Chemotherapy for retinoblastoma: a current topic

Recent progress in retinoblastoma: Pathogenesis, presentation, diagnosis and management

Retinoblastoma, the primary ocular malignancy in pediatric patients, poses a substantial threat to mortality without prompt and effective management. The prognosis for survival and preservation of visual acuity hinges upon the disease severity at the time of initial diagnosis. Notably, retinoblastoma has played a crucial role in unraveling the genetic foundations of oncogenesis. The process of tumorigenesis commonly begins with the occurrence of biallelic mutation in the RB1 tumor suppressor gene, which is then followed by a cascade of genetic and epigenetic alterations that correspond to the clinical stage and pathological features of the tumor. The RB1 gene, recognized as a tumor suppressor, encodes the retinoblastoma protein, which plays a vital role in governing cellular replication through interactions with E2F transcription factors and chromatin remodeling proteins. The diagnosis and treatment of retinoblastoma necessitate consideration of numerous factors, including disease staging, germline mutation status, family psychosocial factors, and the resources available within the institution. This review has systematically compiled and categorized the latest developments in the diagnosis and treatment of retinoblastoma which enhanced the quality of care for this pediatric malignancy.

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

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

In vivo intraocular distribution and safety of periocular nanoparticle carboplatin for treatment of advanced retinoblastoma in humans

PURPOSE

To study the intraocular distribution and safety of polymethylmethacrylate nanoparticles loaded with carboplatin after posterior subtenon injection in humans.

DESIGN

Prospective, interventional, comparative case series.

METHODS

Six patients (mean age: 26.83 ± 7.5 years), scheduled to undergo planned uniocular enucleation in an institutional setting, were randomly divided into 3 groups. Each group received a 10 mg/mL posterior subtenon injection of nanoparticle carboplatin in the eye to be enucleated. Two eyes were enucleated 6, 24 and 72 hours post injection. Intravenous blood was collected during enucleation. The concentration of carboplatin reaching various intraocular tissues was determined by inductively coupled plasma atomic emission spectroscopy. The drug toxicity in the ocular tissues was assessed by histopathology and high-resolution transmission electron microscopy.

RESULTS

The highest level of carboplatin was detected in retinas (8.33 ± 1.69 mg/g), up to 24 hours post treatment. The intravitreal concentration continued to increase gradually until 72 hours (3.46 ± 0.26 mg/g). The choroids and lenses showed very low levels of carboplatin after 6 hours, with negligible amounts at 72 hours. No signs of tissue damage were observed on histopathology or electron microscopy. Intravenous concentration of carboplatin was undetectable in all patients.

CONCLUSION

Results may indicate an increased facilitated trans-scleral transport of nanoparticle carboplatin, with a sustained-release behavior but without any associated short-term ocular or systemic side effects in humans. The very high concentrations achieved in vitreous and retina after a single posterior subtenon injection may be clinically useful for adjunctive treatment of advanced intraocular retinoblastoma with vitreous seeds. However, further studies are needed to assess long-term toxicity and clinical efficacy.

The addition of ifosfamide/etoposide to cisplatin/teniposide improves the survival of children with retinoblastoma and orbital involvement

This study aimed to determine the impact of the addition of ifosfamide/etoposide to a regimen containing cisplatin/teniposide on the survival of patients with retinoblastoma with orbital involvement. Thirty patients were treated at the A. C. Camargo Hospital, Brazil, from 1986 to 2002. From 1986 to April 1992 (period I, n=12), treatment consisted of 3 cycles of induction chemotherapy with cisplatin and teniposide, followed by maintenance with same drugs alternating with cyclophosphamide, vincristine, and doxorubicin every 21 days for 60 weeks. Since April 1992 (period II, n=18), the treatment consisted of 3 cycles of ifosfamide and etoposide followed by maintenance with same drugs, alternating with cisplatin and teniposide every 21 days for 36 weeks. In both periods, children were submitted to exenteration with eyelid preservation and orbital radiation therapy with 45 cGy, and also received intrathecal therapy with methotrexate plus dexamethasone and cytarabine. Kaplan-Meier method was used for survival analysis. The median age was 31 months. Most patients (86.7%) presented unilateral tumors. The 3-year overall survival was 34.4% and 72.2%, respectively, for patients treated during periods I and II (P=0.061). The addition of ifosfamide/etoposide to chemotherapy with cisplatin/teniposide improves survival in these patients, but further studies are still necessary.

