P17.28.B SURVIVAL IN MGMT-METHYLATED GBM TREATED WITH COMBINED TEMOZOLOMIDE AND LOMUSTINE IN ROUTINE CARE: AN UPDATED AND EXPANDED UK RETROSPECTIVE MULTI-CENTRE COHORT STUDY

Abstract BACKGROUND Glioblastoma (GBM) continues to have a poor prognosis. In 2019, the NOA-09 trial suggested that in patients with MGMT methylated GBM, chemo-radiotherapy with combined Temozolomide and Lomustine (TELOM) was superior to chemo-radiotherapy with temozolomide alone. However, there was a significant selection effect and outcomes in routine care are rarely reported, with only one published case series. The NRG BN-011 trial is exploring the same question in the USA, but has not published any results. Here we report data from the use of the NOA-09 protocol in routine care in 3 centres in the UK. MATERIAL AND METHODS We collected retrospective data on outcomes in patients with MGMT methylated GBM treated at three institutions with TELOM. To be eligible, patients had to have a histological diagnosis of newly diagnosed GBM or IDH-mutant Grade 4 astrocytoma, and have received chemo-radiotherapy (40Gy/15# or greater) with TELOM in either the adjuvant or concurrent and adjuvant setting. We extracted data on demographics, histological subtype, survival and other treatments. Patients treated between Jan 2020 and Jan 2025 were included, with follow-up until 28th April 2025. RESULTS We identified 40 patients from 3 centres (34, 5, 1 pts respectively). Median age was 56, and 68% were male. 3 were IDH-mut, 33 received 59.4-60Gy of radiotherapy, while the others received 40-45Gy/15#. Median follow up from diagnosis was 28 months. At time of analysis, 15 patients had died, with a median survival of 33.9 months. CONCLUSION Combined TELOM is feasible to deliver in the UK, with reasonable survival and toxicity rates. For practical reasons, many patients received concurrent RT & TMZ, and had adjuvant TELOM. Survival is significantly better than patients with MGMT-methylated GBM in the Stupp trial (median OS of 23.4 months), despite some being older or less fit, and thus receiving hypofractionated RT. We continue to update data, would encourage others to contribute and are working to develop a prospective multi-centre trial.