Phase II Study of a Temozolomide-Based Chemo-radiotherapy Regimen for High Risk Low-Grade Gliomas: Long-term Results of Radiation Therapy Oncology Group (RTOG) 0424.

Abstract Purpose To report the long-term outcomes of the YYY1 study of a high-risk low-grade gliomas (LGG) population treated with concurrent and adjuvant temozolomide (TMZ) and radiotherapy (RT). Patients/Methods For this single-arm phase II study, LGG patients with > 3 risk factors (age > 40, astrocytoma, bi-hemispheric tumor, size > 6 cm or preoperative neurologic function status >1) received RT (54 Gy/30 fractions) with TMZ and up to 12 cycles of post-RT TMZ. The initial primary endpoint p was overall survival (OS) at 3 years after registration. Secondary endpoints included: progression-free survival (PFS), and the association of survival outcomes with methylation status. The initial 3 year report of this study was published in 2015. Results The study accrued 136 patients, of whom 129 were analyzable. The median follow-up for surviving patients is 9.0 years. The 3-year OS is 73.5% (95% CI: 65.8-81.1%), numerically superior to the 3 year OS historical control1 OS of 54% (p Conclusions The long-term results confirmed the findings from the initial reportfor efficacy suggesting OS and PFS outcomes with the RT-TMZ regimen exceeding historical control control groups treated with radiation alone. Toxicity was acceptable.