TEMOZOLOMIDE AND BEVACIZUMAB THERAPY IN ADVANCED HEMANGIOPERICYTOMA/ SOLITARY FIBROUS TUMOR

Tumors comprising the spectrum of hemangiopericytoma/ malignant solitary fibrous tumor (HPC/SFT) are thought to arise from fibroblasts and represent a small subset of soft tissue sarcomas. Surgery is typically the treatment of choice for localized disease, with reported 10-year overall survival rates of 54-89% after complete surgical resection. However, for the approximately 20% of HPC/SFT patients who eventually develop local recurrences and/or distant metastases, options for effective treatment are limited and are poorly defined. Alternative therapeutic options are therefore needed for improved palliation and disease control. We hypothesize that HPC/SFT are a spectrum of soft tissue tumors with unique clinical, pathological, and molecular makeup and clinical behavior. HPC/SFT respond to unique therapeutic agents that specifically target aberrations specific to these tumors. We retrospectively reviewed the characteristics and the clinical outcomes for all HPC/SFT patients whose tumor specimens have been reviewed at the MD Anderson Cancer Center from January 1993 to June 2007 by a MD Anderson pathologist and were treated at the institution with available electronic medical records. We identified 128 patients, 79 with primary localized disease and 49 with recurrent and/or metastatic disease. For the 23 patients with advanced HPC/SFT who received adriamycin-based, gemcitabine based, or paclitaxel chemotherapy as first- or second-line therapy, the overall RECIST response rate was 0%. Most patients achieved a brief duration of disease stabilization on chemotherapy, with median progression-free survival (PFS) period of 4.6 months. For the 14 patients with advanced HPC/SFT who received temozolomide and bevacizumab systemic therapy, the overall RECIST response rate was 14%, with the overall Choi response rate of 79%. The median PFS for the cohort was 9.7 months with a median 6-month progression free rate of 78.6%. The most frequently observed toxic effect of temzolomide-bevacizumab therapy was myelosuppression. We have designed a phase II study to evaluate the safety and efficacy of temozolomide-bevaciumab in locally advanced, recurrent, and metastatic HPC/SFT in a prospective manner. Combination therapy with temozolomide and bevacizumab may be a potentially clinically beneficial regimen for advanced HPC/SFT patients.

ATM Signaling to TSC2: Mechanisms and Implications for Cancer Therapy

Ataxia telangiectasia mutated (ATM) is a critical component of the cellular response to DNA damage, where it acts as a damage sensor, and signals to a large network of proteins which execute the important tasks involved in responding to the damage, namely inducing cell cycle checkpoints, inducing DNA repair, modulating transcriptional responses, and regulating cell death pathways if the damage cannot be repaired faithfully. We have now discovered that an additional novel component of this ATM-dependent damage response involves induction of autophagy in response to oxidative stress. In contrast to DNA damage-induced ATM activation however, oxidative stress induced ATM, occurs in the cytoplasm, and does not require nuclear-to-cytoplasmic shuttling of ATM. Using several cell culture systems including MCF7 breast carcinoma cells, SKOV3 ovarian cancer cells, and various lineages of mouse embryonic fibroblasts, we showed that once activated by reactive oxygen species (ROS), ATM signals to mTORC1 to induce autophagy via the LKB1-AMPK-TSC2 pathway. Targeting dysregulation of mTORC1 in Atm-deficient mice, which succumb to lymphomagenesis within 3-4 months of age with daily administration of rapamycin, could significantly extend survival and cause regression of tumors, suggesting that pharmacologically targeting this pathway has therapeutic implications in cancer. We also identified a second contrasting pathway for DNA damage-induced mTORC1 repression which does not require AMPK activation, but does require ATM and TSC2. Several potential mechanisms including mTOR localization and p53-mediated pathways were ruled out however we identified that TSC2 may be an additional cytoplasmic direct ATM substrate that is engaged in response to DNA damage specifically. Lastly, a study was performed to examine whether autophagy induced by ovarian cancer therapeutics (focusing on cisplatin, since paclitaxel does not induce autophagy in the SKOV3 cell line model we used) plays a role in resistance to therapy since autophagy can play both pro-survival mechanisms or be a mechanism of cell death. Using a genetic approach to knock-down Atg5 expression with shRNA in SKOV3 ovarian carcinoma cells, we compared the cytotoxicity of cisplatin in vector or Atg5 knock-down cells, and demonstrated that autophagy does not play any significant role in the response to cisplatin in this cell line.

