This study is a single-center, single-arm, open-label, phase II clinical trial designed to evaluate the efficacy and safety of Paclitaxel Polymeric Micelles for Injection for the treatment of patients with advanced pancreatic adenocarcinoma, cholangiocarcinoma, lung cancer, gastric cancer, esophageal carcinoma, or breast cancer that are resistant to Taxanes. Subjects are given paclitaxel polymeric micelles for injection, three weeks constitutes one cycle of treatment. If subject does not develop disease progression , the subject continues treatment until disease progression (RECIST 1.1) or develops an intolerable toxicity, initiation of a new anti-cancer drug, withdrawal from the study, death, or loss of follow-up. This is a single-arm, small-sample clinical study with the primary efficacy goal of objective remission rate (ORR). The parameters of the trial were set: assuming a class I error of 0.025 unilaterally, power=90%, and a 15% improvement in ORR for objective remission rate, a total of 20 subjects would be required, and a total of 25 would be required for enrolment, taking into account a 20% shedding.