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Clinical Cancer Research

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Clinical Cancer Research

Gamma delta T-cell response to cellular stress signals expressed by tumor cells makes them promising candidates for cancer immunotherapy. The proof of concept for clinical scale propagation of polyclonal T-cell lines with efficient in vitro and in vivo response against cancer is an important step in this direction. Clin Cancer Res; 20(22); 5573–5. ©2014 AACR.

Mutations in ALK are a common mechanism of acquired resistance to small molecule ALK inhibitors in ALK-rearranged lung cancer. Different mutants exhibit differential sensitivity to ALK inhibitors. Matching the mutational profile of the tumor with the appropriate ALK inhibitor is likely to be important to maximize benefit for patients. Clin Cancer Res; 20(22); 5576–8. ©2014 AACR.

Emerging evidence suggests that cytokines produced by inflammatory cells act as rheostats to link the degree of wounding and local inflammation to epithelial cell survival, proliferation, and metabolism that collectively underpin the repair response. Among these cytokines, the GP130 family, which encompasses, among others, IL6 and IL11, plays a major role in orchestrating these complex processes through the activation of the latent signal transducer and activator of transcription 3 (STAT3) in the epithelium. However, many of the molecular mechanisms that govern and ensure effective epithelial wound healing and regeneration renewal also promote tumorigenesis and the progression of established cancers. Accordingly, GP130 cytokines endow the inflammatory tumor microenvironment with a capacity to promote "cancer hallmark capabilities" of the malignant epithelium, while simultaneously suppressing the antitumor response of innate and adaptive immune cells. Here, we review some recent insights derived from genetic and therapeutic inhibition of the IL6/IL11–GP130–STAT3 signaling cascade in the context of preclinical mouse models of cancer, which are likely to have implications to other solid malignancies. Clin Cancer Res; 20(22); 5579–88. ©2014 AACR.

This edition of CCR Focus provides critical reviews of several important areas in the field, including the application of findings from genomic investigations of brain tumors to improve diagnosis, clinical trial design, and ultimately optimizing individual patient treatment. Another article is a critical review provided by experts in the field that discusses the recent clinical trials using angiogenesis inhibitors, possible explanations for the results, and how to move forward. There is a concise discussion of the application of immunotherapy to brain tumors by key investigators in this field, reflecting the potential opportunities as well as the disease-specific challenges. Finally, leading pediatric brain tumor investigators provide an overview of the field and insights about the recent seminal discoveries in two pediatric brain tumors, supporting the paradigm that laboratory investigations lead to more precise diagnosis, prognosis, and ultimately better treatment. Herein, an overview of the recent advances and challenges in the area of clinical and translational brain tumor research is provided to set the stage for the contributions that follow.

See all articles in this CCR Focus section, "Discoveries, Challenges, and Progress in Primary Brain Tumors."

Clin Cancer Res; 20(22); 5591–600. ©2014 AACR.

While the classification of diffuse gliomas has relied on the examination of morphologic features supplemented with techniques such as immunohistochemistry, there is an increasing recognition of substantial biologic diversity within morphologically defined entities. High-throughput technologies, in particular studies that integrate genome-wide data from diverse molecular platforms, increasingly identify the existence of robust and distinct glioma subtypes. While treatment advances and improvement of outcomes for patients with diffuse glioma have been modest, there may be benefit to integrate findings from biologic studies into clinical practice to enhance the precision of treatment for these diseases. Recent examples such as the identification of mutations in IDH1 and IDH2 as an early genetic event that is predominantly in lower-grade gliomas (grades 2 and 3) underscore the importance of molecular discovery leading to the ability to develop subclassifications with prognostic and potentially therapeutic implications. In contrast, glioblastoma (grade 4), the most common and aggressive glioma, typically arises without IDH mutation, supporting the need for different therapeutic approaches. Additional genomic and epigenomic signatures are generally nonoverlapping between IDH-mutant and IDH wild-type diffuse glioma, and despite comparable histopathology, IDH-mutant gliomas can be considered as biologically distinct from IDH wild-type gliomas. In this CCR Focus article, we highlight and summarize the current understanding of recent molecular findings and the relationships of these findings to clinical trials and clinical management.

See all articles in this CCR Focus section, "Discoveries, Challenges, and Progress in Primary Brain Tumors."

Clin Cancer Res; 20(22); 5601–11. ©2014 AACR.

Glioblastoma is characterized by high expression levels of proangiogenic cytokines and microvascular proliferation, highlighting the potential value of treatments targeting angiogenesis. Antiangiogenic treatment likely achieves a beneficial impact through multiple mechanisms of action. Ultimately, however, alternative proangiogenic signal transduction pathways are activated, leading to the development of resistance, even in tumors that initially respond. The identification of biomarkers or imaging parameters to predict response and to herald resistance is of high priority. Despite promising phase II clinical trial results and patient benefit in terms of clinical improvement and longer progression-free survival, an overall survival benefit has not been demonstrated in four randomized phase III trials of bevacizumab or cilengitide in newly diagnosed glioblastoma or cediranib or enzastaurin in recurrent glioblastoma. However, future studies are warranted. Predictive markers may allow appropriate patient enrichment, combination with chemotherapy may ultimately prove successful in improving overall survival, and novel agents targeting multiple proangiogenic pathways may prove effective.

