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

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 at the Crossroad of Mutations, Cancer, Targeted Therapy and Immune Response

The frequent PKC dysregulations observed in many tumors have made these enzymes natural targets for anticancer applications. Nevertheless, this considerable interest in the development of PKC modulators has not led to the expected therapeutic benefits, likely due to the complex biological activities regulated by PKC isoenzymes, often playing ambiguous and protective functions, further driven by the occurrence of mutations. The structure, regulation and functions of PKCs have been extensively covered in other publications. Herein, we focused on PKC alterations mostly associated with complete functional loss. We also addressed the modest yet encouraging results obtained targeting PKC in selected malignancies and the more frequent negative clinical outcomes. The reported observations advocate the need for more selective molecules and a better understanding of the involved pathways. Furthermore, we underlined the most relevant immune mechanisms controlled by PKC isoforms potentially impacting the immune checkpoint inhibitor blockade-mediated immune recovery. We believe that a comprehensive examination of the molecular features of the tumor microenvironment might improve clinical outcomes by tailoring PKC modulation. This approach can be further supported by the identification of potential response biomarkers, which may indicate patients who may benefit from the manipulation of distinctive PKC isoforms.

Amplified therapeutic targets in high-grade serous ovarian carcinoma - a review of the literature with quantitative appraisal

High-grade serous ovarian carcinoma is a unique cancer characterised by universal TP53 mutations and widespread copy number alterations. These copy number alterations include deletion of tumour suppressors and amplification of driver oncogenes. Given their key oncogenic roles, amplified driver genes are often proposed as therapeutic targets. For example, development of anti-HER2 agents has been clinically successful in treatment of ERBB2-amplified tumours. A wide scope of preclinical work has since investigated numerous amplified genes as potential therapeutic targets in high-grade serous ovarian carcinoma. However, variable experimental procedures (e.g., choice of cell lines), ambiguous phenotypes or lack of validation hinders further clinical translation of many targets. In this review, we collate the genes proposed to be amplified therapeutic targets in high-grade serous ovarian carcinoma, and quantitatively appraise the evidence in support of each candidate gene. Forty-four genes are found to have evidence as amplified therapeutic targets; the five highest scoring genes are CCNE1, PAX8, URI1, PRKCI and FAL1. This review generates an up-to-date list of amplified therapeutic target candidates for further development and proposes comprehensive criteria to assist amplified therapeutic target discovery in the future.

Activators and Inhibitors of Protein Kinase C (PKC): Their Applications in Clinical Trials

Protein kinase C (PKC), a family of phospholipid-dependent serine/threonine kinase, is classed into three subfamilies based on their structural and activation characteristics: conventional or classic PKC isozymes (cPKCs; α, βI, βII, and γ), novel or non-classic PKC isozymes (nPKCs; δ, ε, η, and θ), and atypical PKC isozymes (aPKCs; ζ, ι, and λ). PKC inhibitors and activators are used to understand PKC-mediated intracellular signaling pathways and for the diagnosis and treatment of various PKC-associated diseases, such as cancers, neurological diseases, cardiovascular diseases, and infections. Many clinical trials of PKC inhibitors in cancers showed no significant clinical benefits, meaning that there is a limitation to design a cancer therapeutic strategy targeting PKC alone. This review will focus on the activators and inhibitors of PKC and their applications in clinical trials.

Cellular Mechanism of Gene Mutations and Potential Therapeutic Targets in Ovarian Cancer

Ovarian cancer is a common and complex malignancy with poor prognostic outcome. Most women with ovarian cancer are diagnosed with advanced stage disease due to a lack of effective detection strategies in the early stage. Traditional treatment with cytoreductive surgery and platinum-based combination chemotherapy has not significantly improved prognosis and 5-year survival rates are still extremely poor. Therefore, novel treatment strategies are needed to improve the treatment of ovarian cancer patients. Recent advances of next generation sequencing technologies have both confirmed previous known mutated genes and discovered novel candidate genes in ovarian cancer. In this review, we illustrate recent advances in identifying ovarian cancer gene mutations, including those of TP53, BRCA1/2, PIK3CA, and KRAS genes. In addition, we discuss advances in targeting therapies for ovarian cancer based on these mutated genes in ovarian cancer. Further, we associate between detection of mutation genes by liquid biopsy and the potential early diagnostic value in ovarian cancer.

