Abstract: The present invention relates to pharmaceutical compositions containing tumor-selective targeted inhibitor glycoconjugates. These bioconjugates are ALK5 inhibitors covalently bound to biocompatible carrier molecules which selectively target and specifically bind to Muc4 that is overexpressed on a variety of tumor cell types. The ALK5 inhibitors are conjugated to tumor targetable glycans through a covalent linker. Preferably the acid-labile linker is designed to be stable in plasma and releases pharmacologically active inhibitors through acid-catalyzed hydrolysis in the acidic environment of the target tumor where the inhibitor activity is restored. Because the glycoconjugates are stable at physiological pH and in plasma, they advantageously reduce undesirable systemic ALK5 inhibitor activity; however, the preferable glycoconjugates are acid-labile conjugates that can be hydrolyzed upon reaching the more acid environment of the tumor.