Seeds In Retinoblastoma Research Articles

Intravitreal Topotecan for Vitreous Seeds in Retinoblastoma: A Long-term Review of 91 Eyes

To study the long-term efficacy of intravitreal topotecan (IVT) for vitreous seeds in eyes with retinoblastoma and risk factors for their recurrence. Retrospective, non-comparative, interventional study. Ninety-one eyes of 90 patients with retinoblastoma treated between January 2013 and April2019. Patients with recurrent or refractory vitreous seeds after completion of intravenous or intra-arterial chemotherapy were treated with IVT (30 μg/0.15 ml) by the safety-enhanced technique. The injection was repeated every 4 weeks until the regression of seeds. Patients with a minimum follow-up of 12 months were included in the analysis. Primary outcome measures were vitreous seed regression and eye salvage. Secondary outcomes were risk factors for vitreous seed recurrence after treatment with IVT, vision salvage, and complications of IVT. The median age of the patients was 18 months, with most having group D (n= 58 [64%]) and group E (n= 26 [29%]) retinoblastoma. Vitreous seeds were refractory in 46 eyes (51%) and recurrent in 45 eyes (49%). A total of 317 IVT injections were administered, with the median being 3 injections. The median number of IVT injections required was 2.5 injections for dust, 3 injections for sphere, and 5 injections for cloud morphologic features. Recurrence of vitreous seeds after IVT was seen in 17 eyes (19%) at a mean follow-up of 7.9 months. At a mean follow-up 34 months, vitreous seed regression was achieved in 88 eyes (97%) and eye salvage was achieved in 77 eyes (85%). Older age (P= 0.018) and recurrence of retinal tumor (15/17 eyes; P < 0.01) significantly increased the risk of vitreous seed recurrence. Cataract was the most common complication seen in 17 eyes (9%). Intravitreal topotecan at an every 3- to 4-week regimen is effective against both refractory and recurrent vitreous seeds. The vitreous seed morphologic features correspond to the number of injections required for regression. Increasing age and recurrence of retinal tumor increase the risk of vitreous seed recurrence after treatment with IVT. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Addition of intravitreal carboplatin with melphalan for management of vitreous seeding in retinoblastoma.

To evaluate the efficacy and toxicity of intravitreal carboplatin plus melphalan for the treatment of vitreous seeds in eyes with retinoblastoma (RB). This retrospective series at a tertiary referral center included 22 consecutive RB patients who had received intravitreal carboplatin (16μg per 0.05ml) combined with melphalan (30μg in 0.03ml) [IVi (Ca-Me)] for treatment of vitreous seeds. Tumor control and drug toxicities were recorded. There were 22 eyes of 22 patients, divided into primary group (n = 13) without history of previous intravitreal chemotherapy (IViC) and refractory group (n = 9) with history of previous IViC using melphalan and/or topotecan. The demographics and clinical findings of the primary and refractory groups did not differ significantly. The 6-month follow-up revealed complete vitreous seed control (77% vs. 89%, p = 0.47). Vitreous seed recurrence was detected in 1 eye of each group at 6months. During the next 18-month follow-up period, no recurrence of seed was observed. The response to IVi (Ca-Me) was not significantly influenced by previous IViC (p = 0.70), primary systemic or intra-arterial chemotherapy (p = 0.45), or the type of regression (p = 0.35). The most common tumor treatment complications were retinal detachment (RD) (n = 2), early hypotony (n = 2) and late hypotony (n = 4, unrelated), cataract (n = 2), and severe pigment dispersion (n = 1). Enucleation was performed in 8 eyes, for total RD (n = 1), phthisis bulbi (n = 5), and extensive solid tumor recurrence (n = 2). There was no case of orbital invasion, systemic metastasis, or death. Based on this interventional case series for primary and refractory vitreous RB seeds, carboplatin plus melphalan therapy may be effective with few toxic side effects.