Evaluating the current status of protein kinase C (PKC)-protein kinase D (PKD) signalling axis as a novel therapeutic target in ovarian cancer

Ovarian cancer, especially high grade serous ovarian cancer is one of the most lethal gynaecological malignancies with high relapse rate and patient death. Notwithstanding development of several targeted treatment and immunotherapeutic approaches, researchers fail to turn ovarian cancer into a manageable disease. Protein kinase C (PKC) and protein kinase D (PKD) are families of evolutionarily conserved serine/threonine kinases that can be activated by a plethora of extracellular stimuli such as hormones, growth factors and G-protein coupled receptor agonists. Recent literature suggests that a signalling cascade initiated by these two protein kinases regulates a battery of cellular and physiological processes involved in tumorigenesis including cell proliferation, migration, invasion and angiogenesis. In an urgent need to discover novel therapeutic interventions against a deadly pathology like ovarian cancer, we have discussed the status quo of PKC/PKD signalling axis in context of this disease. Additionally, apart from discussing the structural properties and activation mechanisms of PKC/PKD, we have provided a comprehensive review of the recent reports on tumor promoting functions of PKC isoforms and discussed the potential of PKC/PKD signalling axis as a novel target in this lethal pathology. Furthermore, in this review, we have discussed the significance of several recent clinical trials and development of small molecule inhibitors that target PKC/PKD signalling axis in ovarian cancer.

PKCβII specifically regulates KCNQ1/KCNE1 channel membrane localization

The slow voltage-gated potassium channel (IKs) is composed of the KCNQ1 and KCNE1 subunits and is one of the major repolarizing currents in the heart. Activation of protein kinase C (PKC) has been linked to cardiac arrhythmias. Although PKC has been shown to be a regulator of a number of cardiac channels, including IKs, little is known about regulation of the channel by specific isoforms of PKC. Here we studied the role of different PKC isoforms on IKs channel membrane localization and function. Our studies focused on PKC isoforms that translocate to the plasma membrane in response to Gq-coupled receptor (GqPCR) stimulation: PKCα, PKCβI, PKCβII and PKCε. Prolonged stimulation of GqPCRs has been shown to decrease IKs membrane expression, but the specific role of each PKC isoform is unclear. Here we show that stimulation of calcium-dependent isoforms of PKC (cPKC) but not PKCε mimic receptor activation. In addition, we show that general PKCβ (LY-333531) and PKCβII inhibitors but not PKCα or PKCβI inhibitors blocked the effect of cPKC on the KCNQ1/KCNE1 channel. PKCβ inhibitors also blocked GqPCR-mediated decrease in channel membrane expression in cardiomyocytes. Direct activation of PKCβII using constitutively active PKCβII construct mimicked agonist-induced decrease in membrane expression and channel function, while dominant negative PKCβII showed no effect. This suggests that the KCNQ1/KCNE1 channel was not regulated by basal levels of PKCβII activity. Our results indicate that PKCβII is a specific regulator of IKs membrane localization. PKCβII expression and activation are strongly increased in many disease states, including heart disease and diabetes. Thus, our results suggest that PKCβII inhibition may protect against acquired QT prolongation associated with heart disease.

Kinase Inhibitors and Ovarian Cancer

Ovarian cancer is fifth in the rankings of cancer deaths among women, and accounts for more deaths than any other gynecological malignancy. Despite some improvement in overall-(OS) and progression-free survival (PFS) following surgery and first-line chemotherapy, there is a need for development of novel and more effective therapeutic strategies. In this mini review, we provide a summary of the current landscape of the clinical use of tyrosine kinase inhibitors (TKIs) and mechanistic target of rapamycin (mTOR) inhibitors in ovarian cancer. Emerging data from phase I and II trials reveals that a combinatorial treatment that includes TKIs and chemotherapy agents seems promising in terms of PFS despite some adverse effects recorded; whereas the use of mTOR inhibitors seems less effective. There is a need for further research into the inhibition of multiple signaling pathways in ovarian cancer and progression to phase III trials for drugs that seem most promising.

Phase II evaluation of dalantercept in the treatment of persistent or recurrent epithelial ovarian cancer: An NRG Oncology/Gynecologic Oncology Group study

OBJECTIVE

To determine the efficacy of dalantercept, a soluble ALK1 inhibitor receptor fusion protein, in patients with persistent or recurrent ovarian carcinoma and related malignancies.

METHODS

Eligibility criteria included measurable disease, 1-2 prior cytotoxic regimens and GOG performance status (PS) ≤2. Dalantercept was administered subcutaneously at 1.2 mg/kg every 3 weeks until disease progression or development of unacceptable toxicity. The primary null hypothesis was the probability of response ≤0.10 and the probability of 6-month progression-free survival without receipt of non-protocol therapy (event-free survival at 6 months, EFS6) ≤0.15, using RECIST 1.1 criteria.

RESULTS

The first stage was closed after enrollment of 30 participants with median age of 56.5 years, high-grade serous histology in 76.7%, 2 prior regimens in 46.7%, and platinum-free interval <6 months in 73.3%. All participants discontinued dalantercept, 24 (80.0%), 5 (16.7%) and 1 (3.3%) due to progression, toxicity, and other reason, respectively. The median number of treatment cycles per patient was 2 (range 1-29). There were six treatment-related grade 3 AEs and no grade ≥4 AEs. There were no objective responses. EFS6 was reached in 20% (6 out of 30 participants, 90% CI 9.1% to 35.7%).