New implications of E1A gene therapy in breast and ovarian cancer

A variety of human cancers overexpress the HER-2/neu proto-oncogene. Among patients with breast and ovarian cancers this HER-2/ neu overexpression indicates an unfavorable prognosis, with a shorter overall survival duration and a lower response rate to chemotherapeutic agents. Downregulation of HER-2/neu gene expression in cancer cells through attenuation of HER-2/neu promoter activity is, therefore, an attractive strategy for reversing the transformation phenotype and thus the chemoresistance induced by HER-2/neu overexpression. ^ A viral transcriptional regulator, the adenovirus type 5 E1A (early region 1A) that can repress the HER-2/neu promoter, had been identified in the laboratory of Dr. Mien-Chie Hung. Following the identification of the E1A gene, a series of studies revealed that repression of HER-2/neu by the E1A gene which can act therapeutically as a tumor suppressor gene for HER-2/ neu-overexpressing cancers. ^ The results of these preclinical studies became the basis for a phase I trial for E1A gene therapy among patients with HER-2/neu-overexpressing breast and ovarian cancer. In this dissertation, three primary questions concerned with new implications of E1A gene therapy are addressed: First, could E1A gene therapy be incorporated with conventional chemotherapy? Second, could the E1A gene be delivered systemically to exert an anti-tumor effect? And third, what is the activity of the E1A gene in low-HER-2/neu-expressing cancer cells? ^ With regard to the first question, the studies reported in this dissertation have shown that the sensitivity of HER-2/neu-overexpressing breast and ovarian cancer to paclitaxel is in fact enhanced by the downregulation of HER-2/neu overexpression by E1A. With regard to the second question, studies have shown that the E1A gene can exert anti-tumor activity by i.v. injection of the E1A gene complexed with the novel cationic liposome/protamine sulfate/DNA type I (LPDI). And with regard to the third question, the studies of low-HER-2/ neu-expressing breast and ovarian cancers reported here have shown that the E1A gene does in fact suppress metastatic capability. It did not, however, suppress the tumorigenicity. ^ Three conclusions can be drawn from the experimental findings reported in this dissertation. Combining paclitaxel with E1A gene therapy may expand the implications of the gene therapy in the future phase II clinical trial. Anti-tumor activity at a distant site may be achieved with the i.v. injection of the E1A gene. Lastly when administered therapeutically the anti-metastatic effect of the E1A gene in low-HER-2/neu-expressing breast cancer cells may prevent metastasis in primary breast cancer. (Abstract shortened by UMI.)^

Revascularisation versus medical treatment in patients with stable coronary artery disease: network meta-analysis

OBJECTIVE To investigate whether revascularisation improves prognosis compared with medical treatment among patients with stable coronary artery disease. DESIGN Bayesian network meta-analyses to combine direct within trial comparisons between treatments with indirect evidence from other trials while maintaining randomisation. ELIGIBILITY CRITERIA FOR SELECTING STUDIES A strategy of initial medical treatment compared with revascularisation by coronary artery bypass grafting or Food and Drug Administration approved techniques for percutaneous revascularization: balloon angioplasty, bare metal stent, early generation paclitaxel eluting stent, sirolimus eluting stent, and zotarolimus eluting (Endeavor) stent, and new generation everolimus eluting stent, and zotarolimus eluting (Resolute) stent among patients with stable coronary artery disease. DATA SOURCES Medline and Embase from 1980 to 2013 for randomised trials comparing medical treatment with revascularisation. MAIN OUTCOME MEASURE All cause mortality. RESULTS 100 trials in 93 553 patients with 262 090 patient years of follow-up were included. Coronary artery bypass grafting was associated with a survival benefit (rate ratio 0.80, 95% credibility interval 0.70 to 0.91) compared with medical treatment. New generation drug eluting stents (everolimus: 0.75, 0.59 to 0.96; zotarolimus (Resolute): 0.65, 0.42 to 1.00) but not balloon angioplasty (0.85, 0.68 to 1.04), bare metal stents (0.92, 0.79 to 1.05), or early generation drug eluting stents (paclitaxel: 0.92, 0.75 to 1.12; sirolimus: 0.91, 0.75 to 1.10; zotarolimus (Endeavor): 0.88, 0.69 to 1.10) were associated with improved survival compared with medical treatment. Coronary artery bypass grafting reduced the risk of myocardial infarction compared with medical treatment (0.79, 0.63 to 0.99), and everolimus eluting stents showed a trend towards a reduced risk of myocardial infarction (0.75, 0.55 to 1.01). The risk of subsequent revascularisation was noticeably reduced by coronary artery bypass grafting (0.16, 0.13 to 0.20) followed by new generation drug eluting stents (zotarolimus (Resolute): 0.26, 0.17 to 0.40; everolimus: 0.27, 0.21 to 0.35), early generation drug eluting stents (zotarolimus (Endeavor): 0.37, 0.28 to 0.50; sirolimus: 0.29, 0.24 to 0.36; paclitaxel: 0.44, 0.35 to 0.54), and bare metal stents (0.69, 0.59 to 0.81) compared with medical treatment. CONCLUSION Among patients with stable coronary artery disease, coronary artery bypass grafting reduces the risk of death, myocardial infarction, and subsequent revascularisation compared with medical treatment. All stent based coronary revascularisation technologies reduce the need for revascularisation to a variable degree. Our results provide evidence for improved survival with new generation drug eluting stents but no other percutaneous revascularisation technology compared with medical treatment.

