Single-dose Toxicity Study Research Articles

Roflumilast-loaded nanostructured lipid carriers attenuate oxidative stress and neuroinflammation in Parkinson’s disease model

Parkinson’s disease (PD) is a progressive neurodegenerative disorder with limited symptomatic treatment options. Targeting phosphodiesterase 4 (PDE4) has shown a promising result in several preclinical studies. In our study, we aim to repurpose US FDA-approved PDE4 inhibitor for PD. Through in-silico study, we identified roflumilast (ROF) as the potential candidate targeting PDE4B2. In Drosophila PD expressing the A30P mutant α-synuclein model, ROF exhibited anti-PD effects as indicated by negative geotaxis and antioxidant activities. Given the low brain distribution of ROF (<50%) at clinical doses, incorporation into nanostructured lipid carriers (NLCs) was carried out to enhanced blood-brain barrier permeability. In vitro release studies indicated sustained ROF release from NLCs (≈75%) over 24 h. Single-dose oral toxicity studies reported no mortality or toxicity signs. ROF-loaded NLCs significantly alleviated behavioural deficits, increased antioxidant parameters (p < 0.05), and reduced TNF-α and IL-6 levels (p < 0.5) in the striatum compared to pure ROF. ROF-loaded NLCs demonstrated potential anti-PD effects with high efficacy than pure ROF. Our study suggests that nanostructured lipid carriers (NLCs) can be a promising drug delivery system to overcome limitations associated with poor brain bioavailability of lipophilic drugs like ROF for PD treatment. Further investigation related to brain occupancy and underlying mechanisms of our formulation is warranted to confirm and strengthen our current findings.

Advancing 6-bromo-7-[11C]methylpurine to clinical use: improved regioselective radiosynthesis, non-clinical toxicity data and human dosimetry estimates

Background6-Bromo-7-[11C]methylpurine ([11C]BMP) is a radiotracer for positron emission tomography (PET) to measure multidrug resistance-associated protein 1 (MRP1) transport activity in different tissues. Previously reported radiosyntheses of [11C]BMP afforded a mixture of 7- and 9-[11C]methyl regioisomers. To prepare for clinical use, we here report an improved regioselective radiosynthesis of [11C]BMP, the results of a non-clinical toxicity study as well as human dosimetry estimates based on mouse PET data.Results[11C]BMP was synthesised by regioselective N7-methylation of 6-bromo-7H-purine (prepared under good manufacturing practice) with [11C]methyl triflate in presence of 2,2,6,6-tetramethylpiperidine magnesium chloride in a TRACERlab™ FX2 C synthesis module. [11C]BMP was obtained within a total synthesis time of approximately 43 min in a decay-corrected radiochemical yield of 20.5 ± 5.2%, based on starting [11C]methyl iodide, with a radiochemical purity > 99% and a molar activity at end of synthesis of 197 ± 130 GBq/μmol (n = 28). An extended single-dose toxicity study conducted in male and female Wistar rats under good laboratory practice after single intravenous (i.v.) administration of unlabelled BMP (2 mg/kg body weight) revealed no test item related adverse effects. Human dosimetry estimates, based on dynamic whole-body PET data in female C57BL/6J mice, suggested that an i.v. injected activity amount of 400 MBq of [11C]BMP will deliver an effective dose in the typical range of 11C-labelled radiotracers.Conclusions[11C]BMP can be produced in sufficient amounts and acceptable quality for clinical use. Data from the non-clinical safety evaluation showed no adverse effects and suggested that the administration of [11C]BMP will be safe and well tolerated in humans.

Evaluating the toxicity of the roots of Asarum heterotropoides var. mandshuricum extracted using the decoction method: Genotoxicity, single-dose toxicity, and 13-week repeated-dose toxicity studies

