Pembrolizumab plus Chemotherapy in Metastatic Non-Small-Cell Lung Cancer.

BACKGROUND: First-line therapy for advanced non-small-cell lung cancer (NSCLC) that lacks targetable mutations is platinum-based chemotherapy. Among patients with a tumor proportion score for programmed death ligand 1 (PD-L1) of 50% or greater, pembrolizumab has replaced cytotoxic chemotherapy as the first-line treatment of choice. The addition of pembrolizumab to chemotherapy resulted in significantly higher rates of response and longer progression-free survival than chemotherapy alone in a phase 2 trial. METHODS: In this double-blind, phase 3 trial, we randomly assigned (in a 2:1 ratio) 616 patients with metastatic nonsquamous NSCLC without sensitizing EGFR or ALK mutations who had received no previous treatment for metastatic disease to receive pemetrexed and a platinum-based drug plus either 200 mg of pembrolizumab or placebo every 3 weeks for 4 cycles, followed by pembrolizumab or placebo for up to a total of 35 cycles plus pemetrexed maintenance therapy. Crossover to pembrolizumab monotherapy was permitted among the patients in the placebo-combination group who had verified disease progression. The primary end points were overall survival and progression-free survival, as assessed by blinded, independent central radiologic review. RESULTS: After a median follow-up of 10.5 months, the estimated rate of overall survival at 12 months was 69.2% (95% confidence interval [CI], 64.1 to 73.8) in the pembrolizumab-combination group versus 49.4% (95% CI, 42.1 to 56.2) in the placebo-combination group (hazard ratio for death, 0.49; 95% CI, 0.38 to 0.64; P<0.001). Improvement in overall survival was seen across all PD-L1 categories that were evaluated. Median progression-free survival was 8.8 months (95% CI, 7.6 to 9.2) in the pembrolizumab-combination group and 4.9 months (95% CI, 4.7 to 5.5) in the placebo-combination group (hazard ratio for disease progression or death, 0.52; 95% CI, 0.43 to 0.64; P<0.001). Adverse events of grade 3 or higher occurred in 67.2% of the patients in the pembrolizumab-combination group and in 65.8% of those in the placebo-combination group. CONCLUSIONS: In patients with previously untreated metastatic nonsquamous NSCLC without EGFR or ALK mutations, the addition of pembrolizumab to standard chemotherapy of pemetrexed and a platinum-based drug resulted in significantly longer overall survival and progression-free survival than chemotherapy alone. (Funded by Merck; KEYNOTE-189 ClinicalTrials.gov number, NCT02578680 .).

Immunogenicity and safety of the adjuvanted recombinant zoster vaccine in patients with solid tumors, vaccinated before or during chemotherapy: A randomized trial.

BACKGROUND: The adjuvanted recombinant zoster vaccine (RZV) has demonstrated >90% efficacy against herpes zoster in adults ≥50 years of age and 68% efficacy in autologous hematopoietic stem cell transplant recipients ≥18 years of age. We report the immunogenicity and safety of RZV administered to patients with solid tumors (STs) before or at the start of a chemotherapy cycle. METHOD: In this phase 2/3 observer-blind, multicenter study (NCT01798056), patients with STs who were ≥18 years of age were randomized (1:1) to receive 2 doses of RZV or placebo 1-2 months apart and stratified (4:1) according to the timing of the first dose with respect to the start of a chemotherapy cycle (first vaccination 8-30 days before the start or at the start [±1 day] of a chemotherapy cycle). Anti-glycoprotein E (gE) antibody concentrations, gE-specific CD4+ T cell frequencies, and vaccine response rates (VRRs) were assessed 1 month after dose 1 and 1 and 12 months after dose 2. Reactogenicity and safety were assessed in the total vaccinated cohort through 12 months after dose 2. RESULTS: There were 232 participants in the total vaccinated cohort, 185 participants in the according-to-protocol cohort for humoral immunogenicity, and 58 participants in the according-to-protocol cohort for cell-mediated immunogenicity. Postvaccination anti-gE antibody concentrations, gE-specific CD4+ T cell frequencies and VRRs were higher in RZV recipients than in placebo recipients. Solicited adverse events (AEs) were more frequent among RZV recipients than placebo recipients. Incidence of unsolicited AEs, serious AEs, fatalities, and potential immune-mediated diseases were similar between RZV and placebo recipients. CONCLUSION: RZV was immunogenic in patients with STs receiving immunosuppressive chemotherapies. Humoral and cell-mediated immune responses persisted 1 year after vaccination. No safety concerns were identified.

