A Phase 1, Randomized, Double-Blind, Placebo-Controlled, Single Ascending Dose Trial of AWZ1066S, an Anti-Wolbachia Candidate Macrofilaricide.

AWZ1066S has been developed as a potential treatment for the neglected tropical diseases lymphatic filariasis and onchocerciasis. AWZ1066S targets the Wolbachia bacterial endosymbiont present in the causative nematode parasites. This phase 1, first-in-human study aimed to assess the safety and pharmacokinetics of AWZ1066S in healthy human participants. In a randomized double-blind, placebo-controlled, single ascending dose study, healthy adults received a single oral dose of AWZ1066S (or placebo) and were followed up for 10 days. The planned single doses of AWZ1066S ranged from 100 to 1600 mg, and each dose was administered to a cohort of 8 participants (6 AWZ1066S and 2 placebo). In total 30 people participated, 18 (60%) female, median age 30.0 years (minimum 20, maximum 61). The cohorts administered 100, 200, 300, and 400 mg of AWZ1066S progressed unremarkably. After single 700-mg doses all 4 participants developed symptoms of acute gastritis and transient increases in liver enzymes. The severity of these adverse events ranged from mild to severe, with 1 participant needing hospital admission. Pharmacokinetic analysis indicated that AWZ1066S is rapidly absorbed with predictable pharmacokinetics. In conclusion, safety concerns prevented this study from reaching the human exposures needed for AWZ1066S to be clinically effective against lymphatic filariasis and onchocerciasis.

A novel animal model of tegafur-induced hand-foot syndrome.

Hand-foot syndrome (HFS) is a common side effect of fluoropyrimidine anticancer drugs and often becomes a dose-limiting manifestation of toxicity once it occurs. The precise mechanism of HFS remains unclear, and effective measures to prevent or relieve it are currently limited. To investigate the pathogenesis of HFS and effective measures for treating or preventing it, establishment of animal models is crucial. Here, we gave male SD rats 170 mg/kg of tegafur (prodrug of 5-FU) daily for 35 days and evaluated their clinical and histopathological characteristics and pain-related behavioral tests. TUNEL-positive apoptotic cells and 5-FU concentrations in the plantar skin were also evaluated to investigate the mode of toxicity. Tegafur treatment induced hypersensitivity to mechanical pressure on the plantar surface beginning in Week 3, with decreased locomotor activity. Focal desquamation of the plantar skin was observed almost concomitantly and gradually worsened to palmar and plantar skin thickening with severe desquamation, cracks, or both. Histopathological lesions in the plantar skin at treatment end included desquamation and thickening, with epidermal cell swelling and spongiosis and focal inflammation in the dermis. The time-course of development and the characteristics of the tegafur-induced skin lesions were highly similar to those in human fluoropyrimidine-induced HFS, indicating that a HFS rat model was successfully established. Localized high concentrations of 5-FU in the palmar and plantar skin, with increased apoptosis, are likely involved in the mode of toxicity. Our model should clarify the pathogenesis of HFS, providing new insights into the best supportive care and prevention.

Toxicologic Pathology Forum: Opinion on Approaches for Reporting Toxic and Adverse Dose Levels in Nonclinical Toxicology Studies Supporting the Development of Anticancer Pharmaceuticals.

The advancement of an investigational new drug in humans is a significant developmental milestone. In first-in-human (FIH)-enabling toxicology studies, the highest dose without a test article-related adverse effect (no-observed-adverse-effect-level [NOAEL]) serves as the basis for deriving a safe FIH starting dose. For anticancer pharmaceuticals, the FIH dose may be calculated using the highest non-severely toxic dose (HNSTD) in nonrodent models or the dose severely toxic to 10% (STD10) in rodents. Given the practice of reporting the NOAEL, but the lack of regulatory requirements to do so for anticancer pharmaceuticals, we conducted an informal survey of 20 companies to answer the question "How is our industry reporting toxic/adverse dose levels in FIH-enabling toxicology studies for anticancer indications?" The data indicated 4 reporting approaches, each providing a path to regulatory acceptance. Within the integrated toxicology study report, 45% of respondents report the HNSTD/STD10, 25% report the NOAEL, 20% report both the HNSTD/STD10 and NOAEL, and 10% do not define either, reserving definitions for regulatory submissions. One reporting approach may be preferred over another for reasons including consistency across indications, repurposing pharmaceuticals, regulatory feedback, or simplicity. The reporting approach should be defined in advance of study initiation, and the pathologist should provide context to support the chosen approach.

Antibody-drug conjugate MORAb-202 exhibits long-lasting antitumor efficacy in TNBC PDx models.

