[Retinoblastoma]

Fatty acid conjugated EPI-X4 derivatives with increased activity and in vivo stability

Dysregulation of the CXCL12/CXCR4 axis is implicated in autoimmune, inflammatory, and oncogenic diseases, positioning CXCR4 as a pivotal therapeutic target. We evaluated optimized variants of the specific endogenous CXCR4 antagonist, EPI-X4, addressing existing challenges in stability and potency. Our structure-activity relationship study investigates the conjugation of EPI-X4 derivatives with long-chain fatty acids, enhancing serum albumin interaction and receptor affinity. Molecular dynamic simulations revealed that the lipid moieties stabilize the peptide-receptor interaction through hydrophobic contacts at the receptor's N-terminus, anchoring the lipopeptide within the CXCR4 binding pocket and maintaining essential receptor interactions. Accordingly, lipidation resulted in increased receptor affinities and antagonistic activities. Additionally, by interacting with human serum albumin lipidated EPI-X4 derivatives displayed sustained stability in human plasma and extended circulation times in vivo. Selected candidates showed significant therapeutic potential in human retinoblastoma cells in vitro and in ovo, with our lead derivative exhibiting higher efficacies compared to its non-lipidated counterpart. This study not only elucidates the optimization trajectory for EPI-X4 derivatives but also underscores the intricate interplay between stability and efficacy, crucial for delineating their translational potential in clinical applications.

Evidence in Focus: The Sparse Landscape of Randomized Trials on Retinoblastoma Treatment

Background

Retinoblastoma, although rare, is one of the most common intraocular malignancies worldwide. Its prognosis has improved significantly in the past few decades, thanks to modern treatments, like systemic, intra-arterial, and intravitreal chemotherapy. However, regarding survival, there are significant differences between high- and low-income countries, eye salvage is still a challenge worldwide, and treatment-related toxicity needs to be carefully and sufficiently managed.

Summary

To appraise the strength of supporting evidence, we performed a systematic review of randomized controlled trials investigating any therapeutic protocol for retinoblastoma. Four trials with 174 participants (188 eyes) were eligible, all pertaining to different intravenous chemotherapy regimens. Vincristine, etoposide, and carboplatin (VEC) appear superior to a 5-drug combination for stage III retinoblastoma. Moreover, etoposide and carboplatin as neoadjuvant chemotherapy followed by thermochemotherapy seem to offer better local control than vincristine and carboplatin. However, increasing carboplatin dose in the VEC protocol failed to improve treatment efficacy.

Key Messages

Retinoblastoma is a success story of modern medicine. However, only intravenous chemotherapy has been studied through randomized trials, while evidence for the most novel retinoblastoma treatments has mainly stemmed from observational studies. International collaborations for multicenter randomized trials could overcome difficulties and increase certainty and precision in the field.

PDGF, NGF, and EGF as main contributors to tumorigenesis in high-risk retinoblastoma

Retinoblastoma (RB) is the most common form of eye cancer experienced in childhood. Its aggressive malignancy is associated with excellent survival rates in high-income countries; however, the prognosis in third-world countries is less favorable. Early diagnosis can maximize the patient's visual outcomes and their survival rate. Therapy should be conducted in highly specialized treatment centers. Intravenous chemotherapy (IVC) in bilaterally affected children currently forms the majority of therapy. Local destructive procedures and local chemotherapies such as intra-arterial chemotherapy (IAC) or intravitreal chemotherapy can be taken into consideration depending on the extent and size of the tumor. Nonetheless, children and parents remain under constant stress, revisiting doctors for medical treatment and fearing vision loss and even enucleation of the eye. Adequate molecular patient stratification to improve targeted therapy is still lacking. This retrospective study analyzed formalin-fixed paraffin-embedded specimens from a cohort of 21 RB samples. A total of 11 of those samples showed undifferentiated retinoblastoma (URB) histopathological risk features, and the other 10 showed differentiated retinoblastoma (DRB) histopathological grading. RNA from all samples was isolated and analyzed via digital gene expression patterns. Conductors of cell survival and DNA repair were dominant in the DRB samples. In contrast, the agents responsible for cell-cycle progression and apoptosis were overexpressed in URB samples. Our work reveals the importance of molecular mechanisms within the immune system subjected to histologic subtypes of RB, providing more detailed background on their genetic behavior. This is of great interest for therapeutic strategies, such as targeted immune- and gene-based therapies, for retinoblastoma.