Ethnopharmacological relevanceThe roots of Asarum heterotropoides F. Maekawa var. mandshuricum F. Maekawa (AR) is a traditional herbal medicine used across Asia, including Korea, China, and Japan. AR exhibits a range of biological activities, such as anti-inflammatory, anti-cancer, cold treatment, and anti-nociceptive effects. Various extraction methods, including decoction, which utilizes traditional knowledge and techniques. The AR decoction extract expected to contain fewer toxicants and have reduced toxicity due to the use of hot water in the extraction process. However, scientific evidence on the toxicity of AR decoction extracts is lacking, necessitating further studies for safe usage. Aim of the studyThis study aimed to evaluate the genotoxicity and toxicity of single and repeated administration of AR decoction extracts. Materials and methodsThe genotoxicity was assessed using a bacterial reverse mutation (Ames test), an in vitro mammalian chromosome aberration test (CA test), and an in vivo micronucleus test (MN test) in Sprague-Dawley (SD) rats. The general toxicity was evaluated through single-dose and 13-week repeated-dose toxicity studies. In the single-dose toxicity study, 40 SD rats were orally administered AR decoction extract at doses of 1000, 2000, and 5000 mg/kg. In the 13-week repeated-dose toxicity study, 140 SD rats received daily oral doses of 0, 250, 500, 1000, 2000, and 5000 mg/kg of AR decoction extract. ResultsThe genotoxicity tests revealed that AR decoction extract was not genotoxic. The single-dose toxicity study showed no changes in body weight, clinical pathology, or macroscopic findings, with the approximate lethal dose (ALD) exceeding 5000 mg/kg. The 13-week repeated-dose toxicity study demonstrated no treatment-related changes in body weight, general symptoms, hematology, clinical chemistry, or urinalysis. Histopathological findings revealed hyperplasia of squamous cells in the forestomach after AR decoction extract administration, a treatment-related effect that resolved during the recovery period. The no observed adverse effect level (NOAEL) for both male and female rats was estimated to be 2000 mg/kg. ConclusionsThis study establishes the non-toxic dose of AR decoction extract, providing a foundation for further non-clinical and clinical evaluations AR safety.

Single and repeat-dose toxicity and local tolerance assessment of newly developed oil emulsion adjuvant formulations for veterinary purposes

Adjuvants are components of vaccines that boost the intensity, duration, and breadth of the immune response. Insight into the mechanisms responsible for the immunotoxicity of both local and systemic adverse reactions following the use of adjuvants has been gained through research over the past twenty years. In the present study, single and repeated-dose toxicity and local tolerance of newly developed Water-in-Oil (W/O) and Water-in-Oil-in-Water (W/O/W) Emulsion adjuvants (Coralvac RZ 528, Coralvac RZ 506, Coralvac AT 318, Coralvac AT 318 SIS and Coralvac 252) by Coral Biotechnology Industry and Trade Incorporated Company were demonstrated after intramuscular injection in mice. In both toxicity studies, no adverse reactions such as death, general appearance, behavior, or weight loss were observed in the mice in the experimental groups. The results indicate that clinical chemistry parameters demonstrated normal function of the major organs and no irreversible damage to the mice in all adjuvant groups compared to the control group. In histopathologic investigation of single dose toxicity study, inflammation, edema, and large amounts of lipid droplets were observed on the 7th day in all experimental groups. On the 14th day, when the control group and the experimental groups were compared, it was seen that inflammation and edema had decreased considerably. Similarly, repeated dose toxicity study showed mild inflammation and edema in the control group, while quite widespread and severe inflammation, edema, and diffuse lipid droplets of varying sizes were observed in all adjuvant groups compared to the control group. These observations would be useful for the future development of oil-based adjuvants and their use in veterinary inactive vaccines.

RBD5044 - a novel anti-ApoC3 GalNAc-siRNA drug resulted in sustained and profound reduction of triglycerides in mice and Rhesus monkeys

Abstract Introduction Hypertriglyceridemia leads to endothelial dysfunction and contributes to the onset and progression of atherosclerosis as well as an increased risk of acute pancreatitis. Inhibition of Apolipoprotein-CIII (APOC3) via the RNA interference mechanism is supposed to reduce plasma Triglycerides (TG) levels with durable and high efficacy. RBD5044, which targets APOC3 mRNA in the liver, is a chemically-modified double-stranded small interfering RNA (siRNA) conjugated with N-acetylgalactosamine (Ribo-GalSTAR). Purpose To investigate the preclinical efficacy and safety profile of RBD5044. Methods Rhesus monkeys with spontaneously developed hypertriglyceridemia were given a single subcutaneous (sc) injection of RBD5044. Humanized APOC3 transgenic mice were treated with a single dose or repeated doses (once every two weeks for three doses, Q2W×3) of RBD5044. Plasma was collected to quantify APOC3 and lipid biomarkers to evaluate preclinical efficacy of RBD5044. SD rats and cynomolgus monkeys were used to evaluate the preclinical toxicology for subcutaneously injected RBD5044, including single-dose toxicity studies and 4-week repeat-dose pivotal toxicology studies. Results In the rhesus monkeys with spontaneous hypertriglyceridemia, the maximum level of inhibition reached 61.2 % in APOC3 and resulted in a TG reduction by 53.3%. The levels of both APOC3 and TG were recovered to baseline till Day 85 after a single dose of 3 mg/kg RBD5044. In humanized APOC3 transgenic mice, RBD5044 achieved an average maximum inhibition level of over 90% for APOC3 and around 90% for TG after both single and repeated doses. The APOC3 and TG levels were recovered on Day 63 after a single dose of 3 mg/kg. On Day 63 after the last repeated dose at 3 mg/kg, the inhibition level remained at 41.6% for APOC3 and 49.4% for TG, hence did not recover to baseline within the study period. RBD5044 also showed reductions in total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels and elevations in high-density lipoprotein cholesterol (HDL-C) levels. Toxicology studies showed there is a sufficient therapeutic margin that supports the clinical development of RBD5044 with NOAEL of 40 mg/kg in rats and 300 mg/kg in monkeys. Conclusions RBD5044 shows high efficacy, long duration and a good safety profile in preclinical studies. The Phase I trial of RBD5044 injection in healthy volunteers has been initiated in Australia.Figure 1Figure 2

