Ocular toxicity of intravitreal melphalan for retinoblastoma in Chinese patients

Safety of intravitreal chemotherapy in the management of retinoblastoma: A systematic review of the literature

Intravitreal chemotherapy is used as a salvage therapy for retinoblastoma with persistent or recurrent vitreous seeding after primary treatment. To assess the safety of this technique, we conducted a systematic review of all studies reporting ocular toxicity data. Forty-eight trials involving 2751 eyes were included. The most common complications were cataract, retinal toxicity, and vitreous hemorrhage. However, severe and permanent adverse events were limited, while the risk of extraocular dissemination, a significant concern, was practically eliminated through preventive techniques. Globe salvage rates ranged from 29 % to 100 %. In conclusion, intravitreal chemotherapy seems to improve prognosis of eyes with advanced disease, with an acceptable safety profile. Nevertheless, most relevant studies are retrospective, and no randomized trials have been performed. Recognizing the challenges regarding the conduct of randomized studies for such a rare pediatric cancer, we believe that multicenter trials through international collaborations can significantly enhance the available information.

Aqueous VEGF-A Levels as a Liquid Biopsy Biomarker of Retinoblastoma Vitreous Seed Response to Therapy

Purpose

Regression of retinoblastoma vitreous seeds (VS) during intravitreal chemotherapy can be delayed, resulting in supernumerary injections. Similarly, VS relapse may not be clinically evident at first. A predictive biomarker of tumor regression and relapse could help guide real-time clinical decision making. Retinoblastoma is an oxygen-sensitive tumor; paradoxically, VS survive in the hypoxic vitreous. We hypothesized that VS elaborate pro-angiogenic cytokines. The purpose was to determine if pro-angiogenic cytokine signatures from aqueous humor could serve as a biomarker of VS response to treatment.

Methods

Multiplex ELISA was performed on aqueous from rabbit eyes with human retinoblastoma VS xenografts to identify expressed proangiogenic cytokines and changes in aqueous cytokine levels during intravitreal treatment were determined. Confirmatory RNAscope in situ hybridization for VEGF-A was performed on human retinoblastoma tumor sections and VS xenografts from rabbits. For human eyes undergoing intravitreal chemotherapy, serial aqueous VEGF-A levels measured via VEGF-A-specific ELISA were compared to clinical response.

Results

VEGF-A was highly expressed in human retinoblastoma VS in the xenograft model, and was the only proangiogenic cytokine that correlated with VS disease burden. In rabbits, aqueous VEGF-A levels decreased in response to therapy, consistent with quantitative VS reduction. In patients, aqueous VEGF-A levels associated with clinical changes in disease burden (regression, stability, or relapse), with changes in VEGF-A levels correlating with clinical response.

Conclusions

Aqueous VEGF-A levels correlate with extent of retinoblastoma VS, suggesting that aqueous VEGF-A may serve as a predictive molecular biomarker of treatment response.

Risk factors for cataract in retinoblastoma management

AIMS

To investigate the risk factors for cataract following eye-preserving therapies for retinoblastoma.

METHODS

This retrospective, single-centre cohort study included patients diagnosed with retinoblastoma receiving eye-preserving therapies between January 2017 and June 2021. Cataract by the end of the follow-up was the main outcome.

RESULTS

Cataract was found in 31 of 184 (16.8%) included eyes during a mean follow-up of 27.6 months. The cataract and control groups were similar regarding patients' laterality, sex and disease stage. Eyes in the cataract group were more likely to present with endophytic retinoblastoma (p=0.02) and greater intraocular pressure (p=0.001). Competing risk regression analysis (univariate Fine-Gray model) showed that the growth pattern (p=0.01), intraocular pressure (p=0.01), number of intra-arterial chemotherapy (IAC) cycles (p=0.001), melphalan dose per IAC cycle (p=0.001) and number of intravitreous chemotherapy (IvitC) cycles (p=0.001) were associated with cataract occurrence. Multivariate analysis included higher intraocular pressure (p=0.003), a higher melphalan dose per IAC cycle (p=0.001) and an increasing number of IvitC cycles (p=0.04) as independent risk factors for cataract.

CONCLUSIONS

Repeated IAC and/or IvitC with melphalan were the most common eye-preserving therapies that induced cataract formation. The toxic effect of melphalan was an essential factor in cataract development, as indicated by the association of cataract occurrence with the melphalan dose.

Update on chemotherapy modalities for retinoblastoma: Progress and challenges

Retinoblastoma stands as a paradigm of success in treating malignancies among pediatric patients. Over recent decades, the approach to managing retinoblastoma has evolved significantly, transitioning from the preservation of patients' lives to the preservation of eyes and vision while minimizing treatment-related complications. Chemotherapy, administered through diverse routes, has solidified its role as the cornerstone of retinoblastoma treatment. In addition to intravenous chemotherapy (IVC), alternative administration routes, including intraarterial (IAC), intravitreal, intracameral, and periocular delivery, have emerged as promising modalities for retinoblastoma management. Numerous studies have demonstrated outstanding outcomes, achieving nearly 100% salvage rates for eyes classified under groups A-C. However, for advanced intraocular retinoblastoma (groups D and E eyes), IAC appears to offer superior local control rates compared to IVC. Intravitreal injection of chemotherapeutic agents, when administered in a controlled and secure manner, holds promise in averting the need for enucleation and radiotherapy in advanced retinoblastoma cases presenting with vitreous seeds. The optimal chemotherapy strategy remains meticulously tailored based on numerous factors. This review provides a comprehensive update on chemotherapy across various routes, encompassing key considerations, dosages, administration methods, treatment outcomes, and potential complications. Furthermore, it explores emerging potential treatments and outlines future directions aimed at enhancing treatment outcomes.

