Clinical Trials In Cancer Patients Research Articles

Gambogic Acid Is a Tissue-Specific Proteasome Inhibitor In Vitro and In Vivo

Gambogic acid (GA) is a natural compound derived from Chinese herbs that has been approved by the Chinese Food and Drug Administration for clinical trials in cancer patients; however, its molecular targets have not been thoroughly studied. Here, we report that GA inhibits tumor proteasome activity, with potency comparable to bortezomib but much less toxicity. First, GA acts as a prodrug and only gains proteasome-inhibitory function after being metabolized by intracellular CYP2E1. Second, GA-induced proteasome inhibition is a prerequisite for its cytotoxicity and anticancer effect without off-targets. Finally, because expression of the CYP2E1 gene is very high in tumor tissues but low in many normal tissues, GA could therefore produce tissue-specific proteasome inhibition and tumor-specific toxicity, with clinical significance for designing novel strategies for cancer treatment.

Pharmacokinetics of Single Ascending Doses of the P-Glycoprotein Inhibitor Tariquidar in Healthy Subjects

We assessed the pharmacokinetics (PK), tolerability and safety of tariquidar (TQD), a P-glycoprotein (Pgp) inhibitor, after intravenous administration of single ascending doses. Employed doses were up to 4-fold higher than in previous clinical trials in cancer patients and are capable of inhibiting Pgp at the blood-brain barrier. Fifteen male healthy volunteers were randomized to receive single intravenous doses of TQD at 4, 6 or 8 mg/kg body weight and underwent blood sampling for over 24 h. TQD concentrations were determined in plasma samples with high-performance liquid chromatography mass spectrometry. No dose-limiting toxicities of TQD were observed. The area under the plasma concentration-time curve from start until 24 h after the end of infusion was positively correlated with an administered TQD dose (r = 0.8981, p < 0.0001). Moreover, we found a positive correlation for volume of distribution at steady state (r = 0.7129, p = 0.0004) with TQD dose. Dose dependency of volume of distribution at steady state points to non-linear PK of TQD, which was in all likelihood caused by transporter saturation at high TQD doses. Acceptable safety and tolerability as well as dose-linear increases in plasma exposure support the future use of TQD at doses up to 8 mg/kg to inhibit Pgp at the human blood-brain barrier.

Interest in “Smart Bombs” Explodes

Abstract In the wake of last year's approval of brentuximab vedotin for certain lymphomas, and significant improvements in progression-free and overall survival for breast cancer patients in clinical trials of trastuzumab emtansine, companies are ratcheting up development of many more antibody–drug conjugates.

A Critical Review of the Enrollment of Black Patients in Cancer Clinical Trials

Although clinical trials represent a vital opportunity for improvements in cancer treatment, data show that a small proportion of patients with newly diagnosed cancer participate in clinical research. Black patients continue to have a worse prognosis for most cancers compared with other patients of other races/ethnicities. Racial/ethnic- and age-related disparities in clinical trial accrual are also well documented. The recruitment and retention of minorities in these trials present an even greater challenge despite regulatory efforts and initiatives to increase representation. Treatment data from homogenous populations prevent us from understanding therapeutic response and the true safety profile of novel therapies. Patient-, physician-, and system-level factors that affect trial participation have been extensively studied. However, years of accrual data remain largely unchanged, suggesting the challenge lies in effectively addressing these factors. Furthermore, data showing that black patients tend to have more advanced stage cancers at the time of diagnosis in fact beg their overrepresentation on clinical trials. An inability to successfully enroll diverse populations in clinical trials only exacerbates racial/ethnic differences in cancer treatment and survivorship.

Zentrenbildung beim Maximalversorger - Katalysator der Kommunikation

The number of patients with a diagnosis of cancer is alarming: according to new figures from the Robert Koch Institute about 435 000 patients are diagnosed annually in Germany. 210 000 patients die annually of this diagnosis. Even if no significant progress in prevention has been achieved, in 2020 about 25 % more cases will be diagnosed. In the last two decades it has become established that an interdisciplinary treatment of tumour patients is necessary because the variety of different treatment options depending on an individual person cannot be mastered by one physician. The goal of the centres and certification is to establish a very concentrated expertise in large case numbers and quality-assured transparent treatment. The central requirement of a maximum-care centre is thus to enable communication under appropriate conditions. Promoting not only the space requirements, centre must also develop a treatment corridor and is responsible for further education. Additionally an oncology centre has a goal in communications, namely, to offer a treatment option for all patients in each stage of the disease, and to incorporate cancer patients in clinical trials.

