Background Several epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKI) have been approved for first‐line (1L) treatment of EGFR‐mutated metastatic non‐small cell lung cancer (mNSCLC) in the United States (US). Real‐world analyses of 1L treatment patterns with EGFR TKIs, including the third‐generation EGFR TKI osimertinib which was most recently approved in 2018, are still sparse. Methods This retrospective observational study used data from IQVIA's prescription claims (LRx) and medical claims (Dx) databases. mNSCLC patients newly treated with any EGFR TKI in the 1L setting were identified from January 1, 2015 to April 30, 2020; the first date of EGFR TKI (third‐generation osimertinib, first‐generation [erlotinib, gefitinib], or second‐generation [afatinib, dacomitinib]) was the index date. Treatment patterns were reported in the cohorts stratified by 1L EGFR TKI. Results A total of 2505 patients were included in the study (982 osimertinib, 1060 first‐generation, and 463 second‐generation EGFR TKI). Beginning in 2018, osimertinib became the most common 1L EGFR TKI (66.7%) and in early 2020, it accounted for 90.6% of 1L EGFR TKIs. Nearly all patients (>97%) were treated with 1L EGFR TKI monotherapy. Patients with 1L osimertinib had longer treatment duration compared to patients with 1L first‐ or second‐generation EGFR TKI (median months: 17.8 vs. 8.7 vs. 10.5, respectively; log‐rank test for comparisons with osimertinib p < 0.0001) over median follow‐up times of 9.8, 20.5, and 19.3 months. 32.5% and 36.3% of the first‐ and second‐generation EGFR TKI cohorts, respectively, had evidence of 2L treatment. Osimertinib monotherapy accounted for the majority of 2L treatments (58.3%/60.7%) and 11.3%/8.9% had 2L chemotherapy or immuno‐oncology therapy following 1L first‐ or second‐generation EGFR TKI. Conclusion In this real‐world study of a US claims database, 1L treatment duration was longer with osimertinib compared with other EGFR TKIs. Future studies with longer follow‐up are recommended to understand treatment patterns after progression on EGFR TKIs.

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402 Background: Tissue biopsy (TB) testing is the standard of care to guide the selection of targeted therapy in EGFRm patients with mNSCLC. However, liquid biopsy (LB) tests are increasingly important in assessing tumor genomics at mNSCLC diagnosis. This study assessed real-world utilization of LB for EGFR testing in 1L setting and its influence on 1L treatment decisions in mNSCLC patients. Methods: Adults newly diagnosed with mNSCLC from January 1, 2019 to May 31, 2021 and treated with 1L were identified from the Flatiron EMR database. LB utilization and patterns (either used alone or in combination with TB) were evaluated. “Concurrent” (TB & LB) testing was defined as patients with both test order dates prior to result dates for either test, while “sequential” (TB & LB) testing was defined as patients having one test’s result date before the other test’s order date. As patients could have multiple biomarker tests, the first two EGFR tests following diagnosis were evaluated. Results: Of 5,036 patients that met the study criteria, 89.2% (N = 4,494) had EGFR testing following diagnosis. Among those tested for EGFRm, 63.7% (N = 2,864) had TB only, while 36.3% (N = 1,630) had LB (LB only: 37.9%; concurrent: 36.1%; sequential: 26.0%). Around 90% of patients with LB had NGS testing (87.7% received LB testing within 90 days of diagnosis). Among patients who initiated 1L after EGFR testing, the median (IQR) time in days from testing to 1L initiation varied by testing patterns: LB only: 18 (12-30); concurrent: 29 (22-39); sequential: 28 (18-41). Disagreement in test results was 10.6% for patients who had conclusive test results for both TB and LB tests. Among concurrent EGFRm patients (N = 130), 21.5% initiated 1L after receiving LB results (and before TB results) and 60.0% after receiving both test results. Among patients with sequential LB followed by TB (N = 10), 80.0% of them initiated 1L after receiving LB results and before TB results (Table). Conclusions: In this real-world study among mNSCLC patients in a 1L setting, more than one-third used LB for EGFR testing, either alone or in combination with TB. Among LB patients, majority had NGS testing.[Table: see text]

