Enzastaurin, an oral serine/threonine kinase inhibitor, as second- or third-line therapy of non-small-cell lung cancer

An Update on Protein Kinases as Therapeutic Targets-Part I: Protein Kinase C Activation and Its Role in Cancer and Cardiovascular Diseases

Protein kinases are one of the most significant drug targets in the human proteome, historically harnessed for the treatment of cancer, cardiovascular disease, and a growing number of other conditions, including autoimmune and inflammatory processes. Since the approval of the first kinase inhibitors in the late 1990s and early 2000s, the field has grown exponentially, comprising 98 approved therapeutics to date, 37 of which were approved between 2016 and 2021. While many of these small-molecule protein kinase inhibitors that interact orthosterically with the protein kinase ATP binding pocket have been massively successful for oncological indications, their poor selectively for protein kinase isozymes have limited them due to toxicities in their application to other disease spaces. Thus, recent attention has turned to the use of alternative allosteric binding mechanisms and improved drug platforms such as modified peptides to design protein kinase modulators with enhanced selectivity and other pharmacological properties. Herein we review the role of different protein kinase C (PKC) isoforms in cancer and cardiovascular disease, with particular attention to PKC-family inhibitors. We discuss translational examples and carefully consider the advantages and limitations of each compound (Part I). We also discuss the recent advances in the field of protein kinase modulators, leverage molecular docking to model inhibitor-kinase interactions, and propose mechanisms of action that will aid in the design of next-generation protein kinase modulators (Part II).

Protein Kinase C as a Therapeutic Target in Non-Small Cell Lung Cancer

Driver-directed therapeutics have revolutionized cancer treatment, presenting similar or better efficacy compared to traditional chemotherapy and substantially improving quality of life. Despite significant advances, targeted therapy is greatly limited by resistance acquisition, which emerges in nearly all patients receiving treatment. As a result, identifying the molecular modulators of resistance is of great interest. Recent work has implicated protein kinase C (PKC) isozymes as mediators of drug resistance in non-small cell lung cancer (NSCLC). Importantly, previous findings on PKC have implicated this family of enzymes in both tumor-promotive and tumor-suppressive biology in various tissues. Here, we review the biological role of PKC isozymes in NSCLC through extensive analysis of cell-line-based studies to better understand the rationale for PKC inhibition. PKC isoforms α, ε, η, ι, ζ upregulation has been reported in lung cancer, and overexpression correlates with worse prognosis in NSCLC patients. Most importantly, PKC isozymes have been established as mediators of resistance to tyrosine kinase inhibitors in NSCLC. Unfortunately, however, PKC-directed therapeutics have yielded unsatisfactory results, likely due to a lack of specific evaluation for PKC. To achieve satisfactory results in clinical trials, predictive biomarkers of PKC activity must be established and screened for prior to patient enrollment. Furthermore, tandem inhibition of PKC and molecular drivers may be a potential therapeutic strategy to prevent the emergence of resistance in NSCLC.

A new indolocarbazole derivative in melanoma and carcinoma lung in vivo treatment

Objective

The current scientific research direction is development of drugs with a targeted effect on malignant tumors. One of the promising groups is indolocarbazoles and their derivatives, which can initiate various tumor cell death pathways. Russian scientists from N. N. Blokhin National Medical Research Center of Oncology of the Ministry of Health of Russian Federation has developed a new experimental drug form of the original compound LCS 1269 with cytotoxic and antiangiogenic properties, blocking vasculogenic mimicry in tumor. The study aim is the experimental drug form LCS 1269 antitumor activity on models of transplantable mouse tumors B-16 melanoma and Lewis epidermoid lung carcinoma (LLC) with different routes and modes of administration.

Material and methods

Female F1 hybrid mice (C₅₇Bl/₆ x DBA/2) and male and female linear mice C₅₇BL/₆ were used for management of tumor strains. Mice were obtained from N. N. Blokhin National Medical Research Center of Oncology of the Ministry of Health of Russian Federation vivarium. The antitumor effect was assessed by tumor growth inhibition (TGI) and increase of treated animal’s life span (ILS) compared to the control.

Results

The experimental drug form showed high antitumor activity when administered intravenously once at doses of 100 and 120 mg/kg (TGI = 98–82% and TGI = 95–77%, respectively, ILS = 24%, p < 0.05) on melanoma B-16 mice. On LLC mice, the experimental drug form showed that the intravenous administration route was effective in the range of doses from 60 to 80 mg/kg with a 5 day administration regimen with an interval of 24 h. A dose of 70 mg/kg had maximum effect at the level of TGI = 96–77% (p < 0.05) with its retention for 20 days after the end of treatment.

Conclusion

The studies have shown that the new compound LCS 1269 in the original drug form, has a pronounced antitumor activity and significantly reduces the volume of tumor mass both on melanoma B-16 and on LLC. It allows us to recommend continue the search for sensitivity of animal transplantable tumors to LCS 1269.

Synthesis and Biological Evaluation of Novel 4-(4-Formamidophenylamino)-N-methylpicolinamide Derivatives as Potential Antitumor Agents

A novel series of 4-(4-formamidophenylamino)-N-methylpicolinamide derivatives were synthesized and evaluated against different tumor cell lines. Experiments in vitro showed that these derivatives could inhibit the proliferation of two kinds of human cancer cell lines (HepG2, HCT116) at low micromolar concentrations and the most potent analog 5q possessed broad-spectrum antiproliferative activity. Experiments in vivo demonstrated that 5q could effectively prolong the longevity of colon carcinoma-burdened mice and slow down the progression of cancer cells by suppression of angiogenesis and the induction of apoptosis and necrosis.

Protein kinases as targets for developing anticancer agents from marine organisms

Protein kinases play a fundamental role in the intracellular transduction because of their ability to phosphorylate plethora of proteins. Over the past three decades, numerous protein kinase inhibitors have been identified and are being used clinically successfully. The biodiversity of marine organisms provides a rich source for the discovery and development of novel anticancer agents in the treatment of human malignancies and a lot of bioactive ingredients from marine organisms display anticancer effects by affecting the protein kinases-mediated pathways. In the present mini-review, anticancer compounds from marine source were reviewed and discussed in context of their targeted pathways associated with protein kinases and the progress of these compounds as anticancer agents in recent five years were emphasized. The molecular entities and their modes of actions were presented. We focused on protein kinases-mediated signaling pathways including PI3K/Akt/mTOR, p38 MAPK, and EGFR. The marine compounds targeting special pathways of protein kinases were highlighted. We have also discussed the existing challenges and prospects related to design and development of novel protein kinase inhibitors from marine sources.

