed-type hypersensitivity (DTH) was detected in 4 of the 7 patients with PDA vaccinated with DC/WT1-I/II and in 0 of the 3 patients with PDA vaccinated with DC/WT1-I or DC/WT1-II. The WT1-specific DTH-positive patients showed significantly improved overall survival (OS) and progression-free survival (PFS) compared with the negative control patients. In particular, all 3 patients with PDA with strong DTH reactions had a median OS of 717 days.

Conclusions: The activation of WT1-specific immune responses by DC/WT1-I/II combined with chemotherapy may be associated with disease stability in advanced pancreatic cancer. Clin Cancer Res; 20(16); 4228–39. ©2014 AACR.

Purpose: Panitumumab, a fully human anti-epidermal growth factor receptor monoclonal antibody (mAb), has demonstrated efficacy in patients with wild-type KRAS metastatic colorectal cancer (mCRC). Rilotumumab and ganitumab are investigational, fully human mAbs against hepatocyte growth factor (HGF)/scatter factor and IGF1R, respectively. Here we evaluate combining rilotumumab or ganitumab with panitumumab in previously treated patients with wild-type KRAS mCRC.

Experimental Design: Part 1 was a phase Ib dose-finding study of panitumumab plus rilotumumab. The primary endpoint was the incidence of dose-limiting toxicities (DLT). Part 2 was a randomized phase II trial of panitumumab in combination with rilotumumab, ganitumab, or placebo. The primary endpoint was objective response rate (ORR); safety, progression-free survival (PFS), and overall survival (OS) were secondary endpoints. Archival tissue specimens were collected for exploratory correlative work.

Results: In part 1, no DLTs were reported. A recommended phase II dose of 10 mg/kg rilotumumab was selected. In part 2, for the panitumumab plus rilotumumab (n = 48), panitumumab plus ganitumab (n = 46), and panitumumab plus placebo arms (n = 48), the ORRs were 31%, 22%, and 21%, respectively. The median PFS was 5.2, 5.3, and 3.7 months and median OS 13.8, 10.6, and 11.6 months, respectively. Adverse events were tolerable. Exploratory biomarker analyses, including MET and IGF-related protein expression, failed to indicate conclusive predictive evidence on efficacy endpoints.

Conclusions: Panitumumab plus rilotumumab met the prespecified criterion for improvement in ORR whereas ganitumab did not. This is the first study to suggest a benefit for combining an HGF inhibitor (rilotumumab) with panitumumab in previously treated patients with wild-type KRAS mCRC. Clin Cancer Res; 20(16); 4240–50. ©2014 AACR.

Purpose: This phase I expansion study assessed safety, pharmacodynamic effects, and antitumor activity of RO4987655, a pure MEK inhibitor, in selected patients with advanced solid tumor.

Experimental Design: We undertook a multicenter phase I two-part study (dose escalation and cohort expansion). Here, we present the part 2 expansion that included melanoma, non–small cell lung cancer (NSCLC), and colorectal cancer with oral RO4987655 administered continuously at recommended doses of 8.5 mg twice daily until progressive disease (PD). Sequential tumor sampling investigated multiple markers of pathway activation/tumor effects, including ERK phosphorylation and Ki-67 expression. BRAF and KRAS testing were implemented as selection criteria and broader tumor mutational analysis added.

Results: Ninety-five patients received RO4987655, including 18 BRAF-mutant melanoma, 23 BRAF wild-type melanoma, 24 KRAS-mutant NSCLC, and 30 KRAS-mutant colorectal cancer. Most frequent adverse events were rash, acneiform dermatitis, and gastrointestinal disorders, mostly grade 1/2. Four (24%) of 17 BRAF-mutated melanoma had partial response as did four (20%) of 20 BRAF wild-type melanoma and two (11%) of 18 KRAS-mutant NSCLC. All KRAS-mutant colorectal cancer developed PD. Paired tumor biopsies demonstrated reduced ERK phosphorylation among all cohorts but significant differences among cohorts in Ki-67 modulation. Sixty-nine percent showed a decrease in fluorodeoxyglucose uptake between baseline and day 15. Detailed mutational profiling confirmed RAS/RAF screening and identified additional aberrations (NRAS/non-BRAF melanomas; PIK3CA/KRAS colorectal cancer) without therapeutic implications.

