FIVE POSTERS, ONE EXHIBITOR-HOSTED SESSION—COME EXPLORE!

• 3850/D302: Lacrimal Gland Measurements in Most Common Preclinical Laboratory Animals, presented by Dr. Marianna Bacellar-Galdino, DVM, MSc, PhD, Veterinary Scientist, Ophthalmology
• 3865/D317: A Comparative Study of Ocular Anatomy in Three Different Laboratory Swine Strains, presented by Dr. Marianna Bacellar-Galdino, DVM, MSc, PhD, Veterinary Scientist, Ophthalmology
• 3868/D320: Comparison of Baseline Levels of Biomarkers Commonly Used to Assess Drug Candidate Safety, Efficacy, and Mechanism of Action in Cynomolgus Monkeys of Cambodian, Chinese, or Cambodian-Chinese Mixed Origin Bred in a U.S.-Based Research Facility, presented by Ashley Mahoney, MA, RLATG, Study Director, Senior Scientist
• 4054/G528: Toxicologic Profiles of Lipid Nanoparticle (LNP) Used as Delivery Systems for Nucleic Acid Therapeutics in Cynomolgus Monkeys: Insights From Cross-Study Analysis of Various LNP Formulations, presented by Yafei Chen, MS, Senior Research Fellow

March 25, 9:15 – 11:45 a.m.
 

• 4710/F501: Standardizing Immunomodulatory Dosing of Sirolimus in Nonhuman Primates for Gene Therapy: A Data-Driven Review, presented by Julie Forget, DESS Tox, DABT, Senior Director, Safety Assessment.
   

Dr. Norbert Makori, Vice President of Toxicology, will present on the biological similarity assessed among cynomolgus monkeys of Cambodian, Chinese, and mixed origin.

This session is an Exhibitor-Hosted Session. Although not an official part of the SOT Annual Meeting scientific program, its presentation is permitted by the Society.

For over 30 years, Altasciences has taken a proactive, partner-driven approach to early drug development. By applying scientific insights at each development stage, we help sponsors make smarter, faster, and more informed decisions. 

Ready to move your drug development program forward with confidence?

Book time with one of our experts or visit us at Booth #1635, we want to connect and help you start your project on the right foot!

ABSTRACTS

Background and Purpose: The aim of this study was to localize and measure lacrimal glands (LG) from laboratory animals.
Methods: Both LGs were collected from Sprague Dawley (SD) rats (n=12), New Zealand White (NZW) rabbits (n=8), Beagle dogs (N=8), and Cynomolgus Macaques (CM) (n=20). LGs were dissected, weighed (mg), and measured (width x length in mm).
Results: Exorbital LG in SD rats was localized over the masseter muscle, with a mean weight of 117.4±3.1 mg, and measured 7.9 mm ±0.14 mm by12 mm ±0.31 mm. Intraorbital LG underneath the lower temporal part of the orbit, the mean weight was 13.5±1.9 mg, and measured 7.6 mm±0.27 mm by 3.3 mm ±0.06 mm. In NZW rabbits, the LG was embedded posteriorly in the superotemporal part of the orbit, the mean weight was 328.4±23 mg, and measured 8.4 mm ±0.17 mm by 20.2 mm ±0.09 mm. In Beagle dogs, the LG was in the superotemporal aspect of the globeand underneath the orbital ligament. The mean weight was 337.9±89.5 mg, and measured 11.1 mm ±0.16 mm by 4.59 mm ±0.23 mm. The LG in CM was located superotemporal aspect of the globe and was easily assessed by rotating the eye nasally and elevating the superior palpebra. The mean weight was 50.4±2.6 mg and measured 11.73 mm ±0.41 mm by 4.25 ±0.12 mm.
Conclusions: LG location and measurements are essential information as new therapies and administration routes are being explored for the treatment of dry eye disease.