See all articles in this CCR Focus section, "Discoveries, Challenges, and Progress in Primary Brain Tumors."

Clin Cancer Res; 20(22); 5612–9. ©2014 AACR.

Immunotherapy for cancer continues to gain both momentum and legitimacy as a rational mode of therapy and a vital treatment component in the emerging era of personalized medicine. Gliomas, and their most malignant form, glioblastoma, remain as a particularly devastating solid tumor for which standard treatment options proffer only modest efficacy and target specificity. Immunotherapy would seem a well-suited choice to address such deficiencies given both the modest inherent immunogenicity of gliomas and the strong desire for treatment specificity within the confines of the toxicity-averse normal brain. This review highlights the caveats and challenges to immunotherapy for primary brain tumors, as well as reviewing modalities that are currently used or are undergoing active investigation. Tumor immunosuppressive countermeasures, peculiarities of central nervous system immune access, and opportunities for rational treatment design are discussed.

See all articles in this CCR Focus section, "Discoveries, Challenges, and Progress in Primary Brain Tumors."

Clin Cancer Res; 20(22); 5620–9. ©2014 AACR.

High-throughput genomic technologies have shed light on the biologic heterogeneity of several pediatric brain tumors. The biology of the four common pediatric brain tumors—namely medulloblastoma; ependymoma; high-grade glioma (HGG), including diffuse intrinsic pontine glioma; and low-grade glioma—is highlighted in this CCR Focus article. The discovery that medulloblastoma consists of four different subgroups, namely WNT, SHH, Group 3, and Group 4, each with distinct clinical and molecular features, has affected the treatment of children with medulloblastoma. Prospective studies have documented the efficacy of SMO inhibitors in a subgroup of patients with SHH medulloblastoma. Efforts are ongoing to develop specific therapies for each of the subgroups of medulloblastoma. Similar efforts are being pursued for ependymoma, HGG, and diffuse intrinsic pontine glioma where the disease outcome for the latter two tumors has not changed over the past three decades despite several prospective clinical trials. Developing and testing targeted therapies based on this new understanding remains a major challenge to the pediatric neuro-oncology community. The focus of this review is to summarize the rapidly evolving understanding of the common pediatric brain tumors based on genome-wide analysis. These novel insights will add impetus to translating these laboratory-based discoveries to newer therapies for children diagnosed with these tumors.

See all articles in this CCR Focus section, "Discoveries, Challenges, and Progress in Primary Brain Tumors."

Clin Cancer Res; 20(22); 5630–40. ©2014 AACR.

Purpose: To evaluate safety and activity of perifosine and sorafenib combination therapy in patients with lymphoproliferative diseases.

Experimental Design: Patients with relapsed and refractory lymphoproliferative diseases received perifosine (50 mg twice daily) for 1 month. Patients achieving less than partial response (PR) after perifosine alone were administered the combination therapy [perifosine plus sorafenib (400 mg twice daily)] until progressive disease (PD) or unacceptable toxicity occurred. The pERK and pAKT in peripheral blood lymphocytes as well as serum cytokine levels were investigated as predictive biomarkers of response.

Results: Forty patients enrolled in this study. After 1 month of perifosine alone, 36 who achieved less than PR went on to combination therapy, whereas four patients with chronic lymphocytic leukemia (CLL) who achieved PR continued with perifosine alone for a median of 10 months (range, 4–21). The most common drug-related toxicities were grade 1–2 anemia (17%), thrombocytopenia (9%), diarrhea (25%), joint pain (22%), and hand–foot skin reaction (25%). Three patients experienced grade 3 pneumonitis. Eight patients (22%) achieved PR, 15 (42%) achieved stable disease, and 13 (36%) experienced PD. A 28% PR rate was recorded for 25 patients with Hodgkin lymphoma. Among all patients, median overall survival and progression-free survival were 16 and 5 months, respectively. Early reductions in pERK and pAKT significantly correlated with the probability of clinical response.

Conclusions: Perifosine and sorafenib combination therapy is feasible with manageable toxicity and demonstrates promising activity in patients with Hodgkin lymphoma. The predictive value of pERK and pAKT should be confirmed in a larger patient cohort. Clin Cancer Res; 20(22); 5641–51. ©2014 AACR.

Purpose: This phase I study was conducted to determine the dose-limiting toxicities (DLT) and maximum tolerated dose (MTD) for the combination of bortezomib and alvocidib in patients with B-cell malignancies (multiple myeloma, indolent lymphoma, Waldenstrom macroglobulinemia, and mantle cell lymphoma).

Experimental Design: Patients received bortezomib (intravenous push), followed by alvocidib (1-hour infusion), on days 1, 4, 8, and 11 of a 21-day treatment cycle. Patients experiencing responses or stable disease continued on treatment at the investigator's discretion. A standard 3+3 dose-escalation design was used to identify the MTD based on DLTs, and pharmacokinetic and pharmacodynamic studies were conducted.