Retinal pigment epithelium exhibits gene expression and phagocytic activity alterations when exposed to retinoblastoma chemotherapeutics

Retinoblastoma (Rb) is a rare malignant disorder affecting the developing retina of children under the age of five. Chemotherapeutic agents used for treating Rb have been associated with defects of the retinal pigment epithelium (RPE), such as hyperplasia, gliosis, and mottling. Herein, we have developed two pluripotent stem cell (PSC)-RPE models to assess the cytotoxicity of known Rb chemotherapeutics such as Melphalan, Topotecan and TW-37. Our findings demonstrate that these drugs alter the RPE by decreasing the monolayer barrier's trans-epithelial resistance and affecting the cells' phagocytic activity. Transcriptional analyses demonstrate an altered expression of genes involved in melanin and retinol processing, tight junction and apical-basal polarity pathways in both models. When applied within the clinical range, none of the drug treatments caused significant cytotoxic effects, changes to the apical-basal polarity, tight junction network or cell cycle. Together, our results demonstrate that although the most commonly used Rb chemotherapeutic drugs do not cause cytotoxicity in RPE, their application in vitro leads to compromised phagocytosis and strength of the barrier function, in addition to changes in gene expression that could alter the visual cycle in vivo. Our data demonstrate that widely used Rb chemotherapeutic drugs can have a deleterious impact on RPE cells and thus great care has to be exercised with regard to their delivery so the adjacent healthy RPE is not damaged during the course of tumor eradication.

Toxicity to intravitreal melphalan in a patient with retinoblastoma

Objective: Description of melphalan's toxicity in retinoblastoma treatment. Methods: Clinical case report. Results: We presented a case of unilateral retinoblastoma with vitreous seeding at diagnosis, in which the use of intravitreal melphalan produced many adverse reactions. Conclusions: Vitreous seedings have been one of the most important challenges in retinoblastoma treatment. Intravitreal melphalan has achieved the regression of vitreous seedings in a large percentage of cases. It is a safe treatment; however, it can produce toxicity, even with the standard dose of 20-30 µg, which has been poorly documented. Exhaustive follow-up of patients is recommended for an early diagnosis of possible adverse effects. Abbreviations: OS = left eye, RI = magnetic resonance imaging, OCT = optical coherence tomography.

Ocular Survival Following Intravitreal Melphalan as Adjuvant Treatment for Vitreous Retinoblastoma Seeding

Purpose

To evaluate the efficacy of intravitreal chemotherapy for vitreous seeding in patients with retinoblastoma (Rb).

Design

Retrospective, single-arm cohort study.

Methods

This study was conducted at a tertiary eye center. Between 2013 and 2021, 27 patients (27 eyes) with vitreous Rb receiving adjuvant intravitreal melphalan (IVM) as secondary/salvage treatment in one eye were included. Patients who were unable to follow-up or treated elsewhere were excluded. Survival analysis was performed to assess the incidence of enucleation in the melphalan-treated group, as well as in bilateral cases with eyes receiving melphalan and those receiving standard treatment, consisting of chemotherapy, thermotherapy, and enucleation according to the disease stage.

Results

The median (interquartile range) follow-up time was 65 months (range, 34-83 months). Seventeen patients (63%) had bilateral disease. Sixteen eyes (59%) were saved. The Kaplan-Meier survival estimates for eyes receiving melphalan were 100% at 1 year (95% confidence interval [CI]:11.2-14.3), 75% (95% CI:14.2-48.9) at 3 years, and 50% at 5 years. Melphalan-treated patients with bilateral disease showed a significantly higher number of saved eyes than the standard treatment group (P=0.002). Tumor recurrence was the primary cause of enucleation, accounting for 36% of the cases. In the vitreous hemorrhage group, the odds of enucleation were 13 times higher (95% CI:1.04-165.28) than in the group without this condition.

Conclusion

IVM is an effective treatment option for vitreous seeds. After 3 years of follow-up, the estimated survival rate for saved eyes decreased, and vitreous hemorrhage significantly increased the likelihood of enucleation. Further studies are required to determine the precise effects of IVM.

Spotlight on Targeted Chemotherapy in Retinoblastoma: Safety, Efficacy, and Patient Outcomes

As the most common primary intraocular malignancy of childhood, retinoblastoma (RB) has had a complex journey in its management, following a course from enucleation as the first life-saving treatment to numerous globe-salvaging therapies during the last century. Currently, this potentially lethal disease has achieved high survival rates owing to multidisciplinary management and the introduction of neoadjuvant and multimodal chemotherapy. Therefore, the goal of treatment is shifting toward conserving the globe and vision as much as possible. Up until recently, many advanced cases of RB were enucleated primarily; however, targeted chemotherapy via the ophthalmic artery and management of intraocular seeding by local administration of chemotherapeutic agents have revolutionized the globe-conserving therapies. The added benefit of avoiding systemic complications of cytotoxic drugs resulted in these methods gaining popularity, and they are becoming a main part of care in many referral centers. Initially, there were some safety concerns regarding these approaches; however, increasing experience has shown that these modalities are relatively safe procedures and many complications can be averted by changing the choice of the drug and using some prophylactic measures. It is hoped that, in the near future, with advances in early diagnosis and patient-targeted molecular therapies, as well as gene-editing techniques, the patient's vision can be saved even in advanced RB.

