S367
Clinical - CNS
ESTRO 2026
resistance: interim result of a phase 0/1 trial in newly diagnosed and recurrent glioblastoma. Chin Clin Oncol. 2024;13(Suppl 1):AB036. Keywords: Chemoradiotherapy, Mycophenolate Mofetil
1000 mg, or 1500 mg twice daily. Patients were randomly assigned to one of three dose levels using block randomization, each block with nine cases. MMF was started one week before and continued throughout radiotherapy with concurrent temozolomide (75 mg/m ² ). Radiation dose was 60 Gy/30# for new and 40 Gy/20# for recurrent cases. Weekly hematological and biochemical monitoring was performed; grade ≥ 3 CTCAE toxicities were recorded. Results: Twenty-three patients have completed chemoradiotherapy till date; eight patients each received 500mg and 1500mg, and remaining seven patients received 1000mg. One patient in the 1500mg cohort developed grade 4 thrombocytopenia and grade 3 neutropenia after 4 weeks of treatment, requiring treatment interruption. One patient in the 500 mg cohort developed grade 2 diarrhoea and hyponatraemia, later complicated by hospital-acquired pneumonia and sepsis leading to transient pancytopenia. The patient recovered and completed treatment. No other toxicities were observed, and the regimen has been well tolerated across all dose ranges. Grade 3 or higher toxicity was noticed only in 8.7% (2/23) of cases with no observable dose related trends. Further patient accrual is ongoing.
Digital Poster 1911
Balancing toxicity and control: lesion-based analysis of radionecrosis and dosimetry after Gamma Knife with immunotherapy and targeted therapy Zineb Belbaraka 1 , Christine Collen 1 , Paulus Kristanto 2 , Hamza Qissi 3 1 Radiotherapy-Oncology, Hôpital Universitaire de Bruxelles, Bruxelles, Belgium. 2 Biostatistics, Hôpital Universitaire de Bruxelles, Bruxelles, Belgium. 3 Medicine, Université Libre de Bruxelles, Bruxelles, Belgium
Purpose/Objective: To evaluate the incidence of symptomatic
radionecrosis (RN) and its association with lesion-level dosimetric parameters (V12Gy and GTV, in cm ³ ) in brain metastases from lung cancer or melanoma treated with Gamma Knife (GK) radiosurgery during immunotherapy or tyrosine kinase inhibitors (TKI) , aiming to explore dose–adaptation strategies. Material/Methods: This retrospective study included 205 lesionstreated with GK between 2015 and 2024, corresponding to 90 patients(lung cancer n=70, 77.8%; melanoma n=20, 22.2%). Lesions were treated with a single-fraction dose ranging from 18 to 24 Gy. Systemic treatments consisted of immunotherapy (n=71, 78.9%) or TKI (n=19, 21.1%) administered before or after GK radiosurgery. Median time from first systemic treatment to GK was 6.6 months (IQR − 14.4 to − 2.0) before GK for pre-SRS (stereotactic radiosurgery) treatments, and 1.1 months (IQR 0.3–6.0) after GK for post-SRS treatments. The primary endpointwas symptomatic RN, defined as imaging changes compatible with radionecrosis associated with clinical symptoms. RN was assessed by MRI, methionine PET and/or histopathology when available.Secondary endpoints included lesion-level correlations with V12Gy (cm ³ ) and GTV (cm ³ ). Death was treated as a competing event. Local control (LC) was evaluated per lesion. Results: After a median follow-up of 25.8 months, symptomatic RN occurred in 10 lesions (4.9%). The estimated cumulative incidence of symptomatic RN was 2% (95% CI 1–9%) at 6 months, 4% (2–12%) at 12 months, 6%(2– 13%) at 18 months, and 9% (4–18%) at 24 months. Lesions that developed symptomatic RN showed
Conclusion: Mycophenolate mofetil upto 1500mg twice daily along with concurrent radiotherapy and temozolomide appears to be well tolerated in the Indian population. Further follow up will determine its role as a sensitiser for chemoradiation. References: 1. Yalamarty SSK, Filipczak N, Li X, Subhan MA, Parveen F, Ataide JA, Rajmalani BA, et al. Mechanisms of resistance and current treatment options for glioblastoma multiforme. Cancers (Basel). 2023;15(7):2116.2. Shireman JM, Atashi F, Lee G, Ali ES, Saathoff MR, Park CH, et al. De novo purine biosynthesis is a major driver of chemoresistance in glioblastoma. Brain. 2021;144(4):1230- 1246.3. Umemura Y, Clarke N, Al-Holou W, Elaimy A, Scott A, Leung D, et al. Targeting glioblastoma de-novo purine metabolism to overcome chemoradiation
Made with FlippingBook - Share PDF online