[Liquid biopsy analysis using cell-free DNA (cfDNA): Opportunities and limitations]

Transformation of ALK expression and PD-L1 0% to PD-L1 90% only after surgery: the need for rebiopsy in lung cancer patients

Lung cancer is still diagnosed at a late stage although novel diagnostic techniques are in use. However, as pharmacogenomics have evolved novel targeted therapies either with tyrosine kinase inhibitors or immunotherapy can be currently used as daily treatment. We present the case of a woman with anaplastic lymphoma-positive expression and programmed death-ligand 1 (PD-L1) 0% score upon diagnosis who underwent therapeutic surgery and represented PD-L1 90% expression, however, without anaplastic lymphoma kinase expression. Transformation of the tumor or new tumor is a question to be answered for this patient and possibly we should try and direct rebiopsies for this group of targeted therapy patients.

Benefit of everolimus as a monotherapy for a refractory breast cancer patient bearing multiple genetic mutations in the PI3K/AKT/mTOR signaling pathway

A postmenopausal patient with a diagnosis of estrogen receptor (ER) (+), progesterone receptor (PR) (+), and human epidermal growth factor receptor-2 (HER2) (-) breast cancer was reported. The patient refused surgery and was resistant to conventional chemotherapy regimens. Computed tomography and the circulating tumor cell test indicated that the patient’s tumor burden increased rapidly even after several chemotherapy sessions. Multiple genetic aberrances in the phosphatidylinositol3-kinases (PI3K) signaling pathway were detected via next-generation sequencing (NGS)-based liquid biopsy, including a p. G1007R missense mutation in exon 21 of PIK3CA (33.61%), a p.L70fs frameshift mutation in exon 3 of phosphatase and tension homolog deleted on chromosome ten (PTEN) (49.14%), and a p. D1542Y missense mutation in exon 32 of mammalian target of rapamycin (mTOR) (1.66%). Therefore, only the mTOR inhibitor everolimus was administered to the patient. Partial remission (PR) was observed after 2 months, and sustained stable disease (SD) was observed after a year and a half. Subsequent sequencing showed that the mutation ratio of PIK3CA decreased to 4.17%, and that the PTEN and mTOR mutations disappeared, which revealed the significant curative effect of everolimus. We report the first case of successful monotherapy treatment using everolimus in a patient with advanced breast cancer bearing mutations in genes involved in the PI3K/ARK/mTOR signaling pathway. The success of this case highlights the invaluable clinical contribution of NGS-based liquid biopsy, as it successfully provided an optimal therapeutic target for the patient with advanced breast cancer.