The ALK translocation in advanced non-small-cell lung carcinomas: preapproval testing experience at a single cancer centre.

AIMS: To study the ALK translocation in patients with advanced non-small-cell lung carcinomas (NSCLCs) seen at a European cancer centre, and its association with EGFR mutations, KRAS mutations and MET amplification. METHODS AND RESULTS: The study included samples from 86 patients diagnosed with advanced NSCLC. ALK fluorescence in-situ hybridization (FISH) was performed using the ALK break-apart probe set (Vysis). ALK FISH-positive cases were defined as those with more than 15% break-apart signals or isolated red signals in 50 cells. EGFR and KRAS mutations were determined by direct sequencing. All ALK-positive cases were analysed retrospectively for MET amplification using a FISH assay, and for ALK mutations by sequencing. We found nine (10.5%) ALK-positive cases, all in adenocarcinomas and the majority in female patients (88.9%). Signet ring cells were observed in four (44.4%) of the nine patients. None of the ALK translocated cases showed MET amplifications or EGFR, KRAS and ALK mutations. CONCLUSIONS: The prevalence of ALK translocation in an unselected population of European patients with advanced NSCLCs was 10%. This alteration was mutually exclusive with EGFR and KRAS mutations, as well as with MET amplification. If multiplexing is considered at the preanalytical phase, lung biopsy specimens are sufficient for performing several predictive assays.

Inhibition of ataxia telangiectasia- and Rad3-related function abrogates the in vitro and in vivo tumorigenicity of human colon cancer cells through depletion of the CD133(+) tumor-initiating cell fraction.

The identification of novel approaches to specifically target the DNA-damage checkpoint response in chemotherapy-resistant cancer stem cells (CSC) of solid tumors has recently attracted great interest. We show here in colon cancer cell lines and primary colon cancer cells that inhibition of checkpoint-modulating phosphoinositide 3-kinase-related (PIK) kinases preferentially depletes the chemoresistant and exclusively tumorigenic CD133(+) cell fraction. We observed a time- and dose-dependent disproportionally pronounced loss of CD133(+) cells and the consecutive lack of in vitro and in vivo tumorigenicity of the remaining cells. Depletion of CD133(+) cells was initiated through apoptosis of cycling CD133(+) cells and further substantiated through subsequent recruitment of quiescent CD133(+) cells into the cell cycle followed by their elimination. Models using specific PIK kinase inhibitors, somatic cell gene targeting, and RNA interference demonstrated that the observed detrimental effects of caffeine on CSC were attributable specifically to the inhibition of the PIK kinase ataxia telangiectasia- and Rad3-related (ATR). Mechanistically, phosphorylation of CHK1 checkpoint homolog (S. pombe; CHK1) was significantly enhanced in CD133(+) as compared with CD133(-) cells on treatment with DNA interstrand-crosslinking (ICL) agents, indicating a preferential activation of the ATR/CHK1-dependent DNA-damage response in tumorigenic CD133(+) cells. Consistently, the chemoresistance of CD133(+) cells toward DNA ICL agents was overcome through inhibition of ATR/CHK1-signaling. In conclusion, our study illustrates a novel target to eliminate the tumorigenic CD133(+) cell population in colon cancer and provides another rationale for the development of specific ATR-inhibitors.

Final results from TAIL: updated long-term efficacy of atezolizumab in a diverse population of patients with previously treated advanced non-small cell lung cancer.

