Utility of bone marrow examination in retinoblastoma and their correlation with hematological features.

Retinoblastoma makes up about 3% of all childhood malignancies. The frequency of metastatic retinoblastoma ranges from 4.8 to 11%. Assessing the bone marrow status of newly diagnosed patients is crucial because of the advantages of autologous bone marrow transplants for high-risk patients. This study aimed to determine the utility of bone marrow examination in cases of retinoblastoma and its correlation with hematological findings. This retrospective study was conducted at the Department of Pathology, King George's Medical University, Lucknow, India. A total of 34 cases of retinoblastoma with bone marrow examination were included in the study. Bone marrow infiltration was present in 17.65% (6/34) cases of retinoblastoma. Bone marrow aspirate myelogram showed that marrow metastasis in retinoblastoma was significantly linked with a reduced percentage of total myeloid cells (p=0.001) and segmented cells (p=0.006). The present study demonstrated that 15% (3/20) of retinoblastoma patients previously classified as nonmetastatic before bone marrow examination (stages I to III based on histology, imaging, and bone scan) had bone marrow metastases following bone marrow examination and were upgraded to stage IV. To conclude, a diligent and exhaustive search for metastatic cells in bone marrow is advised if the myelogram shows a reduced percentage of total myeloid and segmented cells. All stage II and stage III cases of retinoblastoma must undergo bone marrow examination for early metastasis detection, as it may result in an upgrade to stage IV disease, impacting the prognosis and necessitating distinct treatment modalities.

RB/E2F1 as a Master Regulator of Cancer Cell Metabolism in Advanced Disease.

Loss of the retinoblastoma (RB) tumor suppressor protein is a critical step in reprogramming biological networks that drive cancer progression, although mechanistic insight has been largely limited to the impact of RB loss on cell-cycle regulation. Here, isogenic modeling of RB loss identified disease stage-specific rewiring of E2F1 function, providing the first-in-field mapping of the E2F1 cistrome and transcriptome after RB loss across disease progression. Biochemical and functional assessment using both in vitro and in vivo models identified an unexpected, prominent role for E2F1 in regulation of redox metabolism after RB loss, driving an increase in the synthesis of the antioxidant glutathione, specific to advanced disease. These E2F1-dependent events resulted in protection from reactive oxygen species in response to therapeutic intervention. On balance, these findings reveal novel pathways through which RB loss promotes cancer progression and highlight potentially new nodes of intervention for treating RB-deficient cancers. SIGNIFICANCE: This study identifies stage-specific consequences of RB loss across cancer progression that have a direct impact on tumor response to clinically utilized therapeutics. The study herein is the first to investigate the effect of RB loss on global metabolic regulation and link RB/E2F1 to redox control in multiple advanced diseases.This article is highlighted in the In This Issue feature, p. 2113.

Characteristics and Survival Outcomes of Second Primary Cancers in Long-term Retinoblastoma Survivors.

PURPOSE: Retinoblastoma (RB) is the most common intraocular cancer and is associated with lifelong risks of developing a second primary cancer, especially in patients with hereditary RB and/or childhood exposure to radiotherapy. METHODS: The study included all consecutive patients with a history of RB treated for a second primary cancer during 1994-2018. Patient demographics and characteristics of the primary RB and second primary cancer were examined. The associations among radiation or chemotherapy exposure as a treatment for RB, unilateral versus bilateral status, types and multiplicity of second primary cancers, and survival after diagnosis of second primary cancer were analyzed. RESULTS: A wide spectrum of second primary cancer types was identified from 62 eligible patients (30 males and 32 females), including sarcoma, breast cancer, various skin cancers, gastrointestinal and genitourinary cancers, and endocrine cancers. Of all patients who had second primary cancers, 40 patients (65%) had bilateral RB and 17 patients (27%) had unilateral RB. Thirty-five patients (56%) who developed second primary cancers received radiation therapy during childhood as the treatment of RB, and 17 patients (27%) received chemotherapy for the treatment of RB. The 5-year and 10-year survival rates for RB patients diagnosed with a second primary cancer were 54.0% and 36.0%, respectively. The median age of onset of second primary cancer among RB survivors was 36.6 years. CONCLUSIONS: In contrast to previous studies, we found a broader spectrum of second primary cancer types. All RB survivors, regardless of unilateral or bilateral status, should undergo strict cancer surveillance particularly as they approach the fourth decade of life.

