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Andrzej Tysarowski
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P37 - Pathology - Biomarker Testing (ID 107)
- Event: WCLC 2020
- Type: Posters
- Track: Pathology, Molecular Pathology and Diagnostic Biomarkers
- Presentations: 2
- Moderators:
- Coordinates: 1/28/2021, 00:00 - 00:00, ePoster Hall
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P37.02 - Identification of Gene Fusions and Mutations in Patients with NSCLC using two Diagnostic Approaches: Rapid qPCR and NGS (ID 3731)
00:00 - 00:00 | Presenting Author(s): Andrzej Tysarowski
- Abstract
Introduction
Background
The mutation detection, and especially fusion gene identification in patients with non-small cell lung cancers (NSCLCs), is currently a key step in the diagnosis and treatment decision. Therefore, methods are constantly being developed to be more specific, rapid and provide extensive biomarker analysis. NGS seems to be the most suitable diagnostic approach. However, this method is time-consuming, costly, and requires highly specialized devices and analytical background. Consequently, novel rapid and sensitive tests basing on qPCR emerge.
Aim
The aim of this study was to compare the diagnostic yield of NGS (RNA based sequencing) and qPCR- based Lung Cancer PCR Panel, which identifies 231 variants (gene fusions and point mutations) in 11 genes (ROS, ALK, NTRK1/2/3, RET, MET, KRAS, HER2, BRAF, EGFR) in patients treated in a single cancer center.
Methods
194 solid tumors formalin-fixed paraffin-embedded (FFPE) specimens from NSCLC patients were selected for the study. The samples were primarily analyzed using NGS (Archer, RNA-based anchored multiplex-PCR) where gene fusions or point mutations (single nucleotide substitutions and small insertions/deletions) were detected or negative results were obtained. In a second step samples were analyzed again by using a qPCR panel (AmoyDx, Lung Cancer PCR Panel).
Results
194 samples (66 with gene fusions, 72 with point mutations and 56 negative samples) were analyzed with both methods. The qPCR enabled detection of 45/66 gene fusions (68%). In 21/66 cases fusions were not detected (32%), of which 12 were beyond the scope of the qPCR test. In 9 cases the fusions were not detected due to unknown reason. The qPCR test enabled detection of 74 point mutations. 72 of them were also detected using NGS, while 2 were found in cases previously classified as negative by NGS testing. Finally, 54cases were negative in both tests.
Conclusion
This comparative study showed high concordance (89%) between qPCR and NGS panels. The multigene PCR panels seem to be good alternative to NGS panels and can be seriously considered as screening methods due to their universality, methodological simplicity, cost, and short time of analysis
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P37.09 - Comparison of 3 Different Methods for Determination of EGFR p.Thr790Met mutation in patients with NSCLC (ID 3761)
00:00 - 00:00 | Presenting Author(s): Andrzej Tysarowski
- Abstract
Introduction
Due to the frequent lack of tissue, liquid biopsy testing is a widely accepted method in the diagnosis and monitoring of patients with NSCLC. This is also more convenient for patients than (re-) biopsy of tumor tissue. In 2016 we started analysis of p.Thr790Met resistance mutation in circulating tumor DNA (ctDNA) of NSCLC patients using classical quantitative Polymerase Chain Reaction (qPCR). However, among 22 cases, we only detected 5 positive, which gave us relatively low detection rate of 23%. Hence, we introduced high sensitivity qPCR, which enabled detection of 19 p.Thr790Met -positive cases among 31 tested (61%).
Considering those large outcome differences and the fact that molecular methods become more sensitive, the aim of the study was to compare the diagnostic yield of 3 different methods that are commonly used.
Methods
Patients with NSCLC were primarily treated with an EGFR tyrosine kinase inhibitor (TKI). When progressing, blood was taken to determine p.Thr790Met mutation as a marker of resistance and decision point for further treatment. CtDNA determination was performed using three different approaches: Classic qPCR (AmoyDx, EGFR29 test), highly sensitive qPCR (AmoyDx, SuperARMS EGFR) and digital droplet PCR (ddPCR). 41 samples from patients after diagnosis of progression by radiological imaging were analyzed using classic qPCR and highly sensitive qPCR and 90 samples from patients before and after diagnosis of progression by radiological imaging using highly sensitive qPCR and ddPCR.