Abstract 6052: Single cell profiling of vitreous humor seeds in retinoblastoma

Abstract Purpose: Previous studies of retinoblastoma (RB) aqueous humor (AH) analysis for tumor-derived cell-free DNA (cfDNA) have shown that the somatic copy number alteration (SCNA) profiles derived from the AH are highly concordant to profiles derived from the tumor in most but not all cases. As one of the reasons for the discordance in certain cases, it was suggested that these patients had multiple retinal tumors that had developed different subsets of SCNAs. The AH was therefore speculated to be a heterogenous mixture of cfDNA from each tumor clone, a heterogeneity that could not be captured in a single tumor biopsy after enucleation. In such cases that do not show high concordance, analyzing the genomic profile of tumor seeds in the VH can help us determine the degree of heterogeneity between the different subclones in the tumor. As single tumor cells from the vitreous humor (VH) have not been studied in RB before, this study demonstrates a technique that could be used to investigate the SCNA profiles of these cells with the aim to further understand the possible origins of AH cfDNA. Methods: The subject of this study is a 24-month-old male diagnosed with advanced unilateral RB (Group D/Stage CT2B) in the left eye and treated with primary enucleation after seven days. VH was collected from the enucleated eye, cfDNA was isolated from the AH and VH, and tumor DNA was extracted from tumor biopsy. Thirty live VH single cells were isolated using fluorescence-activated cell sorting using DAPI staining. The cells were then amplified using GenomePlex® Single Cell Whole Genome Amplification Kit (WGA4). Tumor DNA and single-cell WGA amplicons were constructed using NEBNext Ultra II FS Kit, and whole genome libraries of cfDNA from AH and VH were constructed using QIAseq Ultralow Input Library Kit. Shallow WGS of these libraries were sequenced using the IIlumina paired-end (2 X 150bp) platform to assess genome-wide SCNAs. Heatmap with hierarchical clustering was generated in R using the heatmap.2 function in the ggplots package. Cells were clustered by Ward’s method with Manhattan distance by their median centered data. Cutoffs for gains and losses were 1.2 and 0.8 over the median respectively. Results: There was high concordance in SCNA profiles across AH cfDNA, VH cfDNA, and tumor DNA, showing highly recurrent RB SCNAs such as gains on 1q, 2p, and 6p, in addition to gains on 2p, 5p, 7q, 9q, 10q, 13q, 15q, 17q and loss on 3q. The SCNA profiles of the 30 VH seeds demonstrated the highly recurrent RB SCNAs (gains on 1q, 2p, and 6p) that were consistent with the tumor SCNA signature. The heatmap of the VH single cell SCNA profiles demonstrated low levels of heterogeneity between the seeds. Conclusions: Our results suggest that VH seeds are tumor cells. Analyzing genomic material of the VH seeds using single cell SCNA profiling provides a valuable platform to study tumor heterogeneity in RB. Citation Format: Shreya Sirivolu, Liya Xu, Peter Kuhn, James Hicks, Jesse Berry. Single cell profiling of vitreous humor seeds in retinoblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6052.

Aqueous Seeding in Retinoblastoma: Classification and Clinicopathologic Correlation

To correlate the clinical types of aqueous seeds with histopathologic characteristics in primarily enucleated eyes with retinoblastoma (RB). Retrospective study. Twenty-five patients with RB. Clinicopathologic correlation of aqueous seeds in 25 eyes that underwent primary enucleation and showed evidence of aqueous seeds. Histopathologic characteristics of aqueous seeds. All 25 enucleated eyes were classified as group E RB based on the International Classification of Intraocular Retinoblastoma. Clinically, type 1 aqueous seeds were noted in 9 (36%) eyes, type 2 in 8 (32%), and type 3 in 8 (32%). Based on histopathology, type 1 seeds were defined as individual tumor cells admixed with macrophages and nonviable tumor cells. Type 2 seeds were defined as spheres and classified into 2 subtypes: (1) spheres without central necrosis containing solid clusters of tumor cells and (2) spheres with central necrosis containing a central core of necrotic cells surrounded by viable tumor cells. Type 3 seeds were defined as tumor cells admixed with macrophages and red blood cells sedimented at an angle. Aqueous seeding involved both anterior (n= 25; 100%) and posterior (n= 18; 72%) chambers. Significant infiltration of RB into the intraocular tissue (Schlemm canal, trabecular meshwork, ciliary body, choroid, optic nerve, and sclera) was noted in 23 cases (92%). Compared with eyes with type 1 and 2 seeds, eyes with type 3 seeds were more commonly associated with ciliary body infiltration (41% vs. 88%, respectively; P= 0.04). Over a mean follow-up period of 57months (median, 49 months; range, <1-175 months), metastasis and death were noted in 3 patients (12%). Similar to vitreous seeds in RB, aqueous seeds have 3 distinct histopathologic types. Posterior chamber seeds were noted in 72% of cases presenting with anterior chamber (AC) seeds, indicating the need for the treatment of both the chambers whenever conservative treatment is attempted in suitable cases. Most (92%) cases with primary aqueous seeding are associated with other high-risk histopathology features, suggesting acautious approach to conservative management in these cases.

