ID #524 MEK-inhibitors vs chemotherapy according to SIOP-LGG2004 protocol: visual, tomographic and clinical findings in pediatric optic pathway glioma

Abstract

The SIOP-LGG 2004 chemotherapy is the standard first-line treatment for symptomatic or progressive Optic Pathway Gliomas (OPGs). MEK inhibitors (MEKi) have emerged as a promising alternative, though data on optical coherence tomography (OCT) outcomes in MEKi-treated OPG patients are limited. This study aimed to compare visual and clinical outcomes in children treated with MEKi versus the SIOP-LGG 2004 protocol, highlighting data on peripapillary retinal nerve fiber layer (pRNFL) thickness. Methods This retrospective observational study included 26 eyes of 15 children with OPG treated at Bambino Gesù Children’s Hospital. Patients were divided into MEKi and SIOP- LGG 2004 protocol groups. Clinical, OCT and MRI data were collected at baseline, 12 and 18-months. Results Patients had a mean age of 62.73 months (range 8-208; SD: 51.16). Seven (46.67%) received chemotherapy, while eight (53.33%) received MEKi after progression on chemotherapy. We found no significant differences at baseline between the two groups (p > 0.05) regarding pRNFL, visual acuity (VA) and best response to treatment measured through Response Assessment in pediatric Neuro-Oncology (RAPNO) score. After 18 months, the MEKi group showed better VA (p = 0.038), with stable pRNFL in both groups. MEKi-treated patients had fewer and milder side effects, while all chemotherapy patients experienced toxicity, with three presenting allergic reaction to carboplatin. Conclusions MEKi obtained better VA outcomes and lower toxicity than chemotherapy, with stable pRNFL in both groups, supporting MEKi as an alternative useful treatment option for pediatric OPGs.