Immunohistochemical expression of TFF1 is a new prognostic marker in retinoblastoma

Introduction The risk of relapse in retinoblastoma is currently determined by the presence of high-risk histopathologic factors in the enucleated eye. However, the probability of developing metastatic disease is heterogeneous among these patients. Evaluating a biological marker to identify high-risk patients could be useful in clinical setting. This study aims to evaluate whether the expression of TFF1, a surrogate for subtype 2 retinoblastoma, is a prognostic marker for relapse and death. Methods This multicenter cohort study included 273 patients, 48 of whom had extraocular disease. Immunohistochemical staining were performed for CRX, ARR3, TFF1 and Ki67. Tumors were classified as histological subtype 1 (HS1) if they had low or no expression of TFF1 (quick score (QS) ≤ 50) and as histological subtype 2 (HS2) if they expressed TFF1 diffusely (QS > 50). We studied the association between HS classification and outcome. Results Of 273 patients, 35.9% were classified as HS1, 59.3% as HS2 and 4.8% were not evaluable. In multivariate analysis, patients with HS2 tumors had a higher probability of relapse and death than those with HS1 ( P < 0.0001 and P = 0.00020, respectively). We identified a higher-risk subgroup among HS2 tumors, presenting non-mutually exclusive expression of ARR3 and TFF1 and had an increased risk of relapse and death compared to tumors that displayed mutually exclusive expression ( P = 0.012 and P = 0.027, respectively). Conclusions Expression of TFF1, especially when it is not-mutually exclusive with ARR3, is an independent prognostic marker of poor outcome in retinoblastoma. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This research was funded by the Agencia Nacional de Promocion Cientifica y Tecnologica (Buenos Aires, Argentina) (PIDC 2014-0043); Fondation Nelia et Amadeo Barletta (Nyon, Switzerland); Ligue Nationale Contre le Cancer and Retinostop (Paris, France); Fundacion Leo Messi (Barcelona, Spain); Fund for Ophthalmic Knowledge (New York, United States of America) Instituto Nacional del Cancer (Buenos Aires, Argentina); Fundacion Natali Dafne Flexer de Ayuda al Nino con Cancer (Buenos Aires, Argentina); Fundacion Garrahan (Buenos Aires, Argentina) and Instituto Oncologico Henry Moore (Buenos Aires, Argentina). The sponsors or funding organizations had no role in the design or conduct of this research. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Hospital de Pediatria Garrahan Institutional Review Board gave ethical approval for this work (Protocol #979). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present work are contained in the manuscript * ARR3 : Arrestin-C CI : Confidence interval CNA : Copy number alterations CNS : Central nervous system CRX : Cone-rod homeobox EFS : Event-free survival HPG : Hospital de Pediatría JP Garrahan HR : Hazard ratio HRPF : High-risk pathology factors HS1 : Histological subtype 1 HS2 : Histological subtype 2 INCA : Instituto Nacional de Cáncer IRSS : International retinoblastoma stage system MSKCC : Memorial Sloan Kettering Cancer Center OS : Overall survival QS : Quick score SJD : Hospital Sant Joan de Déu TFF1 : Trefoil factor 1