Longer Circulation Half-life Research Articles

Predicting the spontaneous vaporisation of superheated perfluorocarbon droplets

Superheated perfluorocarbon droplets have been widely explored as agents for ultrasound imaging and therapy, as well as for other applications such as radiation dosimetry. Submicrometre, or “nano” droplets offer a number of potential advantages over microbubbles, e.g., longer circulation half-lives, higher surface area-to-volume ratio and the ability to perfuse the microvasculature more easily. A key challenge in the use of nanodroplets, however, is the need to avoid spontaneous vaporisation whilst keeping the energy required for acoustic activation within the range of pressures that can be used safely in humans. This is especially important for imaging applications. Perfluoropropane (C;3F;8) microbubbles can be condensed to form liquid nanodroplets that offer a good trade-off between thermal stability and acoustic vaporisation threshold. Anecdotal reports, however, suggest that C;3F;8 droplets can spontaneously vaporise, and may therefore pose a potential safety risk, especially if bubble coalescence occurs. The aim of this study was to build on recent theoretical models of droplet vaporisation and investigate the probability of vaporisation as a function of temperature and interfacial tension. The results are compared with experimental measurements of vaporisation rates for different droplet formulations.

Macrophages as Promising Carriers for Nanoparticle Delivery in Anticancer Therapy.

Macrophages play a critical role in the immune response due to their ability to recognize and remove pathogens, as well as present antigens, which are involved in inflammation, but they are also one of the most abundant immune cell populations present in the tumor microenvironment. In recent years, macrophages have become promising cellular carriers for drug and nanoparticle delivery to the tumor microenvironment, mainly due to their natural properties such as biocompatibility, degradability, lack of immunogenicity, long half-life in circulation, crossing biological barriers, and the possibility of migration and accumulation at a site of inflammation such as a tumor. For the effectiveness of this therapeutic strategy, known as "Trojan horse", it is important that the nanoparticles engulfed by macrophages do not affect their proper functioning. In our review, we discussed how the size, shape, chemical and mechanical properties of nanoparticles influence their internalization by macrophages. In addition, we described the promising research utilizing macrophages, their cell membranes and macrophage-derived exosomes as drug carriers in anticancer therapy. As a prospect of the wider use of this therapeutic strategy, we postulate its future application in boron delivery to the tumor environment in boron neutron capture therapy.

Phase 1 trial of a novel C’Dot drug conjugate (CDC), ELU001, in patients with solid tumors known to overexpress folate receptor alpha (FRα).

TPS3159 Background: ELU001 is a novel first-in-class nanoparticle drug conjugate that consists of ~13 folic acid targeting moieties and a payload of ~22 molecules of the topoisomerase-1 inhibitor, exatecan. Folic acid and exatecan are covalently bound by non-cleavable and cathepsin-B cleavable linkers, respectively, to short polyethylene glycol chains which surround the C’Dot’s silica core. CDCs are very small (~6 nm), allowing for more efficient penetration into solid tumors compared to ADCs and a rapid elimination by the kidneys, which is expected to lead to less toxicity than ADCs that have a longer half-life in circulation. ELU001’s high avidity is designed to promote binding to FRα on the surface of cancer cells that express any level of antigen (low to high). ELU001 then internalizes into the tumor cell and traffics to the lysosome where enzymatic cleavage releases the exatecan payload. ELU001 has demonstrated efficacy in preclinical models with low, moderate and high levels of FRα. The first-in-human trial, ELU-FRα-1, is currently recruiting patients with ovarian, endometrial, colorectal, gastric, gastroesophageal junction, triple negative breast, or non-small cell lung cancers, or cholangiocarcinoma cancers, and, in the opinion of the Investigator, have no meaningful life-prolonging therapy option available. Methods: This is a Phase 1 / 2 multicenter, open label clinical trial with two parts: Part 1 Dose Escalation and Part 2 Tumor Group Expansion Cohort(s). In Part 1, patients with cancer types with a high likelihood of having FRα overexpressing tumors, (ovarian, endometrial, colorectal, gastric, gastroesophageal junction, triple negative breast, or non-small cell lung cancers, or cholangiocarcinoma) will be enrolled. FRα expression is determined retrospectively. ELU001 is administered either weekly (QW) (once a week for 3 weeks, 1 week rest), every other week (Q2W, with no rest between cycles), or every three weeks (Q3W). Initial Part 2 expansion cohorts are planned in ovarian cancer with high FRα expression, ovarian cancer with moderate or low FRα expression, and endometrial cancer with any positive FRα expression. Here, FRα will be prospectively determined. Other cancer types may be assessed in the future. The primary objective for Part 1 is to identify the MTD/RP2D. The primary objective for Part 2 is to determine the ORR. Secondary objectives include DOR, PFS, TFST, PFS2, OS, frequency, severity and tolerability of adverse events, PK, ADA, and FRα expression assessments. Part 1 Dose Escalation will recruit about 2-5 patients at each dose for each regimen (QW; Q2W; Q3W). Part 2 Stage 1 will recruit about 15 patients per tumor group expansion cohort and is expected to begin recruitment in the second half of 2023. The study is enrolling in Part 1 Q2W Cohort 301 and Q3W Cohort A in the US. Clinical trial information: NCT05001282 .