Conclusions: Safety profile of RO4987655 was comparable with other MEK inhibitors. Single-agent activity was observed in all entities except colorectal cancer. Evidence of target modulation and early biologic activity was shown among all indications independent of mutational status. Clin Cancer Res; 20(16); 4251–61. ©2014 AACR.

Purpose: Immunotherapy using vaccines or adoptively transferred tumor-infiltrating lymphocytes (TIL) is limited by T-cell functional inactivation within the solid tumor microenvironment. The purpose of this study was to determine whether a similar tumor-induced inhibition occurred with genetically modified cytotoxic T cells expressing chimeric antigen receptors (CAR) targeting tumor-associated antigens.

Experimental Design: Human T cells expressing CAR targeting mesothelin or fibroblast activation protein and containing CD3 and 4–1BB cytoplasmic domains were intravenously injected into immunodeficient mice bearing large, established human mesothelin-expressing flank tumors. CAR TILs were isolated from tumors at various time points and evaluated for effector functions and status of inhibitory pathways.

Results: CAR T cells were able to traffic into tumors with varying efficiency and proliferate. They were able to slow tumor growth, but did not cause regressions or cures. The CAR TILs underwent rapid loss of functional activity that limited their therapeutic efficacy. This hypofunction was reversible when the T cells were isolated away from the tumor. The cause of the hypofunction seemed to be multifactorial and was associated with upregulation of intrinsic T-cell inhibitory enzymes (diacylglycerol kinase and SHP-1) and the expression of surface inhibitory receptors (PD1, LAG3, TIM3, and 2B4).

Conclusions: Advanced-generation human CAR T cells are reversibly inactivated within the solid tumor microenvironment of some tumors by multiple mechanisms. The model described here will be an important tool for testing T cell–based strategies or systemic approaches to overcome this tumor-induced inhibition. Our results suggest that PD1 pathway antagonism may augment human CAR T-cell function. Clin Cancer Res; 20(16); 4262–73. ©2014 AACR.

Purpose: To identify novel therapeutic drug targets for p53-mutant head and neck squamous cell carcinoma (HNSCC).

Experimental Design: RNAi kinome viability screens were performed on HNSCC cells, including autologous pairs from primary tumor and recurrent/metastatic lesions, and in parallel on murine squamous cell carcinoma (MSCC) cells derived from tumors of inbred mice bearing germline mutations in Trp53, and p53 regulatory genes: Atm, Prkdc, and p19Arf. Cross-species analysis of cell lines stratified by p53 mutational status and metastatic phenotype was used to select 38 kinase targets. Both primary and secondary RNAi validation assays were performed on additional HNSCC cell lines to credential these kinase targets using multiple phenotypic endpoints. Kinase targets were also examined via chemical inhibition using a panel of kinase inhibitors. A preclinical study was conducted on the WEE1 kinase inhibitor, MK-1775.

Results: Our functional kinomics approach identified novel survival kinases in HNSCC involved in G2–M cell-cycle checkpoint, SFK, PI3K, and FAK pathways. RNAi-mediated knockdown and chemical inhibition of the WEE1 kinase with a specific inhibitor, MK-1775, had a significant effect on both viability and apoptosis. Sensitivity to the MK-1775 kinase inhibitor is in part determined by p53 mutational status, and due to unscheduled mitotic entry. MK-1775 displays single-agent activity and potentiates the efficacy of cisplatin in a p53-mutant HNSCC xenograft model.

