Detection of Discrepant Driver Mutations in a Patient with Two Synchronous Primary Non-Small Cell Lung Cancers (NSCLCs) with Liquid Biopsy

Acquired G2032R Resistance Mutation in ROS1 to Lorlatinib Therapy Detected with Liquid Biopsy

Lorlatinib, a third-generation anaplastic lymphoma kinase (ALK)/receptor tyrosine kinase inhibitor (ROS1), demonstrated efficacy in ROS1 positive (ROS1+) non-small cell lung cancer (NSCLC), although approval is currently limited to the treatment of ALK+ patients. However, lorlatinib-induced resistance mechanisms, and its efficacy against the resistance mutation G2032R in ROS1, respectively, have not yet been fully understood. Furthermore, concomitant tumor suppressor gene p53 (TP53) mutations occur in driver alteration positive NSCLC, but their prognostic contribution in the context of ROS1 inhibition remains unclear. Here we report a ROS1+ NSCLC patient who developed an on target G2032R resistance mutation during second-line lorlatinib treatment, indicating the lack of activity of lorlatinib against ROS1 G2032R. The resistance mutation was detected in plasma-derived ctDNA, signifying the clinical utility of liquid biopsies.

Quantitative Analysis and Monitoring of EZH2 Mutations Using Liquid Biopsy in Follicular Lymphoma

Recent advances in molecular technologies enable sensitive and quantitative assessment of circulating tumor DNA, offering a noninvasive disease monitoring tool for patients with malignant disorders. Here, we demonstrated on four follicular lymphoma cases that circulating tumor DNA based EZH2 mutation analysis performed by a highly sensitive droplet digital PCR method may be a valuable treatment monitoring approach in EZH2 mutant follicular lymphoma. EZH2 variant allele frequencies changed in parallel with the volume of metabolically active tumor sites observed on 18F-fluorodeoxyglucose positron emission tomography combined with computer tomography (PET-CT) scans. Variant allele frequencies of EZH2 mutations decreased or were eliminated rapidly upon successful treatment, with treatment failure being associated with elevated EZH2 variant allele frequencies. We also demonstrated spatial heterogeneity in a patient with two different EZH2 mutations in distinct anatomical sites, with both mutations simultaneously detected in the liquid biopsy specimen. In summary, circulating tumor DNA based EZH2 mutation analysis offers a rapid, real-time, radiation-free monitoring tool for sensitive detection of EZH2 mutations deriving from different anatomical sites in follicular lymphoma patients receiving immunochemotherapy.

Liquid biopsy assessment of synchronous malignancies: a case report and review of the literature

Assessment of patients with synchronous primary cancers and metastases is challenging, as it can be difficult to assign the metastases to the correct primary due to low differentiation, high similarity on histology or inaccessibility of tumour tissue. Systemic treatment for metastatic disease, however, needs to be directed at the leading histology or cover multiple tumour types with the same regimen. Considering the additional obstacles in cancer management, including tumour heterogeneity and clonal evolution, blood-based genomic profiling (‘liquid biopsy’) is suggested to be a useful tool to provide accessible tumour-derived biomarkers. We herein report a case of a patient with independent primary tumours of the colon and pancreas, as well as liver metastases. All lesions were resected and genotyped revealing KRAS mutations G12C and G12D in the primary tumours, respectively. The G12D mutation detected in the pancreatic tumour was retrieved in the metastasis, thus confirming the pancreatic cancer to be the origin of the liver lesions. The prevalence of the pancreatic tumour was additionally verified by the detection of the G12D variant in circulating cell-free DNA (cfDNA). This case demonstrates the utility of liquid biopsy to identify the predominant tumour burden in patients with multiple primary cancers, based on the detection of the tumour-associated gene mutation in the plasma. Serial monitoring through liquid biopsies might allow disease surveillance to guide cancer management. The review of the literature highlights the importance of liquid biopsies in personalised oncology, even though only one case report refers to the benefit of cfDNA analysis in a patient affected by synchronous primary tumours.