Abstract CT255: ELU-FRα-1: a study to evaluate ELU001 in patients with solid tumors that overexpress folate receptor alpha (FRα)

Abstract Background: ELU001 is a novel, first-in-class, new molecular entity described as a C’Dot Drug Conjugate (CDC). ELU001 consists of ~13 folic acid targeting moieties and a payload of ~22 molecules of the topoisomerase-1 inhibitor, exatecan. Folic acid and exatecan are covalently bound by non-cleavable and cathepsin-B cleavable linkers, respectively, to short polyethylene glycol chains which surround the C’Dot’s silica core. CDCs are very small (~6 nm), allowing greater ability to penetrate more efficiently into solid tumors compared to ADCs. CDCs are rapidly eliminated by the kidneys, which is expected to lead to less toxicity than ADCs that have a longer half-life in circulation. ELU001’s high avidity is designed to promote binding to FRα on the surface on FRα overexpressing cancer cells with a wide range of antigen expression including high, moderate and low expressing tumor cells. Following antigen binding, ELU001 internalizes into the tumor cell, and traffics to the lysosome where enzymatic cleavage releases the exatecan payload. The first-in-human trial, ELU-FRα-1, is currently recruiting patients that have advanced, recurrent or refractory tumors associated with indications that are known to potentially overexpress FRα and have been shown to be topoisomerase 1 inhibitor-sensitive, and, in the opinion of the Investigator, have no satisfactory therapeutic options available. Methods: This is a Phase 1/2 multicenter, open label clinical trial with two parts: Part 1 Dose Escalation and Part 2 Tumor Group Expansion Cohort(s). Part 1 is a basket trial enrolling patients with cancer types with a high likelihood of having FRα overexpressing tumors, (specifically, ovarian, endometrial, colorectal, gastric, gastroesophageal junction, triple negative breast, or non-small cell lung cancers, or cholangiocarcinoma). Patients are receiving ELU001 weekly (QW) (once a week for 3 weeks, 1 week rest), every other week (Q2W, with no rest between cycles), or every three weeks (Q3W). Analysis of FRα expression will be retrospectively determined. Part 2 will use Simon’s Two-Stage design to evaluate 4-6 Expansion Cohorts, comprised of tumor histologies anticipated to have greatest activity to ELU001 treatment. FRα will be prospectively determined. The primary objective for Part 1 is to identify the MTD/RP2D. The primary objective for Part 2 is to determine the ORR. Secondary objectives include DOR, PFS, TFST, PFS2, OS, frequency, severity and tolerability of adverse events, PK, ADA, and FRα expression assessments. Part 1 Dose Escalation will recruit about 25 patients per dose regimen (QW; Q2W; Q3W). The first stage of Part 2 (Dose Expansion) will recruit about 15 patients per tumor group expansion cohort. The study is actively enrolling in the US and currently recruiting in Q2W Cohort 201 and Q3W Cohort A. QW Cohorts 1-3 and Q2W Cohort 101 are complete. Clinical trial information: NCT05001282. Citation Format: Wen Wee Ma, Anthony Tolcher, Cesar A. Perez, Douglass Orr, Erika Hamilton, Yujie Zhao, Yonina Murciano-Goroff, Carey Anders, Gregory P. Adams, Catherine W. Reddick, Eliel Bayever. ELU-FRα-1: a study to evaluate ELU001 in patients with solid tumors that overexpress folate receptor alpha (FRα) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT255.

