QPOLE Test May Be a Suitable Alternative to DNA Sequencing in Endometrial Cancer

"The laboratory-developed QPOLE test is a quick, low-cost, and accurate POLE-hotspot testing alternative for the detection of pathogenic POLE mutations, enabling implementation in clinical practice with consequences for clinical management," according to the authors of a study published in JCO Global Oncology.

The quantitative polymerase chain reaction assay QPOLE demonstrated positive accuracy, sensitivity, and specificity when screening for exonuclease domain variants within the POLE gene in patients with endometrial cancer and may be a quick and reliable option compared with DNA sequencing, according to findings from a study published in JCO Global Oncology.

In the internal validation phase of the study, the QPOLE-frequent assay, which was employed for the most common mutations, demonstrated a crude sensitivity of 93.7% (95% CI, 87.7%-99.7%) and a specificity of 100% across 158 POLE wild-type cases. Additionally, the assay produced a sensitivity of 94.6% (95% CI, 89.4%-99.7%) after confirmatory DNA sequencing for 11 cases (4.7%) within the equivocal range. Moreover, the QPOLE-rare-1, which investigators used for detecting rare POLE variants, yielded a sensitivity and specificity of 100% when used on its own and in combination with DNA sequencing.

In the external validation portion of the study, the QPOLE-frequent assay demonstrated a specificity and sensitivity of 100% across 17 POLE mutations. Across 6 rare POLE variants, the QPOLE-rare-1 and QPOLE-rare-2 assays both produced a sensitivity and specificity of 100%. Even when considering equivocal cases (10.4%) requiring additional DNA sequencing, the overall accuracy was 100% with and without DNA sequencing. Moreover, the specificity and sensitivity were both 100%.

In a combined analysis of the internal and external validation portions including 99 instances of POLE-mutated endometrial cancer, QPOLE demonstrated an overall accuracy of 98.6% (95% CI, 97.2%-99.9%), sensitivity of 95.2% (95% CI, 90.7%-99.8%), and specificity of 100%. When investigators performed DNA sequencing only for equivocal results following up-front QPOLE testing, sensitivity was 96.0% (95% CI, 92.1%-99.8%), and specificity was 100%.

“The laboratory-developed QPOLE test is a quick, low-cost, and accurate POLE-hotspot testing alternative for the detection of pathogenic POLE mutations, enabling implementation in clinical practice with consequences for clinical management,” the study authors stated.

Investigators of this study developed and validated QPOLE as a rapid, low-cost POLE hotspot test for use among patients with endometrial cancer. The study involved the use of 3 assays, including QPOLE-frequent for detecting all 5 commonly occurring mutations, QPOLE-rare-1 for detecting 5 of 6 rare variants, and QPOLE-rare-2 for detecting P436R.

Investigators collected DNA from formalin-fixed paraffin-embedded tumor tissue samples from patients assessed at Leiden University Medical Center between 1988 and 2021 and completed DNA isolation between 2017 and 2022. Of 234 patients in the internal validation group, 158 had POLE wild-type endometrial cancer, and 76 had ­POLE­-mutated disease.

An external validation cohort included patients treated at Vancouver General Hospital and Surrey Memorial Hospital. Among 48 patients in the external validation group, 25 patients had POLE wild-type disease, and 23 had POLE-mutated disease.

DNA samples with a pathogenic variant allele frequency (VAF) of at least 10% were classified as a POLE mutation. Investigators designed the QPOLE to reduce the turnaround time for POLE status assessment to 4 to 6 hours compared with a timeframe of up to 1 or more weeks when using conventional next-generation sequencing.

Overall, 63 of 76 POLE mutation cases in the internal validation cohort included a P286R or V411L-C/T mutation. The VAFs for POLE mutations ranged from 15.0% to 81.6%. In the LUMAC cohort, patients frequently had no specific molecular profile (42.6%), mismatch repair deficiency (dMMR; 19.0%), and p53-abnormal disease (11.6%). Additionally, 90.5% had endometroid disease.

Across the external validation cohort, VAFs ranged from 12.5% to 38.68% for 23 POLE mutation cases. Of patients with POLE wild-type tumors, most had no specific molecular profile (26.5%), dMMR disease (22.1%), and p53-abnormal disease (17.6%). Moreover, 85.3% of patients had endometrioid histology.

Reference

Van den Heerik ASVM, Ter Haar NT, Vermij L, et al. QPOLE: A quick, simple, and cheap alternative for POLE sequencing in endometrial cancer by multiplex genotyping quantitative polymerase chain reaction. JCO Global Oncol. 2023;9:e2200384. doi:10.1200/GO.22.00384