Less is more: new one-step intracameral chemotherapy technique.

Purpose: To describe the feasibility of a new one-step approach to aspirate the aqueous and apply melphalan in a single-go without repeated entries into the anterior chamber.Methods: This retrospective non-comparative study was conducted at a referral center and included 12 patients. The one-step approach is described in a step-wise manner. No complications were observed among the patients.Results: One single injection of intracameral melphalan proved to be a successful treatment in nine cases. Two patients required a second injection, which was administered two weeks after the first one following the same technique.Conclusions: This proved to be a reasonable technique for the smooth application of melphalan in the anterior chamber studded with retinoblastoma seeds. Our outcomes revealed that it is an effective, quick, and cost-effective technique. Longer-term data collection is underway, though initial findings are encouraging.

Retinoblastoma seeds: impact on American Joint Committee on Cancer clinical staging

AimTo investigate whether the American Joint Committee on Cancer (AJCC) clinical category cT2b needs to be subclassified by the type and distribution of retinoblastoma (RB) seeding.MethodsMulticentre, international registry-based data were...

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.

Pathologic evidence of retinoblastoma seeds supported by field emission scanning electron microscopy and Raman spectroscopy.

Purpose:The aim of this study was to examine the pathology of retinoblastoma (RB) seeds with supportive evidence by field emission scanning electron microscopy and Raman spectroscopy.Methods:This study was a laboratory-based observational study. Enucleated eyeballs received in the ocular pathology department of a tertiary eye care center in northeast India were included in the cohort after obtaining written informed consent during the surgery. The study was carried out for 6 years (2015–2020). Most of the eyeballs were Group-E RBs. Standard eyeballs sectioning were done by bread loaf techniques. Gross documentations included RB seeds seen in the smallest calotte done with utmost care. Seeds were documented also in permanent sections. Scanning electron microscopy and Raman spectroscopy were carried out in an index case.Results:Out of the total 59 cases, 35 RB cases had different seedings. The mean age at enucleation was 2.9 years. RB seeds were seen in vitreous (n = 19), subretinal plus vitreous (n = 7), anterior chamber (n = 1), over crystalline lens (n = 3), retinal surface (n = 1), retinal pigment epithelium (RPE; n = 2), subretinal (n = 1), calcified seeds (n = 2). Other characteristics were dusts (n = 7), clouds (n = 11), spheres (n = 4), and unspecified type (n = 13). Histopathological high-risk factors showed significant choroidal (n = 22) and optic nerve (n = 15) involvement. Few cases had extraocular spread. Undifferentiated tumor (n = 24) was seen with higher evidence of necrosis (n = 23). Raman spectra differentiated the seeds from the normal tissue on the basis of lipid and protein content.Conclusion:This study highlights the different types of RB seeds with high-risk factors. The morphology of those seeds showed the difference between vitreous and subretinal seeds under advanced microscopic observations.

Outcomes of intravitreal melphalan for vitreous seedings in retinoblastoma resistant to systemic chemotherapy