Conclusions: WEE1 kinase is a potential therapeutic drug target for HNSCC. This study supports the application of a functional kinomics strategy to identify novel therapeutic targets for cancer. Clin Cancer Res; 20(16); 4274–88. ©2014 AACR.

Purpose: How tumors evade or suppress immune surveillance is a key question in cancer research, and overcoming immune escape is a major goal for lengthening remission after cancer treatment. Here, we used the papillomavirus-associated rabbit auricular VX2 carcinoma, a model for studying human head and neck cancer, to reveal the mechanisms underlying the antitumorigenic effects of intraperitoneal oxidative stress following O3/O2-pneumoperitoneum (O3/O2-PP) treatment.

Experimental Design: Solid auricular VX2 tumors were induced in immune-competent adult New Zealand White Rabbits. Animals were O3/O2-PP- or sham-treated, after which they underwent tumor ablation upon reaching no-go criteria. CD3+ tumor-infiltrating lymphocytes (TIL) were evaluated by immunohistochemistry, and expression levels of 84 immune response genes were measured by quantitative real-time PCR. Adoptive transfer of peripheral blood leukocytes (PBL)—derived from animals with tumor regression—into control animals with progressing tumors was implemented to assess acquired tumor resistance functionally.

Results: Auricular VX2 tumors regressing after O3/O2-PP treatment exhibited increased levels of CD3+ TILs; they also exhibited enhanced expression of genes that encode receptors involved in pattern recognition, molecules that are required for antigen presentation and T cell activation, and inflammatory mediators. Adoptive cell transfer of PBLs from donor rabbits with regressing tumors to recipient rabbits with newly implanted VX2 carcinoma resulted in acquired tumor resistance of the host and tumor regression.

Conclusion: Intraperitoneal oxidative stress effectively converts the immune response against the papillomavirus-associated rabbit VX2 carcinoma from tumor permissive to tumoricidal and leads to a sustainable, adoptively transferable oncolytic immune response. Clin Cancer Res; 20(16); 4289–301. ©2014 AACR.

Purpose: The selective killing of tumor cells is an important strategy for cancer therapeutics. The aim of this study was to develop a novel antitumor agent that is safe for normal cells with the ability to selectively target cancer cells.

Experimental Design: On the basis of quantitative structure–activity relationship, we synthesized a novel polyphenol conjugate (E)-3-(3,5-dimethoxyphenyl)-1-(2-methoxyphenyl)prop-2-en-1-one (DPP-23). We evaluated the effect of DPP-23 on proliferation, cell cycle, and apoptosis in various tumor cells. We also assessed molecular targets of DPP-23 using genome-wide expression profiling by DNA microarray and real-time PCR array systems.

Results: DPP-23 effectively inhibited the growth of cancer cells in vitro and in vivo (xenografts in Balb/c nude mice). At a molecular level, DPP-23 targeted the unfolded protein response (UPR) in the endoplasmic reticulum (ER) through the production of reactive oxygen species (ROS) in cancer cells, but not in normal cells, resulting in selective killing of tumor cells via caspase-dependent apoptosis.

Conclusions: The selective generation of ROS in cancer cells could be an attractive strategy for the selective killing of cancer cells, while maintaining negligible cytotoxicity to normal cells. DPP-23 represents a promising novel therapeutic agent for the selective production of ROS in cancer cells. Clin Cancer Res; 20(16); 4302–13. ©2014 AACR.

Purpose: Patients with luminal breast cancer (LBC) often become endocrine resistant over time. We investigated the molecular changes associated with acquired hormonoresistances in patient-derived xenografts of LBC.

Experimental Design: Two LBC xenografts (HBCx22 and HBCx34) were treated with different endocrine treatments (ET) to obtain xenografts with acquired resistances to tamoxifen (TamR) and ovariectomy (OvaR). PI3K pathway activation was analyzed by Western blot analysis and IHC and responses to ET combined to everolimus were investigated in vivo. Gene expression analyses were performed by RT-PCR and Affymetrix arrays.