Effective loading of incompatible drugs into nanosized vesicles: a strategy to allow concurrent administration of furosemide and midazolam in simulated clinical settings

The current study aims to assess the use of nanocarriers to limit drug incompatibilities in clinical settings, and thus eliminating serious clinical consequences (e.g., catheter obstruction and embolism), and enhancing in vivo bioavailability and efficacy. As a proof-of-concept, the impact of loading well-documented physically incompatible drugs (i.e., furosemide and midazolam) into nanosized vesicles on in vitro stability and in vivo bioavailability of the two drugs was investigated. Furosemide and midazolam were loaded into nanosized spherical vesicles at high entrapment efficiency (ca. 62–69%). The drug-loaded vesicles demonstrated a sustained drug release patterns, high physical stability and negligible hemolytic activity. Physical incompatibility was assessed by exploiting microscopic technique coupled with image processing and analysis, dynamic light scattering and laser Doppler anemometry. Incorporation of drugs separately inside the nanosized vesicles dramatically decreased size and number of the precipitated particles. In vivo, the niosomal drug mixture demonstrated a significant improvement in pharmacokinetic profiles of furosemide and midazolam compared to the mixed free drug solutions, as evidenced by their longer circulation half-lives and higher area under the plasma-concentration time curves of both drugs. Nanocarriers could provide an auspicious strategy for circumventing drug incompatibilities, thus reducing adverse reactions, hospitalization period and improving therapeutic outcomes.

ELU-FRα-1: A study to evaluate ELU001 in patients with solid tumors that overexpress folate receptor alpha (FRα).

TPS3158 Background: ELU001 is a novel, first-in-class, new molecular entity described as a C’Dot Drug Conjugate (CDC). ELU001 consists of ̃12 folic acid targeting moieties and ̃22 exatecan topoisomerase-1 inhibitor payloads on Cathepsin-B cleavable linkers covalently bound to the surface of each silicon core/polyethylene glycol C’Dot nanoparticle. CDCs are small in size (̃6 nm), have a greater ability to penetrate into and through tumors as compared to ADCs, and are rapidly eliminated by the kidneys. The rapid systemic elimination is expected to lead to less toxicity than is observed with targeting platforms like ADCs that have a longer half-life in circulation. ELU001’s high avidity is believed to promote internalization into FRα overexpressing cancer cells, selectively delivering it’s ̃22 molecules of payload. The first-in-human clinical trial, ELU-FRα-1, is currently recruiting patients that have advanced, recurrent or refractory FRα overexpressing tumors considered to be topoisomerase 1 inhibitor-sensitive based on the literature, and, in the opinion of the Investigator, have no satisfactory therapeutic options available. Methods: This is a Phase 1 / 2 multicenter, open label clinical trial with two parts: Part 1 Dose Escalation and Part 2 Tumor Group Expansion Cohort(s). In Part 1, patients with cancer types with a high likelihood of having FRα overexpressing tumors based on historical data, (specifically, ovarian, endometrial, colorectal, gastric, gastroesophageal junction, triple negative breast, or non-small cell lung cancers, or cholangiocarcinoma), will be enrolled to the study. Patients will receive ELU001 on a weekly dose regimen (QW) (once a week for 3 weeks, 1 week rest) or every other week dose regimen (Q2W, with no rest between cycles). Retrospective analysis of FRα expression will be determined. Part 2 uses a Simon’s Two-Stage design to evaluate 4-6 tumor group expansion cohorts, each consisting of patients with specific tumor types (to be identified based on emerging data) that overexpress FRα (prospectively determined prior to enrollment). The primary objective for Part 1 is to identify the MTD/RP2D and for Part 2 is ORR. Dose Escalation will recruit about 25 patients per dose regimen (QW or Q2W). Dose Expansion will recruit about 15 patients per tumor group expansion cohort. Secondary objectives are anti-tumor activity (DOR, PFS, TFST, PFS2, OS), frequency, severity and tolerability of adverse events, PK, ADA, and FRα expression assessments. The study is actively enrolling in the US – Cohorts 1-2 have been completed without DLT. Enrollment to Cohort 3 began in December 2021. Clinical trial information: NCT05001282 .