Results: A total of 44 patients were enrolled, with 39 patients assessed for response. The MTD was established as 1.3 mg/m2 for bortezomib and 40 mg/m2 for alvocidib. The most common hematologic toxicities included leukopenia, lymphopenia, neutropenia, and thrombocytopenia. The most common nonhematologic toxicities included diarrhea, fatigue, and sensory neuropathy. Three complete remissions (8%) and 10 partial remissions (26%) were observed for a total response rate of 33%. Pharmacokinetic findings with the current dosing regimen were consistent with the comparable literature and the hybrid dosing regimen. Pharmacodynamic study results did not correlate with clinical responses.

Conclusions: The combination of bortezomib and alvocidib is tolerable, and an MTD has been established for this schedule. The regimen appears to be efficacious in patients with relapsed/refractory multiple myeloma or indolent non-Hodgkin lymphoma. As the nonhybrid regimen is less cumbersome than the previous hybrid dosing schedule regimen, the current schedule is recommended for successor studies. Clin Cancer Res; 20(22); 5652–62. ©2014 AACR.

Introduction: Because a dose–response relationship is characteristic of conventional chemotherapy, this concept is widely used for the development of novel cytotoxic (CTX) drugs. However, the need to reach the MTD to obtain optimal benefit with molecularly targeted agents (MTA) is controversial. In this study, we evaluated the relationship between dose and efficacy in a large cohort of phase I patients with solid tumors.

Experimental Design: We collected data on 1,182 consecutive patients treated in phase I trials in 14 European institutions in 2005–2007. Inclusion criteria were: (i) patients treated within completed single-agent studies in which a maximum-administered dose was defined and (ii) RECIST/survival data available.

Results: Seventy-two percent of patients were included in trials with MTA (N = 854) and 28% in trials with CTX (N = 328). The objective response (OR) rate was 3% and disease control at 6 months was 11%. OR for CTX was associated with higher doses (median 92% of MTD); this was not the case for MTA, where patients achieving OR received a median of 50% of MTD. For trials with MTA, patients treated at intermediate doses (40%–80%) had better survival compared with those receiving low or high doses (P = 0.038). On the contrary, there was a direct association between higher dose and better OS for CTX agents (P = 0.003).

Conclusion: Although these results support the development of novel CTX based on MTD, we found no direct relationship between higher doses and response with MTA in unselected patients. However, the longest OS was seen in patients treated with MTA at intermediate doses (40%–80% of MTD). Clin Cancer Res; 20(22); 5663–71. ©2014 AACR.

Purpose: Multiple cancers harbor genetic aberrations that impact AKT signaling. MK-2206 is a potent pan-AKT inhibitor with a maximum tolerated dose (MTD) previously established at 60 mg on alternate days (QOD). Due to a long half-life (60–80 hours), a weekly (QW) MK-2206 schedule was pursued to compare intermittent QW and continuous QOD dosing.

Experimental Design: Patients with advanced cancers were enrolled in a QW dose-escalation phase I study to investigate the safety and pharmacokinetic–pharmacodynamic profiles of tumor and platelet-rich plasma (PRP). The QOD MTD of MK-2206 was also assessed in patients with ovarian and castration-resistant prostate cancers and patients with advanced cancers undergoing multiparametric functional magnetic resonance imaging (MRI) studies, including dynamic contrast-enhanced MRI, diffusion-weighted imaging, magnetic resonance spectroscopy, and intrinsic susceptibility-weighted MRI.

Results: A total of 71 patients were enrolled; 38 patients had 60 mg MK-2206 QOD, whereas 33 received MK-2206 at 90, 135, 150, 200, 250, and 300 mg QW. The QW MK-2206 MTD was established at 200 mg following dose-limiting rash at 250 and 300 mg. QW dosing appeared to be similarly tolerated to QOD, with toxicities including rash, gastrointestinal symptoms, fatigue, and hyperglycemia. Significant AKT pathway blockade was observed with both continuous QOD and intermittent QW dosing of MK-2206 in serially obtained tumor and PRP specimens. The functional imaging studies demonstrated that complex multiparametric MRI protocols may be effectively implemented in a phase I trial.

Conclusions: Treatment with MK-2206 safely results in significant AKT pathway blockade in QOD and QW schedules. The intermittent dose of 200 mg QW is currently used in phase II MK-2206 monotherapy and combination studies (NCT00670488). Clin Cancer Res; 20(22); 5672–85. ©2014 AACR.

Purpose: The first-generation ALK tyrosine kinase inhibitor (TKI) crizotinib is a standard therapy for patients with ALK-rearranged non–small cell lung cancer (NSCLC). Several next-generation ALK-TKIs have entered the clinic and have shown promising activity in crizotinib-resistant patients. As patients still relapse even on these next-generation ALK-TKIs, we examined mechanisms of resistance to the next-generation ALK-TKI alectinib and potential strategies to overcome this resistance.