Results: HBCx22 TamR xenograft was cross-resistant to several hormonotherapies, whereas HBCx22 OvaR and HBCx34 TamR exhibited a treatment-specific resistance profile. PI3K pathway was similarly activated in parental and resistant xenografts but the addition of everolimus did not restore the response to tamoxifen in TamR xenografts. In contrast, the combination of fulvestrant and everolimus induced tumor regression in vivo in HBCx34 TamR, where we found a cross-talk between the estrogen receptor (ER) and PI3K pathways. Expression of several ER-controlled genes and ER coregulators was significantly changed in both TamR and OvaR tumors, indicating impaired ER transcriptional activity. Expression changes associated with hormonoresistance were both tumor and treatment specific and were enriched for genes involved in cell growth, cell death, and cell survival.

Conclusions: PDX models of LBC with acquired resistance to endocrine therapies show a great diversity of resistance phenotype, associated with specific deregulations of ER-mediated gene transcription. These models offer a tool for developing anticancer therapies and to investigate the dynamics of resistance emerging during pharmacologic interventions. Clin Cancer Res; 20(16); 4314–25. ©2014 AACR.

Purpose: Pancreatic cancer is characterized by stromal desmoplasia and perineural invasion (PNI). We sought to explore the contribution of pancreatic stellate cells (PSC) activated by paracrine Sonic Hedgehog (SHH) in pancreatic cancer PNI and progression.

Experimental Design: In this study, the expression dynamics of SHH were examined via immunohistochemistry, real-time PCR, and Western blot analysis in a cohort of carcinomatous and nonneoplastic pancreatic tissues and cells. A series of in vivo and in vitro assays was performed to elucidate the contribution of PSCs activated by paracrine SHH signaling in pancreatic cancer PNI and progression.

Results: We show that SHH overexpression in tumor cells is involved in PNI in pancreatic cancer and is an important marker of biologic activity of pancreatic cancer. Moreover, the overexpression of SHH in tumor cells activates the hedgehog pathway in PSCs in the stroma instead of activating tumor cells. These activated PSCs are essential for the promotion of pancreatic cancer cell migration along nerve axons and nerve outgrowth to pancreatic cancer cell colonies in an in vitro three-dimensional model of nerve invasion in cancer. Furthermore, the coimplantation of PSCs activated by paracrine SHH induced tumor cell invasion of the trunk and nerve dysfunction along sciatic nerves and also promoted orthotropic xenograft tumor growth, metastasis, and PNI in in vivo models.

Conclusions: These results establish that stromal PSCs activated by SHH paracrine signaling in pancreatic cancer cells secrete high levels of PNI-associated molecules to promote PNI in pancreatic cancer. Clin Cancer Res; 20(16); 4326–38. ©2014 AACR.

Purpose: Atopic dermatitis is characterized by decreased expression of filaggrin and loricrin. Patients with atopic dermatitis often suffer from skin infections, which are also frequently seen in patients with cutaneous T-cell lymphoma (CTCL). In this study, we aimed to investigate the skin barrier in CTCL.

Experimental Design: We assessed skin moisture and transepidermal water loss (TEWL) in patients with CTCL. We next examined mRNA expression levels of filaggrin, loricrin, and antimicrobial peptides (AMP) in skin samples of CTCL, using skin from healthy volunteers and patients with atopic dermatitis or psoriasis as controls. Immunostainings for filaggrin, loricrin, and S100 proteins were also performed.

