RESUMO
Intratumoral (IT) therapy is a powerful method of controlling tumor growth, but a major unsolved problem is the rapidity that injected drugs exit tumors, limiting on-target exposure and efficacy. We have developed a generic long acting IT delivery system in which a drug is covalently tethered to hydrogel microspheres (MS) by a cleavable linker; upon injection the conjugate forms a depot that slowly releases the drug and "bathes" the tumor for long periods. We established technology to measure tissue pharmacokinetics and studied MSs attached to SN-38, a topoisomerase 1 inhibitor. When MS ~ SN-38 was injected locally, tissues showed high levels of SN-38 with a long half-life of ~ 1 week. IT MS ~ SN-38 was ~ tenfold more efficacious as an anti-tumor agent than systemic SN-38. We also propose and provide an example that long-acting IT therapy might enable safe use of two drugs with overlapping toxicities. Here, long-acting IT MS ~ SN-38 is delivered with concurrent systemic PARP inhibitor. The tumor is exposed to both drugs whereas other tissues are exposed only to the systemic drug; synergistic anti-tumor activity supported the validity of this approach. We propose use of this approach to increase efficacy and reduce toxicities of combinations of immune checkpoint inhibitors such as αCTLA-4 and αPD-1.
Assuntos
Irinotecano , Animais , Camundongos , Humanos , Irinotecano/administração & dosagem , Irinotecano/farmacocinética , Microesferas , Hidrogéis/química , Linhagem Celular Tumoral , Inibidores da Topoisomerase I/administração & dosagem , Inibidores da Topoisomerase I/farmacocinética , Inibidores da Topoisomerase I/uso terapêutico , Sistemas de Liberação de Medicamentos , Feminino , Neoplasias/tratamento farmacológico , Ensaios Antitumorais Modelo de Xenoenxerto , Injeções Intralesionais , Antineoplásicos/administração & dosagem , Antineoplásicos/farmacocinética , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologiaRESUMO
The tumor uptake of large non-targeted nanocarriers primarily occurs through passive extravasation, known as the enhanced permeability and retention (EPR) effect. Prior studies demonstrated improved tumor uptake and retention of 4-arm 40 kDa star polyethylene glycol (StarPEG) polymers for cancer imaging by adding prostate-specific membrane antigen (PSMA) targeting small molecule ligands. To test PSMA-targeted delivery and therapeutic efficacy, StarPEG nanodrugs with/without three copies of PSMA-targeting ligands, ACUPA, are designed and synthesized. For single-photon emission computed tomography (SPECT) imaging and therapy, each nanocarrier is labeled with 177Lu using DOTA radiometal chelator. The radiolabeled nanodrugs, [177Lu]PEG-(DOTA)1 and [177Lu]PEG-(DOTA)1(ACUPA)3, are evaluated in vitro and in vivo using PSMA+ PC3-Pip and/or PSMA- PC3-Flu cell lines, subcutaneous xenografts and disseminated metastatic models. The nanocarriers are efficiently radiolabeled with 177Lu with molar activities 10.8-15.8 MBq/nmol. Besides excellent in vitro PSMA binding affinity (kD = 51.7 nM), the targeted nanocarrier, [177Lu]PEG-(DOTA)1(ACUPA)3, demonstrated excellent in vivo SPECT imaging contrast with 21.3% ID/g PC3-Pip tumors uptake at 192 h. Single doses of 18.5 MBq [177Lu]PEG-(DOTA)1(ACUPA)3 showed complete resolution of the PC3-Pip xenografts observed up to 138 days. Along with PSMA-targeted excellent imaging contrast, these results demonstrated high treatment efficacy of [177Lu]PEG-(DOTA)1(ACUPA)3 for prostate cancer, with potential for clinical translation.
