RESUMO
Quantitative systems pharmacology (QSP), an emerging field that entails using modeling and computation to interpret, interrogate, and integrate drug effects spanning from the molecule to the whole organism to forecast treatment outcomes, is expected to enhance the efficiency of drug development. Since late 2017, the U.S. Food and Drug Administration has advocated the use of an analogous approach of model-informed drug development. This review focuses on issues pertaining to nanosized medicines (NP) and the potential utility of QSP to determine NP delivery and residence at extracellular or intracellular targets in vivo. The kinetic processes governing NP disposition and transport, interactions with biologic matrix components, binding and internalization in cells, and intracellular trafficking are determined, sometimes jointly, by NP properties (e.g., dimension, materials, surface charge and modifications, shape, and geometry) and target tissue properties (e.g., perfusion status, vessel pore size and wall thickness, vessel and cell density, composition of extracellular matrix, and void volume fraction). These various determinants, together with the heterogeneous tissue structures and microenvironment factors in solid tumors, lead to environment-, spatial-, and time-dependent changes in NP concentrations that are difficult to predict. Adding to the complexity is the recent discovery that NP surface-coating protein corona, whose composition depends on NP properties and which undergoes continuous evolution with time and local protein environments, is yet another unpredictable variable. Examples are provided to demonstrate the potential utility of QSP-based multiscale modeling to capture the physicochemical and biologic processes in equations to enable computational studies of the key kinetic processes in cancer treatments.
Assuntos
Sistemas de Liberação de Medicamentos , Desenvolvimento de Medicamentos/métodos , Nanoestruturas/administração & dosagem , Animais , Humanos , Modelos Teóricos , Nanomedicina/métodos , Neoplasias/tratamento farmacológico , Farmacologia , Biologia de Sistemas/métodos , Fatores de Tempo , Microambiente TumoralRESUMO
PURPOSE: Survivin inhibits apoptosis and enables tumor cells to escape from therapy induced senescence. High survivin expression is associated with bladder cancer aggressiveness and recurrence. We evaluated whether survivin expression is reduced by siRNA and whether survivin silencing would enhance mitomycin C activity in human RT4 bladder transitional cell tumors in vitro and in vivo. MATERIALS AND METHODS: We assessed the effectiveness of siRNA therapy using 2 newly developed pegylated cationic liposome carriers, PCat and PPCat. Each has a fusogenic lipid to destabilize the endosomal membrane. PPCat further contains paclitaxel to enhance in vivo delivery and transfection of survivin siRNA. In vitro antitumor activity was evaluated by short-term MTT and long-term clonogenicity cytotoxicity assays. In vivo intravenous therapy was assessed in mice bearing subcutaneous tumors. RESULTS: Nontarget siRNA showed no antitumor activity in vitro or in vivo. Treatment of cultured cells with mitomycin C at a 50% cytotoxic concentration enhanced survivin mRNA and protein levels. Adding PPCat or PCat containing survivin siRNA reversed survivin induction and enhanced mitomycin C activity (p <0.05). In tumor bearing mice single agent mitomycin C delayed tumor growth and almost tripled the survivin protein level in residual tumors. Adding PPCat-survivin siRNA, which alone resulted in a minor survivin decrease of less than 10%, completely reversed mitomycin C induced survivin and enhanced mitomycin C activity (p <0.05). CONCLUSIONS: Results indicate that there is effective in vivo survivin silencing and synergism between mitomycin C and PPCat-survivin siRNA. This combination represents a potentially useful chemo-gene therapy for bladder cancer.