Results: Lower levels of skin moisture accompanied by higher levels of TEWL were seen in lesional skin of CTCL than in normal skin. CTCL lesional skin contained lower levels of filaggrin and loricrin mRNA than normal skin, which was also true with atopic dermatitis and psoriatic skin. mRNA expression levels of filaggrin in CTCL skin negatively correlated with disease severity markers. Expression levels of AMPs in lesional skin of CTCL and atopic dermatitis were significantly lower than in psoriatic skin. Immunohistochemistry confirmed decreased expression of filaggrin and loricrin in CTCL, atopic dermatitis, and psoriatic skin and enhanced expression of S100 proteins in psoriatic skin.

Conclusions: Our results show that there is barrier dysfunction in CTCL skin, similar to what is seen with atopic dermatitis skin. In addition, low AMP expression in CTCL skin was documented when compared with psoriatic skin, which may explain frequent infections that can occur in patients with CTCL. Clin Cancer Res; 20(16); 4339–48. ©2014 AACR.

Purpose: Even though recent studies have shown that genetic changes at enhancers can influence carcinogenesis, most methylomic studies have focused on changes at promoters. We used renal cell carcinoma (RCC), an incurable malignancy associated with mutations in epigenetic regulators, as a model to study genome-wide patterns of DNA methylation at a high resolution.

Experimental Design: Analysis of cytosine methylation status of 1.3 million CpGs was determined by the HELP assay in RCC and healthy microdissected renal tubular controls.

Results: We observed that the RCC samples were characterized by widespread hypermethylation that preferentially affected gene bodies. Aberrant methylation was particularly enriched in kidney-specific enhancer regions associated with H3K4Me1 marks. Various important underexpressed genes, such as SMAD6, were associated with aberrantly methylated, intronic enhancers, and these changes were validated in an independent cohort. MOTIF analysis of aberrantly hypermethylated regions revealed enrichment for binding sites of AP2a, AHR, HAIRY, ARNT, and HIF1 transcription factors, reflecting contributions of dysregulated hypoxia signaling pathways in RCC. The functional importance of this aberrant hypermethylation was demonstrated by selective sensitivity of RCC cells to low levels of decitabine. Most importantly, methylation of enhancers was predictive of adverse prognosis in 405 cases of RCC in multivariate analysis. In addition, parallel copy-number analysis from MspI representations demonstrated novel copy-number variations that were validated in an independent cohort of patients.

Conclusions: Our study is the first high-resolution methylome analysis of RCC, demonstrates that many kidney-specific enhancers are targeted by aberrant hypermethylation, and reveals the prognostic importance of these epigenetic changes in an independent cohort. Clin Cancer Res; 20(16); 4349–60. ©2014 AACR.

Purpose: Recurrence risk assessment to make treatment decisions for early-stage colon cancer patients is a major unmet medical need. The aim of this retrospective multicenter study was to evaluate the clinical utility of guanylyl cyclase C (GCC) mRNA levels in lymph nodes on colon cancer recurrence.

Methods: The proportion of lymph nodes with GCC-positive mRNA (LNR) was evaluated in 463 untreated T3N0 patients, blinded to clinical outcomes. One site's (n = 97) tissue grossing method precluded appropriate lymph node assessment resulting in post hoc exclusion. Cox regression models tested the relationship between GCC and the primary endpoint of time to recurrence. Assay methods, primary analyses, and cut points were all prespecified.

Results: Final dataset contained 366 patients, 38 (10%) of whom had recurrence. Presence of four or more GCC-positive lymph nodes was significantly associated with risk of recurrence [hazard ratio (HR) = 2.46, 95% confidence interval (CI), 1.07–5.69, P = 0.035], whereas binary GCC LNR risk class (HR = 1.87, 95% CI, 0.99–3.54, P = 0.054) and mismatch repair (MMR) status (HR = 0.77, 95% CI, 0.36–1.62, P = 0.49) were not. In a secondary analysis using a 3-level GCC LNR risk group classification of high (LNR > 0.20), intermediate (0.10 < LNR ≤ 0.20), and low (LNR ≤ 0.10), high-risk patients had a 2.5 times higher recurrence risk compared with low-risk patients (HR = 2.53, 95% CI, 1.24–5.17, P = 0.011).