Pharmacokinetics and Pharmacodynamics of Recombinant FIX Variants in the FIX Knockout Mouse Tail Clip Bleeding Model

Introduction: The recessive X-linked bleeding disorder Hemophilia B is caused by a mutation in the coagulation factor (F) IX gene leading to partial or total loss of its function. Preventive treatment with replacement long-acting FIX is an attractive option for patients to reduce administration frequency and prevent bleeding. New recombinant FIX therapeutics like the albumin-fused FIX (rFIX-FP) or the Fc-fused FIX (rFIX-Fc) enable longer half-life in circulation and thus less frequent administration, as compared to non-fused FIX (rFIX). Studies in FIX knockout (KO) mice were conducted to characterize the effect of the modifications on the pharmacokinetic (PK) and pharmacodynamic (PD) properties of the different recombinant FIX products.Methods: Pharmacokinetics: Recombinant FIXs were administered intravenously at doses of 25 nmol/kg (corresponding to ~175-400 IU/kg FIX clotting activity) to FIX KO mice. Blood samples were collected starting at 5 min, and up to 336 h. FIX plasma levels were measured with an ELISA-based assay with anti-human FIX paired antibodies. PK was evaluated by non-compartmental analysis. Biodistribution: 3H-labeled recombinant FIXs were administered intravenously at doses of 200 IU/kg to FIX KO mice. Plasma levels and organ distribution were quantified starting at 15 min, and up to 240 h. Pharmacodynamics: FIX KO mice were treated intravenously with 50 IU/kg FIX clotting activity (nominal or labeled potency) of different rFIX products at 24, 72, 120 168 and 336 h prior to determination of bleeding time and total blood loss in a tail clip bleeding model. Immediately upon lesion, the tail tip was submerged in isotonic saline (0.9 %), kept at the mice physiological body temperature. Time to hemostasis is quantified as the time until bleeding stops for a minimum of 2 min. The volume of total blood loss was calculated by measuring the hemoglobin present in the isotonic saline solution at the end of the experiment.Results: Distinct PK profiles were observed for the three FIX molecules, where rFIX and rFIX-Fc exhibit an initial rapid distribution phase from plasma, while rFIX-FP showed a monophasic elimination profile up to 120 h post administration (p.a.). In the terminal phase, rFIX levels were quantifiable for up to 48 h p.a., while both; rFIX-FP and rFIX-Fc were measurable in plasma up to 240 h p.a. In line with this, the overall exposure AUC 0-inf is ranked in the following order: rFIX-FP > rFIX-Fc > rFIX.In the biodistribution study, a similar plasma PK profile was determined. Given the sensitivity of the radioactive method, an exposure plateau was observed for rFIX-Fc, and at lower levels for rFIX, whereas rFIX-FP continued to exhibit monophasic plasma clearance behavior. rFIX-FP exposure in the extravascular space (EVS) was lower than for the other FIX products. This is in line with volumes of distribution (Vss and Vz) which were highest for rFIX-Fc (AUC ranking rFIX-Fc > rFIX > rFIX-FP).FIX hemostatic efficacy in tail clip model was comparable for all 3 FIXs at the early time points but diverged at later time points post dosing. The blood loss and bleeding time measurements returned to baseline within 168 h for rFIX and rFIX-Fc, while the rFIX-FP group maintained robust hemostatic activity for up to 336 h. In contrast to lowest tissue exposure of rFIX-FP, the plasma AUC for rFIX-FP was highest, compared to FIX-Fc or FIX. In line, efficacy over time was also highest for rFIX-FP, suggesting that tissue exposure might not be the main driver for hemostatic activity.Conclusion: Different FIX products exhibit divergent PK and PD behaviors. rFIX-FP plasma PK profile suggests somewhat lower tissue distribution in comparison to rFIX-Fc and rFIX, which was confirmed in the tissue biodistribution study. Despite its limited extravasation into tissue, rFIX-FP exhibits superior and prolonged hemostatic activity in the FIX KO mouse tail clip model. rFIX and rFIX-Fc show comparable tissue biodistribution behavior, with robust extravasation into the EVS. Despite having the longest half-life and overall (plasma and tissue) exposure in the mouse, rFIX-Fc lost hemostatic activity in the tail clip model significantly faster than rFIX-FP. As a result, hemostatic efficacy was highest for the FIX-FP, the product with the lowest distribution volumes. The results therefore suggest that EVS is not the main determining factor for FIX efficacy in vivo. DisclosuresPestel: CSL Behring Innovation GmbH: Current Employment, Current equity holder in publicly-traded company. Peil: CSL Behring Innovation GmbH: Current Employment, Current equity holder in publicly-traded company. Knoll Machado: CSL Behring Innovation GmbH: Current Employment, Current equity holder in publicly-traded company. Claar: CSL Behring Innovation GmbH: Current Employment, Current equity holder in publicly-traded company. Raquet: CSL Behring Innovation GmbH: Current Employment, Current equity holder in publicly-traded company. Ponnuswamy: CSL Behring Innovation GmbH: Current Employment, Current equity holder in publicly-traded company. Mischnik: CSL Behring Innovation GmbH: Current Employment, Current equity holder in publicly-traded company. Herzog: CSL Behring GmbH: Current Employment, Current equity holder in publicly-traded company.