Assuntos
Glutamato Carboxipeptidase II , Polietilenoglicóis , Neoplasias da Próstata , Tomografia Computadorizada de Emissão de Fóton Único , Masculino , Polietilenoglicóis/química , Animais , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Humanos , Camundongos , Linhagem Celular Tumoral , Glutamato Carboxipeptidase II/metabolismo , Tomografia Computadorizada de Emissão de Fóton Único/métodos , Antígenos de Superfície/metabolismo , Nanopartículas/química , Lutécio/química , Portadores de Fármacos/química , Radioisótopos/química , Distribuição Tecidual , Camundongos Nus , Compostos Heterocíclicos com 1 Anel/químicaRESUMO
Poly(ADP-ribose) polymerase inhibitors (PARPi) have been approved for once or twice daily oral use in the treatment of cancers with BRCA defects. However, for some patients, oral administration of PARPi may be impractical or intolerable, and a long-acting injectable formulation is desirable. We recently developed a long-acting PEGylated PARPi prodrug, PEGâ¼talazoparib (TLZ), which suppressed the growth of PARPi-sensitive tumors in mice for very long periods. However, the release rate of TLZ from the conjugate was too fast to be optimal in humans. We prepared several new PEGâ¼TLZ prodrugs having longer half-lives of drug release and accurately measured their pharmacokinetics in the rat. Using the rates of release of TLZ from these prodrugs and the known pharmacokinetics of free TLZ in humans, we simulated the pharmacokinetics of the macromolecular prodrugs and released TLZ in humans. From several possibilities, we chose two conjugates that could be administered intravenously every 2 weeks and maintain TLZ within its known therapeutic window. We describe situations where the PEGâ¼TLZ conjugates would find utility in humans and suggest how the intravenously administered long-acting prodrugs could in fact be more effective than daily oral administration of free TLZ.
Assuntos
Antineoplásicos , Neoplasias , Pró-Fármacos , Humanos , Camundongos , Ratos , Animais , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Inibidores de Poli(ADP-Ribose) Polimerases/uso terapêutico , Pró-Fármacos/farmacologia , Neoplasias/tratamento farmacológicoRESUMO
We previously proposed that sacituzumab govitecan (SG, Trodelvy®) likely acts as a simple prodrug of systemic SN-38 as well as an antibody drug conjugate (ADC). In the present commentary, we assess whether a long-acting SN-38 prodrug, such as PLX038, might be efficacious in SG-resistant patients. We first describe possible mechanisms of action of SG, with new insights on pharmacokinetics and TROP2 receptor occupancy. We argue that SG is not an optimal conventional ADC and that the amount of systemic SN-38 spontaneously hydrolyzed from the ADC is so high it must have activity. Then, we describe the concept of time-over-target as related to the pharmacology of SG and PLX038 as SN-38 prodrugs. To be clear, we are not in any way suggesting that PLX038 or any SN-38 prodrug is superior to SG as an anticancer agent. Clearly, SG has the benefit over antigen-independent SN-38 prodrugs in that it targets cells with the TROP2 receptor. However, we surmise that PLX038 should be a more efficacious and less toxic prodrug of systemic SN-38 than SG. Finally, we suggest possible mechanisms of SG resistance and how PLX038 might perform in the context of each. Taken together, we argue that-contrary to many opinions-SG does not exclusively act as a conventional ADC, and propose that PLX038 may be efficacious in some settings of SG-resistance.
Assuntos
Anticorpos Monoclonais Humanizados , Camptotecina/análogos & derivados , Imunoconjugados , Neoplasias , Pró-Fármacos , Humanos , Irinotecano/farmacologia , Irinotecano/uso terapêutico , Pró-Fármacos/farmacologia , Pró-Fármacos/uso terapêutico , Antígenos de Neoplasias , Neoplasias/tratamento farmacológico , Imunoconjugados/farmacologia , Imunoconjugados/uso terapêuticoRESUMO
Exatecan (Exa) is a very potent inhibitor of topoisomerase I and anticancer agent. It has been intensively studied as a single agent, a large macromolecular conjugate and as the payload component of antigen-dependent antibody-drug conjugates. The current work describes an antigen-independent conjugate of Exa with polyethylene glycol (PEG) that slowly releases free Exa. Exa was conjugated to a 4-arm 40 kDa PEG through a ß-eliminative cleavable linker. Pharmacokinetic studies in mice showed that the conjugate has an apparent circulating half-life of 12 hours, which reflects a composite of both the rate of renal elimination (half-life â¼18 hours) and release of Exa (half-life â¼40 hours). Remarkably, a single low dose of 10 µmol/kg PEG-Exa-only approximately 0.2 µmol/mouse-caused complete suppression of tumor growth of BRCA1-deficient MX-1 xenografts lasting over 40 days. A single low dose of 2.5 µmol/kg PEG-Exa administered with low but efficacious doses of the PARP inhibitor talazoparib showed strong synergy and caused significant tumor regression. Furthermore, the same low, single dose of PEG-Exa administered with the ATR inhibitor VX970 at doses of the DNA damage response inhibitor that do not affect tumor growth show high tumor regression, strong synergy, and synthetic lethality. Significance: A circulating conjugate that slowly releases Exa is described. It is efficacious after a single dose and synergistic with ATR and PARP inhibitors.