Rash to mTOR inhibitor everolimus: Systematic review and meta-analysis.

e19624 Background: Everolimus is an mTOR inhibitor approved for treatment of renal cell carcinoma, subependymal giant cell astrocytoma, and progressive neuroendocrine tumors of pancreatic origin. Its use may be hindered due to adverse events, including rash. The reported incidence and risk of rash to everolimus varies widely and has not been closely investigated. Therefore, we conducted a systematic review and meta-analysis of the literature to determine the incidence and risk of developing rash. Methods: We searched PubMed and Web of Science databases and abstracts presented at the American Society of Clinical Oncology from 1998 to July 2011 using the keyword “everolimus” to identify relevant clinical trials. Eligible studies included prospective phase II and phase III clinical trials of cancer patients on 10 mg of everolimus daily with available data on incidence of rash. The summary incidence and relative risk (RR) of rash were calculated using either the random-effects or fixed-effects model, depending on the heterogeneity of the constituent studies. Results: A total of 2,242 patients with various malignancies from 13 clinical trials were included in the analysis. The summary incidences of all-grade and high-grade rash in patients on everolimus were28.6% (95% CI: 20.8 – 38.0) and 1.0% (95% CI: 0.6 – 1.7), respectively. Everolimus was associated with a statistically significant increased risk of all-grade rash (RR=3.853, 95% CI: 2.470 – 6.013, p=0.000), but the RR for high-grade rash (RR= 2.997, 95% CI: 0.633 – 14.185) was not statistically significant, with a p value of 0.166. Conclusions: Everolimus is associated with a significant risk of developing rash. Management of rash to everolimus is critical to prevent dose modifications and decreased quality of life, both of which can negatively affect clinical outcomes.

Strategies to Use Immune Modulators in Therapeutic Vaccines Against Cancer

Cancers so much resemble self that they prove difficult for the immune system to eliminate, and those that have already escaped natural immunosurveillance have gotten past the natural immune barriers to malignancy. A successful therapeutic cancer vaccine must overcome these escape mechanisms. Our laboratory has focused on a multistep "push-pull" approach in which we combine strategies to overcome each of the mechanisms of escape. If tumor epitopes are insufficiently immunogenic, we increase their immunogenicity by epitope enhancement, improving their binding affinity to major histocompatibility complex (MHC) molecules. If the anti-tumor response is too weak or of the wrong phenotype, we use cytokines, costimulatory molecules, Toll-like receptor ligands, and other molecular adjuvants to increase not only the quantity of the response but also its quality, to push the response in the right direction. Finally, the tumor invokes multiple immunosuppressive mechanisms to defend itself, so we need to overcome those as well, including blocking or depleting regulatory cells or inhibiting regulatory molecules, to pull the response by removing the brakes. Some of these strategies individually have now been translated into human clinical trials in cancer patients. Combinations of these in a push-pull approach are promising for the successful immunotherapy of cancer.

A Pilot Study of a Culturally Targeted Video Intervention to Increase Participation of African American Patients in Cancer Clinical Trials

Barriers to clinical trial participation among African American cancer patients are well characterized in the literature. Attitudinal barriers encompassing fear, distrust, and concerns about ethical misconduct are also well documented. To increase trial accrual, these attitudes must be adequately addressed, yet there remains a lack of targeted interventions toward this end. We developed a 15-minute culturally targeted video designed to impact six specific attitudes of African American cancer patients toward therapeutic trials. We conducted a pilot study to test in the first such intervention to increase intention to enroll. The primary study outcome was self-reported likelihood to participate in a therapeutic trial. Using a mixed methods approach, we developed the Attitudes and Intention to Enroll in Therapeutic Clinical Trials (AIET) instrument, a 30-item questionnaire measuring six attitudinal barriers to African American trial participation. We enrolled 108 eligible active treatment patients at a large urban cancer institute. McNemar's test for matched pairs was used to assess changes in attitudes and likelihood to enroll in a clinical trial at baseline and immediately after the video. Pre- and post-video AIET summative scores were analyzed by paired t-test for each attitudinal barrier. Patients' likelihood of enrolling in a clinical trial significantly increased post-video with 36% of the sample showing positive changes in intention [McNemar's χ(2) = 33.39, p < .001]. Paired t-tests showed significant changes in all six attitudinal barriers measured via AIET summative scores from pre- to post-video. These data suggest utility of our video for increasing African American participation in clinical trials.