Enzastaurin: A lesson in drug development

Enzastaurin is an orally administered drug that was intended for the treatment of solid and haematological cancers. It was initially developed as an isozyme specific inhibitor of protein kinase Cβ (PKCβ), which is involved in both the AKT and MAPK signalling pathways that are active in many cancers. Enzastaurin had shown encouraging preclinical results for the prevention of angiogenesis, inhibition of proliferation and induction of apoptosis as well as showing limited cytotoxicity within phase I clinical trials. However, during its assessment in phase II and III clinical trials the efficacy of enzastaurin was poor both in combination with other drugs and as a single agent. In this review, we will discuss the development of enzastaurin from drug design to clinical testing, exploring target identification, validation and preclinical assessment. Finally, we will consider the clinical evaluation of enzastaurin as an example of the challenges associated with drug development. In particular, we discuss the poor translation of drug efficacy from preclinical animal models, inappropriate end point analysis, limited standards in phase I clinical trials, insufficient use of biomarker analysis and also patient stratification, all of which contributed to the failure to achieve approval of enzastaurin as an anticancer therapeutic.

Enzastaurin inhibits ABCB1-mediated drug efflux independently of effects on protein kinase C signalling and the cellular p53 status

The PKCβ inhibitor enzastaurin was tested in parental neuroblastoma and rhabdomyosarcoma cell lines, their vincristine-resistant sub-lines, primary neuroblastoma cells, ABCB1-transduced, ABCG2-transduced, and p53-depleted cells. Enzastaurin IC₅₀s ranged from 3.3 to 9.5 μM in cell lines and primary cells independently of the ABCB1, ABCG2, or p53 status. Enzastaurin 0.3125 μM interfered with ABCB1-mediated drug transport. PKCα and PKCβ may phosphorylate and activate ABCB1 under the control of p53. However, enzastaurin exerted similar effects on ABCB1 in the presence or absence of functional p53. Also, enzastaurin inhibited PKC signalling only in concentrations ≥ 1.25 μM. The investigated cell lines did not express PKCβ. PKCα depletion reduced PKC signalling but did not affect ABCB1 activity. Intracellular levels of the fluorescent ABCB1 substrate rhodamine 123 rapidly decreased after wash-out of extracellular enzastaurin, and enzastaurin induced ABCB1 ATPase activity resembling the ABCB1 substrate verapamil. Computational docking experiments detected a direct interaction of enzastaurin and ABCB1. These data suggest that enzastaurin directly interferes with ABCB1 function. Enzastaurin further inhibited ABCG2-mediated drug transport but by a different mechanism since it reduced ABCG2 ATPase activity. These findings are important for the further development of therapies combining enzastaurin with ABC transporter substrates.

Third- and further-line therapy in advanced non-small-cell lung cancer patients: an overview

Non-small-cell lung cancer (NSCLC) treatment has led to improved efficacy and compliance due to individual tailoring of the therapeutic options and the use of strategies based on both clinical characteristics and histological and biological features of the disease. In nonsquamous NSCLC, novel agents, such as pemetrexed and bevacizumab, have improved survival in the first-line setting. Maintenance therapy with pemetrexed and erlotinib resulted in improved progression-free survival compared with second-line therapy at disease progression. In the second-line setting, pemetrexed improves survival in nonsquamous NSCLC compared with docetaxel, and erlotinib has shown a survival benefit compared with best supportive care in patients who did not previously receive an EGF receptor inhibitor. Although the benefit of first- and second-line treatment over best supportive care alone has been firmly established, the role of further-line treatment remains controversial. This article summarizes the state-of-the-art treatments in this setting.

Targeting protein kinase C in sarcoma

Protein kinase C (PKC) is a family of serine/threonine tyrosine kinases that regulate many cellular processes including division, proliferation, survival, anoikis and polarity. PKC is abundant in many human cancers and aberrant PKC signalling has been demonstrated in cancer models. On this basis, PKC has become an attractive target for small molecule inhibition within oncology drug development programmes. Sarcoma is a heterogeneous group of mesenchymal malignancies. Due to their relative insensitivity to conventional chemotherapies and the increasing recognition of the driving molecular events of sarcomagenesis, sarcoma provides an excellent platform to test novel therapeutics. In this review we provide a structure-function overview of the PKC family, the rationale for targeting these kinases in sarcoma and the state of play with regard to PKC inhibition in the clinic.

Intra-lesional injection of the novel PKC activator EBC-46 rapidly ablates tumors in mouse models

Intra-lesional chemotherapy for treatment of cutaneous malignancies has been used for many decades, allowing higher local drug concentrations and less toxicity than systemic agents. Here we describe a novel diterpene ester, EBC-46, and provide preclinical data supporting its use as an intra-lesional treatment. A single injection of EBC-46 caused rapid inflammation and influx of blood, followed by eschar formation and rapid tumor ablation in a range of syngeneic and xenograft models. EBC-46 induced oxidative burst from purified human polymorphonuclear cells, which was prevented by the Protein Kinase C inhibitor bisindolylmaleimide-1. EBC-46 activated a more specific subset of PKC isoforms (PKC-βI, -βII, -α and -γ) compared to the structurally related phorbol 12-myristate 13-acetate (PMA). Although EBC-46 showed threefold less potency for inhibiting cell growth than PMA in vitro, it was more effective for cure of tumors in vivo. No viable tumor cells were evident four hours after injection by ex vivo culture. Pharmacokinetic profiles from treated mice indicated that EBC-46 was retained preferentially within the tumor, and resulted in significantly greater local responses (erythema, oedema) following intra-lesional injection compared with injection into normal skin. The efficacy of EBC-46 was reduced by co-injection with bisindolylmaleimide-1. Loss of vascular integrity following treatment was demonstrated by an increased permeability of endothelial cell monolayers in vitro and by CD31 immunostaining of treated tumors in vivo. Our results demonstrate that a single intra-lesional injection of EBC-46 causes PKC-dependent hemorrhagic necrosis, rapid tumor cell death and ultimate cure of solid tumors in pre-clinical models of cancer.

Reversal of multidrug resistance by cisplatin-loaded magnetic Fe3O4 nanoparticles in A549/DDP lung cancer cells in vitro and in vivo

The purpose of this study was to explore whether magnetic Fe(3)O(4) nanoparticles (Fe(3)O(4)-MNP) loaded with cisplatin (Fe(3)O(4)-MNP-DDP) can reverse DDP resistance in lung cancer cells and to investigate mechanisms of multidrug resistance in vitro and in vivo. MTT assay showed that DDP inhibited both A549 cells and DDP-resistant A549 cells in a time-dependent and dose-dependent manner, and that this inhibition was enhanced by Fe(3)O(4)-MNP. An increased rate of apoptosis was detected in the Fe(3)O(4)-MNP-DDP group compared with a control group and the Fe(3)O(4)-MNP group by flow cytometry, and typical morphologic features of apoptosis were confirmed by confocal microscopy. Accumulation of intracellular DDP in the Fe(3)O(4)-MNP-DDP group was greater than that in the DDP group by inductively coupled plasma mass spectrometry. Further, lower levels of multidrug resistance-associated protein-1, lung resistance-related protein, Akt, and Bad, and higher levels of caspase-3 genes and proteins, were demonstrated by reverse transcriptase polymerase chain reaction and Western blotting in the presence of Fe(3)O(4)-MNP-DDP. We also demonstrated that Fe(3)O(4)-MNP enhanced the effect of DDP on tumor growth in BALB/c nude mice bearing DDP-resistant human A549 xenografts by decreasing localization of lung resistance-related protein and Ki-67 immunoreactivity in cells. There were no apparent signs of toxicity in the animals. Overall, these findings suggest potential clinical application of Fe(3)O(4)-MNP-DDP to increase cytotoxicity in lung tumor xenografts.

