GÉTICA 2021

7 [ F I T C á n c e r - 7 ] full-length sequences). The following metrics were measured: observed OTUs (community richness), evenness (Pielou’s index) and Shan- non’s diversity index. Differential abundance of taxa was tested using ANCOM test and Kruskal Wallis test. Results: A total of 21 patients have been treated with TILs between 2018 and 2020 at our institution. 67 % were female. Median age was 43 (range 26-70 years). All patients had stage IV pre-treated solid tumours: 55 % cer- vical cancer, 33 % melanoma, 10 % lung ade- nocarcinoma, and 5 % head and neck cancer. Median previous treatment lines were 3 (range 2-4). Analysis of gut microbiome has been per- formed in 3 of these patients: one achieved PR, one progressed and the third one suffered an unexpected death. 971 phylotypes were detected. Analysis revealed differences in terms of observed OTUs, evenness and Shan- non’s index when comparing T1 and T2 with T3. At T3 a tendency towards less diversity and evenness was observed when compared with T1 and T2 (H 3.0, p-value 0.083, not sta- tistically significant). Comparing the distribu- [ F I T C á n c e r - 7 ] CC01 . ANALYSIS OF GUT MICROBIOME IN PATIENTS RECEIVING ADOPTIVE T-CELL THERAPY (ACT) ACROSS DIFFERENT SOLID TUMOUR TYPES Barquin García, Arantzazu; Ruiz Llorente, Sergio; Navarro Alcaraz, Paloma; Rodríguez Moreno, Juan Francisco; Sevillano Fernández, Elena; Yagüe Fernández, Mónica; Amarilla Quintana, Sandra; Serrano del Hoyo, Sandra; Fox, Bárbara; Quiralte, Miguel; Barba Llácer, María; Fernández Santiago, Cristóbal; García-Donas, Jesús Hospital Universitario HM Sanchinarro. Centro Integral Oncológico Clara Campal (CIOCC). Madrid Background: Tumour infiltrating lympho- cytes (TILs) is a modality of ACT under devel- opment in solid tumours. Unfortunately, prior lymphodep letion is a key step that frequently requires the administration of antibiotics and anti-fungics for long periods of time. Although there is evi- dence that gut microbiome may influence tu- mour response in patients treated with check- point-inhibitors, it has not been extensively studied in ACT. Methods: Analysis of gut microbiome at three different times (T1: before lympho- depletion, T2: before TIL infusion and T3: day +15) has been performed in patients treated with ACT between 2018 and 2020. The com- position and structure of the sampled micro- bial communities was assessed through the amplification and sequencing the V3-V4 varia- ble regions of the 16S rRNA gene. The Illumina Miseq sequencing 300×2 approach was used. Taxonomic assignment of phylotypes was performed using a Bayesian Classifier trained with Silva database version 132 (99 % OTUs COMUNICACIONES CORTAS