A Pilot Study of a Culturally Targeted Video Intervention to Increase Participation of African American Patients in Cancer Clinical Trials

Abstract Purpose. Barriers to clinical trial participation among African American cancer patients are well characterized in the literature. Attitudinal barriers encompassing fear, distrust, and concerns about ethical misconduct are also well documented. To increase trial accrual, these attitudes must be adequately addressed, yet there remains a lack of targeted interventions toward this end. We developed a 15-minute culturally targeted video designed to impact six specific attitudes of African American cancer patients toward therapeutic trials. We conducted a pilot study to test in the first such intervention to increase intention to enroll. Patients and Methods. The primary study outcome was self-reported likelihood to participate in a therapeutic trial. Using a mixed methods approach, we developed the Attitudes and Intention to Enroll in Therapeutic Clinical Trials (AIET) instrument, a 30-item questionnaire measuring six attitudinal barriers to African American trial participation. We enrolled 108 eligible active treatment patients at a large urban cancer institute. McNemar's test for matched pairs was used to assess changes in attitudes and likelihood to enroll in a clinical trial at baseline and immediately after the video. Pre- and post-video AIET summative scores were analyzed by paired t-test for each attitudinal barrier. Results. Patients' likelihood of enrolling in a clinical trial significantly increased post-video with 36% of the sample showing positive changes in intention [McNemar's χ2 = 33.39, p &amp;lt; .001]. Paired t-tests showed significant changes in all six attitudinal barriers measured via AIET summative scores from pre- to post-video. Conclusion. These data suggest utility of our video for increasing African American participation in clinical trials.

Discovery of PG545: A Highly Potent and Simultaneous Inhibitor of Angiogenesis, Tumor Growth, and Metastasis

Increasing the aglycone lipophilicity of a series of polysulfated oligosaccharide glycoside heparan sulfate (HS) mimetics via attachment of a steroid or long chain alkyl group resulted in compounds with significantly improved in vitro and ex vivo antiangiogenic activity. The compounds potently inhibited heparanase and HS-binding angiogenic growth factors and displayed improved antitumor and antimetastatic activity in vivo compared with the earlier series. Preliminary pharmacokinetic analyses also revealed significant increases in half-life following iv dosing, ultimately supporting less frequent dosing regimens in preclinical tumor models compared with other HS mimetics. The compounds also displayed only mild anticoagulant activity, a common side effect usually associated with HS mimetics. These efforts led to the identification of 3β-cholestanyl 2,3,4,6-tetra-O-sulfo-α-d-glucopyranosyl-(1→4)-2,3,6-tri-O-sulfo-α-d-glucopyranosyl-(1→4)-2,3,6-tri-O-sulfo-α-d-glucopyranosyl-(1→4)-2,3,6-tri-O-sulfo-β-d-glucopyranoside, tridecasodium salt (PG545, 18) as a clinical candidate. Compound 18 was recently evaluated in a phase I clinical trial in cancer patients.

Activation of Natural Killer T Cells Promotes M2 Macrophage Polarization in Adipose Tissue and Improves Systemic Glucose Tolerance via Interleukin-4 (IL-4)/STAT6 Protein Signaling Axis in Obesity

Natural killer T (NKT) cells are important therapeutic targets in various disease models and are under clinical trials for cancer patients. However, their function in obesity and type 2 diabetes remains unclear. Our data show that adipose tissues of both mice and humans contain a population of type 1 NKT cells, whose abundance decreases with increased adiposity and insulin resistance. Although loss-of-function of NKT cells had no effect on glucose tolerance in animals with prolonged high fat diet feeding, activation of NKT cells by lipid agonist α-galactosylceramide enhances alternative macrophage polarization in adipose tissue and improves glucose homeostasis in animals at different stages of obesity. Furthermore, the effect of NKT cells is largely mediated by the IL-4/STAT6 signaling axis in obese adipose tissue. Thus, our data identify a novel therapeutic target for the treatment of obesity-associated inflammation and type 2 diabetes.

