No abstract

435 Background: The aim of the present study was to determine to the effect of HER2, dMMR, PD-L1 status in the primary tumor and in metastasis to the regional lymph node of GC patients. Methods: A total of 44 patients with primary loco-regional (N+) gastric adenocarcinoma were recruited, and two formalin-fixed paraffin-embedded (FFPE) tumor-containing blocks of each patient (one block with primary tumor and one block with metastasis to the regional lymph node)were selected for HER2, dMMR, PD-L1 (CPS) immunohistochemical (IHC) assay. Clinicopathological characteristics were recorded, and intertumoral heterogeneity of HER2, dMMR, PD-L1 IHC expression was determined. Results: The study included 19 women and 25 men, 30 patients had Laurén’s intestinal type of cancer, 14 had a Laurén’s diffuse type. In 5 patients (11.4%) overexpression of Her-2 neu was detected, and heterogeneity was detected in all five cases: in three patients with HER2 overexpression in the primary tumor, no overexpression was detected in the metastasis to the regional lymph node, in two cases overexpression was detected in the metastasis, while no overexpression was observed in the primary tumor. 2 patients showed signs of dMMR (4.5%), in one case, heterogeneity in dMMR status was also revealed: signs of dMMR in the primary tumor and its absence in regional metastasis (pMMR). Assessment of PD-L1 status was carried out using the CPS formula. Ten patients (22.7%) had a negative PD-L1 status (CPS=0) both in the primary tumor and in regional metastasis. Positive PD-L1 status in the primary tumor: in 24 patients CPS= 0-5 (54.5%), in 5 patients CPS= 5-10 (11.4%) and 5 patients CPS= 10 or more (11.4% ). Positive PD-L1 status in regional lymph node metastasis: in 24 patients CPS= 0-5 (54.5%), in 5 patients CPS= 5-10 (11.4%) and in 5 patients CPS= 10 or more ( 11.4%). In 5 cases (11.4%) marked heterogeneity in PD-L1 status between the primary tumor and its regional metastasis (1 case with dMMR heterogeneity). Conclusions: The research findings in this paper indicate that the intertumoral heterogeneity of HER2 overexpression is common in GC patients, We highly recommend multi-block HER2 assessment for accurate diagnosis of GC. Given the rarity of status detection dMMR, a study in a larger number of patients is required, however, our data also confirm the presence of heterogeneity in dMMR status, and probably the possibility of metastasis of a more aggressive pMMR clone. Heterogeneity in PD-L1 status is quite rare and amounted to only 11.4%, which also has important practical significance.

e18059 Background: We investigated the efficacy and safety of docetaxel + cisplatin (DC) induction chemotherapy vs TPF in patients with locally advanced HNSCC. Methods: Under our observation there were 22 patients in HNSCC (63,6% men and 36,4% women, aged 43 to 74 years (58.7±9.4 (95% CI 55.0-62.4)). The control group consisted of 18 patients (72,2% men and 27,8% women, aged 43 to 73 years (53.9±8.8 (95% CI 49.6-58.3). Both groups were comparable in terms of location, stage (III-IVA) and tumor differentiation. The patients of group 1 received DC (docetaxel 75 mg/m2 + cisplatin 75 mg/m2; q3w) as induction chemotherapy (ICT), while patients in the control group received TPF. Results: The planned number of ICT cycles (No. 3) in group 1 was received by 100% pts. and in the control group - 77.78% pts. (p = 0.02). At the control assessment according to RECIST 1.1, PR was registered in 77.3% pts. of group 1 vs 55.5% pts. in control group (p = 0.14), SD - in 22.7% vs 33.3: (p = 0.45), PD was registered only in patients of the control group - in 11.2% (p = 0.11). The frequency of registration of AEs: diarrhea gr.1-3 - 9.1% pts. group 1 vs 33.3% of pts. the control group (p = 0.06), nausea gr.1 -2 - 9.1% vs 22.2% (p= 0.25), asthenia gr. 1-2 - 4.5% versus 16.7% (p = 0.20), anemia gr. 1-2 - 9.1% vs. 16.7% (p = 0.47), neutropenia gr. 3-4– 4.5% versus 16.7% (p = 0.20). Reduction of doses of cytostatic up to 50% was performed in 4.5% pts. in group 1 and 16.7% pts. in the control group (p = 0.20). Conclusions: Induction chemotherapy in DC mode may be an effective and safe regimen in certain groups of patients with HNCH (for example, in patients with contraindications to 5-FU infusions, as well as in patients with high-risk HHNH for alternative surgical treatment or concurrent CRT as initial treatment of localized and locally advanced HNSCC.

e15649 Background: We investigated the possibility of using accompanying therapy with enterosorbent in CRC patients receiving adjuvant chemotherapy. Methods: 40 pts (62 years [54.0-68.5]) with CRC (II-III) after radical surgery were randomized in 2 groups (1:1). Patients in the group 1 received ACT (XELOX), patients in group 2 received XELOX and enterosorbent "Polysorb" 30 mg orally, daily from 16 to 20 days of the ACT cycle. Results: The use of an enterosorbent can significantly reduce the manifestations of gastrointestinal toxicity: vomiting (5.0% vs 35.0%; p = 0.018), diarrhoea (5.0% vs. 40.0%; p = 0.008), flatulence ( 25.0% vs 70.0%; p = 0.004), constipation (0 vs 20.0%; p = 0.035) and abdominal pain (15.0% vs 50.0%; p = 0.018). In group 2, already by the 2nd cycle, the median scores on the QLQ-C30 symptomatology scale amounted to 22.0 points [14.0-28.5] vs 29.9 points [23.0-33.0] in the control group (p = 0.0441). By the 3 cycle in group 2, the average score on the QLQ-C29 symptomatic scale was 13.0±5.2 points (95% CI 10.5-15.4) and was significantly lower than in the control group (18.0±7.8 points (95% CI 14.3-21.6); p = 0.0224). When assessing the general condition according to the results of the analysis of the QLQ-C30 questionnaire, in the control group of patients there was a significant decrease in the number of points already by the beginning of the 2nd cycle of ACT - before the start of cycle 2 of ACT(p = 0.0369) and cycle 4 of ACT (p = 0.0447). Score of EQ-5D in the control group, significant decreases before 2 (from 84.9±6.4 points (95% CI 81.9-87.9) to 80.5 [77.55-86, 5]) (p = 0.0477) and 3 cycle ACT (from 80.5 [77.55-86.5] to 77.0±4.7 (95% CI 74.7-79.2)) (p = 0.0170), as well as a decrease in patient satisfaction with their condition at the time of the start of the 4th cycle of ACT compared with the baseline visit from 84.9±6.4 points (95% CI 81.9-87.9) to 75.7 ±6.7 points (95% CI 72.3-79.0) (p = 0.0001). Conclusions: The use of an enterosorbent as an accompanying therapy in CRC patients receiving ACT can significantly reduce the manifestation of chemotherapy toxicity and improve the quality of life of patients.

No abstract