CONCLUSIONS

Though safe, dalantercept as administered had limited efficacy in this patient population overall.

Clinical trials in gynecologic oncology: Past, present, and future

The Gynecologic Oncology Group has historically performed ground-breaking, practice-changing clinical trials in women's cancers. The current standard of care for initial treatment of ovarian, endometrial, cervical, and trophoblastic cancers was determined by clinical trials completed within this cooperative group structure. For example, trial GOG-0111 set the standard for combining platinum and taxane chemotherapy in ovarian cancer, and more recently GOG-0240 provided evidence for adding bevacizumab to chemotherapy for women with advanced cervical cancer. The landscape of clinical trial design has markedly changed in recent decades, with a clear emphasis on streamlining drug development towards specific patient populations and indications for investigational agents. Translational science in gynecologic cancers can set the stage for rapid and efficient introduction of new therapies for our patients. The gynecologic oncology community of researchers and clinicians is well positioned to enter into the new era of drug development, with breakthrough discoveries increasing each year. It is clear that we must incorporate smarter clinical trial design to get the right drugs to the right patients expeditiously, so we can continue to improve outcome for women with gynecologic cancers.

A pharmacokinetic and safety study of a fixed oral dose of enzastaurin HCl in native Chinese patients with refractory solid tumors and lymphoma

Purpose

This study was conducted to assess the pharmacokinetics and safety of enzastaurin in native Chinese patients with refractory solid tumors and lymphoma.

Methods

Eligible patients received 500 mg of enzastaurin orally once daily. The pharmacokinetics of enzastaurin and its metabolites were assessed on days 14 to 18. Patients were allowed to continue receiving the agent in a safety extension phase until disease progression or presentation with unacceptable toxicity.

Results

Twenty-five patients received at least 1 dose of enzastaurin, and twenty-one patients completed the pharmacokinetic phase. Fifteen patients entered the safety extension phase. Except for transient, asymptomatic grade 3 QT interval prolongation in one patient who had baseline grade 2 QT prolongation, other adverse events were of grade 1 to 2. The t_1/2, C_{av, ss,} and AUC_{τ, ss} for enzastaurin and its primary active metabolite LSN326020 were 14 and 42 h, 1,210 and 907 nmol/L, and 29,100 and 21,800 nmol•h/L, respectively. One patient with relapsed diffuse large B-cell lymphoma achieved a partial response that lasted for 8.1 months.

Conclusions

The pharmacokinetics of enzastaurin in Chinese cancer patients were consistent with those observed in previous studies abroad. Enzastaurin 500 mg daily was well tolerated by Chinese patients. We recommend 500 mg daily as the phase II dose in this population. Its efficacy in lymphoma deserves further investigation.

Trial Registration

ClinicalTrials.gov: NCT01432951

Novel N-pyrimidin-4-yl-3-amino-pyrrolo [3, 4-C] pyrazole derivatives as PKC kinase inhibitors: a patent evaluation of US2015099743 (A1)

INTRODUCTION

Protein kinase Cβ (PKCβ) is a member of the PKC family of serine/threonine kinases that has been implicated in the pathophysiology of diabetic complications. Developing small molecule drugs targeting this PKC isozyme is a rational approach for treating these disease states. PKCβ belongs to the conventional class of PKC and contains both regulatory and kinase domain. Numerous compounds of different chemical classes were designed targeting the kinase domain, but achieved very limited success in clinical trials.

AREAS COVERED

This patent application reports the synthesis of about 100 new N-pyrimidin-4-yl-3-amino-pyrolo [3, 4-C] pyrazole derivatives and their competitive inhibition constant (Ki) for protein kinase C βII (PKCβII), one of the two splice variants of PKCβ. The compounds compete with ATP at the kinase domain of PKCβII, and inhibit with high potency having Ki values in the 0.1-181 nM range. The compounds are claimed to be selective towards PKCβI, PKCβII and PKCα over other protein kinases. Several routes of administration of these compounds are discussed for possible treatment of diabetes and related diseases.

EXPERT OPINION

This is an important effort toward developing PKC-based drugs for diabetic complications. Further biological evaluations of these compounds are required before proceeding toward clinical trails.

An overview of tyrosine kinase inhibitors for the treatment of epithelial ovarian cancer

INTRODUCTION

Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy and the fifth most common cause of cancer-related deaths in women. Initial treatment with surgery and chemotherapy has improved survival significantly. However, the disease progresses or recurs in most patients. Thus, there is an urgent need to develop more effective treatment strategies.

AREAS COVERED

This article provides an overview of tyrosine kinase inhibitors (TKIs) for the treatment of EOC, which is based on English peer-reviewed articles on MEDLINE and related abstracts presented at major conferences. The authors highlight the data from the published clinical trials in EOC patients who were treated with TKIs or TKI-based regimens.

