Lung cancer is a malignant lung tumor with various histological variants that arise from different cell types, such as bronchial epithelium, bronchioles, alveoli, or bronchial mucous glands. The clinical course and treatment efficacy of lung cancer depends on the histological variant of the tumor. Therefore, accurate identification of the histological type of cancer and respective protein biomarkers is crucial for adequate therapy. Due to the great diversity in the molecular-biological features of lung cancer histological types, detection is impossible without knowledge of the nature and origin of malignant cells, which release certain protein biomarkers into the bloodstream. To date, different panels of biomarkers are used for screening. Unfortunately, a uniform serum biomarker composition capable of distinguishing lung cancer types is yet to be discovered. As such, histological analyses of tumor biopsies and immunohistochemistry are the most frequently used methods for establishing correct diagnoses. Here, we discuss the recent advances in conventional and prospective aptamer based strategies for biomarker discovery. Aptamers like artificial antibodies can serve as molecular recognition elements for isolation detection and search of novel tumor-associated markers. Here we will describe how these small synthetic single stranded oligonucleotides can be used for lung cancer biomarker discovery and utilized for accurate diagnosis and targeted therapy. Furthermore, we describe the most frequently used in-clinic and novel lung cancer biomarkers, which suggest to have the ability of differentiating between histological types of lung cancer and defining metastasis rate.

Nucleic acid aptamers are becoming popular as molecular probes for identification and imaging pathology and, at the same time, as a convenient platform for targeted therapy. Recent studies have shown that aptamers may be effectively used for tumor characterization and as commercially available monoclonal antibodies. Here we present three DNA aptamers binding to whole transformed lung cancer tissues, including tumor cells, connective tissues, and blood vessels. Protein targets have been revealed using affinity purification followed by mass spectrometry analyses, and they have been validated using a panel of correspondent antibodies and 3D imaging of tumor tissues. Each of the proteins targeted by the aptamers is involved in cancer progression and most of them are crucial for lung adenocarcinoma. We propose the use of these aptamers in aptahistochemistry for the characterization of the histological structure of lung adenocarcinoma. The value of the presented aptamers is their application together or separately for indicating the spread of neoplastic transformation, for complex differential diagnostics, and for targeted therapy of the tumor itself as well as all transformed structures of the adjacent tissues. Moreover, it has been demonstrated that these aptamers could be used for intraoperative tumor visualization and margin assessment.

Only one-third of patients with advanced MSS/pMMR endometrial cancer exhibit a lasting response to the combination treatment of Pembrolizumab and Lenvatinib. The combined administration of these two drugs is based on Lenvatinib’s ability to modulate the tumor microenvironment, enabling Pembrolizumab to exert its effect. These findings underscore the importance of exploring tumor microenvironment parameters to identify markers that can accurately select candidates for this type of therapy. An open non-randomized observational association study was conducted at six clinical centers, involving a total of 28 patients with advanced MSS/pMMR endometrial cancer who received Pembrolizumab and Lenvatinib therapy. Using TSA-associated multiplex immunofluorescence, we analyzed the proportion of CD8+ T lymphocytes, CD20+ B lymphocytes, FoxP3+ T regulatory lymphocytes, and CD163+ macrophages in tumor samples prior to immunotargeted therapy. The percentage of CD20+ B lymphocytes and the CD8-to-CD20 lymphocytes ratio was significantly higher in patients who responded to treatment compared to non-responders (responders vs. non-responders: 0.24 (0.1–1.24)% vs. 0.08 (0.00–0.15)%, p = 0.0114; 1.44 (0.58–2.70) arb. unit vs. 19.00 (3.80–34.78) arb. unit, p = 0.0031). The sensitivity and specificity of these biomarkers were 85.71% and 70.59%, and 85.71% and 85.71%, respectively. The proportion of CD20+ B lymphocytes and the CD8-to-CD20 lymphocytes ratio in the stroma of endometrial cancer serves as both a prognostic marker of response to immunotargeted therapy and a prognostic factor for progression-free survival in patients.

Background. By 2020, breast cancer (BC) has become the most frequent malignancy in the world. The most common type of BC is HR+/HER2-negative cancer,2540% of which harbors PIK3CA mutations that affect the catalytic subunit of the PI3K protein. PIK3CA alterations are actionable, as such neoplasms can be treated with a combination of fulvestrant and the PI3K inhibitor alpelisib. As PIK3CA mutations have an extremely versatile effect on the characteristics of a tumor cell, numerous associations of PIK3CA mutations and various clinico-pathological characteristics of BC can be traced. Aim. Our aim was to clarify the information on the frequency and spectrum of PIK3CA mutations in Russian patients with HR+/HER2- advanced BC, and to study the association of PIK3CA mutations with clinical and pathological parameters of BC. Materials and methods. Tissue samples from 694 patients with HR+/HER2- advanced BC (mixed population of primary metastatic and relapsed tumors) who received any line of anti-cancer treatment in Dec 2020 to June 2021 in Russian Federation were analyzed by high-resolution melting, allele-specific PCR, digital droplet PCR and Sanger sequencing (exons 7,9, and 20 of the PIK3CA gene). Mutation rates in different BC subgroups were compared using the Fishers exact test. The age at diagnosis in patients with different PIK3CA status was compared using the MannWhitney U-test. The relationship between the PIK3CA status and the degree of tumor differentiation was compared using the CochraneArmitage test for trends. Luminal A and B BC expression subtypes were distinguished with surrogate IHC markers according to St.-Gallen recommendations (2013). Results. Mutations were identified in 220/694 (32%) BC patients. The three most frequent missense substitutions in the PIK3CA gene (p.E542K, p.E545K, and p.H1047R) accounted for 190/220 (86%) mutations. Associations of PIK3CA mutations with luminal A subtype of BC, low proliferation index, small size of the primary tumor, and absence of signs of hereditary cancer were revealed. Associations of mutations in the kinase domain of PIK3CA (p.H1047R) with late recurrence of locally advanced BC and with non-Slavic ethnic origin of patients were found. Conclusion. PIK3CA mutation rate of 32% confirms high prevalence of mutation in Russian population, with some differences reflecting the ethnic origin of patients.

Relevance. PIK3CA belongs to the top three most frequently mutated genes in breast cancer (BC), especially in estrogen receptor (ER) positive, HER2 negative BC subtype. With an approval of selective PI3K-alpha inhibitor, alpelisib, this alteration has become actionable in ER+HER2- tumors. The frequency and spectrum of PIK3CA alterations in various cohorts is affected by a number of factors, including the distribution of BC expression subtypes, histological types, patient age, and even ethnicity. Aim. Aim of the current study was to characterize the frequency and spectrum of PIK3CA alterations in Russian BC patients. Materials and methods. The analysis of PIK3CA exon 7, 9 and 20 mutations was performed in a cohort of Russian ER+HER2- BC patients by a combination of high-resolution melting analysis, allele-specific PCR, and digital droplet PCR. Results. PIK3CA lesions were identified in 62/206 (30%) patients. Noteworthy, 59/62 (95%) of the identified variants were represented by the three most common p.E542K, p.E545K, and p.H1047R substitutions. The analysis of clinical and morphological characteristics revealed the trends towards association of PIK3CA mutations with older age and more frequent metastatic lung involvement. Conclusion. The obtained data on the frequency and spectrum of PIK3CA somatic aberrations can be helpful when organizing molecular genetic testing of breast cancer patients and using PI3K inhibitors in Russian population.