Assessment of Safety Profile of Activated Curcumin C3 Complex (AC3®), Enriched Extract of Bisdemethoxycurcumin from the Rhizomes of Curcuma longa.

The present work was carried out to investigate the toxic effects of Activated Curcumin C3 Complex (AC3®) through the methods of acute, subacute, subchronic, reproductive/developmental toxicity, and genotoxicity when administered orally in experimental rodents. The studies were carried out in line with OECD principles of good laboratory practice. A single-dose acute oral toxicity study was conducted on female Wistar rats that produced no toxic effects after 14 days (the observation period) of treatment. Subacute, subchronic, and reproductive/developmental studies were conducted in Wistar rats, divided equally into vehicle control, 125, 250, and 500 mg/kg dose groups along with recovery groups for vehicle control and high dose. In all the studies, there were no abnormal clinical signs/behavioral changes, reproductive and developmental parameters, or gross and histopathological changes. Likewise, no alteration was found in the body weight, hematology, and other biochemical parameters. Also, it did not show mutagenicity in the in vitro AMES test or clastogenicity and aneugenicity in the in vivo micronucleus test, indicating that AC3® did not induce any genotoxic effects. This revealed that oral administration of AC3® is safe in rodents, nonmutagenic, and had no observed adverse effects under experimental conditions.

Safety Study of an Original Mesenchymal Stromal Cell Secretome-Based Medicinal Product for Spermatogenesis Restoration

SCIENTIFIC RELEVANCE. Currently, there are no effective and safe medicinal products for idiopathic male infertility. Previous studies in two animal models of infertility (short-term cryptorchidism in rats and doxorubicin-induced testicular injury in mice) have shown the effectiveness of an originator medicinal product based on the mesenchymal stromal cell (MSC) secretome.AIM. The aim of the study was to evaluate the toxicity profile of the MSC secretome-based medicinal product in rats after local intratesticular or intramuscular administration.MATERIALS AND METHODS. The MSC secretome is a combination of factors secreted by MSCs in low-glucose Dulbecco’s modified Eagle’s medium (DMEM-LG) for MSC conditioning. In the single-dose toxicity study, the MSC secretome-based medicinal product was injected under the testicular tunica albuginea of male Wistar rats (15 per group) at doses of 15 and 25 relative units (RU) per animal, which are 1.5 and 2.5 times higher than the therapeutic dose (10 RU). In the repeat-dose toxicity study, male Wistar rats (10 per group) received intramuscular thigh injections of the medicinal product on days 1, 6, and 12 at doses of 15 and 25 RU per animal. The local tolerance study involved histopathological examination of the testes and thighs at the injection site. All studies included control groups of intact animals and animals similarly injected with blank DMEM-LG. The early follow-up period was 14 days, and the late follow-up period was 42 days.RESULTS. The rats showed no changes in the general condition after single and repeated doses of the MSC secretome-based medicinal product. Single subtunical doses induced moderate irritation; its signs included pathological changes in individual seminiferous tubules: epithelial atrophy (70% of the animals on day 14; 55% at late follow-up) and sperm stasis (70% of the animals). Similar changes were observed in the blank DMEM-LG group (up to 80% of the animals). There were no pathological changes in the tissues after repeated injections. A transient increase in alkaline phosphatase activity was detected in animals after their third intramuscular injection at a dose of 25 RU; the other biochemical parameters were normal in all study groups.CONCLUSIONS. The MSC secretome-based medicinal product has a favourable safety profile following both intratesticular and intramuscular administration, as it does not cause any permanent changes in the studied organs and tissues.