Background and Purpose: The use of laboratory swine in ophthalmic research has grown considerably due to their anatomical and physiological similarities to humans. This study was designed to confirm quantitatively the similarity of ocular structures, both in size and weight, between Sinclair Nanopigs® (SN), comparable to those of the well-established Göttingen Minipigs (GM) and Yucatan pigs (YP).
Methods: A total of 32 animals (15 SN, 12 GM, and 5 YP), with ages ranging from one to thirty-months old, were used in this study. Eyes were either dissected (24 SN eyes, 10 GM eyes, and 6 YP eyes) or fixed in 10% formaldehyde (6 SN eyes, 14 GM eyes, and 4 YP eyes) overnight for evaluation. Dissected eyes had the following tissues collected and weighed: aqueous and vitreous humor volumes, cornea, iris/ciliary body, lens, trabecular meshwork, retina, choroid/RPE, and sclera. Fixed eyes were sectioned sagittally for measurement of anteroposterior (axial) and transverse (horizontal) globe lengths, cornea diameter, anterior and posterior segment depths, and lens (thickness and diameter). All measurements were analyzed using ANOVA and the Tukey-Kramer Test.
Results: Within our preliminary results, no significant differences were observed in axial globe length, lens width/depth, and anterior segment depth between SN, GM, and YP. Although minimal, statistically significant differences were observed in transverse globe length (21.9 ± 2.22 mm SN, 20.3 ± 0.74 mm GM, 23.3 ± 0.82 mm YP), corneal diameter (13.0 ± 1.46 mm SN, 13.4 ± 0.67 mm GM, 15.3 ± 0.52 mm YP), and posterior segment depth (9.3 ± 0.82 mm SN, 10.5 ± 0.85 mm GM, 11.0 ± 0.82 mm YP).
Conclusions: In conclusion, while statistically significant differences were observed in some globe measurements among all 3 species, eyes from all 3 species are comparable in weight and size and equally suitable for use in ocular studies.
Sinclair Nanopig® eyes are comparable in size and weight to Göttingen and Yucatan minipigs, making all three suitable for ocular research.

Cynomolgus monkeys (Macaca fascicularis) are a commonly used nonhuman primate model in preclinical toxicology research. Preclinical drug programs predominantly utilize cynomolgus monkeys of a single origin (Southeast Asian or Mauritian) to reduce experimental variability; however, a restriction in origin poses supply challenges. Here, we explore the use of mixed origin cynomolgus monkeys born at a US breeding facility by (1) characterizing standard biomarkers used to evaluate drug candidates’ effects (clinical pathology, peripheral blood lymphocytes [by immunophenotyping], complement protein fragments, and cytokines) in Cambodian-Chinese cynomolgus monkeys, and (2) comparing the biomarkers to cynomolgus monkeys of Cambodian alone or Chinese alone origin. A total of thirty, research naïve, juvenile cynomolgus monkeys (n=10 per origin) were sampled. Clinical pathology parameters were quantified using standard diagnostic equipment, and peripheral blood lymphocytes, complement protein fragments, and cytokine levels were quantified using immunoassays. Preliminary data suggest that there are no significant differences in baseline levels of biomarkers between cynomolgus monkeys of Cambodian, Chinese, or Cambodian-Chinese mixed origin bred in a US-based Research Facility. These findings are important because they support the use of mixed-origin cynomolgus monkeys born at a US breeding facility in preclinical toxicology research.

Background and Purpose: Lipid nanoparticles (LNPs) are widely used as delivery vehicles for nucleic acid therapeutics. While extensive research has addressed LNP-mRNA vaccine safety in clinical settings, LNP-only toxicological responses remain insufficiently characterized (in preclinical evaluations) in nonhuman primates (NHPs). The review by Wang et al. (2024, Vaccines) summarized that LNP toxicity involves several mechanisms, including inflammation, immune responses, and off-target accumulation in organs such as the liver, lungs, and spleen, and highlighted the lack of LNP-specific human and NHP data. To address this translational gap, we conducted a cross-study characterization of empty LNP-induced toxicity in cynomolgus monkeys to establish a nonclinical vehicle baseline to compare with LNP-encapsulated nucleic acid products.
Methods: We utilized Certara’s SEND Explorer (Warehouse version) to integrate multiple LNP preclinical studies (2022-2025) into a cross-study toxicity profile, which enabled the detection of reproducible organ/system findings, quantification of incidence/severity trends, and data-driven ranking of LNP reactogenicity. Data was obtained from >20 single- and repeat-dose toxicity studies involving empty LNP formulations and selected representative formulations differing in ionizable lipid chemistry and dosing regimen (up to 8 mg/kg; IV or IM). 
Clinical pathology data consisting of hematology and serum chemistry results (including acute-phase proteins: C-reactive protein [CRP], fibrinogen, and albumin) were reviewed in conjunction with microscopic findings across major organs (liver, spleen, lymphoid tissues, and bone marrow). Clinical and macroscopic observations were also reviewed. 
Results: Transient and reversible pronounced increases in liver transaminase activities (i.e., ALT, AST) and acute phase protein concentrations (e.g., CRP) were observed approximately 2 to 5 days post-administration across these studies. Notable microscopic findings included single-cell necrosis of the hepatocytes, inflammatory cell infiltration, hypertrophy of the hepatocytes and Kupffer cells in the liver, and extramedullary hematopoiesis in the spleen and lymph nodes. Similar results were discovered in repeated toxicity studies of patisiran (siRNA-LNP); single-cell necrosis of hepatocytes was commonly observed with associated hepatic enzyme increase, and this toxicity was considered to be caused by LNP itself rather than mRNA-LNP (EMA/CHMP Assessment Report, 2018). In some of the investigative studies, necropsies were performed more than a week after administration, which may indicate that hepatocellular injury (accompanied by elevated liver enzymes) that occurred a few days after administration was in the process of recovery or had resolved at the time of necropsy. The clinical observations remained unremarkable. These reproducible patterns align with mechanistic evidence from the literature (Wang et al., 2024), showing that ionizable lipids may activate and further induce hepatic and/or immune responses.
Conclusions: These findings establish a vehicle-specific baseline that distinguishes payload-independent effects and supports standardization of nonclinical LNP safety evaluation through historical-control integration. This dataset provides a foundation for future benchmarking of LNP-based therapeutics.