Enhancing the anticancer effect of the histone deacetylase inhibitor by activating transglutaminase

Histone deacetylase (HDAC) inhibitors have shown promising anticancer effects in clinical trials. However, a proportion of patients do not respond to HDAC inhibitor therapy. We have previously demonstrated that tissue transglutaminase (TG2) is one of the genes commonly up-regulated by HDAC inhibitors in vitro and in vivo, and that two structurally distinct TG2 protein isoforms, the full-length (TG2-L) and the short form (TG2-S), exert opposing effects on cell differentiation due to difference in transamidation activity. Here we show that the HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) transcriptionally activates the expression of both TG2-L and TG2-S, and that up-regulation of TG2-L renders neuroblastoma cells less sensitive to SAHA-induced cytotoxicity. Combination therapy with SAHA and the transamidation activator Naringenin, a natural product found in citrus fruits, synergistically enhanced transamidation activity and SAHA-induced cytotoxicity in neuroblastoma cells, but not in normal non-malignant cells. In tumour-bearing N-Myc transgenic mice, SAHA and Naringenin synergistically suppressed tumour progression. Taken together, our data demonstrate that SAHA-induced TG2-L over-expression renders cancer cells less sensitive to SAHA therapy, and suggest the addition of Naringenin to SAHA and probably also other HDAC inhibitors in future clinical trials in cancer patients.

The effect of erythropoietin on normal and neoplastic cells

Erythropoietin (Epo) is an essential hormone that binds and activates the Epo receptor (EpoR) resident on the surface of erythroid progenitor cells, thereby promoting erythropoiesis. Recombinant human erythropoietin has been used successfully for over 20 years to treat anemia in millions of patients. In addition to erythropoiesis, Epo has also been reported to have other effects, such as tissue protection and promotion of tumor cell growth or survival. This became of significant concern in 2003, when some clinical trials in cancer patients reported increased tumor progression and worse survival outcomes in patients treated with erythropoiesis-stimulating agents (ESAs). One of the potential mechanisms proffered to explain the observed safety issues was that functional EpoR was expressed in tumors and/or endothelial cells, and that ESAs directly stimulated tumor growth and/or antagonized tumor ablative therapies. Since then, numerous groups have performed further research evaluating this potential mechanism with conflicting data and conclusions. Here, we review the biology of endogenous Epo and EpoR expression and function in erythropoiesis, and evaluate the evidence pertaining to the expression of EpoR on normal nonhematopoietic and tumor cells.

Effects of PPARγ Ligands on Leukemia.

Peroxisome proliferator-activated receptors (PPARs) and retinoic acid receptors (RARs), members of the nuclear receptor superfamily, are transcription factors that regulate a variety of important cellular functions. PPARs form heterodimers retinoid X receptor (RXR), an obligate heterodimeric partner for other nuclear receptors. Several novel links between retinoid metabolism and PPAR responses have been identified, and activation of PPAR/RXR expression has been shown to increase response to retinoids. PPARγ has emerged as a key regulator of cell growth and survival, whose activity is modulated by a number of synthetic and natural ligands. While clinical trials in cancer patients with thiazolidinediones (TZD) have been disappointing, novel structurally different PPARγ ligands, including triterpenoids, have entered clinical arena as therapeutic agents for epithelial and hematopoietic malignancies. Here we shall review the antitumor advances of PPARγ, alone and in combination with RARα ligands in control of cell proliferation, differentiation, and apoptosis and their potential therapeutic applications in hematological malignancies.