Long-Term Comparison of Everolimus-Eluting and Biolimus-Eluting Stents in All-Comer Patients

AIMS: Second-generation everolimus-eluting stents (EES) are safer and more efficient than first-generation paclitaxel-eluting stents (PES). Third-generation biolimus-eluting stents (BES) have been found to be non-inferior to PES. To date, there is no available comparative study between EES and BES. We aimed to investigate the safety and efficacy of BES with biodegradable polymer compared to EES with durable polymer at a follow-up of two years in an unselected population of consecutively enrolled patients. METHODS AND RESULTS: A group of 814 consecutive patients undergoing percutaneous coronary intervention (PCI) was enrolled between 2007 and 2010, of which 527 were treated with EES and 287 with BES implantation. Clinical outcome was compared in 200 pairs using propensity score matching. The primary endpoint was a composite of death, myocardial infarction (MI) and target vessel revascularisation (TVR) at two-year follow-up. Median follow-up was 22 months. The primary outcome occurred in 11.5% of EES and 10.5% of BES patients (HR 1.11, 95% CI: 0.61-2.00, p=0.74). At two years, there was no significant difference with regard to death (HR 0.49, 95% CI: 0.18-1.34, p=0.17), cardiac death (HR 0.14, 95% CI: 0.02-1.14, p=0.66) or MI (HR 6.10, 95% CI: 0.73-50.9, p=0.10). Stent thrombosis (ST) incidence was evenly distributed between EES (n=2) and BES (n=2) (p-value=1.0). CONCLUSIONS: This first clinical study failed to demonstrate any significant difference regarding safety or efficacy between these two types and generations of drug-eluting stents (DES).

Comparison of everolimus- and biolimus-eluting stents with everolimus-eluting bioresorbable vascular scaffold stents: study protocol of the randomized controlled EVERBIO II

BACKGROUND: Second-generation everolimus-eluting stents (EES) and third generation biolimus-eluting stents (BES) have been shown to be superior to first-generation paclitaxel-eluting stents (PES) and second-generation sirolimus-eluting stents (SES). However, neointimal proliferation and very late stent thrombosis is still an unresolved issue of drug-eluting stent (DES) implantation overall. The Absorb™ (Abbott Vascular, Abbott Park, IL, USA) is the first CE approved DES with a bioresorbable vascular scaffold (BVS) thought to reduce long-term complication rates. The EVERBIO II trial was set up to compare the BVS safety and efficacy with both EES and BES in all patients viable for inclusion. METHODS/DESIGN: The EVERBIO II trial is a single-center, assessor-blinded, randomized trial. The study population consists of all patients aged≥18 years old undergoing percutaneous coronary intervention. Exclusion criterion is where the lesion cannot be treated with BVS (reference vessel diameter>4.0 mm). A total of 240 patients will be enrolled and randomly assigned into 3 groups of 80 with either BVS, EES or BES implantation. All patients will undergo a follow-up angiography study at 9 months. Clinical follow-up for up to 5 years will be conducted by telephone. The primary endpoint is in-segment late lumen loss at 9 months measured by quantitative coronary angiography. Secondary endpoints are patient-oriented major adverse cardiac event (MACE) (death, myocardial infarction and target-vessel revascularization), device-oriented MACE (cardiac death, myocardial infarction and target-lesion revascularization), stent thrombosis according to ARC and binary restenosis at follow-up 12 months angiography. DISCUSSION: EVERBIO II is an independent, randomized study, aiming to compare the clinical efficacy, angiographic outcomes and safety of BVS, EES and BES in all comer patients. TRIAL REGISTRATION: The trial listed in clinicaltrials.gov as NCT01711931.

