Mutation in the gene that encodes Kirsten rat sarcoma viral oncogene homolog (KRAS ) is the most common oncogenic driver in advanced nonesmall cell lung cancer, occurring in approximately 30% of lung adenocarcinomas. Over 80% of oncogenic KRAS mutations occur at codon 12, where the glycine residue is substituted by different amino acids, leading to genomic heterogeneity of KRas-mutant tumors. The KRAS glycine-to-cysteine mutation (G12C) composes approximately 44% of KRAS mutations in nonesmall cell lung cancer, with mutant KRas G12C present in approximately 13% of all patients with lung adenocarcinoma. Mutant KRas has been an oncogenic target for decades, but no viable therapeutic agents were developed until recently. However, advances in KRas molecular modeling have led to the development and clinical testing of agents that directly inhibit mutant KRas G12C . These agents include sotorasib (AMG-510), adagrasib (MRTX-849), and JNJ-74699157. In addition to testing for known actionable oncogenic driver alterations in EGFR, ALK, ROS1, BRAF, MET exon 14 skipping, RET, and NTRK and for the expression of programmed cell-death protein ligand 1, pathologists, medical oncologists, and community practitioners will need to incorporate routine testing for emerging biomarkers such as MET amplification, ERBB2 (alias HER2), and KRAS mutations, particularly KRAS G12C, considering the promising development of direct inhibitors of KRas G12C protein.

Plasma cell-free DNA (cfDNA) genotyping is an alternative to tissue genotyping particularly when tissue specimens are insufficient or unavailable and provides critical information that can be used to guide treatment decisions in managing patients with non-small cell lung cancer (NSCLC). In this article, we review the evolution of plasma cfDNA genotyping from an emerging concept, through development of analytical methods, to its clinical applications as a standard-of-care tool in NSCLC.The number of driver or resistance mutations recommended for testing in NSCLC continues to increase. Due to the expanding list of therapeutically relevant variants, comprehensive testing to investigate larger regions of multiple genes in a single run is often preferable and saves on time and cost, compared with performing serial single-gene assays. Recent advances in nucleic acid next-generation sequencing have led to a rapid expansion in cfDNA genotyping technologies. Analytic assays that have received regulatory approval are now routinely used as diagnostic companions in the setting of metastatic NSCLC. As the demand for plasma-based technologies increases, more regulatory approvals for cfDNA genotyping assays are expected in the future.Plasma cfDNA genotyping is currently aiding oncologists in the delivery of personalized care by facilitating matching of patients with targeted therapy and monitoring emergence of resistance to therapy in NSCLC. Further advances currently underway to increase assay sensitivity and specificity will potentially expand the use of plasma cfDNA genotyping in early cancer detection, monitoring response to therapy, detection of minimal residual disease, and measurement of tumor mutational burden in NSCLC. The Oncologist ;9999:• • Implications for Practice: Plasma cell-free DNA (cfDNA) genotyping offers an alternative to tissue genotyping particularly when tissue specimens are insufficient or unavailable. Advances in cfDNA genotyping technologies have led to analytic assays that are now routinely used to aid oncologists in the delivery of personalized care by facilitating matching of patients with targeted therapy and monitoring emergence of resistance to therapy. Further advances underway to increase assay sensitivity and specificity will potentially expand the use of plasma cfDNA genotyping in early cancer detection, monitoring response to therapy, detection of minimal residual disease, and evaluation of tumor mutational burden in NSCLC. OVERVIEW OF MOLECULAR TESTING IN NON-SMALL CELL LUNG CANCER (NSCLC)The diagnostic journey for lung cancer begins with identification of the carcinoma through pathological evaluation to classify the histologic subtype, imaging (including computed tomography [CT] and magnetic resonance imaging [MRI]) to determine the extent of disease, and molecular diagnostic testing to inform therapeutic strategies [1]. Targeted therapies have transformed the treatment landscape of NSCLC. Current clinical guidelines [1-3] recommend broad