The Clinically Active PARP Inhibitor AG014699 Ameliorates Cardiotoxicity but Does Not Enhance the Efficacy of Doxorubicin, despite Improving Tumor Perfusion and Radiation Response in Mice

AG014699 was the first inhibitor of the DNA repair enzyme PARP-1 to enter clinical trial in cancer patients. In addition to enhancing the cytotoxic effect of DNA-damaging chemotherapies, we have previously shown that AG014699 is vasoactive, thereby having the potential to improve drug biodistribution. The effectiveness of the clinical agent doxorubicin is confounded both by poor tumor penetration and cardiotoxicity elicited via PARP hyperactivation. In this study, we analyzed the impact of AG014699 on doxorubicin tolerance and response in breast (MDA-MB-231) and colorectal (SW620, LoVo) tumor models in vitro and in vivo. As anticipated, AG014699 did not potentiate the response to doxorubicin in vitro. In vivo, AG014699 did not influence the pharmacokinetics of doxorubicin; however, it did ameliorate cardiotoxicity. Both toxicity and extent of amelioration were more pronounced in male than in female mice. AG014699 improved vessel perfusion in both MDA-MB-231 and SW620 tumors; however, this neither led to improved tumor-accumulation of doxorubicin nor enhanced therapeutic response. In contrast, when combined with radiotherapy, AG014699 significantly enhanced response both in vitro and in vivo. Real-time assessment of tumor vessel function and companion histologic studies indicate that doxorubicin causes a profound antivascular effect that counters the positive effect of AG014699 on perfusion. These data indicate that although AG014699 can enhance response to some chemotherapeutic drugs via improved delivery, this does not apply to doxorubicin. PARP inhibitors may still be of use to counter doxorubicin toxicity, and if the gender effect translates from rodents to humans, this would have greater effect in males.

Impact on product quality of high productive GS-CHO cell lines

Background The Clinical Program of the Ludwig Institute for Cancer Research (LICR) aims to translate basic laboratory discoveries into early phase clinical trials in cancer patients. A key component of the LICR approach has been to focus on the identification of antibodies selectively targeting antigens preferentially expressed in tumour tissue, and the molecular engineering of chimeric or humanised antibodies to these targets. The development of robust and high producing cell lines is crucial in the development of each antibody construct. The Cell Biology Group at the LICR Melbourne-Austin Branch is responsible for the production of recombinant proteins including monoclonal antibodies from hybridomas or from industrially relevant mammalian cell lines (CHO, NS0, etc). The Cell Line Development activities are driven by the successful combination of industrial relevant cell lines transfected with cancer-relevant DNA targets using the Glutamine-Synthetase system (GS) from Lonza. Here we present two case-studies of high-productive cell lines in terms of product quality and biological activity of the protein produced with these cell lines.

PI3Ks Maintain the Structural Integrity of T-Tubules in Cardiac Myocytes

BackgroundPhosphoinositide 3-kinases (PI3Ks) regulate numerous physiological processes including some aspects of cardiac function. Although regulation of cardiac contraction by individual PI3K isoforms has been studied, little is known about the cardiac consequences of downregulating multiple PI3Ks concurrently.Methods and ResultsGenetic ablation of both p110α and p110β in cardiac myocytes throughout development or in adult mice caused heart failure and death. Ventricular myocytes from double knockout animals showed transverse tubule (T-tubule) loss and disorganization, misalignment of L-type Ca2+ channels in the T-tubules with ryanodine receptors in the sarcoplasmic reticulum, and reduced Ca2+ transients and contractility. Junctophilin-2, which is thought to tether T-tubules to the sarcoplasmic reticulum, was mislocalized in the double PI3K-null myocytes without a change in expression level.ConclusionsPI3K p110α and p110β are required to maintain the organized network of T-tubules that is vital for efficient Ca2+-induced Ca2+ release and ventricular contraction. PI3Ks maintain T-tubule organization by regulating junctophilin-2 localization. These results could have important medical implications because several PI3K inhibitors that target both isoforms are being used to treat cancer patients in clinical trials.

