Abstract 1210: Preclinical pharmacology and repeated dose toxicity of the novel agonistic TWEAK receptor binding antibody BAY-356

TWEAK receptor (TWEAKR, FN14) is a member of the tumor necrosis factor receptor superfamiliy and is highly expressed in a variety of human solid tumor types, and its overexpression is associated with poor prognosis and metastasis. To explore targeting of TWEAKR for cancer therapy we have generated the novel, anti-TWEAKR antibody BAY-356. Its potent agonistic activity leads to TWEAKR hyperactivation and subsequent induction of cell death in vitro and tumor growth inhibition in vivo. BAY-356 is a fully human aglycosylated antibody (Kd ∼ 10nM) that binds to a novel epitope within the TWEAKR ectodomain of various species as determined by BiaCore. In vitro, BAY-356 showed strong agonistic activity on TWEAKR-positive tumor cells, including activation of NFκB- and STAT1 pathways, increase of TWEAKR protein expression, increased IL-8 secretion, caspase 3/7 activation, and proliferation inhibition in a dose-dependent manner. BAY-356 inhibited tumor growth in several TWEAKR-positive tumor models (NCI-H1975, WiDr, ScaBER, and HN10321) with growth inhibition rates of 49-71% when treated with 3-10 mg/kg BAY-356 twice weekly for up to 3 weeks. The activity of BAY-356 was independent of ADCC activation. In a preventative syngeneic CT26-tumor model in Balb/c mice, BAY-356 induced complete responses. Anti-tumor activity of BAY-356 was associated with high tumor levels of TNF alpha protein. To investigate the toxicity of BAY-356, a repeated dose-toxicity study was performed in Cynomolgus monkeys. Animals were dosed with 10, 20, and 40 mg/kg by weekly intravenous injection for 4 weeks. Compound-related clinical findings consisted of an increase of the serum markers amylase and lipase from 10 mg/kg onwards, urea and creatinine from 20 mg/kg onwards and the transaminases ALT and GDPH at 40 mg/kg. Histopathological evaluation revealed focal ductular epithelial hyperplasia with periductular fibrosis in the exocrine pancreas (at 10 & 20 mg/kg), renal tubular hyperplasia and degeneration, Bowman capsule hyperplasia, and glomerulosclerosis in the kidney starting at 10 mg/kg and bile duct hyperplasia in liver at 20 mg/kg and higher. The HNSTD was set as the highest tested dose of 40 mg/kg. Immunohistochemical analysis of TWEAKR expression in these organs demonstrated a dose dependent induction and increase when compared to untreated controls which correlated with the histopathological findings. From these data it can be concluded that hyperactivation of TWEAKR signaling by BAY-356 l