PurposeTo determine the efficacy of intravitreal injection of melphalan for vitreous seedings resistant to systemic chemotherapy. Methods and materialProspective non comparative study investigates 105 consecutive eyes of 105 retinoblastoma patients in a tertiary care hospital. Patients with persistent or recurrent vitreous seeds were included in the study. Injection melphalan was prepared under aseptic conditions. Injection was given at 2–4 mm away from the limbus using 27gauge needle. Cryotherapy was applied at injection site before and during removal of needle. Eye was copiously irrigated soon after the injection to minimize the chances of surface toxicity. After injection intravitreal melphalan, eye pad was applied for 2 h and patients were instructed to instill topical antibiotic and steroid drops for one week. Patients were examined the next day and then weekly till 3rd week. At each follow up, examination under microscope (EUA) and indirect ophthalmoscopy was done. Retinal images were taken using retcam MII for comparison with the previous ones. ResultsTwenty-five (23.8%) out of 105 eyes showed complete regression of vitreous seeds with one injection of intravitreal melphalan after one month. Thirty-one (29.5%) eyes required further 3 intravitreal injections for complete regression, while thirty-four (32.4%) eyes required further 6 intravitreal injections for complete regression. Fifteen (14.3%) eyes did not show regression of vitreous seeds even after 6 intravitreal injections and were planned for second line chemotherapy. ConclusionIntravitreal injection melphalan shows promising results in the treatment of vitreous seeds in retinoblastoma, resistant to systemic chemotherapy.

Intravitreal melphalan therapy for vitreous seeds in retinoblastoma: Implementation and outcomes of a new chemotherapy protocol.

Retinoblastoma is the most common paediatric ocular tumour, which appears in the retina. Without treatment, retinoblastoma grows and destroys the internal ocular globe architecture, even leading to metastasis. When treated, overall survival is close to 97%, the alkylating drug melphalan being the most extensively used chemotherapeutic agent in localised treatment. The aim of this study is to describe the implementation of a new intravitreal chemotherapy retinoblastoma treatment protocol for children implanting vitreous seeds through intravitreal melphalan injections and to evaluate the patients' health outcomes treated with it. Between December 2014 and July 2018, seven patients were treated with this protocol. They received a mean of 3.3 cycles of intravitreal melphalan with standard doses of 30 mcg per cycle. In the seven eyes treated in our hospital, the response was as expected; three eyes with vitreous seedings (43%) were successfully treated. The main adverse effects presented by all patients were scars at cryogenisation points. In two patients, the appearance of 'salt and pepper' retinopathy was reported. Oncology pharmacists, as part of the treatment team, can provide information about recommended doses, expected adverse effects, stability of preparations, most appropriate method of processing, packaging, and methods of drug administration, to ensure efficacy and especially safety in the administration of these drugs.

Intravitreal topotecan in the management of refractory and recurrent vitreous seeds in retinoblastoma

Background/aimTo evaluate the efficacy of intravitreal topotecan for refractory or recurrent vitreous seeds in retinoblastoma.MethodsIntravitreal injection of topotecan hydrochloride (30 µg/0.15 mL) was provided every 3 weeks by the safety...

Vitreous Seeds in Retinoblastoma: Clinicopathologic Classification and Correlation

A recent classification scheme for retinoblastoma vitreous seeds has shown promise in predicting treatment response. For the first time, we correlate this clinical classification scheme with its histopathologic features. Retrospective review. Enucleated eyes received at the pathology department of the Retinoblastoma Center of Houston from 2010 to2015. Macroscopic photographs of the enucleated eyes of patients with retinoblastoma were analyzed to select those with vitreous seeds. Cases with adequate material for clinicopathologic correlation were selected for further analysis, and clinical photographs were reviewed. Routine histopathologic slides were reviewed and compared with the clinical and macroscopic photographs. Seeds were classified as type 1 ("dust"), type 2 ("sphere"), or type 3 ("cloud"). To confirm the presence of macrophages, CD68 immunohistochemical staining was used. Synaptophysin was used to stain retinoblastoma cells. To correlate clinical vitreous seed type with histopathologic features. A total of 14 eyes with adequate amounts of tumor seeds along with clinical and macroscopic photographic correlation were selected from a total of 138 eyes reviewed. Type 1 seeds consisted of individual viable tumor cells and scattered macrophages. Type 2 seeds consisted of 2 submorphologies: spheres with viable cells throughout and spheres with an outer rim of viable cells but necrotic cells centrally. Type 3 seeds were composed of more than 90% necrotic material admixed with few macrophages and viable cells at their outer rim. Untreated (8/14) and previously treated (6/14) eyes showed similar histopathologic features for each type of seeds. Treated eyes had more type 1 and 3 seeds. We provide the first histopathologic correlation of the clinical classification scheme for vitreous seeds in retinoblastoma. "Dust" is formed by scattered single cells alternating with macrophages. "Spheres" with translucent centers contain multiple layers of viable tumor cells that shed single cells and may be more clinically aggressive. "Cloud" seeds are mostly composed of necrotic material, explaining their lack of therapeutic response. Pretreated eyes showed tumor seeds morphologically similar to untreated eyes. Knowledge of the underlying histopathology of vitreous seed types is a fundamental component of classification and may aid in understanding clinical response to treatment.

