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e18068 Background: The purpose of this study was to assess the etiology of oral candidiasis in patients with oropharyngeal cancer as potential causative agents of invasive candidiasis and to analyze in vitro activity of isolates of Candida fungi to caspofungin, fluconazole and voriconazole. Methods: Isolates were obtained in a prospective study from the oral mucosa of patients with oropharyngeal cancer in 2020-2021. Identification of Candida fungi was performed using MALDI-TOF MS. Result of activity of isolates to caspofungin, fluconazole and voriconazole after 24 hours of incubation were registered according to CLSI M60-ED2:2020 (Performance Standards for Antifungal Susceptibility Testing of Yeasts). Results: 45 patients aged 30-85 years were examined. 92 isolates of Candida fungi were obtained: C. albicans 31.5% (29) and Candida non albicans 68.5% (63). Candida non albicans included: C.parapsilosis 30.2% (19), C.glabrata 28.6% (18), C.krusei 19.0% (12), C.tropicalis 15.9% (10), C.guilliermondii 6.3% (4). Candida carriage on the oral mucosa was noted in 62.2% of patients in the first days of hospitalization, with a predominance of C. albicans 42.8% compared with 32.1% after chemotherapy (p = 0.003) and 25.0% after antibiotic therapy. The distribution of species varied depending on the age of patients. The table presents comparative activity of caspofungin, fluconazole and voriconazole (susceptible (S), moderately resistant (I), resistant (R)) in % to Candida spp. High sensitivity to caspofungin was noted for both C.аlbicans and Candida non albicans. Voriconazole was characterized by lower sensitivity and natural resistance in C.glabrata which makes it less suitable for empirical therapy, as well as fluconazole. Conclusions: Candida non albicans (68.5%) were predominant in the oral candidiasis etiology in patients with oropharyngeal cancer, which was probably due to the use of azole antimycotics for prevention and empirical therapy. Reduced activity to voriconazole and fluconazole was observed in the dominant isolates, given the natural resistance of C. krusei to fluconazole and C. glabrata to voriconazole. Acquired azole resistance was noted for C. parapsilosis and C. albicans. The pathogen type should be determined in all cases of invasive candidiasis to exclude natural resistance and sensitivity to azoles before starting therapy.[Table: see text]

e12588 Background: Breast reconstruction after skin-sparing mastectomy for breast cancer (BC) is an important rehabilitation stage. Its results depend on many factors, with the immune system status playing the main role. The purpose of this study was to identify characteristics of the local lymphocyte populations in patients with breast cancer in the early postoperative period after reconstructive surgery with textured implants (TI). Methods: The study included 30 patients aged 32-68 years, mean age 42.9±1.98 years, with stage I-IIb BC (monocentric nodular BC, T1N0M0 - T2N1M0). All patients underwent skin-sparing mastectomy with level II axillary lymph node dissection and immediate implant reconstruction in 2017-2019. Populations and subpopulations of lymphocytes were determined in wound fluid from the cavity with TI on days 1, 3-4 and 7 after the surgery using the FacsCanto II flow cytometer (Becton Dickinson, USA) with markers: CD3 FITC /CD15+56 PE /CD45 PerCP /CD4 PE-Cy7/CD19 APC/ CD8 APC-Cy7; CD45RA FITC /CD45RO PE /CD3 PerCP /CD8 APC; CD45RA FITC /CD62L PE /CD3 PerCP /CD4 APC; CD4 FITC /CD127 PE /CD3 PerCP / CD25 APC-Cy7; CD4 FITC /CD38PE /CD3 PerCP / HLADR APC. At least 50,000 cells were accumulated in each sample for the analysis. Results: The relative number of total lymphocytes exceeded the initial values by 3.3 (p=0.025) and 10.9 (p=0.012) times, respectively, on days 3-4 and 7 after surgery. Levels of CD3+CD4+ cells increased gradually and were 29% (p=0.042) higher by day 7, while levels of CD3+CD8+ decreased during the whole observation period. Levels of Tregs did not change, while B lymphocytes decreased by 36% (p=0.035) and 67% (p=0.026), respectively, on days 3-4 and 7. The levels of activated T lymphocytes increased by 33% (p=0.038) on days 3-4, compared with the initial values, probably due to the elevation of CD3+CD8+ levels (by 32%, p=0.037). The number of activated T lymphocytes with the CD3+CD4+ phenotype increased by 44% (p=0.024) on days 6-7. While the content of CD3+CD4+ cells with early activation markers (CD38+) significantly decreased (by 40%, p=0.031) and remained the same on days 3-4 and 7, the number of CD3+CD8+ with similar markers (CD38+) significantly increased by 28% (p=0.044) and 43%. Conclusions: TI implantation was accompanied by the activation of the cytotoxic T unit during the observation period, together with a decrease in immunosuppressive populations of lymphocytes, which may indicate a favorable development of the patient's body reaction.