Conclusions: GCC status is a promising prognostic factor independent of traditional histopathology risk factors in a contemporary population of patients with stage IIa colon cancer not treated with adjuvant therapy, but GCC determination must be performed with methodology adapted to the tissue procurement and fixation technique. Clin Cancer Res; 20(16); 4361–9. ©2014 AACR.

Purpose: Krüppel-like factor 4 (KLF4) is a transcription factor and putative tumor suppressor. However, little is known about its effect on aerobic glycolysis in pancreatic tumors. Therefore, we investigated the clinical significance, biologic effects, and mechanisms of dysregulated KLF4 signaling in aerobic glycolysis in pancreatic cancer cells.

Experimental Design: Expression of KLF4 and lactate dehydrogenase A (LDHA) in 70 primary pancreatic tumors and 10 normal pancreatic tissue specimens was measured. Also, the underlying mechanisms of altered KLF4 expression and its impact on aerobic glycolysis in pancreatic cancer cells were investigated.

Results: We found a negative correlation between KLF4 and LDHA expression in pancreatic cancer cells and tissues and that their expression was associated with clinicopathologic features of pancreatic cancer. KLF4 underexpression and LDHA overexpression were correlated with disease stage and tumor differentiation. Experimentally, KLF4 overexpression significantly attenuated the aerobic glycolysis in and growth of pancreatic cancer cells both in vitro and in orthotopic mouse models, whereas knockdown of KLF4 expression had the opposite effect. Enforced KLF4 expression decreased LDHA expression, whereas small interfering RNA–mediated knockdown of KLF4 expression had the opposite effect. Mechanistically, KLF4 bound directly to the promoter regions of the LDHA gene and negatively regulated its transcription activity.

Conclusions: Dysregulated signaling in this novel KLF4/LDHA pathway significantly impacts aerobic glycolysis in and development and progression of pancreatic cancer. Clin Cancer Res; 20(16); 4370–80. ©2014 AACR.

Purpose: Management guidelines for pancreatic intraductal papillary mucinous neoplasms (IPMN) and mucinous cystic neoplasms (MCN) are based on the assumption that mucinous cysts can be accurately distinguished from other pancreatic cystic lesions. Previous studies using surgical material have identified recurrent mutations in GNAS and KRAS in pancreatic mucinous neoplasms. Yet, the diagnostic utility of testing for both genes in pancreatic cyst fluid obtained by endoscopic ultrasound–fine-needle aspiration (EUS–FNA) remains unclear.

Experimental Design: GNAS and KRAS testing was performed on EUS–FNA pancreatic cyst fluid from 91 pancreatic cysts: 41 IPMNs, 9 IPMNs with adenocarcinoma, 16 MCNs, 10 cystic pancreatic neuroendocrine tumors (PanNET), 9 serous cystadenomas (SCA), 3 retention cysts, 2 pseudocysts, and 1 lymphoepithelial cyst.

Results: Mutations in GNAS were detected in 16 (39%) IPMNs and 2 (22%) IPMNs with adenocarcinoma. KRAS mutations were identified in 28 (68%) IPMNs, 7 (78%) IPMNs with adenocarcinoma, and 1 (6%) MCN. Mutations in either gene were present in 34 (83%) IPMNs, 8 (89%) IPMNs with adenocarcinoma, and 1 (6%) MCN. No mutations were found in cystic PanNETs, SCAs, retention cysts, pseudocysts, and a lymphoepithelial cyst. GNAS and KRAS mutations had 100% specificity [95% confidence interval (CI), 0.83–1.00] but 65% sensitivity (95% CI, 0.52–0.76) for mucinous differentiation. Among IPMNs, mutations in either gene had 98% specificity (95% CI, 0.86–1.00) and 84% sensitivity (95% CI, 0.70–0.92).