Intravitreal Carboplatin as Salvage Treatment for Progressive Vitreous Disease in Retinoblastoma: a Phase I Clinical Trial

PURPOSE

To determine the safety and toxicity profile of intravitreal carboplatin as salvage treatment for retinoblastoma with vitreous disease.

DESIGN

Single-institution, interventional prospective clinical trial.

PARTICIPANTS

Patients with progressive or recurrent vitreous seeds after completion of primary treatment for intraocular retinoblastoma.

METHODS

Eligible eyes received an intravitreal injection of carboplatin every 14 to 21 days with simultaneous focal therapy (laser, thermotherapy, and brachytherapy) provided at the discretion of the ocular oncologist. The evaluation with examination under anesthesia, ultrasound biomicroscopy, and electroretinography (ERG) were performed before each injection to assess for tumor response and drug-related toxicity. A serious adverse event resulted in dose recalculation and ultimately early closure of the study.

MAIN OUTCOME MEASURES

Regression pattern of vitreous disease and incidence of dose-limiting toxicities.

RESULTS

Four patients were enrolled at an initial dose of 0.3 mg. Complete regression of vitreous seeds was noted in all patients after 5, 2, 2, and 1 injections (respectively). Two patients developed recurrent vitreous disease at 3 and 25 months after complete regression and ultimately required enucleation. A serious adverse event occurred in 1 patient who developed acute vision loss with extinguished ERG response 72 hours after the second injection; ultimately, this eye developed a cataract and required enucleation. After temporary suspension and dose modification, 3 patients were enrolled at an injection dose of 3 μg and treated with a total of 5, 2, and 1 injections, respectively. Complete regression of vitreous disease was not achieved in any patient though ERG amplitudes remained stable. After removal from protocol, all 3 patients had a complete response to intravitreal melphalan. Concern for dose escalation and further toxicity in the setting of an effective and safe alternative (melphalan) led to the termination of the study.

CONCLUSIONS

Intravitreal carboplatin may be effective in treating progressive vitreous seeding at higher doses, but permanent retinal toxicity was observed. Other alternative agents should be considered.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

A Rare Case of Acute Hemorrhagic Retinopathy Following Intravitreal Melphalan Injection for Persistent Vitreous Seeds in Retinoblastoma

Purpose:

This report describes a case of acute occlusive hemorrhagic complication after intravitreal melphalan for vitreous seeds in retinoblastoma.

Methods:

A case report is presented.

Results:

Intravitreal melphalan has been used extensively for vitreous seeds in retinoblastoma. Although melphalan is relatively safe at optimal doses, it can sometimes cause inadvertent complications like hemorrhagic events if the drug is administered close to the retina or in more pigmented eyes. We report a case of a 5-month-old patient with bilateral retinoblastoma who underwent enucleation of the right eye and 2 intravitreal melphalan injections in the left eye (20 µg/0.02 mL) at a 1-month interval for persistent vitreous seeds. After the second injection, there was a sudden decrease in the child’s visual acuity in the left eye, and the retina showed multiple intraretinal hemorrhages and diffuse chorioretinal atrophy.

Conclusion:

Intravitreal melphalan may cause acute hemorrhagic complications after intravitreal use for retinoblastoma seeds, especially in pigmented eyes.

Xanthatin Selectively Targets Retinoblastoma by Inhibiting the PLK1-Mediated Cell Cycle

Purpose

Retinoblastoma is the most common primary intraocular malignant tumor in children. Although intra-arterial chemotherapy and conventional chemotherapy have become promising therapeutic approaches for advanced intraocular retinoblastoma, the side effects threaten health and are unavoidable, making the development of targeted therapy an urgent need. Therefore, we intended to find a potential drug for human retinoblastoma by screening an in-house compound library that included 89 purified and well-characterized natural products.

Methods

We screened a panel of 89 natural products in retinoblastoma cell lines to find the inhibitor. The inhibition of the identified inhibitor xanthatin on cell growth was detected through half-maximal inhibitory concentration (IC50), flow cytometry assay, and zebrafish model system. RNA-seq further selected the target gene PLK1.

Results

We reported the discovery of xanthatin as an effective inhibitor of retinoblastoma. Mechanistically, xanthatin selectively inhibited the proliferation of retinoblastoma cells by inducing cell cycle arrest and promoting apoptosis. Interestingly, xanthatin targeted PLK1-mediated cell cycle progression. The efficacy of xanthatin was further confirmed in zebrafish models.

Conclusions

Collectively, our data suggested that xanthatin significantly inhibited tumor growth in vitro and in vivo, and xanthatin could be a potential drug treatment for retinoblastoma.

