Increased hepatic expression of the Forkhead transcription factor FoxM1B in adult mice accelerates hepatocyte proliferation after partial hepatectomy, while in hepatocytes in intact liver the transgenic (Tg) protein is inactive and has no effect on proliferation. To investigate the influence of FoxM1B on liver tumor formation, we examined the effect of sustained enrichment of FoxM1B in the hepatocytes of mice treated with a diethylnitrosamine (DEN)/phenobarbital tumor induction protocol. Tg enrichment of FoxM1B in hepatocytes did not increase the proliferation rate in normal liver tissue even when the protein was localized to the nucleus. However, it did cause an increase in the proliferation rate and size of preneoplastic and early neoplastic lesions, although having no effects on the total numbers of these lesions. As tumors progressed to hepatocellular carcinomas, the additional Tg FoxM1B protein had no effect on cell proliferation, and there was no increase in tumor burden compared to wild-type animals. This suggests that the artificial enrichment of FoxM1B in the liver, which has been suggested as a gene therapy protocol for liver dysfunction with aging, may not be tumorigenic in that organ.

Tissue cross-reactivity (TCR) studies are screening assays recommended for antibody and antibody-like molecules that contain a complementarity-determining region (CDR), primarily to identify off-target binding and, secondarily, to identify sites of on-target binding that were not previously identified. At the present time, TCR studies involve the ex vivo immunohistochemical (IHC) staining of a panel of frozen tissues from humans and animals, are conducted prior to dosing humans, and results are filed with the initial IND/CTA to support first-in-human clinical trials. In some cases, a robust TCR assay cannot be developed, and in these cases the lack of a TCR assay should not prevent a program from moving forward. The TCR assay by itself has variable correlation with toxicity or efficacy. Therefore, any findings of interest should be further evaluated and interpreted in the context of the overall pharmacology and safety assessment data package. TCR studies are generally not recommended for surrogate molecules or for comparability assessments in the context of manufacturing/cell line changes. Overall, the design, implementation, and interpretation of TCR studies should follow a case-by-case approach.

Multiple Sclerosis is a chronic autoimmune neurodegenerative disorder of the central nervous system (CNS) that is characterized by inflammation, demyelination, and axonal injury leading to permeant disability. In the early stage of MS, inflammation is the primary driver of the disease progression. There remains an unmet need to develop high efficacy therapies with superior safety profiles to prevent the inflammation processes leading to disability. Herein, we describe the discovery of BIIB091, a structurally distinct orthosteric ATP competitive, reversible inhibitor that binds the BTK protein in a DFG-in confirmation designed to sequester Tyr-551, an important phosphorylation site on BTK, into an inactive conformation with excellent affinity. Preclinical studies demonstrated BIB091 to be a high potency molecule with good drug-like properties and a safety/tolerability profile suitable for clinical development as a highly selective, reversible BTKi for treating autoimmune diseases such as MS.

An eight-year-old, sexually intact, male, 37 kg crossbred dog was referred for investigation of two acute episodes of intestinal bleeding and severe anaemia within a five-month period. There was no evidence of coagulopathy or underlying systemic disease. Technetium-labelled red blood cell scintigraphy suggested the colon as the site of bleeding. Colonoscopy identified a focal area of dilated and tortuous mucosal blood vessels. Histopathology of the resected colon revealed vascular ectasia (angiodysplasia). At nine months post-resection, the dog remained healthy and free of any overt intestinal haemorrhage.