Impact of Bevacizumab on Visual Function, Tumor Size, and Toxicity in Pediatric Progressive Optic Pathway Glioma: A Retrospective Nationwide Multicentre Study

Abstract

Backgrounds: Bevacizumab (BVZ) is used as a subsequent line of treatment for pediatric optic pathway glioma (OPG) in the case of progression. Data on the treatment effect concerning tumor progression and visual function are scarce and nationwide studies are lacking.

Methods: We performed a retrospective, nationwide, multicentre cohort study including all pediatric patients with OPG treated with BVZ in the Netherlands (2009-2021). Progression-free survival, change in visual acuity and visual field, MRI-based radiologic response, and toxicity were evaluated.

Results: In total, 33 pediatric patients with OPG were treated with BVZ (median 12 months). Visual acuity improved in 20.5%, remained stable in 74.4%, and decreased in 5.1% of 39 of all analysed eyes. The monocular visual field improved in 73.1%, remained stable in 15.4%, and decreased in 7.7% of 25 analysed eyes. Radiologic response at the end of therapy showed a partial response in 7 patients (21.9%), minor response in 7 (21.9%), stable disease in 15 (46.9%), and progressive disease in 3 (9.3%). Progression-free survival at 18 and 36 months after the start of BVZ reduced from 70.9% to 38.0%. Toxicity (≥grade 3 CTCAE) during treatment was observed in five patients (15.2%).

Conclusion: Treatment of BVZ in pediatric patients with OPG revealed stabilisation in the majority of patients, but was followed by progression at a later time point in more than 60% of patients. This profile seems relatively acceptable given the benefits of visual field improvement in more than 70% of analysed eyes and visual acuity improvement in more than 20% of eyes at the cessation of BVZ.

Keywords: bevacizumab; child; low grade glioma; optic pathway glioma; progression; systemic anticancer therapy; toxicity; visual acuity; visual function; visual outcome.

Figure 1

Kaplan–Meijer plot of progression-free survival for OPG treatment with BVZ. (A): Cumulative PFS overall population after start of treatment with BVZ for OPG: PFS reduces from 70.9% to 38.0% from 18 (green reference line) to 36 months (red reference line) after start (presumed 6 and 24 months after intended cessation of therapy). (B): Cumulative PFS between the NF1 (n = 13) and KIAA1549-BRAF fusion positive population (n = 9) (log rank: p < 0.01). Black line: reference line at 12 months: median completion of therapy cycles. Abbreviations: BVZ; bevacizumab, PFS: progression-free survival.