Assuntos
Antibióticos Antineoplásicos/uso terapêutico , Carcinoma de Células de Transição/tratamento farmacológico , Proteínas Inibidoras de Apoptose/antagonistas & inibidores , Mitomicina/uso terapêutico , Interferência de RNA , RNA Interferente Pequeno/farmacologia , RNA Interferente Pequeno/uso terapêutico , Animais , Carcinoma de Células de Transição/genética , Feminino , Xenoenxertos , Humanos , Injeções Intravenosas , Camundongos , Camundongos Nus , Survivina , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Although conventional treatment of dogs with osteosarcoma (OSA) by amputation and chemotherapy results in reported survival times (STs) of 262-413 days, no major improvements in STs have occurred in the past 2 decades. Suramin is a polysulfonated napthylurea, which at noncytotoxic concentrations in vitro, increases tumor sensitivity to chemotherapy, including doxorubicin. The study authors evaluated the combination of noncytotoxic suramin and doxorubicin after amputation in dogs with OSA. The hypothesis was that treatment of dogs with appendicular OSA with amputation, adjuvant doxorubicin, and noncytotoxic suramin would be well tolerated and result in STs at least comparable to those of doxorubicin alone. Forty-seven dogs received 6.75 mg/kg of suramin IV followed by 30 mg/m(2) of doxorubicin IV 4 hr later. Treatment was repeated q 2 wk for five doses. The median disease free time (DFI) was 203 days (range, 42-1,580+ days) and the median ST for all dogs was 369 days (range, 92-1,616+ days). There was no statistical difference in ST and DFI between greyhounds and nonngreyhounds. Adjuvant doxorubicin and noncytotoxic suramin was well tolerated in dogs with OSA following amputation. Additional studies are needed to determine if this combination treatment protocol provides additional clinical benefit compared with doxorubicin alone.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Neoplasias Ósseas/veterinária , Doenças do Cão/tratamento farmacológico , Osteossarcoma/veterinária , Amputação Cirúrgica/veterinária , Animais , Neoplasias Ósseas/tratamento farmacológico , Quimioterapia Adjuvante/veterinária , Doenças do Cão/cirurgia , Cães , Doxorrubicina/administração & dosagem , Osteossarcoma/tratamento farmacológico , Suramina/administração & dosagem , Análise de Sobrevida , Resultado do TratamentoRESUMO
PURPOSE: We have noted that inadequate drug delivery to tumor cells is a major cause of failed intravesical therapy for nonmuscle invading bladder cancer, partly due to the dilution of drug concentration by urine production during treatment. To address this problem we developed gelatin nanoparticles of paclitaxel designed to yield constant drug concentrations. The hypothesis that a constant, therapeutic concentration in urine, bladder tissue and tumors can be attained was evaluated in dogs. MATERIALS AND METHODS: We studied drug release from paclitaxel gelatin nanoparticles in culture medium in vitro. In vivo studies were performed in tumor-free dogs and in pet dogs with naturally occurring transitional cell carcinoma, in which the pharmacokinetics of paclitaxel gelatin nanoparticles were determined in plasma, urine and tumors. RESULTS: Paclitaxel release from paclitaxel gelatin nanoparticles in vitro and in vivo was rate limited by the drug solubility in aqueous medium. This property yielded constant drug concentrations independent of changes in urine volume during the 2-hour treatment. Intravesical paclitaxel gelatin nanoparticles showed low systemic absorption, and favorable bladder tissue/tumor targeting and retention properties with pharmacologically active concentrations retained in tumors for at least 1 week. CONCLUSIONS: Constant drug release from paclitaxel gelatin nanoparticles may overcome the problem of drug dilution by newly produced urine and the sustained drug levels in tumors may decrease treatment frequency.
Assuntos
Antineoplásicos Fitogênicos/administração & dosagem , Carcinoma de Células de Transição/tratamento farmacológico , Sistemas de Liberação de Medicamentos , Nanopartículas , Paclitaxel/administração & dosagem , Neoplasias da Bexiga Urinária/tratamento farmacológico , Administração Intravesical , Animais , Cães , Gelatina , Humanos , Células Tumorais CultivadasRESUMO
The clinical development of siRNA cancer therapeutics is limited by the poor interstitial transport and inefficient transfection in solid tumors. We have shown that paclitaxel pretreatment, by inducing apoptosis, causes expansion of the interstitial space and thereby improves nanoparticle delivery and transport in tumor interstitium (referred to as paclitaxel tumor priming) and efficacy of nanomedicines in tumor-bearing animals. The present study evaluated whether paclitaxel tumor priming improves the delivery and transfection of siRNA in 2- and 3-dimensional cultures of human oropharyngeal carcinoma FaDu cells. We used the fluorescent siGLO and confocal microcopy to monitor transport, and used survivin siRNA and immunostaining and immunoblotting to monitor transfection. Survivin is a chemoresistance gene/protein, inducible by chemotherapy. siRNA was loaded in cationic liposomes. The results showed that pretreatment with 50-200 nM paclitaxel (24 or 48 h before siRNA) enhanced the total uptake of siGLO into monolayers (â¼15%, p < 0.05), and the depth of penetration into 3-dimensional spheroids and tumor fragment histocultures (2.1- to 2.5-times greater area under the penetration-depth curve). In both monolayer cells and histocultures, paclitaxel pretreatment induced survivin upregulation (p < 0.05). Survivin siRNA alone decreased the survivin levels in a dose-dependent manner, and applying survivin siRNA after paclitaxel pretreatment completely abolished the paclitaxel-induced survivin increases. These findings indicate that paclitaxel tumor priming did not compromise the siRNA functionality. In summary, paclitaxel tumor priming improved the penetration, transfection and functionality of siRNA in tumors, thus offering a promising and practical means to develop chemo-siRNA cancer gene therapy.