Supramolecular chemistry enables vat photopolymerization 3D printing of novel water-soluble tablets

Vat photopolymerization has garnered interest from pharmaceutical researchers for the fabrication of personalised medicines, especially for drugs that require high precision dosing or are heat labile. However, the 3D printed structures created thus far have been insoluble, limiting printable dosage forms to sustained-release systems or drug-eluting medical devices which do not require dissolution of the printed matrix. Resins that produce water-soluble structures will enable more versatile drug release profiles and expand potential applications. To achieve this, instead of employing cross-linking chemistry to fabricate matrices, supramolecular chemistry may be used to impart dynamic interaction between polymer chains. In this study, water-soluble drug-loaded printlets (3D printed tablets) are fabricated via digital light processing (DLP) 3DP for the first time. Six formulations with varying ratios of an electrolyte acrylate monomer, [2-(acryloyloxy)ethyl]trimethylammonium chloride (TMAEA), and a co-monomer, 1-vinyl-2-pyrrolidone (NVP), were prepared to produce paracetamol-loaded printlets. 1H NMR spectroscopy analysis confirmed the integration of TMAEA and NVP in the polymer, and residual TMAEA monomers were found to be present only in trace amounts (0.71 – 1.37 %w/w). The apparent molecular mass of the photopolymerised polymer was found to exceed 300,000 Da with hydrodynamic radii of 15 – 20 nm, estimated based on 1H DOSY NMR measurements The loaded paracetamol was completely released from the printlets between 45 minutes to 5 hours. In vivo single-dose acute toxicity studies in rats suggest that the printlets did not cause any tissue damage. The findings reported in this study represent a significant step towards the adoption of vat photopolymerization-based 3DP to produce personalised medicines.

CD19 chimeric antigen receptor T cell therapy in leukemia xenograft mouse: Anti-leukemic efficacy, kinetics, and 4-week single-dose toxicity

CD19 Chimeric antigen receptor T (CAR-T) cell therapy has shown a promising response rate for relapsed/refractory B-cell malignancies. However, serious side effects such as cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome arose in early case reports. Though several preclinical and clinical studies of CAR-T cell therapy have been reported, there is a lack of toxicological assessments. This study was carried out as a preclinical assessment of CD19 CAR-T cell therapy, including the anti-leukemic efficacy, kinetics in peripheral blood, and 4-week single-dose toxicity evaluation in leukemia xenograft mice. Leukemia xenograft mice model was established by injecting 1.0 × 105 cells/mouse of luciferase-labeled human B cell acute lymphoblastic leukemia (B-ALL) cell line via the tail vein, and after 3 days, 2.0 or 4.0 × 106 cells/mouse of CD19 CAR-T cells were injected intravenously. CD19 CAR-T cells showed significant anti-leukemic efficacy, showing inhibition of tumor progression in the bioluminescence-based in-vivo imaging system. In the kinetics study using qPCR, CAR-T cells peaked in peripheral blood on day 60 in males and day 30 in females. In a 4-week single-dose toxicity study, CD19 CAR-T cell injected groups showed no mortality and toxicological signs, or changes in body weight, food/water consumption, hematology, clinical chemistry, organ weights, and histopathology compared to control groups. These results suggested that 4.0 × 106 cells/mouse of CD19 CAR-T cells were effective in B-ALL xenograft mice without serious side effects, so the no-observed adverse effect level (NOAEL) was estimated to be higher than 4.0 × 106 cells/mouse, under the condition examined in the current study.

Toxicological safety assessment of AP-Bio®, a standardized extract of Andrographis paniculata in Sprague Dawley rats.

Andrographis paniculata, commonly known as green chiretta, is a traditionally used plant in India, China, and Southeast Asian countries for its varied health benefits including immune health. The objective of the present study was to assess the safety of AP-Bio®, a standardized A. paniculata extract in Sprague Dawley rats by following the Organisation for Economic Cooperation and Development (OECD) test guidelines of acute and 90-day repeated dose sub-chronic toxicity studies. AP-Bio® did not show any treatment-related clinical signs of toxicity or mortality during the 14-day observation period in animals tested in the single-dose acute oral toxicity study up to a dose of 5000 mg/kg body weight. In the 90-day repeated dose sub-chronic oral toxicity study, no treatment-related adverse clinical signs were observed in any of the treated groups (300, 600, and 900 mg/kg). All treated animals showed usual weight gain and comparable feed intake. The ophthalmoscope examination did not reveal any abnormalities. Also, no toxicologically significant changes were observed in urinalysis, hematology, and blood chemistry parameters. Absolute organ weights and relative organ weights of vital organs did not differ significantly compared to control. Gross and histopathological findings did not show any remarkable and treatment-related changes. Results of the safety evaluation showed the median lethal dose (LD50 ) of AP-Bio® was found to be more than 5000 mg/kg rat body weight and the no observed adverse effect level (NOAEL) of AP-Bio® was found to be 900 mg/kg rat body weight.

Non-clinical pharmacology and toxicology studies of LPM6690061, a novel 5-hydroxytryptamine (5-HT)2A receptor inverse agonist.