EXPERT OPINION

EOC is responsive to most chemotherapeutic drugs and/or biological agents and represents an ideal disease model for investigating novel anti-cancer agents. Numerous small-molecule TKIs targeting the VEGFR, PARP, PI3K-AKT-mTOR, MAPK, Src, PKC, Wee1 and HER1/2 signaling pathways are currently being tested in clinical trials. Research is needed for devising regimens combining TKIs with other agents in an optimal timing schedule and for identifying potential biomarkers predictive of response and survival.

Increased expression of neuropilin 1 is associated with epithelial ovarian carcinoma

Neuropilin 1 (NRP1) is a transmembrane glycoprotein, which interacts with vascular endothelial growth factor to prevent tumor cell apoptosis and to regulate angiogenesis. However, the precise role of NRP1 in epithelial ovarian carcinoma (EOC) remains to be elucidated. The present study aimed to determine the association between NRP1 and EOC. The expression of NRP1 in ovarian cancer and normal ovarian epithelial tissues was investigated by immunofluorescence, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting. The association between the expression of NRP1 with the development of ovarian cancer, clinicopathological characteristics and survival were also analyzed. The results from immunofluorescence, RT-qPCR and western blot analysis demonstrated that NRP1 exhibited significant upregulation in EOC compared with normal ovarian epithelial specimens (P<0.05). The positive expression of NRP1 was higher in cancer tissues at an advanced International Federation of Gynecology and Obstetrics stage, and in cancer tissues with lymph node metastasis and distant metastasis compared with that in cancer tissues without lymph node or distant metastasis (P<0.05). Higher NRP1 expression strongly predicted a shorter survival time (P<0.001). The present findings suggested that increased NRP1 expression may be associated with the development of EOC. Therefore, NRP1 could be used as a valuable prognostic marker as well as a potential molecular therapy target for ovarian cancer patients.

Decreased semaphorin 3A expression is associated with a poor prognosis in patients with epithelial ovarian carcinoma

Semaphorin 3A (SEMA3A) was initially identified to play an important role in axonal guidance. Recently, SEMA3A has also been considered as a candidate tumor suppressor, since it is often downregulated in numerous types of cancer, including prostate cancer, breast cancer and glioma. However, the biological role of SEMA3A in ovarian cancer is not clear. In the present study, the expression of SEMA3A in ovarian cancer and normal ovarian epithelial tissues was detected by immunofluorescence, reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blotting, and the associations between the expression of SEMA3A with the development of ovarian cancer, clinicopathological characteristics and survival were also analyzed. Results from immunofluorescence, RT‑qPCR and western blotting showed that SEMA3A is significantly downregulated in epithelial ovarian carcinoma compared to normal ovarian epithelial specimens (P<0.05). The expression levels of SEMA3A were lower in the cancer tissues with III/IV stage [the International Federation of Gynecology and Obstetrics (FIGO) stage], poor histological grade, lymph node metastasis and distant metastasis compared to that in the cancer tissues with I/II stage (FIGO), well histological grade, or without lymph node metastasis and distant metastasis (P<0.05). A decreased expression of SEMA3A is associated with a poor prognosis (P<0.001). The present findings suggest that decreased SEMA3A expression may be associated with the development of epithelial ovarian carcinoma, and therefore, SEMA3A may be a valuable prognostic marker, as well as a potential molecular therapy target for ovarian cancer patients.

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.

Integrative Pathway Analysis Using Graph-Based Learning with Applications to TCGA Colon and Ovarian Data

Recent method development has included multi-dimensional genomic data algorithms because such methods have more accurately predicted clinical phenotypes related to disease. This study is the first to conduct an integrative genomic pathway-based analysis with a graph-based learning algorithm. The methodology of this analysis, graph-based semi-supervised learning, detects pathways that improve prediction of a dichotomous variable, which in this study is cancer stage. This analysis integrates genome-level gene expression, methylation, and single nucleotide polymorphism (SNP) data in serous cystadenocarcinoma (OV) and colon adenocarcinoma (COAD). The top 10 ranked predictive pathways in COAD and OV were biologically relevant to their respective cancer stages and significantly enhanced prediction accuracy and area under the ROC curve (AUC) when compared to single data-type analyses. This method is an effective way to simultaneously predict binary clinical phenotypes and discover their biological mechanisms.