Assuntos
Antineoplásicos/farmacologia , Neoplasias/metabolismo , Paclitaxel/farmacologia , RNA Interferente Pequeno/administração & dosagem , Transfecção/métodos , Linhagem Celular Tumoral , Humanos , Lipossomos/química , Nanopartículas/química , RNA Interferente Pequeno/químicaRESUMO
Mathematical modeling has been an important tool in pharmaceutical research for 50 + years and there is increased emphasis over the last decade on using modeling to improve the efficiency and effectiveness of drug development. In an earlier commentary, we applied a multiscale model linking 6 scales (whole body, tumor, vasculature, cell, spatial location, time), together with literature data on nanoparticle and tumor properties, to demonstrate the effects of nanoparticle particles on systemic disposition. The current commentary used a 4-scale model (cell membrane, intracellular organelles, spatial location, time) together with literature data on the intracellular processing of membrane receptors and transporters to demonstrate disruption of transporter homeostasis can lead to drug-drug interaction (DDI) between victim drug (VD) and perpetrator drug (PD), including changes in the area-under-concentration-time-curve of VD in cells that are considered significant by the US Food and Drug Administration (FDA). The model comprised 3 computational components: (a) intracellular transporter homeostasis, (b) pharmacokinetics of extracellular and intracellular VD/PD concentrations, and (c) pharmacodynamics of PD-induced stimulation or inhibition of an intracellular kinetic process. Model-based simulations showed that (a) among the five major endocytic processes, perturbation of transporter internalization or recycling led to the highest incidence and most extensive DDI, with minor DDI for perturbing transporter synthesis and early-to-late endosome and no DDI for perturbing transporter degradation and (b) three experimental conditions (spatial transporter distribution in cells, VD/PD co-incubation time, extracellular PD concentrations) were determinants of DDI detection. We propose modeling is a useful tool for hypothesis generation and for designing experiments to identify potential DDI; its application further aligns with the model-informed drug development paradigm advocated by FDA.
Assuntos
Desenvolvimento de Medicamentos/métodos , Interações Medicamentosas , Transportador 1 de Ânion Orgânico Específico do Fígado/metabolismo , Modelos Biológicos , Membro 1B3 da Família de Transportadores de Ânion Orgânico Carreador de Soluto/metabolismo , Área Sob a Curva , Simulação por Computador , Hepatócitos/metabolismo , Homeostase , HumanosRESUMO
Exosomes, naturally occurring vesicles secreted by cells, are undergoing development as drug carriers. We used experimental and computational studies to investigate the kinetics of intracellular exosome processing and exosome-mediated drug efflux and the effects of exosome inhibition. The experiments used four human-breast or ovarian cancer cells, a cytotoxic drug paclitaxel (PTX), two exosome inhibitors (omeprazole (OME), which inhibits exosome release, and GW4869 (GW), which inhibits synthesis of sphingolipid ceramide required for exosome formation), LC-MS/MS analysis of PTX levels in exosomes, and confocal microscopic study of endocytic transport (monitored using fluorescent nanoparticles and endocytic organelle markers). In all four cells, exosome production was enhanced by PTX but diminished by OME or GW (p < 0.05); the PTX enhancement was completely reversed by OME or GW. Co-treatment with OME or GW simultaneously reduced PTX amount in exosomes and increased PTX amount and cytotoxicity in exosome-donor cells (corresponding to >2-fold synergy as indicated by curve shift and uncertainty envelope analyses). This synergy is consistent with the previous reports that OME co-administration significantly enhances the taxane activity in tumor-bearing mice and in patients with triple negative metastatic breast cancer. The experimental results were used to develop a quantitative pharmacology model; model simulations revealed the different effects of the two exosome inhibitors on intracellular PTX processing and subcellular distribution.
RESUMO
Cancers originating from organs in the peritoneal cavity (e.g., ovarian, pancreatic, colorectal, gastric and liver) account for approximately 250,000 new cancer cases annually in the USA. Peritoneal metastases are common owing to locoregional spread and distant metastases of extraperitoneal cancers. A logical treatment is intraperitoneal therapy, as multiple studies have shown significant targeting advantage for this treatment, including significant survival benefits in stage III, surgically debulked ovarian cancer patients. However, the clinical use of intraperitoneal therapy has been limited, in part, by toxicity, owing to the use of indwelling catheters or high drug exposure, by inadequate drug penetration into bulky tumors (>1 cm) and by the lack of products specifically designed and approved for intraperitoneal treatments. This article provides an overview on the background of peritoneal metastasis, clinical research on intraperitoneal therapy, the pharmacokinetic basis of drug delivery in intraperitoneal therapy and our development of drug-loaded tumor-penetrating microparticles.