e14602 Background: The number one challenge in clinical biomarker testing for non-small cell lung cancer (NSCLC) has been the sample adequacy, given that the majority of patients are diagnosed based on minimally invasive sampling of tumor tissue. The increasingly evolving integration of high-throughput next-generation sequencing (NGS) has redefined molecular diagnostic lab practice allowing for time- and cost-efficient parallel testing of multiple biomarkers with limited specimen. Two NGS companion diagnostic (CDx) tests have been approved by FDA, FoundationOne CDx (F1CDx) and Oncomine Dx Target Test (Oncomine Dx), but with different sample acceptance criteria. The minimum tumor content requirement for F1CDx is 20% while it is 10% for Oncomine Dx. The surface area requirement for F1CDx is 25mm2 while there is no required minimum surface area for Oncomine Dx. The difference in sample acceptance criteria may have a major impact on the number of advanced NSCLC patient samples that can be accepted and tested successfully, affecting biomarker-directed therapy. Methods: The analysis of 153 NSCLC patient samples tested by Oncomine Dx at Cancer Genetics, Inc. CLIA-certified and CAP-accredited lab from October 2017 to September 2018 evaluated the sample acceptance rate, biomarker results, and testing turn-around time (TAT). Results: Based on the data, a significant portion of the samples submitted for routine clinical testing consists of extremely small specimen, including FNA cytology, with 42% less than 1mm2. 83% of samples are acceptable by Oncomine Dx criteria, compared to 14% by F1CDx. Of the 82 samples that would not be acceptable by F1CDx but generated results by Oncomine Dx, 5 were positive for EGFR exon 19 deletions and L858R, 1 for BRAF V600E, 1 for a ROS1 fusion, and the remaining 35 were positive for other actionable alterations. Average TAT was 9.2 days, consistent with recommendation by IASLC/AMP/CAP guideline of within 10 days. Conclusions: The real-world routine clinical testing of NSCLC patient samples demonstrated that a higher number of specimens with limited tumor tissue could be tested with the FDA-approved NGS CDx Oncomine Dx providing rapid TATs, actionable insights, and impacting the patient treatment outcomes.

Background: MRD testing in BCP-ALL is critical for appropriate patient management, but little is known regarding sample acquisition and testing heterogeneity across clinical practice settings. These factors may impact the quality and reliability of MRD assessment. Methods: Thirty-minute online surveys were conducted in May 2021 with hematologists/oncologists (HEME/ONCs) in the United States in both academic (acad) and community (comm) settings. Respondents were licensed physicians board certified in oncology and/or hematology who treated ≥2 BCP-ALL patients/year or ≥10 patients in the past 5 years, with over 25% of time spent in the clinical setting; pediatric HEME/ONCs were excluded. Survey enrollment is ongoing, with interim results presented here; a related survey for pathologists (PATHs) is underway. Results: HEME/ONC respondents (acad n=40, comm n=57, from 29 states) had been practicing as specialists for a median of between 11-15 years (choices were ranges, eg 6-10, 11-15, min-max was 1-34 years), and typically spent over 75% of their time in the clinic; 94% of respondents had ≥5 BCP-ALL patients/year and 92% ordered MRD tests for ≥5 patients/year. Typical timepoints for MRD testing included the end of induction/suspected complete remission, the end of consolidation, and at suspected disease progression; testing after the end of consolidation was infrequent in both groups (Table). Testing for MRD at the end of consolidation was notably more frequent in the academic setting. In both settings, the HEME/ONC ordering the MRD test generally also performed the bone marrow collection procedure (acad: 78%, comm: 56%). Resources consulted on bone marrow collection best practices included UpToDate (21%), ASH and ASCO (13%), NCCN guidelines (13%), and hematology/oncology journals. About half of practices had defined institutional protocols for bone marrow collection (acad: 55%, comm: 47%), nearly all of which were developed internally. The amount of bone marrow sample collected showed high variability, ranging from 1-10 draws (median=3) and 1-30 mL sample per draw (median=5 mL). While 49% of HEME/ONCs performed <5 draws and extracted ≤6 mL per draw, 22% collected 10 mL/draw, and 10% collected 20 mL/draw; the remaining 18% reported >5 draws and/or >6 mL per draw. In both settings, the first pull was identified and labeled in 35% of procedures; in those cases, the first-pull samples were used primarily for MRD testing in 60% of cases as recommended by NCCN guidelines (vs for morphology assessment and cytogenetic studies). HEME/ONCs typically relied on the expertise of pathologists to choose MRD testing methodology.Survey results indicate that external labs (both national clinical reference labs and commercial labs) were most commonly used for MRD assessments (63%); comm HEME/ONCs were more likely to use external reference labs and acad HEME/ONCs were more likely to use in-house labs. When asked to estimate the frequency with which different MRD methods were used, mean responses were 54% flow cytometry and 40% next-generation sequencing. While all HEME/ONCs indicated that MRD results were presented clearly in lab reports, there was a desire to include