Experimental Design: We established a cell line model of alectinib resistance, and analyzed a resistant tumor specimen from a patient who had relapsed on alectinib. We developed Ba/F3 models harboring alectinib-resistant ALK mutations and evaluated the potency of other next-generation ALK-TKIs in these models. We tested the antitumor activity of the next-generation ALK-TKI ceritinib in the patient with acquired resistance to alectinib. To elucidate structure–activity relationships of ALK mutations, we performed computational thermodynamic simulation with MP-CAFEE.

Results: We identified a novel V1180L gatekeeper mutation from the cell line model and a second novel I1171T mutation from the patient who developed resistance to alectinib. Both ALK mutations conferred resistance to alectinib as well as to crizotinib, but were sensitive to ceritinib and other next-generation ALK-TKIs. Treatment of the patient with ceritinib led to a marked response. Thermodynamics simulation suggests that both mutations lead to distinct structural alterations that decrease the binding affinity with alectinib.

Conclusions: We have identified two novel ALK mutations arising after alectinib exposure that are sensitive to other next-generation ALK-TKIs. The ability of ceritinib to overcome alectinib-resistance mutations suggests a potential role for sequential therapy with multiple next-generation ALK-TKIs. Clin Cancer Res; 20(22); 5686–96. ©2014 AACR.

Purpose: Interleukin-8 (IL8) is a chemokine produced by malignant cells of multiple cancer types. It exerts various functions in shaping protumoral vascularization and inflammation/immunity. We evaluated sequential levels of serum IL8 in preclinical tumor models and in patients to assess its ability to estimate tumor burden.

Experimental Design: IL8 levels were monitored by sandwich ELISAs in cultured tumor cells supernatants, tumor-xenografted mice serum, and in samples from 126 patients with cancer. We correlated IL8 serum levels with baseline tumor burden and with treatment-induced changes in tumor burden, as well as with prognosis.

Results: IL8 concentrations correlated with the number of IL8-producing tumor cells in culture. In xenografted neoplasms, IL8 serum levels rapidly dropped after surgical excision, indicating an accurate correlation with tumor burden. In patients with melanoma (n = 16), renal cell carcinoma (RCC; n = 23), non–small cell lung cancer (NSCLC; n = 21), or hepatocellular carcinoma (HCC; n = 30), serum IL8 concentrations correlated with tumor burden and stage, survival (melanoma, n = 16; RCC, n = 23; HCC, n = 33), and objective responses to therapy, including those to BRAF inhibitors (melanoma, n = 16) and immunomodulatory monoclonal antibodies (melanoma, n = 8). IL8 concentrations in urine (n = 18) were mainly elevated in tumors with direct contact with the urinary tract.

Conclusions: IL8 levels correlate with tumor burden in preclinical models and in patients with cancer. IL8 is a potentially useful biomarker to monitor changes in tumor burden following anticancer therapy, and has prognostic significance. Clin Cancer Res; 20(22); 5697–707. ©2014 AACR.

Purpose: To activate and propagate populations of T cells expressing polyclonal repertoire of and T-cell receptor (TCR) chains for adoptive immunotherapy of cancer, which has yet to be achieved.

Experimental Design: Clinical-grade artificial antigen-presenting cells (aAPC) derived from K562 tumor cells were used as irradiated feeders to activate and expand human T cells to clinical scale. These cells were tested for proliferation, TCR expression, memory phenotype, cytokine secretion, and tumor killing.

Results: T-cell proliferation was dependent upon CD137L expression on aAPC and addition of exogenous IL2 and IL21. Propagated T cells were polyclonal as they expressed TRDV1, TRDV2-2, TRDV3, TRDV5, TRDV7, and TRDV8 with TRGV2, TRGV3F, TRGV7, TRGV8, TRGV9*A1, TRGV10*A1, and TRGV11 TCR chains. IFN production by V1, V2, and V1negV2neg subsets was inhibited by pan-TCR antibody when added to cocultures of polyclonal T cells and tumor cell lines. Polyclonal T cells killed acute and chronic leukemia, colon, pancreatic, and ovarian cancer cell lines, but not healthy autologous or allogeneic normal B cells. Blocking antibodies demonstrated that polyclonal T cells mediated tumor cell lysis through combination of DNAM1, NKG2D, and TCR. The adoptive transfer of activated and propagated T cells expressing polyclonal versus defined V TCR chains imparted a hierarchy (polyclonal>V1>V1negV2neg>V2) of survival of mice with ovarian cancer xenografts.

Conclusions: Polyclonal T cells can be activated and propagated with clinical-grade aAPCs and demonstrate broad antitumor activities, which will facilitate the implementation of T-cell cancer immunotherapies in humans. Clin Cancer Res; 20(22); 5708–19. ©2014 AACR.

Purpose: The majority of circulating human T lymphocytes are of the V9V2 lineage, and have T-cell receptor (TCR) specificity for nonpeptide phosphoantigens. Previous attempts to stimulate and expand these cells have therefore focused on stimulation using ligands of the V9V2 receptor, whereas relatively little is known about variant blood T subsets and their potential role in cancer immunotherapy.