A First-In-Class, Humanized Antibody Targeting Alternatively Spliced Tissue Factor: Preclinical Evaluation in an Orthotopic Model of Pancreatic Ductal Adenocarcinoma

In 2021, pancreatic ductal adenocarcinoma (PDAC) is the 3rd leading cause of cancer deaths in the United States. This is largely due to a lack of symptoms and limited treatment options, which extend survival by only a few weeks. There is thus an urgent need to develop new therapies effective against PDAC. Previously, we have shown that the growth of PDAC cells is suppressed when they are co-implanted with RabMab1, a rabbit monoclonal antibody specific for human alternatively spliced tissue factor (asTF). Here, we report on humanization of RabMab1, evaluation of its binding characteristics, and assessment of its in vivo properties. hRabMab1 binds asTF with a KD in the picomolar range; suppresses the migration of high-grade Pt45.P1 cells in Boyden chamber assays; has a long half-life in circulation (~ 5 weeks); and significantly slows the growth of pre-formed orthotopic Pt45.P1 tumors in athymic nude mice when administered intravenously. Immunohistochemical analysis of tumor tissue demonstrates the suppression of i) PDAC cell proliferation, ii) macrophage infiltration, and iii) neovascularization, whereas RNAseq analysis of tumor tissue reveals the suppression of pathways that promote cell division and focal adhesion. This is the first proof-of-concept study whereby a novel biologic targeting asTF has been investigated as a systemically administered single agent, with encouraging results. Given that hRabMab1 has a favorable PK profile and is able to suppress the growth of human PDAC cells in vivo, it comprises a promising candidate for further clinical development.

Long circulating tracer tailored for magnetic particle imaging.

Superparamagnetic iron oxide nanoparticle (SPION) tracers possessing long blood circulation time and tailored for magnetic particle imaging (MPI) performance are crucial for the development of this emerging molecular imaging modality. Here, single-core SPION MPI tracers coated with covalently bonded polyethyelene glycol (PEG) brushes were obtained using a semi-batch thermal decomposition synthesis with controlled addition of molecular oxygen, followed by an optimized PEG-silane ligand exchange procedure. The physical and magnetic properties, MPI performance, and blood circulation time of these newly synthesized tracers were compared to those of two commercially available SPIONs that were not tailored for MPI but are used for MPI: ferucarbotran and PEG-coated Synomag®-D. The new tailored tracer has MPI sensitivity that is ~3-times better than the commercial tracer ferucarbotran and much longer circulation half-life than both commercial tracers (t1/2=6.99 h for the new tracer, vs t1/2=0.59 h for ferucarbotran, and t1/2=0.62 h for PEG-coated Synomag®-D).

<p>Combination of drugs and carriers in drug delivery technology and its development</p>

The development of drug-loading technology will bring new and rapid development to the treatment of diseases. At present, drug delivery by nanoparticles, erythrocyte, and platelet have been studied extensively. Compared with traditional anticancer drugs, nano-drugs have shown many obvious advantages, disease treatment based on nanotechnology will bring a revolution in cancer treatment. Due to its inherent biocompatibility, large drug load and long half-life in the blood circulation, erythrocyte-inspired antibiotics, and some anticancer drugs delivery systems have also entered the clinical trial stage. At present, there are relatively few studies on drug delivery by platelets as carriers. It is necessary to overcome the shortcomings of platelets, such as easy activation, deformation, thrombosis, and difficult preservation. There are many ways to combine drugs with these carriers, and each has its own advantages and disadvantages. It is necessary to seek the best combination scheme to increase drug loading and reduce the damage to therapeutic components to the carriers, so as to bring more mature and reliable methods for the clinical application of drug delivery technology. Several drug-loading technologies and their development were described according to various categories. The combination of drugs and carriers is summarized for better understanding of its practical application.

Versatile and Finely Tuned Albumin Nanoplatform based on Click Chemistry.

