Comparing efficacy and side effects of two systemic chemotherapy regimens for eye-preserving therapy in children with retinoblastoma

Utility of carboplatin therapeutic drug monitoring for the treatment of neonate and infant retinoblastoma patients in the United Kingdom

BACKGROUND

Retinoblastoma is the most common intra-ocular malignancy in children and frequently presents in very young patients who commonly require intravenous carboplatin. Delivering this is challenging due to a lack of uniform dosing recommendations, rapid changes in physiological function and the risk of side-effects.

METHODS

We conducted a retrospective review of neonates and infants in the UK with retinoblastoma, who have undergone carboplatin therapeutic drug monitoring (TDM). We report on the pharmacokinetic, treatment efficacy and toxicity data.

RESULTS

In total, 29 patients (median age 5 weeks at treatment onset) underwent a total of 74 TDM guided cycles of chemotherapy, involving real time sampling and dose adjustment. An additional 13 patients underwent TDM sampling to modify doses between cycles. Without the adoption of TDM guided dosing, carboplatin exposures would have been ≥20% outside the target AUC in 38/78 (49%) of treatment cycles. Excellent responses and a reassuringly low incidence of toxicities were observed following dose adjustment, despite the young patient age and the implementation of dose increases in the majority of cases.

CONCLUSIONS

Real time TDM is safe, effective and deliverable for neonates and infants receiving carboplatin for retinoblastoma and should be considered standard of care up to the age of 6 months.

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

Background

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

Summary

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

Key Messages

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

Pediatric oncology drug development and dosage optimization

Oncology drug discovery and development has always been an area facing many challenges. Phase 1 oncology studies are typically small, open-label, sequential studies enrolling a small sample of adult patients (i.e., 3-6 patients/cohort) in dose escalation. Pediatric evaluations typically lag behind the adult development program. The pediatric starting dose is traditionally referenced on the recommended phase 2 dose in adults with the incorporation of body size scaling. The size of the study is also small and dependent upon the prevalence of the disease in the pediatric population. Similar to adult development, the dose is escalated or de-escalated until reaching the maximum tolerated dose (MTD) that also provides desired biological activities or efficacy. The escalation steps and identification of MTD are often rule-based and do not incorporate all the available information, such as pharmacokinetic (PK), pharmacodynamic (PD), tolerability and efficacy data. Therefore, it is doubtful if the MTD approach is optimal to determine the dosage. Hence, it is important to evaluate whether there is an optimal dosage below the MTD, especially considering the emerging complexity of combination therapies and the long-term tolerability and safety of the treatments. Identification of an optimal dosage is also vital not only for adult patients but for pediatric populations as well. Dosage-finding is much more challenging for pediatric populations due to the limited patient population and differences among the pediatric age range in terms of maturation and ontogeny that could impact PK. Many sponsors defer the pediatric strategy as they are often perplexed by the challenges presented by pediatric oncology drug development (model of action relevancy to pediatric population, budget, timeline and regulatory requirements). This leads to a limited number of approved drugs for pediatric oncology patients. This review article provides the current regulatory landscape, incentives and how they impact pediatric drug discovery and development. We also consider different pediatric cancers and potential clinical trial challenges/opportunities when designing pediatric clinical trials. An outline of how quantitative methods such as pharmacometrics/modelling & simulation can support the dosage-finding and justification is also included. Finally, we provide some reflections that we consider helpful to accelerate pediatric drug discovery and development.

Long non-coding RNAs involved in retinoblastoma

INTRODUCTION

Retinoblastoma (RB) is the most common childhood tumor that can occur in the retina and develop in a sporadic or heritable form. Although various traditional treatment options have been used for patients with RB, identifying novel strategies for childhood cancers is necessary.

MATERIAL AND METHODS

Recently, molecular-based targeted therapies have opened a greater therapeutic window for RB. Long non-coding RNAs (lncRNAs) presented a potential role as a biomarker for the detection of RB in various stages.

CONCLUSION

LncRNAs by targeting several miRNA/transcription factors play critical roles in the stimulation or suppression of RB. In this review, we summarized recent progress on the functions of tumor suppressors or oncogenes lncRNAs in RB.