Distantly Metastatic Retinoblastoma to Soft Tissue and Bone: A Challenging Diagnosis Highlighting the Utility of CRX.

Distant metastasis of retinoblastoma to sites outside the central nervous system is rare; such cases may present years following primary treatment. Diagnosis may be difficult given the rarity of such events and considerable histologic mimics. We describe the clinicopathologic features of 6 cases of metastatic retinoblastoma to distant bone and soft tissue sites from 2 large academic centers. Patients were 3 female and 3 male children; median age was 9.5 years (range: 5 to 15 y) with a mean interval from primary disease diagnosis of 8.0 years (range: 0.75 to 14 y). Metastasis to bones of the lower extremities was most common, occurring in 4 of 6 cases. Tumors showed typical histologic features of retinoblastoma, with sheets of primitive round cells with minimal cytoplasm and indistinct nucleoli; however, characteristic Flexner-Wintersteiner rosettes were absent. A subset of cases demonstrated an alveolar growth pattern, and 2 cases showed higher grade cytology with nuclear anaplasia and prominent nucleoli. Immunohistochemistry for CRX and RB1 showed uniform positivity and loss of expression, respectively. Metastatic retinoblastoma outside the central nervous system may present following long disease-free intervals. Immunohistochemistry for CRX is helpful to confirm this challenging diagnosis.

A Multicenter, International Collaborative Study for American Joint Committee on Cancer Staging of Retinoblastoma: Part I: Metastasis-Associated Mortality.

PURPOSE: To evaluate the ability of the 8th edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual to estimate metastatic and mortality rates for children with retinoblastoma (RB). DESIGN: International, multicenter, registry-based retrospective case series. PARTICIPANTS: A total of 2190 patients from 18 ophthalmic oncology centers from 13 countries over 6 continents. METHODS: Patient-specific data fields for RB were designed and selected by subcommittee. All patients with RB with adequate records to allow tumor staging by the AJCC criteria and follow-up for metastatic disease were studied. MAIN OUTCOME MEASURES: Metastasis-related 5- and 10-year survival data after initial tumor staging were estimated with the Kaplan-Meier method depending on AJCC clinical (cTNM) and pathological (pTNM) tumor, node, metastasis category and age, tumor laterality, and presence of heritable trait. RESULTS: Of 2190 patients, the records of 2085 patients (95.2%) with 2905 eyes were complete. The median age at diagnosis was 17.0 months. A total of 1260 patients (65.4%) had unilateral RB. Among the 2085 patients, tumor categories were cT1a in 55 (2.6%), cT1b in 168 (8.1%), cT2a in 197 (9.4%), cT2b in 812 (38.9%), cT3 in 835 (40.0%), and cT4 in 18 (0.9%). Of these, 1397 eyes in 1353 patients (48.1%) were treated with enucleation. A total of 109 patients (5.2%) developed metastases and died. The median time (n = 92) from diagnosis to metastasis was 9.50 months. The 5-year Kaplan-Meier cumulative survival estimates by clinical tumor categories were 100% for category cT1a, 98% (95% confidence interval [CI], 97-99) for cT1b and cT2a, 96% (95% CI, 95-97) for cT2b, 89% (95% CI, 88-90) for cT3 tumors, and 45% (95% CI, 31-59) for cT4 tumors. Risk of metastasis increased with increasing cT (and pT) category (P < 0.001). Cox proportional hazards regression analysis confirmed a higher risk of metastasis in category cT3 (hazard rate [HR], 8.09; 95% CI, 2.55-25.70; P < 0.001) and cT4 (HR, 48.55; 95% CI, 12.86-183.27; P < 0.001) compared with category cT1. Age, tumor laterality, and presence of heritable traits did not influence the incidence of metastatic disease. CONCLUSIONS: Multicenter, international, internet-based data sharing facilitated analysis of the 8th edition AJCC RB Staging System for metastasis-related mortality and offered a proof of concept yielding quantitative, predictive estimates per category in a large, real-life, heterogeneous patient population with RB.

