Abstract Purpose: The purpose of the study was to determine if the Preparedness Assessment for the Transition Home (PATH©), a validated caregiver assessment instrument, would be helpful in identifying gaps in preparation of primary caregivers of patients with glioblastoma multiforme (GBM). The PATH© was designed to assess caregiver readiness to assist the healthcare team in developing tailored solutions to meet the needs of caregiver/patient dyads. Methods: Former primary caregivers (spouses or life-partners) of now deceased patients with GBM who were members of the private Facebook (FB) group “Widows and Widowers of GBM” reviewed the instrument and completed a web-based survey via Qualtrics. Following IRB approval (#H22-0103) and approval from the FB group administrator, a survey link was posted on the FB group page and left open for 3 weeks in Spring 2023. Participants were asked to review the 25 PATH© items and respond to 4 yes/no or Likert scale questions about whether the instrument would have helped to better prepare them for the caregiving role across the phases of GBM disease trajectory (acute, living with disease progression, end-of-life). A free text option was included so caregivers could provide suggestions for tool revision to better address the needs of caregivers of patients with GBM. Summary statistics were calculated for interval and ratio variables. ANOVA and t-test were conducted to determine whether there were differences across stages among the variables (stage of disease trajectory and helpfulness score). Chi-square and Fisher’s exact test were conducted to examine whether helpfulness and overall helpfulness were independent. A linear regression was conducted to assess whether the different phases of the disease trajectory predicted tool helpfulness. The GBM Caregiver Study team met to review, analyze, code free text feedback, and identify and define code themes. Results: Demographics were completed by 191 study participants; 124 reviewed the PATH© instrument and completed the survey. Ninety-two percent of participants reported that the PATH© instrument would be helpful across all stages of the disease trajectory, with the majority selecting “Very” or “Somewhat” helpful. Only 8% of participants did not think the instrument would be helpful at end-of-life, and 6% of participants did not think the instrument would be helpful at other stages of the disease trajectory. Fifty-four participants suggested changes to the existing instrument for GBM caregivers. From these open-ended responses, four themes were identified: education, access to care team and resources, care at the end-of-life/after death, and self-care. Conclusion: Study results indicated using the PATH© instrument in the GBM population would be helpful to assess caregiver preparation. Study collaborators are actively planning future research, building on the findings of this study, to explore the impact of how implementing a systematic caregiver assessment and tailored care plans and/or interventions can improve caregiver readiness and reduce caregiver burden. Citation Format: Elizabeth James, Marlee Wallace, Megan Chard, Barbara Lutz, Laurie Minns. Former caregivers of patients with glioblastoma multiforme report the Preparedness Assessment for the Transition Home (PATH©) instrument is helpful throughout the disease trajectory [abstract]. In: Proceedings of the AACR Special Conference on Brain Cancer; 2023 Oct 19-22; Minneapolis, Minnesota. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_1):Abstract nr B040.