Designed cell penetrating peptide dendrimers efficiently internalize cargo into cells

Redesigning linear cell penetrating peptides (CPPs) into a multi-branched topology with short dipeptide branches gave cell penetrating peptide dendrimers (CPPDs) with higher cell penetration, lower toxicity and hemolysis and higher serum stability than linear CPPs. Their use is demonstrated by delivering a cytotoxic peptide and paclitaxel into cells.

Stent thrombosis in early-generation drug-eluting stents versus newer-generation everolimus-eluting stent assorted by LVEF.

OBJECTIVE Everolimus drug-eluting stents (EES) are superior to early-generation drug-eluting stents (DES), releasing sirolimus (SES) or paclitaxel (PES) in preventing stent thrombosis (ST). Since an impaired LVEF seems to increase the risk of ST, we aimed to investigate the difference in outcome of patients with varying LVEF using EES versus early-generation DES. METHODS In a prospective cohort study, we compared the risk of ST in patients in three LVEF subgroups: normal (LVEF >50%), mildly impaired (LVEF >40% and ≤50%) and moderate-severely impaired (LVEF ≤40%). Within these various LVEF groups, we compared EES with SES and PES after adjustment for baseline differences. RESULTS We assessed a cohort of 5363 patients, with follow-up of up to 4 years and available LVEF. Overall definite ST occurred in 123 (2.3%) patients. ST rates were higher in the LVEF moderate-severely impaired group compared with the normal LVEF group (2.8% vs 2.1%; HR 1.82; CI 1.10 to 3.00). Especially early ST (EST) was more frequent in the moderate-severely impaired LVEF group (HR 2.20; CI 1.06 to 4.53). Overall rates of definite ST were lower in patients using EES compared with patients using SES or PES in all LVEF groups. Interaction terms were not statistically significant. ST rates were higher in the moderate-severely impaired LVEF group compared with the normal LVEF group when using SES or PES, but not significantly different when using EES. CONCLUSIONS EES was associated with a lower risk of definite ST compared with early-generation DES. This lower risk was independent of LVEF, even though ST rates were higher in patients with a moderate-severely impaired LVEF. TRIAL REGISTRATION NO MEC-2013-262.

The association between in-stent neoatherosclerosis and native coronary artery disease progression: a long-term angiographic and optical coherence tomography cohort study.

AIMS The purpose of the present study was to investigate the relationship between in-stent neoatherosclerosis (NA) and native atherosclerosis progression of untreated coronary segments. METHODS AND RESULTS In-stent NA was assessed by optical coherence tomography (OCT) among patients included in the SIRTAX-LATE OCT study 5 years after drug-eluting stent (DES) (sirolimus-eluting and paclitaxel-eluting stents) implantation. Neoatherosclerosis was defined as the presence of fibroatheroma or fibrocalcific plaque within the neointima of stented segments with a longitudinal extension >1.0 mm. Atherosclerosis progression in untreated native coronary segments was evaluated by serial quantitative coronary angiography (QCA). The change in minimal lumen diameter (MLD) was serially assessed within matched segments at baseline and 5-year angiographic follow-up. The key clinical endpoint was non-target lesion (non-TL) revascularization throughout 5 years. A total of 88 patients with 88 lesions were available for OCT analysis 5 years after DES implantation. In-stent NA was observed in 16% of lesions with the majority of plaques being fibroatheromas (11.4%) followed by fibrocalcific plaques (5.7%). A total of 704 non-TL segments were serially evaluated by QCA. Between baseline and 5-year follow-up, the reduction in MLD was significantly more pronounced in patients with NA (-0.25 mm, 95% CI -0.36 to -0.17 mm) when compared with patients without NA (-0.13 mm, 95% CI -0.17 to -0.10 mm, P = 0.002). Similarly, non-TL revascularization was more frequent in patients with NA (78.6%) when compared with patients without NA (44.6%, P = 0.028) throughout 5 years. CONCLUSIONS In-stent NA is more common among patients with angiographic and clinical evidence of native atherosclerosis progression suggesting similar pathophysiological mechanisms.SIRTAX trial is registered at http://www.clinicaltrials.gov/ct2/show/NCT00617084.

