2022 Liquid biopsy Trends

Discovery of cfDNA and opening of precision oncology targeting actionable mutation 

In 1948, the term cell free DNA (cfDNA), nucleic acids which circulate in the blood was reported by Mandel and Métais for the first time.[1] Leon discovered the correlation with cancer in 1977.[2] Through radioimmunoassay, it was found that there are significantly higher levels of DNA in serum of metastatic patients compared to non-metastatic patients.[2] However, cfDNA did not receive attention from the research community as an evaluation marker for cancer treatment until the early 2000s where many publications on cfDNA and liquid biopsy started to flourish.[3]

Initially, the first commercialization of cfDNA for diagnostic purposes was attempted as prenatal testing to detect aneuploidies.[3,4] But a more commonly accepted way of using cfDNA began with targeting actionable mutation. The plasma-based molecular tests received FDA approval for EGFR testing in 2016 and were accepted as routine clinical practice in different guidelines.[5-8] As you can see in figure 1, from the day when cfDNA was first commercialized for non-invasive prenatal testing or for clinical research to investigate its correlation with cancer, the application of liquid biopsy has been officially specified and established to become an alternative tool in aiding treatment selection during routine clinical practice.[3,6,7,8]

Current status of ctDNA application and trends in 2022 

Circulating tumor DNA (ctDNA) is one of the most recognized types of cfDNA which is an alternative source of tissue to detect already known mutations and aid treatment selection. The National Comprehensive Cancer Network (NCCN) and European Society for Medical Oncology guidelines recommend minimally invasive liquid biopsy for patients who do not have sufficient tissue specimens to diagnose actionable mutations:EGFR, KRAS, ALK, ROS1, BRAF, etc.[6-8] In addition, liquid biopsy is recommended for genomic resistance such as T790M.[8-9]

Further investigation for the application of ctDNA for versatile use is ongoing. Not only just focusing on single mutation, interest over minimal residual disease (MRD) and sum of alleles are investigated.[10-11] In 2022, several clinical studies were performed to predict the recurrence or treatment outcome after first-line tyrosine kinase therapy (TKI), neoadjuvant, and adjuvant therapy. This blog aims to explore the key studies of 2022 that suggested the potential future use of ctDNA; how ctDNA clearance and its positivity affect the treatment outcome. 

Clinical utility of ctDNA clearance after first-line TKI and radiation therapy

Not only can ctDNA be used to detect actionable mutation and guide appropriate TKI treatment, but it can also be used to monitor the outcome after first-line TKI therapy. Behel et al. suggested the value of ctDNA monitoring response after first-line EGFR TKI therapy in stage IVB NSCLC patients.[12] Blood samples were collected before and between 2 to 5 months after treatment. ctDNA which showed negative after treatment showed significantly longer progression-free survival and overall survival by 6 months.[12]

The prognostic value of ctDNA monitoring was also explored in stage I–III NSCLC cancer patients getting radiation therapy. Nearly 30% of patients who were ctDNA cleared after radiation therapy remained free from disease recurrence significantly.[13] It suggested the potential of ctDNA as a predictor to decide whether the patient may benefit from intensive treatment such as adjuvant therapy.[13]

Clinical utility of ctDNA as surveillance tool for administration of immune checkpoint inhibitors as part of neoadjuvant and adjuvant therapy

The investigation of using immune checkpoint inhibitors as part of neoadjuvant or adjuvant therapy is another area where use of ctDNA is actively explored. There have been early trials investigating its role in early phase trials. But between the end of 2021 to 2022, phase 3 trials results underpinning the previous studies have been published.

The utility of ctDNA clearance in adjuvant therapy is suggested in IMpower010 clinical trial which was published in December 2021. This study compared  immune checkpoint inhibitor, atezolizumab with best supportive care.[14] After surgery ctDNA was collected before the adjuvant therapy. The ctDNA positivity predicted poor outcome with disease-free survival. The effect was more significant among patients who had detectable tumor cells over 1%.[14]

The result of CheckMate 816 clinical trial was published in May 2022, investigated the use of an immune checkpoint inhibitor, nivolumab combined with chemotherapy vs chemotherapy alone in resectable NSCLC patients with stage IB to IIIA.[15] As part of subanalysis, ctDNA clearance was included. Regardless of which types of treatment patients received, ctDNA cleared patients showed longer event-free survival (figure 2) and higher complete pathologic response compared to patients who still had detectable ctDNA.[15] Though ctDNA was only explored as part of subgroup analysis, it suggested that ctDNA clearance during neoadjuvant therapy may be used to predict whether it will bring favorable outcomes or not. 

