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.

PK/PD and Bioanalytical Considerations of AAV-Based Gene Therapies: an IQ Consortium Industry Position Paper.

Interest and efforts to use recombinant adeno-associated viruses (AAV) as gene therapy delivery tools to treat disease have grown exponentially. However, gaps in understanding of the pharmacokinetics/pharmacodynamics (PK/PD) and disposition of this modality exist. This position paper comes from the Novel Modalities Working Group (WG), part of the International Consortium for Innovation and Quality in Pharmaceutical Development (IQ). The pan-industry WG effort focuses on the nonclinical PK and clinical pharmacology aspects of AAV gene therapy and related bioanalytical considerations.Traditional PK concepts are generally not applicable to AAV-based therapies due to the inherent complexity of a transgene-carrying viral vector, and the multiple steps and analytes involved in cell transduction and transgene-derived protein expression. Therefore, we explain PK concepts of biodistribution of AAV-based therapies and place key terminologies related to drug exposure and PD in the proper context. Factors affecting biodistribution are presented in detail, and guidelines are provided to design nonclinical studies to enable a stage-gated progression to Phase 1 testing. The nonclinical and clinical utility of transgene DNA, mRNA, and protein analytes are discussed with bioanalytical strategies to measure these analytes. The pros and cons of qPCR vs. ddPCR technologies for DNA/RNA measurement and qualitative vs. quantitative methods for transgene-derived protein are also presented. Last, best practices and recommendations for use of clinical and nonclinical data to project human dose and response are discussed. Together, the manuscript provides a holistic framework to discuss evolving concepts of PK/PD modeling, bioanalytical technologies, and clinical dose selection in gene therapy.

International consortium for innovation and quality: An industry perspective on the nonclinical and early clinical development of intravitreal drugs.

The eye, which is under constant exposure to environmental pathogens, has evolved various anatomic and immunological barriers critical to the protection of tissues lacking regenerative capacity, and the maintenance of a clear optic pathway essential to vision. By bypassing the ocular barriers, intravitreal (IVT) injection has become the mainstay for the delivery of drugs to treat conditions that affect the back of the eye. Both small molecules and biotherapeutics have been successfully administered intravitreally, and several drugs have been approved for the treatment of (wet) age-related macular degeneration and diabetic macular edema. However, IVT injection is an invasive procedure, which requires sufficient technical expertise from the healthcare professional administering the drug. Potential side effects include bleeding, retinal tear, cataracts, infection, uveitis, loss of vision, and increased ocular pressure. Pharmaceutical companies often differ in their drug development plan, including drug administration techniques, collection of ocular tissues and fluids, ophthalmology monitoring, and overall conduct of nonclinical and clinical studies. The present effort, under the aegis of the Innovation & Quality Ophthalmic Working Group, aims at understanding these differences, identifying pros and cons of the various approaches, determining the gaps in knowledge, and suggesting feasible good practices for nonclinical and early clinical IVT drug development.

Nanoparticle biodistribution coefficients: A quantitative approach for understanding the tissue distribution of nanoparticles.

The objective of this manuscript is to provide quantitative insights into the tissue distribution of nanoparticles. Published pharmacokinetics of nanoparticles in plasma, tumor and 13 different tissues of mice were collected from literature. A total of 2018 datasets were analyzed and biodistribution of graphene oxide, lipid, polymeric, silica, iron oxide and gold nanoparticles in different tissues was quantitatively characterized using Nanoparticle Biodistribution Coefficients (NBC). It was observed that typically after intravenous administration most of the nanoparticles are accumulated in the liver (NBC = 17.56 %ID/g) and spleen (NBC = 12.1 %ID/g), while other tissues received less than 5 %ID/g. NBC values for kidney, lungs, heart, bones, brain, stomach, intestine, pancreas, skin, muscle and tumor were found to be 3.1 %ID/g, 2.8 %ID/g, 1.8 %ID/g, 0.9 %ID/g, 0.3 %ID/g, 1.2 %ID/g, 1.8 %ID/g, 1.2 %ID/g, 1.0 %ID/g, 0.6 %ID/g and 3.4 %ID/g, respectively. Significant variability in nanoparticle distribution was observed in certain organs such as liver, spleen and lungs. A large fraction of this variability could be explained by accounting for the differences in nanoparticle physicochemical properties such as size and material. A critical overview of published nanoparticle physiologically-based pharmacokinetic (PBPK) models is provided, and limitations in our current knowledge about in vitro and in vivo pharmacokinetics of nanoparticles that restrict the development of robust PBPK models is also discussed. It is hypothesized that robust quantitative assessment of whole-body pharmacokinetics of nanoparticles and development of mathematical models that can predict their disposition can improve the probability of successful clinical translation of these modalities.

The Perspective of DMPK on Recombinant Adeno-Associated Virus-Based Gene Therapy: Past Learning, Current Support, and Future Contribution.