Assuntos
Antineoplásicos , Neoplasias , Humanos , Animais , Camundongos , Camptotecina/farmacologia , Antineoplásicos/farmacologia , Neoplasias/tratamento farmacológico , Polietilenoglicóis/farmacologia , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Dano ao DNARESUMO
Tumoral uptake of large-size nanoparticles is mediated by the enhanced permeability and retention (EPR) effect, with variable accumulation and heterogenous tumor tissue penetration depending on the tumor phenotype. The performance of nanocarriers via specific targeting has the potential to improve imaging contrast and therapeutic efficacy in vivo with increased deep tissue penetration. To address this hypothesis, we designed and synthesized prostate cancer-targeting starPEG nanocarriers (40 kDa, 15 nm), [89Zr]PEG-(DFB)3(ACUPA)1 and [89Zr]PEG-(DFB)1(ACUPA)3, with one or three prostate-specific membrane antigen (PSMA)-targeting ACUPA ligands. The in vitro PSMA binding affinity and in vivo pharmacokinetics of the targeted nanocarriers were compared with a nontargeted starPEG, [89Zr]PEG-(DFB)4, in PSMA+ PC3-Pip and PSMA- PC3-Flu cells, and xenografts. Increasing the number of ACUPA ligands improved the in vitro binding affinity of PEG-derived polymers to PC3-Pip cells. While both PSMA-targeted nanocarriers significantly improved tissue penetration in PC3-Pip tumors, the multivalent [89Zr]PEG-(DFB)1(ACUPA)3 showed a remarkably higher PC3-Pip/blood ratio and background clearance. In contrast, the nontargeted [89Zr]PEG-(DFB)4 showed low EPR-mediated accumulation with poor tumor tissue penetration. Overall, ACUPA conjugated targeted starPEGs significantly improve tumor retention with deep tumor tissue penetration in low EPR PC3-Pip xenografts. These data suggest that PSMA targeting with multivalent ACUPA ligands may be a generally applicable strategy to increase nanocarrier delivery to prostate cancer. These targeted multivalent nanocarriers with high tumor binding and low healthy tissue retention could be employed in imaging and therapeutic applications.
Assuntos
Antígenos de Superfície , Polímeros , Neoplasias da Próstata , Humanos , Masculino , Antígenos de Superfície/metabolismo , Linhagem Celular Tumoral , Glutamato Carboxipeptidase II/metabolismo , Ligantes , Polímeros/uso terapêutico , Próstata/patologia , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/metabolismoRESUMO
Alterations in the ATM gene are among the most common somatic and hereditary cancer mutations, and ATM-deficient tumors are hypersensitive to DNA-damaging agents. A synthetic lethal combination of DNA-damaging agents and DNA repair inhibitors could have widespread utility in ATM-deficient cancers. However, overlapping normal tissue toxicities from these drug classes have precluded their clinical translation. We investigated PLX038, a releasable polyethylene glycol-conjugate of the topoisomerase I inhibitor SN-38, in ATM wild-type and null isogenic xenografts and in a BRCA1-deficient xenograft. PLX038 monotherapy and combination with PARP inhibition potently inhibited the growth of both BRCA1- and ATM-deficient tumors. A patient with an ATM-mutated breast cancer treated with PLX038 and the PARP inhibitor rucaparib achieved rapid, symptomatic, and radiographic complete response lasting 12 months. Single-agent PLX038 or PLX038 in combination with DNA damage response inhibitors are novel therapeutic paradigms for patients with ATM-loss cancers.
Assuntos
Inibidores de Poli(ADP-Ribose) Polimerases , Inibidores da Topoisomerase I , Humanos , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Inibidores de Poli(ADP-Ribose) Polimerases/uso terapêutico , Inibidores da Topoisomerase I/farmacologia , Inibidores da Topoisomerase I/uso terapêutico , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Linhagem Celular Tumoral , Reparo do DNARESUMO
The C-natriuretic peptide (CNP) analog vosoritide has recently been approved for treatment of achondroplasia in children. However, the regimen requires daily subcutaneous injections in pediatric patients over multiple years. The present work sought to develop a long-acting CNP that would provide efficacy equal to or greater than that of vosoritide but require less frequent injections. We used a technology for half-life extension, whereby a drug is attached to tetra-polyethylene glycol hydrogels (tetra-PEG) by ß-eliminative linkers that cleave at predetermined rates. These hydrogels-fabricated as uniform â¼60-µm microspheres-are injected subcutaneously, where they serve as a stationary depot to slowly release the drug into the systemic circulation. We prepared a highly active, stable CNP analog-[Gln6,14]CNP-38-composed of the 38 C-terminal amino acids of human CNP-53 containing Asn to Gln substitutions to preclude degradative deamidation. Two microsphere [Gln6,14]CNP-38 conjugates were prepared, with release rates designed to allow once-weekly and once-monthly administration. After subcutaneous injection of the conjugates in mice, [Gln6,14]CNP-38 was slowly released into the systemic circulation and showed biphasic elimination pharmacokinetics with terminal half-lives of â¼200 and â¼600 h. Both preparations increased growth of mice comparable to or exceeding that produced by daily vosoritide. Simulations of the pharmacokinetics in humans indicated that plasma [Gln6,14]CNP-38 levels should be maintained within a therapeutic window over weekly, biweekly, and likely, monthly dosing intervals. Compared with vosoritide, which requires â¼30 injections per month, microsphere [Gln6,14]CNP-38 conjugates-especially the biweekly and monthly dosing-could provide an alternative that would be well accepted by physicians, patients, and patient caregivers.