In patients with previously treated advanced or metastatic non-small cell lung cancer (NSCLC), atezolizumab therapy improves survival with manageable safety. The open-label, single-arm phase III/IV TAIL study (NCT03285763) evaluated atezolizumab monotherapy in patients with previously treated NSCLC, including those with Eastern Cooperative Oncology Group performance status of 2, severe renal impairment, prior anti-programmed death 1 therapy, autoimmune disease, and age ≥75 years. Patients received atezolizumab intravenously (1200 mg) every 3 weeks. At data cut-off for final analysis, the median follow-up was 36.1 (range 0.0-42.3) months. Treatment-related (TR) serious adverse events (SAEs) and TR immune-related adverse events (irAEs) were the coprimary endpoints. Secondary endpoints included overall survival (OS), progression-free survival (PFS), overall response rate, and duration of response. Safety and efficacy in key patient subgroups were also assessed. TR SAEs and TR irAEs occurred in 8.0% and 9.4% of patients, respectively. No new safety signals were documented. In the overall population, median OS and PFS (95% CI) were 11.2 months (8.9 to 12.7) and 2.7 months (2.3 to 2.8), respectively. TAIL showed that atezolizumab has a similar risk-benefit profile in clinically diverse patients with previously treated NSCLC, which may guide treatment decisions for patients generally excluded from pivotal clinical trials.

PD-L1 testing and clinical management of newly diagnosed metastatic non-small cell lung cancer in Spain: MOREL study.

AIM: To describe the clinical management and PD-L1 testing of patients with newly diagnosed stage IV non-small cell lung cancer (NSCLC) without driver mutations in Spain. METHODS: Multicenter, retrospective study. RESULTS: Among 297 evaluated patients, 89.2% received systemic treatment for stage IV disease, of whom 53.6% received platinum doublet therapy, 26.8% immunotherapy as monotherapy and 14.7% immunotherapy + chemotherapy, with 9.4% receiving treatment as part of a clinical trial. Treatment was initiated 1 month after histological diagnosis, with PD-L1 test results available in most cases (92.6%). PD-L1 testing was performed in 287 patients, 95.1% by in-house tests, mostly with the 22C3 pharmDx assay. The factor most strongly associated with treatment selection was, as expected, the expression of PD-L1. CONCLUSION: PD-L1 testing is implemented in clinical practice and seems to guide treatment decisions in patients with NSCLC in Spain.

Primary results from TAIL: a global single-arm safety study of atezolizumab monotherapy in a diverse population of patients with previously treated advanced non-small cell lung cancer.

BACKGROUND: Atezolizumab treatment improves survival, with manageable safety, in patients with previously treated advanced/metastatic non-small cell lung cancer. The global phase III/IV study TAIL (NCT03285763) was conducted to evaluate the safety and efficacy of atezolizumab monotherapy in a clinically diverse population of patients with previously treated non-small cell lung cancer, including those not eligible for pivotal trials. METHODS: Patients with stage IIIB/IV non-small cell lung cancer whose disease progressed after 1-2 lines of chemotherapy were eligible for this open-label, single-arm, multicenter study, including those with severe renal impairment, an Eastern Cooperative Oncology Group performance status of 2, prior anti-programmed death 1 (PD-1) therapy, and autoimmune disease. Atezolizumab was administered intravenously (1200 mg every 3 weeks). Coprimary endpoints were treatment-related serious adverse events and immune-related adverse events. RESULTS: 619 patients enrolled and 615 received atezolizumab. At data cutoff, the median follow-up was 12.6 months (95% CI 11.9 to 13.1). Treatment-related serious adverse events occurred in 7.8% and immune-related adverse events in 8.3% of all patients and as follows, respectively, in these subgroups: renal impairment (n=78), 11.5% and 12.8%; Eastern Cooperative Oncology Group performance status of 2 (n=61), 14.8% and 8.2%; prior anti-PD-1 therapy (n=39), 5.1% and 7.7%; and autoimmune disease (n=30), 6.7% and 10.0%. No new safety signals were reported. In the overall population, the median overall survival was 11.1 months (95% CI 8.9 to 12.9), the median progression-free survival was 2.7 months (95% CI 2.1 to 2.8) and the objective response rate was 11%. CONCLUSIONS: This study confirmed the benefit-risk profile of atezolizumab monotherapy in a clinically diverse population of patients with previously treated non-small cell lung cancer. These safety and efficacy outcomes may inform treatment decisions for patients generally excluded from checkpoint inhibitor trials.

