Chemotherapeutic agents for treating various cancers show considerable side effects and toxicity. Often cancer relapses after initial response to the chemotherapy. Tumor cells are heterogeneous and have the progenitor stem cells which can renew, causing the relapse of the disease. To overcome drug resistance, metastasis, and relapse in cancer, targeted therapy is a promising approach. Targeted delivery of chemotherapeutic agents decrease toxicity and improve efficacy for cancer treatment. We have designed targeted, stimuli-responsive echogenic polymeric vesicles (polymersomes) to not only transport, and subsequently, release a chemotherapeutic drug in the nuclei or cytosol of cancer cells and image by diagnostic frequency ultrasound. Targeted polymersomes carry chemotherapeutic drugs through the body, recognize the cancer cells, internalize, and release the encapsulated chemotherapeutic drug in response to increased reducing agent concentration. We have employed different targeting moieties such as, neuropilin-1 peptide and prostate-specific membrane antigen agonist. We prepared redox-sensitive targeted polymersomes encapsulating the hydrophobic chemotherapeutic drug in the treatment of cancer cells, including cancer stem cells. Different formulation of targeted stimuli-responsive polymersomes was tested on monolayer as well as three-dimensional spheroids. Our results indicate that targeted polymersomes encapsulating both drugs are significantly reducing the cell viability in cancer cells. We also established the preliminary data on the penetration of iRGD peptide-decorated polymersomes in a xenograft mouse model of pancreatic cancer.