Recent advances and challenges in the management of retinoblastoma

Pluripotent stem cell-derived models of retinal disease: Elucidating pathogenesis, evaluating novel treatments, and estimating toxicity

Blindness poses a growing global challenge, with approximately 26% of cases attributed to degenerative retinal diseases. While gene therapy, optogenetic tools, photosensitive switches, and retinal prostheses offer hope for vision restoration, these high-cost therapies will benefit few patients. Understanding retinal diseases is therefore key to advance effective treatments, requiring in vitro models replicating pathology and allowing quantitative assessments for drug discovery. Pluripotent stem cells (PSCs) provide a unique solution given their limitless supply and ability to differentiate into light-responsive retinal tissues encompassing all cell types. This review focuses on the history and current state of photoreceptor and retinal pigment epithelium (RPE) cell generation from PSCs. We explore the applications of this technology in disease modelling, experimental therapy testing, biomarker identification, and toxicity studies. We consider challenges in scalability, standardisation, and reproducibility, and stress the importance of incorporating vasculature and immune cells into retinal organoids. We advocate for high-throughput automation in data acquisition and analyses and underscore the value of advanced micro-physiological systems that fully capture the interactions between the neural retina, RPE, and choriocapillaris.

Treatment adherence in retinoblastoma: A retro-prospective cohort study in Ivory Coast and the Democratic Republic of Congo

BACKGROUND

In high-income countries, retinoblastoma is curable in more than 95% of cases, whereas in low-income countries, mortality remains high, especially when the diagnosis is made late or the treatment is discontinued.

AIMS

To determine the factors associated with adherence to the treatment of retinoblastoma in the Ivory Coast and the Democratic Republic of Congo (DRC).

METHODS AND RESULTS

A retro-prospective cohort study was carried out. Data were collected from patient folders and follow-up records of parents.

RESULTS

A total of 175 children with retinoblastoma were registered from January 2013 to December 2015. Seventy-six children (43%) were 5 years old and above. Care costs were covered by families in 86.9% of cases. Chemotherapy refusal was recorded in 39 cases (22.3%), and enucleation refusal was recorded in 79 cases (45.1%). After 36 months of follow-up, we recorded 16.6% deaths, 27.4% treatment dropouts, and 18.3% loss to follow-up after treatment. The commonest cause for enucleation refusal was fear of infirmity, while chemotherapy refusal and absconding treatment were due to financial constraints.

CONCLUSION

Poor adherence to retinoblastoma management was due to financial constraints, and a lack of knowledge of the disease and its treatment. Family psychosocial support is needed to improve this condition.

Retinoblastoma: A review of the molecular basis of tumor development and its clinical correlation in shaping future targeted treatment strategies

Retinoblastoma is a retinal cancer that affects children and is the most prevalent intraocular tumor worldwide. Despite tremendous breakthroughs in our understanding of the fundamental mechanisms that regulate progression of retinoblastoma, the development of targeted therapeutics for retinoblastoma has lagged. Our review highlights the current developments in the genetic, epigenetic, transcriptomic, and proteomic landscapes of retinoblastoma. We also discuss their clinical relevance and potential implications for future therapeutic development, with the aim to create a frontline multimodal therapy for retinoblastoma.

Identification of Epigenetically Modified Hub Genes and Altered Pathways Associated With Retinoblastoma

Retinoblastoma (Rb) is the most common childhood malignancy initiated by biallelic mutation in RB1 gene and driven by various epigenetic events including DNA methylation and microRNA dysregulation. Hence, understanding the key genes that are critically modulated by epigenetic modifications in RB1^−/− cells is very important to identify prominent biomarkers and therapeutic targets of Rb. In this study, we for the first time have integrated various Rb microarray NCBI-GEO datasets including DNA Methylation (GSE57362), miRNA (GSE7072) and mRNA (GSE110811) to comprehensively investigate the epigenetic consequences of RB loss in retinoblastoma tumors and identify genes with the potential to serve as early diagnostic markers and therapeutic targets for Rb. Interestingly, the GEO2R and co-expression network analysis have identified three genes namely E2F3, ESR1, and UNC5D that are significantly deregulated by modified DNA methylation, mRNA and microRNA expression in Rb tumors. Due to their recognition in all epigenetic, transcriptomic, and miRNA datasets, we have termed these genes as “common genes”. The results of our integrative bioinformatics analysis were validated in vitro by studying the gene and protein expression of these common genes in Y79, WERI-Rb-1, Rb cell lines and non-tumorigenic retinal pigment epithelial cell line (hTERT-RPE). The expression of E2F3 and UNC5D were up-regulated and that of ESR1 was down-regulated in Rb tumor cells when compared to that in non-tumorigenic hTERT-RPE cells. More importantly, UNC5D, a potent tumor suppressor gene in most cancers is significantly up-regulated in Y79 and Weri Rb1 cells, which, in turn, questions its anti-cancer properties. Together, our study shows that E2F3, ESR1, and UNC5D may be crucially involved in Rb tumorigenesis and possess the potential to act as early diagnostic biomarkers and therapeutic targets of Rb.