e20515 Background: Study of the effect of photodynamic therapy (PDT) with Photoditazine using a high-energy laser at various periods after tumor transplantation on the dynamics of growth of experimental Lewis lung carcinoma in mice. Methods: The study included 176 male C57Bl6 mice weighing 18-20 g with Lewis lung carcinoma (LLC) transplanted subcutaneously. The animals received experimental PDT sequential overlapping of fields of influence (662 nm, 3 W, Photoditazine 25 mg/kg, 300 J/cm2). Animals received PDT on day 11 after the transplantation (experimental series I) and on day 21 (experimental series II). Experimental groups were divided in dependence on the exposure area (to the primary tumor -1gr, thorax (area of metastases)-2 gr and to both zones-3 gr). Animals with tumors without PDT were used as controls. Results: PDT with Photoditazine using the 3W laser stimulated the growth of primary tumor node. The degree of stimulation depended on the time of PDT. Increase in tumor sizes differed already on day 7 after PDT at various periods of the LCC growth. During PDT on the 11th day from the moment of tumor inoculation, the percentage of growth on the 7th day after the end of treatment was 60.7; 69.6 and 86.7% in groups 1, 2 and 3, respectively. In the groups of animals that underwent PDT on the 21st day of the growth of the grafted tumor on the 7th day after the end of treatment, the percentage of tumor growth was 20; 35.6 and 24.4% in groups 1, 2 and 3, respectively. Increase in the median survival was registered in experimental animals with PDT on 22.6% compared to control. A smaller increase in tumor volume was observed in animals receiving PDT to the primary tumor, and the group receiving therapy to both areas was in between. Conclusions: The study was shown that with an earlier initiation of PDT, a greater stimulation of tumor growth was revealed than with therapy at a later date. The revealed characteristics of the development of experimental LLC at PDT exposure allows further selection of parameters for photodynamic therapy regimens.

e17578 Background: Cytostatic treatment was shown to influence significantly reactivation of latent viral infections. Our purpose was to study the possible effect of cetuximab on activation of herpesvirus infections. Methods: The blood serum of patients with histologically confirmed laryngeal squamous cell carcinoma was studied before and after chemotherapy. The main group included 9 pts receiving cetuximab+cisplatin+5-fluorouracil, the control group – 9 pts, cisplatin+5-fluorouracil. Antibodies (AB) against viral proteins were detected by ELISA. Results: 6 (66.7%) pts of the main group had primary advanced cancer, 3 (33.7%) – recurrent laryngeal cancer; in control group - 7 (77.7%) and 2 (22.2%), respectively. All pts in both groups were seropositive for HSV 1,2, CMV and EBV before chemotherapy; 4 (44.4%) pts in main group and 7 (77.8%) controls were HPV 6 seropositive. Serological markers of activation of herpes virus infection (IgM or IgG against early viral proteins) after chemotherapy were detected in the main group in 8 (88.9%): HSV 1,2 - 5 (55.6%), CMV - 2 (22.2%), EBV - 3 (33.3%). HSV 1,2, CMV and EBV infections in the control group were activated equally often and found in 3 (33.3%) pts. Clinical signs of herpes virus infection were not observed in either group. A sharp decline in AB titers, sometimes up to their complete disappearance, was registered in 3 (33.3%) pts in the main group and in 6 (66.7%) controls. 1 pt of the main group showed a decline in EBV AB titers and absence of HPV 6 AB titers, 1 pt - a decline in CMV and EBV AB, 1 pt - a decline in HSV 1,2, CMV and EBV AB and absence of HPV 6 AB titers. 2 pts of the control group showed a decrease in HPV 6 AB, 2 pts – their absence, 2 pts – absence of HPV 6 AB and a decline in HSV 1,2, CMV and EBV AB. It could be associated with a greater degree of bone marrow hematopoiesis inhibition during cytostatic therapy. Lymphopenia was registered in the control group more frequently than in the main one. Conclusions: Cetuximab inclusion into chemotherapy does not have an additional negative impact on the development of viral infectious complications. A higher rate of registration of specific antibodies typical of the acute infection phase in the cetuximab group could indicate an adequate response to viral infection.