Results
The classic qPCR found 14/41 mutations (34%), while highly sensitive qPCR detected mutations in 30/41 samples (73%). Further analysis revealed that among 90 samples, both highly sensitive qPCR and ddPCR were concordant in 85 cases, including 23 positive and 52 negative cases (94% concordance rate). In 13 cases ddPCR detected mutation in the sample that was negative in highly sensitive qPCR, and 2 cases were only detected by highly sensitive qPCR and remained negative in ddPCR.
Conclusion
Classical qPCR tests (sensitivity level 1%-5%) can be used for the identification of activating mutations in the EGFR gene in tissue, but are not suitable for the detection of p.Thr790Met resistance mutation in plasma even in patients with progression demonstrated by radiological imaging.
Although the gold standard for detection of mutations in ctDNA is ddPCR, high-sensitivity qPCR tests (sensitivity level <1%) seem to be equally effective.
The practical experience in p.Thr790Met mutation detection may be regarded as a model procedure for detection of other resistance mutations e.g. p. Cys797Ser in EGFR or mutations in the ALK, ROS1, or NTRK genes.
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P78 - Immunotherapy (Phase II/III Trials) - Immune Checkpoint Inhibitor Single Agent (ID 255)
- Event: WCLC 2020
- Type: Posters
- Track: Immunotherapy (Phase II/III Trials)
- Presentations: 1
- Moderators:
- Coordinates: 1/28/2021, 00:00 - 00:00, ePoster Hall
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P78.10 - Immunotherapy in Non-Small Cell Lung Cancer with High PD-L1 Expression and Coexistent RET- Fusion: The Description of Two Cases. (ID 3718)
00:00 - 00:00 | Author(s): Andrzej Tysarowski
- Abstract
Introduction
Pembrolizumab is widely used as first-line treatment in patients with advanced non-small-cell lung cancer (NSCLC) and high expression of PD-L1. The activity of pembrolizumab in NSCLC patients (pts) with rare molecular alterations is poorly characterized. RET rearrangements are identified in 1-2% of NSCLC pts. Two cases of RET-rearranged NSCLC pts with PD-L1>50% treated with pembrolizumab are described.
Methods
Patients were qualified for treatment within routine practice. PD-L1 expression was assessed by immunohistochemistry. RET-fusions was detected in Next Generation Sequencing using FusionPlex Comprehensive Thyroid and Lung (CTL) Kit and sequenced on MiniSeq (Illumina). Efficacy of treatment was assessed according RECIST 1.1
Results
69-year old man, never-smoker, without comorbidities, minimalny symptomatic was diagnosed as stage IV NSCLC adenocarcinoma -PD-L1 90%, RET-fusion KIF5B [15]-RET[12] was found. Pembrolizumab (200mg i.v. every 21 days) was initiated. Two months later pathological fracture of Th10 was diagnosed. CT scan revealed progressive disease (PD)within the liver and both lungs. Despite palliative chest radiotherapy rapid clinical deterioration occurred. The patient died 3 months after the diagnosis.
65-year old woman, never-smoker, without comorbidities was diagnosed as stage IV NSCLC adenocarcinoma - PD-L1 70%, RET-fusion CCDC6 [1]-RET[12] was found. Pembrolizumab was administered, but 3 months later PD was found (mediastinal lymph nodes progression, new lung nodules, bone lesions and liver metastases). Palliative chest radiotherapy was delivered. No active treatment was offered and best supportive care was initiated afterwards.
Conclusion
Despite the high PD-L expression (observed seldom in patients with RET abnormalities) no benefit of immunotherapy was observed in our patients. The optimal treatment for patients with RET fusion is nowadays a targeted therapy. Unfortunately, it was unavailable when both patients were qualified for the treatment.