Characterization of NCC-RbC-51, an RB cell line isolated from a metastatic site.

Retinoblastoma (RB) is a childhood eye tumor, caused by the RB1 gene mutation. Since RB is a rapidly proliferating tumor, the patient presents with a Group-D/E tumor at the time of diagnosis. Enucleation is preferred in most unilateral cases to prevent metastasis. Various cell lines have been established to study the tumor's growth pattern and target the cancer cells. The commonly used cell lines are WERI-Rb-1 and Y79, both isolated from the primary tumor of RB. Cell lines established from the metastatic site of RB have not been characterized before. In this study, we have characterized NCC-RbC-51, derived from RB tumor to cervical lymph node site and investigated its potential to represent a highly aggressive and metastatic tumor. We compared the proliferative and invasive properties of NCC-RbC-51 with a cell line isolated from the primary site, WERI-Rb-1. NCC-RbC-51 had higher rates of proliferation and apoptosis and had better invasive ability. Copy number variation analysis and the pathways predicted from these show that the pathways altered in NCC-RbC-51 could contribute to its metastatic nature. In all, the results suggest that NCC-RbC-51, a cell line isolated from metastatic site, could be a potential model to study aggressive/invasive RB.

Study of Unilateral Retinoblastoma With and Without Histopathologic High-Risk Features and the Role of Adjuvant Chemotherapy: A Children's Oncology Group Study.

PURPOSE: To prospectively determine the prevalence of high-risk histopathologic features (HRFs) in patients with unilateral retinoblastoma who undergo enucleation and to evaluate the role of chemotherapy in preventing recurrences. PATIENTS AND METHODS: Children newly diagnosed with enucleated unilateral retinoblastoma were enrolled prospectively. After central histopathology review, patients with specific HRFs received chemotherapy; others were observed. Primary end points were event-free survivals (EFS). RESULTS: Of the 331 patients enrolled during 2005 to 2010, 321 eligible patients had central histopathologic review. Discordance between central review and contributing institutions occurred in 23% of patients with HRFs and in 17% of patients without HRFs. Postlaminar optic nerve involvement was present in 53 patients; 42 had massive posterior uveal invasion (≥ 3 mm); 15 had concomitant peripapillary 3 mm or greater choroid and postlaminar optic nerve involvement; and 15 had focal (< 3 mm) choroidal concomitant with lamina or prelamina optic nerve involvement. Two-year EFS for patients with HRFs requiring adjuvant chemotherapy was 0.96 (95% CI, 0.89 to 0.98), and 2-year EFS for patients without HRFs for which observation was indicated was 0.99 (95% CI, 0.96 to 1.0). The 2-year EFS for all patients was 0.98 (95% CI, 0.96 to 0.99). CONCLUSION: Adequate handling and interpretation of histopathology of eyes with retinoblastoma is necessary to assign metastatic risk. Concomitant less than 3 mm choroidal and any prelaminar/laminar optic nerve invasion show no recurrence and may warrant no adjuvant chemotherapy. In contrast, concomitant greater than 3 mm peripapillary choroidal invasion and 1.5 mm or greater of postlaminar optic nerve invasion have the poorest outcomes, supporting the need for a more intensive adjuvant chemotherapy regimen for this subgroup. Strict criteria for adjuvant therapy may improve outcomes of children who undergo enucleation at diagnosis and may avoid unnecessary adjuvant chemotherapy for those who are not at risk for recurrence.

Conservative management of retinoblastoma: Challenging orthodoxy without compromising the state of metastatic grace. "Alive, with good vision and no comorbidity".