Background and Purpose: Gene therapy continues to progress as a viable therapeutic intervention for genetic disorders. These therapeutic interventions often use viral vectors (eg, adeno-associated virus) and lipid nanoparticles as a platform, which may elicit severe immunogenic responses. Immunomodulatory agents such as Sirolimus, an mTOR inhibitor, improve tolerability due to the immunosuppressive effects, including modulation of T-cell activity and reduction of inflammatory responses. In clinical practice, recommended human dosages of Sirolimus vary based on indication, body weight, and immunologic risk, with target trough blood concentrations generally ranging from 5 to 15 ng/mL. The purpose of this abstract is to establish a nonclinical reference range for Sirolimus dosing in mg/kg to facilitate therapeutic dose calculations (ease of study conduct and improve reproducibility in nonclinical studies) in nonhuman primates. 
Methods: Across multiple safety assessment studies conducted over the past two years, a total of 35 cynomolgus monkeys were identified as receiving Sirolimus treatment, either as a monotherapy or in combination with other immunosuppressive agents, as part of the study design, involving either once- or twice-daily administration, with or without weekly dose adjustments. Of these, 21 animals were selected for evaluation of the target dose level vs corresponding blood concentrations. Whole blood samples were collected weekly, using K2EDTA tubes, and Sirolimus concentrations were quantified via high-performance liquid chromatography with tandem mass spectrometry (LC-MS/MS). For each animal, the Sirolimus dose was calculated based on initial level (mg/m²), most recent body weight, and body surface area (BSA) conversion methodology. This value was then converted into a practical dosing unit of mg/kg.
Results: Sirolimus treatment typically began 2 to 3 days prior to the gene therapy administration and continued daily for a duration ranging from 5 days to 2 months following the gene therapy dose. In general, incremental increases in mg/kg dosing were associated with higher trough and peak Sirolimus blood concentrations; however, individual animal responses varied considerably throughout the study periods.
A review of non-clinical gene therapy study designs indicated an intended target therapeutic blood concentration between 2 and 10 ng/mL per day. Measured blood concentrations across studies ranged from 1.2 to 8.5 ng/mL, with corresponding calculated dose levels between 0.15 and 0.57 mg/kg/day. Notably, inter-animal variability was observed even at similar levels. Additionally, dose adjustments generally resulted in changes to blood concentrations within ±10% of prior levels. Based on the cumulative data review, a Sirolimus dose range of 0.2 to 0.5 mg/kg/day is proposed to achieve the intended target therapeutic trough blood levels.
Conclusions: Sirolimus dosing regimens in nonhuman primate gene therapy studies varied in schedule and duration, with some adjustments along the way requiring blood sample collection to confirm blood concentration levels. While higher mg/kg doses generally led to increased blood concentrations, individual animal variability was significant. The proposed dose range of 0.2 to 0.5 mg/kg/day establishes a foundational framework for achieving therapeutic Sirolimus levels in nonhuman primates, reduces the frequency of blood collections required for monitoring, while also enabling more consistent comparisons across nonclinical studies.

Session Description: Clinical pathology measures, lymphocyte immunophenotypes, complement fragments, and cytokines were compared among cynomolgus monkeys of Cambodian, Chinese, and mixed origin to assess biological similarity. Particular focus was placed on offspring from Cambodian × Chinese pairings to determine whether mixed origin breeding produces immunological and biochemical profiles consistent with single origin animals.

This session is an Exhibitor-Hosted Session. Although not an official part of the SOT Annual Meeting scientific program, its presentation is permitted by the Society.