Clinical Pharmacology Perspective on Development of Adeno-Associated Virus Vector-Based Retina Gene Therapy.

Adeno-associated virus (AAV) vector-based gene therapy is an innovative modality being increasingly investigated to treat diseases by modifying or replacing defective genes or expressing therapeutic entities. With its unique anatomic and physiological characteristics, the eye constitutes a very attractive target for gene therapy. Specifically, the ocular space is easily accessible and is generally considered "immune-privileged" with a low risk of systemic side effects following local drug administration. As retina cells have limited cellular turnover, a one-time gene delivery has the potential to provide long-term transgene expression. Despite the initial success with voretigene neparvovec (Luxturna), the first approved retina gene therapy, there are still challenges to be overcome for successful clinical development of these products and scientific questions to be answered. The current review paper aims to integrate published experience learned thus far for AAV-based retina gene therapy related to preclinical to clinical translation; first-in-human dose selection; relevant bioanalytical assays and strategies; clinical development considerations including trial design, biodistribution and vector shedding, immunogenicity, transgene expression, and pediatric populations; opportunities for model-informed drug development; and regulatory perspectives. The information presented herein is intended to serve as a guide to inform the clinical development strategy for retina gene therapy with a focus on clinical pharmacology.

Best Practices and Considerations for Clinical Pharmacology and Pharmacometric Aspects for Optimal Development of CAR-T and TCR-T Cell Therapies: An Industry Perspective.

With the promise of a potentially "single dose curative" paradigm, CAR-T cell therapies have brought a paradigm shift in the treatment and management of hematological malignancies. Both CAR-T and TCR-T cell therapies have also made great progress toward the successful treatment of solid tumor indications. The field is rapidly evolving with recent advancements including the clinical development of "off-the-shelf" allogeneic CAR-T therapies that can overcome the long and difficult "vein-to-vein" wait time seen with autologous CAR-T therapies. There are unique clinical pharmacology, pharmacometric, bioanalytical, and immunogenicity considerations and challenges in the development of these CAR-T and TCR-T cell therapies. Hence, to help accelerate the development of these life-saving therapies for the patients with cancer, experts in this field came together under the umbrella of International Consortium for Innovation and Quality in Pharmaceutical Development (IQ) to form a joint working group between the Clinical Pharmacology Leadership Group (CPLG) and the Translational and ADME Sciences Leadership Group (TALG). In this white paper, we present the IQ consortium perspective on the best practices and considerations for clinical pharmacology and pharmacometric aspects toward the optimal development of CAR-T and TCR-T cell therapies.

Nonclinical Development of Next-generation Site-specific HER2-targeting Antibody-drug Conjugate (ARX788) for Breast Cancer Treatment.

Conventional antibody-drug conjugates (ADC) utilize native surface-exposed lysines or cysteines on the antibody of interest to conjugate cytotoxic payload. The nonspecific conjugation results in a mixture with variable drug-to-antibody ratios (DAR), conjugation sites, and ADCs that are often unstable in systemic circulation. ARX788 is an ADC consisting of a HER2-targeting antibody site-specifically conjugated with a potent antitubulin cytotoxic drug-linker, AS269. The site-specific conjugation is achieved by first incorporating the nonnatural amino acid, para-acetyl phenylalanine (pAF), into the antibody, followed by covalent conjugation of AS269 to the pAF to form a highly stable oxime bond resulting in a DAR 2 ADC. ARX788 exhibits significant, dose-dependent antitumor activity against HER2- expressing breast and gastric xenograft tumors. Pharmacokinetic (PK) studies in multiple species showed the highly stable nature of ARX788 with overlapping PK profiles for the intact ADC and total antibody. Metabolism studies demonstrated that pAF-AS269 was the sole major metabolite of ARX788, with no evidence for the release of free drug often observed in conventional ADCs and responsible for adverse side effects. Furthermore, ARX788 demonstrated a favorable safety profile in monkeys with a highest nonseverely toxic dose of 10 mg/kg, which was well above the efficacious dose level observed in preclinical tumor models, thus supporting clinical development of ARX788.

Pulmonary Administration of Microparticulate Antisense Oligonucleotide (ASO) for the Treatment of Lung Inflammation.

