Plasma Cytokeratin 18 and fecal Alpha-1 Antitrypsin concentrations in dogs with osteosarcoma receiving carboplatin chemotherapy.

Gastrointestinal (GI) toxicosis is a common side effect of cytotoxic chemotherapy treatment in humans and dogs. Measurement of cytokeratin 18 (CK18), an intracellular structural protein released during epithelial apoptosis, and Alpha1-Antitrypsin (A1AT) in faeces provides a mechanism for evaluating damage to the intestinal mucosa secondary to cytotoxic chemotherapy. Our goal was to evaluate the clinical utility of plasma CK18 and faecal A1-AT levels as non-invasive biomarkers of cytotoxic chemotherapy induced GI toxicity. We conducted a prospective cohort study in dogs (N = 10) with osteosarcoma undergoing amputation followed by carboplatin chemotherapy. We hypothesized that plasma CK18 and faecal A1-AT levels would increase following carboplatin administration due to drug-induced GI epithelial damage/apoptosis, and that plasma CK18 and faecal A1-AT levels would correlate with severity of GI toxicity. Mean baseline plasma CK18 concentration was variable amongst patients; however, CK18 concentration prior to carboplatin chemotherapy treatment was not significantly different from CK18 levels after treatment. There was significant intra and inter-patient variability in mean faecal A1-AT levels at baseline. Mean A1-AT concentration did not change significantly from day 0 to day 21. Gastrointestinal toxicity was minimal; therefore, we were unable to determine the association of plasma CK18 and faecal A1-AT concentrations with development of GI toxicosis. In this study population, plasma CK18 and faecal A1-AT concentration were not clinically useful biomarkers for the detection of GI toxicosis secondary to carboplatin administration. Further prospective evaluation of CK18 and A1-AT as biomarkers of drug-induced GI toxicity is warranted in a larger cohort of dogs receiving cytotoxic chemotherapy. AVMA clinical trial registration number: AAHSD004827.