LGG-40. Growth hormone replacement in children on therapy with Vemurafenib for Low Grade Glioma

BRAF inhibitors (iBRAF) are a therapeutical option for pediatric Low-Grade-Gliomas (pLGG), but their chronic use may be needed to prevent tumor regrowth. Growth hormone (GH) replacement in children with GH deficiency (GHD) and on oncological treatment is under debate. We report on our experience of recombinant human GH (rhGH) replacement in two children (1 Female, 1 Male) which started Vemurafenib therapy, at 5 (F) and 9,25 (M) years of age, for recurrent/progressive chiasmatic-hypothalamic pLGG, with partial response (RANO criteria) and subsequent stable disease. A diagnosis of GHD was established at 9,2 (F) and 11,2 (M) years of age (GH peaks to stimulation tests <3mcg/L), 4,2 (F) and 1,9 (M) years after Vemurafenib start. Both patients were treated with GnRH analogues for precocious puberty. rhGH dose was titrated to 0.020 mg/kg/day during follow-up based on IGF-1 levels < +2 SDS. Height remained stable in both (F: -3,4SDS; M: 0SDS), with a mean growth velocity after 2 years around 6 cm/yr. BMI increased in the F (1,59 to 1,78 SDS) and decreased in the M (2,66 to 2,56 SDS); Dual-X-ray absorbiometry confirmed high fat mass at T0 (F:54,6%; M:48%) and at T24 (F:49,2%; M:48,1%). Lipid profile improved in both patients (F: Triglycerides 175 to 152 mg/dl, LDL 195 to 155 mg/dl; M: Triglycerides 138 to 118 mg/dl, LDL 147 to 147 mg/dl, at T0 and T24, respectively), while baseline blood glucose increased (F: 83 to 96 mg/dl; M 82 to 91 mg/dl). Residual tumor was stable in both patients. CONCLUSIONS: In 2 GHD patients due to pLGG and treated with Vemurafenib, two-years of low-dose rhGH showed beneficial effects on height stabilization and on lipid profile, and a different impact on body composition parameters; rhGH was safe and not associated with residual tumor growth.