Experimental Design: To expand the full repertoire of T without bias toward specific TCRs, we made use of artificial antigen-presenting cells loaded with an anti TCR antibody that promoted unbiased expansion of the T repertoire. Expanded cells from adult blood donors were sorted into 3 populations expressing respectively V2 TCR chains (V2+), V1 chains (V1+), and TCR of other chain subtypes (V1negV2neg).

Results: Both freshly isolated and expanded cells showed heterogeneity of differentiation markers, with a less differentiated phenotype in the V1 and V1negV2neg populations. Expanded cells were largely of an effector memory phenotype, although there were higher numbers of less differentiated cells in the V1+ and V1negV2neg populations. Using neuroblastoma tumor cells and the anti-GD2 therapeutic mAb ch14.18 as a model system, all three populations showed clinically relevant cytotoxicity. Although killing by expanded V2 cells was predominantly antibody dependent and proportionate to upregulated CD16, V1 cells killed by antibody-independent mechanisms.

Conclusions: In conclusion, we have demonstrated that polyclonal-expanded populations of T cells are capable of both antibody-dependent and -independent effector functions in neuroblastoma. Clin Cancer Res; 20(22); 5720–32. ©2014 AACR.

Purpose: Anaplastic thyroid carcinoma (ATC) is one of the most aggressive forms of cancer with no curative therapies available. To date, strategies to target ATC by immunotherapy have not been evaluated. We investigated whether ATC would be a suitable target for natural killer (NK) cell–based immunotherapy.

Experimental Design: We first established seven new cell lines from ATC tumors, three from papillary thyroid carcinoma tumors and analyzed them together with eight additional ATC cell lines. Cells were analyzed for sensitivity to lysis by NK cells and their ability to chemoattract and regulate the activity of NK cells. In addition, fresh tumor samples and peripheral blood from six patients with ATC were analyzed for NK cell infiltration and phenotype.

Results: We observed that ATC cell lines are sensitive to lysis by ex vivo expanded NK cells and that the lysis was abrogated upon blockade of NKG2D. Sensitivity of thyroid cancer cell lines to NK cell–mediated lysis correlated with surface expression of UL16-binding protein 2 on tumor cells. Moreover, ATC cell lines produced high levels of CXCL10 and stimulated migration of expanded NK cells and ATC tumors were enriched for NK cells expressing the cognate chemokine receptor CXCR3. However, compared with NK cells in peripheral blood, ATC tumor–derived NK cells displayed a suppressed phenotype with a downregulated expression of NKG2D. In vitro, suppression of NK cell–mediated lysis and NKG2D expression by ATC cells was restored upon neutralization of prostaglandin-E2.

Conclusions: ATC cell lines are sensitive to NK cell–mediated lysis via ULBP2/5/6 and chemoattract CXCR3-positive NK cells. Patients with ATC may benefit from NK cell–based immunotherapy. Clin Cancer Res; 20(22); 5733–44. ©2014 AACR.

Purpose: KIT is the major oncogenic driver of gastrointestinal stromal tumors (GIST). Imatinib, sunitinib, and regorafenib are approved therapies; however, efficacy is often limited by the acquisition of polyclonal secondary resistance mutations in KIT, with those located in the activation (A) loop (exons 17/18) being particularly problematic. Here, we explore the KIT-inhibitory activity of ponatinib in preclinical models and describe initial characterization of its activity in patients with GIST.

Experimental Design: The cellular and in vivo activities of ponatinib, imatinib, sunitinib, and regorafenib against mutant KIT were evaluated using an accelerated mutagenesis assay and a panel of engineered and GIST-derived cell lines. The ponatinib–KIT costructure was also determined. The clinical activity of ponatinib was examined in three patients with GIST previously treated with all three FDA-approved agents.

Results: In engineered and GIST-derived cell lines, ponatinib potently inhibited KIT exon 11 primary mutants and a range of secondary mutants, including those within the A-loop. Ponatinib also induced regression in engineered and GIST-derived tumor models containing these secondary mutations. In a mutagenesis screen, 40 nmol/L ponatinib was sufficient to suppress outgrowth of all secondary mutants except V654A, which was suppressed at 80 nmol/L. This inhibitory profile could be rationalized on the basis of structural analyses. Ponatinib (30 mg daily) displayed encouraging clinical activity in two of three patients with GIST.

Conclusion:Ponatinib possesses potent activity against most major clinically relevant KIT mutants and has demonstrated preliminary evidence of activity in patients with refractory GIST. These data strongly support further evaluation of ponatinib in patients with GIST. Clin Cancer Res; 20(22); 5745–55. ©2014 AACR.

