Jorge D Oldan, Benjamin C Giglio, Eric Smith, Weiling Zhao, Deeanna M Bouchard, Marija Ivanovic, Yueh Z Lee, Frances A Collichio, Michael O Meyers, Diana E Wallack, Amber Abernethy-Leinwand, Patricia K Long, Dimitri G Trembath, Paul B Googe, Madeline H Kowalski, Anastasia Ivanova, Jennifer A Ezzell, Nana Nikolaishvili-Feinberg, Nancy E Thomas, Terence Z Wong, David W Ollila, Zibo Li, Stergios J Moschos
Clinical trials of combined IDO/PD1 blockade in metastatic melanoma (MM) failed to show additional clinical benefit compared to PD1-alone inhibition. We reasoned that a tryptophan-metabolizing pathway other than the kynurenine one is essential. We immunohistochemically stained tissues along the nevus-to-MM progression pathway for tryptophan-metabolizing enzymes (TMEs; TPH1, TPH2, TDO2, IDO1) and the tryptophan transporter, LAT1. We assessed tryptophan and glucose metabolism by performing baseline C11-labeled α-methyl tryptophan (C11-AMT) and fluorodeoxyglucose (FDG) PET imaging of tumor lesions in a prospective clinical trial of pembrolizumab in MM (clinicaltrials...
2023: Oncoimmunology