hCAIX-IN-19 is a sulfonamide inhibitor with an inhibition constant (KI) of 6.2 nM for hCAIX, exhibiting significant selectivity towards hCAIX over hCAI (hCA I/hCAIX = 117).

hCAIX-IN-19 (1) is a small molecule inhibitor designed to target and disrupt the function of the enzyme human carbonic anhydrase IX (hCAIX). By binding selectively to the active site of hCAIX, it prevents the enzyme from catalyzing the reversible hydration of carbon dioxide to bicarbonate and protons, which is a critical physiological process. This inhibition has potential therapeutic implications in oncology, as hCAIX is overexpressed in several cancer types and contributes to tumor growth and metastasis.