Peptide chemistry encounters nanomedicine: Recent applications and upcoming scenarios in cancer

Cancer is the second worldwide cause of death [1]. The considerable efforts to develop cancer treatments have produced only limited results; in fact, the term cancer does not refer to a single disease but rather to a pool of unique diseases with some common features such as the uncontrolled cell proliferation and absence of cell death. The primary tumor exploits the new vascularization to invade other tissues, leading to metastasis and eventually death [1]. Unfortunately, angiogenesis, a key step in the transition from a dormant to a malignant tumor, is also a vital process in growth and development. Surgery and radiotherapy are the primary treatments for local and nonmetastatic cancers, while chemotherapy is the main choice in metastatic cancers. Chemotherapy consists in delivering drugs to the cancer; the bad news is that although many anticancer drugs are highly active in vitro, when transferred in vivo, they also affect healthy tissues and suffer from poor pharmacokinetics and dynamics, which obviously limits their use in a clinical setting [1]. Even when the initial therapy is successful, the risk of cancer recurrence remains a problem. The indiscriminate damages to normal cells, together with the development of multidrug resistance, reinforce the need of an ideal therapy foreseeing effective and targeted treatments: this is still the visionary concept of the ‘magic bullet’ proposed at the very start of the 20th century by the Nobel Prize winner, Paul Ehrlich [2].