In order to deliver and/or release anti-cancer therapeutics at the tumor sites, novel environment-responsive drug delivery systems are designed to specifically respond to tumor microenvironment （such as low pH and hypoxia）. Due to their extraordinary advantages, these environment-responsive drug delivery systems can improve antitumor efficacy, and most importantly, they can decrease toxicity associated with the anti-cancer therapeutics. This review highlights different mechanisms of environmentresponsive drug delivery systems and their applications for targeted cancer therapy.