Percutaneous coronary interventional strategies for treatment of in-stent restenosis: a network meta-analysis.

BACKGROUND Percutaneous coronary intervention (PCI) with drug-eluting stents is the standard of care for treatment of native coronary artery stenoses, but optimum treatment strategies for bare metal stent and drug-eluting stent in-stent restenosis (ISR) have not been established. We aimed to compare and rank percutaneous treatment strategies for ISR. METHODS We did a network meta-analysis to synthesise both direct and indirect evidence from relevant trials. We searched PubMed, the Cochrane Library Central Register of Controlled Trials, and Embase for randomised controlled trials published up to Oct 31, 2014, of different PCI strategies for treatment of any type of coronary ISR. The primary outcome was percent diameter stenosis at angiographic follow-up. This study is registered with PROSPERO, number CRD42014014191. FINDINGS We deemed 27 trials eligible, including 5923 patients, with follow-up ranging from 6 months to 60 months after the index intervention. Angiographic follow-up was available for 4975 (84%) of 5923 patients 6-12 months after the intervention. PCI with everolimus-eluting stents was the most effective treatment for percent diameter stenosis, with a difference of -9·0% (95% CI -15·8 to -2·2) versus drug-coated balloons (DCB), -9·4% (-17·4 to -1·4) versus sirolimus-eluting stents, -10·2% (-18·4 to -2·0) versus paclitaxel-eluting stents, -19·2% (-28·2 to -10·4) versus vascular brachytherapy, -23·4% (-36·2 to -10·8) versus bare metal stents, -24·2% (-32·2 to -16·4) versus balloon angioplasty, and -31·8% (-44·8 to -18·6) versus rotablation. DCB were ranked as the second most effective treatment, but without significant differences from sirolimus-eluting (-0·2% [95% CI -6·2 to 5·6]) or paclitaxel-eluting (-1·2% [-6·4 to 4·2]) stents. INTERPRETATION These findings suggest that two strategies should be considered for treatment of any type of coronary ISR: PCI with everolimus-eluting stents because of the best angiographic and clinical outcomes, and DCB because of its ability to provide favourable results without adding a new stent layer. FUNDING None.

Three-year efficacy and safety of new- versus early-generation drug-eluting stents for unprotected left main coronary artery disease insights from the ISAR-LEFT MAIN and ISAR-LEFT MAIN 2 trials.

BACKGROUND In percutaneous coronary intervention (PCI) patients new-generation drug-eluting stent (DES) has reduced adverse events in comparison to early-generation DES. The aim of the current study was to investigate the long-term clinical efficacy and safety of new-generation DES versus early-generation DES for PCI of unprotected left main coronary artery (uLMCA) disease. METHODS The patient-level data from the ISAR-LEFT MAIN and ISAR-LEFT MAIN 2 randomized trials were pooled. The clinical outcomes of PCI patients assigned to new-generation DES (everolimus- or zotarolimus-eluting stent) versus early-generation DES (paclitaxel- or sirolimus-eluting stent) were studied. The primary endpoint was the composite of death, myocardial infarction (MI), target lesion revascularization and stroke (MACCE, major adverse cardiac and cerebrovascular event). RESULTS In total, 1257 patients were available. At 3 years, the risk of MACCE was comparable between patients assigned to new-generation DES or early-generation DES (28.2 versus 27.5 %, hazard ratio-HR 1.03, 95 % confidence intervals-CI 0.83-1.26; P = 0.86). Definite/probable stent thrombosis was low and comparable between new-generation DES and early-generation DES (0.8 versus 1.6 %, HR 0.52, 95 % CI 0.18-1.57; P = 0.25); in patients treated with new-generation DES no cases occurred beyond 30 days. Diabetes increased the risk of MACCE in patients treated with new-generation DES but not with early-generation DES (P interaction = 0.004). CONCLUSIONS At 3-year follow-up, a PCI with new-generation DES for uLMCA disease shows comparable efficacy to early-generation DES. Rates of stent thrombosis were low in both groups. Diabetes significantly impacts the risk of MACCE at 3 years in patients treated with new-generation DES for uLMCA disease. ClinicalTrials.gov Identifiers: NCT00133237; NCT00598637.