Assuntos
Acondroplasia , Desenvolvimento de Medicamentos , Peptídeo Natriurético Tipo C , Acondroplasia/tratamento farmacológico , Animais , Criança , Preparações de Ação Retardada , Humanos , Hidrogéis/química , Injeções Subcutâneas , Camundongos , Microesferas , Peptídeo Natriurético Tipo C/administração & dosagem , Peptídeo Natriurético Tipo C/análogos & derivados , Peptídeo Natriurético Tipo C/síntese química , Peptídeo Natriurético Tipo C/farmacocinéticaRESUMO
ß-Elimination of drugs tethered to macromolecular carbamates provides a platform for drug half-life extension. However, the macromolecular Michael acceptor products formed upon drug release can potentially react with biological amines and thiols and may raise concerns about safety. We desired to mitigate this possibility by developing linkers that have predictable rates of ß-elimination but suppressed rates of nucleophilic addition to their Michael acceptor products. We prepared Michael acceptor products of ß-eliminative linkers that contained a methyl group at the Cß carbon or a gem-dimethyl group at the Cγ carbon and studied the kinetics of their reactions with the most prevalent biological nucleophiles-amine and thiol groups. Aza-Michael reactions with glycine are slowed about 20-fold by methylation of the ß-carbon and 175-fold with a gem-dimethyl group at the γ-carbon. Likewise, addition of the glutathione thiol to γ-gem-dimethyl Michael acceptors was retarded 7-24-fold compared to parent unsubstituted linkers. It was estimated that in an in vivo environment of â¼0.5 mM macromolecular thiols or â¼20 mM macromolecular amines-as in plasma-the reaction half-life of a typical Michael acceptor with a γ-gem-dimethyl linker could exceed 3 years for thiols or 25 years for amines. We also prepared a large series of γ-gem-dimethyl ß-eliminative linkers and showed excellent structure-activity relationships of elimination rates with corresponding unsubstituted parent linkers. Finally, we compared the first-generation unsubstituted and new gem-dimethyl ß-eliminative linkers in a once-monthly drug delivery system of a 39 amino acid peptide. Both linkers provided the desired half-life extension of the peptide, but the Michael acceptor formed from the gem-dimethyl linker was much less reactive. We conclude that the γ-gem-dimethyl ß-eliminative linkers provide high flexibility and greatly reduce potential reactions of Michael acceptor products with biologically important nucleophiles.
Assuntos
Preparações Farmacêuticas/química , Carbamatos/química , Sistemas de Liberação de Medicamentos , Liberação Controlada de Fármacos , Meia-Vida , Cinética , Relação Estrutura-AtividadeRESUMO
PARP inhibitors are approved for treatment of cancers with BRCA1 or BRCA2 defects. In this study, we prepared and characterized a very long-acting PARP inhibitor. Synthesis of a macromolecular prodrug of talazoparib (TLZ) was achieved by covalent conjugation to a PEG40kDa carrier via a ß-eliminative releasable linker. A single injection of the PEGâ¼TLZ conjugate was as effective as â¼30 daily oral doses of TLZ in growth suppression of homologous recombination-defective tumors in mouse xenografts. These included the KT-10 Wilms' tumor with a PALB2 mutation, the BRCA1-deficient MX-1 triple-negative breast cancer, and the BRCA2-deficient DLD-1 colon cancer; the prodrug did not inhibit an isogenic DLD-1 tumor with wild-type BRCA2. Although the half-life of PEGâ¼TLZ and released TLZ in the mouse was only â¼1 day, the exposure of released TLZ from a single safe, effective dose of the prodrug exceeded that of oral TLZ given daily over one month. µPET/CT imaging showed high uptake and prolonged retention of an 89Zr-labeled surrogate of PEGâ¼TLZ in the MX-1 BRCA1-deficient tumor. These data suggest that the long-lasting antitumor effect of the prodrug is due to a combination of its long t 1/2, the high exposure of TLZ released from the prodrug, increased tumor sensitivity upon continued exposure, and tumor accumulation. Using pharmacokinetic parameters of TLZ in humans, we designed a long-acting PEGâ¼TLZ for humans that may be superior in efficacy to daily oral TLZ and would be useful for treatment of PARP inhibitor-sensitive cancers in which oral medications are not tolerated. SIGNIFICANCE: These findings demonstrate that a single injection of a long-acting prodrug of the PARP inhibitor talazoparib in murine xenografts provides tumor suppression equivalent to a month of daily dosing of talazoparib.