Retinoblastoma is lethal by metastasis if left untreated, so the primary goal of therapy is to preserve life, with ocular survival, visual preservation and quality of life as secondary aims. Historically, enucleation was the first successful therapeutic approach to decrease mortality, followed over 100 years ago by the first eye salvage attempts with radiotherapy. This led to the empiric delineation of a window for conservative management subject to a "state of metastatic grace" never to be violated. Over the last two decades, conservative management of retinoblastoma witnessed an impressive acceleration of improvements, culminating in two major paradigm shifts in therapeutic strategy. Firstly, the introduction of systemic chemotherapy and focal treatments in the late 1990s enabled radiotherapy to be progressively abandoned. Around 10 years later, the advent of chemotherapy in situ, with the capitalization of new routes of targeted drug delivery, namely intra-arterial, intravitreal and now intracameral injections, allowed significant increase in eye preservation rate, definitive eradication of radiotherapy and reduction of systemic chemotherapy. Here we intend to review the relevant knowledge susceptible to improve the conservative management of retinoblastoma in compliance with the "state of metastatic grace", with particular attention to (i) reviewing how new imaging modalities impact the frontiers of conservative management, (ii) dissecting retinoblastoma genesis, growth patterns, and intraocular routes of tumor propagation, (iii) assessing major therapeutic changes and trends, (iv) proposing a classification of relapsing retinoblastoma, (v) examining treatable/preventable disease-related or treatment-induced complications, and (vi) appraising new therapeutic targets and concepts, as well as liquid biopsy potentiality.

Combined high-dose intra-arterial and intrathecal chemotherapy for the treatment of a case of extraocular retinoblastoma.

Patients with retinoblastoma and central nervous system (CNS) involvement are rarely curable with available treatments. We designed a high-dose intra-arterial regimen targeting the ophthalmic artery and chiasm combined with intrathecal chemotherapy to treat a 4-year-old patient with retinoblastoma metastasized to the CNS. After three cycles of this regimen, including carboplatin, melphalan, and intrathecal topotecan, a partial response of the orbital tumor mass and chiasmatic lesion, and complete response in the cerebrospinal fluid and bone marrow were achieved. This new treatment strategy may be explored as a treatment component for patients with overt extraocular retinoblastoma and CNS dissemination.

PHOX2B is a reliable immunomarker in distinguishing peripheral neuroblastic tumours from CNS embryonal tumours.

AIMS: The PHOX2B gene regulates neuronal maturation in the brain stem nuclei associated with cardiorespiratory function and in the autonomic sympathetic and enteric nervous system. PHOX2B expression is a reliable immunomarker for peripheral neuroblastic tumours; however, no systematic evaluation of central nervous system (CNS) embryonal tumours was included in the studies. We encountered two cases in which the differential diagnosis included neuroblastoma and CNS embryonal tumour, and we hypothesised that PHOX2B immunostain would be helpful in establishing the diagnosis. METHODS AND RESULTS: PHOX2B immunostain was performed on 29 paediatric cases, with adequate controls: one retroperitoneal embryonal tumour in a child with retinoblastoma (index 1), one posterior fossa embryonal tumour in a child with a neuroblastoma (index 2), seven medulloblastomas, four atypical teratoid/rhabdoid tumours (ATRT), four retinoblastomas, six pineoblastomas, four embryonal tumours with multilayered rosettes (ETMR) and two CNS embryonal tumours, not elsewhere classified. Cell lineage immunomarkers (GFAP, OLIG2, synaptophysin, NeuN, CRX, PGP 9.5), immunosurrogates for molecular alterations (beta-catenin, INI1, Lin-28), array CGH and OncoPanel were performed as needed. Medulloblastomas, ATRTs, ETMRs, retinoblastomas and CNS embryonal tumours not elsewhere classified were essentially negative for PHOX2B. Two of six pineoblastomas had significant PHOX2B expression, while the rest were negative. Index 1 was negative for PHOX2B and PGP 9.5 and positive for CRX, consistent with retinoblastoma. Index 2 had diffuse PHOX2B expression, MYCN amplification and no copy number changes of medulloblastoma, in keeping with neuroblastoma. CONCLUSION: PHOX2B antibody is helpful in distinguishing between peripheral neuroblastic and CNS embryonal tumours, which are immunonegative, with the caveat that a subset of pineoblastomas has significant expression.

Retinoblastoma and optic nerve enhancement in a brain magnetic resonance scan: is it always a metastasis? / Retinoblastoma y realce del nervio óptico en la resonancia magnética cerebral: ¿es siempre una metástasis?