LPM6690061 is a novel compound with 5-HT2A receptor antagonist and inverse agonist activities. To support the clinical trial and marketing application of LPM6690061, a series of pharmacology and toxicology studies have been conducted. In vitro and in vivo pharmacology studies showed that LPM6690061 had high inverse agonism and antagonism activities against human 5-HT2A receptors, and demonstrated significant antipsychotic-like effects in two rat models: the DOI-induced head-twitch model and the MK-801-induced hyperactivity model, which was more effective than the control drug pimavanserin. LPM6690061 did not have detectable side effects on the neurobehavioral activities and respiratory function in rats, or on the ECG or blood pressure in dogs at the doses of 2 and 6mg/kg. The half maximal inhibitory concentration (IC50) of LPM6690061 for inhibiting hERG current was 1.02μM. Three in vivo toxicology studies were conducted. In the single dose toxicity study in rats and dogs, the maximum tolerated dose of LPM6690061 was 100mg/kg. In the 4-week repeat dose toxicity study in rats, the main detectable toxic reactions of LPM6690061 included moderate artery wall hypertrophy, minimal to mild mixed cell inflammation and increased macrophages in the lung, which generally recovered after a 4-week drug withdrawal period. In the 4-week repeat dose toxicity study in dogs, no detectable toxicity was observed. The doses of no-observed-adverse-effect-level (NOAEL) in rats and dogs were 10mg/kg and 20mg/kg, respectively. In conclusion, both in vitro and in vivo pharmacological and toxicological studies showed that LPM6690061 was a safe and efficacious 5-HT2A receptor antagonist/inverse agonist which supports the clinical development as a novel antipsychotic drug.

Cypermethrin Toxicity-induced Infertility: An Assessment of Longitudinal Transfer of Protective Potentials of Date Fruit Extracts in Wister Rats.

There is a potential for longitudinal and horizontal transfer of the cytotoxic effects of cypermethrin, and evidence suggests that date fruit extracts can ameliorate these cytotoxic effects. Thus, the current study evaluated female Wister rats' fertility and pup parameters after mating males treated with cypermethrin and date fruit (Phoenix dactylifera) extract. Adult Wistar rats (n = 74; 140 - 207 g) were used to conduct this experiment in two phases: The first phase was a single dose toxicity study (n = 18), while the second phase (n = 56) evaluated female Wister rats' reproductive and pup development parameters after mating with male Wistar rats exposed to date fruit extract and cypermethrin. Male rats were distributed randomly into four groups (n = 7 per group) and administered distilled water (Group I); 60 mg/kg cypermethrin (Group II) to simulate infertility; 250 mg/kg date fruit extract alone (Group III); and date fruit extracts plus 60 mg/kg cypermethrin (Group IV). Treated males were then mated with healthy female rats at a ratio of 1:1. Successfully mated females were appraised for conception and pregnancy rates, gestation length, litter size, and weights at birth, and on days 5, 10, 15, and 21 post-partum, an anogenital distance at day-20, sex ratio, and age of pup when hair growth was evident. Significant differences (p < 0.05) were observed in litter size and male anogenital distance but not in reproductive performance. Also, the study demonstrated that date fruit extract skewed the sex ratio of offspring to more female than male pups when female Wister rats were mated with males that received date fruit extracts alone or cypermethrin and date fruit extracts. The body weight gain did not differ significantly between the control and cypermethrin-treated groups. This evidence suggested a longitudinal transfer of the protective effects of date fruit extracts following a weekly exposure of male rats to cypermethrin at 60 mg/kg.

Evaluation of the Antiviral Efficacy of Subcutaneous Nafamostat Formulated with Glycyrrhizic Acid against SARS-CoV-2 in a Murine Model.

The ongoing COVID-19 pandemic highlights the urgent need for effective antiviral agents and vaccines. Drug repositioning, which involves modifying existing drugs, offers a promising approach for expediting the development of novel therapeutics. In this study, we developed a new drug, MDB-MDB-601a-NM, by modifying the existing drug nafamostat (NM) with the incorporation of glycyrrhizic acid (GA). We assessed the pharmacokinetic profiles of MDB-601a-NM and nafamostat in Sprague-Dawley rats, revealing rapid clearance of nafamostat and sustained drug concentration of MDB-601a-NM after subcutaneous administration. Single-dose toxicity studies showed potential toxicity and persistent swelling at the injection site with high-dose administration of MDB-601a-NM. Furthermore, we evaluated the efficacy of MDB-601a-NM in protecting against SARS-CoV-2 infection using the K18 hACE-2 transgenic mouse model. Mice treated with 60 mg/kg and 100 mg/kg of MDB-601a-NM exhibited improved protectivity in terms of weight loss and survival rates compared to the nafamostat-treated group. Histopathological analysis revealed dose-dependent improvements in histopathological changes and enhanced inhibitory efficacy in MDB-601a-NM-treated groups. Notably, no viral replication was detected in the brain tissue when mice were treated with 60 mg/kg and 100 mg/kg of MDB-601a-NM. Our developed MDB-601a-NM, a modified Nafamostat with glycyrrhizic acid, shows improved protectivity against SARS-CoV-2 infection. Its sustained drug concentration after subcutaneous administration and dose-dependent improvements makes it a promising therapeutic option.

