Contemporary biomarker testing rates in both early and advanced NSCLC: Results from the MYLUNG pragmatic study

9109 Background: The MYLUNG (Molecularly Informed Lung Cancer Treatment in a Community Cancer Network) consortium pragmatic study aims to identify and overcome barriers to timely and appropriate biomarker testing in patients (pts) with NSCLC. We previously reported retrospective real-world testing rates for 5 biomarkers from 2018-2020 in metastatic pts. We now report results from the prospective observational phase, including additional biomarkers in pts with both early and advanced NSCLC. Methods: This was a prospective, non-interventional cohort study of newly diagnosed pts with early stage (ES), locally advanced (LA), or metastatic NSCLC (mNSCLC) between 12/2020 and 9/2022 and enrolled from 12 community practices (69 sites) across The US Oncology Network. The proportion of pts with test results for 9 biomarkers at time of protocol initiation were examined: ALK, BRAF, EGFR, ROS1, PD-L1, KRAS, MET, NTRK, and RET. Timing of tests, use of single vs multigene NGS testing, clinical and socioeconomic factors, and reasons for not testing were collected in real time. Results: Of 1002 pts screened, 987 were enrolled and analyzed. There were 405 stage IB-IIIC pts [n = 284 stage IB-IIIA (ES cohort); n = 121 stage IIIB-IIIC (LA cohort)] and 582 stage IV pts (mNSCLC cohort). Descriptions for ES and LA vs mNSCLC pts respectively include median age 68 vs 69 yrs, 49% vs 52% female, 83% vs 77% white, 58% vs 79% adenocarcinoma histology, 71% vs 68% ECOG 0-1, and 33% vs 30% high school education level. Testing rates for ES vs mNSCLC cohorts are shown in the table below: prior to treatment initiation, 64% of ES and 83% of mNSCLC pts had at least one biomarker result; and 37% of mNSCLC pts had results for all 9 biomarkers. NGS testing occurred in 37% and 57% of the ES and mNSCLC cohorts respectively. Reasons for not testing included: barriers to ordering (42%, 25%), insufficient tissue (18%, 18%), clinical deterioration/crisis (5%, 12%), and other reasons (37%, 49%), respectively. Conclusions: As more genomic alterations are identified in NSCLC, we observed that many pts do not get full genotyping prior to treatment, and biomarker testing remains of utmost importance. Further analyses by distinct stages (e.g. LA), histology, social determinants, utilization of targeted therapies, and other reasons for not testing will be performed. These data will be used to evaluate future prospective interventions for MYLUNG, to help improve comprehensive biomarker testing for NSCLC. [Table: see text]