Albumin is one of the most attractive nanoplatforms for targeted imaging and drug delivery due to its biocompatibility and long circulation half-life. However, previously reported albumin-based nanoplatforms have shown inconsistent blood circulation half-life according to the modified methods, and the affecting factors were not well evaluated, which could hamper the clinical translation of albumin-based nanoplatforms. Herein, we developed a finely tuned click-chemistry based albumin nanoplatform (CAN) with a longer circulation half-life and an efficient tumor targeting ability.Methods: CAN was synthesized in two steps. First, albumin was conjugated with ADIBO-NHS (albumin-ADIBO) by reacting albumin with various molar ratios of ADIBO. The number of attached ADIBO moieties was determined using matrix-assisted laser desorption ionization time of flight (MALDI-TOF). Second, the desired modalities including azide-functionalized chelator, a fluorescence dye, and folate were incorporated into albumin-ADIBO using strain-promoted alkyne-azide cycloaddition reaction (SPAAC reaction). The biodistribution and targeting efficiency of functionalized CANs were demonstrated in mice.Results: The degree of functionalization (DOF) and resulting in vivo biodistribution was controlled precisely using the click chemistry approach. Specifically, the numbers of attached azadibenzocyclooctyne (ADIBO) moieties on albumin, the DOF, were optimized by reacting albumin with varying molar ratios of ADIBO with a high reproducibility. Furthermore, we developed a simple and efficient method to estimate the DOF using UV-visible spectrophotometry (UV-vis), which was further validated by matrix-assisted laser desorption ionization time of flight (MALDI-TOF). The biodistribution of CAN could be controlled by DOF, and CAN with an optimized DOF showed a long circulation half-life (> 18 h). CAN was further functionalized using a simple click chemistry reaction with an azide functionalized chelator, a fluorescence dye, and folate. 64Cu- and folate-labeled CAN (64Cu-CAN-FA) showed effective and specific folate receptor targeting in vivo, with an over two-fold higher uptake than the liver at 24 h post-injection.Conclusions: Our development from the precisely controlled DOF demonstrates that an optimized CAN can be used as a multifunctional nanoplatform to obtain a longer half-life with radioisotopes and ligands, and provides an effective method for the development of albumin-based tumor theranostic agents.

3-O sulfation of heparin leads to hepatotropism and longer circulatory half-life

IntroductionHeparins are common blood anticoagulants that are critical for many surgical and biomedical procedures used in modern medicine. In contrast to natural heparin derived from porcine gut mucosa, synthetic heparins are homogenous by mass, polymer length, and chemistry. Materials & methodsStable cell lines expressing the human and mouse Stabilin receptors were used to evaluate endocytosis of natural and synthetic heparin. We chemoenzymatically produced synthetic heparin consisting of 12 sugars (dodecamers) containing 14 sulfate groups resulting in a non-3-O sulfated structure (n12mer). Half of the n12mer was modified with a 3-O sulfate on a single GlcNS sugar producing the 3-O sulfated heparin (12mer). Wildtype (WT), Stabilin-1 knock-out (KO), and Stabilin-2 KO C57BL/6 mice were developed and used for metabolic studies and provided as a source for primary liver sinusoidal endothelial cells. Results & conclusionsHuman and mouse Stabilin-2 receptors had very similar endocytosis rates of both the 12mer and n12mer, suggesting that they are functionally similar in primary cells. Subcutaneous injections of the n12mer and 12mer revealed that the 12mer had a much longer half-life in circulation and a higher accumulation in liver. The n12mer never accumulated in circulation and was readily excreted by the kidneys before liver accumulation could occur. Liver sinusoidal endothelial cells from the Stabilin-2 KO mice had lower uptake rates for both dodecamers, whereas, the Stabilin-1 KO mice had lower endocytosis rates for the 12mer than the n12mer. 3-O sulfation of heparin is correlated to both a longer circulatory half-life and hepatotropism which is largely performed by the Stabilin receptors.

Smart Drug Delivery Systems in Cancer Therapy.

Smart nanocarriers have been designed for tissue-specific targeted drug delivery, sustained or triggered drug release and co-delivery of synergistic drug combinations to develop safer and more efficient therapeutics. Advances in drug delivery systems provide reduced side effects, longer circulation half-life and improved pharmacokinetics. Smart drug delivery systems have been achieved successfully in the case of cancer. These nanocarriers can serve as an intelligent system by considering the differences of tumor microenvironment from healthy tissue, such as low pH, low oxygen level, or high enzymatic activity of matrix metalloproteinases. The performance of anti-cancer agents used in cancer diagnosis and therapy is improved by enhanced cellular internalization of smart nanocarriers and controlled drug release. Here, we review targeting, cellular internalization; controlled drug release and toxicity of smart drug delivery systems. We are also emphasizing the stimulus responsive controlled drug release from smart nanocarriers.