Purpose: The EGFR and PI3K/mTORC1/2 pathways are frequently altered in glioblastoma (GBM), but pharmacologic targeting of EGFR and PI3K signaling has failed to demonstrate efficacy in clinical trials. Lack of relevant models has rendered it difficult to assess whether targeting these pathways might be effective in molecularly defined subgroups of GBMs. Here, human brain tumor–initiating cell (BTIC) lines with different combinations of endogenous EGFR wild-type, EGFRvIII, and PTEN mutations were used to investigate response to the EGFR inhibitor gefitinib, mTORC1 inhibitor rapamycin, and dual mTORC1/2 inhibitor AZD8055 alone and in combination with temozolomide (TMZ)

Experimental Design: In vitro growth inhibition and cell death induced by gefitinib, rapamycin, AZD8055, and TMZ or combinations in human BTICs were assessed by alamarBlue, neurosphere, and Western blotting assays. The in vivo efficacy of AZD8055 was assessed in subcutaneous and intracranial BTIC xenografts. Kaplan–Meier survival studies were performed with AZD8055 and in combination with TMZ.

Results: We confirm that gefitinib and rapamycin have modest effects in most BTIC lines, but AZD8055 was highly effective at inhibiting Akt/mTORC2 activity and dramatically reduced the viability of BTICs regardless of their EGFR and PTEN mutational status. Systemic administration of AZD8055 effectively inhibited tumor growth in subcutaneous BTIC xenografts and mTORC1/2 signaling in orthotopic BTIC xenografts. AZD8055 was synergistic with the alkylating agent TMZ and significantly prolonged animal survival.

Conclusion: These data suggest that dual inhibition of mTORC1/2 may be of benefit in GBM, including the subset of TMZ-resistant GBMs. Clin Cancer Res; 20(22); 5756–67. ©2014 AACR.

Purpose: Here, we aim to investigate the molecular mechanism of regorafenib and verify the potential druggable target for the treatment of hepatocellular carcinoma (HCC).

Experimental Design: HCC cell lines (PLC5, HepG2, Hep3B, SK-Hep1, and HA59T) were used to investigate the in vitro effect of regorafenib. Phosphatase activity was analyzed in HCC cells and purified SHP-1 proteins. PLC5-bearing mice were used to test the therapeutic efficiency of 20 and 40 mg/kg/d treatment with regorafenib ($n \ge 8$ mice). The clinical relevance of STAT3 signaling was investigated with 142 tumor samples from different patients with HCC. Descriptive statistical analysis was used to compare the baseline characteristics of patients and the expression of p-STAT3.

Results: Regorafenib inhibited STAT3-related signaling in a dose-dependent manner and was a more potent inhibitor of STAT3 than sorafenib. Regorafenib increased SHP-1 phosphatase activity in purified SHP-1 protein directly. N-SH2 domain deletion and D61A mutants mimicking open-form SHP-1 partially abolished regorafenib-induced STAT3 inhibition and apoptosis. Importantly, a higher level of expression of STAT3 was found in patients with advanced clinical stages (P = 0.009) and poorly differentiated tumors (P = 0.035).

Conclusions: Regorafenib induced significant tumor inhibition by relieving the autoinhibited N-SH2 domain of SHP-1 directly and inhibiting p-STAT3 signals. STAT3 may be suitable as a prognostic marker of HCC development, and may be a druggable target for HCC-targeted therapy using regorafenib. Clin Cancer Res; 20(22); 5768–76. ©2014 AACR.

Purpose: The basaloid carcinoma (pure) and the (mixed) basaloid variant of lung squamous cell carcinoma (SCC) have a dismal prognosis but their underlying specific molecular characteristics remain obscure and no therapy has proven to be efficient.

Experimental Design: To assess their molecular specificity among other lung SCCs we analyzed DNA copy number aberrations and mRNA expression pangenomic profiles of 93 SCCs, including 42 basaloid samples (24 pure, 18 mixed).

Results: Supervised analyses reveal that pure basaloid tumors display a specific mRNA expression profile, encoding factors controlling the cell cycle, transcription, chromatin, and splicing, with prevalent expression in germline and stem cells, while genes related to squamous differentiation are underexpressed. From this signature, we derived a 2-genes (SOX4, IVL) immunohistochemistry-based predictor that discriminated basaloid tumors (pure and mixed) from non-basaloid tumors with 94% accuracy in an independent series. The pure basaloid tumors are also distinguished through unsupervised analyses. Using a centroid-based predictor, the corresponding molecular subtype was found in 8 independent public datasets (n = 58/533), and was shown to be associated with a very poor survival as compared with other SCCs (adjusted HR = 2.45; P = 0.000001).

Conclusion: This study enlightens the heterogeneity of SCCs that can be subclassified in mRNA expression subtypes. This study demonstrates for the first time that basaloid SCCs constitute a distinct histomolecular entity, which justifies its recognition and distinction from non-basaloid SCCs. In addition, their characteristic molecular profile highlights their intrinsic resistance to cytotoxic chemotherapy and could serve as a guide for targeted therapies. Clin Cancer Res; 20(22); 5777–86. ©2014 AACR.

Purpose: Pancreatic ductal adenocarcinoma (PDAC) is a significant cause of cancer mortality. Carbohydrate antigen 19.9 (CA19.9), the only tumor marker available to detect and monitor PDAC, is not sufficiently sensitive and specific to consistently differentiate early cancer from benign disease. In this study, we aimed to validate recently discovered serum protein biomarkers for the early detection of PDAC and ultimately develop a biomarker panel that could discriminate PDAC from other benign disease better than the existing marker CA19.9.