Intravitreal HDAC Inhibitor Belinostat Effectively Eradicates Vitreous Seeds Without Retinal Toxicity In Vivo in a Rabbit Retinoblastoma Model

Purpose

Current melphalan-based regimens for intravitreal chemotherapy for retinoblastoma vitreous seeds are effective but toxic to the retina. Thus, alternative agents are needed. Based on the known biology of histone deacetylases (HDACs) in the retinoblastoma pathway, we systematically studied whether the HDAC inhibitor belinostat is a viable, molecularly targeted alternative agent for intravitreal delivery that might provide comparable efficacy, without toxicity.

Methods

In vivo pharmacokinetic experiments in rabbits and in vitro cytotoxicity experiments were performed to determine the 90% inhibitory concentration (IC₉₀). Functional toxicity by electroretinography and structural toxicity by optical coherence tomography (OCT), OCT angiography, and histopathology were evaluated in rabbits following three injections of belinostat 350 µg (2× IC₉₀) or 700 µg (4× IC₉₀), compared with melphalan 12.5 µg (rabbit equivalent of the human dose). The relative efficacy of intravitreal belinostat versus melphalan to treat WERI-Rb1 human cell xenografts in rabbit eyes was directly quantified. RNA sequencing was used to assess belinostat-induced changes in RB cell gene expression.

Results

The maximum nontoxic dose of belinostat was 350 µg, which caused no reductions in electroretinography parameters, retinal microvascular loss on OCT angiography, or retinal degeneration. Melphalan caused severe retinal structural and functional toxicity. Belinostat 350 µg (equivalent to 700 µg in the larger human eye) was equally effective at eradicating vitreous seeds in the rabbit xenograft model compared with melphalan (95.5% reduction for belinostat, P < 0.001; 89.4% reduction for melphalan, P < 0.001; belinostat vs. melphalan, P = 0.10). Even 700 µg belinostat (equivalent to 1400 µg in humans) caused only minimal toxicity. Widespread changes in gene expression resulted.

Conclusions

Molecularly targeted inhibition of HDACs with intravitreal belinostat was equally effective as standard-of-care melphalan but without retinal toxicity. Belinostat may therefore be an attractive agent to pursue clinically for intravitreal treatment of retinoblastoma.

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.

Ocular safety of repeated intravitreal injections of Carboplatin and Digoxin: A preclinical study on the healthy rabbits

To evaluate the ocular safety of intravitreal carboplatin and digoxin injections as a new intravitreal chemotherapy option for retinoblastoma tumor vitreous seeds. Eighteen rabbits were divided randomly into three groups to receive intravitreal injection of Digoxin (6 rabbits), Carboplatin (7 rabbits), or Saline (5 rabbits). In every group, one eye randomly treated with 10 µg Digoxin in 0.1 cc or 1 µg Carboplatin or Saline, and the contralateral eye was considered as the control. All groups underwent three consecutive injections of the drugs with 1-week intervals. Baseline electroretinography (ERG) was recorded from both eyes of all the animals prior to injection and was repeated 1st day, 1st week, and 1st month after the last injection. All rabbits were sacrificed 1 month after the last injection, and histological studies were done. Mean a and b wave amplitudes decreased significantly at 1st day, 1st week, and 1st month after the last intravitreal injection of 10 µg Digoxin in comparison with other groups (p-value: .02). Contradictory, 1 µg Carboplatin injected eyes had minimal ERG changes. There were some nonspecific ERG changes with unclear clinical significance in non-injected contralateral control eyes of Digoxin and Carboplatin groups in comparison with the control eyes of the Saline group. Histological studies revealed considerable neural retinal atrophy in injected eyes of the Digoxin group. Intravitreal 10 µg Digoxin might have more local ocular toxicity in comparison with intravitreal Carboplatin in albino rabbit eyes. Future studies should assess the induced toxicity of intravitreal injection of these drugs on the non-injected contralateral eye.

Safety and Efficacy of Intravitreal Chemotherapy (Melphalan) to Treat Vitreous Seeds in Retinoblastoma

Background: Active vitreous seeds in eyes with retinoblastoma (Rb) adversely affects the treatment outcome. This study aimed to investigate the safety and efficacy of intravitreal melphalan chemotherapy (IViC) as a treatment for recurrent and refractory vitreous seeds in patients with Rb.

Methods: We used a retrospective non-comparative study of patients with intraocular Rb who had vitreous seeds and were treated by IViC (20–30 μg of melphalan) using the safety-enhanced anti-reflux technique. Tumor response, ocular toxicity, demographics, clinical features, and survival were analyzed.

Results: In total, 27 eyes were treated with 108 injections for recurrent (16 eyes) or refractory (11 eyes) vitreous seeds after failed systemic chemotherapy. A total of 15 (56%) were males, and 20 (74%) had bilateral disease. At diagnosis, the majority (n = 21) of the injected eyes were group D, and n = 6 were group C. Vitreous seeds showed complete regression in 21 (78%) eyes; 100% (n = 10) for eyes with focal seeds; 65% (n = 11/17 eyes) for eyes with diffuse seeds (p = 0.04); 7 (64%) eyes with refractory seeds; and 14 (87%) eyes with recurrent seeds showed complete response (p = 0.37). In total, 16 (59%) eyes developed side effects: retinal toxicity (48%), pupillary synechiae (15%), cataracts (30%), iris atrophy (7%), and retinal and optic atrophy (4%). Only one child was lost to follow-up whose family refused enucleation and none developed orbital tumor recurrence or distant metastasis.