Trefoil Family Factor Peptide 1-A New Biomarker in Liquid Biopsies of Retinoblastoma under Therapy

Effective management of retinoblastoma (RB), the most prevalent childhood eye cancer, depends on reliable monitoring and diagnosis. A promising candidate in this context is the secreted trefoil family factor peptide 1 (TFF1), recently discovered as a promising new biomarker in patients with a more advanced subtype of retinoblastoma. The present study investigated TFF1 expression within aqueous humor (AH) of enucleated eyes and compared TFF1 levels in AH and corresponding blood serum samples from RB patients undergoing intravitreal chemotherapy (IVC). TFF1 was consistently detectable in AH, confirming its potential as a biomarker. Crucially, our data confirmed that TFF1-secreting cells within the tumor mass originate from RB tumor cells, not from surrounding stromal cells. IVC-therapy-responsive patients exhibited remarkably reduced TFF1 levels post-therapy. By contrast, RB patients' blood serum displayed low-to-undetectable levels of TFF1 even after sample concentration and no therapy-dependent changes were observed. Our findings suggest that compared with blood serum, AH represents the more reliable source of TFF1 if used for liquid biopsy RB marker analysis in RB patients. Thus, analysis of TFF1 in AH of RB patients potentially provides a minimally invasive tool for monitoring RB therapy efficacy, suggesting its importance for effective treatment regimens.

Tumor Suppressor Role of INPP4B in Chemoresistant Retinoblastoma

The chemotherapy of retinoblastoma (RB), a malignant ocular childhood disease, is often limited by the development of resistance against commonly used drugs. We identified inositol polyphosphate 4-phosphatase type II (INPP4B) as a differentially regulated gene in etoposide-resistant RB cell lines, potentially involved in the development of RB resistances. INPP4B is controversially discussed as a tumor suppressor and an oncogenic driver in various cancers, but its role in retinoblastoma in general and chemoresistant RB in particular is yet unknown. In the study presented, we investigated the expression of INPP4B in RB cell lines and patients and analyzed the effect of INPP4B overexpression on etoposide resistant RB cell growth in vitro and in vivo. INPP4B mRNA levels were significantly downregulated in RB cells lines compared to the healthy human retina, with even lower expression levels in etoposide-resistant compared to the sensitive cell lines. Besides, a significant increase in INPP4B expression was observed in chemotherapy-treated RB tumor patient samples compared to untreated tumors. INPP4B overexpression in etoposide-resistant RB cells resulted in a significant reduction in cell viability with reduced growth, proliferation, anchorage-independent growth, and in ovo tumor formation. Caspase-3/7-mediated apoptosis was concomitantly increased, suggesting a tumor suppressive role of INPP4B in chemoresistant RB cells. No changes in AKT signaling were discernible, but p-SGK3 levels increased following INPP4B overexpression, indicating a potential regulation of SGK3 signaling in etoposide-resistant RB cells. RNAseq analysis of INPP4B overexpressing, etoposide-resistant RB cell lines revealed differentially regulated genes involved in cancer progression, mirroring observed in vitro and in vivo effects of INPP4B overexpression and strengthening INPP4B’s importance for cell growth control and tumorigenicity.

[Imaging of retinoblastoma : Current state-of-the-art and future prospects]

BACKGROUND

Retinoblastoma is the most common malignant eye tumor in children and is associated with tumor predisposition syndrome (RB1 mutation) in up to 40% of cases. Imaging is an important part of the diagnostic workup of children with retinoblastoma both during the initial diagnosis and follow-up.

OBJECTIVES

The goal of this review is to present the current state-of-the-art regarding imaging of children with retinoblastoma, including technical background and diagnostic clues with a brief discussion of future prospects. In addition, we summarize the general clinical diagnostic workup and therapeutic options.

MATERIALS AND METHODS

Review of the literature and our own experience in the imaging of retinoblastoma.

CONCLUSION

High-resolution magnetic resonance imaging (MRI) is the imaging modality of choice in children with retinoblastoma for diagnosis (estimation of diagnosis/differential diagnosis, evaluation of local and intracranial tumor extension) and during follow-up. Despite the characteristic calcifications, computed tomography (CT) examinations are no longer indicated in these patients. Due to the high association with tumor predisposition syndrome, genetic counselling is recommended.