Patients and Methods: We performed a retrospective blinded evaluation of 400 serum samples collected from individuals recruited on a consecutive basis. The sample population consisted of 250 individuals with PDAC at various stages, 130 individuals with benign conditions and 20 healthy individuals. The serum levels of each biomarker were determined by ELISAs or automated immunoassay.

Results: By randomly splitting matched samples into a training (n = 186) and validation (n = 214) set, we were able to develop and validate a biomarker panel consisting of CA19.9, CA125, and LAMC2 that significantly improved the performance of CA19.9 alone. Improved discrimination was observed in the validation set between all PDAC and benign conditions (AUCCA19.9 = 0.80 vs. AUCCA19.9+CA125+LAMC2 = 0.87; P < 0.005) as well as between early-stage PDAC and benign conditions (AUCCA19.9 = 0.69 vs. AUCCA19.9+CA125+LAMC2 = 0.76; P < 0.05) and between early-stage PDAC and chronic pancreatitis (CP; AUCCA19.9 = 0.59 vs. AUCCA19.9+CA125+LAMC2 = 0.74; P < 0.05).

Conclusions: The data demonstrate that a serum protein biomarker panel consisting of CA125, CA19.9, and LAMC2 is able to significantly improve upon the performance of CA19.9 alone in detecting PDAC. Clin Cancer Res; 20(22); 5787–95. ©2014 AACR.

Purpose: The aim of this study was to investigate the angiogenic role of the hepatocyte growth factor (HGF)/cMET pathway and its inhibition in bone marrow endothelial cells (EC) from patients with multiple myeloma versus from patients with monoclonal gammopathy of undetermined significance (MGUS) or benign anemia (control group).

Experimental Design: The HGF/cMET pathway was evaluated in ECs from patients with multiple myeloma (multiple myeloma ECs) at diagnosis, at relapse after bortezomib- or lenalidomide-based therapies, or on refractory phase to these drugs; in ECs from patients with MGUS (MGECs); and in those patients from the control group. The effects of a selective cMET tyrosine kinase inhibitor (SU11274) on multiple myeloma ECs' angiogenic activities were studied in vitro and in vivo.

Results: Multiple myeloma ECs express more HGF, cMET, and activated cMET (phospho (p)-cMET) at both RNA and protein levels versus MGECs and control ECs. Multiple myeloma ECs are able to maintain the HGF/cMET pathway activation in absence of external stimulation, whereas treatment with anti-HGF and anti-cMET neutralizing antibodies (Ab) is able to inhibit cMET activation. The cMET pathway regulates several multiple myeloma EC activities, including chemotaxis, motility, adhesion, spreading, and whole angiogenesis. Its inhibition by SU11274 impairs these activities in a statistically significant fashion when combined with bortezomib or lenalidomide, both in vitro and in vivo.

Conclusions: An autocrine HGF/cMET loop sustains multiple myeloma angiogenesis and represents an appealing new target to potentiate the antiangiogenic management of patients with multiple myeloma. Clin Cancer Res; 20(22); 5796–807. ©2014 AACR.

Purpose: IDH1/2-mutant gliomas harbor a distinct glioma-CpG island methylation phenotype (G-CIMP) that may promote the initiation and progression of secondary pathway gliomas by silencing tumor-suppressive genes. The potential role of tumor-suppressive microRNAs (miRNA; miR) in this process is not understood.

Experimental Design: To identify potential tumor-suppressive miRNA hypermethylated in glioma, the methylation profiles of IDH1/2WT gliomas (n = 11) and IDH1MUT glioma (n = 20) were compared by using massively parallel reduced representation bisulfite sequencing (RRBS). The methylation status of selected miRNA was validated by using targeted bisulfite sequencing (BiSEQ) in a large cohort of glioma tissue samples including 219 IDH1WT and 72 IDH1/2MUT samples. The expression of selected miRNAs was determined by using the TaqMan qPCR. Functional analyses of miR148a were conducted and target genes were identified.

Results: We identify miR148a as a novel, G-CIMP–associated miRNA whose methylation is tightly correlated with IDH1 mutation and associated with improved survival in patients with malignant glioma. We confirm that downregulation of miR148a can occur via DNA methylation. We demonstrate that IDH1 mutation provides a mechanism of miR148a methylation and downregulation, and that restoration of miR148a reduced tumorigenic properties of glioma cells, possibly by targeting DNMT1.

Conclusions: We identify miR148a as a novel G-CIMP–associated miRNA, and provide results suggesting that miR148a restoration may have therapeutic implications. Clin Cancer Res; 20(22); 5808–22. ©2014 AACR.

Purpose: Molecular characterization of circulating tumor cells (CTC) is crucial for the investigation of molecular-targeted therapies while PIK3CA somatic mutations play a crucial role in therapy response. We investigated the presence of PIK3CA mutations in CTC and whether this is associated with clinical outcome.

