Novel multiplex droplet digital PCR assay for scoring PD-L1 in non-small cell lung cancer biopsy specimens.
Lung Cancer
; 134: 233-237, 2019 08.
Article
in En
| MEDLINE
| ID: mdl-31319986
ABSTRACT
OBJECTIVES:
Immune checkpoint inhibitors have become integrated into the clinical management of non-small cell lung cancer (NSCLC). Using RTqPCR, we have previously identified a gene expression panel that detected presence of malignant cells (MMP9TIMP3 ratio) and quantified PD-L1 transcript levels in small biopsy specimens. However, RTqPCR has diagnostic limitations as it does not generate absolute copy number and is not readily multiplexed. To address this, we have developed a multiplex droplet digital PCR (ddPCR) assay. MATERIALS ANDMETHODS:
Biopsies obtained from NSCLC patients (nâ¯=â¯48 adenocarcinoma and nâ¯=â¯40 squamous cell carcinoma) and control lung biopsy specimens (nâ¯=â¯20) were analysed. Absolute MMP9, TIMP3 and PD-L1 transcript copy numbers were determined within a single assay by multiplex ddPCR using Taqman primers and the QX200 Droplet Digital PCR System. RESULTS ANDCONCLUSIONS:
Using our optimised triplex ddPCR assay, the MMP9TIMP3 ratio was significantly elevated in NSCLC biopsies and using a cut-off of >0.028, was 99% (95% CI; 80.5-94.5) sensitive and 80% specific for identifying malignant biopsies. The PD-L1TIMP3 ratio significantly associated with PD-L1 tumour cell immunohistochemistry staining (râ¯=â¯0.539, pâ¯<â¯0.0001) and was significantly higher in biopsies with >50% PD-L1 tumour cell staining (pâ¯<â¯0.0001). In summary, a major advantage of our workflow is that it can accurately quantify PD-L1 tumour levels and provide sufficient nucleic acid for screening additional targetable mutations such as EGFR, ALK and ROS1 from a single small biopsy, thereby potentially avoiding the need for re-biopsy. Future studies will need to determine diagnostic ddPCR values that are predictive of clinical response to PD-1/PD-L1 immunotherapy.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Biomarkers, Tumor
/
Carcinoma, Non-Small-Cell Lung
/
B7-H1 Antigen
/
Multiplex Polymerase Chain Reaction
/
Lung Neoplasms
Type of study:
Prognostic_studies
Limits:
Female
/
Humans
/
Male
Language:
En
Journal:
Lung Cancer
Journal subject:
NEOPLASIAS
Year:
2019
Type:
Article
Affiliation country:
Australia