Abstract: Disclosed is a compound of formula (I), wherein Q, U, T, A, a, b, c, and n are as defined herein. Also disclosed are methods of inhibiting ecto-5?-nucleotidase, inhibiting suppression of an antitumor immune response, inhibiting tumor growth of a cancerous tumor, inhibiting metastasis of cancer in a mammal afflicted with cancer, synergistically enhancing a response of a mammal afflicted with cancer undergoing treatment with an immunotherapeutic anti-cancer agent, potentiating an activity of an inhibitor of nicotinamide phosphoribosyltransferase in a mammal undergoing treatment of a mammal with the inhibitor, and treating preeclampsia in a mammal in need thereof, comprising administering to an animal an effective amount of a compound of formula (I).