Protein kinase C, an elusive therapeutic target?

Protein kinase C (PKC) has been a tantalizing target for drug discovery ever since it was first identified as the receptor for the tumour promoter phorbol ester in 1982. Although initial therapeutic efforts focused on cancer, additional indications--including diabetic complications, heart failure, myocardial infarction, pain and bipolar disorder--were targeted as researchers developed a better understanding of the roles of eight conventional and novel PKC isozymes in health and disease. Unfortunately, both academic and pharmaceutical efforts have yet to result in the approval of a single new drug that specifically targets PKC. Why does PKC remain an elusive drug target? This Review provides a short account of some of the efforts, challenges and opportunities in developing PKC modulators to address unmet clinical needs.

Phase 2 randomized study of enzastaurin (LY317615) for lung cancer prevention in former smokers

BACKGROUND

Chemoprevention for lung cancer with nutraceutical or anti-inflammatory agents has had mixed clinical benefit. Novel targeted agents hold the promise of greater efficacy and selectivity. The authors of this report evaluated enzastaurin, a selective protein kinase C-β (PKC-β) inhibitor with antiproliferative and proapoptotic properties, in former smokers.

METHODS

The primary objective of this study was to compare the average fraction of Ki-67-stained cells (the Ki-67 labeling index [LI]) in bronchial biopsy specimens that were collected before and after treatment. Participants were randomized (2:1) to receive either 6 months of daily oral enzastaurin (500 mg) or placebo. Stratification was based on morphology, history of lung cancer, and airway obstruction.

RESULTS

In pretrial investigations, the rationale for PKC-β inhibition and pathway interrogation was established in premalignant lesions and early stage lung cancer. In an intent-to-treat analysis, of 40 randomized participants, there was no significant difference in the pretreatment/post-treatment change in the Ki-67 LI between the enzastaurin group and the placebo group (P = .53). Six participants discontinued enzastaurin, including 4 participants who had adverse events, including abdominal distension, deep vein thrombosis, hyponatremia, and rash, and 2 participants who decided to discontinue. One participant in the placebo group was discontinued on the study because of noncompliance. Two participants had ≥1 serious adverse event (bradycardia, deep vein thrombosis, and hypotension).

CONCLUSIONS

To the authors' knowledge, this represents the first chemoprevention trial with a non-US Food and Drug Administration-approved, oral, small-molecule-targeted agent. Although the primary endpoint was not met, enzastaurin was tolerable for 6 months by 75% of participants, and there was a suggestion of response in a subset analysis that was restricted to those who had metaplastic or dysplastic lesions.

Enzastaurin has anti-tumour effects in lung cancers with overexpressed JAK pathway molecules

BACKGROUND

Enzastaurin, an oral serine-threonine kinase inhibitor, was initially developed as an ATP-competitive selective inhibitor against protein kinase Cβ. However, the mechanism by which enzastaurin contributes to tumourigenesis remains unclear.

METHODS

We analysed the anti-tumour effects of enzastaurin in 22 lung cancer cell lines to ascertain the potential for enzastaurin-based treatment of lung cancer. To identify molecules or signalling pathways associated with this sensitivity, we conducted a gene, receptor tyrosine kinases phosphorylation and microRNA expression profiling study on the same set of cell lines.

RESULTS

We identified eight genes by pathway analysis of molecules having gene-drug sensitivity correlation, and used them to build a support vector machine algorithm model by which sensitive cell lines were distinguished from resistant cell lines. Pathway analysis revealed that the JAK/STAT signalling pathway was one of the main ones involved in sensitivity to enzastaurin. Overexpression of JAK1 was observed in the sensitive cells by western blotting. Simultaneous administration of enzastaurin and JAK inhibitor inhibited enzastaurin-induced cell growth-inhibitory effect. Furthermore, lentiviral-mediated JAK1-overexpressing cells were more sensitive to enzastaurin than control cells.

CONCLUSION

Our results suggested that the JAK1 pathway may be used as a single predictive biomarker for enzastaurin treatment. The anti-tumour effect of enzastaurin should be evaluated in lung cancer with overexpressed JAK pathway molecules.

A phase I dose-escalation and pharmacokinetic study of enzastaurin and erlotinib in patients with advanced solid tumors

Purpose

Enzastaurin, an oral serine/threonine kinase inhibitor, targets the protein kinase C and AKT pathways with anti-tumor and anti-angiogenic effects. Erlotinib, an oral epidermal growth factor receptor (EGFR) inhibitor, has activity in solid tumors. Based on the promising combination of EGFR inhibitors and anti-angiogenic agents, this phase I trial was initiated.

Methods

This single-institution, open-label, non-randomized trial used a standard 3 + 3 dose-escalation model in patients with advanced solid malignancies including non-small-cell lung cancer (NSCLC). Two dose levels of enzastaurin (with loading doses) were explored: 250 mg daily and 500 mg daily. Erlotinib was given at 150 mg daily.

Results

Sixteen patients were enrolled in this study (median age, 64 years). Most patients were heavily pre-treated, female, and Caucasian and had NSCLC. The highest dose of enzastaurin, 500 mg daily, was tolerated with no unexpected adverse events and no alteration in the pharmacokinetics of either drug at this dose level. The mean clearance was 5.75 L/h for erlotinib and 53.8 L/h for enzastaurin. The most common possibly drug-related grade 3–4 adverse events included diarrhea (25.0%), neurologic symptoms (18.8%), and vomiting (18.8%). Activity was noted, with a partial response in one patient and prolonged disease stability for >12 cycles in three patients.

Conclusion

The combination of enzastaurin 500 mg daily and erlotinib 150 mg daily is well tolerated and does not alter the pharmacokinetics of the individual drugs, with clinical activity seen. A phase II trial of this combination has been initiated in patients with advanced-stage NSCLC.

Cardiotoxicity

Cancer treatment has improved extraordinarily in recent years. The development of targeted therapies has widened the cardiotoxic spectrum of antineoplastic drugs. Optimum management of cardiovascular disease before and during antineoplastic treatment is essential to reduce morbidity and mortality in cancer patients. This article reviews the incidence and characteristics of cardiotoxic effects of antineoplastic drugs with special focus on the pathophysiological mechanisms. It also emphasizes the importance of early detection and correction of cardiovascular risk factors and the relevance of close cardiac monitoring during antineoplastic treatment in order to reduce cardiotoxicity.