Combined targeted treatment to eliminate tumorigenic cancer stem cells in human pancreatic cancer.

BACKGROUND & AIMS: Pancreatic cancers contain exclusively tumorigenic cancer stem cells (CSCs), which are highly resistant to chemotherapy, resulting in a relative increase in CSC numbers during gemcitabine treatment. Signaling through sonic hedgehog and mammalian target of rapamycin (mTOR), respectively, may be essential for CSC self-renewal and could represent putative targets for novel treatment modalities. METHODS: We used in vitro and in vivo models of pancreatic cancer to examine the effects of sonic hedgehog inhibition (cyclopamine/CUR199691) and mTOR blockade (rapamycin) on the tumorigenic CSC population. RESULTS: Surprisingly, neither cyclopamine nor rapamycin alone or as supplements to chemotherapy were capable of effectively diminishing the CSC pool. Only the combined inhibition of both pathways together with chemotherapy reduced the number of CSCs to virtually undetectable levels in vitro and in vivo. Most importantly, in vivo administration of this triple combination in mice with established patient-derived pancreatic tumors was reasonably tolerated and translated into significantly prolonged long-term survival. CONCLUSIONS: The combined blockade of sonic hedgehog and mTOR signaling together with standard chemotherapy is capable of eliminating pancreatic CSCs. Further preclinical investigation of this promising approach may lead to the development of a novel therapeutic strategy to improve the devastating prognosis of patients with pancreatic cancer.

A direct pancreatic cancer xenograft model as a platform for cancer stem cell therapeutic development.

There is an enormous gap between the antiproliferative and in vivo antitumor efficacy of gemcitabine in cell line-based models and its clinical efficacy. This may be due to insensitiveness of the precursor, cancer stem cell (CSC) compartment to cytotoxic agents. The hedgehog pathway is associated with CSC signaling and control. We used a direct xenograft model of pancreatic cancer and a two-stage approach was used to test the hypotheses that targeting CSC could increase the efficacy of gemcitabine. Tumors from a gemcitabine-sensitive xenograft were treated with gemcitabine first, and randomized, after tumor regression to continuing treatment with gemcitabine, a hedgehog inhibitor alone or in combination with gemcitabine. We tested markers described as associated with CSC such as CD24, CD44, ALDH, nestin, and the hedgehog pathway. After induction with gemcitabine, treated tumor showed an enrichment in CSC markers such as ALDH and CD24. Subsequently, a release from gemcitabine prompted a repopulation of proliferating cells and a decrease in such markers to equilibrate from pretreatment levels. Combined treatment with gemcitabine and cyclopamine induced tumor regression and decrease in CSC markers and hedgehog signaling. Cytoplasmic CD24 and ALDH were inversely and strongly associated with growth and were expressed in a minority of cells that we propose constitute the CSC compartment. Hedgehog inhibitors as part of a dual compartment therapeutic approach were able to further reduce tumor growth and decreased both static and dynamic markers of CSC. Direct tumor xenografts are a valid platform to test multicompartment therapeutic approaches in pancreatic cancer.

Intratumoral nanoplexed poly I:C BO-112 in combination with systemic anti-PD-1 for patients with anti-PD-1-refractory tumors.