more guideline information about MRD interpretation and BCP-ALL treatment. Conclusion: Interim results identified broad heterogeneity in clinical practices affecting sample collection for MRD assessment in Ph- BCP-ALL in the US, indicating several opportunities for harmonization of routine MRD assessment in BCP-ALL. These opportunities include optimization of bone marrow sample collection techniques (volume/draw and identification/use of first pull for MRD), timing/frequency of specimen collection, serial MRD surveillance after consolidation, MRD method chosen, and standardizing reports to include guideline information. There were gaps in awareness of FDA-approved methods of MRD testing for BCP-ALL. Initiatives supporting provider education and harmonization of best practices from professional guideline committees/organizations are needed to optimize outcomes of BCP-ALL patients. Figure 1 Figure 1. Disclosures Hidalgo-Lopez: Amgen Inc.: Current Employment, Current holder of stock options in a privately-held company. Roboz: Janssen: Research Funding; Daiichi Sankyo: Consultancy; MEI Pharma - IDMC Chair: Consultancy; Actinium: Consultancy; AbbVie: Consultancy; Mesoblast: Consultancy; Bayer: Consultancy; Blueprint Medicines: Consultancy; Jazz: Consultancy; Janssen: Consultancy; Astex: Consultancy; Celgene: Consultancy; Bristol Myers Squibb: Consultancy; Agios: Consultancy; Astellas: Consultancy; Jasper Therapeutics: Consultancy; Helsinn: Consultancy; Glaxo SmithKline: Consultancy; Novartis: Consultancy; Amgen: Consultancy; AstraZeneca: Consultancy; Otsuka: Consultancy; Pfizer: Consultancy; Roche/Genentech: Consultancy. Wood: Pfizer, Amgen, Seattle Genetics: Honoraria; Juno, Pfizer, Amgen, Seattle Genetics: Other: Laboratory Services Agreement. Borowitz: Amgen, Blueprint Medicines: Honoraria. Jabbour: Amgen, AbbVie, Spectrum, BMS, Takeda, Pfizer, Adaptive, Genentech: Research Funding. Velasco: Amgen Inc.: Current Employment, Current holder of stock options in a privately-held company. Elkhouly: Amgen Inc.: Current Employment, Current holder of stock options in a privately-held company. Adedokun: Amgen Inc.: Current Employment, Current holder of stock options in a privately-held company. Zaman: Amgen Inc.: Current Employment, Current holder of stock options in a privately-held company. Iskander: Amgen Inc.: Current Employment, Current holder of stock options in a privately-held company. Logan: Amgen, Pfizer, AbbVie: Consultancy; Pharmacyclics, Astellas, Jazz, Kite, Kadmon, Autolus, Amphivena: Research Funding.

278 Background: The number of targeted therapies approved for treatment of mNSCLC has increased over the past 5 years. Strategies to identify eligible patients with actionable mutations for targeted therapy include simultaneous testing of ≥ 2 genes via next generation sequencing (NGS) or multiple simultaneous gene testing (MSGT) and sequential single gene testing (SSGT). Current clinical practice guidelines strongly recommend broad molecular profiling in all patients for the simultaneous assessment of multiple genes, including EGFR, ALK and ROS1, that may have potential roles in cancer development. Limited real-world (RW) evidence is available describing the uptake of these strategies and receipt of targeted therapy. Methods: Medicare beneficiaries age 65 years or older, newly diagnosed with mNSCLC and tested for mutations of interest in mNSCLC (ALK, EGFR, ROS1, BRAF, HER2, KRAS, MET, NTRK, RET) from July 2014 - June 2018 were identified using Medicare FFS claims (100% sample) linked to biomarker results in PROGNOS NSCLC Explorer. Patients were followed from date of first metastatic diagnosis and stratified by line of therapy, testing strategy, and year of mNSCLC diagnosis. Those testing positive for an actionable biomarker were identified and then segmented by timing of receipt of a subsequent targeted therapy. Results: 12,272 beneficiaries met inclusion criteria: median age: 75 years, 51% were female, 86% white. Among mNSCLC patients with at least one biomarker test result, EGFR and ALK mutation status were the most commonly tested and reported in 85% and 63% respectively. Overall, 1540 (12.5%) tested positive for EGFR, ALK or ROS1. The relative use of NGS or MSGT vs. SSGT for biomarker testing increased over time, from 63% in 2014 to 80% in 2018. During this period, 789 patients were identified as having at least one positive biomarker test result prior to initiating 1L therapy: 635 were identified via NGS or MSGT while 154 were identified via SSGT. Despite a positive test for mutations of interest, only 292 patients received a targeted drug at 1L. Conclusions: This RW study of mNSCLC patients demonstrates an increasing trend to test patients for multiple biomarkers at once via NGS or other MSGT methods. The number of patients receiving appropriate targeted therapies was low, suggesting the need to address the barriers to administration of guideline-recommended therapy.