Pathway modulations and epigenetic alterations in ovarian tumorbiogenesis

Cellular pathways are numerous and are highly integrated in function in the control of cellular systems. They collectively regulate cell division, proliferation, survival and apoptosis of cells and mutagenesis of key genes that control these pathways can initiate neoplastic transformations. Understanding these pathways is crucial to future therapeutic and preventive strategies of the disease. Ovarian cancers are of three major types; epithelial, germ-cell, and stromal. However, ovarian cancers of epithelial origin, arising from the mesothelium, are the predominant form. Of the subtypes of ovarian cancer, the high-grade serous tumors are fatal, with low survival rate due to late detection and poor response to treatments. Close examination of preserved ovarian tissues and in vitro studies have provided insights into the mechanistic changes occurring in cells mediated by a few key genes. This review will focus on pathways and key genes of the pathways that are mutated or have aberrant functions in the pathology of ovarian cancer. Non-genetic mechanisms that are gaining prominence in the pathology of ovarian cancer, miRNAs and epigenetics, will also be discussed in the review.

A phase II evaluation of AMG 102 (rilotumumab) in the treatment of persistent or recurrent epithelial ovarian, fallopian tube or primary peritoneal carcinoma: a Gynecologic Oncology Group study

OBJECTIVE

This open-label, multi-institutional phase II trial evaluated activity and safety of rilotumumab (AMG 102), a monoclonal antibody that targets HGF (hepatocyte growth factor), the ligand for the MET receptor, in women with recurrent or persistent epithelial ovarian, fallopian tube or primary peritoneal cancer.

PATIENTS AND METHODS

Women were eligible for treatment with rilotumumab if they had measurable disease, a performance status of 0, 1 or 2, previously received platinum-based therapy with a progression-free interval of <12 months or a second recurrence, and adequate bone marrow and organ function. Patients received rilotumumab 20mg/kg IV every 14 days until evidence of unacceptable toxicity or disease progression. The study utilized co-dual primary endpoints of tumor response and six-month PFS to assess the efficacy of rilotumumab. Secondary endpoints included the frequency and severity of adverse events and the duration of progression-free and overall survival.

RESULTS

Thirty-one women enrolled and received rilotumumab. All were eligible for analysis. One patient achieved a complete response (3.2%; 90% CI 0.2-14%), and two women had 6-month PFS (6.5%; 90% CI 1.1-19%). Most adverse events were grade 1 or 2, with no grade 4 adverse events. Grade 3 adverse events were gastrointestinal (4), metabolic (3) anemia (3), a thromboembolic event (1), ventricular tachycardia (1), hypotension during infusion (1) and fatigue (1). The study was stopped after the first stage of accrual.

CONCLUSION

Rilotumumab was well-tolerated, but had limited activity. The level of activity does not warrant further evaluation of rilotumumab as a single agent in patients with ovarian cancer.

Effect of indirect nonequilibrium atmospheric pressure plasma on anti-proliferative activity against chronic chemo-resistant ovarian cancer cells in vitro and in vivo

PURPOSE

Nonequilibrium atmospheric pressure plasma (NEAPP) therapy has recently been focused on as a novel medical practice. Using cells with acquired paclitaxel/cisplatin resistance, we elucidated effects of indirect NEAPP-activated medium (NEAPP-AM) exposure on cell viability and tumor growth in vitro and in vivo.

METHODS

Using chronic paclitaxel/cisplatin-resistant ovarian cancer cells, we applied indirect NEAPP-exposed medium to cells and xenografted tumors in a mouse model. Furthermore, we examined the role of reactive oxygen species (ROS) or their scavengers in the above-mentioned EOC cells.

RESULTS

We assessed the viability of NOS2 and NOS3 cells exposed to NEAPP-AM, which was prepared beforehand by irradiation with NEAPP for the indicated time. In NOS2 cells, viability decreased by approximately 30% after NEAPP-AM 120-sec treatment (P<0.01). The growth-inhibitory effects of NEAPP-AM were completely inhibited by N-acetyl cysteine treatment, while L-buthionine-[S, R]-sulfoximine, an inhibitor of the ROS scavenger used with NEAPP-AM, decreased cell viability by 85% after NEAPP-AM 60-sec treatment(P<0.05) and by 52% after 120 sec, compared to the control (P<0.01). In the murine subcutaneous tumor-formation model, NEAPP-AM injection resulted in an average inhibition of the NOS2 cell-inoculated tumor by 66% (P<0.05) and NOS2TR cell-inoculated tumor by 52% (P<0.05), as compared with the control.

CONCLUSION

We demonstrated that plasma-activated medium also had an anti-tumor effect on chemo-resistant cells in vitro and in vivo. Indirect plasma therapy is a promising treatment option for EOC and may contribute to a better patient prognosis in the future.

Network analysis identifies an HSP90-central hub susceptible in ovarian cancer

PURPOSE

Epithelial ovarian cancer (EOC) is usually detected at an advanced stage and is frequently lethal. Although many patients respond to initial surgery and standard chemotherapy consisting of a platinum-based agent and a taxane, most experience recurrence and eventually treatment-resistant disease. Although there have been numerous efforts to apply protein-targeted agents in EOC, these studies have so far documented little efficacy. Our goal was to identify broadly susceptible signaling proteins or pathways in EOC.

