Association of Cone-Rod Homeobox Transcription Factor Messenger RNA With Pediatric Metastatic Retinoblastoma

ANA VANESA TORBIDONI; VIVIANA LAURENT; OTTAVIANI DANIELA; SAMPOR CLAUDIA; VALERIA VAZQUEZ; GABRI MARIANO; JORGE ROSSI; ALONSO CRISTINA; GARCIA DE DAVILA MARIA TERESA; DANIEL F ALONSO; CHANTADA GUILLERMO

JAMA ophthalmology

Chicago, IL : American Medical Association

Año: 2015

2168-6165

IMPORTANCE Disseminated retinoblastoma is usually fatal. Identification of small amounts(minimal dissemination [MD]) of tumor cells in extraocular sites might be a tool for designingappropriate treatments.OBJECTIVE To test cone-rod homeobox (CRX) transcription factor as a lineage-specificmolecular marker formetastatic retinoblastoma and for evaluation of MD.DESIGN, SETTING, AND PARTICIPANTS In a prospective cohort design study,we evaluated CRXmessenger RNA (mRNA) by retrotranscription followed by real-time polymerase chainreaction as a diagnostic test in samples obtained from bone marrow, peripheral blood, andcerebrospinal fluid (CSF) at diagnosis, after induction chemotherapy, and during follow-up.The study was conducted from June 30, 2008, to June 30, 2014. Seventeen retinoblastomaprimary tumors, 2 retinoblastoma cell lines, and 47 samples of bone marrow from othercancers (controls) were studied. Seventeen patients with metastatic retinoblastoma (9 atdiagnosis, 8 at relapse; age range: 18-41 months) were included.MAIN OUTCOMES AND MEASURES Detection of CRX mRNA as a marker formetastaticretinoblastoma and MD in bone marrow and CSF and its correlation with clinical findings.RESULTS Cone-rod homeobox mRNA was expressed in all tumors (relative expression levelsrange, 8.1 × 10−5 to 5.6) and cell lines. In control samples, there was no amplification of CRX;only the housekeeping gene (GAPDH) demonstrated amplification. Bone marrowmetastaticcells showed expression of CRX mRNA in all 9 children presenting with metastasis at thediagnosis (relative expression levels, 6.0 × 10−5 to 0.67). After induction chemotherapy, noevidence of MD of tumor cells was seen in any of the 8 responding children since only GAPDHshowed amplification. In the CSF of children who had ametastatic relapse, CRX mRNAdetection was positive in 2 patients in whom no conclusive results were reached byimmunocytology for disialoganglioside GD2. Minimal dissemination in the CSF was associatedwith a clinical relapse in 2 cases. No concomitant MD was evident in the bone marrow inany case.CONCLUSIONS AND RELEVANCE These data suggest that CRX mRNA is a novel marker forretinoblastoma at extraocular sites. In this study among patients with bone marrowmetastasis, there was a quick, complete, and sustained molecular response after inductionchemotherapy. In all patients with secondarymetastasis, CSF relapse occurred independentlyfrom the bone marrow, suggesting a sanctuary site.