Assuntos
Distúrbios no Reparo do DNA/patologia , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Ftalazinas/uso terapêutico , Inibidores de Poli(ADP-Ribose) Polimerases/uso terapêutico , Animais , Antineoplásicos/uso terapêutico , Linhagem Celular Tumoral , Reparo do DNA/efeitos dos fármacos , Reparo do DNA/genética , Distúrbios no Reparo do DNA/tratamento farmacológico , Distúrbios no Reparo do DNA/genética , Preparações de Ação Retardada/uso terapêutico , Feminino , Genes BRCA2 , Genes do Tumor de Wilms , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Nus , Camundongos SCID , Neoplasias/genética , Ftalazinas/química , Polietilenoglicóis/química , Polietilenoglicóis/uso terapêutico , Pró-Fármacos/uso terapêutico , Ensaios Antitumorais Modelo de Xenoenxerto , Zircônio/química , Zircônio/uso terapêuticoRESUMO
The goal was to develop and characterize a companion diagnostic for the releasable PEG40kDaâ¼SN-38 oncology drug, PLX038, that would identify tumors susceptible to high accumulation of PLX038. PEG conjugates of the zirconium ligand desferroxamine B (DFB) of similar size and charge to PLX038 were prepared that contained one or four DFB, as well as one that contained three SN-38 moieties and one DFB. Uptake and associated kinetic parameters of the 89Zr-labeled nanocarriers were determined in tumor and normal tissues in mice using µPET/CT imaging. The data were fit to physiologically based pharmacokinetic models to simulate the mass-time profiles of distribution of conjugates in the tissues of interest. The time-activity curves for normal tissues showed high levels at the earliest time of measurement due to vascularization, followed by a monophasic loss. In tumors, levels were initially lower than in normal tissues but increased to 9% to 14% of injected dose over several days. The efflux half-life in tumors was very long, approximately 400 hours, and tumor levels remained at about 10% injected dose 9 days after injection. Compared with diagnostic liposomes, the PEG nanocarriers have a longer serum half-life, are retained in tumors at higher levels, remain there longer, and afford higher tumor exposure. The small PEG40kDa nanocarriers studied here show properties for passive targeting of tumors that are superior than most nanoparticles and might be effective probes to identify tumors susceptible to similar size therapeutic nanocarriers such as PLX038.
Assuntos
Polietilenoglicóis/uso terapêutico , Tomografia por Emissão de Pósitrons/métodos , Radioisótopos/uso terapêutico , Zircônio/uso terapêutico , Animais , Modelos Animais de Doenças , Humanos , Camundongos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
PURPOSE: The purpose of this study was to determine the importance of UGT1A1 activity on the metabolism and pharmacokinetics of a releasable PEG ~ SN-38 conjugate, PLX038A. Irinotecan (CPT-11) is converted to the topoisomerase 1 inhibitor SN-38 by first-pass hepatic metabolism and is converted to its glucuronide SN-38G by UGT1A1. With diminished UGT1A1 activity, the high liver exposure to SN-38 can cause increased toxicity of CPT-11. In contrast, releasable PEG ~ SN-38 conjugates-such as PLX038-release SN-38 in the vascular compartment, and only low levels of SN-38 are expected to enter the liver by transport through the OATP1B1 transporter. METHODS: We measured CPT-11 and PLX038A metabolites in plasma and bile, and determined pharmacokinetics of PLX038A in UGT1A-deficient and replete rats. RESULTS: Compared to CPT-11, treatment of rats with PLX038A results in very low levels of biliary SN-38 and SN-38G, a low flux through UGT1A, and a low SN-38G/SN-38 ratio in plasma. Further, the pharmacokinetics of plasma PLX038A and SN-38 in rats deficient in UGT1A is unchanged compared to normal rats. CONCLUSIONS: The disposition of PEGylated SN-38 is independent of UGT1A activity in rats, and PLX038 may find utility in full-dose treatment of patients who are UGT1A1*28 homozygotes or have metastatic disease with coincidental or incidental liver dysfunction.