Intratumoral therapies, especially Toll-like receptor agonists, can trigger both the innate and adaptive immune systems. BO-112 is a nanoplexed form of polyinosinic:polycytidylic acid (poly I:C) that induces local and systemic immunotherapeutic effects in mouse models. In a multicenter phase 1 clinical trial, repeated intratumoral administrations of BO-112 induced an increase in tumor cell necrosis and apoptosis, as well as augmented immune reactivity according to gene expression profiling. The first three cohorts receiving BO-112 as a monotherapy resulted in a recommended dose of 1 mg that could be safely repeated. Two grade 3 to 4 adverse reactions in the form of reversible thrombocytopenia were reported. In a fourth cohort of 28 patients with tumors that had primary resistance to anti-programmed cell death protein-1 (PD-1), the combination of intratumoral BO-112 with nivolumab or pembrolizumab was also well tolerated, and 3 patients (2 with melanoma and 1 with renal cell carcinoma) achieved partial responses, with 10 more patients having stable disease at 8 to 12 weeks. Thus, local BO-112 combined with a systemic anti-PD-1 agent might be a strategy to revert anti-PD-1 resistance.

Updated Analysis From KEYNOTE-189: Pembrolizumab or Placebo Plus Pemetrexed and Platinum for Previously Untreated Metastatic Nonsquamous Non-Small-Cell Lung Cancer.

PURPOSE: In KEYNOTE-189, first-line pembrolizumab plus pemetrexed-platinum significantly improved overall survival (OS) and progression-free survival (PFS) compared with placebo plus pemetrexed-platinum in patients with metastatic nonsquamous non‒small-cell lung cancer (NSCLC), irrespective of tumor programmed death-ligand 1 (PD-L1) expression. We report an updated analysis from KEYNOTE-189 (ClinicalTrials.gov: NCT02578680). METHODS: Patients were randomly assigned (2:1) to receive pemetrexed and platinum plus pembrolizumab (n = 410) or placebo (n = 206) every 3 weeks for 4 cycles, then pemetrexed maintenance plus pembrolizumab or placebo for up to a total of 35 cycles. Eligible patients with disease progression in the placebo-combination group could cross over to pembrolizumab monotherapy. Response was assessed per RECIST (version 1.1) by central review. No alpha was assigned to this updated analysis. RESULTS: As of September 21, 2018 (median follow-up, 23.1 months), the updated median (95% CI) OS was 22.0 (19.5 to 25.2) months in the pembrolizumab-combination group versus 10.7 (8.7 to 13.6) months in the placebo-combination group (hazard ratio [HR], 0.56; 95% CI, 0.45 to 0.70]). Median (95% CI) PFS was 9.0 (8.1 to 9.9) months and 4.9 (4.7 to 5.5) months, respectively (HR, 0.48; 95% CI, 0.40 to 0.58). Median (95% CI) time from randomization to objective tumor progression on next-line treatment or death from any cause, whichever occurred first (progression-free-survival-2; PFS-2) was 17.0 (15.1 to 19.4) months and 9.0 (7.6 to 10.4) months, respectively (HR, 0.49; 95% CI, 0.40 to 0.59). OS and PFS benefits with pembrolizumab were observed regardless of PD-L1 expression or presence of liver/brain metastases. Incidence of grade 3-5 adverse events was similar in the pembrolizumab-combination (71.9%) and placebo-combination (66.8%) groups. CONCLUSION: First-line pembrolizumab plus pemetrexed-platinum continued to demonstrate substantially improved OS and PFS in metastatic nonsquamous NSCLC, regardless of PD-L1 expression or liver/brain metastases, with manageable safety and tolerability.

Management of oligometastatic non-small cell lung cancer patients: Current controversies and future directions.

Oligometastatic non-small cell lung cancer (NSCLC) describes an intermediate stage of NSCLC between localized and widely-disseminated disease. This stage of NSCLC is characterized by a limited number of metastases and a more indolent tumor biology. Currently, the management of oligometastatic NSCLC involves radical treatment (radiotherapy or surgery) that targets the metastatic lesions and the primary tumor to achieve disease control. This approach offers the potential to achieve prolonged survival in patients who, in the past, would have only received palliative measures. The optimal therapeutic strategies for the different scenarios of oligometastatic disease (intracranial vs extracranial disease, synchronous vs metachronous) remain undefined. Given the lack of head-to-head studies comparing radiotherapy to surgery in these patients, the decision to apply surgery or radiotherapy (with or without systemic treatment) must be based on prognostic factors that allow us to classify patients. This classification will allow us to select the most appropriate therapeutic strategy on an individualized basis. In the future, the molecular or microRNA profiles will likely improve the treatment selection process. The objective of the present article is to review the most relevant scientific evidence on the management of patients with oligometastatic NSCLC, focusing on the role of radiotherapy and surgery. We also discuss areas of controversy and future directions.