Targeted delivery to the lung for controlling lung inflammation is an area that we have explored in this study. The purpose was to use microparticles containing an antisense oligonucleotide (ASO) to NF-κB to inhibit the production of proinflammatory cytokines. Microparticles were prepared using the B-290 Buchi Spray Dryer using albumin as the microparticle matrix. Physicochemical characterization of the microparticles showed the size ranged from 2 to 5 µm, the charge was - 38.4 mV, and they had a sustained release profile over 72 h. Uptake of FITC-labeled ASO-loaded microparticles versus FITC-labeled ASO solution by RAW264.7 murine macrophage cells was 5-10-fold higher. After pulmonary delivery of microparticles to Sprague-Dawley rats, the microparticles were uniformly distributed throughout the lung and were retained in the lungs until 48 h. Serum cytokine (TNF-α and IL-1ß) levels of rats after induction of lung inflammation by lipopolysaccharide were measured until 72 h. Animals receiving ASO-loaded microparticles were successful in significantly controlling lung inflammation during this period as compared to animals receiving no treatment. This study was successful in proving that microparticulate ASO therapy was capable of controlling lung inflammation.

Increased bioavailability of celecoxib under fed versus fasted conditions is determined by postprandial bile secretion as demonstrated in a dynamic gastrointestinal model.

The objective of this study was to utilize physiologically relevant dynamic dissolution testing with the TNO intestinal model (TIM-1) in vitro gastrointestinal model to investigate the bioaccessibility of celecoxib. A single 200-mg dose of celecoxib was evaluated under average adult human physiological conditions simulated in the TIM-1 system. The in vitro data were compared with the clinically established pharmacokinetic data. When expressed as a percent of drug that progresses from the duodenum to the jejunum and ileum compartments (bioaccessible sites), the study demonstrated a 2-fold increase in the total bioaccessibility for celecoxib when co-administered with a high-fat meal as opposed to co-administration with a glass of water (fasted conditions). That increase in bioaccessibility was similar to a 1.2 to 1.6-fold increase in systemic exposure in adults and children following co-administration with a high-fat meal when compared to the exposure measured when celecoxib was co-administered with only water. Following that comparison, the flexibility of the TIM-1 system was used to more specifically investigate individual parameters of gastrointestinal conditions, such as the rate of bile secretion (emptying of the bile bladder) that accompanies high-fat meal consumption. We demonstrated that increased bile secretion after co-administration of a high-fat meal played a more important role in the increased celecoxib bioaccessibility than did the food matrix. This indicates that in humans without a bile bladder the exposure of celecoxib administered with food might be as low as under fasted state.

Implementation of mixture design for formulation of albumin containing enteric-coated spray-dried microparticles.

CONTEXT: Oral delivery of proteins has been a challenging as well as rapidly developing field. OBJECTIVE: To implement mixture design of experiment to develop enteric-coated microparticles containing bovine serum albumin. MATERIALS AND METHODS: Microparticles were prepared using Buchi Spray Dryer 191. Simplex lattice mixture design computed using JMP software was implemented to compare the gastric protection rendered by Eudragit FS30D, Eudragit L100-55, and Eudragit S100 in microparticulate form. Further, an extreme vertices mixture design was used to incorporate hydroxypropyl methylcellulose (HPMC) Chitosan in the formulation to delay the release. Microparticle recovery yield and protein content in microparticles were evaluated. RESULTS AND DISCUSSIONS: The design was statistically significant with Eudragit S100 resulting in protein release of < 5% in acidic buffer. The selected optimal formulation had 70% of Eudragit S, 25% HPMC, and 5% Chitosan. The release profiles of protein from Eudragit S alone and along with HPMC were compared. About 25% decrease in the amount of protein release was observed 6 h post exposure of microparticle to buffer of pH 6.8. The microparticle recovery yield reduced from 77.99% to 71.56% which is due to addition of HPMC into the formulation matrix. CONCLUSION: Although all three Eudragit polymers can be used for enteric coating, in the microparticulate form Eudragit S resulted in higher gastric protection. Also use of HPMC along with Eudragit S resulted in further sustained release.

Immunogenicity and protection of oral influenza vaccines formulated into microparticles.

Influenza is a deadly disease affecting humans and animals. It is recommended that every individual should be vaccinated annually against influenza. Considering the frequency of administration of this vaccine, we have explored the oral route of vaccination with a microparticulate formulation. Microparticles containing inactivated influenza A/PR/34/8 H1N1 virus with Eudragit S and trehalose as a matrix were prepared using the Buchi spray dryer. Particle size distribution of microparticles was measured and the bioactivity of vaccine in a microparticle form was analyzed using a hemagglutination activity test. Furthermore, the efficacy of microparticle vaccines was evaluated in vivo in Balb/c mice. Analysis of serum samples showed that microparticles resulted in enhanced antigen-specific immunoglobulin G (IgG), IgG1, and IgG2a antibodies. Upon challenge with homologous and heterologous influenza viruses, microparticle vaccines showed significantly increased levels of protection. Use of microparticles to deliver vaccines could be a promising tool for the development of an oral influenza vaccine.