Over the last few years, immunotherapy, in particular, immune checkpoint inhibitor therapy, has revolutionized the treatment of several types of cancer. At the same time, the uptake in clinical oncology has been slow owing to the high cost of treatment, associated toxicity profiles and variability of the response to treatment between patients. In response, personalized approaches based on predictive biomarkers have emerged as new tools for patient stratification to achieve effective immunotherapy. Recently, the enumeration and molecular analysis of circulating tumor cells (CTCs) have been highlighted as prognostic biomarkers for the management of cancer patients during chemotherapy and for targeted therapy in a personalized manner. The expression of immune checkpoints on CTCs has been reported in a number of solid tumor types and has provided new insight into cancer immunotherapy management. In this review, we discuss recent advances in the identification of immune checkpoints using CTCs and shed light on the potential applications of CTCs towards the identification of predictive biomarkers for immunotherapy.

The aim of the investigation was to study the potential of an innovative microfluidic technology for the isolation of circulating tumor cells (CTCs) from the peripheral blood samples of cancer patients.Materials and Methods. Peripheral blood samples from 5 patients with disseminated malignant tumors of epithelial origin were processed with the use of the microfluidic technology (based on a specifically designed silicone chip). The cells were separated according to their density criterion based on the lateral migration of solid particles in a liquid due to inertial forces. With the help of the designed chip configuration, the cells over 13 μm in size which is larger than the standard size of blood cells were isolated. The resulting target cell fraction was stained by the Romanowsky-Giemsa method. Staining with the fluorescent Anti-Cytokeratin (CK3-6H5)-FITC antibody was carried out to confirm the epithelial nature of the cells, and the DAPI dye was used to contrast the nucleus. The blood of a healthy volunteer and tumor cells of the A549 line were used for the immunocytochemical studies.Results. The tumor cells in peripheral blood (in the number of 1 to 9) were detected in all 5 patients. CTC clusters of 2-5 cells were identified in blood samples from the patients with laryngeal cancer, non-small cell lung cancer, and floor of the mouth cancer. A bright saturated staining of the A549 tumor cells was obtained using the Anti-Cytokeratin (CK3-6H5)-FITC antibody, corresponding to the staining of the cytoskeleton of epithelial cells. Successful nuclear staining with DAPI confirmed that the isolated target cells are not damaged during microfluidic separation.Conclusion. The microfluidic technology that has been used enables effective intact CTCs isolating from the peripheral blood of cancer patients. The epithelial nature of the isolated cells can be confirmed by immunocytochemical studies.

Breast cancer (BC) is one of the most common malignancies and the leading cause of cancer-related death in women worldwide. Currently, mammography and ultrasound are the methods most commonly used for the detection of BC, but these methods have significant limitations in the absence of “classic” visual symptoms of cancer in the breast tissue. In the complicated clinical situations, such methods as magnetic resonance imaging and positron emission tomography are used for the differential diagnosis of breast cancer. Over the past 20 years, the BC imaging capabilities have expanded due to the introduction of optical methods into clinical practice. These methods are based on differences in the optical properties between normal and pathological breast tissues. Optical imaging provides the ability to obtain indirect information about oxygenation, blood supply, delivery and consumption of oxygen in the breast tissue, as well as changes in its scattering properties. We present a clinical case of a woman with enlarged axillary lymph nodes. After the core biopsy of the lymph node, histological examination reveled breast cancer metastasis. The standard imaging modalities, such as digital mammography and ultrasound, did not show the evidence of breast cancer. However, the use of diffuse optical spectroscopy (DOS) allowed the detection of changes in the absorption and scattering coefficients in a small part of the breast tissue characteristic of a malignant tumor. Ultrasound and mammography images of this site of the breast demonstrated the features of benign lesion. After ultrasound-guided biopsy, cytological examination revealed cancer cells. Thus, the method of DOS allowed identification of changes characteristic to malignant tumor that was not detected by routine imaging modalities.