Clinical and epidemiological characteristics of retinoblastoma: correlation with prognosis in a Turkish pediatric oncology center

Advanced intraocular tumors and metastatic disease in retinoblastoma patients still occur frequently in developing countries. The aim of this retrospective study was to describe the clinical and epidemiological characteristics of patients with retinoblastoma and the effects of these features on disease prognosis in the authors' pediatric oncology unit as a developing country profile to define the problem. A retrospective chart review of 91 patients who presented to the unit between May 1996 and December 2003 was conducted in this study. Patients with unilateral disease presented at a median age of 24 months and those with bilateral disease at a median age of 9.5 months (p < .01). Most of the eyes with retinoblastoma (68.6%) had Reese-Ellsworth stage V disease. Metastatic disease was diagnosed in 19 (20.9%) patients. Cases with metastatic disease presented at a median age of 24 months and those without metastatic disease at a median age of 12.5 months (p < .05). In 31 patients (34.1%) there was a delay in diagnosis. The enucleation ratio in eyes with advanced intraocular stage was significantly higher than in eyes with early intraocular stage (57.9 vs. 3.8%) (p < .001). In patients with metastatic disease, tumor recurrence was more frequent than in the nonmetastatic patients (36.8 vs. 4.2%) (p < .01). Seven children (7.7%) died due to central nervous system (CNS) metastasis (p < .01). Advanced intraocular disease and distant metastases occur more frequently in Turkish children with retinoblastoma than in children in developed countries, causing a higher rate of enucleation and mortality. Late referral might account for the delayed diagnosis.

Survival in extra-orbital metastatic retinoblastoma:treatment results

INTRODUCTION

Retinoblastoma (RB) is the most frequent malignant eye tumor in childhood. In developing countries advanced stages are common. The purpose of this paper is to present our 21-year clinical experience with metastatic extra ocular RB patients treated with 5 different chemotherapy schemas at a single Mexican Pediatric referral center.

MATERIALS AND METHODS

A retrospective analysis was carried out reviewing the clinical characteristics of patients with metastatic RB. The information analyzed included the delay in diagnosis after first symptoms, age, sex, ocular staging, and anatomic site of metastases, treatment scheme, initial response and status at the last contact or date of death.

RESULTS

Eighty-one patients were included; age range was from 3 to 80 months. The most common site of metastasis was central nervous system (83.9%). From those patients treated with chemotherapy (n = 74), 89.2% presented a complete initial response (n = 66). Early mortality occurred in 7 cases before any treatment. Fifty-six received treatment and died with progressive disease. All patients without radiotherapy died with tumor activity (n = 15). The use of cisplatin was related with longer disease free intervals; no other variable was related with survival. Four patients were alive and disease free at 33 to 144.3 months of follow up from diagnosis. The prevalent cause of death was tumor progression.

CONCLUSIONS

In our experience, metastatic RB has a very high mortality rate in spite of the use of different chemotherapy regimens.

Expression and amplification of therapeutic target genes in retinoblastoma

PURPOSE

We set out to evaluate alterations of the therapeutic target genes KIT (CD 117), EGFR, and HER-2 in human retinoblastoma.

METHODS

Ninety-five formalin-fixed, paraffin-embedded retinoblastomas were brought into a tissue microarray (TMA) format. Immunohistochemistry was performed to analyze the expression of CD117, EGFR, and HER-2. Fluorescence in situ hybridization (FISH) was utilized for detection of EGFR amplifications. Three tumors with strong CD117 positivity were sequenced for KIT exon 11 mutations.

