Drug Exposure of Long-Acting Cabotegravir and Rilpivirine in Older People With Human Immunodeficiency Virus: A Pharmacokinetic Modeling Study

Background

The life expectancy of people with human immunodeficiency virus (PWH) has significantly increased, thanks to combined antiretrovirals with improved potency and tolerability. One further step has been achieved with the development of long-acting (LA) injectable antiretrovirals, which allow for infrequent dosing. However, the pharmacokinetics of LA antiretrovirals has been poorly characterized in older PWH, as they are generally excluded from trials. We performed virtual studies using physiologically based pharmacokinetic (PBPK) modeling to determine the anticipated exposure of LA cabotegravir/rilpivirine in older individuals.

Methods

Our PBPK model was verified against available observed data for LA cabotegravir and rilpivirine. Cohorts of virtual individuals aged 20-50, 50-65, or 65-85 years were generated to simulate the exposure of LA cabotegravir/rilpivirine for each age group. The fold changes in trough concentration (Cmin) and in drug exposure (area under the time-concentration curve [AUC]) were determined for older relative to young individuals.

Results

The verified PBPK models predicted an increase in exposure within the 0.8-1.25 fold range for monthly LA cabotegravir/rilpivirine. The Cmin and AUC were predicted to be 29% and 26% higher in older compared with young adults for LA cabotegravir administered bimonthly (every 2 months) and 46% and 41% higher for LA rilpivirine bimonthly. The Cmin and AUC of LA cabotegravir and rilpivirine were predicted to be modestly increased in female compared with male individuals for all age groups.

Conclusions

LA cabotegravir/rilpivirine exposure and trough concentrations are predicted to be higher in older than in young PWH; thus, older adults could have a lower risk to present suboptimal concentrations during the dosing interval.

Development of a physiologically-based pharmacokinetic model to simulate the pharmacokinetics of intramuscular antiretroviral drugs

There is growing interest in the use of long-acting (LA) injectable drugs to improve treatment adherence. However, their long elimination half-life complicates the conduct of clinical trials. Physiologically-based pharmacokinetic (PBPK) modeling is a mathematical tool that allows to simulate unknown clinical scenarios for LA formulations. Thus, this work aimed to develop and verify a mechanistic intramuscular PBPK model. The framework describing the release of a LA drug from the depot was developed by including both the physiology of the injection site and the physicochemical properties of the drug. The framework was coded in Matlab® 2020a and implemented in our existing PBPK model for the verification step using clinical data for LA cabotegravir, rilpivirine, and paliperidone. The model was considered verified when the simulations were within twofold of observed data. Furthermore, a local sensitivity analysis was conducted to assess the impact of various factors relevant for the drug release from the depot on pharmacokinetics. The PBPK model was successfully verified since all predictions were within twofold of observed clinical data. Peak concentration, area under the concentration-time curve, and trough concentration were sensitive to media viscosity, drug solubility, drug density, and diffusion layer thickness. Additionally, inflammation was shown to impact the drug release from the depot. The developed framework correctly described the release and the drug disposition of LA formulations upon intramuscular administration. It can be implemented in PBPK models to address pharmacological questions related to the use of LA formulations.

Environmental impact of Holstein Friesian and 3-breed crossbred dairy cows using a Life Cycle Assessment approach applied to individual animals

This study aimed to set up a Life Cycle Assessment (LCA) approach at level of individual animals to assess the effects of a 3-breed crossbreeding program on the environmental impact of cows. It involved 564 cows, 279 purebred Holstein (HO) and 285 crossbreds (CR), originated from a 3-breed crossbreeding program based on the rotational use of Viking Red, Montebèliarde and HO sires and kept in 2 dairy herds of northern Italy (224 and 340 cows/herd, respectively). The reference unit of the LCA model was the lifetime of cows, from the birth to culling or death. Data were collected at different levels: individual animal-based data referred to the whole life (birth, calving, dry, cull or death dates, and milk production); individual test-date collection of body measures and BCS, used to predict body weight and to estimate energy requirements; common farm-based data concerning herd management (diets composition, and materials used). Data were used to compute: dry matter intake, milk and milk components production, gross income (GI) and income over feed costs (IOFC) pertaining to the lifespan of cows. An individual LCA-derived approach was set up to compute global warming potential (GWP), acidification and eutrophication potential (AP and EP, respectively), and land occupation (LO), which have been associated with different functional units (cow in her whole life or per d of life; kg of milk fat plus protein, and € of GI and of IOFC produced in the herd life). Data were analyzed using a generalized linear model including the fixed effects of genetic group (CR vs HO), farm and their interaction (genetic group x farm). Compared with HO, CR cows completed more lactations (+12%), had earlier first calving (-2 weeks), yielded more fat plus protein in milk both in the lifespan (+8%) and per d of life (+4%). Concerning the environmental impact, when compared with HO herd mates, CR cows had nominal greater emissions per cow in the whole life, similar emissions per d of life and nearly 3% lower GWP, AP and EP per kg of fat plus protein yielded in lifespan. Income over feed costs per unit of emission tended to be nearly 4% greater in CR compared with HO cows. Also the use of land tended to be lower in CR compared with HO in most indicators considered. In conclusion, LCA could be adapted to represent individual animals. Moreover, managing dairy cows according to a 3-breed rotational crossbreeding scheme may be regarded as a strategy that can contribute to mitigate the emissions and to improve the environmental impact of dairy operations.