AN IN VIVO STUDY OF INTRAVITREAL RANIBIZUMAB FOLLOWING SUBRETINAL INOCULATION OF RB CELLS IN RABBITS EYES

AIM

This study aimed to determine the effects of a single intravitreal ranibizumab injection in rabbits induced with retinoblastoma (RB).

MATERIAL AND METHODS

RB was induced in six New Zealand white rabbits by subretinal injection of a cultured WERI-RBb-1 cell line into the right eye. After six weeks, Group A (n = 3) was given intravitreal ranibizumab injection (0.3mg in 0.03ml) and Group B (n = 3) was the control. Baseline and serial clinical examinations were performed on days 1, 3, 6, 12, 15, 18 and 21. The right eyes were enucleated for both groups on day 21 for histopathological examination.

RESULTS

The rabbits in both groups developed intraocular lesions which was detectable clinically at one-week post-tumor inoculation. The tumor grew slowly without spontaneous regression. After the animals in Group A were given an intravitreal ranibizumab injection, regression of the tumor was detected clinically, while the tumor in Group B continued to grow slowly. Histopathological findings confirmed the presence of a tumor that closely resembled features of poorly differentiated human RB cells. At the end of 21 days, the size of the tumor was larger in Group B in comparison to Group A. However, the treated group also developed a focal area of retinal hyperplasia. There was no significant side effect of ranibizumab injection except temporary high intraocular pressure immediately post-injection, which was relieved after paracentesis.

CONCLUSIONS

Intravitreal ranibizumab is a potential treatment for RB. It is an effective therapy with a tolerable safety profile in this animal experimental study.

Long non-coding RNA SND1-IT1 accelerates cell proliferation, invasion and migration via regulating miR-132-3p/SMAD2 axis in retinoblastoma

Long noncoding RNAs (lncRNAs) have been identified as prognostic biomarkers and functional regulators in human tumors. In our study, we aim to investigate the roles of lncRNA SND1-IT1 (SND1-IT1) in retinoblastoma (RB). We observed that SND1-IT1 was highly expressed in both RB specimens and cells, and associated with poorer prognosis of RB patients. Functional investigation revealed that downregulation of SND1-IT1 suppressed RB cell proliferation, migration and invasion in vitro and restrained RB tumorigenesis in vivo. MiR-132-3p was predicted to interact with SND1-IT1. RT-qPCR and dual-luciferase reporter assays verified the regulation of miR-132-3p by SND1-IT1 in RB cells. In addition, SND1-IT1 enhanced the expression of SMAD2 by sponging miR-132-3p. Rescue experiments revealed that knockdown of miR-132-3p reversed the inhibiting effects of miR-132-3p knockdown on RB cells. Overall, SND1-IT1 can promote the progression of RB cells through miR-132-3p/SMAD2 axis, suggesting that l SND1-IT1 might be a novel biomarker and potential target for RB.