Assuntos
Camptotecina/análogos & derivados , Regulação da Expressão Gênica/efeitos dos fármacos , Glucuronatos/farmacologia , Glucuronosiltransferase/metabolismo , Irinotecano/farmacologia , Polietilenoglicóis/química , Pró-Fármacos/farmacologia , Inibidores da Topoisomerase I/farmacologia , Animais , Bile/metabolismo , Camptotecina/farmacocinética , Camptotecina/farmacologia , Glucuronatos/farmacocinética , Irinotecano/farmacocinética , Fígado/metabolismo , Pró-Fármacos/farmacocinética , Ratos , Ratos Gunn , Distribuição Tecidual , Inibidores da Topoisomerase I/farmacocinéticaRESUMO
PURPOSE: Optimal efficacy of a macromolecular prodrug requires balancing the rate of drug release with the rate of prodrug elimination. Since circulating macromolecules have different elimination rates in different species, a prodrug optimal for one species will likely not be for another. The objectives of this work were (a) to develop an approach to optimize pharmacokinetics of a PEG~SN-38 prodrug in a particular species, (b) to use the approach to predict the pharmacokinetics of various prodrugs of SN-38 in the mouse and human, and (c) to develop a PEG~SN-38 conjugate that is optimized for mouse tumor models. METHODS: We developed models that describe the pharmacokinetics of a drug released from a prodrug by the relationship between the rates of drug release and elimination of the prodrug. We tested the model by varying the release rate of SN-38 from PEG~SN-38 conjugates in the setting of a constant prodrug elimination rate in the mouse. Finally, we tested the antitumor efficacy of a PEG~SN-38 optimized for the mouse. RESULTS: Optimization of a PEG~SN-38 prodrug was achieved by adjusting the rate of SN-38 release such that the ratio of t1/2,ß of released SN-38 to the t1/2 of prodrug elimination was 0.2-0.8. Using this approach, we could rationalize the efficacy of previous PEGylated SN-38 prodrugs in the mouse and human. Finally, a mouse-optimized PEG~SN-38 showed remarkable antitumor activity in BRCA1-deficient MX-1 xenografts; a single dose gave tumor regression, suppression, and shrinkage of massive tumors. CONCLUSIONS: The efficacy of a macromolecular prodrug can be optimized for a given species by balancing the rate of drug release from the carrier with the rate of prodrug elimination.
Assuntos
Liberação Controlada de Fármacos , Irinotecano/farmacocinética , Taxa de Depuração Metabólica , Pró-Fármacos/farmacocinética , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Animais , Antineoplásicos/farmacocinética , Portadores de Fármacos/farmacocinética , Sistemas de Liberação de Medicamentos , Meia-Vida , Substâncias Macromoleculares/farmacocinética , Camundongos , Polietilenoglicóis/farmacologia , Inibidores da Topoisomerase I/farmacocinética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
PURPOSE: The short half lives of small molecules in the vitreous requires frequent repeated intravitreal injections that are impractical for treatment of chronic eye diseases. We sought to develop a method for increasing the intravitreal half-life of small-molecule drugs. METHODS: We adapted a technology for controlled release of drugs from macromolecular carriers for use as a long-acting intravitreal delivery system for small molecules. As a prototype, a small molecule complement factor D inhibitor with an intravitreal half-life of 7 hours was covalently attached to a 4-arm PEG40kDa by a self-cleaving ß-eliminative linker with a cleavage half-life of approximately 1 week. RESULTS: After intravitreal injection in rabbits, the drug was slowly released in the vitreous, and equilibrated with the retina and choroid. The intravitreal half-life of the intact PEG-drug conjugate in the rabbit was 7 days, and that of the released drug was 3.6 days. We simulated the anticipated pharmacokinetics of the delivery system in human vitreous, and estimated that the half-life of a 4-arm PEG40kDa conjugate would be approximately 2 weeks, and that of the released drug would be approximately 5 days. CONCLUSIONS: We posit that a linker with a cleavage half life of 2 weeks would confer a half life of approximately 7 days to a released small molecule drug in humans, comparable to the half life of approved intravitreal injected macromolecular drugs. TRANSLATIONAL RELEVANCE: With this technology, a potent small molecule with an appropriate therapeutic window should be administrable by intravitreal injections in the human at once-monthly intervals.
