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Jose Pacheco
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P1.01 - Advanced NSCLC (ID 158)
- Event: WCLC 2019
- Type: Poster Viewing in the Exhibit Hall
- Track: Advanced NSCLC
- Presentations: 1
- Now Available
- Moderators:
- Coordinates: 9/08/2019, 09:45 - 18:00, Exhibit Hall
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P1.01-87 - Acquired Resistance Mechanisms and Clinical Outcomes for Patients with Epidermal Growth Factor Receptor (EGFR) Positive Non-Small Cell Lung Cancer (NSCLC) Treated with Osimertinib (Now Available) (ID 2960)
09:45 - 18:00 | Author(s): Jose Pacheco
- Abstract
Background
Osimertinib is a 3rd generation TKI approved for stage IV EGFR+ NSCLC in the first line or post-progression with T790M. The spectrum of osimertinib resistance mutations and clinical outcomes post-osimertinib progression are not well described.
Method
Single-center retrospective review of patients with stage IV EGFR+ NSCLC treated with osimertinib was conducted. Resistance mutations were determined via tissue biopsy or circulating tumor DNA (Guardant) prior to and at time of progression on osimertinib. PFS was calculated using Kaplan-Meier method. PFS1 is start of osimertinib to radiographic progression. PFS2 is start of next therapy after osimertinib to next radiographic progression.
Result
We identified 95 patients with stage IV EGFR+ lung adenocarcinoma treated with osimertinib detected via NGS (56/95), real-time PCR (29/95), Sanger sequencing (8/95), and other techniques (2/95). Most patients were female (63/95) and never smokers (72/95). Osimertinib resistance and post-progression patterns are shown in Table 1. Potentially targetable mutations were found in 55% (26/47) samples and 14% (6/47) samples had oncogenes targetable with available TKIs. TP53 mutations prior to osimertinib did not significantly influence PFS (36 weeks vs 39 weeks; p = 0.13). MET amplification was only seen in the setting of undetectable T790M or in patients who received first line osimertinib. Median PFS1 for 1st line EGFR TKI (n=17), 2nd line EGFR TKI (n=41), 3rd or greater line EGFR TKI (n=29) was 36, 45 and 39 weeks respectively (p=0.268) with median follow up of 59, 81, and 64 weeks. 10 patients received locally ablative radiotherapy for oligoprogressive disease (defined as ≤ 3 progressive sites) and continued osimertinib post-progression with median PFS2 of 49 weeks.
Conclusion
There is utility to repeat biopsy after progression on osimertinib as targetable oncogenes can be found. Presence of TP53 prior to starting osimertinib did not influence PFS1. Continuing osimertinib and adding radiotherapy for oligoprogressive disease does increase post-progression PFS.
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P1.14 - Targeted Therapy (ID 182)
- Event: WCLC 2019
- Type: Poster Viewing in the Exhibit Hall
- Track: Targeted Therapy
- Presentations: 1
- Now Available
- Moderators:
- Coordinates: 9/08/2019, 09:45 - 18:00, Exhibit Hall
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P1.14-09 - Unveiling Hidden MET-Mediated Primary Alectinib Resistance in ALK-Positive Non-Small Cell Lung Cancer (Now Available) (ID 1989)
09:45 - 18:00 | Author(s): Jose Pacheco
- Abstract
Background
Alectinib is an ALK inhibitor that is currently used for the treatment of ALK-positive NSCLC. This next generation ALK inhibitor was initially used as second-line therapy following resistance to crizotinib. More recently, alectinib has superseded crizotinib, an ALK/ROS1/MET inhibitor, as a first-line therapy due to its superiority in phase III trials. Although patients enjoy durable responses to alectinib, they eventually develop resistance. Here we describe four cases of primary resistance to alectinib in which the patients show little to no response to alectinib when administered as first or second-line therapy.
Method
In order to investigate primary resistance to alectinib, tissue was obtained during re-biopsy and subjected to routine clinical genetic analyses including gene fusion detection and genetic mutation analysis using the Archer FusionPlex and VariantPlex assays, respectively. Concurrently, at the time of biopsy, additional fresh tissue was procured for cell line derivation. The primary cell line was then used to assess ALK and other inhibitors’ potency by cell viability assays. Targeted analysis of signaling pathways was performed in the cell lines via western blot analysis and proximity ligation assays to determine resistance mechanisms.