CircCUL2 suppresses retinoblastoma cells by regulating miR-214-5p/E2F2 Axis

The aim of this study was to investigate the effect of circCUL2 on the proliferation, invasion and migration of retinoblastoma cells by regulating the miR-214-5p/E2F2 axis. qRT-PCR and western blot were performed to detect the expressions of circCUL2, miR-214-5p and E2F2 in tumor tissues and adjacent normal tissues from retinoblastoma patients, and in normal human retinal epithelial cells ARPE-19 and human retinoblastoma cells Y79 and SO-Rb50. qRT-PCR and western blot were performed for the detection of RNA levels of circCUL2 and miR-214-5p and the mRNA and protein levels of E2F2, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay for cell proliferation ability, Transwell assay for cell invasion ability, and scratch assay for cell migration ability. Luciferase dual reporter assay was used to detect the targeting relationship between circCUL2 and miR-214-5p, and between miR-214-5p and E2F2. CircCUL2 and E2F2 were lowly expressed, while miR-214-5p was highly expressed in retinoblastoma tumor tissues and cells. Transfection with pcDNA3.1-CUL2 or miR-214-5p inhibitor inhibited the proliferation, invasion and migration of Y79 and SO-Rb50 cells compared with the negative control; while transfection with sh-CUL2 or miR-214-5p mimics promoted the proliferation, invasion and migration of Y79 and SO-Rb50 cells. CircCUL2 negatively regulated miR-214-5p, while miR-214-5p negatively regulated E2F2. Overexpression of miR-214-5p or silencing of E2F2 in SO-Rb50 cells partially reversed the inhibitory effect of circCUL2 on the proliferation, invasion and migration of retinoblastoma cells. CircCUL2 inhibited the proliferation, invasion and migration of retinoblastoma cells by regulating the miR-214-5p/E2F2 axis.

Therapeutic Targeting PLK1 by ON-01910.Na Is Effective in Local Treatment of Retinoblastoma

Cell cycle deregulation is involved in the pathogenesis of many cancers and is often associated with protein kinase aberrations, including the polo-like kinase 1 (PLK1). We used retinoblastoma, an intraocular malignancy that lacks targeted therapy, as a disease model and set out to reveal targetability of PLK1 with a small molecular inhibitor ON-01910.Na. First, transcriptomic analysis on patient retinoblastoma tissues suggested that cell cycle progression was deregulated and confirmed that PLK1 pathway was upregulated. Next, antitumor activity of ON-01910.Na was investigated in both cellular and animal levels. Cytotoxicity induced by ON-01910.Na was tumor specific and dose dependent in retinoblastoma cells, while nontumor cells were minimally affected. In three-dimensional culture, ON-01910.Na demonstrated efficient drug penetrability with multilayer cell death. Posttreatment transcriptomic findings revealed that cell cycle arrest and MAPK cascade activation were induced following PLK1 inhibition and eventually resulted in apoptotic cell death. In Balb/c nude mice, a safe threshold of 0.8 nmol intravitreal dosage of ON-01910.Na was established for intraocular safety, which was demonstrated by structural integrity and functional preservation. Furthermore, intraocular and subcutaneous xenograft were significantly reduced with ON-01910.Na treatments. For the first time, we demonstrated targetability of PLK1 in retinoblastoma by efficiently causing cell cycle arrest and apoptosis. Our study is supportive that local treatment of ON-01910.Na may be a novel, effective modality benefiting patients with PLK1-aberrant tumors.

TRIB3 promotes proliferation, migration, and invasion of retinoblastoma cells by activating the AKT/mTOR signaling pathway

BACKGROUND

Tribbles pseudokinase 3 (TRIB3) is a member of the tribbles-related family, which has been determined in various cancers, including renal cell carcinoma, acute promyelocytic leukemia, colorectal cancer, endometrial cancer, and glioma. However, its role in retinoblastoma (RB) has not yet been explored.

METHODS

The expression level of TRIB3 was detected in RB tissues and cell lines using qRT-PCR. The effects of TRIB3 on cell proliferation and invasion capacities were analyzed with MTT, crystal violet, and transwell assays. Western blot and rescue assays were conducted to explore the underlying mechanism.

RESULTS

This study found that TRIB3 was upregulated in human RB tissues compared to adjacent normal tissues both at the mRNA and protein levels. Overexpression of TRIB3 significantly promoted cell proliferation and invasion of RB cells, while TRIB3 knockdown inhibited these processes. Moreover, the mechanism deciphering experiments showed that TRIB3 overexpression can increase AKT and mTOR phosphorylation. Conversely, TRIB3 knockdown decreased the phosphorylation of AKT and mTOR. Additionally, MK2206, a potent AKT inhibitor, blocked the promotive effects of TRIB3 in RB cells.

CONCLUSION

This study demonstrated that TRIB3 acts as an oncogene and plays a crucial role in the proliferation and invasion of RB cells via regulating the AKT/mTOR signaling pathway. Therefore, TRIB3 may serve as a potential target in the diagnosis and/or treatment of RB.