RESUMO
We have developed a chemically-controlled drug delivery system in which a drug is covalently attached via a carbamate to hydrogel microspheres using a ß-eliminative linker; rate-determining proton removal from a CH bond adjacent to an electron withdrawing group results in a ß-elimination to cleave the carbamate and release the drug. After subcutaneous injection of the hydrogel-drug conjugate, the drug is slowly released into the systemic circulation and acquires an elimination t1/2,ß that matches the t1/2 of linker cleavage. A similar ß-eliminative linker with a slower cleavage rate is installed into crosslinks of the polymer to trigger gel degradation after drug release. We have now prepared ß-eliminative linkers that contain deuterium in place of the hydrogen whose removal initiates cleavage. In vitro model systems of drug release and degelation show large primary deuterium kinetic isotope effects of kH/kDâ¯~â¯2.5 to 3.5. Using a deuterated linker to attach the peptide octreotide to hydrogel-microspheres, the in vivo t1/2,ß of the drug was increased from ~1.5 to 4.5â¯weeks in the rat. Similarly, the in vivo time to biodegradation of hydrogels with deuterium-containing crosslinks could be extended ~2.5-fold compared to hydrogen-containing counterparts. Thus, the use of primary deuterium kinetic isotope effects in a single platform technology can control rates of ß-elimination reactions in drug release and polymer biodegradation rates.
Assuntos
Deutério/química , Sistemas de Liberação de Medicamentos , Octreotida/administração & dosagem , Polímeros/química , Animais , Reagentes de Ligações Cruzadas/química , Portadores de Fármacos/química , Liberação Controlada de Fármacos , Meia-Vida , Hidrogéis , Octreotida/química , Octreotida/farmacocinética , RatosRESUMO
We have developed a chemically controlled very long-acting delivery system to support once-monthly administration of a peptidic GLP-1R agonist. Initially, the prototypical GLP-1R agonist exenatide was covalently attached to hydrogel microspheres by a self-cleaving ß-eliminative linker; after subcutaneous injection in rats, the peptide was slowly released into the systemic circulation. However, the short serum exenatide half-life suggested its degradation in the subcutaneous depot. We found that exenatide undergoes deamidation at Asn28 with an in vitro and in vivo half-life of approximately 2 weeks. The [Gln28]exenatide variant and exenatide showed indistinguishable GLP-1R agonist activities as well as pharmacokinetic and pharmacodynamic effects in rodents; however, unlike exenatide, [Gln28]exenatide is stable for long periods. Two different hydrogel-[Gln28]exenatide conjugates were prepared using ß-eliminative linkers with different cleavage rates. After subcutaneous injection in rodents, the serum half-lives for the released [Gln28]exenatide from the two conjugates were about 2 weeks and one month. Two monthly injections of the latter in the Zucker diabetic fatty rat showed pharmacodynamic effects indistinguishable from two months of continuously infused exenatide. Pharmacokinetic simulations indicate that the delivery system should serve well as a once-monthly GLP-1R agonist for treatment of type 2 diabetes in humans.
Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Sistemas de Liberação de Medicamentos , Receptor do Peptídeo Semelhante ao Glucagon 1/agonistas , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Hipoglicemiantes/administração & dosagem , Microesferas , Humanos , Hidrogel de Polietilenoglicol-Dimetacrilato/administração & dosagem , Hidrogel de Polietilenoglicol-Dimetacrilato/farmacocinética , Hipoglicemiantes/farmacocinética , Estrutura Molecular , Fatores de TempoRESUMO
We developed two types of polyethylene glycol (PEG)-based surgical sealants, which we have termed the PER and PRO series. In one, the PRO series, an 8-arm PEG containing activated carbonyl end-groups was reacted with a 4-armed amino-PEG. In the second, the PER series, a 4-arm PEG containing bi-functional end groups with four azides and four activated esters was reacted by strain-promoted alkyne-azide cycloaddition with a 4-arm cyclooctyne-PEG to give a near-ideal Tetra-PEG hydrogel. The sealants showed predictably tunable strength, swelling, adhesion, and gelation properties. The gels were compared to commercially available PEG-based sealants and exhibit physical properties equivalent to or better than the standards. Variants of each gel-format were prepared that contained a ß-eliminative cleavable linker in the crosslinks to control degradation rate. Linkers of this type self-cleave with half-lives spanning from hours to years, and offer the unique ability to precisely tune the degradation to match the healing process. In addition, these linkers could serve as cleavable tethers for controlled drug release. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1602-1611, 2017.
