Despite remarkable improvements in cancer treatment approaches, breast cancer is still the main cause of cancer-related death in women. Its principal cause is the resistance of the cancer cells against conventional anticancer therapeutics, mainly in advanced disease stages. It has been shown that chronic inflammation in the tumor microenvironment facilitates tumor growth and induces resistance toward chemo- and radiotherapy. Overexpression of interleukin-6 (IL-6) cytokine in the tumor microenvironment has been demonstrated in numerous tumors including breast cancer. Tumor cells and tumor-associated fibroblasts are the major sources of IL-6 secretion in the tumor microenvironment. Several studies have demonstrated the immunopathogenic function of IL-6 and its signaling in the tumor growth, metastasis, and therapeutic resistance in the breast cancer. Therefore, it seems that targeting IL-6 and/or its receptor in combination with other potent anticancer therapies may be a potent therapeutic approach for breast cancer therapy.

Chemotherapeutic and cytotoxic drugs are widely used in the treatment of cancer. In spite of the improvements in the life quality of patients, their effectiveness is compromised by several disadvantages. This represents a demand for developing new effective strategies with focusing on tumor cells and minimum side effects. Targeted cancer therapies and personalized medicine have been defined as a new type of emerging treatments. Small molecule inhibitors (SMIs) are among the most effective drugs for targeted cancer therapy. The growing number of approved SMIs of receptor tyrosine kinases (RTKs) i.e., tyrosine kinase inhibitors (TKIs) in the clinical oncology imply the increasing attention and application of these therapeutic tools. Most of the current approved RTK–TKIs in preclinical and clinical settings are multi-targeted inhibitors with several side effects. Only a few specific/selective RTK–TKIs have been developed for the treatment of cancer patients. Specific/selective RTK–TKIs have shown less deleterious effects compared to multi-targeted inhibitors. This review intends to highlight the importance of specific/selective TKIs for future development with less side effects and more manageable agents. This article provides an overview of: (1) the characteristics and function of RTKs and TKIs; (2) the recent advances in the improvement of specific/selective RTK–TKIs in preclinical or clinical settings; and (3) emerging RTKs for targeted cancer therapies by TKIs.

Introduction: Cancer cells apply various mechanisms to induce and enhance immune escape. The complex network of immune-response modulating factors in the tumor microenvironment is a reason for the difficulties encountered when attempting to treat many cancers. Adenosine is a potent immune-modulating factor that can be generated through the degradation of ATP by cooperative action of NTPDase1 (CD39) and ecto-5ʹ-nucleotidase (CD73) molecules. Overexpression of CD73 on tumor and immune cells leads to the presence of a high concentration of this factor in the tumor region. Upregulation of CD73 is associated with the overproduction of adenosine; it suppresses anti-tumor immune responses and helps proliferation, angiogenesis and metastasis. Areas covered: We attempt to clarify the immunobiology of CD73 in association with its role in cancer development, angiogenesis and metastasis. Moreover, we have reviewed CD73-targeting studies and highlighted CD73 as a potent target for cancer immunotherapy. Expert opinion: It seems that blockade of CD73 in combination with immune checkpoint inhibitors such as anti-PD-L1 and anti-CTLA-4, can be a novel promising therapeutic strategy that can be evaluated in the future trials.