Platinum deposition in skin as a possible mechanism for peripheral sensory neuropathy (PSN) in patients (pts) with colorectal cancer (CRC) following oxaliplatin-based therapy.

685Background: Oxaliplatin plus fluorouracil (FOLFOX) is a standard treatment for CRC pts. One of the most common and dose-limiting side effects of oxaliplatin is PSN. The mechanism of this phenomenon is poorly understood. Previous studies suggested that higher serum platinum levels were related to more severe neuropathy in testicular cancer pts. Methods: CRC pts who completed adjuvant FOLFOX at least 6 months prior to enrollment are eligible. Baseline demographic and treatment information were collected. EORTC CIPN20 (with EORTC QLQ-C30) questionnaire was used for self-reported PSN symptom assessment. Peripheral blood samples were collected for total/free platinum concentrations using high-performance liquid chromatography with tandem mass spectrometry (HPLC/MS-MS). Skin biopsies were obtained from the lower leg of consented pts. Imaging mass cytometry (IMC) was used to visualize platinum deposition (195Pt) and intra-epidermal nerve fiber (IENF) (PGP9.5-154Sm) in formalin-fixed paraffin embedded (FFPE) s...