Conclusions: The combination of GNAS and KRAS testing was highly specific and sensitive for IPMNs; however, the lack of sensitivity for MCNs highlights the need for additional markers to improve the detection of pancreatic mucinous neoplasms. Clin Cancer Res; 20(16); 4381–9. ©2014 AACR.

Purpose: We initially observed that the presence of circulating NY-ESO-1– and/or Melan-A–specific T cells in patients with stage IV melanoma was significantly associated with prolonged survival. Here, we report the ways in which the phenotypes and functions of these T cells differentially affect survival in patients preselected for NY-ESO-1 and/or Melan-A reactivity.

Experimental Design: We assayed functional antigen-reactive T cells recognizing NY-ESO-1 and/or Melan-A after in vitro stimulation using overlapping peptide pools. After restimulation, we assayed six cytokines simultaneously by intracellular cytokine staining. This allowed us to analyze the functional antigen response of both CD4+ and CD8+ T cells at the single-cell level.

Results: We observed that NY-ESO-1 stimulated mainly CD4+ T cells, whereas Melan-A more often stimulated CD8+ T cells. NY-ESO-1 reactivity was not associated with an additional impact on survival, whether CD4+ T cells, CD8+ T cells, or both types of T cells were responding. In contrast, recognition of Melan-A by CD4+ T cells was associated with reduced survival in our cohort of patients preselected for NY-ESO-1 and/or Melan-A reactivity (that is, in patients with exceptionally long survival). We further observed a negative effect on survival in patients with CD4+ T cells producing IL4 and IL17 upon Melan-A stimulation. Their prognosis was comparable to patients without any Melan-A reactivity.

Conclusions: The nature and prognostic impact of specific T-cell responses is different according to targeted antigen. Independent from phenotype and functional aspects, NY-ESO-1 reactivity is associated with good prognosis. In terms of Melan-A, antigen-specific CD8+ but not CD4+ responses are associated with prolonged survival. Clin Cancer Res; 20(16); 4390–9. ©2014 AACR.

Purpose: Neuroblastoma is an embryonic childhood cancer with high mortality. 13-cis retinoic acid (13-cisRA) improves survival for some patients, but many recur, suggesting clinical resistance. The mechanism of resistance and the normal differentiation pathway are poorly understood. Three–amino-acid loop extension (TALE) family genes are master regulators of differentiation. Because retinoids promote differentiation in neuroblastoma, we evaluated TALE family gene expression in neuroblastoma.

Experimental Design: We evaluated expression of TALE family genes in RA-sensitive and -resistant neuroblastoma cell lines, with and without 13-cisRA treatment, identifying genes whose expression correlates with retinoid sensitivity. We evaluated the roles of one gene, PBX1, in neuroblastoma cell lines, including proliferation and differentiation. We evaluated PBX1 expression in primary human neuroblastoma samples by qRT-PCR, and three independent clinical cohort microarray datasets.

Results: We confirmed that induction of PBX1 expression, and no other TALE family genes, was associated with 13-cisRA responsiveness in neuroblastoma cell lines. Exogenous PBX1 expression in neuroblastoma cell lines, mimicking induced PBX1 expression, significantly impaired proliferation and anchorage-independent growth, and promoted RA-dependent and -independent differentiation. Reduced PBX1 protein levels produced an aggressive growth phenotype and RA resistance. PBX1 expression correlated with histologic neuroblastoma subtypes, with highest expression in benign ganglioneuromas and lowest in high-risk neuroblastomas. High PBX1 expression is prognostic of survival, including in multivariate analysis, in the three clinical cohorts.

Conclusions: PBX1 is an essential regulator of differentiation in neuroblastoma and potentiates retinoid-induced differentiation. Neuroblastoma cells and tumors with low PBX1 expression have an immature phenotype with poorer prognosis, independent of other risk factors. Clin Cancer Res; 20(16); 4400–12. ©2014 AACR.