P27.05.B DECODING GLIOBLASTOMA SURVIVAL: UNRAVELING THE PROGNOSTIC POTENTIAL OF OLFACTORY FUNCTION IN A PROSPECTIVE OBSERVATIONAL STUDY

Abstract BACKGROUND Olfactory impairment is a common neurologic deficit among glioblastoma patients. We have previously shown that glioblastoma patients with reduced smell sensitivity had lower overall survival rates compared to those with normal olfactory function. A notable limitation in that study was the unequal distribution of prognostic factors between the two groups, and the absence of continuous olfactory assessments during treatment to investigate if therapy-associated neurotoxicity could be a contributing factor to diminished olfactory acuity. In this trial olfactory function will be evaluated in glioblastoma patients as a prognostic marker with regard to overall survival, neurocognition and quality of life. METHODS This prospective, multicenter study is set to recruit 64 glioblastoma patients alongside 64 healthy controls. Stratification of participants is based on prognostically relevant variables such as resection status, MGMT promoter methylation status, radiographic involvement of olfactory brain areas, olfactory function, age, and Karnofsky performance status scale. We utilize Sniffin´ Sticks to evaluate olfactory function through identification and threshold tests, and this assessment is carried out longitudinally throughout the therapy starting from tumor diagnosis. Infiltration of the olfactory nerves or olfactory brain are scrutinized using a high-resolution coronal T2-weighted sequence which is added to a dedicated brain tumor protocol. MRI images are independently reviewed by two board-certified radiologists from distinct institutions, who are blinded to the patients’ olfactory function status. Furthermore, quality of life data, neuropsychological testing, and psychosomatic screening are performed at specific intervals throughout the study. Also, we examine next-generation sequencing results to investigate potential genetic associations with hyposmia in glioblastoma patients. RESULTS The first participant was enrolled in May 2023. Currently, 16 patients and three controls are already enrolled (April 2024). Plans are underway to open a second study site in 2024, with the aim to complete recruitment by December 2025. Follow-up assessments will continue until December 2027. We anticipate that the final results of the study will be available in 2028. CONCLUSIONS In the process, this study is the first prospective study which investigates the olfactory function systematically as prognostic factor in glioblastoma patients.