Assuntos
Antineoplásicos/administração & dosagem , Antineoplásicos/farmacocinética , Infusões Parenterais/métodos , Neoplasias Peritoneais/tratamento farmacológico , Animais , Portadores de Fármacos , HumanosRESUMO
Approval of generic drugs by the US Food and Drug Administration (FDA) requires the product to be pharmaceutically equivalent to the reference listed drug (RLD) and demonstrate bioequivalence (BE) in effectiveness when administered to patients under the conditions in the RLD product labeling. Effectiveness is determined by drug exposure at the target sites. However, since such measurement is usually unavailable, systemic exposure is assumed to equal target site exposure and systemic BE to equal target site BE. This assumption, while it often applies to small molecule drug products that are readily dissolved in biological fluids and systemically absorbed, is unlikely to apply to nanotechnology products (NP) that exist as heterogeneous systems and are subjected to dimension- and material-dependent changes. This commentary provides an overview of the intersecting and spatial-dependent processes and variables governing the delivery and residence of oncologic NP in solid tumors. In order to provide a quantitative perspective of the collective effects of these processes, we used quantitative systems pharmacology (QSP) multi-scale modeling to capture the physicochemical and biological events on several scales (whole-body, organ/suborgan, cell/subcellular, spatial locations, time). QSP is an emerging field that entails using modeling and computation to facilitate drug development; an analogous approach (i.e., model-informed drug development) is advocated by to FDA. The QSP model-based simulations illustrated that small changes in NP attributes (e.g., size variations during manufacturing, interactions with proteins in biological milieu) could lead to disproportionately large differences in target site exposure, rending systemic BE unlikely to equal target site BE.
Assuntos
Antineoplásicos/administração & dosagem , Aprovação de Drogas , Portadores de Fármacos/farmacocinética , Medicamentos Genéricos/farmacocinética , United States Food and Drug Administration/normas , Antineoplásicos/farmacocinética , Humanos , Nanopartículas , Neoplasias/tratamento farmacológico , Tamanho da Partícula , Equivalência Terapêutica , Distribuição Tecidual , Estados Unidos , United States Food and Drug Administration/legislação & jurisprudênciaRESUMO
Intraperitoneal chemotherapy prolongs survival of ovarian cancer patients, but its utility is limited by treatment-related complications and inadequate drug penetration in larger tumors. Previous intraperitoneal therapy used the paclitaxel/Cremophor EL (polyethoxylated castor oil) formulation designed for intravenous use. The present report describes the development of paclitaxel-loaded microparticles designed for intraperitoneal treatment (referred to as tumor-penetrating microparticles or TPM). Evaluation of TPM was performed using intraperitoneal metastatic, human ovarian SKOV3 xenograft tumor models in mice. TPM were retained in the peritoneal cavity and adhered to tumor surface. TPM consisted of two biocompatible and biodegradable polymeric components with different drug release rates; one component released the drug load rapidly to induce tumor priming, whereas the second component provided sustained drug release. Tumor priming, by expanding interstitial space, promoted transport and penetration of particulates in tumors. These combined features resulted in the following advantages over paclitaxel/Cremophor EL: greater tumor targeting (16-times higher and more sustained concentration in omental tumors), lower toxicity to intestinal crypts and less body weight loss, greater therapeutic efficacy (longer survival and higher cure rate), and greater convenience (less frequent dosing). TPM may overcome the toxicities and compliance-related problems that have limited the utility of intraperitoneal therapy.