Conclusion: IViC with melphalan is effective (more for focal than diffuse seeding) and a relatively safe treatment modality for Rb that can improve the outcomes of eye salvage procedures. However, unexpected toxicity can occur even with the standard dose of 20–30 μg.

Management of cataracts secondary to intravitreal chemotherapy injections for retinoblastoma seeding

PURPOSE

To report our experience in the management of cataracts presumably due to intravitreal chemotherapy administration in eyes with vitreous disease associated with retinoblastoma.

METHODS

This retrospective study consisted of a cohort of five eyes of five retinoblastoma patients who developed cataracts secondary to intravitreal chemotherapy administration and who then underwent cataract surgery. All patients underwent lensectomy and anterior vitrectomy with/without intraocular lens implantation via clear corneal approach. All cases were administered intraoperative intravitreal melphalan (35-40 mcg) and topotecan (10-20 mcg) at the end of cataract surgery as a preventive measure against retinoblastoma spread. Injections were repeated as needed in monthly follow-ups. Main outcome measures were enucleation rate and disease-free survival time.

RESULTS

The age at surgery ranged between 5 and 10 years. Follow-up time varied from 12 to 16 months. Treatment-free period before surgery ranged between 3 and 20 months. Time from last injection to cataract detection was: 2, 2, 10, 6, and 7 months; and time from last injection to cataract surgery was: 8, 3, 20, 7, and 15 months in cases 1-5, respectively. None of the eyes required enucleation. Tumor control was achieved in all patients at the end of follow-up.

CONCLUSIONS

Injection of melphalan and topotecan into anterior parts of the vitreous may lead to cataract formation. This can be safely managed with lensectomy and anterior vitrectomy and the use of intravitreal administration of melphalan and topotecan at the conclusion of the surgery as a precautionary measure against the potential risk of extraocular spread.

Evaluation of intravitreal topotecan dose levels, toxicity and efficacy for retinoblastoma vitreous seeds: a preclinical and clinical study

Background

Current melphalan-based intravitreal regimens for retinoblastoma (RB) vitreous seeds cause retinal toxicity. We assessed the efficacy and toxicity of topotecan monotherapy compared with melphalan in our rabbit model and patient cohort.

Methods

Rabbit experiments: empiric pharmacokinetics were determined following topotecan injection. For topotecan (15 μg or 30 µg), melphalan (12.5 µg) or saline, toxicity was evaluated by serial electroretinography (ERG) and histopathology, and efficacy against vitreous seed xenografts was measured by tumour cell reduction and apoptosis induction. Patients: retrospective cohort study of 235 patients receiving 990 intravitreal injections of topotecan or melphalan.

Results

Intravitreal topotecan 30 µg (equals 60 µg in humans) achieved the IC₉₀ across the rabbit vitreous. Three weekly topotecan injections (either 15 µg or 30 µg) caused no retinal toxicity in rabbits, whereas melphalan 12.5 µg (equals 25 µg in humans) reduced ERG amplitudes 42%–79%. Intravitreal topotecan 15 µg was equally effective to melphalan to treat WERI-Rb1 cell xenografts in rabbits (96% reduction for topotecan vs saline (p=0.004), 88% reduction for melphalan vs saline (p=0.004), topotecan vs melphalan, p=0.15). In our clinical study, patients received 881 monotherapy injections (48 topotecan, 833 melphalan). Patients receiving 20 µg or 30 µg topotecan demonstrated no significant ERG reductions; melphalan caused ERG reductions of 7.6 μV for every injection of 25 µg (p=0.03) or 30 µg (p<0.001). Most patients treated with intravitreal topotecan also received intravitreal melphalan at some point during their treatment course. Among those eyes treated exclusively with topotecan monotherapy, all eyes were salvaged.

Conclusions

Taken together, these experiments suggest that intravitreal topotecan monotherapy for the treatment of RB vitreous seeds is non-toxic and effective.

Complete preclinical platform for intravitreal chemotherapy drug discovery for retinoblastoma: Assessment of pharmacokinetics, toxicity and efficacy using a rabbit model

Current melphalan-based intravitreal chemotherapy regimens for retinoblastoma vitreous seeds are effective, but cause significant ocular toxicity. We describe protocols for each step of a drug discovery pipeline for preclinical development of novel drugs to maximize efficacy and minimize toxicity. These protocols include: 1) determination of vitreous pharmacokinetics in vivo, 2) in vitro assessment of drug cytotoxicity against retinoblastoma based on empiric pharmacokinetics, 3) back-calculation of minimum injection dose to achieve therapeutic concentrations, 4) in vivo determination of maximum-tolerable intravitreal dose, using a multimodal, structural and functional toxicity-assessment platform, and 5) in vivo determination of drug efficacy using a rabbit orthotopic xenograft model of retinoblastoma vitreous seeds. We likewise describe our methodology for direct quantitation of vitreous seeds, and the statistical methodology for assessment of toxicity and efficacy in evaluating novel drugs, as well as for comparisons between drugs.•Multi-step pipeline for intravitreal chemotherapy drug discovery for retinoblastoma, using novel rabbit models.•Detailed protocols for determination of vitreous pharmacokinetics, calculation of optimal dose to inject to achieve therapeutic vitreous levels, determination of maximum tolerable dose using a novel complete toxicity-assessment platform, and in vivo efficacy against retinoblastoma using methodology to directly quantify vitreous tumor burden.•Associated statistical methodology is also presented.