Virtual Screening of Nrf2 Dietary-Derived Agonists and Safety by a New Deep-Learning Model and Verified In Vitro and In Vivo.

Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is an essential regulatory target of antioxidants, but the lack of Nrf2 active site information has hindered discovery of new Nrf2 agonists from food-derived compounds by large-scale virtual screening. Two deep-learning models were separately trained to screen for Nrf2-agonists and safety. The trained models screened potentially active chemicals from approximately 70,000 dietary compounds within 5 min. Of the 169 potential Nrf2 agonists identified via deep-learning screening, 137 had not been reported before. Six compounds selected from the new Nrf2 agonists significantly increased (p < 0.05) the activity of Nrf2 on carbon tetrachloride (CCl4)-intoxicated HepG2 cells (nicotiflorin (99.44 ± 18.5%), artemetin (97.91 ± 8.22%), daidzin (87.73 ± 3.77%), linonin (74.27 ± 5.73%), sinensetin (72.74 ± 10.41%), and tectoridin (77.78 ± 4.80%)), and their safety were demonstrated by an MTT assay. The safety and Nrf2 agonistic activity of nicotiflorin, artemetin, and daidzin were also reconfirm by a single-dose acute oral toxicity study and CCl4-intoxicated rat assay.

Abstract 2648: In vivo efficacy and preclinical safety profile of NN3201, an anti-cKIT antibody-drug conjugate, for treating SCLC and AML

Abstract Overexpression and activating mutations of cKIT are associated with tumor aggressiveness and poor prognosis in various cancer patients such as small cell lung cancer (SCLC), gastrointestinal stromal tumor (GIST), acute myeloid leukemia (AML), and mastocytoma. Since small molecule inhibitors including imatinib frequently have a limited therapeutic application due to eventual drug resistance and severe adverse events, we developed the cKIT-directed antibody-drug conjugate (ADC), NN3201, for the treatment of wild-type and mutant cKIT-positive cancers. NN3201 is an ADC conjugate of the antimitotic payload MMAE to the fully human 2G4 antibody, directed against cKIT, via the cysteine re-bridging technology ThioBridge® at a drug-to-antibody ratio (DAR) of 4. NN3201 displayed preferable biophysical properties and broadly potent in vitro antitumor activities across various cKIT-positive tumor cell lines. NN3201 exhibited potent in vivo antitumor activities in cKIT-positive tumor cell line xenograft and patient-derived tumor xenograft models of SCLC and AML, representing robust and durable antitumor responses. Furthermore, in a single-dose toxicity study with cynomolgus monkey, no significant or severe clinical toxicity signs were observed in animals dosed at 1, 2, and 3 mg/kg. Even though a decrease in reticulocyte, red cell mass (hemoglobin and red blood cell), neutrophil, and monocyte counts, along with bone marrow recovery and reticulocyte compensatory mechanism, red blood cell and white blood cell recovery were observed from day 14 in the low and medium dose groups and day 21 in the high dose group, dose-dependently. These preclinical results suggest that NN3201 is a potential therapeutic agent for the treatment of cKIT-positive cancers and support the further clinical evaluation in SCLC and AML. Citation Format: Han-Jik Ko, Sung Tae Kim, Jin Gu Cho, Jin-Ock Kim, Jung Tae Lee, Sang Gyu Park. In vivo efficacy and preclinical safety profile of NN3201, an anti-cKIT antibody-drug conjugate, for treating SCLC and AML [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2648.

Abstract 438: Antibody drug conjugate using a novel anti-CDCP1 antibody with low hematopoietic stem-cell binding and rapid internalization showed high efficacy for solid cancer