Given the recent success of gene therapy modalities and the growing number of cell and gene-based therapies in clinical development across many different therapeutic areas, it is evident that this evolving field holds great promise for the unmet medical needs of patients. The recent approvals of Luxturna® and Zolgensma® prove that recombinant adeno-associated virus (rAAV)-based gene therapy is a transformative modality that enables curative treatment for genetic disorders. Over the last decade, Takeda has accumulated significant experience with rAAV-based gene therapies, especially in the early stage of development. In this review, based on the learnings from Takeda and publicly available information, we aim to provide a guiding perspective on Drug Metabolism and Pharmacokinetics (DMPK) substantial role in advancing therapeutic gene therapy modalities from nonclinical research to clinical development, in particular the characterization of gene therapy product biodistribution, elimination (shedding), immunogenicity assessment, multiple platform bioanalytical assays, and first-in-human (FIH) dose projection strategies. Graphical abstract.

Distribution of topical ocular nepafenac and its active metabolite amfenac to the posterior segment of the eye.

Nepafenac ophthalmic suspensions, 0.1% (NEVANAC(®)) and 0.3% (ILEVRO™), are topical nonsteroidal anti-inflammatory drug (NSAID) products approved in the United States, Europe and various other countries to treat pain and inflammation associated with cataract surgery. NEVANAC is also approved in Europe for the reduction in the risk of postoperative macular edema (ME) associated with cataract surgery in diabetic patients. The efficacy against ME suggests that topical administration leads to distribution of nepafenac or its active metabolite amfenac to the posterior segment of the eye. This article evaluates the ocular distribution of nepafenac and amfenac and the extent of local delivery to the posterior segment of the eye, following topical ocular instillation in animal models. Nepafenac ophthalmic suspension was instilled unilaterally in New Zealand White rabbits as either a single dose (0.1%; one drop) or as multiple doses (0.3%, one drop, once-daily for 4 days, or 0.1% one drop, three-times daily for 3 days and one morning dose on day 4). Nepafenac (0.3%) was also instilled unilaterally in cynomolgus monkeys as multiple doses (one drop, three-times daily for 7 days). Nepafenac and amfenac concentrations in harvested ocular tissues were measured using high-performance liquid chromatography/mass spectrometry. Locally-distributed compound concentrations were determined as the difference in levels between dosed and undosed eyes. In single-dosed rabbit eyes, peak concentrations of locally-distributed nepafenac and amfenac showed a trend of sclera > choroid > retina. Nepafenac peak levels in sub-samples posterior to the eye equator and inclusive of the posterior pole (E-PP) were 55.1, 4.03 and 2.72 nM, respectively, at 0.25 or 0.50 h, with corresponding amfenac peak levels of 41.9, 3.10 and 0.705 nM at 1 or 4 h. By comparison, peak levels in sclera, choroid and retina sub-samples in a band between the ora serrata and the equator (OS-E) were 13- to 40-fold (nepafenac) or 11- to 23-fold (amfenac) higher, indicating an anterior-to-posterior directional concentration gradient. In multiple-dosed rabbit eyes, with 0.3% nepafenac instilled once-daily or 0.1% nepafenac instilled three-times daily, cumulative 24-h locally-distributed levels of nepafenac in E-PP retina were similar between these groups, whereas exposure to amfenac once-daily dosing nepafenac 0.3% was 51% of that achieved with three-times daily dosing of 0.1%. In single-dosed monkey eyes, concentration gradients showed similar directionality as observed in rabbit eyes. Peak concentrations of locally-distributed nepafenac were 1580, 386, 292 and 13.8 nM in E-PP sclera, choroid and retina, vitreous humor, respectively, at 1 or 2 h after drug instillation. Corresponding amfenac concentrations were 21.3, 11.8, 2.58 and 2.82 nM, observed 1 or 2 h post-instillation. The data indicate that topically administered nepafenac and its metabolite amfenac reach pharmacologically relevant concentrations in the posterior eye segment (choroid and retina) via local distribution, following an anterior-to-posterior concentration gradient. The proposed pathway involves a choroidal/suprachoroidal or periocular route, along with an inward movement of drug through the sclera, choroid and retina, with negligible vitreal compartment involvement. Sustained high nepafenac concentrations in posterior segment tissues may be a reservoir for hydrolysis to amfenac.

Comparison of human tracheal/bronchial epithelial cell culture and bovine nasal respiratory explants for nasal drug transport studies.

Ten drug compounds with varying physicochemical properties and transporter substrate specificities were investigated to compare their in vitro permeabilities across bovine nasal respiratory explants and the EpiAirway system, both established models for the assessment of nasal drug absorption. Permeability across the bovine explants and EpiAirway correlated well with the partitioning behavior of compounds whose clogDC values were greater than 0. The permeabilities of all ten compounds were well-correlated between the two tissue models, with the permeability values through the EpiAirway tissues being approximately 10-fold higher than through the bovine explants due to the thickness differences between the models. For more lipophilic compounds, the in vitro permeabilities measured with both tissue systems were also predictive of the reported in vivo nasal bioavailabilities. Deviations from these correlations were observed for compounds reported to be substrates of p-glycoprotein or OCT transporters, and differences were also seen between the permeabilities measured in the tissue models for these compounds. Both models can be used to estimate the systemic bioavailability of moderately lipophilic compounds administered intranasally, while each may have particular advantages or disadvantages in estimating the bioavailability of drug compounds that are subject to local mucosal metabolism or to carrier-mediated uptake or efflux.