Assuntos
Sistemas de Liberação de Medicamentos/métodos , Neoplasias Ovarianas/tratamento farmacológico , Paclitaxel/administração & dosagem , Animais , Antineoplásicos Fitogênicos/administração & dosagem , Antineoplásicos Fitogênicos/toxicidade , Preparações de Ação Retardada , Portadores de Fármacos/química , Portadores de Fármacos/farmacocinética , Feminino , Humanos , Injeções Intraperitoneais , Cinética , Camundongos , Neoplasias Ovarianas/patologia , Paclitaxel/toxicidade , Resultado do Tratamento , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
BACKGROUND: The role of basic fibroblast growth factor (bFGF) in chemoresistance is controversial; some studies showed a relationship between higher bFGF level and chemoresistance while other studies showed the opposite finding. The goal of the present study was to quantify bFGF levels in archived tumor tissues, and to determine its relationship with chemosensitivity. METHODS: We established an image analysis-based method to quantify and convert the immunostaining intensity of intra-tumor bFGF to concentrations; this was accomplished by generating standard curves using human xenograft tumors as the renewable tissue source for simultaneous image analysis and ELISA. The relationships between bFGF concentrations and tumor chemosensitivity of patient tumors (n = 87) to paclitaxel were evaluated using linear regression analysis. RESULTS: The image analysis results were compared to our previous results obtained using a conventional, semi-quantitative visual scoring method. While both analyses indicated an inverse relationship between bFGF level and tumor sensitivity to paclitaxel, the image analysis method, by providing bFGF levels in individual tumors and therefore more data points (87 numerical values as opposed to four groups of staining intensities), further enabled the quantitative analysis of the relationship in subgroups of tumors with different pathobiological properties. The results show significant correlation between bFGF level and tumor sensitivity to the antiproliferation effect, but not the apoptotic effect, of paclitaxel. We further found stronger correlations of bFGF level and paclitaxel sensitivity in four tumor subgroups (high stage, positive p53 staining, negative aFGF staining, containing higher-than-median bFGF level), compared to all other groups. These findings suggest that the relationship between intra-tumoral bFGF level and paclitaxel sensitivity was context-dependent, which may explain the previous contradictory findings on the merit of using plasma or urine bFGF level as a prognostic indicator. CONCLUSION: The present study established a quantitative image analysis method that enabled the measurement of intratumoral bFGF level in archived tissues. The ability to quantify a potential biomarker provided the opportunity to study the relationship between the biomarker and chemosensitivity in tumor subgroups and thereby enabled hypothesis generation for additional translational research.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Biomarcadores Tumorais/análise , Resistencia a Medicamentos Antineoplásicos , Fator 2 de Crescimento de Fibroblastos/análise , Processamento de Imagem Assistida por Computador/métodos , Paclitaxel/farmacologia , Animais , Proliferação de Células/efeitos dos fármacos , Ensaio de Imunoadsorção Enzimática , Feminino , Células HT29 , Humanos , Imuno-Histoquímica , Concentração Inibidora 50 , Masculino , Camundongos , Camundongos SCID , Neoplasias Pancreáticas/patologia , Neoplasias Faríngeas/patologia , Neoplasias da Próstata/patologia , Sensibilidade e Especificidade , Estatística como Assunto , Técnicas de Cultura de Tecidos , Células Tumorais Cultivadas/efeitos dos fármacos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
PURPOSE: To evaluate a computational approach that incorporates experimental data in preclinical models to depict doxorubicin human tissue pharmacokinetics. EXPERIMENTAL DESIGN: Beagle dogs were given 2 mg/kg doxorubicin as i.v. bolus, 4-h infusion, or 96-h infusion. Concentrations in plasma, prostate (target tissue), heart (toxicity), and major tissues for disposition were determined and modeled. Model parameters were obtained after the bolus injection with model validation based on the 4-h and 96-h infusion data. Clinical pharmacokinetic data and scale-up gave doxorubicin profiles in human prostate and heart. RESULTS: In agreement with in vitro results, tissues were best modeled with two compartments, one rapidly and one slowly equilibrating. The developed tissue distribution model predicted concentrations for all three administration regimens well, with an average deviation of 34% (median, 29%). Interspecies scale-up to humans showed that the change from a bolus injection to a slow, 96-h infusion (a) had different effects on the drug partition and accumulation in heart and prostate, and (b) lowered the peak concentration in the plasma by approximately 100-fold but had relatively little effect on maximal heart concentration ( approximately 33% lower). The simulated drug exposure in a human prostate was above the exposure required to inhibit tumor proliferation but was 30 to 50 times below that needed for cell death. CONCLUSION: The present study shows a computation-based paradigm for translating in vitro and in vivo preclinical data and to estimate and compare the drug delivery and pharmacokinetics in target tissues after different treatment schedules.