Result
We present 4 cases of ALK patients with primary resistance to alectinib when used as either first (n=3) or second-line therapy (n=1). In 3 of the 4 cases, routine clinical resistance testing revealed no additional ALK or non-ALK related genetic abnormalities (e.g.; ALK kinase domain mutations, other oncogenic gain-of-function mutations, or gene amplification). However, examination of targeted gene expression data indicated elevated RNA transcripts of MET alone or combined MET and AXL. Analysis of the cell lines derived from these 4 patients further implicates MET in alectinib resistance alone or together with AXL or ERBB3. Signaling analysis shows that MET provides a prosurvival effect, signaling through the PI3K/AKT pathway. In the case where MET was the sole identified bypass mechanism of alectinib resistance, the patient also rapidly progressed through brigatinib, but a regimen of crizotinib plus brigatinib resulted in rapid tumor shrinkage.
Conclusion
Here, we document cases of primary resistance to alectinib therapy using human-derived cell lines to expose novel resistance mechanisms not identified by routine clinical testing. We show that MET is a critical component and serves as a bypass mechanism of alectinib resistance either alone or in combination with AXL or ERBB3. We also demonstrate that crizotinib could overcome MET-mediated ALK resistance in a patient.
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P2.03 - Biology (ID 162)
- Event: WCLC 2019
- Type: Poster Viewing in the Exhibit Hall
- Track: Biology
- Presentations: 1
- Moderators:
- Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
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P2.03-06 - Detection of ctDNA and Correlation with Tumor Mutation Testing in Early Stage NSCLC (ID 2950)
10:15 - 18:15 | Author(s): Jose Pacheco
- Abstract
Background
In advanced disease, circulating tumor (ctDNA) has proven a viable alternative to tissue based molecular testing to identify patients with lung adenocarcinoma (LUAD) eligible for targeted therapies. ctDNA is under investigation for utility in early cancer detection and non-invasive companion diagnostics to allow for identification of targetable biomarkers in patients who may benefit from neoadjuvant targeted therapy. However, in the early stage cancer setting, ctDNA has been limited by reliance on interrogation of genomic alterations alone resulting in low detection rates (13% stage I, 22% stage II, 40% stage III, Abbosh et al, Nature 2017). Herein, we test the ability of the novel ctDNA-based assay to detect ctDNA in patients with early stage LUAD, and secondarily, to identify targetable oncogenes in these patients.
Method
Eligible patients had stage IA-IIIA LUAD deemed surgically resectable. Following consent, plasma samples were collected prior to surgery or neoadjuvant therapy. Circulating free DNA (cfDNA) was analyzed for ctDNA with the LUNAR assay (Guardant Health), which utilizes an integrated genomic and epigenomic ctDNA assessment at a tumor allelic fraction down to 0.01% to report “ctDNA detected” or “ctDNA not detected”. This single blood sample cfDNA assay utilizes a variant filter to distinguish tumor from non-tumor derived cfDNA alterations in the absence of other genomic DNA (e.g. tissue sequencing or peripheral blood mononuclear cells). Molecular analysis of paired FFPE primary tumor specimens was performed using the Illumina TruSight Tumor 26 or ArcherDx VariantPlex Solid Tumor library preparation kits followed by next-generation sequencing (NGS) on the Illumina platform in a CLIA-certified laboratory. Sensitivity for tumor driver mutation detection is evaluated by comparing tumor drivers identified in ctDNA with those identified in corresponding paired primary tumor specimens.
Result
We enrolled 31 patients with early stage LUAD who ultimately underwent surgical resection, 29 of whom completed LUNAR testing (19 with stage I, 4 with stage II and 6 with stage IIIA). Analysis of tumor tissue identified a driver mutation in 83% (24/29) of cases (KRAS=11, EGFR=10, MET=3, ALK=1). A genomic cancer-associated mutation was identified in 16%, 25% and 67% in stage I, II, and III, respectively. The LUNAR assay demonstrated 100% specificity for EGFR and KRAS mutations. The incorporation of the epigenomic classifier enhanced pre-operative ctDNA detection to 26% of Stage I, 50% of stage II, and 67% of stage III patients.
Conclusion
The majority of patients with early stage LUAD had an identifiable oncogene alteration, consistent with data from advanced disease. Utilizing a plasma only, integrated genomic and epigenomic ctDNA assay demonstrated improved performance over tumor informed approaches. The ctDNA detection rate increased with disease stage, consistent with increased tumor burden. With 100% tissue concordance of EGFR and KRAS alterations identified in ctDNA, ctDNA may prove an option for not only identification of early stage LUAD, but also identifying biomarker positive LUAD eligible for clinical trials utilizing targeted therapy in the neoadjuvant setting.