Effect of obesity on the exposure of long-acting cabotegravir and rilpivirine: a modelling study

BACKGROUND

Obesity is increasingly prevalent among people with HIV (PWH). Obesity can reduce drug exposure; however, limited data are available for long-acting (LA) antiretrovirals. We performed in-silico trials using physiologically based pharmacokinetic (PBPK) modelling to determine the effect of obesity on the exposure of LA cabotegravir and rilpivirine after the initial injection and after multiple injections.

METHODS

Our PBPK model was verified against available clinical data for LA cabotegravir and rilpivirine in normal weight/overweight (body mass index (BMI) < 30 kg/m2) and in obese (BMI ≥30 kg/m2). Cohorts of virtual individuals were generated to simulate the exposure of LA cabotegravir/rilpivirine up to a BMI of 60 kg/m2. The fold change in LA cabotegravir and rilpivirine exposures (AUC) and trough concentrations (Cmin) for monthly and bimonthly administration were calculated for various BMI categories relative to normal weight (18.5-25 kg/m2).

RESULTS

Obesity was predicted to impact more cabotegravir than rilpivirine with a decrease in cabotegravir AUC and Cmin of >35% for BMI >35 kg/m2 and in rilpivirine AUC and Cmin of >18% for BMI >40 kg/m2 at steady-state. A significant proportion of morbidly obese individuals were predicted to have both cabotegravir and rilpivirine Cmin below the target concentration at steady-state with the bimonthly administration but this was less frequent with the monthly administration.

CONCLUSIONS

Morbidly obese PWH are at risk of presenting suboptimal Cmin for cabotegravir/rilpivirine after the first injection but also at steady-state particularly with the bimonthly administration. Therapeutic drug monitoring is advised to guide dosing interval adjustment.

Antiretroviral Drug Exposure and Response in Obese and Morbidly Obese People With Human Immunodeficiency Virus (HIV): A Study Combining Modelling and Swiss HIV Cohort Data

BACKGROUND

Obesity is increasingly prevalent among people with HIV (PWH) and can possibly result in suboptimal antiretroviral drug (ARV) exposure and response. However, this has not been thoroughly evaluated given that obese PWH are underrepresented in clinical trials. We performed virtual trials using physiologically based pharmacokinetic (PBPK) modelling combined with observed clinical data to provide ARV dosing guidance in obese individuals.

METHODS

Each trial included a cohort of virtual adults with a body mass index (BMI) between 18.5 and 60 kg/m2. Therapeutic drug-monitoring data from the Swiss HIV Cohort Study (SHCS) were used to verify the predictive performance of the model. Subsequently, the model was applied to predict the pharmacokinetics of ARVs for different obesity classes. The association between ARV plasma concentrations and virological response was investigated in obese and nonobese individuals.

RESULTS

The PBPK model predicted an average reduction in ARV exposure of ∼20% and trough concentrations of ∼6% in obese (BMI ≥30 kg/m2) compared with nonobese (BMI: 18.5-25 kg/m2) individuals, consistent with observed clinical data. Etravirine and rilpivirine were the most impacted, especially in individuals with BMI >40 kg/m2 whose trough concentrations were below the clinical target threshold. Obese PWH in the SHCS did not have a higher rate of unsuppressed viral load than nonobese PWH.

CONCLUSIONS

The concentrations of ARVs are modestly reduced in obese individuals, with no negative impact on the virological response. Our data provide reassurance that standard doses of ARVs are suitable in obese PWH, including those who gained substantial weight with some of the first-line ARVs.

Intramuscular cabotegravir and rilpivirine concentrations after switching from efavirenz-containing regimen

AIMS

Intramuscular cabotegravir/rilpivirine (IM CAB/RPV) are metabolized by UGT1A1/CYP3A4. Efavirenz induces both enzymes; therefore, switching from an efavirenz-containing regimen to IM CAB/RPV could possibly result in suboptimal levels. Due to their long dosing interval, clinical studies with IM CAB/RPV are challenging. We used physiologically based pharmacokinetics (PBPK) modelling to simulate the switch from efavirenz to IM CAB/RPV.

