Fig. 5.

A representative case where the changes in ctDNA concentration of CSF and plasma samples reflected the responses of intracranial and extracranial tumors, respectively. P76 had unique genetic alterations in baseline CSF and plasma samples, and received paclitaxel combined with cisplatin as the first-line treatment. At 8 weeks after two cycles of treatment, a partial response was achieved in the thoracic lesion according to CT scans, while disease progressed in intracranial lesions according to brain MRIs. CSF ctDNA concentrations increased and plasma ctDNA concentrations decreased respectively. Abbreviations: CSF, cerebrospinal fluid; NGS, next-generation sequencing; PD, progression disease; PR, partial response