RESULTS

Detectable CD117 expression was seen in 19% of all interpretable cases. Sequence analysis of the three tumors with the strongest CD117 expression revealed no mutations. EGFR was positive in 14% of all cases. No EGFR amplification was observed by FISH, however. All tumors were negative for HER-2 expression.

CONCLUSIONS

Our data suggest that selected cases of retinoblastoma may be candidates for anti-EGFR and imatinib mesylate (STI571) therapy.

The chemosensitivity profile of retinoblastoma

Retinoblastoma is a rare malignant tumour of the developing retina with an incidence of 1 in 20,000 live births in all human races. Chemotherapy is used in retinoblastoma as adjuvant therapy to prevent the growth of metastases and to treat metastatic disease once this has become clinically apparent. Current regimens are based on empirical drug combinations, and few clinical trials have been conducted because of the rarity of this tumour. Chemosensitivity testing offers a way of testing a large number of agents against tumours. The ATP-based chemosensitivity assay (ATP-TCA) has already helped to design new regimens for melanoma and breast and ovarian cancer. Primary retinoblastoma tumour material was obtained from 10 eyes, 7 of which contained sufficient viable cells for ATP-TCA. The results show very high sensitivity to single agents, particularly cisplatin, doxorubicin and vinca aLkaloids. Of the anti-metabolites tested, 5-FU is relatively disappointing (although still active), and gemcitabine shows considerable activity consistent with a cytotoxic effect. The shape of the inhibition curves is interesting. There is a plateau effect with the topoisomerase inhibitors and vinblastine, which is not present with the cisplatin. One tumour was much more resistant than the others tested, particularly to vinblastine but also to the topoisomerase inhibitors, which failed to achieve complete kill at any concentration tested, consistent with a multidrug resistance phenotype. Of the combinations (VAC and VEC), the VAC regimen looks marginally more active in the more resistant of the two cases tested to date. These data confirm that retinoblastoma is a rapidly growing malignancy that is very susceptible to cytotoxic drugs of all types. Chemosensitivity testing provides a practical method of testing new regimens before clinical trials in retinoblastoma patients.

Topical cyclosporine in pediatric keratoplasty

PURPOSE

To evaluate the efficacy and safety of combined treatment with 2% topical cyclosporine (CsA) and topical corticosteroid compared to treatment with topical corticosteroids only after pediatric keratoplasty.

METHODS

Twenty-two grafts in 16 pediatric patients were evaluated retrospectively. The eyes were divided into a CsA group (9 eyes) and a control group (13 eyes) based on the postoperative treatment regimen. Information reviewed included patient age and sex, clinical diagnosis; preoperative and postoperative intraocular pressure and lens status; previous, concurrent, and subsequent surgical procedures; operative and postoperative complications; number of graft rejections, timing of suture removal, and length of follow-up. The clinical outcome of penetrating keratoplasty (PK) was evaluated by the rate of rejection-free graft survival and graft survival evaluation by the Kaplan-Meier log-rank test.

RESULTS

The rejection-free graft survival rate was 88.9% in the CsA group and 38.5% in the control group. This difference in rejection-free graft survival rate between the groups was statistically significant (P =.0465). The graft survival rate was 88.9% in the CsA group and 46.2% in the control group. The difference in the graft survival rate was not statistically significant between the groups (P =.6). No clinical signs of systemic or local toxicity were seen with the topical CsA treatment.

CONCLUSIONS

Two percent topical CsA is safe and effective in reducing the risk of allograft rejection in pediatric recipients.

