Integration of MRI and MRS approaches to monitor molecular imaging and metabolomic effects of trabectedin on a preclinical ovarian cancer model

Although several drugs are available to treat recurrences of human epithelial ovarian cancer (EOC), clinical responses often remain short lived and lead to only marginal improvements in patients' survival. One of the new drugs proposed for recurrent platinum‐resistant EOC patients is trabectedin (Trab), a marine‐derived antitumor agent initially isolated from the tunicate Ecteinascidia turbinata and currently produced synthetically. Predictive biomarkers of therapy response to this drug and the potential use of non‐invasive functional MRI and MRS approaches for an early assessment of Trab efficacy have not yet been evaluated, although they might be relevant for improving the clinical management of EOC patients. In the present work we combined functional and spectroscopic magnetic resonance technologies, such as in vivo diffusion‐weighted MRI and ¹H MRS, with ex vivo high resolution MRS (HR‐MRS) metabolomic analyses, with the aim of identifying new pharmacodynamic markers of Trab effectiveness on well characterized, highly aggressive human SKOV3.ip (a HER2‐enriched cell variant derived from SKOV3 cells) EOC xenografts. In vivo treatment with Trab (three consecutive weekly 0.2 mg/kg i.v. injections) resulted in the following: (1) a significant reduction of in vivo tumor growth, along with the formation in cancer lesions of diffuse hyper‐intense areas detected by T₂‐weighted MRI and attributed to necrosis, in agreement with histopathology findings; (2) significant increases in the apparent diffusion coefficient mean and median values versus saline‐treated control tumors; and (3) a significant reduction in the choline‐containing metabolites' signal detected by quantitative in vivo MRS. Multivariate and quantitative HR‐MRS analyses on ex vivo tissue samples revealed Trab‐induced alterations in phospholipid and glucose metabolism identified as a decrease in phosphocholine and an increase in lactate. Collectively, these data identify Trab‐induced functional MRI and MRS alterations in EOC models as a possible basis for further developments of these non‐invasive imaging methods to improve the clinical management of EOC patients.