<b><i>Background:</i></b> Ex vivo confocal microscopy using fusion mode and digital staining (EVCM) scans unfixed fresh tissue and produces rapidly digitally stained images of very similar quality to classical pathology. We investigated whether EVCM could represent an alternative to the standard histological examination of the pretherapeutic basal cell carcinoma (BCC) punch biopsies. <b><i>Objectives:</i></b> The objective of the study was to assess diagnostic accuracy of EVCM versus traditional histopathological examination for diagnosing and subtyping clinically suspicious lesions of BCC in 3-mm fresh and nonfixed punch biopsies. <b><i>Methods:</i></b> In this prospective monocentric observational study, patients with clinically suspected BCC were consecutively enrolled. Punch biopsies were imaged using EVCM and subsequently processed for standard histologic examination (gold standard). EVCM images were examined by a dermatopathologist blinded to clinical aspect of the lesion and histopathological results. Concordance between the EVCM and histology analysis was calculated with Cohen’s kappa (κ) statistic. <b><i>Results:</i></b> Sixty-six patients were recruited, and 106 biopsies were analyzed. EVCM correctly diagnosed 70/73 BCCs and 31/33 non-BCC lesions, corresponding to a sensitivity of 96% and a specificity of 94% (positive predictive value = 97%, negative predictive value = 91%). The EVCM assessment led to over-staging and under-staging of BCC subtypes in 5% and 11% of cases, respectively. It led to over-staging and under-staging of BCC depths in 5% and 15%, respectively. The kappa coefficient for concordance was 0.78 (95% confidence interval [CI]: 0.69–0.88) when considering BCC subtypes and 0.81 (95% CI: 0.72–0.90) when considering BCC depths. <b><i>Conclusions:</i></b> These results render EVCM as a promising option for “real-time” pretreatment evaluation of clinically suspected BCC lesions. Further larger randomized studies are needed to assess the efficiency of EVCM versus standard care in patients with clinically suspected BCC.

490 Background: Evaluation of Patient-Reported Outcomes (PROs) is a major element used by health authorities for treatment approval. Pembrolizumab is a validated second-line treatment for locally advanced or metastatic urothelial carcinoma (la/mUC). In this real-life study, we aimed to describe la/mUC patients’ health-related quality of life (HRQoL) and patient/clinician-reported symptoms before and after pembrolizumab initiation. Here, we present interim results to assess clinical relevance for further analysis. Methods: A multicenter prospective French study was designed. PROs were assessed before pembrolizumab initiation (baseline) and at each treatment visit for seven timepoints. We report the analyses of the first three timepoints. HRQoL was measured using the European Organization for Research and Treatment of Cancer Quality-of-life Questionnaire-Core 30 (EORTC QLQ-C30) and the EuroQoL 5-dimensions 5-level (EQ-5D-5L) questionnaires. PRO-Common Terminology Criteria for Adverse Events (PRO-CTCAE) and CTCAE were assessed for 20 selected symptoms by both patients and clinicians in a blinded manner. Agreement in severity between clinicians and patients for all grade ≥3 symptoms was calculated with Cohen's kappa coefficient. Results: 39 patients were analyzed. Baseline completion rates were 69%, 62%, 59% and 12.8% for EORTC QLQ-C30, EQ-5D-5L, PRO-CTCAE and CTCAE respectively. Baseline median EORTC QLQ-C30 global health and summary scores were respectively 66.7 [interquartile range; 54.2, 79.2] and 83.6 [73.9, 94]. Improvement in EORTC QLQ-C30 global health median score to cycle 2 was observed in 33.3% patients, while the remaining patients experienced worsening score. Baseline mean EQ-5D-5L Visual Analog Scale score was 65.3 (Standard deviation (SD), 21.6), and 63.5 (SD, 16.1) at cycle 2. EQ-5D-5L domains scored level 1 decreased between baseline and cycle 2 for mobility (16 vs 14 patients) (p=0.0143), self-care (16 vs 14 patients) (p=0.0048), and usual activities (15 vs 14 patients) (p=0.015). Of 17 severity assessed symptoms, the Cohen's kappa coefficient was fair ĸ=0.35 (95% confidence interval (CI) [-0.08; 0.78]) for general pain, and bad ĸ=-0.063 (95%CI [-0.17; -0, 04]) for abdominal pain. In terms of symptom frequency, patients reported 19 symptoms at each visit. However, clinicians reported 13 and 14 symptoms respectively at baseline and cycle 2. Conclusions: HRQoL for la/mUC patients after first pembrolizumab infusion showed contradictory results with previous reports with a trend for HRQoL degradation after one treatment cycle. Comparative symptom severity assessment showed poor agreement between patients and clinicians. Clinicians graded symptoms less severely than patients. The final analysis will provide more complete data with longitudinal analysis to strengthen our preliminary conclusions. Clinical trial information: NCT03584659 .