The antibody-drug conjugate (ADC) MORAb-202, consisting of farletuzumab paired with a cathepsin B-cleavable linker and eribulin, targets folate receptor alpha (FRA), which is frequently overexpressed in various tumor types. MORAb-202 was highly cytotoxic to FRA-positive cells in vitro, with limited off-target killing of FRA-negative cells. Furthermore, MORAb-202 showed a clear in vitro bystander cytotoxic effect in coculture with FRA-positive/negative cells. In vivo antitumor efficacy studies of MORAb-202 were conducted with a single administration of MORAb-202 in triple-negative breast cancer (TNBC) patient-derived xenograft (PDx) models expressing low and high levels of FRA. MORAb-202 exhibited durable efficacy proportional to tumor FRA expression. Toxicology studies (Q3Wx2) in nonhuman primates suggested that the major observed toxicity of MORAb-202 is hematologic toxicity. Overall, these findings support the concept that MORAb-202 represents a promising investigational ADC for the treatment of TNBC patients.

Farletuzumab, a monoclonal antibody directed against folate receptor alpha, shows no evidence of teratogenicity in cynomolgus monkeys.

Farletuzumab is a humanized monoclonal antibody targeting human folate receptor alpha, which is being developed as an anti-cancer drug. A non-human primate reproductive study was conducted to evaluate whether it could cause any embryonic or fetal abnormalities. Farletuzumab was administered intravenously to pregnant cynomolgus monkeys (n = 16/group) at doses of 0 or 67.5 mg/kg once weekly during gestation day (GD) 20 through 97. C-section was performed on GD100 ±â€¯2, and fetuses were evaluated for morphologic (external, visceral and skeletal) effects. No farletuzumab-related changes were observed in maternal animals or fetuses, which are supported by the fact that farletuzumab has no effects on cellular uptake of folate. These data support the potential use of farletuzumab for oncologic indications during pregnancy.

Elevated cardiac 3-deoxyglucosone, a highly reactive intermediate in glycation reaction, in doxorubicin-induced cardiotoxicity in rats.

3-Deoxyglucosone (3-DG) is a highly reactive carbonyl intermediate in glycation reaction (also known as Maillard reaction) and plays an important role in diabetic complications. We investigated the potential involvement of 3-DG in doxorubicin (DXR)-induced cardiotoxicity. Male Crl:CD(SD) rats received intravenous injections of DXR at 2mg/kg, once weekly, for 6 weeks, with/without daily intraperitoneal treatment with 3-DG scavenging agents, i.e., aminoguanidine (AG, 25mg/kg/day) and pyridoxamine (PM, 60mg/kg/day). Cardiac levels of 3-DG, thiobarbituric acid reactive substances (TBARS), fructosamine, and pentosidine, plasma glucose levels and cardiac troponin I (cTnI), echocardiography, and histopathology were assessed at 4 and 6 weeks after treatment. Cardiac 3-DG levels were significantly increased by DXR treatment at 4 and 6 weeks. Cardiac fructosamine levels and plasma glucose were not altered by DXR; however, TBARS levels in the heart were significantly increased at 4 and 6 weeks, suggesting that the enhanced generation of 3-DG is not attributed to any abnormal glycemic status, but may be related to oxidative stress by DXR. An advanced glycation end-product, pentosidine, was significantly increased by DXR treatment at 6 weeks. Intervention by AG and PM ameliorated the DXR-induced echocardiographic abnormalities, increased cTnI in plasma, and histopathological lesion as well as normalizing the elevation of 3-DG and pentosidine levels. These results suggest that 3-DG is generated by DXR and involved, at least in part, in the pathogenesis of DXR-cardiotoxicity through glycation reaction.

Involvement of advanced glycation end-products, pentosidine and N(epsilon)-(carboxymethyl)lysine, in doxorubicin-induced cardiomyopathy in rats.

