Background. In vivo comparison of cardiac radiofrequency ablation lesions between standard and magnetically steered 4 mm tip catheters has never been reported. Methods. High and low right atrium (RA) free wall, isthmus, right ventricle (RV) free wall and outflow tract lesions were studied macroscopically and microscopically five days after lesion formation in seven pigs. Shape, size, thrombus formation, and ablation parameters were compared. The effect of minimal, medium and high wall contact was assessed by a contact measurement utility for magnetic catheters. Results. All 14 RA free wall lesions were transmural with a similar epicardial and endocardial surface area. In the RV, the epicardial area usually appeared to be smaller than the endocardial area with standard catheters. Isthmus lesions were difficult to assess transmurality.

A 58-year-old female patient underwent an esthetic breast augmentation surgery in 2014 which 5 years later, led to edema, hyperemia and a volume increase of the left breast ( Figure 1). Initially diagnosed with mastitis she was prescribed oral nonsteroidal anti-inflammatory drugs and antibiotics for a period of 10 days, and after no improvement, the patient was admitted in hospital for intravenous antibiotics treatment. The admission ultrasound (US) uncovered a late seroma characterized by an intracapsular heterogeneous collection compressing the breast implant on the left breast (Figure 2). A magnetic resonance imaging (MRI) was performed for further investigation. The scan showed a late seroma, with a hydro-aerial level and progressive enhancement of the fibrous capsules especially on the left breast, as well as intracapsular masses with late contrast enhancement, "black drop sign" and pericapsular edema. The implants were intact at MRI. No extra capsular collections were observed (Figure 3).After being submitted to surgical intervention, in order to explantation and capsulectomy an intracapsular collection and a friable fibrous capsule with thickened areas were retrieved and sent to histologic analysis.

e21159 Background: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) are the standard therapy for EGFR-mutated non-small cell lung cancer (NSCLC) patients. Unfortunately, patients eventually develop resistance to EGFR-TKI and disease progression. Re-exposure after a drug-free interval may be an alternative to overcome tumor resistance. We performed a systematic review and meta-analysis to assess EGFR-TKI retreatment’s efficacy in advanced NSCLC. Methods: We systematically searched PubMed, Embase, and Cochrane databases for clinical trials and observational cohort studies evaluating EGFR-TKI retreatment in advanced NSCLC patients. We aimed to assess the objective response rate (ORR), disease control rate (DCR), and survival outcomes. Subgroup analyses were performed according to the type of EGFRmutation and the TKI drug used in retreatment. We further stratified studies to assess the efficacy of rechallenging with the same drug used initially or a different one. Heterogeneity was assessed using the Cochran Q test, and I2 statistics and random effects models were fitted. Results: We included 16 studies (7 prospective clinical trials, and 9 retrospective cohorts) with 806 patients. Most of them had adenocarcinoma (70.8%), were females (58.1%), and were non-smokers (74.5%). The most frequently TKI given as the initial treatment was gefitinib (58.1%), whereas in the rechallenge it was erlotinib (36.6%) followed by gefitinib (31.6%). In a pooled analysis of patients who were retreated with TKI, the median PFS was 4.1 months (95%CI 3.0 - 4.4), and OS was 12.6 months (95%CI 10.2 - 12.6). ORR was 16% (95%CI 10 - 22%) and DCR was documented in 63% (95%CI 0.54 - 0.72%). Patients harboring a sensitive EGFR mutation had a significantly higher DCR, compared to patients with EGFRT790M mutation, and those with unknown mutational status, (DCR: 70%, 62%, and 48%, respectively, p = 0.02). Patients rechallenged with gefitinib, erlotinib, or afatinib had a similar DCR of 60%, while patients re-exposed to osimertinib had a greater DCR of 70% (95%CI 59 - 80%), (p < 0.01). Regarding ORR, no significant difference was observed amongst the groups defined by the type of EGFR mutation (p = 0.74) or type of TKI used (p = 0.05). Rechallenge using the same versus a different TKI resulted in similar ORR and DCR. In a subgroup analysis of 102 patients who had disease control with the first TKI, 62% (95%CI 45 – 79%) achieved disease control with TKI rechallenge. Conclusions: Our meta-analysis suggests that a subgroup of advanced EGFR-mutated NSCLC patients who failed TKI treatment benefit from rechallenge with an EGFR-TKI after a TKI-free interval. Re-exposure with either the same or a different TKI was shown to be equally effective. Patients treated with osimertinib and those with EGFR-sensitive mutations have better responses to the treatment.

e17587 Background: PARP inhibitors (PARPi) have been approved for maintenance therapy in newly diagnosed ovarian cancer patients with or without homologous recombination deficiency (HRD). In this meta-analysis, the latest clinical data to assess the efficacy and safety of this approach across different subgroups were synthesized. Methods: PubMed, Scopus, and Cochrane databases were searched for randomized controlled trials that compared maintenance PARPi with placebo in newly diagnosed ovarian cancer. The outcomes of interest included progression-free survival (PFS) according to HRD status, overall survival (OS), second PFS (PFS2), and time-to-first subsequent treatment (TFST). Heterogeneity was examined with I2 statistics. A random-effects model was used for outcomes with high heterogeneity. Results: A total of 6 Randomized clinical trials with 3609 patients were included, of whom 2348 (65%) received maintenance PARPi. PFS was significantly longer for HRD-positive patients receiving PARPi [Hazard ratio (HR) 0.44, 95% Confidence interval (CI) 0.37 – 0.52 p<0.001] and for HRD-negative patients [HR 0.71, 95% CI 0.54 – 0.92 p=0.009]. Maintenance PARPi was associated with improved OS in HRD-positive patients [HR 0.59, CI 0.47 -0.73, p<0.001] but not in unselected patients. PFS2 in the HRD-positive population was reported in three trials, and it favored the use of PARPi [HR 0.57, CI 0.43 – 0.76, p<0.001]. Adverse events ≥grade 3 were more common in patients on maintenance PARPi (p<0.001). The occurrence of myelodysplastic syndrome was numerically but not significantly higher in the PARPi group. Conclusions: Maintenance with PARPi in patients with newly diagnosed ovarian cancer significantly prolongs PFS regardless of HRD status. Moreover, PARPi maintenance improves OS and PFS2 in patients with BRCA and/or HRD-positive tumors compared to placebo. [Table: see text]

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