CASE REPORT: The case is presented on a girl with a unilateral retinoblastoma that required treatment with intra-arterial chemotherapy. In the nuclear magnetic resonance imaging of the brain performed 1 month after intra-arterial chemotherapy treatment, post-laminar optic nerve (ON) enhancement was observed, leading to the suspicion of an ON tumour infiltration. Additional examinations were requested by which a probable optic neuropathy was diagnosed. DISCUSSION: The ON enhancement in magnetic resonance imaging of the brain in retinoblastoma generally corresponds to tumour invasion of the ON. However, other diagnostic alternatives associated with the use of new treatments, such as intra-arterial chemotherapy, should be considered.

Successful conservative treatment of massive choroidal relapse in 2 retinoblastoma patients monitored by ultrasound biomicroscopy and/or spectral domain optic coherence tomography.

PURPOSE: To report the occurrence and management of secondary choroidal infiltration in two retinoblastoma (rb) patients. METHODS: Fundus examination and imaging with spectral domain optical coherence tomography (SD-OCT), B-scan ultrasonography (B-scan), and ultrasound biomicroscopy (UBM). RESULTS: Case 1: A 19-month-old girl with multifocal unilateral group B rb pretreated with intravenous chemotherapy (IVC) was referred for further management. At 3.5 years of age, routine 3-Tesla magnetic resonance imaging (3T-MRI) revealed an asymptomatic pinealoblastoma that underwent resection and adjuvant intensive IVC. Concomitant ophthalmic follow-up revealed a recurrence 8.3 × 2.8 mm at the posterior pole nasally to the optic disc on B-scan, localized within the choroid on SD-OCT and 3T-MRI. With high dose IVC ongoing, total regression of the choroidal mass was confirmed on SD-OCT already after 3 weeks. At 6-month follow-up, choroidal and pineal tumors were in complete remission. Sadly, the child died of intravascular disseminated coagulation-like disease after the 5th IVC. Case 2: A heavily pretreated 20-month-old girl with bilateral rb was referred for persistent vitreous seeding in her remaining eye (OD). Three months after intravitreal chemotherapy and chemothermotherapy, a hemorrhagic mass was observed inferior to the primary tumor. Two weeks later, an underlying peripheral choroidal mass 16 × 6 mm was documented by UBM and confirmed by 3T-MRI. Complete resolution was achieved 3 weeks after combined intra-arterial chemotherapy (IAC) of melphalan-topotecan. No recurrence or metastasis was observed at 34-month follow-up. CONCLUSION: Isolated massive choroidal invasion can be treated conservatively with IVC or IAC in selected cases. SD-OCT, UBM, and B-scan ultrasonography are instrumental in the detection and follow-up of choroidal lesions.

Risk of Extraocular Extension in Eyes With Retinoblastoma Receiving Intravitreous Chemotherapy.

Importance: The risk of extraocular extension from injecting chemotherapy into eyes with retinoblastoma is minimally understood; however, understanding this risk is important because of the increasing use of intravitreous chemotherapy. Objective: To evaluate the risk of extraocular extension in eyes with retinoblastoma that have received intravitreous chemotherapy injections. Design, Setting, and Participants: This retrospective cohort study was performed in 655 patients at 10 retinoblastoma centers in North and South American, European, Israeli, and Chinese centers. Physicians at the retinoblastoma centers administered more than 120 intravitreous chemotherapy injections in eyes with retinoblastoma from February 1, 1999, through February 28, 2017. Main Outcomes and Measures: Risk of extraocular extension with secondary observational variables, including injection and precautionary techniques. Results: A total of 3553 intravitreous chemotherapy injections (3201 melphalan hydrochloride, 335 topotecan hydrochloride, and 17 methotrexate sodium) were administered to 704 eyes in 655 patients with retinoblastoma (mean [SD] age of patients at the time of the initial injections, 31.6 [11.6] months; 348 male [53.1%]). There were no extraocular tumor events related to prior intravitreous injections. This finding resulted in a calculated proportion of zero extraocular events per eye. According to the rule of 3, the risk is no greater than 0.08% injections. All 10 centers included in this study used at least 2 presumed precautionary injection methods (lowering of intraocular pressure, cryotherapy, ocular surface irrigation, ultrasonic biomicroscopy surveillance of the injection site, and subconjunctival chemotherapy deposition). Conclusions and Relevance: With use of at least 2 presumed precautionary safety methods, no extraocular extension of tumor events occurred. According to the rule of 3, this finding suggests that the risk is no greater than 0.08% injections.