EXPERIMENTAL DESIGN

As a new approach, we conducted data-mining meta-analyses integrating results from multiple siRNA screens to identify gene targets that showed significant inhibition of cell growth. On the basis of this meta-analysis, we established that many genes with such activity were clients of the protein chaperone HSP90. We therefore assessed ganetespib, a clinically promising second-generation small-molecule HSP90 inhibitor, for activity against EOC, both as a single agent and in combination with cytotoxic and targeted therapeutic agents.

RESULTS

Ganetespib significantly reduced cell growth, induced cell-cycle arrest and apoptosis in vitro, inhibited growth of orthotopic xenografts and spontaneous ovarian tumors in transgenic mice in vivo, and inhibited expression and activation of numerous proteins linked to EOC progression. Importantly, paclitaxel significantly potentiated ganetespib activity in cultured cells and tumors. Moreover, combined treatment of cells with ganetespib and siRNAs or small molecules inhibiting genes identified in the meta-analysis in several cases resulted in enhanced activity.

CONCLUSION

These results strongly support investigation of ganetespib, a single-targeted agent with effects on numerous proteins and pathways, in augmenting standard EOC therapies.

Randomized, Phase II, Placebo-Controlled, Double-Blind Study With and Without Enzastaurin in Combination With Paclitaxel and Carboplatin As First-Line Treatment Followed by Maintenance Treatment in Advanced Ovarian Cancer

Purpose

Enzastaurin is an oral serine/threonine kinase inhibitor antitumor agent. Our phase II trial tested the efficacy and safety of enzastaurin added to a standard carboplatin/paclitaxel chemotherapy regimen in patients with newly diagnosed advanced ovarian cancer.

Patients and Methods

This was a randomized, placebo-controlled study in patients with International Federation of Gynecology and Obstetrics stage IIB to IV ovarian, fallopian tube, or peritoneal epithelial carcinoma. Patients were randomly assigned to six cycles of chemotherapy (paclitaxel/carboplatin ± enzastaurin [PCE/PC]) followed by maintenance therapy (enzastaurin/placebo). Primary end point was progression-free survival (PFS). Secondary measures included response rate, safety assessment, and translational research.

Results

A total of 142 patients were randomly assigned to PCE (n = 69) or PC (n = 73). Patients in the PCE group had a 3.7-month longer median PFS compared with patients in the PC group; this was not statistically significant (hazard ratio [HR], 0.80; 95% CI, 0.50 to 1.29; P = .37). Safety profiles of the treatment arms were comparable. Frequency of discontinuation because of adverse events was similar (PCE, 11.9%; PC, 9.7%). Multivariate analyses confirmed the importance of optimal debulking with regard to PFS (debulking optimal v suboptimal: HR, 0.51; 95% CI, 0.30 to 0.85; P = .009). HR for covariate stage (stage IIB to IIIB v IIIC to IV) was not statistically significant (0.75; 95% CI, 0.38 to 1.47; P = .40). Translational research of immunohistochemistry protein assays did not identify any markers significantly associated with treatment difference regarding PFS.

Conclusion

The PCE combination increased PFS, but it was not significantly superior to PC in this phase II study.

A phase II evaluation of motesanib (AMG 706) in the treatment of persistent or recurrent ovarian, fallopian tube and primary peritoneal carcinomas: a Gynecologic Oncology Group study

OBJECTIVES

Vascular endothelial growth factors (VEGF) and their receptors have a critical role in stimulating the growth of ovarian cancer cells. Motesanib is a small molecule inhibitor of multiple receptor tyrosine kinases including VEGF receptors 1-3, as well as c-KIT and platelet-derived growth factor which are related to the VEGF family.

PATIENTS AND METHODS

Twenty-two eligible patients with recurrent ovarian, fallopian tube or primary peritoneal carcinoma were treated with an oral daily dose of 125 mg of motesanib. Peripheral blood was analyzed for circulating tumor cells (CTC) and circulating endothelial cells/circulating endothelial progenitors (CEC/CEP), VEGF levels and cell-free circulating DNA (cfDNA).

RESULTS

The study was abruptly halted after four patients developed posterior reversible encephalopathy syndrome. One patient had a partial response and seven patients had stable disease at the time they were removed from study treatment. Twelve of the 22 patients (50%) had indeterminate responses at trial closure. Early closure without clinical efficacy data precludes meaningful correlative studies.

CONCLUSIONS

The serious central nervous system toxicity observed in patients with recurrent ovarian cancer precluded full examination of this agent in this population. There were no clear cut explanations for the high incidence of this known class effect in the study population compared with patients with other cancers.

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.