MET/PKCbeta expression correlate with metastasis and inhibition is synergistic in lung cancer

Background:

Treatment of non-small cell lung cancer (NSCLC) remains a difficult task in oncology. Targeted inhibition of oncogenic proteins is promising. In this study, we evaluate the expression of MET and PKCß and in vitro effects of their inhibition using SU11274 and enzastaurin (LY317615.HCl) respectively.

Materials and Methods:

Patient samples were analyzed by immunohistochemistry for expression of PKCß and MET, utilizing tissue microarrays under an IRB-approved protocol. Expression of PKCß and MET was evaluated in cell lines by immunoblotting. Treatment with SU1174 against MET and enzastaurin against PKCß was performed in H1993 and H358 cell lines, and cell proliferation and downstream signaling (phosphorylation of MET, AKT, FAK, and GSK3ß) were evaluated by immunoblotting. Statistical analysis was performed using SPSS 16.0.

Results:

Expression of MET positively correlated with lymph node metastases (p=.0004), whereas PKCß showed no correlation (p=0.204). MET and PKCß expression were also strongly correlated (p<0.001). Expression of MET was observed in 5/8 cell lines (H358, H1703, A549, H1993, H2170; absent from H522, H661, or SW1573), whereas PKCß expression was observed in 8/8 cell lines. Cell proliferation was significantly impaired by treatment with SU11274 and enzastaurin, and their effects were synergistic in combination (CI=0.32 and 0.09). Phosphorylation of MET, FAK, AKT, and GSK3ß were strongly inhibited with both agents in combination.

Conclusions:

Concomitant inhibition of MET and PKCß significantly increased cytotoxicity in vitro against NSCLC, disrupting important downstream signaling pathways. Further evaluation in animal models is warranted.

Targeting PKC-mediated signal transduction pathways using enzastaurin to promote apoptosis in acute myeloid leukemia-derived cell lines and blast cells

Recent studies in acute myeloid leukemia (AML) suggest activation of pro-proliferative signaling cascades including those mediated by protein kinase C (PKC) represent a poor prognostic factor for patients. The classical PKC isoforms α and β generally support survival signaling and have emerged as important targets for anti-cancer therapy. Enzastaurin is a PKC β inhibitor and is in clinical trials for lymphomas, gliomas, and lung cancer. Presently, it is not known if enzastaurin could be effective against AML. In the current study, we found that high dose enzastaurin was found to promote apoptosis in the AML-derived cell lines and in blast cells from AML patients. The mechanism of cell death, however, likely does not involve PKC β as another PKC β inhibitor was not toxic to AML cell lines and did not promote enzastaurin-induced cell killing. While enzastaurin is fairly specific for PKC β, the agent can inhibit other PKC isoforms at higher concentrations. Enzastaurin was effective at inhibiting PKC α phosphorylation and membrane localization in the AML cell lines and suppressed phosphorylation of BCL2. Furthermore, enzastaurin suppressed activation of ERK (which can be activated by PKC α). Analysis of the serine/threonine phosphorylation profile in HL60 cells after enzastaurin treatment revealed that the drug inhibits the phosphorylation of a distinct set of proteins while promoting phosphorylation of another set of proteins. This suggests the drug may regulate multiple signaling pathways. Taken together, these findings suggest that enzastaurin could be effective in the therapy of AML.

A Gynecologic Oncology Group phase II trial of the protein kinase C-beta inhibitor, enzastaurin and evaluation of markers with potential predictive and prognostic value in persistent or recurrent epithelial ovarian and primary peritoneal malignancies

OBJECTIVES

Protein kinase C (PKC) activation contributes to proliferation and angiogenesis in epithelial ovarian or primary peritoneal carcinoma (EOC/PPC). A multi-institutional phase II trial was conducted to evaluate the efficacy and safety of PKCβ inhibitor enzastaurin in persistent or recurrent EOC/PPC and to explore potential prognostic and predictive biomarkers.

METHODS

Eligible women with measurable platinum-sensitive and resistant EOC/PPC were treated with continuous administration of oral enzastaurin until disease progression or unacceptable toxicity. A two-stage sequential design was used to evaluate progression-free survival (PFS) ≥6-months, tumor response, and toxicity. Translational studies included sequencing of the TP53, PTEN, PIK3CA and PKCβII genes for somatic mutations, quantitative PCR assays for AKT2 and PTEN copy number alterations, and measurement of circulating VEGF-A plasma levels.

RESULTS

Among 27 eligible and evaluable patients, 3 women with PFS≥6-months (11%) and 2 women with partial responses (7%) were observed. One of them achieved a durable response and remains on the study. No grade 4 adverse events were observed. Most common grade 3 adverse events were constitutional (4) and gastrointestinal (3). Mutations in the TP53 gene and abnormal copy number in the PTEN gene were common (56% and 48% of cases, respectively).

CONCLUSIONS

Enzastaurin was tolerable but had insufficient activity to proceed with the second stage of accrual. However, 1 patient has been progression-free for 44 months. No association between a biomarker and response to enzastaurin has been found. Exploratory analysis suggested an association between survival and PTEN copy number losses.

Efficacy and safety of Rhus verniciflua stokes extracts in patients with previously treated advanced non-small cell lung cancer

BACKGROUND

Systemic treatments for advanced non-small cell lung cancer (NSCLC) have modest survival benefits but high toxicity. Rhus verniciflua Stokes (RVS), the lacquer tree, is an ancient traditional medicine being used for the treatment of cancer. We investigated the efficacy and safety of allergen-removed RVS extract (aRVS) for the prolongation of survival in NSCLC after the failure of first-line or second-line chemotherapy.

PATIENTS AND METHODS

We reviewed the medical records of 40 patients who were treated with aRVS for previously treated, advanced NSCLC at the M×μ Integrative Cancer Center, Korea, between June 2006 and June 2009. The primary objective of this study was to assess overall survival. Secondary objectives included assessments of disease control rates, progression-free survival, and the safety of aRVS treatment.

RESULTS

The median survival time was 8.4 months with a 1-year survival of 40%. The disease control rate was 63.6%, and the median progression-free survival interval was 3.9 months. Patients who had better performance status and adenocarcinoma experienced more favorable outcomes in terms of overall survival. in aRVS treatment were negligible, with the most common drug-related adverse events being mild epigastric pain and itching skin. Hematologic toxicity was absent.

CONCLUSIONS

Survival data and favorable levels of tolerability suggest the potential of aRVS treatment in previously treated patients with advanced NSCLC. Treatment with aRVS might be a viable alternative in patients for whom chemotherapy is not feasible, or who refuse chemotherapy.