Preclinical Acute Ocular Safety Study of Combined Intravitreal Carboplatin and Etoposide Phosphate for Retinoblastoma.

To describe the ocular toxicity of intravitreal carboplatin and etoposide phosphate (VP16P) in Dutch-Belted rabbits. Twenty-two adult male Dutch-Belted rabbits (Cohort 1) each received a single, bilateral intravitreal injection (0.05 mL). For Cohort 1, safety was assessed via electroretinograms (ERGs) and ocular examination. Of nine total groups in Cohort 1, the first five received the following single agents: Group 1: normal saline; Group 2: VP16P 75 µg; Group 3: VP16P 100 µg; Group 4: carboplatin 4 µg; and Group 5: carboplatin 8 µg. Groups 6 through 9 received the following combination of carboplatin/ VP16P, respectively: Group 6: 8 µg/75 µg, Group 7: 8 µg/50 µg, Group 8: 4 µg/50 µg, and Group 9: 2 µg/25 µg. Cohort 2 consisted of 15 Dutch-Belted rabbits in seven groups (Groups 10 through 16), each receiving a single, bilateral intravitreal injection. For Cohort 2, safety was assessed via histopathology. Groups 2 through 8 demonstrated a statistically significant decrease (relative to Group 1) in at least one ERG waveform amplitude obtained 4 weeks postinjection (P < .05). Group 9 (carbo 2 µg/VP16P 25 µg) did not manifest ERG toxicity. Fundoscopic toxicity consisted of slight-to-moderate attenuation of vessels in rabbits receiving doses above carbo 4 µg/VP16P 50 µg. Histopathologic retinal toxicity (Cohort 2) was dose-dependent, ranging from full-thickness atrophy in rabbits receiving the highest dose to normal in rabbits receiving carbo 2 µg/VP16P 25 µg. Combined carboplatin and VP16P may be compatible for intravitreal injection therapy, and a single dose of 2 µg/25 µg appears to be safe in a rabbit model. These agents may be a safer alternative to intravitreal melphalan (Alkeran; GlaxoSmithKline, Brentford, United Kingdom) for the treatment of vitreous seeds in retinoblastoma. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:151-159.].

Classification of Vitreous Seeds in Retinoblastoma: Correlations with Patient, Tumor, and Treatment Characteristics

To evaluate the patient, disease, and tumor characteristics of the 3 morphologically distinct groups of vitreous seeds in retinoblastoma presenting for treatment with ophthalmic artery chemosurgery (OAC): dust (class 1), spheres (class 2), and clouds (class 3) in primary and recurrent vitreous seeds. Retrospective cohort study of patients treated for vitreous seeds at Memorial Sloan Kettering Cancer Center between May 2006 and March2015. A total of 135 eyes with active vitreous seeds, presenting for primary treatment with OAC or with recurrent vitreous disease. Vitreous seeds were classified into 3 groups: dust, spheres, and clouds. Indirect ophthalmoscopy, fundus photography, ultrasonography, and ultrasonic biomicroscopy were used to locate and evaluate the extent of retinal and vitreous disease. Patient and disease characteristics (age, laterality of disease, treatment status) were compared among classification groups. A 2-tailed Fisher exact test and paired Student t test were used for statistical analysis. Age of patient, laterality of disease, location of retinal disease, extent of vitreous disease, and treatment status. Primary treated disease: Patients with eyes containing class 3 (cloud) vitreous seeds were significantly older than patients with class 1 or 2 seeds (P < 0.05). The median age of patients with class 1, 2, and 3 seeds was 11, 15.5, and 32 months, respectively. Eyes containing class 3 seeds were significantly more likely to occur in the equator-ora region of the fundus (P < 0.0001), in a diffuse pattern (P < 0.0001), and in patients with unilateral disease (P < 0.05), compared with class 1 and 2 seeds. Recurrent disease: Recurrent vitreous seeds were significantly more common to class 2 (P < 0.05), occurring in a diffuse pattern (P= 0.01) and in patients with bilateral disease (P < 0.001). The 3 classes of vitreous seeds have distinct clinical characteristics associated with the ageof patient, laterality of disease, and extent and location of tumor-producing seeds. Furthermore, recurrentvitreous seeds appear to have a unique clinical profile compared with seeds receiving primary treatment.