METHODS

First, we developed the drug models and verified the performance of the PBPK model to predict the pharmacokinetics of IM cabotegravir, IM rilpivirine and efavirenz by comparing the simulations against observed clinical data. Second, we verified the ability of the model to predict the effect of residual induction with observed data for the switch from efavirenz to dolutegravir or rilpivirine. Finally, we generated a cohort of 100 virtual individuals (20-50 years, 50% female, 18.5-30 kg/m2 ) to simulate IM CAB/RPV concentrations after discontinuing efavirenz in extensive and slow metabolizers of efavirenz.

RESULTS

IM CAB concentrations were predicted to decrease by 11% (95% confidence interval 7-15%), 13% (6-21%) and 8% (0-18%) at day 1, 7 and 14 after efavirenz discontinuation. CAB concentrations were predicted to remain above the minimal efficacy threshold (i.e., 664 ng/mL) throughout the switch period both in extensive and slow metabolizers of efavirenz. Similarly, IM RPV concentrations were modestly decreased with the lowest reduction being 10% (6-14%) on day 7 post last efavirenz dose.

CONCLUSION

Our simulations indicate that switching from an efavirenz-containing regimen to IM CAB/RPV does not put at risk of having a time window with suboptimal drug levels.

Impact of Obesity on the Drug-Drug Interaction Between Dolutegravir and Rifampicin or Any Other Strong Inducers

Background

Obesity is increasingly prevalent among people with HIV. Obesity can impact drug pharmacokinetics and consequently the magnitude of drug-drug interactions (DDIs) and, thus, the related recommendations for dose adjustment. Virtual clinical DDI studies were conducted using physiologically based pharmacokinetic (PBPK) modeling to compare the magnitude of the DDI between dolutegravir and rifampicin in nonobese, obese, and morbidly obese individuals.

Methods

Each DDI scenario included a cohort of virtual individuals (50% female) between 20 and 50 years of age. Drug models for dolutegravir and rifampicin were verified against clinical observed data. The verified models were used to simulate the concurrent administration of rifampicin (600 mg) at steady state with dolutegravir (50 mg) administered twice daily in normal-weight (BMI 18.5-30 kg/m²), obese (BMI 30-40 kg/m²), and morbidly obese (BMI 40-50 kg/m²) individuals.

Results

Rifampicin was predicted to decrease dolutegravir area under the curve (AUC) by 72% in obese and 77% in morbidly obese vs 68% in nonobese individuals; however, dolutegravir trough concentrations were reduced to a similar extent (83% and 85% vs 85%). Twice-daily dolutegravir with rifampicin resulted in trough concentrations always above the protein-adjusted 90% inhibitory concentration for all BMI groups and above the 300 ng/mL threshold in a similar proportion for all BMI groups.

Conclusions

The combined effect of obesity and induction by rifampicin was predicted to further decrease dolutegravir exposure but not the minimal concentration at the end of the dosing interval. Thus, dolutegravir 50 mg twice daily with rifampicin can be used in individuals with a high BMI up to 50 kg/m².

Management of Drug Interactions with Inducers: Onset and Disappearance of Induction on Cytochrome P450 3A4 and Uridine Diphosphate Glucuronosyltransferase 1A1 Substrates

BACKGROUND

People living with HIV may present co-morbidities requiring the initiation and subsequently the discontinuation of medications with inducing properties. The time to reach maximal enzyme induction and to return to baseline enzyme levels has not been thoroughly characterized.

OBJECTIVE

The aim of this study was to evaluate the onset and disappearance of dolutegravir [uridine diphosphate glucuronosyltransferase (UGT) 1A1 and cytochrome P450 (CYP) 3A4 substrate] and raltegravir (UGT1A1 substrate) induction with strong and moderate inducers using physiologically based pharmacokinetic (PBPK) modeling.

METHODS

The predictive performance of the PBPK model to simulate dolutegravir and raltegravir pharmacokinetics and to reproduce the strength of induction was verified using clinical drug-drug interaction studies (steady-state induction) and switch studies (residual induction). The model was considered verified when the predictions were within 2-fold of the observed data. One hundred virtual individuals (50% female) were generated to simulate the unstudied scenarios. The results were used to calculate the fold-change in CYP3A4 and UGT1A1 enzyme levels upon initiation and discontinuation of strong (rifampicin) or moderate (efavirenz or rifabutin) inducers.