Randomized, phase II trial of pemetrexed and carboplatin with or without enzastaurin versus docetaxel and carboplatin as first-line treatment of patients with stage IIIB/IV non-small cell lung cancer

INTRODUCTION

Enzastaurin is an oral serine/threonine kinase inhibitor that targets protein kinase C-beta (PKC-β) and the phosphatidylinositol-3-kinase/AKT pathway. This trial assessed pemetrexed-carboplatin ± enzastaurin to docetaxel-carboplatin in advanced non-small cell lung cancer.

METHODS

Patients with stage IIIB (with pleural effusion) or IV non-small cell lung cancer and performance status 0 or 1 were randomized to one of the three arms: (A) pemetrexed 500 mg/m and carboplatin area under the curve 6 once every 3 weeks for up to 6 cycles with a loading dose of enzastaurin 1125 or 1200 mg followed by 500 mg daily until disease progression, (B) the same regimen of pemetrexed-carboplatin without enzastaurin, or (C) docetaxel 75 mg/m and carboplatin area under the curve 6 once every 3 weeks for up to six cycles. The primary end point was time to disease progression (TTP).

RESULTS

Between March 2006 and May 2008, 218 patients were randomized. Median TTP was 4.6 months for pemetrexed-carboplatin-enzastaurin, 6.0 months for pemetrexed-carboplatin, and 4.1 months for docetaxel-carboplatin (differences not significant). Median survival was 7.2 months for pemetrexed-carboplatin-enzastaurin, 12.7 months for pemetrexed-carboplatin, and 9.2 months for docetaxel-carboplatin (log-rank p = 0.05). Compared with the other arms, docetaxel-carboplatin was associated with lower rates of grade 3 thrombocytopenia and anemia but a higher rate of grade 3 or 4 febrile neutropenia.

CONCLUSION

There was no difference in TTP between the three arms, but survival was longer with pemetrexed-carboplatin compared with docetaxel-carboplatin. Enzastaurin did not add to the activity of pemetrexed-carboplatin.

Randomized, double-blinded, multicenter, phase II study of pemetrexed, carboplatin, and bevacizumab with enzastaurin or placebo in chemonaïve patients with stage IIIB/IV non-small cell lung cancer: Hoosier Oncology Group LUN06-116

INTRODUCTION

: Bevacizumab is approved in combination with chemotherapy as first-line treatment for non-small cell lung cancer (NSCLC). Preclinical data suggest that enzastaurin and bevacizumab may have complementary effects in inhibiting angiogenesis.

METHODS

:

ELIGIBILITY CRITERIA

≥18 years of age, chemonaïve, stage IIIB/IV nonsquamous NSCLC, and Eastern Cooperative Oncology Group performance status 0 to 1. Patients were randomized to placebo or enzastaurin 500 mg orally daily (after a loading dose), plus pemetrexed 500 mg/m, carboplatin area under the curve 6, and bevacizumab 15 mg/kg, intravenously, every 21 days for four cycles. Patients without progression received maintenance therapy with bevacizumab and placebo or enzastaurin. The primary objective was progression-free survival (PFS). Planned sample size was 90 patients, one-sided alpha of 0.20, with two interim analyses: one for safety and the second for futility, with a PFS hazard ratio of 0.8857.

RESULTS

: Forty patients were randomized. No unique safety concerns were noted at the first interim analysis. The early stopping rule for futility was met at the second interim analysis. Median PFS was 3.5 months and 4.3 months (hazard ratio: 1.04, 95% confidence interval: 0.49-2.21), and response rates were 20% and 30% (p = 0.462) for enzastaurin and placebo, respectively. Grade 3 or 4 toxicity was similar between the two arms. Two patients died on study because of respiratory arrest and pulmonary embolism. An additional patient died of sepsis secondary to a gastrointestinal perforation >30 days after study treatment discontinuation.

CONCLUSIONS

: Enzastaurin does not improve efficacy when combined with pemetrexed, carboplatin, and bevacizumab. This combination does not warrant further study in NSCLC.

eEF-2 kinase dictates cross-talk between autophagy and apoptosis induced by Akt Inhibition, thereby modulating cytotoxicity of novel Akt inhibitor MK-2206

Inhibition of the survival kinase Akt can trigger apoptosis, and also has been found to activate autophagy, which may confound tumor attack. In this study, we investigated regulatory mechanisms through which apoptosis and autophagy were modulated in tumor cells subjected to Akt inhibition by MK-2206, the first allosteric small molecule inhibitor of Akt to enter clinical development. In human glioma cells, Akt inhibition by MK-2206 or siRNA-mediated attenuation strongly activated autophagy, whereas silencing of eukaryotic elongation factor-2 (eEF-2) kinase, a protein synthesis regulator, blunted this autophagic response. Suppression of MK-2206-induced autophagy by eEF-2 silencing was accompanied by a promotion of apoptotic cell death. Similarly, siRNA-mediated inhibition of eEF-2 kinase potentiated the efficacy of MK-2206 against glioma cells. Together, these results showed that blunting autophagy and augmenting apoptosis by inhibition of eEF-2 kinase could modulate the sensitivity of glioma cells to Akt inhibition. Our findings suggest that targeting eEF-2 kinase may reinforce the antitumor efficacy of Akt inhibitors such as MK-2206.

A phase I study of enzastaurin combined with pemetrexed in advanced non-small cell lung cancer

INTRODUCTION

Enzastaurin is an oral serine/threonine kinase inhibitor, which suppress signaling through protein kinase C-beta and the phosphatidylinositol 3-kinase/AKT pathway. Preclinical studies suggested synergic antitumor activity of enzastaurin and pemetrexed. We conducted this phase I study to evaluate the safety, pharmacokinetics, and clinical activity of this combination in patients with previously treated advanced non-small cell lung cancer.

METHODS

An oral daily dose of 500 mg enzastaurin was administered once daily (QD) or twice daily (BID) in combination with 500 mg/m pemetrexed on day 1 in repeated 21-day cycles. Cycle 1 started with a 7-day enzastaurin lead-in treatment that preceded pemetrexed administration: a loading dose of 1125 mg enzastaurin on day 1 followed by a 500 mg total daily dose on days 2-7.

RESULTS

Twelve patients were treated QD (n = 6) or BID (n = 6). One dose-limiting toxicity (grade 3 QTc prolongation) was reported in the QD cohort. Grade 3/4 hematological toxicities were slightly increased in the BID cohort compared with the QD cohort. After beginning the combination therapy, enzastaurin exposures decreased slightly but remained above the target plasma concentration of 1400 nmol/L. Compared with QD, there was a higher exposure with BID. The enzastaurin dosing regimen (QD or BID) had no effect on pemetrexed pharmacokinetics. Two patients had partial responses as defined by RECIST. Five patients received more than 10 cycles of treatment without disease progression.

CONCLUSIONS

Both schedules of enzastaurin in combination with pemetrexed were well tolerated and clinically active in patients with advanced non-small cell lung cancer.