Multi-Functionalized Nanomaterials and Nanoparticles for Diagnosis and Treatment of Retinoblastoma

Retinoblastoma is a rare type of cancer, and its treatment, as well as diagnosis, is challenging, owing to mutations in the tumor-suppressor genes and lack of targeted, efficient, cost-effective therapy, exhibiting a significant need for novel approaches to address these concerns. For this purpose, nanotechnology has revolutionized the field of medicine with versatile potential capabilities for both the diagnosis, as well as the treatment, of retinoblastoma via the targeted and controlled delivery of anticancer drugs via binding to the overexpressed retinoblastoma gene. Nanotechnology has also generated massive advancements in the treatment of retinoblastoma based on the use of surface-tailored multi-functionalized nanocarriers; overexpressed receptor-based nanocarriers ligands (folate, galactose, and hyaluronic acid); lipid-based nanocarriers; and metallic nanocarriers. These nanocarriers seem to benchmark in mitigating a plethora of malignant retinoblastoma via targeted delivery at a specified site, resulting in programmed apoptosis in cancer cells. The effectiveness of these nanoplatforms in diagnosing and treating intraocular cancers such as retinoblastoma has not been properly discussed, despite the increasing significance of nanomedicine in cancer management. This article reviewed the recent milestones and future development areas in the field of intraocular drug delivery and diagnostic platforms focused on nanotechnology.

Vitreous Seed Classification and Regression Patterns in Eyes With Retinoblastoma

Purpose:

This work subclassifies retinoblastoma vitreous seeds and evaluates the efficacy, regression patterns, and adverse effects of combination intravitreal melphalan and topotecan chemotherapy for resistant and recurrent vitreous seeds.

Methods:

A retrospective review of medical records was conducted of patients with retinoblastoma and resistant or recurrent vitreous seeds who were treated with intravitreal melphalan and topotecan injections from August 2014 to July 2018. Main outcome measures included regression pattern, time for regression, time for recurrence of seeds, treatment outcomes, and ocular toxicity.

Results:

Nineteen eyes received 138 intravitreal injections over 74 treatment sessions (mean, 7.26 injections per eye); vitreous seeds regressed in 18 eyes. Of cloud vitreous seeds, curvilinear (n = 2) and sphero-linear (n = 2) subtypes were observed. During regression, some sphere seeds showed an intermediary streak-like pattern and took longer to regress (mean, 11.13 ± 14.05 months and 11.67 ± 8.62 injections) than those without the intermediary streak-like pattern (mean, 3.55 ± 2.57 months and 4.2 ± 1.87 injections). Mean follow-up was 34.87 ± 21.09 months (median, 35 months; range, 11-96 months). Anterior segment toxicity was seen in 10 (53%) eyes and posterior segment toxicity in 5 (26%) eyes. Kaplan-Meier survival estimates for globe salvage at 2 years was 94% and 73% at 5 years. Kaplan-Meier survival for vitreous seed–free status was 94% at 2 years and 65% at 5 years.

Conclusions:

An expanded vitreous seed classification system that further subcategorizes hitherto unrecognized vitreous seed morphology is needed. An intermediate streaking process results in a prolonged regression time for sphere vitreous seeds.

Intravitreal melphalan hydrochloride vs propylene glycol-free melphalan for retinoblastoma vitreous seeds: Efficacy, toxicity and stability in rabbits models and patients

The use of intravitreal chemotherapy has revolutionized the treatment of advanced intraocular retinoblastoma, as intravitreal melphalan has enabled difficult-to-treat vitreous tumor seeds to be controlled, leading to many more eyes being saved. However, melphalan hydrochloride (MH) degrades rapidly in solution, increasing logistical complexity with respect to time between medication preparation and administration for intravitreal administration under anesthesia for retinoblastoma. A new propylene glycol-free melphalan (PGFM) formulation has greater stability and could therefore improve access and adoption of intravitreal chemotherapy, allowing more children to retain their eye(s). We compared the efficacy and toxicity of both formulations, using our rabbit xenograft model and clinical patient experience. Three weekly 12.5 μg intravitreal injections of MH or PGFM (right eye), and saline (left eye), were administered to immunosuppressed rabbits harboring human WERI-Rb1 vitreous seed xenografts. Residual live cells were quantified directly, and viability determined by TUNEL staining. Vitreous seeds were reduced 91% by PGFM (p = 0.009), and 88% by MH (p = 0.004; PGFM vs. MH: p = 0.68). All residual cells were TUNEL-positive (non-viable). In separate experiments to assess toxicity, three weekly 12.5 μg injections of MH, PGFM, or saline were administered to non-tumor-bearing rabbits. Serial electroretinography, optical coherence tomography (OCT) and OCT-angiography were performed. PGFM and MH both caused equivalent reductions in electroretinography amplitudes, and loss of retinal microvasculature on OCT-angiography. The pattern of retinal degeneration observed on histopathology suggested that segmental retinal toxicity associated with all melphalan formulations was due to a vitreous concentration gradient-effect. Efficacy and toxicity were assessed for PGFM given immediately (within 1 h of reconstitution) vs. 4 h after reconstitution. Immediate- and delayed-administration of PGFM showed equivalent efficacy and toxicity. In addition, we evaluated efficacy and toxicity in patients (205 eyes) with retinoblastoma vitreous seeds, who were treated with a total of 833 intravitreal injections of either MH or PGFM as standard of care. Of these, we analyzed 118 MH and 131 PGFM monotherapy injections in whom serial ERG measurements were available to model retinal toxicity. Both MH and PGFM caused reductions in electroretinography amplitudes, but with no statistical difference between formulations. Comparing those patient eyes treated exclusively with PGFM versus those treated exclusively with MH, efficacy for tumor control and globe salvage was equivalent (PGFM vs. MH: 96.2% vs. 93.8%, p = 0.56), but PGFM-treated eyes received fewer injections than MH-treated eyes (average 3.2 ± 1.9 vs. 6.4 ± 2.1 injections, p < 0.0001). Taken together, these rabbit experiments and our clinical experience in retinoblastoma patients demonstrate that MH and PGFM have equivalent efficacy and toxicity. PGFM was more stable, with no decreased efficacy or increased toxicity even 4 h after reconstitution. We therefore now use PGFM over traditional MH for our patients for intravitreal treatment of retinoblastoma.