RESULTS

The time for reaching maximal induction and subsequent disappearance of CYP3A4 induction was 14 days for rifampicin and efavirenz but 7 days for rifabutin. The distinct timelines for the moderate inducers relate to their different half-lives and plasma concentrations. The induction and de-induction processes were more rapid for UGT1A1.

CONCLUSIONS

Our simulations support the common practice of maintaining the adjusted dosage of a drug for another 2 weeks after stopping an inducer. Furthermore, our simulations suggest that an inducer should be administered for at least 14 days before conducting interaction studies to reach maximal induction.

Optical polarization from colliding stellar stream shocks in a tidal disruption event

A tidal disruption event (TDE) occurs when a supermassive black hole rips apart a passing star. Part of the stellar material falls toward the black hole, forming an accretion disk that in some cases launches a relativistic jet. We performed optical polarimetry observations of a TDE, AT 2020mot. We find a peak linear polarization degree of 25 ± 4%, consistent with highly polarized synchrotron radiation, as is typically observed from relativistic jets. However, our radio observations, taken up to 8 months after the optical peak, do not detect the corresponding radio emission expected from a relativistic jet. We suggest that the linearly polarized optical emission instead arises from shocks that occur during accretion disk formation, as the stream of stellar material collides with itself.

Physiologically Based Pharmacokinetic Modelling to Identify Physiological and Drug Parameters Driving Pharmacokinetics in Obese Individuals

BACKGROUND

Obese individuals are often underrepresented in clinical trials, leading to a lack of dosing guidance.

OBJECTIVE

This study aimed to investigate which physiological parameters and drug properties determine drug disposition changes in obese using our physiologically based pharmacokinetic (PBPK) framework, informed with obese population characteristics.

METHODS

Simulations were performed for ten drugs with clinical data in obese (i.e., midazolam, triazolam, caffeine, chlorzoxazone, acetaminophen, lorazepam, propranolol, amikacin, tobramycin, and glimepiride). PBPK drug models were developed and verified first against clinical data in non-obese (body mass index (BMI) ≤ 30 kg/m²) and subsequently in obese (BMI ≥ 30 kg/m²) without changing any drug parameters. Additionally, the PBPK model was used to study the effect of obesity on the pharmacokinetic parameters by simulating drug disposition across BMI, starting from 20 up to 60 kg/m².

RESULTS

Predicted pharmacokinetic parameters were within 1.25-fold (71.5%), 1.5-fold (21.5%) and twofold (7%) of clinical data. On average, clearance increased by 1.6% per BMI unit up to 64% for a BMI of 60 kg/m², which was explained by the increased hepatic and renal blood flows. Volume of distribution increased for all drugs up to threefold for a BMI of 60 kg/m²; this change was driven by pK_a for ionized drugs and logP for neutral and unionized drugs. C_max decreased similarly across all drugs while t_max remained unchanged.

CONCLUSION

Both physiological changes and drug properties impact drug pharmacokinetics in obese subjects. Clearance increases due to enhanced hepatic and renal blood flows. Volume of distribution is higher for all drugs, with differences among drugs depending on their pK_a/logP.

Management of drug-drug interactions between long-acting cabotegravir and rilpivirine and comedications with inducing properties: a modelling study

Background

Long-acting (LA) intramuscular cabotegravir and rilpivirine are prone to drug-drug interactions (DDI). However, given the long dosing interval, the conduct of clinical DDIs studies with LA antiretrovirals is challenging. We performed virtual clinical DDI studies using physiologically based pharmacokinetic (PBPK) modelling to provide recommendations for the management of DDIs with strong or moderate inducers such as rifampicin or rifabutin.

Methods

Each DDI scenario included a cohort of virtual individuals (50% female) between 20-50 years of age with a body mass index of 18-30 kg/m2. Cabotegravir and rilpivirine were given alone and in combination with rifampicin or rifabutin. The predictive performance of the PBPK model to simulate cabotegravir and rilpivirine pharmacokinetics after oral and intramuscular administration and to reproduce DDIs with rifampicin and rifabutin was first verified against available observed clinical data. The verified model was subsequently used to simulate unstudied DDI scenarios.

Results

At steady-state, the strong inducer rifampicin was predicted to decrease the area under the curve (AUC) of LA cabotegravir by 61% and rilpivirine by 38%. An increase in the dosing frequency did not overcome the DDI with rifampicin. The moderate inducer rifabutin was predicted to reduce the AUC of LA cabotegravir by 16% and rilpivirine by 18%. The DDI with rifabutin can be overcome by administering LA cabotegravir/rilpivirine monthly together with a daily oral rilpivirine dose of 25 mg.