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Doxorrubicina/administração & dosagem , Doxorrubicina/farmacocinética , Sistemas de Liberação de Medicamentos , Modelos Biológicos , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/metabolismo , Animais , Antibióticos Antineoplásicos/administração & dosagem , Antibióticos Antineoplásicos/farmacocinética , Simulação por Computador , Cães , Esquema de Medicação , Humanos , MasculinoRESUMO
RNA Interference (RNAi) is a potentially useful tool to correct the detrimental effects of faulty genes; several RNAi are undergoing clinical evaluation in various diseases. The present study identified the relative contributions of three mechanisms by which polyanion drugs reduced the gene silencing activity of Lipoplex, a complex of small interfering RNA (siRNA) and cationic liposomes. The study used a siRNA against the chemoresistance gene survivin and two model polyanion drugs (suramin, heparin). Products of Lipoplex destabilization were separated, identified, and/or quantified using ultrafiltration, gel electrophoresis, and RT-qPCR (quantitative reverse transcription polymerase chain reaction). Cell binding and endocytosis of fluorescence-labeled Lipoplex and the amount of siRNA at its site of action RISC (RNA-induced silencing complex) were evaluated using endocytosis markers, confocal microscopy, quantitative image analysis, immunoprecipitation, and RT-qPCR. The results show suramin and heparin exerted multiple concentration-dependent effects. First, these agents altered several Lipoplex properties (i.e., reduced particle size, changed surface charge, modified composition of protein biocorona). Second, both caused Lipoplex destabilization to release double- and single-strand siRNA and/or smaller siRNA-lipid complexes with reduced siRNA cargo. Third, both prevented the cell surface binding and internalization of Lipoplex, diminished the siRNA concentration in RISC, and retarded the mRNA knockdown. Suramin and heparin yielded qualitatively and quantitatively different results. Analysis of the experimental results of suramin using quantitative pharmacology (QP) modeling indicated the major cause of gene silencing activity loss depended on drug concentration, changing from inhibition of endocytosis at lower concentration (accounting for 60% loss at ~9µM) to inhibition of cell surface binding and loss of siRNA cargo at higher concentrations (accounting for 64% and 27%, respectively, at 70µM). In summary, the present study demonstrates the complex and dynamic interactions between polyanions and Lipoplex, and the use of QP modeling to delineate the contributions of three mechanisms to the eventual loss of gene silencing activity.
Assuntos
Heparina/administração & dosagem , RNA Interferente Pequeno/administração & dosagem , Suramina/administração & dosagem , Survivina/genética , Disponibilidade Biológica , Inativação Gênica , Células HT29 , Humanos , Lipossomos , TransfecçãoRESUMO
BACKGROUND: Commonly used methods for analyzing interactivity between drugs (e.g. synergy, antagonism) such as isobologram, combination index, and curve shift are based on the Loewe Additivity principle of dose equivalence and the inherent assumption of similar concentration- effect (C-E) including parallel curves and equal maximum effects (Emax), and therefore are not suitable for drugs with dissimilar C-E. This study describes a new method that is without this limitation and has the additional advantage of enabling statistical analysis. METHODS AND RESULTS: The method comprises two steps. First, based on the dose equivalence principle, the experimentally obtained C-E of one drug was used to calculate the equally effective C-E of the other drug at no interactivity; the resulting two zero-interactivity C-E formed the upper and lower boundaries of Additivity Envelope. Next, 95% confidence intervals calculated from experimental data were added to Additivity Envelope to obtain Uncertainty Envelope (UE). Experimentally observed effects of drug combinations (C-Ecomb,observed) located within UE indicate additivity whereas C-Ecomb,observed located above or below UE indicate statistically significant (p<0.05) synergy or antagonism, respectively. Additional in silico studies demonstrated the shape and size of Additivity Envelope, which determines the ability to detect drug interactivity, depended on the Drug A-to-B concentration ratios and the ratios of their C-E curve shape parameter. Analyses of experimental results of combinations of drugs with nonparallel C-E and/or unequal Emax indicated UE as more versatile and provided more information, compared to earlier methods. CONCLUSION: UE is a broadly applicable method for analysis, including statistical significance assessment, of drug interactivity.
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Interações Medicamentosas , Preparações Farmacêuticas/administração & dosagem , Linhagem Celular Tumoral , Simulação por Computador , Relação Dose-Resposta a Droga , HumanosRESUMO
PURPOSE: Acute graft-versus-host disease (aGVHD) is a major complication of allogeneic bone marrow transplantation. In steroid-refractory aGVHD, mortality is very high. Pentostatin, a potent inhibitor of adenosine deaminase, induces lymphocyte apoptosis and may be useful in the treatment of this condition. PATIENTS AND METHODS: We have conducted a phase I dose escalation study of pentostatin in patients with steroid-refractory aGVHD. Twenty-three patients were enrolled. Starting dose was 1 mg/m2/d by intravenous injection for 3 days. RESULTS: The maximum tolerated dose was found to be 1.5 mg/m2/d. Late infections at the 2-mg/m2/d dose level were believed to be dose limiting toxicities. Lymphopenia was universal, but the neutrophil count was generally not affected. Fevers associated with neutropenia were not observed. Otherwise, the drug was well tolerated, with only modest elevations of liver function tests and thrombocytopenia, each being observed in a single patient. Twenty-two patients were assessable for response, including 14 complete responses (63%) and three partial responses (13%). Median survival after therapy for the group was 85 days (range, 5 to 1,258 days). CONCLUSION: The suggested intravenous dose for a phase II study will be 1.5 mg/m2/d for 3 days. Pentostatin has activity in patients with steroid-refractory aGVHD that is worth exploring in future trials.