Intravitreal Melphalan for Retinoblastoma: The Impact of Toxicity on Recurrence and Ultimate Globe Salvage

Introduction

Intravitreal melphalan (IVM) has emerged as an efficacious treatment for vitreous seeding in retinoblastoma. Although rarely severe, IVM-related toxicity may be treatment limiting. There is paucity of data on the impact of IVM toxicity on new tumor formation and ultimate globe salvage.

Objectives

To investigate whether the grade of retinal toxicity post-IVM impacts retinal and seeding tumor recurrence, as well as the overall ability to salvage the eye.

Methods

A single-institution retrospective chart review was performed on 47 eyes of 42 patients who received systemic intravenous chemotherapy followed by IVM as salvage treatment for persistent or recurrent vitreous seeding. Chorioretinal toxicity was graded from 0 to 5.

Results

Toxicity grade was inversely associated with the risk of recurrence, where a one-unit increase in toxicity grade correlated with nearly a 54% reduction in the odds of tumor recurrence (OR 0.46 [0.25-0.84], p = 0.01). Similarly, toxicity grade was related to enucleation, where a one-unit increase in toxicity grade was associated with a 31% reduction in the odds of undergoing enucleation (OR 0.69 [0.40-1.18], p = 0.17).

Conclusions

While retinoblastoma therapy aims to limit toxicity, especially visually significant toxicity, eyes with higher grades of post-IVM toxicity are less likely to have retinal and seeding tumor recurrence.

Outcomes of Group D Retinoblastoma With Resistant Vitreous Seeds After Integration of Intravitreal Chemotherapy to the Treatment Protocol

Introduction: A major therapeutic challenge in the salvage of Group D retinoblastoma eyes is the poor response of vitreous seeds to intravenous chemotherapy. The novel use of intravitreal melphalan has greatly impacted the salvage of such eyes; however, concerns regarding its safety and toxicity still exist, particularly in dark-eyed children. This study aims to evaluate our experience and determine the visual and anatomical outcomes of intravitreal melphalan in group D retinoblastoma with resistant vitreous seeds.

Method: All patients, from August 2018 to February 2020, with group D retinoblastoma harboring vitreous seeds refractory to first-line chemo reduction regimen with vincristine, etoposide, and carboplatin for six cycles plus local consolidation with thermotherapy or cryotherapy were evaluated. Fifteen eyes of 15 patients that fulfilled the eligibility criteria and received intravitreal melphalan were retrospectively reviewed for demographics, iris color, treatments offered, seed inactivation, globe survival, visual acuity, and complications.

Result: Mean age at presentation was 22 months for bilateral disease and 36 months for unilateral disease. A total of 77 injections were administered (mean, five injections per eye) with doses ranging from 20 µg to 30 µg. Complete seed control was seen in 13 of 15 (87%) eyes, and globe salvage was possible in 11 of 15 (73%) eyes. Eyes with macular tumor had visual acuity ranging from 6/36 (0.8) to 6/60 (1.0). SIx of eight eyes (75%) with extra macular tumors had vision 0.4 or better.

Conclusion: Intravitreal melphalan seems like a promising treatment modality in group D retinoblastoma with resistant vitreous seeds having dark eyes. Amblyopia therapy may play an important role in attaining maximal visual benefits in these children.

JQ1, a selective inhibitor of BRD4, suppresses retinoblastoma cell growth by inducing cell cycle arrest and apoptosis

Retinoblastoma (RB) is the most common intraocular cancer in children, and chemotherapy has been the first-line treatment. However, due to the side effects of chemotherapy drugs, novel treatments must be developed. JQ1, a selective inhibitor of BRD4, suppresses cell growth in several cancers in which BRD4 is overexpressed. In the present study, BRD4 was overexpressed in retinoblastoma, and JQ1 effectively inhibited RB cell proliferation and colony formation by inducing cell cycle arrest and promoting apoptosis. Furthermore, the Myc-P21-CDK2 and Myc-cyclinD3/CDK6 pathways were activated in RB cells treated with JQ1, and an animal experiment suggested that JQ1 significantly inhibited tumour growth in vivo. In conclusion, JQ1 may be a potential drug treatment for retinoblastoma.

