The disclosure provides a compound of the formula (II) and pharmaceutically acceptable salts thereof. The variables, e.g. n, R, R3, R10, X, Y, and Z are defined herein. These compounds act as lactate dehydrogenase inhibitors and are useful for treating cancer and fibrosis. The compounds may be particularly useful for treating forms of cancer in which a metabolic switch from oxidative phosphorylation to glycolysis has occurred. The disclosure also provides pharmaceutical compositions containing a compound of this formula and method for treating patients having cancer, fibrosis, or other conditions in which a metabolic switch from oxidative phosphorylation to glycolysis has occurred.