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Doença Enxerto-Hospedeiro/tratamento farmacológico , Imunossupressores/uso terapêutico , Pentostatina/uso terapêutico , Doença Aguda , Adolescente , Adulto , Apoptose , Transplante de Medula Óssea , Criança , Pré-Escolar , Relação Dose-Resposta a Droga , Feminino , Neoplasias Hematológicas/terapia , História do Século XVI , Humanos , Imunossupressores/administração & dosagem , Imunossupressores/efeitos adversos , Lactente , Infusões Intravenosas , Linfócitos , Masculino , Dose Máxima Tolerável , Pessoa de Meia-Idade , Pentostatina/administração & dosagem , Pentostatina/efeitos adversos , Transplante Homólogo , Resultado do TratamentoRESUMO
PURPOSE: The present study evaluated the tissue distribution and targeting advantage of intraprostatic chemotherapy. EXPERIMENTAL DESIGN: We studied the delivery and spatial distribution of a fluorescent drug, doxorubicin, in the prostate of beagle dogs, after intraprostatic or i.v. administration. Drug concentrations were measured using high-performance liquid chromatography and confocal fluorescence microscopy. RESULTS: I.v. and intraprostatic injections yielded qualitatively and quantitatively different doxorubicin distribution in the prostate. A relatively homogeneous distribution was found after i.v. administration, whereas intraprostatic injection yielded a highly heterogeneous distribution with >10-fold higher concentrations localized in a cone-shaped glandular lobule bound by fibromuscular stroma, compared with other parts of the prostate. Compared with i.v. injection, intraprostatic injection yielded, on average, approximately 100-fold higher tissue-to-plasma concentration ratio, ranging from 963-fold near the injection site to 19-fold in the contralateral half of the prostate. The drug distribution within the prostate further suggests an important role for acinar flow in intraprostatic drug transport. CONCLUSIONS: Intraprostatic administration represents a viable option to deliver high drug concentrations within the prostate. The results further suggest the fibromuscular stroma separating the prostatic lobules as a major barrier to drug transport and convective flow as an important drug transport mechanism in the prostate.
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Antibióticos Antineoplásicos/farmacocinética , Doxorrubicina/farmacocinética , Próstata/metabolismo , Animais , Antibióticos Antineoplásicos/administração & dosagem , Transporte Biológico , Cães , Doxorrubicina/administração & dosagem , Doxorrubicina/sangue , Infusões Intravenosas , Linfonodos/metabolismo , Masculino , Microscopia de Fluorescência , Modelos Biológicos , Próstata/efeitos dos fármacos , Distribuição TecidualRESUMO
BACKGROUND: Low and nontoxic concentrations (10-50 microM) of suramin, which is a nonspecific inhibitor of multiple growth factors, including fibroblast growth factors, enhances the activities of cytotoxic chemotherapeutic agents, such as doxorubicin and paclitaxel, both in vitro and in vivo. Suramin has not been evaluated as a chemosensitizing agent in dogs with cancer. HYPOTHESIS: Nontoxic suramin can be used safely as a chemosensitizer in dogs. ANIMALS: Sixteen dogs of various breeds with measurable tumors were treated; 1 dog that had undergone amputation for osteosarcoma received adjuvant therapy. METHODS: The dogs received 53 courses of treatment with suramin in combination with doxorubicin. The suramin dosage was 6.75 mg/kg IV 3 h before standard doxorubicin administration every 2 weeks. The pharmacokinetics and clinical efficacy were determined. RESULTS: The pharmacokinetics of low-dose suramin followed a 2-compartment model with half-lives of 2 h and 6 days. The distribution volume was a 0.34 +/- 0.12 L/kg, and clearance was 1.86 +/- 0.76 mL/kg/h. During the time interval that doxorubicin was present at therapeutically active concentrations (ie, from the start of infusion to 24 hours), the plasma concentrations were maintained within 20% of the target range (8-60 microM) in 72% of the treatments. The toxicity of the suramin/doxorubicin combination was mild and comparable to the toxicity expected for doxorubicin monotherapy. Objective partial responses were observed in 2 out of 16 evaluable dogs (13%). All 5 dogs that previously received doxorubicin showed improved responses to the suramin/doxorubicin combination. CONCLUSIONS AND CLINICAL IMPORTANCE: A fixed, low-dose suramin regimen yields the desired target plasma concentrations in most dogs, and appears to enhance the activity of doxorubicin without enhancing toxicity.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Doenças do Cão/tratamento farmacológico , Neoplasias/tratamento farmacológico , Neoplasias/veterinária , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/farmacocinética , Cães , Doxorrubicina/administração & dosagem , Doxorrubicina/efeitos adversos , Sinergismo Farmacológico , Feminino , Masculino , Neoplasias/sangue , Neutropenia/induzido quimicamente , Neutropenia/veterinária , Contagem de Plaquetas/veterinária , Suramina/administração & dosagem , Suramina/efeitos adversos , Suramina/sangue , Suramina/farmacocinética , Trombocitopenia/induzido quimicamente , Trombocitopenia/veterináriaRESUMO