Protein kinase C-beta gene variants, pathway activation, and enzastaurin activity in lung cancer

BACKGROUND

Protein kinase C-beta2 (PKCbeta2) is a splice-variant of the PRKCB1 gene and belongs to a family of serine/threonine-specific kinases that are predominantly activated by diacylglycerol, calcium, and phorbol ester. Cellular functions associated with PKCbeta2 activation include transformation, proliferation, and inhibition of apoptosis. Enzastaurin (LY317615) is an oral, selective, potent inhibitor of the PKCbeta2 kinase. Preclinical activity for this agent was predominantly reported in lymphoma, glioblastoma, and colorectal cancer. In patients with advanced non-small-cell lung cancer (NSCLC) whose previous therapy had failed, 13% of patients had disease control for 6 months with single-agent therapy.

PATIENTS AND METHODS

We investigated whether biologically relevant variants of PRKCB1 exist in lung cancer cell lines in the context of enzastaurin-induced proliferation and kinase inhibition, using exon sequencing, immunoblotting, and cytotoxicity assays in NSCLC and small-cell lung cancer (SCLC) cell lines.

RESULTS

We discovered a total of 6 single-nucleotide variants, but only 1 resulted in an amino acid substitution (T40I). This substitution was not located in the kinase domain of PKCbeta2 and did not affect enzastaurin's antiproliferative or phosphorylation-inhibitory activity. We found enzastaurin to be equally active in NSCLC and SCLC cell lines, with values of the 50% inhibitory concentration in a range of 0.05-0.2 microM.

CONCLUSION

The inhibition of phosphorylation of PKCbeta2 and the downstream molecules glycogen synthase kinase-3beta, S6RP, Akt, and forkhead transcription factor was evident in the same concentration range, which suggests the premise that the determination of phosphorylation levels of these molecules in human tissue specimens may be a useful pharmacodynamic parameter for in vivo target inhibition by enzastaurin.

Epidermal growth factor receptor inhibition in lung cancer: the evolving role of individualized therapy

Non-small cell lung cancer (NSCLC) is the major cause of cancer-related deaths in the USA and worldwide. Most patients present with advanced disease, and treatment options for these patients are generally limited to platinum-based chemotherapy and a few targeted therapies. Targeted agents currently in use for NSCLC inhibit oncogenic receptor tyrosine kinase pathways, such as the epidermal growth factor receptor (EGFR) pathway. While current EGFR-targeted agents, including erlotinib and gefitinib, may result in dramatic responses, they demonstrate efficacy in only a fraction of patients, and resistance to these agents frequently develops. In order to select patients most likely to benefit from blockade of EGFR pathways, investigators have focused on identifying molecular correlates of response to anti-EGFR therapy. New strategies to minimize the risk of resistance to EGFR inhibition have been employed in the development of next-generation EGFR tyrosine kinase inhibitors, such as PF00299804 and BIBW 2992; these include irreversibility of target binding, inhibition of multiple EGFR family receptors, and/or simultaneous inhibition of EGFR and other oncogenic pathways.

Cancer treatments: can we find treasures at the bottom of the sea?

Because of the poor results observed after platinum-based first-line chemotherapy, research on new strategies for second-line treatment of advanced non-small-cell lung cancer (NSCLC) is warranted. Current research focuses on the development of new agents and the assessment of a combination of therapies, especially those with different mechanisms of action. PM02734 (elisidepsin, Irvalec) is a compound related to Kahalalide F (KF), a moderately soluble marine product that belongs to a family of dehydro aminobutyric acid-containing peptides isolated from the herbivorous marine mollusk Elysia rufescens. Preclinical and clinical studies showed that KF induces strong cytotoxic activity against different solid tumors, including NSCLC, particularly in patients with squamous histology; in fact, almost 40% of patients treated in the second line were still alive at 1 year after beginning treatment with KF. Analysis of data collected during clinical development has revealed that KF has a predictable and manageable toxicity profile. The toxicities most commonly associated with KF are generally transient and mild or moderate. The absence of hematologic toxicity and cumulative toxic effects suggests that KF may be suitable for combination trials with other anticancer agents. The development of KF could stopped because of the unavailability of a natural source of the compound. PM02734 is a closely related derivative of KF with similar activity and characteristics. Herein, we summarize the studies of PM02734 and future clinical perspectives.

Enzastaurin induces H2AX phosphorylation to regulate apoptosis via MAPK signalling in malignant glioma cells

Enzastaurin is an acyclic bisindolylmaleimide derived from staurosporine that acts as an ATP competitor, and interferes with the activity of protein kinase C (PKC) isoforms. Our previous studies have shown that clinically achievable concentrations of this agent induce apoptosis in many glioma cell lines. Our goal in this study was to expand on the previous results and to determine the signalling mechanisms responsible for enzastaurin-induced inhibition of cell growth and induction of apoptosis. To address these issues, cell cycle progression following enzastaurin treatment was analysed by fluorescence-activated cell sorting (FACS) in parallel with analyses of growth and apoptosis signalling pathways. Enzastaurin treatment activated H2AX and Chk2 phosphorylation, and enhanced phosphorylation of mitogen-activated protein kinase (MAPK) family kinases. Inhibition of MAP kinases by chemical inhibitors reduced H2AX and Chk2 phosphorylation and decreased apoptosis induced by enzastaurin. These data call attention to a novel signalling pathway (MAPK/H2AX) to regulate apoptosis in malignant glioma cells.

Enzastaurin (LY317615), a protein kinase C beta selective inhibitor, enhances antiangiogenic effect of radiation

PURPOSE

Angiogenesis has generated interest in oncology because of its important role in cancer growth and progression, particularly when combined with cytotoxic therapies, such as radiotherapy. Among the numerous pathways influencing vascular growth and stability, inhibition of protein kinase B(Akt) or protein kinase C(PKC) can influence tumor blood vessels within tumor microvasculature. Therefore, we wanted to determine whether PKC inhibition could sensitize lung tumors to radiation.

METHODS AND MATERIALS

The combination of the selective PKCbeta inhibitor Enzastaurin (ENZ, LY317615) and ionizing radiation were used in cell culture and a mouse model of lung cancer. Lung cancer cell lines and human umbilical vascular endothelial cells (HUVEC) were examined using immunoblotting, cytotoxic assays including cell proliferation and clonogenic assays, and Matrigel endothelial tubule formation. In vivo, H460 lung cancer xenografts were examined for tumor vasculature and proliferation using immunohistochemistry.

RESULTS

ENZ effectively radiosensitizes HUVEC within in vitro models. Furthermore, concurrent ENZ treatment of lung cancer xenografts enhanced radiation-induced destruction of tumor vasculature and proliferation by IHC. However, tumor growth delay was not enhanced with combination treatment compared with either treatment alone. Analysis of downstream effectors revealed that HUVEC and the lung cancer cell lines differed in their response to ENZ and radiation such that only HUVEC demonstrate phosphorylated S6 suppression, which is downstream of mTOR. When ENZ was combined with the mTOR inhibitor, rapamycin, in H460 lung cancer cells, radiosensitization was observed.