In the pathogenesis of doxorubicin (DXR)-induced cardiomyopathy, oxidative stress appears to play an important role. It has been reported that pentosidine and N(epsilon)-(carboxymethyl)lysine (CML), advanced glycation end-products (AGEs), are formed by the combined processes of glycation and oxidation and play a significant role in the process of complications of diabetic mellitus. We investigated the potential involvement of AGE formation in DXR-induced cardiomyopathy in rats. Male Crl:CD(SD) rats received intravenous injection of DXR at 2mg/kg or saline once weekly for 8 weeks, with or without daily treatment with the AGE formation inhibitors, aminoguanidine (AG, 25 mg/kg/day, i.p.) and pyridoxamine (PM, 60 mg/kg/day, i.p.). Time-course experiments revealed significantly increased pentosidine and CML in the heart in the DXR group from Week 6. These findings coincided with a decrease in fractional shortening (FS), an index of cardiac function, and the development of cardiomyopathy characterized by vacuolated hypertrophic myocardial fibers. There was a significant correlation between the myocardial AGEs and FS or plasma cardiac troponin-I. Immunohistochemical staining showed localization of pentosidine to the cytoplasm of vacuolated myocardial cells. In DXR-treated rats, oxidative stress was enhanced prior to any observed increase in pentosidine and CML levels in the heart. Hyperglycemia was not observed throughout the study period. Intervention by AG or PM treatment ameliorated the functional and morphological changes induced by DXR in the heart, in addition to lowered myocardial pentosidine and CML levels. These results suggested that DXR accelerates the formation of pentosidine and CML in the heart through enhanced oxidative stress and that AGE formation is involved in DXR-induced cardiomyopathy. The findings may enable development of novel preventive therapies and predictive biomarkers of DXR-induced cardiomyopathy.

Effects of reduced food intake on toxicity study parameters in rats.

This study comprehensively describes the effects of various levels of food reduction on a wide range of toxicological parameters in dietary-optimized rats (fed with approximately 75% of ad libitum food consumption daily; 16 g and 22 g/day for females and males, respectively) that has been established as a nutritionally appropriate and well-controlled animal model in conducting toxicity studies. Toxicological parameters, including general condition, ophthalmology, clinical pathology and anatomic pathology, were examined in dietary-optimized Crl:CD(SD) female and male rats fed 16 g and 22 g/day (control), 12 g and 17 g/day (75% group), 8 g and 11 g/day (50% group), or 4 g and 6 g/day (25% group), respectively for 2 weeks. There was mortality and morbidity including reddish urine in 25% group females. The reddish urine was identified as "hemoglobinuria" that resulted from extra/intra-vascular hemolysis induced by severe food reduction. Hemoconcentration, decreased leukocytes and platelets, decreases in nutritional elements (serum glucose, protein, and lipids), increased aspartate aminotransferase and alanine aminotransferase, imbalanced electrolytes, and/or decreased urinary pH were observed in all restriction groups. Histopathologically remarkable changes included erythrophagocytosis in the spleen/liver and renal tubular necrosis with hyaline cast/droplets in 25% group; in addition to bone marrow depletion, lymphoid depletion in thymus/spleen/lymph node, and/or decreased secretion in the prostate/seminal vesicle in all restriction groups. Most of these changes were considered attributable to nutritional deficiency, dehydration, accelerated protein catabolism, stress and/or hemolysis secondary to severe food reduction. These results will enable toxicologists to help distinguish primary drug-induced effects from secondary changes associated with decreases in food consumption.

Beneficial effect of moderate food restriction in toxicity studies in rats.

Moderate food restriction (FR) has been established as a nutritionally appropriate and well-controlled method with long-term beneficial effects in conducting toxicity and carcinogenicity studies in rodents. This study describes the early effects of moderate FR on toxicity study parameters in rats and on the variability of these parameters. Physical signs, body weight, food and water consumption, and clinical pathology parameters were examined in a 4-week study in which rats were moderately food-restricted or fed ad libitum (AL). There were no diet-related differences in physical signs, hematology or urinalysis. FR-related changes were observed in body weight and serum biochemistry; however, most of the changes involved anti-aging alterations and/or physiological adjustment to FR. Moderate FR resulted in low variability and good reproducibility in body weight. The present results indicate that moderate FR does not impair study parameters and increases statistical sensitivity. Therefore, a moderate FR feeding regimen is beneficial not only for long-term but also for short-term toxicity studies in rats.

Studies on the synthesis and opioid agonistic activities of mitragynine-related indole alkaloids: discovery of opioid agonists structurally different from other opioid ligands.

Mitragynine (1) is a major alkaloidal component in the Thai traditional medicinal herb, Mitragyna speciosa, and has been proven to exhibit analgesic activity mediated by opioid receptors. By utilizing this natural product as a lead compound, synthesis of some derivatives, evaluations of the structure-activity relationship, and surveys of the intrinsic activities and potencies on opioid receptors were performed with guinea pig ileum. The affinities of some compounds for mu-, delta-, and kappa-receptors were determined in a receptor binding assay. The essential structural moieties in the Corynanthe type indole alkaloids for inducing the opioid agonistic activity were also clarified. The oxidative derivatives of mitragynine, i.e., mitragynine pseudoindoxyl (2) and 7-hydroxymitragynine (12), were found as opioid agonists with higher potency than morphine in the experiment with guinea pig ileum. In addition, 2 induced an analgesic activity in the tail flick test in mice.