Abstract CUB domain containing protein 1 (CDCP1) is a single transmembrane protein that is highly expressed in a broad range of solid cancers, including lung, breast, colorectal, pancreas, prostate, and ovarian cancers. Although no soluble ligand for CDCP1 is known, CDCP1 transduces signals resulting in cancer cell motility, epithelial mesenchymal transition, and metastasis by activating downstream signaling via homodimerization or heterodimerization with other cell surface molecules such as EGFR, HER2, and ITGB1. Owing to its important roles in cancer, CDCP1 has been reported as a promising therapeutic target for the treatment of solid cancers. While it is overexpressed in many of the abovementioned solid cancer types, several normal tissues such as esophagus, skin, and bone marrow hematopoietic stem cells (HSCs) also express CDCP1. To minimize the risk of toxicity, we generated novel anti-CDCP1 antibodies that bind weakly to bone marrow HSCs. Three isolated anti-CDCP1 monoclonal antibodies and their humanized versions showed weak binding to HSCs compared to other anti-CDCP1 antibodies reported from other groups. Although they only showed moderate binding activity to cancer cell lines, rapid internalization and efficient lysosomal trafficking was observed following CDCP1 binding. Subsequently, we generated antibody drug conjugates (ADCs) of the 3 anti-CDCP1 antibodies using PBD, MMAE, and MMAF as a cytotoxic payload with both a cleavable and non-cleavable linker. All constructed ADCs showed strong anti-tumor activity in multiple cancer cell lines in vitro. The cytotoxic activities of these ADCs were correlated to CDCP1 surface expression levels and internalization activity. The anti-CDCP1 ADCs showed strong anti-tumor efficacy in multiple cell line xenograft models. We selected the clone h14A043 for further evaluation owing to its observed potent anti-tumor activity both in vitro and in vivo. We then constructed h14A043-ATAC (Antibody Targeted Amanitin Conjugate), which has a site-specifically conjugated amanitin derivative with DAR 2 and an Fc domain mutation that reduces the effector function of human IgG1. h14A043-ATAC showed good anti-tumor potency both in vitro and in vivo. In human prostate cancer PC3 cell line xenograft model, we observed significant tumor growth delay following treatment by h14A043-ATAC with a single administration of 0.1 mg/kg. Furthermore, we observed complete tumor remission in 3 out of 8 mice at 40 days after a single administration of 1 mg/kg. In the non-GLP single dose toxicity study using cynomolgus monkeys, h14A043-ATAC showed good serum stability and no hematological toxicity. Our results suggest that ADC using an anti-CDCP1 mAb with weak binding to bone marrow HSC and sufficient internalization activity could provide a new treatment option for refractory solid cancer patients. Citation Format: Shu-ichi Hashimoto, Shiori Miyamoyo, Aki Takaiwa, Koji Nakamura, Yukihito Tsukumo, Yoshinori Yamashita. Antibody drug conjugate using a novel anti-CDCP1 antibody with low hematopoietic stem-cell binding and rapid internalization showed high efficacy for solid cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 438.

Development of the 99mTc-Labelled SST2 Antagonist TECANT-1 for a First-in-Man Multicentre Clinical Study

Broad availability and cost-effectiveness of 99Mo/99mTc generators worldwide support the use, and thus the development, of novel 99mTc-labelled radiopharmaceuticals. In recent years, preclinical and clinical developments for neuroendocrine neoplasms patient management focused on somatostatin receptor subtype 2 (SST2) antagonists, mainly due to their superiority in SST2-tumour targeting and improved diagnostic sensitivity over agonists. The goal of this work was to provide a reliable method for facile preparation of a 99mTc-labelled SST2 antagonist, [99mTc]Tc-TECANT-1, in a hospital radiopharmacy setting, suitable for a multi-centre clinical trial. To ensure successful and reproducible on-site preparation of the radiopharmaceutical for human use shortly before administration, a freeze-dried three-vial kit was developed. The final composition of the kit was established based on the radiolabelling results obtained during the optimisation process, in which variables such as precursor content, pH and buffer, as well as kit formulations, were tested. Finally, the prepared GMP-grade batches met all predefined specification parameters together with long-term kit stability and stability of the product [99mTc]Tc-TECANT-1. Furthermore, the selected precursor content complies with micro-dosing, based on an extended single-dose toxicity study, where histopathology NOEL was established at 0.5 mg/kg BW, being more than 1000 times higher than the planned human dose of 20 µg. In conclusion, [99mTc]Tc-TECANT-1 is suitable to be advanced into a first-in-human clinical trial.

Development, Validation and Application of a Bridging ELISA for Detection of Antibodies against GQ1001 in Cynomolgus Monkey Serum.

Immunogenicity is a major issue associated with the PK, efficacy, and safety evaluation of therapeutic protein products during pre-clinical and clinical studies. A multi-tiered approach consisting of screening, confirmatory, and titration assays has been widely adopted for anti-drug antibody testing. GQ1001, a recombinant humanized anti-human epidermal growth factor receptor 2 monoclonal antibody covalently linked to a cytotoxin of DM1, possesses a novel format of antibody-drug conjugates. In this study, we reported the development, validation, and application of an acid-dissociation bridging enzyme-linked immunosorbent assay for the detection of antibodies against GQ1001 in cynomolgus monkey serum. The sensitivity of the screening assay was 126.141 ng/mL in undiluted serum. The screening assay and confirmatory assay were neither affected by the naïve monkey serum nor by 2% and 5% (v/v) erythrocyte hemolysates. Moreover, the assay was not subject to interference by 2500 ng/mL of human IgG1 in the samples. Drug interference at low positive control (150 ng/mL) and high positive control (8000 ng/mL) of anti-GQ1001 antibodies was not observed when GQ1001 concentrations were below 3.125 μg/mL and 100 μg/mL, respectively. Furthermore, no hook effect was observed for the positive antibodies in the concentration range of 8 to 64 μg/mL. The validated assay was, thereafter, successfully applied to a single-dose toxicity study of GQ1001. Anti-drug antibody positive rates among dosing animals and testing samples were reported, and no significant impact was found on toxicokinetic outcomes.