Clinical trials and future potential of targeted therapy for ovarian cancer

Ovarian cancer is the leading cause of death in women with gynecological cancer. Most patients are diagnosed at an advanced stage with a poor prognosis. Currently, surgical tumor debulking followed by chemotherapy based on platinum and taxane is the standard treatment for advanced disease. However, these patients remain at great risk for recurrence and developing drug resistance. Therefore, new treatment strategies are needed to improve outcomes for patients with advanced and recurrent ovarian cancer. Several agents targeted at particular molecules have been developed for ovarian cancer and are now entering clinical trials. The functional targets of these agents are aberrations in tumor tissues including angiogenesis, the human epidermal growth factor receptor family, poly(ADP-ribose) polymerase (PARP), mammalian target of rapamycin (mTOR) signaling pathway, and α-folate receptor (α-FR). The anti-angiogenic compound bevacizumab has been reported as the most effective targeted agent. Bevacizumab plus chemotherapy prolonged progression-free survival (PFS) both for advanced and platinum-sensitive recurrent ovarian cancer, but did not increase overall survival. A PARP inhibitor, olaparib, applied as maintenance treatment also improved PFS in platinum-sensitive relapsed ovarian cancer. Furthermore, mTOR inhibitors and a monoclonal antibody to α-FR, farletuzumab, are attractive treatment strategies either alone or combined with chemotherapy. Understanding the tumor molecular biology and identifying predictive biomarkers are essential steps in selecting the best treatment strategies. This article reviews available clinical data on the most promising targeted agents for ovarian cancer.

Clinical utility of targeted treatments in the management of epithelial ovarian cancer

Epithelial ovarian cancer is typically found in its advanced stages, where a combination of surgical debulking and platinum/taxane-based chemotherapy is recommended. Although over 70%-80% of patients achieve remission, a significant proportion develop recurrence of their disease. Additional cytotoxic chemotherapy, as well as surgery, is typically used to manage disease recurrence. Therapies that target specific pathways in cancer cells are rapidly developing in the laboratory and are increasingly being studied in patients with ovarian cancer. We review the current status of novel therapies in the management of epithelial ovarian cancer.

Evolution of the Gynecologic Oncology Group protocols in the treatment of epithelial ovarian cancer

This chapter reviews some of the sentinel Gynecologic Oncology Group (GOG) ovarian trials, describes their rationale, provides summary tables for reference, and is organized into early ovarian cancer (GOG 1, 7601, 7602, 95, 157, 175, 212), advanced ovarian cancer optimal (2, 25, 52, 104, 114, 158, 172, 182, 178, 212, 252), and suboptimal disease (3, 22, 47, 97, 111, 162, 182, 218, 252, 262).

Phase I study of enzastaurin and bevacizumab in patients with advanced cancer: safety, efficacy and pharmacokinetics

Purpose Given distinct mechanism of actions of enzastaurin and bevacizumab, preclinical studies suggest enhanced antitumor activity in combination. This phase I study assessed the combination’s safety and efficacy. Patients and methods Six advanced cancer patients could be enrolled in each of 11 cohorts. Patients received an enzastaurin loading dose. Oral enzastaurin (500 mg once daily [QD], 250 mg twice daily [BID], 375 mg BID, 500 mg BID, and 750 mg BID) was escalated in each cohort in combination with bevacizumab dosed at 5 mg/kg every 2 weeks, 10 mg/kg every 2 weeks, or 15 mg/kg every 3 weeks until a dose-limiting toxicity (DLT) occurred in 2 of 6 patients in any cohort. Results Sixty-seven patients (31, ovarian cancer [ovcar]) were evaluable for safety and efficacy. Six treatment-related DLTs occurred: grade 3 fatigue (n = 4), grade 4 cerebral hemorrhage, and grade 3 elevated aspartate transaminase. Common drug-related toxicities included change in color of urine and stool, fatigue, pain, diarrhea, and nausea. The maximum tolerated dose of enzastaurin was 750 mg BID in combination with any tested bevacizumab dose/schedule. Overall response rate was 19.4 % (32.3 % ovcar). Median time to progression was 3.7 months (95 % confidence interval [CI], 2.7–5.5), with 8.3 months (95 % CI, 3.7–11.1) in ovcar. Overall, 35.9 % (50.4 % ovcar) of patients remained without disease progression after 6 months. Conclusion The recommended phase II doses of enzastaurin were 500 mg QD up to 500 mg BID with any tested dose/schedule of bevacizumab. This combination demonstrated encouraging clinical activity, particularly in ovcar.

A double-blind, randomized, placebo-controlled, phase 2 study of maintenance enzastaurin with 5-fluorouracil/leucovorin plus bevacizumab after first-line therapy for metastatic colorectal cancer

BACKGROUND

Enzastaurin and bevacizumab have demonstrated synergistic antitumor effects and, in phase 1 studies, the combination was well tolerated. This phase 2 study assessed enzastaurin with 5-fluorouracil/leucovorin plus bevacizumab as maintenance therapy for metastatic colorectal cancer (MCRC).