Long non‑coding RNA SNHG20 promotes cell proliferation, migration and invasion in retinoblastoma via the miR‑335‑5p/E2F3 axis

Current therapies for retinoblastoma (RB) are unsatisfactory and there is an urgent need for the development of new treatment modalities. Small nucleolar RNA host gene 20 (SNHG20) has been reported to serve a key oncogenic role in the development of various types of cancer, but its role in RB tumorigenesis remains to be fully determined. The present study aimed to investigate the expression patterns and biological roles of SNHG20 in RB. The expression levels of SNHG20 were measured via reverse transcription‑quantitative PCR in RB tissues and cell lines. The impact of SNHG20 status on cell proliferation, survival, migration and invasion was determined using small interfering RNA and a range of established experimental assays. The SNHG20/microRNA (miR)‑335‑5p/E2F transcription factor 3 (E2F3) signaling axis was further investigated using a dual‑luciferase activity reporter system and an RNA pull‑down assay combined with bioinformatics analyses. SNHG20 expression was significantly increased in RB tissues and cell lines. Silencing of SNHG20 in RB cells was shown to inhibit cell proliferation, clonogenic survival, migration and invasion. Moreover, mechanistic investigations demonstrated that SNHG20 could enhance the expression of E2F3 by sponging of miR‑335‑5p. These data suggested that the long non‑coding RNA SNHG20 may promote cell proliferation, migration and invasion in RB via the miR‑335‑5p/E2F3 axis.

Outcomes of neonatal retinoblastoma in pre-chemotherapy and chemotherapy eras

Purpose

To quantify outcomes for neonatal retinoblastoma patients treated during the pre-chemotherapy (1980-1994) and chemotherapy (1995-2018) eras.

Methods

Retrospective review of retinoblastoma patients diagnosed within the first 28 days of life between 1/1/1980 and 11/30/2018. Student's t-test, Chi-square, and Fisher's exact test were performed to compare treatments and outcomes by era.

Results

There were 68 patients with neonatal retinoblastoma (12% unilateral and 88% bilateral). According to era (pre-chemotherapy vs. chemotherapy), the number of treated patients was 26 (38%) vs. 42 (62%). Primary treatment was external beam radiotherapy (50% vs. 1%,P < 0.001), plaque radiotherapy (17% vs. 0%,P < 0.001), focal treatment (transpupillary thermotherapy or cryotherapy) only (21% vs. 14%,P= 0.33), intravenous chemotherapy (0% vs. 81%,P < 0.001), enucleation (10% vs. 4%,P= 0.26), or exenteration (2% vs. 0%,P= 0.37). Outcomes included tumor control (79% vs. 94%,P= 0.02), globe salvage (75% vs. 91%,P= 0.02), final gross visual acuity for salvaged eyes 20/200 or better (66% vs. 89%,P < 0.01), and death (19% vs. 0%,P < 0.01).

Conclusion

Chemotherapy advancements for neonatal retinoblastoma have improved tumor control, globe salvage, visual acuity, and patient survival.

Accuracy of preoperative imaging in predicting optic nerve invasion in retinoblastoma: A retrospective study

Purpose:

Optic nerve invasion is an important cause of mortality in retinoblastoma. We aimed correlate preoperative imaging and surgical histopathology findings in enucleated eyes with retinoblastoma to determine the efficacy of preoperative imaging in predicting optic nerve invasion in retinoblastoma.

Methods:

A retrospective review of records of all patients undergoing primary enucleation for retinoblastoma at a tertiary eyecare system between March 2013 and December 2017 with all patients having undergone preoperative imaging, either CT scan or MRI. Data was analyzed statistically to determine the correlation between preoperative CT scan/MRI and histopathology.

Results:

Totally, 97 eyes of 97 patients were included in the study who underwent primary enucleation for unilateral retinoblastoma. The average age at presentation was 27.8 months with the chief complaint being leukocoria in all the cases. 14 patients (14.43%) had evidence of optic nerve involvement in preoperative imaging. 30 patients had optic nerve invasion on histopathology (laminar and retrolaminar). Spearman's rank correlation test revealed a significant correlation between MRI findings and HP and an insignficant correlation between CT findings and HP. The CT scan had a sensitivity of 20%, specificity of 88.89%, 50% positive predictive value and 66.67% negative predictive value. MRI had a sensitivity of 40%, specificity of 93.55%, positive predictive value of 66.67% and a negative predictive value of 82.86%.