401 Background: This study compares patient characteristics, clinical conditions, the prevalence and timing of lung cancer symptoms, and diagnostic procedures from onset to mNCSLC diagnosis for patients with and without targetable mutations. Methods: This was a retrospective claims analysis of Medicare Advantage and commercially insured adult mNSCLC patients (11/01/2012 - 01/31/2020) with continuous health plan enrollment (24 months pre-index and ≥2 months post-index) around the index date (mNSCLC diagnosis). Patients on targeted therapy post-diagnosis were assigned to the targeted group (TG); non-targeted group (NTG) otherwise. Twenty pre-specified lung cancer related symptoms, baseline comorbidities, and diagnostic procedures were examined in the pre-index period. Results: The study comprised 2,940 patients (TG: 390; NTG: 2,550); TG had lower mean age (65.8yrs vs 69.2yrs; p < 0.001), more females (59.5% vs 50.6%; p = 0.001), and lower tobacco use (55.9% vs 92.5%; p < 0.001). Mean TG Charlson score was 1.37 in the TG vs 1.93 in the NTG; p < 0.001. There were no significant differences in prevalence of any lung cancer related symptoms (TG 81.8% vs NTG 83.5%; p = 0.4). When comparing the 20 individual, pre-specified lung cancer related symptoms (cough, dyspnea, hemoptysis, etc.), there were also no significant differences between the study cohorts. For patients with symptoms, the mean times from the first symptom to mNSCLC diagnosis were similar (TG: 339.3 days; NTG: 363.1 days; p = 0.13)(Table). There were significant differences in the proportion of patients with comorbidities between study cohorts (TG 64.4% vs NTG 73.5%; p < 0.001). Among patients within TG, there was higher prevalence of pleural effusion (22.1% vs 12.6%; p < 0.001) and lower prevalence of COPD (17.7% vs 50.8%; p < 0.001). For diagnostic procedures, patients in TG had fewer imaging procedures than NTG (Chest x-ray 67.7% vs. 74.1%; p = 0.008, CT scan 57.2% vs 63.5%; p = 0.016, PET scan 19.0% vs 27.1%; p < 0.001); and a longer mean time from first symptom to first imaging procedure (TG: 220 days; NTG: 184 days; p = 0.015)(Table). Conclusions: Patients with and without targetable mutations may differ by some patient characteristics, but they may not differ by presentation and type of lung cancer related symptoms leading up to diagnosis.[Table: see text]

114 Background: As the treatment landscape for early-stage NSCLC continues to evolve with the recent approvals of targeted and immunotherapy agents in the adjuvant setting, it is important to understand physician referral patterns and predictors of adjuvant therapy (AT). This study examined physician referral patterns at key treatment phases and assessed predictors of receiving AT in stages IB-IIIA NSCLC patients. Methods: A retrospective study using the linked SEER-Medicare database (01/01/2010-12/31/2017) included patients newly diagnosed with stages IB-IIIA NSCLC who received surgical resection. Specialties were identified by linking NSCLC claims to AMA Physician Masterfile. AT was defined as the use of systemic chemotherapy or radiation therapy within 4 months of surgery. Multivariable logistic regression was conducted to assess predictors of receiving AT. Results: A total of 7,108 patients met study criteria (53% IB; 9% IIA; 19% IIB; 20% IIIA). Primary care physician (PCP) (71%), surgical oncologist (29%), medical oncologist (36%) were the most frequently visited first specialist during pre-diagnosis, diagnosis to surgery, and post-surgery phases, respectively. The median time from diagnosis to surgery was 44 days. After surgery, 74% patients visited medical oncologist (62% IB; 87% IIA; 83% IIB; 88% IIIA). About 41% received AT (21% IB; 64% IIA; 56% IIB; 69% IIIA). Of those, the median time from surgery to adjuvant therapy was 46 days. Later stage at diagnosis and shorter referral time to medical oncologist significantly increased the odds of receiving AT (Table). Conclusions: The strongest predictors of receiving adjuvant therapy were time to medical oncologist post-surgery and stage at diagnosis. Future studies in the era of targeted therapies can use our results as a benchmark to optimize management and outcomes as well as assess changes in referral patterns in IB-IIIA NSCLC patients.[Table: see text]