New scaffolds for the design of selective estrogen receptor modulators.

In the present work we report the synthesis of four new ER ligands which can be used as scaffolds for the introduction of the basic side chains necessary for antiestrogenic activity. Affinities and agonist/antagonist characterization of the ligands for both ERalpha and ERbeta have been determined in a competitive radioligand assay, and in an in vitro coactivator recruitment functional assay, respectively. Molecular modelling techniques have been used in order to rationalize the experimental results. Compound is reported as a novel ERbeta-agonist/ERalpha-antagonist. Two compounds show an interesting antitumour profile towards two pancreatic cancer cell lines and have been selected for in vivo assays.

Dual mitogen-activated protein kinase and epidermal growth factor receptor inhibition in biliary and pancreatic cancer.

This study aimed to develop rational combinations of targeted agents against biliary and pancreatic cancers. To this end, we compared the global gene expression profile of biliary cancer cell lines with different degrees of sensibility to the epidermal growth factor receptor tyrosine kinase inhibitors gefitinib and erlotinib using the Affymetrix U133A microarray platform. A set of 32 genes, including genes involved in signal transduction pathways, cell cycle regulation, and angiogenesis, was highly overexpressed in resistant cells. Five of these genes encoded proteins in the Ras/Raf/mitogen-activated protein kinase (MAPK) pathway, a finding that was confirmed by Western blot and immunohistochemistry. Gefitinib failed to inhibit the MAPK pathway in resistant cell lines. Based on these data, we explored the activity of dual treatment with gefitinib in combination with CI-1040, a MAPK inhibitor. This strategy effectively resulted in inhibition of the MAPK signaling pathway and exerted antitumor effects in vitro and in vivo in tumors resistant to each of the agents alone. To further confirm these results, we tested the combined treatment in four tumor xenografts generated from patients with resected pancreatic cancer. Combined treatment was more effective than either single agent alone in this model. This study illustrates the value of global analysis of gene expression to rationally design combinations of mechanistic-based drugs. In addition, the data support the efficacy of combined epidermal growth factor receptor and MAPK inhibitors in biliary and pancreatic cancers, providing the basis to test this combination in the clinic.

Optimizing the development of targeted agents in pancreatic cancer: tumor fine-needle aspiration biopsy as a platform for novel prospective ex vivo drug sensitivity assays.

At the present time, the optimal development of molecularly targeted anticancer agents is limited by the lack of clinically applicable tools to predict drug effects. This study aimed to develop methods that might be useful in predicting the efficacy of targeted agents in a novel model system of human pancreatic cancer. A series of xenografts were established in nude mice by implanting human pancreatic cancer tissue surgically resected from cancer patients. Animals were treated with the epidermal growth factor receptor inhibitor erlotinib, the mammalian target of rapamycin inhibitor temsirolimus, or vehicle. Tumor cells were sampled by fine-needle aspiration biopsy (FNAB) before (baseline, day 0) and at the completion of 28 days of treatment. Cells obtained at baseline were exposed to erlotinib or temsirolimus in short-term cell culture conditions (ex vivo). Western blot analysis was done to determine the degree of inhibition in the phosphorylation of extracellular signal-regulated kinase 1/2 and S6-ribosomal protein (downstream effectors of epidermal growth factor receptor and mammalian target of rapamycin, respectively) ex vivo and in vivo. Five of six xenografted tumors responded to temsirolimus, whereas only one tumor responded to erlotinib. The results of the ex vivo studies correctly predicted the pharmacodynamic effect of the agents in vivo as well as their gross antitumor effects. Finally, we showed the clinical feasibility of this approach, performing ex vivo assessment of drug-target response in FNAB samples from three patients with pancreatic cancer. Cancer cells obtained by FNAB, an established minimally invasive diagnostic procedure, can be used to test ex vivo the effects of targeted anticancer agents. These effects correlate with antitumor activity in vivo and may therefore provide an important tool applicable to clinical trials. Ultimately, an approach of this nature may facilitate the further refinement of patient selection in favor of individuals with molecular profiles, predicting a greater likelihood of therapeutic benefit.