Classification and treatment of vitreous seeds in retinoblastoma using intra-arterial and intravitreal techniques

Classification and treatment of vitreous seeds in retinoblastoma using intra-arterial and intravitreal techniques

The Classification of Vitreous Seeds in Retinoblastoma and Response to Intravitreal Melphalan

To evaluate the clinical characteristics of the 3 classifications of vitreous seeds in retinoblastoma-dust (class 1), spheres (class 2), and clouds (class 3)-and their responses to intravitreal melphalan. Retrospective, bi-institutional cohort study. A total of 87 patient eyes received 475 intravitreal injections of melphalan (median dose, 30 μg) given weekly, a median of 5 times (range, 1-12 times). At presentation, the vitreous seeds were classified into 3 groups: dust, spheres, and clouds. Indirect ophthalmoscopy, fundus photography, ultrasonography, and ultrasonic biomicroscopy were used to evaluate clinical response to weekly intravitreal melphalan injections and time to regression of vitreous seeds. Kaplan-Meier estimates of time to regression and ocular survival, patient survival, and event-free survival (EFS) were calculated and then compared using the Mantel-Cox test of curve. Time to regression of vitreous seeds, patient survival, ocular survival, and EFS. The difference in time to regression was significantly different for the 3 seed classes (P < 0.0001): the median time to regression was 0.6, 1.7, and 7.7 months for dust, spheres, and clouds, respectively. Eyes with dust received significantly fewer injections and a lower median and cumulative dose of melphalan, whereas eyes with clouds received significantly more injections and a higher median and cumulative dose of melphalan. Overall, the 2-year Kaplan-Meier estimates for ocular survival, patient survival, and EFS (related to target seeds) were 90.4% (95% confidence interval [CI], 79.7-95.6), 100%, and 98.5% (95% CI, 90-99.7), respectively. The regression and response of vitreous seeds to intravitreal melphalan are different for each seed classification. The vitreous seed classification can be predictive of time to regression, number, median dose, and cumulative dose of intravitreal melphalan injections required.

Local and Systemic Toxicity of Intravitreal Melphalan for Vitreous Seeding in Retinoblastoma: A Preclinical and Clinical Study

Intravitreal melphalan is emerging as an effective treatment for refractory vitreous seeds in retinoblastoma, but there is limited understanding regarding its toxicity. This study evaluates the retinal and systemic toxicity of intravitreal melphalan in retinoblastoma patients, with preclinical validation in a rabbit model. Clinical and preclinical, prospective, cohort study. In the clinical study, 16 patient eyes received 107 intravitreal injections of 30 μg melphalan given weekly, a median of 6.5 times (range, 5-8). In the animal study, 12 New Zealand/Dutch Belt pigmented rabbits were given 3 weekly injections of 15 μg of intravitreal melphalan or vehicle to the right eye. Electroretinogram (ERG) responses were recorded in both humans and rabbits. For the clinical study, ERG responses were recorded at baseline, immediately before each injection, and at each follow-up visit; 82 of these studies were deemed evaluable. Median follow-up time was 5.2 months (range, 1-11). Complete blood counts (CBCs) were obtained on the day of injection at 46 patient visits. In the animal study, ERG responses were obtained along with fluorescein angiography, CBCs, and melphalan plasma concentration. After humane killing, the histopathology of the eyes was evaluated. For the clinical study, we measured peak-to-peak ERG amplitudes in response to 30-Hz photopic flicker stimulation with comparisons between ERG studies before and after intravitreal melphalan. For the animal study, we collected ERG parameters before and after intravitreal melphalan injections with histopathologic findings. By linear regression analysis, over the course of weekly intravitreal injections in retinoblastoma patients, for every additional injection, the ERG amplitude decreased by approximately 5.8 μV. The ERG remained stable once the treatment course was completed. In retinoblastoma patients, there were no grade 3 or 4 hematologic events. One week after the second injection in rabbits, the a- and b-wave amplitude declined significantly in the melphalan treated eyes compared with vehicle-treated eyes (P<0.05). Histopathology revealed severely atrophic retina. Weekly injections of 30 μg of melphalan can result in a decreased ERG response, which is indicative of retinal toxicity. These findings are confirmed at an equivalent dose in rabbit eyes by ERG measurements and by histopathologic evidence of severe retinal damage. Systemic toxicity with intravitreal melphalan at these doses in humans or rabbits was not detected.