Conclusion

LA cabotegravir/rilpivirine should be avoided with strong inducers but coadministration with moderate inducers is possible by adding oral rilpivirine daily dosing to the monthly injection.

Repository Describing the Anatomical, Physiological, and Biological Changes in an Obese Population to Inform Physiologically Based Pharmacokinetic Models

Background

Obesity is associated with physiological changes that can affect drug pharmacokinetics. Obese individuals are underrepresented in clinical trials, leading to a lack of evidence-based dosing recommendations for many drugs. Physiologically based pharmacokinetic (PBPK) modelling can overcome this limitation but necessitates a detailed description of the population characteristics under investigation.

Objective

The purpose of this study was to develop and verify a repository of the current anatomical, physiological, and biological data of obese individuals, including population variability, to inform a PBPK framework.

Methods

A systematic literature search was performed to collate anatomical, physiological, and biological parameters for obese individuals. Multiple regression analyses were used to derive mathematical equations describing the continuous effect of body mass index (BMI) within the range 18.5–60 kg/m² on system parameters.

Results

In total, 209 studies were included in the database. The literature reported mostly BMI-related changes in organ weight, whereas data on blood flow and biological parameters (i.e. enzyme abundance) were sparse, and hence physiologically plausible assumptions were made when needed. The developed obese population was implemented in Matlab^® and the predicted system parameters obtained from 1000 virtual individuals were in agreement with observed data from an independent validation obese population. Our analysis indicates that a threefold increase in BMI, from 20 to 60 kg/m², leads to an increase in cardiac output (50%), liver weight (100%), kidney weight (60%), both the kidney and liver absolute blood flows (50%), and in total adipose blood flow (160%).

Conclusion

The developed repository provides an updated description of a population with a BMI from 18.5 to 60 kg/m² using continuous physiological changes and their variability for each system parameter. It is a tool that can be implemented in PBPK models to simulate drug pharmacokinetics in obese individuals.

Natural sesame oil is superior to pre-digested lipid formulations and purified triglycerides in promoting the intestinal lymphatic transport and systemic bioavailability of cannabidiol

Lipid-based formulations play a significant role in oral delivery of lipophilic drugs. Previous studies have shown that natural sesame oil promotes the intestinal lymphatic transport and oral bioavailability of the highly lipophilic drug cannabidiol (CBD). However, both lymphatic transport and systemic bioavailability were also associated with considerable variability. The aim of this study was to test the hypothesis that pre-digested lipid formulations (oleic acid, linoleic acid, oleic acid with 2-oleoylglycerol, oleic acid with 2-oleoylglycerol and oleic acid with glycerol) could reduce variability and increase the extent of the intestinal lymphatic transport and oral bioavailability of CBD. The in vivo studies in rats showed that pre-digested or purified triglyceride did not improve the lymphatic transport and bioavailability of CBD in comparison to sesame oil. Moreover, the results suggest that both the absorption of lipids and the absorption of co-administered CBD were more efficient following administration of natural sesame oil vehicle compared with pre-digested lipids or purified trioleate. Although multiple small molecule constituents and unique fatty acid compositions could potentially contribute to a better performance of sesame oil in oral absorption of lipids or CBD, further investigation will be needed to identify the mechanisms involved.

Early symptoms and long-term clinical outcomes of distal limb's cutaneous arterio-venous malformations: a retrospective multicentre study of 19 adult patients

INTRODUCTION

Cutaneous arterio-venous malformations (AVM) are high-flow vascular malformations made up of a direct link between arteries and veins without intermediary capillary space. 'Distal limb's AVM', which mean involving hands or feet, are rare and their functional prognosis is often poor. Little is known about their early clinical symptoms. The objectives of this study were to identify early clinical symptoms of distal limb's cutaneous AVMs and to determine their long-term clinical outcome.

METHODS

A retrospective study was carried out including adult patients who had distal limb's AVM, who were followed up between January 2000 and November 2013 in two regional tertiary care centres. The information was collected from patients' clinical records and completed by a structured telephone questionnaire.

RESULTS

Nineteen patients were included in the study: four (21%) with foot AVM and 15 (79%) with hand AVM. The first clinical symptoms were as follows: swelling (47%), pain (47%), one or several venous dilatations (37%) and rarely abnormal skin colour, hyperthermia and pulsating sensation. The median diagnosis delay was 9 years after the onset of first manifestations. Amongst the 17 patients who underwent a treatment, 53% had embolotherapy session(s), 12% surgery and 35% had both. After an average follow-up of 57.6 months, 31% of the 13 patients contacted who were receiving treatment were in complete remission; 31% had partial remission; 15% had relapse after initial improvement and 23% had treatment failure. Overall, 74% of patients had a serious development of the AVM: 37% had digital or hand amputation, and 42% remained symptomatic and/or unstable.