Telomeres, which are important for maintaining chromosome integrity and functions, shorten with each cell division. Telomerase, responsible for telomere synthesis, is expressed in approximately 90% of human tumor cells but seldom in normal somatic cells. This study evaluated the hypothesis that simultaneous shortening of telomeres and inhibition of telomerase results in synergistic and tumor-selective cytotoxicity. In telomerase-positive human pharynx FaDu tumor cells, paclitaxel caused telomere erosion (first detected at 1 h) and apoptosis. Expression of antisense to the RNA component of human telomerase (hTR) inhibited telomerase activity, shortened telomere length, reduced cell growth rate, and resulted in a significant higher sensitivity to paclitaxel. Another telomerase inhibitor, 3'-azido-3'-deoxythymidine (AZT), at a concentration that produced little or no cell detachment or apoptosis, inhibited the telomerase activity and enhanced the paclitaxel-induced cell detachment and apoptosis. AZT also enhanced the activity of paclitaxel in mice bearing well-established s.c. FaDu xenograft tumors (i.e., reduced residual tumor size, enhanced apoptotic cell fraction, and prolonged survival time), without enhancing host toxicity. In contrast, AZT did not enhance the paclitaxel activity in the telomerase-negative osteosarcoma Saos-2 cells nor in FaDu cells where telomerase was already suppressed by antisense hTR, confirming that the AZT effect in parent FaDu cells is mediated through telomerase inhibition. These results demonstrate that combined use of agents targeting both telomere and telomerase yielded synergistic activity selective for tumors that depend on telomerase for telomere maintenance.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Paclitaxel/farmacologia , Neoplasias Faríngeas/genética , Neoplasias Faríngeas/terapia , RNA Antissenso/administração & dosagem , Telomerase/antagonistas & inibidores , Telômero/efeitos dos fármacos , Zidovudina/farmacologia , Animais , Terapia Combinada , Sinergismo Farmacológico , Humanos , Hibridização in Situ Fluorescente , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Osteossarcoma/tratamento farmacológico , Osteossarcoma/enzimologia , Osteossarcoma/genética , Paclitaxel/administração & dosagem , Neoplasias Faríngeas/tratamento farmacológico , Neoplasias Faríngeas/enzimologia , RNA Antissenso/genética , Telomerase/genética , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto , Zidovudina/administração & dosagemRESUMO
Advances in molecular medicine have led to identification of worthy cellular and molecular targets located in extracellular and intracellular compartments. Effectiveness of cancer therapeutics is limited in part by inadequate delivery and transport in tumor interstitium. Parts I and II of this report give an overview on the kinetic processes in delivering therapeutics to their intended targets, the transport barriers in tumor microenvironment and extracellular matrix (TME/ECM), and the experimental approaches to overcome such barriers. Part III discusses new concepts and findings concerning nanoparticle-biocorona complex, including the effects of TME/ECM. Part IV outlines the challenges in animal-to-human translation of cancer nanotherapeutics. Part V provides an overview of the background, current status, and the roles of TME/ECM in immune checkpoint inhibition therapy, the newest cancer treatment modality. Part VI outlines the development and use of multiscale computational modeling to capture the unavoidable tumor heterogeneities, the multiple nonlinear kinetic processes including interstitial and transvascular transport and interactions between cancer therapeutics and TME/ECM, in order to predict the in vivo tumor spatiokinetics of a therapeutic based on experimental in vitro biointerfacial interaction data. Part VII provides perspectives on translational research using quantitative systems pharmacology approaches.