Conclusion:

MRI showed significant moderate correlation with surgical histopathology for predicting optic nerve invasion in retinoblastoma whereas CT shows insignificant correlation with HPE. Therefore, we recommend MRI for predicting optic nerve invasion in cases of retinoblastoma.

Clinical relevance of the comparative expression of immune checkpoint markers with the clinicopathological findings in patients with primary and chemoreduced retinoblastoma

PURPOSE

The goal of this study is to identify the pathological findings and expression of immune checkpoint marker (PD-1, PD-L1, and CTLA-4) in the tumor microenvironment of both primary and chemoreduced retinoblastoma and correlate them with clinicopathological parameters and patient outcome.

METHODS

Total of 262 prospective cases was included prospectively in which 144 cases underwent primary enucleation and 118 cases received chemotherapy/radiotherapy before enucleation (chemoreduced retinoblastoma). Immunohistochemistry, qRT-PCR and western blotting were performed to evaluate the expression pattern of immune checkpoint markers in primary and chemoreduced retinoblastoma.

RESULTS

Tumor microenvironment were different for both primary and chemoreduced retinoblastoma. Expression of PD-1 was found in 29/144 (20.13%) and 48/118 (40.67%) in primary and chemoreduced retinoblastoma, respectively, whereas PD-L1 was expressed in 46/144 (31.94%) and 22/118 (18.64%) in cases of primary and chemoreduced retinoblastoma, respectively. Expression pattern of CTLA-4 protein was similar in both groups of retinoblastoma. On multivariate analysis, massive choroidal invasion, bilaterality and PD-L1 expression (p = 0.034) were found to be statistically significant factors in primary retinoblastoma, whereas PD-1 expression (p = 0.015) and foamy macrophages were significant factors in chemoreduced retinoblastoma. Overall survival was reduced in cases of PD-L1 (80.76%) expressed primary retinoblastoma, and PD-1 (63.28%) expressed chemoreduced retinoblastoma.

CONCLUSIONS

This is the first of its kind study predicting a relevant role of the immune checkpoint markers in both groups of primary and chemoreduced retinoblastoma with prognostic significance. Differential expression of these markers in both group of retinoblastoma is a novel finding and might be an interesting and beneficial target for chemoresistant tumors.

Long non-coding RNA LEF1-AS1 is involved in the progression of retinoblastoma through regulating the Wnt/β-catenin pathway

The lymphoid enhancer binding factor 1 antisense RNA 1 (LEF1-AS1) has been suggested to function as a tumour-associated lncRNA in several types of human cancers, but there is no study to date about the role of LEF1-AS1 in retinoblastoma. In our study, LEF1-AS1 expression was increased in retinoblastoma tissues and cell lines compared with paired adjacent normal tissues and the retinal pigment epithelial cell line, respectively. Meanwhile, we found that patients with retinoblastoma with IIRC D-E or undifferentiated type had notably higher levels of LEF1-AS1 expression than those with IIRC A-C or differentiated type. High LEF1-AS1 expression predicted poor disease-free survival in patients with retinoblastoma. The in vitro assays suggested that silencing of LEF1-AS1 suppressed retinoblastoma cell proliferation, migration, and invasion through regulating the Wnt/β-catenin pathway. In conclusion, LEF1-AS1 functions as an oncogenic lncRNA in retinoblastoma.

LncRNA TMPO-AS1 up-regulates the expression of HIF-1α and promotes the malignant phenotypes of retinoblastoma cells via sponging miR-199a-5p

BACKGROUND

Long non-coding RNA (lncRNA) TMPO antisense RNA 1 (TMPO-AS1) is reported to be oncogenic in prostate cancer and lung cancer. This study aims to investigate the expression and biological function of it in retinoblastoma (RB), and explore its regulatory role for miR-199a-5p and hypoxia-inducible factor-1α (HIF-1α).

METHODS

Paired RB samples were collected, and the expression levels of TMPO-AS1, miR-199a-5p and HIF-1α were examined by quantitative real-time polymerase chain reaction (qRT-PCR); TMPO-AS1 overexpressing plasmids and TMPO-AS1 shRNA were transfected into HXO-RB44 and SO-Rb50 cell lines respectively, and then proliferation, migration and invasion of RB cells were detected by CCK-8 assay and Transwell method. qRT-PCR and western blot were used to analyze the regulatory function of TMPO-AS1 on miR-199a-5p and HIF-1α; luciferase reporter gene assay was used to determine the regulatory relationship between miR-199a-5p and TMPO-AS1.