CONCLUSION

This study suggests that initial manifestations of distal limb's AVMs are discreet and non-specific, leading to a diagnosis delay of about 10 years, with poor prognosis. Doctors should evoke the diagnosis earlier, when these symptoms are shown: pain and/or swelling, sometimes with a large vein.

Efficacy and safety of patupilone in non-small cell lung cancer (NSCLC): A phase I/II trial

7104

Background: Based on its activity in a wide range of tumors including those that are taxane resistant, the novel microtubule stabilizer patupilone (EPO906; epothilone B) has the potential to treat NSCLC. Fifty patients were enrolled in phase I to evaluate safety, efficacy, and optimal dose. The phase II part of this study is investigating the antitumor activity of patupilone in 53 patients with stage IIIB/IV NSCLC. Methods: Patients with histologically or cytologically confirmed unresectable, locally advanced, or metastatic NSCLC documented before 1st-line therapy without symptomatic or uncontrolled brain metastases received patupilone at a starting dose of 10.0 mg/m2 q3wk by 20-minute IV infusion. Additional inclusion criteria: age ≥18 years; WHO performance status 0–1; prior treatment with a platinum-containing regimen. Primary objective of the phase II, single-arm, 2-stage, multicenter trial: to determine activity of patupilone q3wk (overall response using modified RECIST) in NSCLC. An additional cohort with recurrent brain metastases from NSCLC is being accrued to evaluate safety, pharmacokinetics, and activity. Results: In phase I, all patients received prior treatment with platinum therapy; 28% had received taxanes and 78% nontaxanes. Patupilone dose was escalated from 6.5 to 13.0 mg/m2 q3wk. Dose-limiting toxicities occurred in 4 patients: 1 with grade 3 asthenia and 3 with grade 3 diarrhea at various dose levels. The most frequent adverse events (AEs) were diarrhea (66%), nausea (40%), vomiting (34%), paraesthesia (32%), abdominal pain (30%), and fatigue (30%). The most frequent grade 3 AE was diarrhea (14%); a grade 4 AE (asthenia) occurred in 1 patient. Overall phase I response: 5 PR, 16 SD, and 26 PD. Based on risk-benefit analyses, 10.0 mg/m2 q3wk was recommended as the phase II dose. Phase II is ongoing: 25 of 53 patients (15 men and 6 women with NSCLC; 2 men and 2 women with brain metastases) have been enrolled. Conclusions: In phase I, patupilone q3wk was safe and well tolerated, with antitumor activity in patients with advanced pretreated NSCLC. Data from phase II will be available at time of presentation.

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Inhibition of HIV-1 in cell culture by oligonucleotide-loaded nanoparticles

PURPOSE

To investigate the potential use of polymeric nanoparticles for the delivery of antisense oligonucleotides in HIV-1-infected cell cultures.

METHODS

Phosphorothioate oligonucleotides were encapsulated into poly (D,L-lactic acid) nanoparticles. Two models of infected cells were used to test the ability of nanoparticles to deliver them. HeLa P4-2 CD4+ cells, stably transfected with the beta-galactosidase reporter gene, were first used to evaluate the activity of the oligonucleotides on a single-round infection cycle. The acutely infected lymphoid CEM cells were then used to evaluate the inhibition of the viral production of HIV-1 by the oligonucleotides.

RESULTS

The addition to infected CEM cells of nanoparticles containing gag antisense oligonucleotides in the nanomolar range led to strong inhibition of the viral production in a concentration-dependent manner. Similar results were previously observed in HeLa P4-2 CD4+ cells. Nanoparticle-entrapped random-order gag oligonucleotides had similar effects on reverse transcription. However, the reverse transcriptase activity of infected cells treated with nanomolar concentrations of free antisense and random oligonucleotides was not affected.

CONCLUSIONS

These results suggest that poly (D,L-lactic acid) nanoparticles may have great potential as an efficient delivery system for oligonucleotides in HIV natural target cells, i.e., lymphocytic cells.

