Association of Cone-Rod Homeobox Transcription Factor Messenger RNA With Pediatric Metastatic Retinoblastoma.
OBJECTIVE
Disseminated retinoblastoma is usually fatal. Identification of small amounts (minimal dissemination [MD]) of tumor cells in extraocular sites might be a tool for designing appropriate treatments.


OBJECTIVE
To test cone-rod homeobox (CRX) transcription factor as a lineage-specific molecular marker for metastatic retinoblastoma and for evaluation of MD.


METHODS
In a prospective cohort design study, we evaluated CRX messenger RNA (mRNA) by retrotranscription followed by real-time polymerase chain reaction as a diagnostic test in samples obtained from bone marrow, peripheral blood, and cerebrospinal fluid (CSF) at diagnosis, after induction chemotherapy, and during follow-up. The study was conducted from June 30, 2008, to June 30, 2014. Seventeen retinoblastoma primary tumors, 2 retinoblastoma cell lines, and 47 samples of bone marrow from other cancers (controls) were studied. Seventeen patients with metastatic retinoblastoma (9 at diagnosis, 8 at relapse; age range: 18-41 months) were included.


METHODS
Detection of CRX mRNA as a marker for metastatic retinoblastoma 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 levels range, 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 marrow metastatic cells showed expression of CRX mRNA in all 9 children presenting with metastasis at the diagnosis (relative expression levels, 6.0 × 10-5 to 0.67). After induction chemotherapy, no evidence of MD of tumor cells was seen in any of the 8 responding children since only GAPDH showed amplification. In the CSF of children who had a metastatic relapse, CRX mRNA detection was positive in 2 patients in whom no conclusive results were reached by immunocytology for disialoganglioside GD2. Minimal dissemination in the CSF was associated with a clinical relapse in 2 cases. No concomitant MD was evident in the bone marrow in any case.


CONCLUSIONS
These data suggest that CRX mRNA is a novel marker for retinoblastoma at extraocular sites. In this study among patients with bone marrow metastasis, there was a quick, complete, and sustained molecular response after induction chemotherapy. In all patients with secondary metastasis, CSF relapse occurred independently from the bone marrow, suggesting a sanctuary site.
Hematology-Oncology Service, Pediatric Hospital, Servicios de Atención Médica Integral para la Comunidad, Professor Dr. Juan P. Garrahan, Buenos Aires, Argentina.
Ana V
AV
Torbidoni
Hematology-Oncology Service, Pediatric Hospital, Servicios de Atención Médica Integral para la Comunidad, Professor Dr. Juan P. Garrahan, Buenos Aires, Argentina.
Viviana E
VE
Laurent
Hematology-Oncology Service, Pediatric Hospital, Servicios de Atención Médica Integral para la Comunidad, Professor Dr. Juan P. Garrahan, Buenos Aires, Argentina.
Claudia
C
Sampor
Hematology-Oncology Service, Pediatric Hospital, Servicios de Atención Médica Integral para la Comunidad, Professor Dr. Juan P. Garrahan, Buenos Aires, Argentina.
Daniela
D
Ottaviani
Pathology Service, Pediatric Hospital Servicios de Atención Médica Integral para la Comunidad Professor Dr. Juan P. Garrahan, Buenos Aires, Argentina.
Valeria
V
Vazquez
Molecular Oncology Laboratory, Quilmes National University, Bernal, Argentina.
Mariano R
MR
Gabri
Immunology Service, Pediatric Hospital Servicios de Atención Médica Integral para la Comunidad Professor Dr. Juan P. Garrahan, Buenos Aires, Argentina.
Jorge
J
Rossi
Pathology Service, Pediatric Hospital Servicios de Atención Médica Integral para la Comunidad Professor Dr. Juan P. Garrahan, Buenos Aires, Argentina.
María T
MT
de Dávila
Hematology-Oncology Service, Pediatric Hospital, Servicios de Atención Médica Integral para la Comunidad, Professor Dr. Juan P. Garrahan, Buenos Aires, Argentina.
Cristina
C
Alonso
Molecular Oncology Laboratory, Quilmes National University, Bernal, Argentina.
Daniel F
DF
Alonso
Hematology-Oncology Service, Pediatric Hospital, Servicios de Atención Médica Integral para la Comunidad, Professor Dr. Juan P. Garrahan, Buenos Aires, Argentina.
Guillermo L
GL
Chantada
D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D015972:Gene Expression Regulation, Neoplastic; D020022:Genetic Predisposition to Disease / Q000453:epidemiology*; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D009361:Neoplasm Invasiveness / Q000473:pathology; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D011446:Prospective Studies; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D019572:Retinal Neoplasms / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology; D012175:Retinoblastoma / Q000453:epidemiology / Q000235:genetics* / Q000556:secondary; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics
D018398:Homeodomain Proteins; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; C109288:cone rod homeobox protein