CONCLUSION

PKC appears to be crucial for angiogenesis, and its inhibition by ENZ has potential to enhance radiotherapy in vivo.

Gemcitabine plus enzastaurin or single-agent gemcitabine in locally advanced or metastatic pancreatic cancer: results of a phase II, randomized, noncomparative study

PURPOSE

Gemcitabine (G) is standard therapy for pancreatic cancer. Enzastaurin (E) inhibits PKCβ and PI3K/AKT signaling pathways with a dose-dependent effect on growth of pancreatic carcinoma xenografts. Data suggest that the GE combination may improve clinical outcomes.

METHODS

Primary objective was overall survival (OS); secondary objectives assessed progression-free survival (PFS), response rate (RR), quality of life (QOL), toxicity, and relationships between biomarker expression and clinical outcomes. Patients were randomly assigned (2:1) to GE or G treatment; GE arm: E 500 mg p.o. daily; loading-dose (1200 mg; Day 1 Cycle 1 only) and G 1000 mg/m(2) i.v. Days 1, 8, and 15 in 28-day cycles; G arm: G as in GE. Biomarker expression was assessed by immunohistochemistry.

RESULTS

Randomization totaled 130 patients (GE = 86, G = 44); 121 patients were treated (GE = 82, G = 39). GE/G median OS was 5.6/5.1 months; median PFS was 3.4/3.0 months. GE responses: 1 complete response (CR, 1.2%), 6 partial response (PR, 7.4%), and 33 stable disease (SD, 40.7%); disease control rate (DCR=CR+PR+SD, 49.4%). G responses: 2 PR (5.3%) and 16 SD (42.1%); DCR (47.4%). No QOL differences were noted between arms. GE/G Grade 3-4 toxicities included: neutropenia (18.3%/28.2%); thrombocytopenia (14.6%/25.6%); and fatigue (11.0%/7.7%). No statistically significant relationships between biomarker expression and outcomes were observed. However, patients with low expression of cytoplasmic pGSK-3β trended toward greater OS with GE treatment.

CONCLUSIONS

OS, PFS, QOL, and RR were comparable between arms. Adding E to G did not increase hematologic toxicities. GE does not warrant further investigation in unselected pancreatic cancer patients.

Enzastaurin shows preclinical antitumor activity against human transitional cell carcinoma and enhances the activity of gemcitabine

Enzastaurin, an oral serine/threonine kinase inhibitor, suppresses signaling through protein kinase C (PKC)-beta and the phosphatidylinositol 3-kinase/AKT pathways. We preclinically evaluated enzastaurin alone and in combination with gemcitabine for transitional cell cancer (TCC). Immunohistochemistry (IHC) was done on 105 human samples from a microarray to show the expression of PKC-beta. The preclinical antitumor activity of enzastaurin and gemcitabine as single agents and in combination against aggressive human -lines (-SUP and 5637) and murine subcutaneous xenografts bearing 5637 cells was determined. Western Blot was done on tumor cells in vitro to detect signaling through PKC-beta, GSK-3beta, and AKT. The effect on cell migration was determined in vitro. Modulation of proliferation (Ki-67), apoptosis (cleaved caspase-3), and angiogenesis (CD31) in vivo was determined by IHC. IHC done on human TCC samples from a microarray showed the expression of PKC-beta in 33% of tumors. Enzastaurin induced significant apoptosis and inhibited proliferation in vitro at low micromolar concentrations. The in vitro inhibitory activity of combination enzastaurin and gemcitabine by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay seemed synergistic. Western Blotting revealed down-regulation of Akt, PKC-beta, and GSK-3 beta phosphorylation. Enzastaurin inhibited migration at an earlier time point independent of antiproliferative activity. Combination therapy had significantly superior antitumor activity in murine xenografts compared with untreated controls, whereas single agents did not. IHC showed reduced Ki-67 and CD31 and increased cleaved caspase-3 with combination therapy compared with controls. Enzastaurin showed preclinical antitumor activity against human TCC and enhanced the activity of gemcitabine.

Targeting angiogenesis via a c-Myc/hypoxia-inducible factor-1alpha-dependent pathway in multiple myeloma

Bone marrow angiogenesis is associated with multiple myeloma (MM) progression. Here, we report high constitutive hypoxia-inducible factor-1alpha (Hif-1alpha) expression in MM cells, which is associated with oncogenic c-Myc. A drug screen for anti-MM agents that decrease Hif-1alpha and c-Myc levels identified a variety of compounds, including bortezomib, lenalidomide, enzastaurin, and adaphostin. Functionally, based on transient knockdowns and overexpression, our data delineate a c-Myc/Hif-1alpha-dependent pathway mediating vascular endothelial growth factor production and secretion. The antiangiogenic activity of our tool compound, adaphostin, was subsequently shown in a zebrafish model and translated into a preclinical in vitro and in vivo model of MM in the bone marrow milieu. Our data, therefore, identify Hif-1alpha as a novel molecular target in MM and add another facet to anti-MM drug activity.

Protein kinase C-beta II (PKC-beta II) expression in patients with colorectal cancer

PURPOSE

Current development of targeted agents for the treatment of colorectal cancer include the clinical evaluation of kinase inhibitors, such as enzastaurin, a serine/threonine kinase inhibitor designed to suppress signaling through Protein Kinase C (PKC) and AKT pathways. Little is known about the expression of PKC-beta in colorectal cancer or the prognostic value in colorectal cancer, which was the focus of the present study.

METHODS

PKC-beta II protein expression was examined in 99 primary colorectal adenocarcinomas and 33 corresponding regional lymph node metastases by immunohistochemistry (IHC). The PKC-beta II immunoreactivity was mutually compared and correlated with survival information of all examined patients.

RESULTS

Immunohistochemical expression of PKC-beta II was detected in 18/99 carcinomas (18.2%). There was no correlation between PKC-beta II staining and traditional clinicopathological parameters. However the median survival was 2.2 years in PKC-beta II expressing tumors compared to 5.4 in PKC-beta II negative tumors (p = 0.25), with a trend for association to poor prognosis.

CONCLUSION

We here describe for the first time the immunohistochemical detection of PKC-beta II in patients with colorectal cancer and show a trend associating with poor survival. The role of PKC-beta II staining in colorectal tumors deserves further evaluation.

A phase I trial of enzastaurin in patients with recurrent gliomas

PURPOSE

Enzastaurin is a selective inhibitor of protein kinase C beta. Prior phase I studies did not show increased drug exposures with escalating once daily administration. Limits from gastrointestinal absorption may be overcome by twice daily dosing, potentially improving antitumor effects.