Combination of Brachytherapy and Intravitreal Chemotherapy in the Treatment of Retinoblastoma with Vitreous Seeding

Purpose

The aim of this study was to report the efficacy of combined intravitreal chemotherapy (IVC) and ruthenium-106 brachytherapy in retinoblastoma, either as first-line or second-line treatment, following systemic chemoreduction or intra-arterial chemotherapy.

Methods

Retrospective data of 18 eyes from 18 patients treated with IVC and brachytherapy from August 2014 to December 2019 were collected.

Results

The method described was our first-line therapy in 6 patients, whereas it was used as second-line treatment after chemoreduction in the remaining 12 patients. The eyes showed the following classification at initial presentation: 2 group B eyes, 3 group C eyes, and 13 group D eyes. The mean follow-up was 19.5 months (range 2-53 months). The mean patient age at brachytherapy was 34.0 months (range 15-83 months). The median prescribed dose at the tumour base and apex was 574.5 ± 306.7 Gy and 88.5 ± 12.2 Gy, respectively. The ocular retention rate was 66.7%. Six eyes had to be enucleated due to uncontrollable subretinal and recurrent vitreous seeding, tumour relapse, recurrence of a solid tumour elsewhere in the eye, and persistent vitreous bleeding with loss of tumour control. The mean number of intravitreal injections of melphalan was 5.0. Two patients received a simultaneous injection of topotecan for insufficient therapeutic response. With regard to radiogenic complications, we could observe temporary retinal and vitreous bleeding (27.8%), serous retinal detachment (44.4%), and radiogenic maculopathy and retinopathy (11.1%). None of the children showed metastatic disease during follow-up.

Conclusion

Ruthenium-106 plaque therapy in combination with IVC is an effective local therapy with good tumour control rates even in advanced eyes. Overall, the analysed therapeutic approach shows an acceptable side-effect profile, especially when considering that external-beam radiation therapy and systemic polychemotherapy or at least the number of cycles needed, with their increased incidence of adverse events, can thus be avoided.

Islet Co-Expression of CD133 and ABCB5 in Human Retinoblastoma Specimens

BACKGROUND

The role of CD133 und ABCB5 is discussed in treatment resistance in several types of cancer. The objective of this study was to evaluate whether CD133⁺/ABCB5⁺ colocalization differs in untreated, in beam radiation treated, and in chemotherapy treated retinoblastoma specimens. Additionally, CD133, ABCB5, sphingosine kinase 1, and sphingosine kinase 2 gene expression was analyzed in WERI-RB1 (WERI RB1) and etoposide-resistant WERI RB1 subclones (WERI ETOR).

METHODS

Active human untreated retinoblastoma specimens (n = 12), active human retinoblastoma specimens pretreated with beam radiation before enucleation (n = 8), and active human retinoblastoma specimens pretreated with chemotherapy before enucleation (n = 7) were investigated for localization and expression of CD133 and ABCB5 by immunohistochemistry. Only specimens with IIRC D, but not E, were included in this study. Furthermore, WERI RB1 and WERI ETOR cell lines were analyzed for CD133, ABCB5, sphingosine kinase 1, and sphingosine kinase 2 by the real-time polymerase chain reaction (RT-PCR).

RESULTS

Immunohistochemical analysis revealed the same amount of CD133⁺/ABCB5⁺ colocalization islets in untreated and treated human retinoblastoma specimens. Quantitative RT-PCR analysis showed a statistically significant upregulation of CD133 in WERI ETOR (p = 0.002). No ABCB5 expression was detected in WERI RB1 and WERI ETOR. On the other hand, SPHK1 (p = 0.0027) and SPHK2 (p = 0.017) showed significant downregulation in WERI ETOR compared to WERI RB1.

CONCLUSIONS

CD133⁺/ABCB5⁺ co-localization islets were noted in untreated and treated human retinoblastoma specimens. Therefore, we assume that CD133⁺/ABCB5⁺ islets might play a role in retinoblastoma genesis, but not in retinoblastoma treatment resistance.

Intraarterial Chemotherapy for Retinoblastoma - Initial Experiences of a German Reference Centre

BACKGROUND

Adequate management of retinoblastoma requires a multidisciplinary and individual approach to treatment. Intraarterial chemotherapy (IAC) is one of the most commonly used treatment modalities, and enables supraselective application of chemotherapy via the ophthalmic artery and is now established in almost all treatment centres. However, published treatment success rates are heterogeneous. There are some unanswered issues regarding sight-threatening ocular complications and the long-term occurrence of secondary malignancies and metastatic disease. The objective of the present study is to analyse the results of a German national reference centre.