Comparison of two methods of encapsulation of an oligonucleotide into poly(D,L-lactic acid) particles

The aim of this study was to compare two methods to encapsulate a 25-mer-phosphorothioate oligonucleotide (ODN) into poly(D,L-lactic acid) (PLA) particles. Antisense oligonucleotides belong to a new therapeutic class especially attractive for the treatment of cancers and viral diseases. The development of these new drugs suffers, however, from poor stability in biological media and very low cellular uptake. Polymeric particulate systems display interesting features for ODN delivery. ODN are highly hydrophilic and most encapsulation methods are inappropriate for such molecules. Using poly(D,L-lactide) polymer, two methods of encapsulation were compared. First, a double emulsion technique was used to prepare nano- and microparticles. Secondly, the ODN was combined with a quaternary ammonium, the cethyltrimethyl-ammonium bromide (CTAB), to enhance the hydrophobicity of the molecule before entrapment by the emulsification-diffusion method. Both methods led to the formation of individualized and spherical particles loaded with a significant amount of ODN. Similar entrapment efficiencies were obtained for the nanoparticles prepared by both methods (approx. 27% of the theoretical loading) whereas 45% of entrapment efficiency was observed for the microparticles. Seventy five percent of the ODN were released in 60 min with the particles prepared by the emulsification-diffusion method, whereas only 7% were released in 60 h when using the double emulsion method. A viability test on U-937 cells showed better survival rates with the particles prepared by the double emulsion technique. The results suggest that the location of the ODN in the polymeric matrix is affected by the encapsulation method. Particles containing CTAB appeared more toxic than the ones obtained by the double emulsion technique, however, these particles can still be used for antisense activity since high oligonucleotide loading can be achieved.

Highly loaded nanoparticulate carrier using an hydrophobic antisense oligonucleotide complex

Antisense oligonucleotides, and particularly those with phosphorothioate backbones, have emerged as potential gene specific therapeutic agents and are currently undergoing evaluation in clinical trials for a variety of diseases. In the area of HIV-1 therapeutics, targeting of oligonucleotides to infected cells, such as macrophages, would be highly desirable. The present study was designed to prepare and characterize oligonucleotide-loaded nanoparticles for this purpose. Due to their hydrophilic characteristics, oligonucleotides are difficult to entrap in polymeric particles. Here, the oligonucleotides were first complexed with cetyltrimethylammonium bromide. The oligonucleotide-loaded nanoparticles were prepared by the emulsification-diffusion method and subsequently purified. In comparison with previous studies, a high oligonucleotide-loading was achieved; 2.5, 5 and 10% oligonucleotide loading were assessed. If the initial oligonucleotide content was 4%, this method produced a final oligonucleotide loading of 1.9% with an entrapment efficiency of 47%. The integrity of the oligonucleotide and of the polymer, in the final freeze-dried product, was retained.

In vitro antibacterial activity of thiamphenicol glycinate acetylcysteinate against respiratory pathogens

After 30 years of therapeutic use, thiamphenicol glycinate acetylcysteinate (CAS 20192-91-0) is still widely employed in the treatment of upper and lower respiratory tract infections. This is due to its particular characteristic to exert at pulmonary level, either the antibacterial activity of thiamphenicol (CAS 15318-45-3) and the mucolytic activity of N-acetylcysteine (CAS 616-91-1). The aim of this study was to evaluate the present pattern of susceptibility of several clinical isolates to thiamphenicol and the interference of N-acetylcysteine on this parameter. The studies have been performed in vitro. Equimolar concentrations of N-acetylcysteine and even higher concentrations did not interfere with the antibacterial activity of thiamphenicol against Streptococcus pneumoniae, Streptococcus pyogenes and Haemophilus influenzae. The spectrum of activity of thiamphenicol was similar to that observed in the past and was superior to that of erythromycin and amoxicillin. The activity of thiamphenicol was greater than that of erythromycin against H. influenzae and streptococci and equivalent versus Branhamella catarrhalis. In comparison with amoxicillin the activity of thiamphenicol was higher against H. influenzae and B. catarrhalis and slightly lower against streptococci. The results demonstrate that thiamphenicol maintains its therapeutic value confirming the importance of thiamphenicol glycinate acetylcysteinate in the treatment of respiratory tract infections.

Uptake of oligonucleotide-loaded nanoparticles in prostatic cancer cells and their intracellular localization

The development of antisense biotechnology is dependent, in part, on creating improved methods for delivering oligonucleotides to cells. In this study, we investigated a colloidal system (nanoparticles (NP) of poly (D,L) lactic acid) that affects the intracellular delivery of oligonucleotides. We have examined the intracellular compartmentalization in DU145 cells of fluorescein labeled phosphorothioate oligonucleotides, both in the free state and when loaded into NP. Fluorescent oligonucleotides were incubated for 18 h with DU145 cells and the mean intracellular fluorescence was determined by flow cytometry. After the addition of monensin, an increase in signal intensity was observed, indicating that free oligonucleotides were resident in an acidic intracellular environment, whereas oligonucleotides from the NP did not reside in an acidic compartment. Free and NP loaded with oligonucleotides effluxed from DU145 cells from two intracellular compartments. This preliminary report indicates that colloidal carriers such as NP could prove to be useful in affecting intracellular trafficking of oligonucleotides in DU145 and in other cells.