EXPERIMENTAL DESIGN

We conducted a phase I dose escalation study in 26 patients with recurrent malignant glioma, stratified by use of enzyme-inducing antiepileptic drugs, to investigate whether divided twice daily dosing results in higher exposures compared with once daily dosing. Phosphorylated glycogen synthase 3 beta was analyzed as a potential biomarker of enzastaurin activity.

RESULTS

Enzastaurin was poorly tolerated at all dose levels evaluated (500, 800, and 1,000 mg total daily), with thrombocytopenia and prolonged QTc as dose-limiting toxicities. The average drug concentration of enzastaurin under steady-state conditions was doubled by twice daily dosing compared with daily dosing [1.990; 90% confidence interval (CI), 1.450-2.730]. Additionally, geometric mean ratios doubled with 800 versus 500 mg dosing for both daily (2.687; 90% CI, 1.232-5.860) and twice daily regimens (1.852; 90% CI, 0.799-4.292). Two patients achieved long-term benefit (over 150 weeks progression free).

CONCLUSIONS

Higher and more frequent dosing of enzastaurin resulted in improved drug exposure but with unacceptable toxicity at the doses tested. Phosphorylated glycogen synthase 3 beta may be a useful biomarker of the biological activity of enzastaurin. Enzastaurin has activity in a subset of malignant glioma patients and warrants continued study in combination with other agents using a maximal once daily dose of 500 mg.

Synergistic effect of Sorafenib and Sunitinib with Enzastaurin, a selective protein kinase C inhibitor in renal cell carcinoma cell lines

Enzastaurin (LY317615.HCl) is an oral selective PKC-beta inhibitor with antiproliferative efficacy in various tumor models. This study was designed to investigate whether combination therapy with Enzastaurin and other targeted agents including Sorafenib and Sunitinib enhanced anti-tumor efficacy in renal cell carcinoma cell lines. Enzastaurin alone presented not active in renal cell carcinoma cell lines. Both Sorafenib and Sunitinib with Enzastaurin at concentrations feasible in vivo showed a synergistic reduction of viable RCC cells by inhibiting cell growth through inhibition of phospho-S6-kinase and GSK3-beta. The combination of Enzastaurin with Sorafenib and Sunitinib seems highly encouraging and warrants further investigation in vivo.

Association of single nucleotide polymorphisms in PIM-1 gene with the risk of Korean lung cancer

PURPOSE

The expression of the PIM-1 gene, which is a proto-oncogene that encodes a serine/threonine kinase, is associated with multiple cellular functions such as proliferation, differentiation, apoptosis and tumorigenesis. In particular, several studies have reported that the PIM-1 gene is associated with the development of lymphoma, leukemia and prostate cancer. Therefore, this study was conducted to evaluate the association between the single nucleotide polymorphisms in the PIM-1 gene and the risk of lung cancer occurrence in the Korean population.

MATERIALS AND METHODS

To evaluate the role of the PIM-1 gene in the development of lung cancer, the genotypes of the PIM-1 gene were determined in 408 lung cancer patients and 410 normal subjects.

RESULTS

We found that the T-C-T-C haplotypes of the PIM-1 gene (-1196 T>C, IVS4 +55 T>C, IVS4 +1416 T>A and +3684 C>A) were associated with an increased risk of lung cancer [adjusted odds ratio (aOR): 3.98; 95% CI: 1.24 approximately 12.75, p-value: 0.020]. In particular, these haplotypes showed an increased risk of lung cancer in males (aOR: 5.67; 95% CI: 1.32~24.30, p-value: 0.019) and smokers (aOR: 7.82; 95% CI: 1.75 approximately 34.98, p-value: 0.007).

CONCLUSIONS

The present results suggest that the T-C-T-C haplotype of the PIM-1 gene could influence the risk of developing smoking-related lung cancer in the Korean population. Additional functional studies with an larger sample sized analysis are warranted to reconfirm our findings.

In vivo/ex vivo and in situ assays used in cancer research: a brief review

Predicting whether a potential new anticancer agent will have a positive therapeutic index in patients remains a challenge. This brief review provides examples of preclinical in vivo/ex vivo and in situ assays used to assess the therapeutic potential of experimental anticancer therapeutics. Excision assays involving removal of tumor, bone marrow, and other tissues from the host after treatment to determine the effects of therapy in ex vivo assays are important preclinical tools. The survival of malignant cells from tumors treated in vivo and then excised is often determined by colony formation (CFU) in culture. When mice bearing in vivo alkylating agent-resistant tumors were treated with anticancer drugs such as cyclophosphamide, the survival pattern of bone marrow granulocyte-macrophage-colony forming units (CFU-GM) paralleled tumor cell survival. When TNP-470 and minocycline, an antiangiogenic combination, were added to treatment with cytotoxic anticancer therapies, tumor response markedly increased. TNP-470/minocycline-treated mice had higher tissue drug levels than did mice treated with the drug alone. Enzastaurin, an antiangiogenic protein kinase Cbeta inhibitor, treatment decreased intratumoral vessels to one half to one quarter of controls. Simultaneous and sequential treatment regimens with enzastaurin and BCNU delayed tumor growth and increased lifespan in mice bearing subcutaneous or intracranial human T98G glioblastoma multiforme. Both TNP-470 and enzastaurin have undergone clinical trials. Enzastaurin is currently in Phase III clinical trials.

Molecular pathways involved in the synergistic interaction of the PKC beta inhibitor enzastaurin with the antifolate pemetrexed in non-small cell lung cancer cells

Conventional regimens have limited impact against non-small cell lung cancer (NSCLC). Current research is focusing on multiple pathways as potential targets, and this study investigated molecular mechanisms underlying the combination of the PKCβ inhibitor enzastaurin with the multitargeted antifolate pemetrexed in the NSCLC cells SW1573 and A549. Pharmacologic interaction was studied using the combination-index method, while cell cycle, apoptosis induction, VEGF secretion and ERK1/2 and Akt phosphorylation were studied by flow cytometry and ELISAs. Reverse transcription–PCR, western blot and activity assays were performed to assess whether enzastaurin influenced thymidylate synthase (TS) and the expression of multiple targets involved in cancer signaling and cell cycle distribution. Enzastaurin-pemetrexed combination was highly synergistic and significantly increased apoptosis. Enzastaurin reduced both phosphoCdc25C, resulting in G2/M checkpoint abrogation and apoptosis induction in pemetrexed-damaged cells, and GSK3β and Akt phosphorylation, which was additionally reduced by drug combination (−58% in A549). Enzastaurin also significantly reduced pemetrexed-induced upregulation of TS expression, possibly through E2F-1 reduction, whereas the combination decreased TS in situ activity (>50% in both cell lines) and VEGF secretion. The effects of enzastaurin on signaling pathways involved in cell cycle control, apoptosis and angiogenesis, as well as on the expression of genes involved in pemetrexed activity provide a strong experimental basis to their evaluation as pharmacodynamic markers in clinical trials of enzastaurin-pemetrexed combination in NSCLC patients.