Assuntos
Plásticos Biodegradáveis/química , Teste de Materiais , Polietilenoglicóis/química , Adesivos Teciduais/química , Humanos , PressãoRESUMO
The utility of antigen-binding antibody fragments is often limited by their short half-lives. Half-life extension of such fragments is usually accomplished by attachment or binding to high-molecular-weight carriers that reduce the renal elimination rate. However, the higher hydrodynamic radius results in greater confinement in the vascular compartment and, thus, lower tissue distribution. We have developed a chemically controlled drug delivery system in which the drug is covalently attached to hydrogel microspheres by a self-cleaving ß-eliminative linker; upon subcutaneous injection, the t1/2,ß of the released drug acquires the t1/2 of linker cleavage. In the present work, we compared the pharmacokinetics of an anti-TNFα scFv, the same scFv attached to 40 kDa PEG by a stable linker, and the scFv attached to hydrogel microspheres by a self-cleaving linker. We also developed a general approach for the selective attachment of ß-eliminative linkers to the N-termini of proteins. In rats, the scFv had a t1/2,ß of 4 h and a high volume of distribution at steady state (Vd,SS), suggesting extensive tissue distribution. The PEG-scFv conjugate had an increased t1/2,ß of about 2 days but showed a reduced Vd,SS that was similar to the plasma volume. In contrast, the tissue-penetrable scFv released from the hydrogel system had a t1/2,ß of about 2 weeks. Thus, the cleavable microsphere-scFv conjugate releases its protein cargo with a prolonged half-life comparable to that of most full-length mAbs and in a form that has the high tissue distribution characteristic of smaller mAb fragments. Other antigen-binding antibody fragments should be amenable to the half-life extension approach described here.
RESUMO
We developed a long-acting drug-delivery system that supports subcutaneous administration of the peptidic somatostatin agonist octreotide-a blockbuster drug used to treat acromegaly and neuroendocrine tumors. The current once-a-month polymer-encapsulated octreotide, Sandostatin LAR, requires a painful intragluteal injection through a large needle by a health-care professional. To overcome such shortcomings, Tetra-PEG hydrogel microspheres were covalently attached to the α-amine of d-Phe(1) or the ε-amine of Lys(5) of octreotide by a self-cleaving ß-eliminative linker; upon subcutaneous injection in the rat using a small-bore needle, octreotide was slowly released. The released drug from the ε-octreotide conjugate showed a remarkably long serum half-life that exceeded two months. The α-octreotide conjugate had a half-life of â¼2 weeks, and showed an excellent correlation of in vitro and in vivo drug release. Pharmacokinetic models indicate these microspheres should support once-weekly to once-monthly self-administered subcutaneous dosing in humans. The hydrogel-octreotide conjugate shows the favorable pharmacokinetics of Sandostatin LAR without its drawbacks.
Assuntos
Portadores de Fármacos/química , Hidrogéis/química , Octreotida/administração & dosagem , Octreotida/química , Animais , Preparações de Ação Retardada , Injeções Subcutâneas , Microesferas , Polietilenoglicóis/química , RatosRESUMO
We have developed a unique long-acting drug-delivery system for the GLP-1 agonist exenatide. The peptide was covalently attached to Tetra-PEG hydrogel microspheres by a cleavable ß-eliminative linker; upon s.c. injection, the exenatide is slowly released at a rate dictated by the linker. A second ß-eliminative linker with a slower cleavage rate was incorporated in polymer cross-links to trigger gel degradation after drug release. The uniform 40 µm microspheres were fabricated using a flow-focusing microfluidic device and in situ polymerization within droplets. The exenatide-laden microspheres were injected subcutaneously into the rat, and serum exenatide measured over a one-month period. Pharmacokinetic analysis showed a t1/2,ß of released exenatide of about 7 days which represents over a 300-fold half-life extension in the rat and exceeds the half-life of any currently approved long-acting GLP-1 agonist. Hydrogel-exenatide conjugates gave an excellent Level A in vitro-in vivo correlation of release rates of the peptide from the gel, and indicated that exenatide release was 3-fold faster in vivo than in vitro. Pharmacokinetic simulations indicate that the hydrogel-exenatide microspheres should support weekly or biweekly subcutaneous dosing in humans. The rare ability to modify in vivo pharmacokinetics by the chemical nature of the linker indicates that an even longer acting exenatide is feasible.