Abstract
As part of an investigative nephrotoxicity study, kidney tissues from juvenile rats orally administered dabrafenib at different age intervals between postnatal day (PND) 7 to 35 were investigated by MALDI and LDI imaging mass spectrometry (IMS) to determine the chemical composition of tubular deposits. In the youngest age group (PND 7-13), MALDI IMS demonstrated that a dabrafenib carboxylic acid metabolite was diffusely localized to the regions of tubular deposits (medulla and corticomedullary junction); however, no dabrafenib-related material was detected directly from the deposits. Rather, the LDI IMS analysis determined that the deposits were composed primarily of calcium phosphate. Based on these data, the dabrafenib associated nephrotoxicity, including the formation of tubular deposits, was determined to be age dependent. Furthermore, immature renal function was hypothesized to be responsible for the susceptibility of the youngest pups.