Preclinical Characterization of OSI-027, a Potent and Selective Inhibitor of mTORC1 and mTORC2: Distinct from Rapamycin

The phosphoinositide 3-kinase (PI3K)/AKT/mTOR pathway is frequently activated in human cancers, and mTOR is a clinically validated target. mTOR forms two distinct multiprotein complexes, mTORC1 and mTORC2, which regulate cell growth, metabolism, proliferation, and survival. Rapamycin and its analogues partially inhibit mTOR through allosteric binding to mTORC1, but not mTORC2, and have shown clinical utility in certain cancers. Here, we report the preclinical characterization of OSI-027, a selective and potent dual inhibitor of mTORC1 and mTORC2 with biochemical IC(50) values of 22 nmol/L and 65 nmol/L, respectively. OSI-027 shows more than 100-fold selectivity for mTOR relative to PI3Kα, PI3Kβ, PI3Kγ, and DNA-PK. OSI-027 inhibits phosphorylation of the mTORC1 substrates 4E-BP1 and S6K1 as well as the mTORC2 substrate AKT in diverse cancer models in vitro and in vivo. OSI-027 and OXA-01 (close analogue of OSI-027) potently inhibit proliferation of several rapamycin-sensitive and -insensitive nonengineered and engineered cancer cell lines and also, induce cell death in tumor cell lines with activated PI3K-AKT signaling. OSI-027 shows concentration-dependent pharmacodynamic effects on phosphorylation of 4E-BP1 and AKT in tumor tissue with resulting tumor growth inhibition. OSI-027 shows robust antitumor activity in several different human xenograft models representing various histologies. Furthermore, in COLO 205 and GEO colon cancer xenograft models, OSI-027 shows superior efficacy compared with rapamycin. Our results further support the important role of mTOR as a driver of tumor growth and establish OSI-027 as a potent anticancer agent. OSI-027 is currently in phase I clinical trials in cancer patients.

Matrix metalloproteinases in tumorigenesis: an evolving paradigm.

Proteases are crucial for development, tissue remodeling, and tumorigenesis. Matrix metalloproteinases (MMPs) family, in particular, consists of more than 20 members with unique substrates and diverse function. The expression and activity of MMPs in a variety of human cancers have been intensively studied. MMPs have well-recognized roles in the late stage of tumor progression, invasion, and metastasis. However, increasing evidence demonstrates that MMPs are involved earlier in tumorigenesis, e.g., in malignant transformation, angiogenesis, and tumor growth both at the primary and metastatic sites. Recent studies also suggest that MMPs play complex roles in tumor progression. While most MMPs promote tumor progression, some of them may protect the host against tumorigenesis in a context-dependent manner. MMPs have been chosen as promising targets for cancer therapy on the basis of their aberrant up-regulation in malignant tumors and their ability to promote cancer metastasis. Although preclinical studies testing the efficacy of MMP suppression in tumor models were so encouraging, the results of clinical trials in cancer patients have been rather disappointing. Here, we review the complex roles of MMPs and their endogenous inhibitors such as tissue inhibitors of metalloproteinase in tumorigenesis and strategies in suppressing MMPs.

Casein kinase 2 phosphorylation of Hsp90 threonine 22 modulates chaperone function and drug sensitivity

The molecular chaperone Heat Shock Protein 90 (Hsp90) is essential for the function of various oncoproteins that are vital components of multiple signaling networks regulating cancer cell proliferation, survival, and metastasis. Hsp90 chaperone function is coupled to its ATPase activity, which can be inhibited by natural products such as the ansamycin geldanamycin (GA) and the resorcinol radicicol (RD). These compounds have served as templates for development of numerous natural product Hsp90 inhibitors. More recently, second generation, fully synthetic Hsp90 inhibitors, based on a variety of chemical scaffolds, have also been synthesized. Together, 18 natural product and synthetic Hsp90 inhibitors have entered clinical trial in cancer patients. To successfully develop Hsp90 inhibitors for oncology indications it is important to understand the factors that influence the susceptibility of Hsp90 to these drugs in vivo. We recently reported that Casein Kinase 2 phosphorylates a conserved threonine residue (T22) in helix-1 of the yeast Hsp90 N-domain both in vitro and in vivo. Phosphorylation of this residue reduces ATPase activity and affects Hsp90 chaperone function. Here, we present additional data demonstrating that ATP binding but not N-domain dimerization is a prerequisite for T22 phosphorylation. We also provide evidence that T22 is an important determinant of Hsp90 inhibitor sensitivity in yeast and we show that T22 phosphorylation status contributes to drug sensitivity in vivo.