METHODS

Patients with locally advanced or MCRC and stable or responding disease after completing 6 cycles of first-line chemotherapy randomly received a loading dose of enzastaurin 1125 mg, followed by 500 mg/d subsequent doses or placebo. Both arms received 5-fluorouracil/leucovorin (leucovorin 400 mg/m(2) intravenously [IV], 5-fluorouracil 400-mg/m(2) bolus, 5-fluorouracil 2400 mg/m(2) IV) plus bevacizumab 5 mg/kg IV, every 2 weeks. The primary endpoint was progression-free survival (PFS), from randomization. Overall survival (OS) and PFS were also assessed from start of first-line therapy. Enrollment was stopped, and the final analysis was conducted after 73 PFS events.

RESULTS

Fifty-eight patients were randomized to enzastaurin and 59 to placebo. For the enzastaurin and placebo arms, respectively, the median cycles received were 9 and 10, and the median PFS was 5.8 and 8.1 months (hazard ratio [HR], 1.35; 95% confidence interval [CI], 0.84-2.16; P = .896). Median OS was not calculable because of high censoring (77.6% enzastaurin; 91.5% placebo). The median PFS from start of first-line therapy was 8.9 months for enzastaurin and 11.3 months for placebo (HR, 1.39; 95% CI, 0.86-2.23; P = .913). More enzastaurin patients developed thrombosis or embolism compared with placebo (15.8% and 1.7%; P = .008). One possibly enzastaurin-related death occurred because of arrhythmia.

CONCLUSIONS

Enzastaurin combined with bevacizumab-based therapy is tolerable, but does not improve PFS during maintenance therapy in patients with MCRC compared with bevacizumab-based therapy alone.

Phase II trial of the mTOR inhibitor, temsirolimus and evaluation of circulating tumor cells and tumor biomarkers in persistent and recurrent epithelial ovarian and primary peritoneal malignancies: a Gynecologic Oncology Group study

OBJECTIVE

Patients with persistent/recurrent epithelial ovarian cancer/primary peritoneal cancer (EOC/PPC) have limited treatment options. AKT and PI3K pathway activation is common in EOC/PPC, resulting in constitutive activation of downstream mTOR. The GOG conducted a phase II evaluation of efficacy and safety for the mTOR inhibitor, temsirolimus in EOC/PPC and explored circulating tumor cells (CTC) and AKT/mTOR/downstream tumor markers.

METHODS

Eligible women with measurable, persistent/recurrent EOC/PPC who had received 1-3 prior regimens were treated with 25mg weekly IV temsirolimus until progression or intolerable toxicity. Primary endpoints were progression-free survival (PFS) ≥6-months, tumor response, and toxicity. CellSearch® system was used to examine CTC, and AKT/mTOR/downstream markers were evaluated by archival tumor immunohistochemistry. Kendall's tau-b correlation coefficient (r) and Cox regression modeling were used to explore marker associations with baseline characteristics and outcome.

RESULTS

Sixty patients were enrolled in a two-stage sequential design. Of 54 eligible and evaluable patients, 24.1% (90% CI 14.9%-38.6%) had PFS ≥6 months (median 3.1 months), 9.3% (90% CI 3.7%-23.4%) experienced a partial response. Grade 3/4 adverse events included metabolic (8), gastrointestinal (8), pain (6), constitutional (5) and pulmonary (4). Suggested associations were between cyclin D1 and PFS ≥6 months, PFS or survival; positive CTC pre-treatment and lack of response; and high CTC expression of M30 and PFS ≥6 months/longer PFS.

CONCLUSIONS

Temsirolimus appears to have modest activity in persistent/recurrent EOC/PPC; however, PFS is just below that required to warrant inclusion in phase III studies in unselected patients. Cyclin D1 as a selection marker and CTC measures merit further study.

Management strategies for recurrent platinum-resistant ovarian cancer

Although ovarian cancer is often a chemosensitive malignancy, patients who are resistant to platinum-based chemotherapy represent a therapeutic challenge. Currently, the only drugs that are US FDA approved to treat this subset of patients are paclitaxel, pegylated liposomal doxorubicin (PLD) and topotecan. The response rates with these agents is in the 10-15% range and overall survival is around 12 months. Other drugs that have shown some activity in platinum-resistant ovarian cancer include the taxane analogues, oral etoposide, pemetrexed and bevacizumab. Unfortunately, randomized phase III trials of second-line chemotherapy in patients with platinum-resistant ovarian cancer have not shown an advantage over existing therapy with respect to progression-free survival or overall survival. The only trial that has reported a significant progression-free survival advantage over standard therapy is a randomized phase II trial of PLD with or without EC145, a folate-linked vinca alkaloid. Final survival results of this trial are pending.