Functional differences of beta-tubulin isotypes: A study of microtubule assembly and antimitotic drug resistance

Mammalian cells express 7 β-tubulin isotypes in a tissue specific manner. This has long fueled the speculation that different isotypes carry out different functions. To provide direct evidence for their functional significance, class III, IVa, and VI β-tubulin cDNAs were cloned into a tetracycline regulated expression vector and stably transfected Chinese hamster ovary cell lines expressing different levels of ectopic β-tubulin were compared for effects on microtubule organization, microtubule assembly and sensitivity to antimitotic drugs. It was found that all three isotypes coassembled with endogenous β-tubulin. βVI expression caused distinct microtubule rearrangements including microtubule dissociation from the centrosome and accumulation at the cell periphery; whereas expression of βIII and βVIa caused no observable changes in the interphase microtubule network. Overexpression of all 3 isotypes caused spindle malformation and mitotic defects. Both βIII and βIVa disrupted microtubule assembly in proportion to their abundance and thereby conferred supersensitivity to microtubule depolymerizing drugs. In contrast, βVI stabilized microtubules at low stoichiometry and thus conferred resistance to many microtubule destabilizing drugs but not vinblastine. The 3 isotypes caused differing responses to microtubule stabilizing drugs. Expression of βIII conferred paclitaxel resistance while βVI did not. Low expression of βIVa caused supersensitivity to paclitaxel, whereas higher expression resulted in the loss of supersensitivity. The results suggest that βIVa may possess an enhanced ability to bind paclitaxel that increases sensitivity to the drug and acts substoichiometrically. At high levels of βVIa expression, however, microtubule disruptive effects counteract the assembly promoting pressure exerted by increased paclitaxel binding, and drug supersensitivity is lost. From this study, I concluded that β-tubulin isotypes behave differently from each other in terms of microtubule organization, microtubule assembly and dynamics, and antimitotic drug sensitivity. The isotype composition of cell can impart subtle to dramatic effects on the properties of microtubules leading to potential functional consequences and opening the opportunity to exploit differences in microtubule isotype composition for therapeutic gain. ^

Design, Synthesis and Development of Transporter Targeting Agents for Image-guided Therapy and Drug Delivery

The purpose of this study was to design, synthesize and develop novel transporter targeting agents for image-guided therapy and drug delivery. Two novel agents, N4-guanine (N4amG) and glycopeptide (GP) were synthesized for tumor cell proliferation assessment and cancer theranostic platform, respectively. N4amG and GP were synthesized and radiolabeled with 99mTc and 68Ga. The chemical and radiochemical purities as well as radiochemical stabilities of radiolabeled N4amG and GP were tested. In vitro stability assessment showed both 99mTc-N4amG and 99mTc-GP were stable up to 6 hours, whereas 68Ga-GP was stable up to 2 hours. Cell culture studies confirmed radiolabeled N4amG and GP could penetrate the cell membrane through nucleoside transporters and amino acid transporters, respectively. Up to 40% of intracellular 99mTc-N4amG and 99mTc-GP was found within cell nucleus following 2 hours of incubation. Flow cytometry analysis revealed 99mTc-N4amG was a cell cycle S phase-specific agent. There was a significant difference of the uptake of 99mTc-GP between pre- and post- paclitaxel-treated cells, which suggests that 99mTc-GP may be useful in chemotherapy treatment monitoring. Moreover, radiolabeled N4amG and GP were tested in vivo using tumor-bearing animal models. 99mTc-N4amG showed an increase in tumor-to-muscle count density ratios up to 5 at 4 hour imaging. Both 99mTc-labeled agents showed decreased tumor uptake after paclitaxel treatment. Immunohistochemistry analysis demonstrated that the uptake of 99mTc-N4amG was correlated with Ki-67 expression. Both 99mTc-N4amG and 99mTc-GP could differentiate between tumor and inflammation in animal studies. Furthermore, 68Ga-GP was compared to 18F-FDG in rabbit PET imaging studies. 68Ga-GP had lower tumor standardized uptake values (SUV), but similar uptake dynamics, and different biodistribution compared with 18F-FDG. Finally, to demonstrate that GP can be a potential drug carrier for cancer theranostics, several drugs, including doxorubicin, were selected to be conjugated to GP. Imaging studies demonstrated that tumor uptake of GP-drug conjugates was increased as a function of time. GP-doxorubicin (GP-DOX) showed a slow-release pattern in in vitro cytotoxicity assay and exhibited anti-cancer efficacy with reduced toxicity in in vivo tumor growth delay study. In conclusion, both N4amG and GP are transporter-based targeting agents. Radiolabeled N4amG can be used for tumor cell proliferation assessment. GP is a potential agent for image-guided therapy and drug delivery.