Immunohistochemical and genetic evaluation of deoxycytidine kinase in pancreatic cancer: relationship to molecular mechanisms of gemcitabine resistance and survival.

Gemcitabine is considered the standard first-line therapy for patients with advanced pancreatic cancer. More recent strategies have focused on improving the efficacy of gemcitabine by either improving the method of delivery or by combining gemcitabine with other non-cross-resistant chemotherapy agents or with small-molecule drugs. However, the clinical benefits, response rates, and duration of responses have been modest. Deoxycytidine kinase (dCK) is the rate-limiting enzyme involved in the metabolism of gemcitabine. The expression of dCK has been postulated to be correlative of gemcitabine resistance. We determined the relationship of dCK immunohistochemical protein expression and/or genetic status of dCK in a panel of human pancreatic cancer tissues and pancreatic cancer cell lines and determined the relationship of these variables to the clinical outcome of patients treated with gemcitabine. We report that dCK protein expression is expressed in the majority of pancreatic cancers analyzed (40 of 44 cases, 91%) and showed a range of labeling intensities ranging from 1+ (labeling weaker in intensity than normal lymphocytes present in same section) to 3+ (labeling greater in intensity than normal lymphocytes present in same section). When labeling intensity was compared with survival, low dCK expression (1+ labeling) was correlated with both overall survival (P < 0.009) and progression-free survival following gemcitabine treatment (P < 0.04). Low dCK labeling intensity was also significantly correlated with patient age (70.3 +/- 8.1 versus 59.8 +/- 7.4 years; P < 0.0006), suggesting that age-related methylation of the dCK gene may account in part for the observed differences. Sequencing of the entire dCK coding sequence in 17 cell lines and 9 patients' cancer tissues with disease progression while on gemcitabine did not identify any mutations, suggesting that genetic alterations of dCK are not a common mechanism of resistance to gemcitabine for this tumor type. Moreover, dCK labeling showed similar patterns and intensities of labeling among matched pretreatment and post-treatment tissues. In summary, pretreatment levels of dCK protein are most correlated with overall survival following gemcitabine treatment and are stable even after resistance to gemcitabine is clinically documented.

An in vivo platform for translational drug development in pancreatic cancer.

Effective development of targeted anticancer agents includes the definition of the optimal biological dose and biomarkers of drug activity. Currently available preclinical models are not optimal to this end. We aimed at generating a model for translational drug development using pancreatic cancer as a prototype. Resected pancreatic cancers from 14 patients were xenografted and expanded in successive groups of nude mice to develop cohorts of tumor-bearing mice suitable for drug therapy in simulated early clinical trials. The xenografted tumors maintain their fundamental genotypic features despite serial passages and recapitulate the genetic heterogeneity of pancreatic cancer. The in vivo platform is useful for integrating drug screening with biomarker discovery. Passages of tumors in successive cohorts of mice do not change their susceptibility to anticancer agents and represent a perpetual live bank, facilitating the application of new technologies that will result in the creation of an integrated stable database of tumor-drug response data and biomarkers.

Epidermal growth factor receptor dynamics influences response to epidermal growth factor receptor targeted agents.