Persistence of retinal function after intravitreal melphalan injection for retinoblastoma

The risk/benefit profile of intravitreal melphalan injection for treatment of active vitreous seeds in retinoblastoma remains uncertain. We report clinical and electroretinography results after 6months of one patient who has shown a favorable initial clinical response to intravitreal melphalan injections for treatment of refractory vitreous seeds. Clinical case report. The patient presented at age 17months with bilateral retinoblastoma [OD: International Classification (ICRB) group E, Reese-Ellsworth (R-E) class Vb; OS: ICRB D, R-E Vb] with no known prior family history. The right eye was enucleated primarily. The patient received systemic chemotherapy and extensive local treatment to the left eye. Ten months later, she presented with recurrent disease, including fine, diffuse vitreous seeds. Tumor control was established with intra-arterial chemotherapy and local treatment. Subsequent recurrence was treated with further intra-arterial chemotherapy, local treatment, and plaque radiotherapy with iodine-125. Persistent free-floating spherical vitreous seeds were treated with 4 cycles of intravitreal melphalan injection via the pars plana, with doses of 30, 30, 30, and 20μg. After 6months of follow-up, the left eye remained free of active tumor. Visual acuity was 20/40. Photopic ERGs amplitudes were unchanged compared with those recorded prior to the intravitreal injection treatments. Intravitreal melphalan injection for refractory spherical vitreous seeds of retinoblastoma with favorable tumor response is compatible with good central visual acuity and preservation of retinal function as indicated by photopic ERG recordings.

Combined intravitreal and subconjunctival carboplatin for retinoblastoma with vitreous seeds

BackgroundTo describe the technique of intravitreal chemotherapy preceded by subconjunctival chemotherapy for the treatment of vitreous seeds in advanced stage retinoblastoma.MethodsThis non-comparative interventional case series retrospectively reviewed the medical records...

Pharmacokinetic analysis of topotecan after intra-vitreal injection. Implications for retinoblastoma treatment

Topotecan is a promising drug with activity against retinoblastoma, however, attaining therapeutic concentrations in the vitreous humor is still a challenge for the treatment of vitreous seeds in retinoblastoma. Our aim was to characterize topotecan pharmacokinetics in vitreous and aqueous humor, and to assess the systemic exposure after intra-vitreal injection in rabbits as an alternative route for maximizing local drug exposure. Anesthetized rabbits were administered intra-vitreal injections of 5 μg of topotecan. Vitreous, aqueous, and blood samples were collected at pre-defined time points. A validated high-performance liquid chromatography assay was used to quantitate topotecan (lactone and carboxylate) concentrations. Topotecan pharmacokinetic parameters were determined in vitreous, aqueous and plasma using a compartmental analysis. Topotecan lactone concentrations in the vitreous of the injected eye were about 8 ng/mL 48 h after drug administration. The median maximum vitreous, aqueous and plasma total topotecan concentrations ( C max) were 5.3, 0.68 and 0.21 μg/mL, respectively. The C max vitreous/aqueous of treated eyes and the C max vitreous/plasma were approximately 8 and 254, respectively. Total topotecan exposure (AUC) in the vitreous of the injected eye was 50 times greater than the total systemic exposure. These findings suggest that intra-vitreal administration of only 5 μg of topotecan reaches significant local levels over an extended period of time while minimizing systemic exposure in the rabbit. Intra-vitreal topotecan administration offers a promising alternative route for enhanced drug exposure in the vitreous humor with potential application for treatment of vitreal seeds in retinoblastoma while avoiding systemic toxicities.