Phytochemical Screening, Toxic Effects, and Antimicrobial Activity Studies of Digitaria abyssinica (Hochst. ex A.Rich.) Stapf (Poaceae) Rhizome Extracts against Selected Uropathogenic Microorganisms.

In Kenya, the D. abyssinica rhizome's decoction is traditionally used to treat urinary tract infections (UTIs), mainly gonorrhea and candidiasis. UTIs are the most severe public health problems that affect over one hundred and fifty million people worldwide annually. They are caused by a wide range of microorganisms where Escherichia coli is known to be the main causative pathogen. Medicinal plants are used in traditional Kenya set up for treatment and most recently as an alternative source of treatment for UTIs due to the increased cost of treatment and many challenges experienced with antibiotic therapy. The current study is designed to investigate the phytochemical composition, acute oral toxicity, and antimicrobial activity of Digitaria abyssinica rhizome extracts against Staphylococcus aureus, Escherichia coli, Neisseria gonorrhea, and Candida albicans. The rhizomes of D. abyssinica were obtained, dried, ground, and extracted using water and organic solvents. The phytochemical assay was carried out using standard phytochemical screening methods. Single-dose toxicity studies were done to determine LD50 while disk diffusion and microbroth dilution techniques were used to determine antimicrobial activity. Results revealed that saponins, phenolics, alkaloids, cardiac glycosides, tannins, flavonoids, steroids, and terpenes were present in the powder, aqueous, methanol, and dichloromethane : methanol extracts. All the extracts had an LD50 of above 2,000 mg/kg of body weight and there was no observation of behavioral changes. Also, the aqueous and methanol extracts revealed antifungal activity against Candida albicans with the lowest average minimum zone of inhibition at MIC of 31.25 mg/ml. The study did not reveal antibacterial activity for any extract against the studied uropathogenic bacteria, Staphylococcus aureus, Escherichia coli, and Neisseria gonorrhoeae. The results from the current study suggested that D. abyssinica rhizome aqueous and methanol extracts have potential antifungal activity against C. albicans, thus validating the folklore of its use to treat candidiasis.

A novel drug-like water-soluble small molecule Focal Adhesion Kinase (FAK) activator promotes intestinal mucosal healing

Non-steroidal anti-inflammatory drugs (NSAIDs) injure the proximal and distal gut by different mechanisms. While many drugs reduce gastrointestinal injury, no drug directly stimulates mucosal wound healing. Focal adhesion kinase (FAK), a non-receptor tyrosine kinase, induces epithelial sheet migration.We synthesized and evaluated a water-soluble FAK-activating small molecule, M64HCl, with drug-like properties. Monolayer wound closure and Western blots measured migration and FAK phosphorylation in Caco-2 ​cells, in vitro kinase assays established FAK activation, and pharmacologic tests assessed drug-like properties. 30 ​mg/kg/day M64HCl was administered in two murine small intestine injury models for 4 days.M64HCl (0.1–1000 ​nM) dose-dependently increased Caco-2 FAK-Tyr 397 phosphorylation, without activating Pyk2 and accelerated Caco-2 monolayer wound closure. M64HCl dose-responsively activates the FAK kinase domain vs. the non-salt M64, increasing the Vmax of ATP-binding. Pharmacologic tests suggested M64HCl has drug-like properties and is enterally absorbed. M64HCl 25 ​mg/kg/day continuous infusion promoted healing of ischemic jejunal ulcers and indomethacin-induced small intestinal injury in C57Bl/6 mice. M64HCl-treated mice exhibited smaller ulcers 4 days after ischemic ulcer induction or indomethacin injury. Renal histology and plasma creatinine were normal. Mild hepatic inflammatory changes and ALT elevation were similar among M64HCl-treated mice and controls. M64HCl was concentrated in kidney and gastrointestinal mucosa and functional nephrectomy studies suggested predominantly urinary excretion. Little toxicity was observed in vitro or in single-dose mouse toxicity studies until >1000x higher than effective concentrations. M64HCl, a water-soluble FAK activator, promotes epithelial restitution and intestinal mucosal healing and may be useful to treat gut mucosal injury.