Secondary intra-arterial chemotherapy and/or intravitreal chemotherapy as salvage treatment for retinoblastoma

PURPOSE

To evaluate the results of secondary intra-arterial chemotherapy (IAC) and/or intravitreal chemotherapy (IVC) as a salvage treatment for retinoblastoma (RB).

MATERIALS AND METHODS

The medical records of 31 (20 male, 11 female) cases (with 38 eyes) who underwent secondary IAC and/or IVC between February 2010 and June 2019 were retrospectively reviewed.

RESULTS

Thirteen (41.9%) cases had unilateral and 18 (58.1%) had bilateral RB. According to the International Classification of RB, 6 (15.8%) eyes had group B, 9 (23.7%) eyes had group C, 16 (42.1%) eyes had group D, and 7 (18.4%) eyes had group E RB at diagnosis. All patients underwent six-cycle intravenous chemotherapy as primary treatment and 8 eyes received external radiotherapy before IAC/IVC. Secondary IAC was performed in 21 (55.3%) eyes, IVC in 10 (26.3%) eyes, and IAC + IVC in 7 (18.4%) eyes. External radiotherapy was applied in 2 (5.3%) eyes after IAC/IVC, one of which was later enucleated. In total, 17 (44.7%) eyes undergoing secondary IAC/IVC treatments were enucleated. Metastasis and death were not observed in any case during the mean follow-up period of 59.3 (median 61, range: 10-98) months.

DISCUSSION

Although 60.5% of the eyes undergoing IAC/IVC consisted of groups D and E RB, globe salvage and survival rates were 55.3% and 100.0%, respectively. External radiotherapy was required in 5.3% of the eyes after IAC/IVC. In conclusion, IAC and IVC are safe and effective treatment methods in eyes with RB unresponsive to other eye-preserving treatments and those demonstrating recurrence.

Development of In Vivo Model of Intraocular Retinoblastoma

Here we describe creation of a model of intraocular retinoblastoma on 4 mature immunodeficient BALB/c nude mice of both sexes. A suspension of the primary retinoblastoma culture was injected into each of the 8 eyes of the test animals. The injections were performed under the control of an operating microscope using insulin syringes with a diameter of 29G transsclerally into the subretinal space in a volume of 0.3 ml at a rate of 10,000 cells in 25 μl physiological saline. The culture of Rb10 cells derived from a patient with retinoblastoma passed 12 passages at the time of the experiments. After 9-week follow-up, a clinical (ophthalmoscopy) and instrumental (ultrasound) study was performed with visualization of the tumor mass on the fundus. After enucleation, a morphological study was performed. The retinoblastoma tumor nodes were identified in two eyes. The proposed model can be used for further research and for testing new chemotherapeutic drugs and treatment regimens for retinoblastoma.

Successful growth of fresh retinoblastoma cells in chorioallantoic membrane

The authors developed a retinoblastoma model using fresh harvested cells from an enucleated eye that were transplanted in chick embryos (chorioallantoic membrane model). The transplanted embryos were treated with escalating doses of Melphalan. This exploratory model was developed with the goal of testing drug sensitivity. Our findings suggest this tumor model could be employed to personalize treatment for patients with retinoblastoma, especially those with bilateral and more refractory disease.

Is intravitreal topotecan toxic to retinal function?

Background

Intravitreal injections of topotecan are used in the management of retinoblastoma with vitreous seeds. This study evaluated whether intravitreal topotecan was associated with retinal toxicity.

Methods

Retrospective cohort study of patients with retinoblastoma who were treated with intravitreal topotecan at Memorial Sloan Kettering Cancer Center between December 2014 and May 2019. Electroretinogram (ERG) responses under anaesthesia were measured immediately before treatment with intravitreal topotecan and at the next visitor approximately one-month. Ocular toxicity was defined by a decrease in the ERG response at 30 Hz at follow-up.

Results

Ocular toxicity was evaluated by ERG on 50 evaluable injections administered to 28 eyes. 22 (44.0%) injections were performed with concurrent intravitreal melphalan. The median time to ERG measurement following an injection was 27 days. By using a paired t-test, intravitreal topotecan combined with melphalan (n=22) at a dose of 25 μg or 30 μg was associated with a significant decrease in ERG amplitude at follow-up (p=0.046, 95% CI −20.4 μV to −0.2 μV). Among eyes that only received topotecan (n=28) at doses of 20 μg or 30 μg, there was not a significant difference in ERG amplitude measured (p=0.85, 95% CI −7.0 μV to 5.8 μV).

Conclusion

Intravitreal topotecan combined with intravitreal melphalan was associated with a decrease in ERG amplitude; there was not a significant decrease in ERG amplitude observed in patients who received topotecan alone. These findings suggest that intravitreal topotecan injections at doses of 20 μg or 30 μg are not associated with retinal toxicity in patients with retinoblastoma.