Etoposide is a semisynthetic, chemotherapeutic drug widely recommended to treat an extensive range of human cancers. Our studies indicate that, while etoposide is capable of killing human cancer cells, exposure to single-walled carbon nanotubes (SWCNTs) and etoposide results in enhanced cell death that appears to be synergistic and not merely additive. In this study, we used high pressure liquid chromatography and mass spectrometry to quantify the internal effective dose of etoposide when the human pancreatic cancer cell (PANC-1) was exposed to the combination of these agents. Our results unequivocally indicate that SWCNTs improve etoposide uptake and increase its capacity to kill cancer cells. We suggest that a combination of SWCNTs and etoposide may prove to be a more efficient chemotherapeutic protocol, especially because of the potential to lower toxic drug doses to levels that may be useful in decreasing adverse side effects, as well as in lowering the probability of inducing chemoresistance in exposed cancer cells.

Clinical laboratories routinely use formalin-fixed paraffin-embedded (FFPE) tissue or cell block cytology samples in oncology panel sequencing to identify mutations that can predict patient response to targeted therapy. To understand the technical error due to FFPE processing, a robustly characterized normal cell line was used to create FFPE samples with four different pre-tissue processing formalin fixation times. A total of 96 FFPE sections were then distributed to different laboratories for targeted sequencing analysis by four oncopanels, and variants resulting from technical error were identified. Tissue sections that failed more frequently showed low cellularity, lower than recommended library preparation DNA input, or target sequencing depth. Importantly, sections from block surfaces were more likely to show FFPE-specific errors, akin to “edge effects” seen in histology, and the depth of formalin damage was related to fixation time. To assure reliable results, we recommend avoiding the block surface portion and restricting mutation detection to genomic regions of high confidence.