Analysis of gene expression of cancer cell lines exposed to erlotinib, a small molecule inhibitor of the epidermal growth factor receptor (EGFR), showed a marked increase in EGFR mRNA in resistant cell lines but not in susceptible ones. Because cetuximab induces EGFR down-regulation, we explored the hypothesis that treatment with cetuximab would interfere with erlotinib-induced EGFR up-regulation and result in antitumor effects. Exposure of the resistant biliary tract cancer cell line HuCCT1 but not the susceptible A431 epidermoid cell line to erlotinib induced EGFR mRNA and protein expression. Combined treatment with cetuximab blunted the erlotinib-induced EGFR up-regulation and resulted in inhibition of cell proliferation and apoptosis in the HuCCT1 cells. Blockage of erlotinib-induced EGFR synthesis in HuCCT1 cells by small interfering RNA resulted in identical antitumor effects as cetuximab, providing mechanistic specificity. In mice xenografted with A431, HuCCT1, and the pancreatic cancer cell line Panc430, maximal growth arrest and decrease in Ki67 proliferation index were documented with combined therapy, and EGFR down-regulation was observed in cetuximab-treated tumors. These results may indicate that resistance to EGFR kinase inhibition may be, at least in part, mediated by a highly dynamic feedback loop consisting of up-regulation of the EGFR upon exposure to EGFR kinase inhibitors. Abrogation of this response by small interfering RNA-mediated EGFR mRNA down-regulation and/or by cetuximab-mediated protein clearance induced tumor arrest across several cancer models with different EGFR expression levels, suggesting that resistance and sensitivity are dynamic events where proportional decrease in the target rather than absolute content dictates outcome.

Assessment of celecoxib pharmacodynamics in pancreatic cancer.

Cyclooxygenase-2 (COX-2) inhibitors are being developed as chemopreventive and anticancer agents. This study aimed to determine the biological effect of the COX-2 inhibitor celecoxib in pancreatic cancer as an early step to the further development of the agent in this disease. Eight patients scheduled for resection of an infiltrating adenocarcinoma of the pancreas were randomized to receive celecoxib at a dose of 400 mg twice daily or placebo for 5 to 15 days before the surgery. In addition, carcinomas from nine additional patients were xenografted in nude mice, expanded, and treated with vehicle or celecoxib for 28 days. Celecoxib markedly decreased the intra-tumor levels of prostaglandin E2 in patient carcinomas and in the heterotransplanted xenografts. However, this effect did not result in inhibition of cell proliferation or microvessel density (as assessed by Ki67 and CD31 staining). In addition, a panel of markers, including bcl-2, COX-1, COX-2, and VEGF, did not change with treatment in a significant manner. Furthermore, there was no evidence of antitumor effects in the xenografted carcinomas. In summary, celecoxib efficiently inhibited the synthesis of prostaglandin E2 both in pancreatic cancer surgical specimens and in xenografted carcinomas but did not exert evident antitumor, antiproliferative, or antiangiogenic effect as a single agent. The direct pancreatic cancer xenograft model proved to be a valuable tool for drug evaluation and biological studies and showed similar results to those observed in resected pancreatic cancer specimens.

Targeting mTOR for cancer treatment.

The mammalian target of rapamycin (mTOR) is involved in the control of cellular growth and proliferation. Abnormal activation of signaling pathways both proximal and distal to this kinase occurs frequently in human cancer, suggesting that mTOR is an attractive target for antineoplastic therapies. Rapamycin and its analogs inhibit mTOR and have demonstrated potent antitumor activity in vitro and in xenograft models. Several phase I and phase II clinical studies with rapamycin-like drugs have been conducted and have demonstrated antitumor activity in various types of refractory neoplasms. To date, mTOR inhibitors have been well tolerated at a wide range of doses, making the selection of phase II trial doses-based solely on toxicity criteria difficult. Assessment of the pharmacodynamic effects in surrogate tumor tissues has been used to determine the pharmacodynamically active doses. The lack of a parallel assessment of tumor tissue effects coupled with the intrinsically high interpatient variability has limited the value of these studies. A better understanding of markers that are predictive of response to mTOR inhibitors could be used for improved patient selection in clinical trials. mTOR inhibitors are promising anticancer agents; however, further studies are required to advance these drugs into the clinic. This review will describe the mTOR pathway and highlight its role as a potential drug target. Several mTOR inhibitors that are currently undergoing clinical development, and the challenges facing the development of inhibitors of this type, will also be discussed.