METHODS

Retrospective analysis of all children with an indication for at least one IAC from April 2010 to April 2020. IAC was used either as primary or recurrence therapy. Obligatory follow-up was at least 6 months.

RESULTS

137 eyes of 127 children with an indication for IAC could be included. 12 eyes with a follow-up of less than 6 months and 37 eyes in which IAC was technically not feasible were excluded. In summary, 88 eyes of 79 children were finally analysed. Mean follow-up was 38 months, ranging from 7 to 117 months. In total, 195 procedures were completed. In 30 eyes (34.1%) IAC was conducted as primary and in 58 (65.9%) as secondary therapy. There was an initial IAC treatment response in 75 eyes (85.2%) with a recurrence-free rate of 61.3%. Eye salvage rate was 68.1% with 28 enucleated eyes in total. Ocular complications were observed in 36 eyes (40.9%), with 19 eyes (21.6%) showing severe sight-threatening and 11 eyes (12.5%) presenting minor non-sight-threatening toxic reactions. During follow-up, 1 child developed a secondary malignancy, 1 child developed metastasis and 1 child died as a consequence of trilateral retinoblastoma.

CONCLUSION

In summary, IAC is a potent modality for retinoblastoma treatment and has been very successful, even in advanced disease and heavily pretreated eyes. However, ocular complications should be taken in consideration, especially when the only seeing eye is treated. Long term incidences of secondary malignancies and metastatic diseases should be further investigated in prospective studies.

Autophagy-related gene 7 deficiency caused by miR-154-5p overexpression suppresses the cell viability and tumorigenesis of retinoblastoma by increasing cell apoptosis

Background

Retinoblastoma is a rare cancer of the retina that accounts for 3% of all childhood cancers. The aim of this study was to illuminate the oncogenic role and potential molecular mechanisms of the microRNA miR-154-5p and autophagy-related gene 7 (ATG7) in retinoblastoma, and to establish a nude mouse model in order to explore new therapeutic horizons for the disease.

Methods

Quantitative reverse transcription-polymerase chain reaction and western blot were performed to detect the expression levels of miR-154-5p and ATG7. The targeting relationship between miR-154-5p and ATG7 was analyzed by employing the luciferase reporter assay. MiR-154-5p mimic and pcDNA-ATG7 were transfected, either alone or in combination, into Y79 cells. The subsequent in vitro experiments involved four groups: the control group, miR-154-5p group, ATG7 group, and miR-154-5p + ATG7 group. Orthotopic xenograft models were established by injecting BALB/c athymic nude mice with treated and untreated Y79 cells.

Results

Y79 cells were transfected with miR-NC or miR-154-5p. Compared to those in the control group, the mRNA expression levels of miR-154-5p were increased in the miR-154-5p mimic group; in contrast, decreases were observed in the mRNA and protein expression levels of ATG7. Y79 cells were transfected with PcDNA or pcDNA-ATG7. The mRNA expression level of ATG7 was increased in pcDNA-ATG7 group. MiR-154-5p was found to have an element complementary to the three prime untranslated region of ATG7. Overexpression of miR-154-5p inhibited Y79 cells proliferation and migration, and promoted Y79 cells apoptosis via targeting of ATG7. In the in vivo experiment, the tumors of the miR-154-5p group of mice were significantly reduced in weight. Tumor growth and the protein levels of Survivin were both suppressed when miR-154-5p was overexpressed in vivo; however, cell apoptosis and the protein levels of p21 were promoted. In the miR-154-5p group, the expression levels of miR-154-5p were upregulated compared to those in the control group, but the ATG7 expression level was downregulated.

Conclusions

MiR-154-5p overexpression downregulated ATG7, which inhibited cell proliferation and apoptosis in vitro, as well as tumor formation in vivo.

Unilateral Leukocoria in an Infant

A nine-day-old male infant presents with his mother to the pediatric clinic with a concern of a white spot in his right eye. There was no history of antenatal or perinatal complications and the mother's serology was negative. Physical examination was remarkable only for leukocoria in the right eye. He was evaluated to have a Mittendorf dot. This is a benign clinical finding. Pupillary reflex check is an important part of a physical examination which can recognise pathological conditions such as cataract, retinoblastoma, metabolic errors with ocular manifestations and lead to early treatment before the child loses vision.