There are more upcoming ongoing trials like MERMAID-1 and 2 as well which intend to incorporate ctDNA as exploratory endpoints to investigate the effect of durvalumab as adjuvant therapy in completely resected NSCLC patients and as a tool for surveillance, respectively. [16-17]

Conclusion

The use of ctDNA is explored in different settings and applied in different ways either targeting single mutation or as part of MRD test to optimize the efficacy of cancer treatment. However, its use is still limited. Currently NCCN guideline advises to limit its use to advanced metastatic NSCLC due to its sensitivity and only in limited circumstances when tissue biopsy is not available or inaccessible due to conditions of patients.[6] In addition, there are not many phase 3 trials yet to underpin the use of ctDNA with surgery, neoadjuvant, or adjuvant therapy.

To be a part of the mission to surpass the status quo and facilitate detection and guidance of cancer treatment for healthier communities, Genecast has developed ADPS™ smart DNA polymerase to confer high sensitivity with strong discrimination power to elevate real-time PCR techniques. For further information on the science behind ADPS™ technology, please check our previous blog ‘ADPS™ smart DNA polymerase, a cost-effective way to discriminate mismatch in cancer mutation detection.'

Reference

[1]P Mandel, et al. (1948) Nuclear Acids In Human Blood Plasma.C R Seances Soc Biol Fil. 142(3-4):241-3.

[2]LEON, et al. (1977) Free DNA in the serum of cancer patients and the effect of therapy. Cancer Res. 37: 646–650.

[3]Domínguez-Vigil IG, et al. (2017) The dawn of the liquid biopsy in the fight against cancer. Oncotarget. 8;9(2):2912-2922. doi: 10.18632/oncotarget.23131. 

[4]Lo YM, et al. (1997) Presence of fetal DNA in maternal plasma and serum. Lancet. 350(9560):485–487.

[5]FDA/CEDR resources page. Food and Drug Administration Web site. List of Cleared or Approved Companion Diagnostic Devices (In Vitro and Imaging Tools)

https://www.fda.gov/medical-devices/in-vitro-diagnostics/list-cleared-or-approved-companion-diagnostic-devices-in-vitro-and-imaging-tools

[6]National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology. Non-Small Cell Lung Cancer (Version 1.2023)

[7]J. Pascual, et al. (2022) ESMO recommendations on the use of circulating tumour DNA assays for patients with cancer: a report from the ESMO Precision Medicine Working Group. Annals of Oncology. 33(8):750-768

[8]Hendriks LE, et al. (2023)Oncogene-addicted metastatic non-small-cell lung cancer: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up†, Annals of Oncology 

[9]AstraZeneca AB. TAGRISSO (osimertinib). Summary of product characteristics. 2020. Available at https://www.ema.europa.eu/en/documents/product-information/tagrisso-epar-product-information_en.pdf

Accessed January 24, 2023.

[10]Genecast Blog, Clinical significance of ctDNA analysis as Minimal Residual Disease Test in Lung Cancer. https://www.igenecast.com/face-to-cancer/view.do?blogNo=73

[11]Provencio M, et al. (2022) Treatment Sequencing in Resectable Lung Cancer: The Good and the Bad of Adjuvant Versus Neoadjuvant Therapy. American Society of Clinical Oncology Educational Book 42:711-728

[12]Behel V, et al. (2022) Clinical Utility of Liquid Biopsy (Cell-free DNA) Based EGFR Mutation Detection Post treatment Initiation as a Disease Monitoring Tool in Patients With Advanced EGFR-mutant NSCLC. Clin Lung Cancer. 23(5):410-418. 

[13]Emily S. Lebow, et al. (2022) Minimal residual disease (MRD) detection by ctDNA in relation to radiographic disease progression in patients with stage I-III non–small cell lung cancer (NSCLC) treated with definitive radiation therapy. Journal of Clinical Oncology 40:16_suppl, 8540-8540.

[14]Zhou, C. et al. (2021) 2O IMpower010: Biomarkers of disease-free survival (DFS) in a phase III study of atezolizumab (atezo) vs best supportive care (BSC) after adjuvant chemotherapy in stage IB-IIIA NSCLC
Annals of Oncology, Volume 32, S1374.

[15]PM Forde, et al. (2022) Neoadjuvant Nivolumab plus Chemotherapy in Resectable Lung Cancer. N Engl J Med. 386:1973-85. 

[16]Phase III Study to Determine the Efficacy of Durvalumab in Combination With Chemotherapy in Completely Resected Stage II-III Non-small Cell Lung Cancer (NSCLC) (MERMAID-1). ClinicalTrials.gov identifier: NCT04385368. Updated October 27, 2022. Accessed January 24th, 2023. https://clinicaltrials.gov/ct2/show/NCT04385368

[17]Phase III Study to Determine Efficacy of Durvalumab in Stage II-III Non-small Cell Lung Cancer (NSCLC) After Curative Intent Therapy. (MERMAID-2). ClinicalTrials.gov Identifier: NCT04642469. Updated  October 19, 2022. Accessed January 24th, 2023. https://clinicaltrials.gov/ct2/show/NCT04642469