RESULTS

TMPO-AS1 was significantly up-regulated in cancerous tissues of RB samples (relatively expression: 2.97 vs 3.93, p < 0.001), negatively correlated with miR-199a-5p (r=-0.4813, p < 0.01). There was one binding site on TMPO-AS1 for miR-199a-5p. After transfection of TMPO-AS1 shRNAs into RB cells, the proliferation, migration and invasion of cancer cells was significantly inhibited, while TMPO-AS1 had opposite effects; TMPO-AS1 was also demonstrated to regulate the expression of HIF-1α on both mRNA and protein levels via negatively regulating miR-199a-5p.

CONCLUSION

TMPO-AS1 is abnormally up-regulated in RB tissues, and it can modulate the proliferation and migration of RB cells. It has the potential to be the "ceRNA" to regulate HIF-1α expression by sponging miR-199a-5p.

Comparison of ocular pharmacokinetics of etoposide and its nanoemulsion after subtenon administration in rabbits

Background Subtenon anticancer drugs are given as an adjunct to systemic chemotherapy for conditions like retinoblatoma. This study evaluated the ocular kinetics of nano-emulsion formulation of etoposide (NanoEt) and compared it with an equal dose of commercially available alcohol-based etoposide formulation in healthy rabbits. Methods A nanoemulsion formulation of NanoEt was developed and then evaluated for its ocular kinetics by subtenon administration in healthy rabbits. After the sterile subtenon administration of the drug, the eyes were enucleated after CO2 euthanasia at time intervals of 2 h, 6 h, 12 h, and 24 h, and ocular tissues, blood, and plasma were separated. The concentration of etoposide in the ocular tissues and blood was quantified using liquid chromatography tandem mass spectrometry (LC MS/MS). Results This study found that subtenon injection of NanoEt showed 24 times higher concentration in rabbit retina compared to an equal dose of conventional marketed formulation. Based on the ocular tissue bioavailability calculations (AUC0-24), the present study revealed that the formulation enhanced 90% ocular bioavailability of etoposide, when it was injected in the form of nano-emulsion in most of the tissues. Conclusions NanoEt has better bioavailability compared to the commercial alcohol-based formulation for subtenon injection. Low systemic exposure showed further advantage for its projected use in retinoblastoma (Rb) as an adjunct therapy. Further studies in Rb animal models are required to evaluate its safety and efficacy, for its clinical utility.

Intra-Arterial Chemotherapy for Retinoblastoma: Four-Year Results from Tertiary Center in India

Background

There are limited reports of intra-arterial chemotherapy (IAC) for retinoblastoma (RB) from developing world.

Objectives

In this study, we report our 4-year experience of IAC for RB from India.

Methods

Retrospective, interventional case series. Primary outcome measures included tumor regression, vitreous seeds and subretinal seeds control, and globe salvage. Secondary outcome measures were best-corrected visual acuity and treatment complications.

Results

Fifteen eyes underwent 53 IAC procedures over mean 28.6 ± 13.8 months (range 10-51 months). IAC was employed as primary (n = 6) or secondary (n = 9) chemotherapy. Following IAC, complete regression of main tumor was seen in 7 eyes (47%) and partial regression in 3 (20%) eyes. Enucleation was done in 5(33%) eyes. Globe salvage rates were achieved in 1 eye (100%) in group B, 2 eyes (67%) in group C (n = 3), 6 eyes (67%) in group D (n = 9), and 1 eye (50%) in group E (n = 2). Following IAC, Kaplan-Meier survival curve showed 93% globe survival rate at 1 year, 76% at 2 years, and 66% at 3, and 4 years.

Conclusion

IAC has enhanced globe salvage rates in eyes with RB. Multicenter studies with longer follow-up are necessary to better understand outcomes in the long term.