Anticancer protein that bites polymer tail is more effective

Cyclizing the termini of protein drugs can improve their pharmaceutical properties modestly, and adding polymers to protein drugs can improve their ability to last a long time in the bloodstream. But anticancer protein-polymer conjugates are often too bulky to enter tumors deeply. Researchers now find that cyclization and polymer conjugation work better together than alone. Hua Lu of Peking University and coworkers cyclized a conjugate of the anticancer protein interferon and an amino acid polymer. Compared with noncyclized conjugates, the cyclized agents have longer circulation half-life, remarkably higher retention time in tumors, and deeper tumor penetration in mice (J. Am. Chem. Soc. 2017, DOI: 10.1021/jacs.7b13017). It also inhibits tumor progression and extends survival in mice bearing grafted human tumors, while minimizing liver-damaging side effects. The researchers have not confirmed those findings in people yet, but they believe that their study provides the best evidence so far that cyclizing protein-polymer conjugates

Enzymes as Immunotherapeutics.

Enzymes are attractive as immunotherapeutics because they can catalyze shifts in the local availability of immunostimulatory and immunosuppressive signals. Clinical success of enzyme immunotherapeutics frequently hinges upon achieving sustained biocatalysis over relevant time scales. The time scale and location of biocatalysis are often dictated by the location of the substrate. For example, therapeutic enzymes that convert substrates distributed systemically are typically designed to have a long half-life in circulation, whereas enzymes that convert substrates localized to a specific tissue or cell population can be more effective when designed to accumulate at the target site. This Topical Review surveys approaches to improve enzyme immunotherapeutic efficacy via chemical modification, encapsulation, and immobilization that increases enzyme accumulation at target sites or extends enzyme half-life in circulation. Examples provided illustrate "replacement therapies" to restore deficient enzyme function, as well as "enhancement therapies" that augment native enzyme function via supraphysiologic doses. Existing FDA-approved enzyme immunotherapies are highlighted, followed by discussion of emerging experimental strategies such as those designed to enhance antitumor immunity or resolve inflammation.

Liposomes as colloidal nanovehicles: on the road to success in intravenous drug delivery

Abstract The advancement of research in colloidal systems has led to the increased application of this technology in more effective and targeted drug delivery. Nanotechnology enables control over functionality parameters and allows innovations in biodegradable, biocompatible, and stimuli-responsive delivery systems. The first closed bilayer phospholipid system, the liposome system, has been making steady progress over five decades of extensive research and has been efficient in achieving many desirable parameters such as remote drug loading, size-controlling measures, longer circulation half-lives, and triggered release. Liposome-mediated drug delivery has been successful in overcoming obstacles to cellular and tissue uptake of drugs with improved biodistribution in vitro and in vivo. These colloidal nanovehicles have moved on from a mere concept to clinical applications in various drug delivery systems for antifungal, antibiotic, and anticancer drugs.

Macrophage colony-stimulating factor (CSF1) controls monocyte production and maturation and the steady-state size of the liver in pigs.

Macrophage colony-stimulating factor (CSF1) is an essential growth and differentiation factor for cells of the macrophage lineage. To explore the role of CSF1 in steady-state control of monocyte production and differentiation and tissue repair, we previously developed a bioactive protein with a longer half-life in circulation by fusing pig CSF1 with the Fc region of pig IgG1a. CSF1-Fc administration to pigs expanded progenitor pools in the marrow and selectively increased monocyte numbers and their expression of the maturation marker CD163. There was a rapid increase in the size of the liver, and extensive proliferation of hepatocytes associated with increased macrophage infiltration. Despite the large influx of macrophages, there was no evidence of liver injury and no increase in circulating liver enzymes. Microarray expression profiling of livers identified increased expression of macrophage markers, i.e., cytokines such as TNF, IL1, and IL6 known to influence hepatocyte proliferation, alongside cell cycle genes. The analysis also revealed selective enrichment of genes associated with portal, as opposed to centrilobular regions, as seen in hepatic regeneration. Combined with earlier data from the mouse, this study supports the existence of a CSF1-dependent feedback loop, linking macrophages of the liver with bone marrow and blood monocytes, to mediate homeostatic control of the size of the liver. The results also provide evidence of safety and efficacy for possible clinical applications of CSF1-Fc.

Trimeric PEG-Conjugated Exendin-4 for the Treatment of Sepsis.

