More aggressive bone marrow screening in retinoblastoma patients is not indicated: the memorial Sloan-Kettering cancer center experience

Preclinical platform of retinoblastoma xenografts recapitulating human disease and molecular markers of dissemination

Translational research in retinoblastoma - a pediatric tumor that originates during the development of the retina - would be improved by the creation of new patient-derived models. Using tumor samples from enucleated eyes we established a new battery of preclinical models that grow in vitro in serum-free medium and in vivo in immunodeficient mice. To examine whether the new xenografts recapitulate human disease and disseminate from the retina to the central nervous system, we evaluated their histology and the presence of molecular markers of dissemination that are used in the clinical setting to detect extraocular metastases. We evaluated GD2 synthase and CRX as such markers and generated a Taqman real-time quantitative PCR method to measure CRX mRNA for rapid, sensitive and specific quantification of local and metastatic tumor burden. This approach was able to detect 1 human retinoblastoma cell in 100.000 mouse brain cells. Our research adds novel preclinical tools for the discovery of new retinoblastoma treatments for clinical translation.

SIOP-PODC recommendations for graduated-intensity treatment of retinoblastoma in developing countries

Retinoblastoma remains incurable in many regions of the world. The major obstacles to cure are delayed diagnosis, poor treatment compliance, and lack of evidence-based recommendations for clinical management. Although enucleation is curative for intraocular disease, in developing countries retinoblastoma is often diagnosed after the disease has disseminated beyond the eye. A SIOP-PODC committee generated guidelines for the clinical management of retinoblastoma in developing countries and developed a classification system based on the resources available in those settings. Recommendations are provided for staging and treatment of unilateral and bilateral retinoblastoma and counseling of families for whom compliance is an issue.

Results of a Multicenter Prospective Study on the Postoperative Treatment of Unilateral Retinoblastoma After Primary Enucleation

Purpose

The objective of this prospective study was to assess overall survival and event-free survival in patients with intraocular unilateral retinoblastoma (Reese-Ellsworth group V) treated by primary enucleation with or without adjuvant therapy depending on histopathologic risk factors.

Patients and Methods

Patients (n = 123) were divided into three groups on the basis of risk factors for extraocular relapse and metastasis assessed on centralized histologic examination of enucleated eyes. Group 1 (n = 70) had minimal or no choroidal involvement and/or prelaminar or no optic nerve involvement and received no adjuvant therapy. Group 2 (n = 52) had massive choroidal involvement and/or intra- or retrolaminar optic nerve involvement and/or anterior segment involvement and received four courses of adjuvant chemotherapy. Group 3 (n = 1) had invasion of the surgical margin of the optic nerve and/or microscopic extrascleral involvement and received six courses of adjuvant chemotherapy with intrathecal thiotepa, consolidation chemotherapy, and autologous stem-cell rescue. Genetic testing was also performed.

Results

Median follow-up for the 123 patients was 71 months. No disease progression, relapse, or distant metastasis occurred during follow-up. No second malignancies occurred. This requires confirmation with longer follow-up. Secondary bilateralization occurred in two patients with identified RB1 germline mutation. Adjuvant chemotherapy was well tolerated, with limited toxicity. Molecular testing found constitutional RB1 gene mutations in only nine of 100 evaluated patients.

Conclusion

The survival rate of 100% was excellent, including 57% of patients who received no adjuvant therapy, suggesting that chemotherapy could be de-escalated in some patients, especially those with massive choroidal involvement.