Formation of a G-tetrad and higher order structures correlates with biological activity of the RelA (NF-kappaB p65) 'antisense' oligodeoxynucleotide

We have examined the behavior of the phosphorothioate antisense Rel A (NF-kappaB p65) oligodeoxynucleotide (oligo) and related molecules. Because of the presence of a G-tetrad near its 5'terminus, this molecule is capable of forming tetraplexes and other higher order structures in a temperature and time dependent manner. The G-tetrad in the phosphodiester congener is protected from methylation by dimethylsulfate when the oligomer is 3'-phosphorylated. However, this protection is completely lost when it is 5'phosphorylated, indicating that the formation of at least some higher order structures has been blocked. In addition, we also prevented tetraplex formation by substitution of 7-deazaguanosine (7-DG) for guanosine at several positions within and outside of the tetrad. This substitution retains Watson-Crick base pair hybridization but prevents Hoogsteen base-pair interactions. When murine K-Balb cells were treated with 20microM antisense RelA oligo, complete blockade of nuclear translocation of RelA was observed. However, this effect was virtually entirely abrogated in most cases by 7-DG substitution within the tetrad, but retained when the substitution was made 3' to the tetrad. The AS RelA-induced downregulation of Sp-1 activity behaved similarly after 7-DG substitution. Thus, the parent phosphorothioate AS RelA molecule cannot be a Watson-Crick antisense agent. However, these conclusions cannot be extrapolated to other G-tetrad containing oligomers and each must be evaluated individually.

Applying what burn survivors have to say to future therapeutic interventions

Statements by caregivers can be beneficial to paediatric burn patients, facilitating their psychological adaptation. However, the concerns of the burned child are not always obvious, and caregivers may flounder, not knowing how to elicit the concerns of the patient. The purpose of this paper is to examine whether universal concerns of the postburn survivor can be detected through one type of psychological assessment tool, a sentence completion task. Sixty paediatric burn survivors, ages 6-19, were administered a 30-item Incomplete Sentences measure. Five major aspects of postburn life were identified and proscribed the following descriptive labels: (1) preoccupation with health; (2) the struggle for internal acceptance; (3) reconstruction of one's life map; (4) changing relationships; and (5) redefining the world. These five dimensions of postburn life are discussed, as well as applications for each.

Improved oligonucleotide uptake and stability by a new drug carrier, the SupraMolecular Bio Vector (SMBV)

Antisense oligodeoxynucleotides are potential therapeutic agents, but their development is still limited by both a poor cellular uptake and a high degradation rate in biological media. The strategy that we propose to face these problems is to use small synthetic carriers, around 30 nm diameter, the SupraMolecular Bio Vectors (SMBV). We used positively charged SMBV and settled the ionic incorporation of negatively charged oligonucleotides into these carriers. A minimal leakage of 10% of total incorporated oligonucleotides was then measured during two months. Both protection and uptake of oligonucleotides were then analyzed. On the one hand, we showed that the incorporation of oligonucleotides into the selected SMBV allows to significantly increase, 8 times, their half-life, in cell growth medium. On the other hand, the internalization of the SMBV, into cells, by an endosomal pathway has been characterized. The essential point is that the SMBV uptake elicits the simultaneous oligonucleotide uptake. The oligonucleotide amount that goes through cells within 5 h can be up to 30 times higher than for free oligonucleotides and the fraction of oligonucleotides that is present in the cytosol is increased up to 10 fold after incorporation into the SMBV. This study demonstrates the ability of SMBV to improve oligonucleotide cellular behaviour.

[Synthesis and tests of antibacterial activity of new analogs of d(+)-threo-1-(p-methylsulphonylphenyl)-2-dichloroacetamido-1,3-propanediol (thiamphenicol)]

The synthesis of three new analogues of D(+)-threo-1-(p.methylsulphonylphenyl)-2-dichloroacetamido-1,3-propanediol (thiamphenicol) (I) which are D(--)-threo-2-(p.toluensulfophonamido)-1-(p.methylsulphonylphenyl)-1,3-propanediol (II), D(--)-threo-2-(p.aminobenzensulphonamido)-1-(p.methylsulphonylphenyl)-1,3-propanediol (III), D(--)-threo-2-(p.acetamidobenzensulphonamido)-1-(p.methylsulphonylphenyl)-1,3-propandiol (IV) is reported. The antibacterial activity of the compounds obtained was estimated in comparison with (I) in vitro and the therapeutic activity in vivo by experimental infection of the rat. The results showed the total absence of both types of activity.