Current treatment of retinoblastoma

Chemotherapy has recently achieved a major role in the primary management of intraocular retinoblastoma. Tumor reduction by first-line chemotherapy (chemoreduction) followed by local treatments is now accepted as treatment strategy for intraocular retinoblastoma with the goal of avoiding external beam radiotherapy (EBRT) or enucleation. Although efficient in reducing tumor volume, chemotherapy cannot cure retinoblastoma. Different chemoreduction protocols are used to shrink the tumor, making it treatable with cryotherapy, laser photocoagulation, thermotherapy, and plaque radiotherapy. Systemic chemotherapy used with local ophthalmic therapies during or after the chemotherapy can eliminate the need for enucleation or external beam radiotherapy in Reese-Ellsworth group 1, 2, or 3 retinoblastoma. This combination is not sufficient to obtain tumor control in most eyes with large tumors and diffuse vitreous and subretinal seeds (Reese-Ellsworth group 4 and 5 tumors), and EBRT or enucleation is eventually required. The resultant visual acuity after globe-conserving therapies in those eyes with Reese-Ellsworth group 4 and 5 tumors is often poor. Preliminary results of a phase I/II study of subconjunctival carboplatin injection are encouraging. Enucleation is still recommended in situations such as eyes containing large tumors, long standing retinal detachment, neovascular glaucoma, pars plana tumor seeding, anterior chamber involvement or choroid, optic nerve or orbital tumor extension, and no expectation for useful vision. Chemoprophylaxis is necessary for patients with tumor extending to the surgical margin of the optic nerve and is likely beneficial in preventing metastases in patients with tumor extending beyond the lamina cribrosa. Intensified chemotherapy with autologous stem cell rescue appears effective for patients with metastatic retinoblastoma.

Three dimensional ultrasound of retinoblastoma: initial experience

AIM

To use 3D ultrasonography (3DUS) for the diagnosis of retinoblastoma.

METHODS

Five eyes of three children with retinoblastoma were evaluated using a commercially available computerised 3DUS system. Interactive sectioning of the stored and reconstructed 3D volumes were performed. 3DUS and histopathological findings were correlated after enucleation.

RESULTS

3DUS examination revealed characteristics consistent with retinoblastoma: endophytic mass, retinal detachment, intratumoural calcifications, and secondary orbital shadowing. Unlike 2D imaging, 3DUS allowed for analysis of the acquired and stored volumes. Rotation and sectioning of this volume allowed the discovery of new oblique and coronal views. For example, calcium related orbital shadows were seen as 3D volumes and (coronal) cross sections of the optic nerve were evaluated for evidence of intraneural invasion by retinoblastoma.

CONCLUSION

This is the first reported series of patients examined with 3DUS imaging for retinoblastoma. This technique allowed for new oblique and coronal views of the tumour and optic nerve. The ability to retrospectively analyse the (scanned and stored) ocular volume facilitated patient care, teaching, tumour-volume analysis, and telemedicine.

Risk factors for metastasis in retinoblastoma

Children with retinoblastoma typically survive their cancer due to advances in early diagnosis and treatment. Despite this success, risk factors persist for metastasis that are thought to be related to patient age, sex, laterality, treatment, genetics, histopathology, and extraocular extension. This review has found that invasion of the uvea, orbit, and optic nerve continue to be the most important predictors of metastatic retinoblastoma. Bilaterality and delays in diagnosis are also important factors. We examine molecular and genetic studies that offer the potential of predicting which tumors are likely to metastasize, which will recur within the eye, and which will undergo senescence. In this review, we describe which clinical evaluations, genetic studies, and histopathologic evaluations of retrieved specimens are currently used widely. This review has been performed to help those caring for patients with retinoblastoma and to aid informed consent.

Chemotherapy for eye cancer

Chemotherapy has been used to treat a multitude of eye cancers. We attempted to review the role of chemotherapy in the treatment of ocular, adnexal, and orbital malignancies by conducting an extensive search of the medical literature. Unfortunately, the published reports typically contain few patients with limited follow-up, precluding definitive recommendations. For most eye cancers, multicenter trials will offer the potential to gather the numbers of patients required to determine the clinical utility of chemotherapy.