[Clinical features, treatment and prognosis of retinoblastoma in distant metastasis stage].

Objective: To summarize the clinical features, treatment and prognosis of retinoblastoma (RB) patients in distant metastasis stage. Methods: Retrospective case series study. Clinical data of 24 cases (30 eyes) with diagnosis of distant metastasis stage RB were collected in pediatrics department of Beijing Tongren Hospital affiliated with Capital Medical University, from September 2005 to December 2013. In these cases, including 11 male cases and 13 female cases, the treatment age ranged from 7 months to 9 years with the median of 26 months. There were 18 unilateral cases (12 cases of right eye and 6 cases of left eye) and 6 bilateral cases. All cases were treated with surgery, chemotherapy and radiotherapy. The adverse reaction, blood routine and biochemical routine were monitored dynamically and regularly during treatment. The clinical manifestations and auxiliary examination were combined to evaluate the therapeutic effect. Determining the prognosis with death and survival, the survival curve and the median survival time were calculated by the product limit method. Results: The results of pathologic examination of 13 cases showed 11 cases of optic nerve involvement, 6 cases of optic nerve and choroid involvement, 1 case of post laminar involvement, 1 case of cornea and conjunctiva involvement. The most common metastatic site was central nerve system (CNS) (23 cases), followed by orbital involvement (10 cases). Other metastatic sites included bone (9 cases), bone marrow (1 case), pleura (1 case) and lymph node (1 case). 23 patients with CNS metastasis underwent systemic chemotherapy and intrathecal injection. The toxicity and side effects of radiotherapy and chemotherapy were evaluated and classified as grade I-II. Those adverse effects were tolerated by all cases. Followed up to December 31, 2015, all patients with CNS metastasis died and the median survival time was 6 months. Only 1 patient without CNS metastasis disease-free survived for 64 months. Conclusions: The most common metastasis site of RB was CNS. The overall prognosis of RB with distant metastasis was poor, in spite of given combined treatment mainly including surgery, chemotherapy and radiotherapy. But the prognosis of RB patients without CNS metastasis in distant metastasis stage was better than with CNS metastasis. (Chin J Ophthalmol, 2017, 53: 121-126).

Intraocular Pressure Changes Following Intravitreal Melphalan and Topotecan for the Treatment of Retinoblastoma With Vitreous Seeding.

PURPOSE: To investigate the impact of intravitreal chemotherapy on intraocular pressure (IOP) in children with retinoblastoma. METHODS: This was a retrospective study of 10 eyes of 10 patients with retinoblastoma (7 males, 3 females, mean age: 33.6 ± 9.4 months) with vitreous seeding injected with intravitreal melphalan and topotecan. IOP was measured with Tonopen (Reichert, Inc., Buffalo, NY) at baseline prior to injecting and then repeatedly following each intravitreal injection. RESULTS: Mean pre-injection IOP was 8.2 ± 2.3 mm Hg (range: 4 to 12 mm Hg). Mean IOP 1 to 30 seconds after intravitreal melphalan (first injection) was 45.4 ± 14.3 mm Hg. The IOP of 89.5% of patients declined to 29 mm Hg or less in a mean 153.3 ± 97.5 seconds. Mean IOP 1 to 30 seconds after intravitreal topotecan (second injection) was 44.5 ± 11.0 mm Hg, which decreased to 31.0 ± 5.0 mm Hg by 150 seconds after injection. No significant relationship was found between age and post-injection IOP elevation. IOP exceeded the calculated mean arterial perfusion pressure in four encounters. CONCLUSIONS: Intravitreal chemotherapy caused a transient rise in IOP. Post-injection IOP elevations can reach levels that may exceed mean arterial pressure. [J Pediatr Ophthalmol Strabismus. 2017;54(3):185-190.].

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.