By Simon S. Lo, MB, ChB, FASTRO, University of Washington
Presenting author - Dirk Rades, MD, FASTRO, University of Luebeck
Dirk Rades, MD, FASTRO, et al. reported the results of a multicenter phase 2 trial (RAMSES-01) on the use of dose escalated precision-radiotherapy (RT) delivering either 2.633 Gy X 15 (EQD2 of 41.6 Gy assuming α/β = 10 Gy) or 2.333 Gy X 18 (EQD2 of 43.2 Gy) to favorable prognosis patients with metastatic spinal cord compression (MSCC) (N = 50 out of the 62 planned). The results were compared to a historical control group of favorable prognosis patients receiving 3 Gy X 10 (EQD2 of 32.5 Gy) (N = 266). The primary endpoint was local progression-free survival (LPFS), which was defined as no deterioration of motor function during RT and no in-field recurrence of MSCC at 12 months. According to the lead investigator, the study protocol mandated that an in-field recurrence of MSCC had to be associated with motor deficits. The secondary endpoints were improvement of motor and sensory functions, post-RT ambulatory status, relief of pain and distress, toxicity and overall survival (OS). The corresponding hotspots allowed to the spinal cord were 101.5% and 101.2%, respectively.
The trial was terminated after 50 patients were enrolled due to the worse than expected OS that resulted in the development of a new survival score, which this trial was not based on. Among the 50 patients enrolled, the 12-month LPFS and OS were 97.6% and 69.9%, respectively. Improvement of motor function was observed in 56% of the patients and 94% of the total group were ambulatory after RT. Within three months after RT, improvement of pre-RT sensory deficits and pain were observed in 57.2% (12 of 21) and 84.4% (38 of 45) of the patients, respectively. Relief of distress was reported in 78% of the patients. Grade 2 (esophagitis/dysphagia) and 3 (diarrhea/esophagitis) toxicities were observed in 20% and 4% of the patients, respectively. When compared to the historical control group, the RAMSES-01 cohort showed significantly better LPFS (p = 0.046) and a trend toward improvement of motor function (p = 0.057) after propensity score adjustment although post-RT ambulatory (p = 0.56) and OS rates (p = 0.62) were not significantly different.
The authors concluded that dose escalated precision RT was sufficiently well tolerated and yielded significantly better long term PFS compared to 3 Gy X 10 for favorable prognosis patients with MSCC and therefore appeared to be more preferable for this patient group.
Regarding the study, Dr. Rades remarked, "I am very happy that the collaboration between the participating centers from Europe and Northern America has worked so well during this project. Moreover, I am satisfied that we have reached the primary goal of the study, although we had to close it after 80% of the planned sample size/number of patients. I hope that our study will make a contribution to personalization and improvement of the treatment for patients with MSCC."
Abstract 244 - Radiotherapy for Metastatic Spinal Cord Compression with Increased Doses: Final Results of the RAMSES-01 Trial was presented on October 3, 2023, during the SS 25: CNS 1: CNS Metastases & Avoidance of Toxicity session at the 2023 ASTRO Annual Meeting.