Experimental Design: We developed and validated an ultrasensitive methodology for the detection of PIK3CA mutations that is based on a combination of allele-specific, asymmetric rapid PCR and melting analysis. We analyzed PIK3CA hotspot mutations in: (i) a training group consisting of EpCAM-positive CTC fraction from 37 patients with clinically confirmed metastasis, and 26 healthy female volunteers and 15 primary breast tumor tissues and (ii) an independent group consisting of EpCAM-positive CTC fraction from 57 metastatic and 118 operable breast cancer patients and 76 corresponding primary tumors.

Results: The assay could detect 0.05% of mutated dsDNA in the presence of 99.95% wtDNA for both exons (9 and 20) and was highly specific (0/26 healthy donors). PIK3CA mutations were identified in EpCAM-positive CTC in 20 of 57(35.1%) and in 23 of 118 (19.5%) patients with metastatic and operable breast cancer, and in 45 of 76(59.2%) corresponding FFPEs. Our data indicate that PIK3CA mutational status in CTCs can change during disease progression and is associated with worse survival (P = 0.047).

Conclusions: PIK3CA hotspot mutations are present at a relatively high frequency in CTCs and their presence is associated with worse survival in patients with breast cancer with metastasis. Evaluation of PIK3CA mutational status in CTCs is a strategy with potential clinical application. Clin Cancer Res; 20(22); 5823–34. ©2014 AACR.

Purpose: The expression of LIM and SH3 protein 1 (LASP1) was upregulated in colorectal cancer cases, thereby contributing to the aggressive phenotypes of colorectal cancer cells. However, we still cannot decipher the underlying molecular mechanism associated with colorectal cancer metastasis.

Experimental Design: In this study, IHC was performed to investigate the expression of proteins in human colorectal cancer tissues. Western blot analysis was used to assess the LASP1-induced signal pathway. Two-dimensional difference gel electrophoresis was performed to screen LASP1-modulated proteins and uncover the molecular mechanism of LASP1. TGFβ was used to induce an epithelial–mesenchymal transition (EMT).

Results: LASP1 expression was correlated with the mesenchymal marker vimentin and was inversely correlated with epithelial markers, namely, E-cadherin and β-catenin, in clinical colorectal cancer samples. The gain- and loss-of-function assay showed that LASP1 induces EMT-like phenotypes in vitro and in vivo. S100A4, identified as a LASP1-modulated protein, was upregulated by LASP1. Moreover, it is frequently coexpressed with LASP1 in colorectal cancer. S100A4 was required for EMT, and an increased cell invasiveness of colorectal cancer cell is induced by LASP1. Furthermore, the stimulation of TGFβ resulted in an activated Smad pathway that increased the expression of LASP1 and S100A4. The depletion of LASP1 or S100A4 expression inhibited the TGFβ signaling pathway. Moreover, it significantly weakened the proinvasive effects of TGFβ on colorectal cancer cells.

Conclusion: These findings elucidate the central role of LASP1 in the TGFβ-mediated EMT process and suggest a potential target for the clinical intervention in patients with advanced colorectal cancer. Clin Cancer Res; 20(22); 5835–47. ©2014 AACR.

Purpose: We previously showed that EGF receptor (EGFR) promotes tumorigenesis in the azoxymethane/dextran sulfate sodium (AOM/DSS) model, whereas vitamin D suppresses tumorigenesis. EGFR–vitamin D receptor (VDR) interactions, however, are incompletely understood. Vitamin D inhibits the renin–angiotensin system (RAS), whereas RAS can activate EGFR. We aimed to elucidate EGFR–VDR cross-talk in colorectal carcinogenesis.

Experimental Design: To examine VDR–RAS interactions, we treated Vdr+/+ and Vdr–/– mice with AOM/DSS. Effects of VDR on RAS and EGFR were examined by Western blotting, immunostaining, and real-time PCR. We also examined the effect of vitamin D3 on colonic RAS in Vdr+/+ mice. EGFR regulation of VDR was examined in hypomorphic EgfrWaved2 (Wa2) and Egfrwild-type mice. Angiotensin II (Ang II)–induced EGFR activation was studied in cell culture.

Results: Vdr deletion significantly increased tumorigenesis, activated EGFR and β-catenin signaling, and increased colonic RAS components, including renin and angiotensin II. Dietary VD3 supplementation suppressed colonic renin. Renin was increased in human colon cancers. In studies in vitro, Ang II activated EGFR and stimulated colon cancer cell proliferation by an EGFR-mediated mechanism. Ang II also activated macrophages and colonic fibroblasts. Compared with tumors from EgfrWaved2 mice, tumors from Egfrwild-type mice showed upregulated Snail1, a suppressor of VDR, and downregulated VDR.

Conclusions: VDR suppresses the colonic RAS cascade, limits EGFR signals, and inhibits colitis-associated tumorigenesis, whereas EGFR increases Snail1 and downregulates VDR in colonic tumors. Taken together, these results uncover a RAS-dependent mechanism mediating EGFR and VDR cross-talk in colon cancer. Clin Cancer Res; 20(22); 5848–59. ©2014 AACR.