Exendin-4 (EX4), a glucagon-like peptide-1 receptor (GLP-1R) agonist that regulates blood glucose levels, has been used in the management of type-2 diabetes mellitus. EX4 can be PEGylated to improve its antidiabetic effects by enhancing its stability and extending the circulation half-life. Here, to determine whether PEGylated EX4 is effective for the treatment of sepsis, C-terminal thiol-specific PEGylated EX4s with linear maleimide-PEG-2K, -5K, -20K and trimeric maleimide-PEG-50K (hereafter referred to as EX4-2K, EX4-5K, EX4-20K, and EX4-50K, respectively) were prepared, and their antiseptic responses were investigated. These PEGylated EX4s reduced cecal ligation and puncture (CLP)-induced organ injury by decreasing hyperpermeability, and suppressing interactions between leukocytes and endothelial cells. The binding avidity and stability of EX4-50K toward GLP-1R were superior to that of wild-type EX4, as was the circulation half-life of EX4-50K. In addition, the antiseptic effects of EX4-50K were superior to those of other PEGylated EX4s, which may be attributed to enhanced proteolytic stability, longer circulation half-life, and higher receptor-binding affinity of EX4-50K due to its trimeric PEG structure. Therefore, EX4-50K may decrease CLP-induced septic mortality in vivo. There are currently neither effective preventatives against nor treatment options for sepsis; our results show that EX4-50K has the potential to treat sepsis.

Variation of Pharmacokinetic Profiles of Some Antidiabetic Drugs from Nanostructured Formulations Administered Through Pulmonary Route.

Diabetes is a chronic disease that occurs when the pancreas does not produce enough insulin, or when the body cannot effectively use the insulin it produces. WHO projects that diabetes death will be doubled between 2005 and 2030, where 347 million people worldwide had diabetes as per the report of 2013. The increase in the prevalence of diabetes is due to three influences - lifestyle, ethnicity, and age. The present review summarizes the pharmacokinetic parameters and challenges in the field of nanoparticles and nanoliposomes of insulin and other antidiabetic drugs given through pulmonary route to treat diabetes effectively. Current challenges in diabetes management include optimizing the use of the already available therapies to ensure adequate glycemic condition, blood pressure, lipid control and to reduce complications. At present, several pieces of research have been focusing on new management options for diabetes. Among these options, the use of nanomedicine is becoming an eye catching and most promising one. Currently, nanoparticles and nanoliposomes are thrust areas of research to treat any deadly disease like diabetes. These drug delivery systems ultimately result in longer circulation half-lives, improved drug pharmacokinetics, and reduced side effects of therapeutically active substances that may be insulin and non-insulin. Thus, the pulmonary route is the most promising alternative route of drug delivery since it is non-invasive and lungs have a large surface area, richly supplied by the capillary network, for absorption of drugs.

Efficient and Tumor Targeted siRNA Delivery by Polyethylenimine-graft-polycaprolactone-block-poly(ethylene glycol)-folate (PEI-PCL-PEG-Fol).

Efficient delivery of functional nucleic acids into specific cells or tissues is still a challenge for gene therapy and largely depends on targeted delivery strategies. The folate receptor (FR) is known to be overexpressed extracellularly on a variety of human cancers and is therefore an outstanding gate for tumor-targeted Trojan horse-like delivery of therapeutics. In this study, an amphiphilic and biodegradable ternary copolymer conjugated with folate as ligand, polyethylenimine-graft-polycaprolactone-block-poly(ethylene glycol)-folate (PEI-PCL-PEG-Fol) was synthesized and evaluated for targeted siRNA delivery via folate-FR recognition. The amphiphilic character of similar polymers was shown previously to support endosomal release of endocytosed nanocarriers and to promote formation of long circulating micelles. The obtained PEI-PCL-PEG-Fol exhibited less cytotoxicity in comparison with the corresponding ternary copolymer without folate (PEI-PCL-PEG) and with unmodified PEI25kDa. Stable micelle-like polyplexes with hydrodynamic diameters about 100 nm were found to have a zeta potential of +8.6 mV, which was lower than that of micelleplexes without folate-conjugation (+13-16 mV). Nonetheless, increased cellular uptake and in vitro gene knockdown of PEI-PCL-PEG-Fol/siRNA micelleplexes were observed in SKOV-3 cells, an FR overexpressing cell line, in comparison with the nonfolate-conjugated ones. Moreover, PEI-PCL-PEG-Fol/siRNA micelleplexes exhibited excellent stability in vivo during the analysis of 120 min and a longer circulation half life than hyPEI25kDa/siRNA polyplexes. Most interestingly, the targeted delivery system yielded 17% deposition of the i.v. injected siRNA per gram in the tumor after 24 h due to the effective folate targeting and the prolonged circulation.