Co-delivery of miR-181a and melphalan by lipid nanoparticles for treatment of seeded retinoblastoma

Melphalan is an efficient chemotherapeutic agent that is currently used to treat retinoblastoma (Rb); however, the inherent risk of immunogenicity and the hazardous integration of this drug in healthy cells is inevitable. MicroRNAs are short non-coding single-stranded RNAs that affect a vast range of biological processes. Previously, we focused on the regulatory role of miR-181a during cancer development and progression. In this manuscript, 171 nm switchable lipid nanoparticles (LNP) co-delivered melphalan and miR-181a with encapsulation efficiencies of 93%. Encapsulation of melphalan in LNP significantly improved its therapeutic efficiency. Gene analysis shows that miR-181a decreases the expression of anti-proliferative gene MAPK1 and anti-apoptotic gene Bcl-2, but significantly increased the expression of pro-apoptotic gene BAX. Our results suggest that the two agents have a complementary effect in reducing the viability of cultured Rb cells (primary and cell line) and decreasing Rb cell counts in an in-vivo xenograft Rb model in rats. Our results suggest that the proposed co-delivery technique significantly increases the therapeutic impact, allows for lower administration of melphalan, and consequently, could minimize the cytotoxic side-effects of this drug.

Evolving Radiotherapy Techniques in Paediatric Oncology

AIMS

Childhood cancer is rare and survival of childhood cancer has increased up to 80% at 5 years after diagnosis. Radiotherapy is an important element of the multimodal treatment concept. However, due to growing tissue, children are particularly sensitive to radiation-related side-effects and the induction of secondary malignancies. However, radiotherapy techniques have continuously progressed. In addition, modern treatment concepts have been improved in order to minimise long-term effects. Today, radiotherapy is used for various tumour types in childhood, such as sarcomas and tumours of the central nervous system.

MATERIALS AND METHODS

External beam therapy with either photons or protons and brachytherapy are predominantly used for the treatment of childhood tumours. Technical developments and features, as well as clinical outcomes, for several tumour entities are presented.

RESULTS

The development of radiotherapy techniques, as well as risk-adapted therapy concepts, resulted in promising outcome regarding tumour control, survival and therapy-related side-effects. It is assumed that proton therapy will be increasingly used for treating children in the future. However, more data have to be collected through multi-institutional registries in order to strengthen the evidence.

CONCLUSION

The development of radiotherapy techniques is beneficial for children in terms of reducing dose exposure. As compared with other modern and highly conformal techniques, particularly proton therapy may achieve high survival rates and tumour control rates while decreasing the risk for side-effects. However, clinical evidence for modern radiotherapy techniques is still limited today. An optimal patient triaging with the selection of the most appropriate radiation technique for each individual patient will be an important goal for the future.

9.4T and 17.6T MRI of Retinoblastoma: Ex Vivo evaluation of microstructural anatomy and disease extent compared with histopathology

BACKGROUND

Retinoblastoma is the most common intraocular tumor in childhood with a good prognosis in terms of mortality, but detailed information about tumor morphology and disease extent in retinoblastoma is important for treatment decision making.

PURPOSE

To demonstrate ultrahigh-field MRI tumor morphology and tumor extent in retinoblastoma correlating with in and ex vivo images with histopathology.

STUDY TYPE

Prospective case series.

POPULATION

Six retinoblastoma patients (median age 5.5 months, range 2-14) were prospectively included in this study. Median time between diagnosis and enucleation was 8 days (range 7-19).

FIELD STRENGTH/SEQUENCE

In vivo pre-enucleation at 1.5T MRI with a circular surface coil. Ex vivo imaging (FLASH T₁ -weighted and RARE T₂ -weighted) was performed at field strengths of 9.4T and 17.6T.

ASSESSMENT

After ex vivo imaging, the eyes were histopathologically analyzed and morphologically matched with MRI findings by three authors (two with respectively 14 and 4 years of experience in ocular MRI and one with 16 years of experience in ophthalmopathology).

RESULTS

Small submillimeter morphological aspects of intraocular retinoblastoma were successfully depicted with higher-resolution MRI and matched with histopathology images. With ex vivo MRI a small subretinal tumor seed (300 μm) adjacent to the choroid was morphologically matched with histopathology. Also, a characteristic geographical pattern of vital tumor tissue (400 μm) surrounding a central vessel interspersed with necrotic areas correlated with histopathology images. Tumor invasion into the optic nerve showed a higher signal intensity on T₁ -weighted higher-resolution MRI.

DATA CONCLUSION

Higher-resolution MRI allows for small morphological aspects of intraocular retinoblastoma and extraocular disease extent not visible on currently used clinical in vivo MRI to be depicted.

LEVEL OF EVIDENCE

4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1487-1497.