Timing of somatic next-generation sequencing (NGS) in metastatic prostate cancer.

150 Background: Current guidelines recommend NGS testing for all patients with metastatic prostate cancer, and yet this remains underutilized. In addition, there is uncertainty on when patients should undergo NGS testing. This study aims to determine the timing and characteristics of patients undergoing NGS testing at a single academic institution. Methods: Patients with metastatic prostate cancer diagnosed between January 2020 and January 2024 who underwent NGS testing were identified. We recorded patient and disease characteristics at time of diagnosis and time of metastatic disease. We used a time-varying cox hazard model to investigate the associations of disease factors (M stage, Gleason grade, castration resistant prostate cancer), social characteristics (race, smoking history, area deprivation index (ADI)) of the participants and the timing of NGS testing. Additionally, we analyzed median overall survival from date of metastatic disease comparing those with early (pre castration resistant prostate cancer (CRPC)) NGS testing versus late NGS (after CRPC) testing. Results: 205 patients were included. Median age at testing was 70 years [range 50-94]. 68% of participants identified as White, 26% as Black and 84% were non-Hispanic (15% unknown). At diagnosis, 56% had metastatic disease, 57% had Gleason grade group 5, 35% had T3/4 disease. 74% had ECOG 0-1 at time of metastasis. The most common source of tissue for testing was the prostate (67%) followed by blood (13%). 44% of patients developed CRPC by the last follow up date. Median time from metastatic disease to NGS testing was 2.92 months in Black patients, 2.25 in White and 1.54 in those of other races. Of the deceased (n = 66), 6.06% had testing within 3 months of death and 24.24% within 6 months of death. In multivariable time-varying analyses, higher Gleason group (HR range: 5.41-7.27, p < 0.03) and metastasis at diagnosis (12.42 [6.22, 24.78], p < 0.001) were significantly associated with increased hazard of NGS testing and thus implies a higher likelihood of earlier testing. Age at diagnosis (1.05 [1.02,1.08], p < 0.001) was also significant with each additional year increasing the hazard of NGS testing by 5%. For overall survival, the median time for early testing patients was 58.7 months versus 27.2 months for late testing patients ( p < 0.001). The relationship between NGS testing and ADI is undergoing analysis and will be shared at the meeting. Conclusions: Older age, Gleason grade group, and metastasis at diagnosis were associated with earlier NGS testing among men with metastatic prostate cancer. Nearly a quarter of men who died had testing within the last 6 months of life. As targeted therapies move earlier into treatment of metastatic prostate cancer, facilitating additional tissue acquisition and understanding of use and limitations of liquid biopsies are needed to facilitate earlier NGS testing in metastatic prostate cancer.