Synergistic inhibition of human cancer cell growth by cytotoxic drugs and mixed backbone antisense oligonucleotide targeting protein kinase A

Protein kinase A type I plays a key role in neoplastic transformation, conveying mitogenic signals of different growth factors and oncogenes. Inhibition of protein kinase A type I by antisense oligonucleotides targeting its RIα regulatory subunit results in cancer cell growth inhibition in vitro and in vivo. A novel mixed backbone oligonucleotide HYB 190 and its mismatched control HYB 239 were tested on soft agar growth of several human cancer cell types. HYB 190 demonstrated a dose-dependent inhibition of colony formation in all cell lines whereas the HYB 239 at the same doses caused a modest or no growth inhibition. A noninhibitory dose of each mixed backbone oligonucleotide was used in OVCAR-3 ovarian and GEO colon cancer cells to study whether any cooperative effect may occur between the antisense and a series of cytotoxic drugs acting by different mechanisms. Treatment with HYB 190 resulted in an additive growth inhibitory effect with several cytotoxic drugs when measured by soft agar colony formation. A synergistic growth inhibition, which correlated with increased apoptosis, was observed when HYB 190 was added to cancer cells treated with taxanes, platinum-based compounds, and topoisomerase II selective drugs. This synergistic effect was also observed in breast cancer cells and was obtained with other related drugs such as docetaxel and carboplatin. Combination of HYB 190 and paclitaxel resulted in an accumulation of cells in late S-G2 phases of cell cycle and marked induction of apoptosis. A cooperative effect of HYB 190 and paclitaxel was also obtained in vivo in nude mice bearing human GEO colon cancer xenografts. These results are the first report of a cooperative growth inhibitory effect obtained in a variety of human cancer cell lines by antisense mixed backbone oligonucleotide targeting protein kinase A type I-mediated mitogenic signals and specific cytotoxic drugs.

Fibroblast growth factors: An epigenetic mechanism of broad spectrum resistance to anticancer drugs

Based on the observation that removal of tumors from metastatic organs reversed their chemoresistance, we hypothesized that chemoresistance is induced by extracellular factors in tumor-bearing organs. By comparing chemosensitivity and proteins in different tumors (primary vs. metastases) and different culture systems (tumor fragment histocultures vs. monolayer cultures derived from the same tumor), we found elevated levels of acidic (aFGF) and basic (bFGF) fibroblast growth factors in the conditioned medium (CM) of solid and metastatic tumors. These CM induced broad spectrum resistance to drugs with diverse structures and action mechanisms (paclitaxel, doxorubicin, 5-fluorouracil). Inhibition of bFGF by mAb and its removal by immunoprecipitation resulted in complete reversal of the CM-induced chemoresistance, whereas inhibition/removal of aFGF resulted in partial reversal. Using CM that had been depleted of aFGF and/or bFGF and subsequently reconstituted with respective human recombinant proteins, we found that bFGF but not aFGF induced chemoresistance whereas aFGF amplified the bFGF effect. aFGF and bFGF fully accounted for the CM effect, indicating these proteins as the underlying mechanism of the chemoresistance. The FGF-induced resistance was not due to reduced intracellular drug accumulation or altered cell proliferation. We further showed that an inhibitor of aFGF/bFGF (suramin) enhanced the in vitro and in vivo activity of chemotherapy, resulting in shrinkage and eradication of well established human lung metastases in mice without enhancing toxicity. These results indicate elevated levels of extracellular aFGF/bFGF as an epigenetic mechanism by which cancer cells elude cytotoxic insult by chemotherapy, and provide a basis for designing new treatment strategies.