Collection of cell-free DNA (cfDNA) from the blood of individuals with cancer has permitted noninvasive tumor genome analysis. Detection and characterization of cfDNA in ascites and pleural effusions have not yet been reported. Herein, we analyzed cfDNA in the ascites and pleural effusions from six individuals with metastatic cancer. In all cases, cfDNA copy number variations (CNV) were discovered within the effusate. One individual had a relevant alteration with a high copy amplification in EGFR in a never smoker with lung cancer, who showed only MDM2 and CDK4 amplification in a prior tissue biopsy. Another subject with metastatic breast cancer had cytology-positive ascites and an activating PIK3CA mutation identified in the tissue, blood, and ascites collectively. This individual had tumor regression after the administration of the mTOR inhibitor everolimus and had evidence of chromotripsis from chromosomal rearrangements noted in the cell-free ascitic fluid. These results indicate that cfDNA from ascites and pleural effusions may provide additional information not detected with tumor and plasma cell-free DNA molecular characterization, and a context for important insights into tumor biology and clonal dynamic change within primary tumor and metastatic deposits. Mol Cancer Ther; 16(5); 948-55. Ó2017 AACR.

Sindbis virus (SV) is an alphavirus that causes acute encephalomyelitis in mice. The outcome is determined by the strain of virus and by the age and genetic background of the host. The mortality rates after infection with NSV, a neurovirulent strain of SV, were as follows: 81% (17 of 21) in BALB/cJ mice; 20% (4 of 20) in BALB/cByJ mice (P < 0.001); 100% in A/J, C57BL/6J, SJL, and DBA mice; and 79% (11 of 14) in immunodeficient scid/CB17 mice. Treatment with N-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthetase (NOS) inhibitor, increased mortality to 100% (P < 0.05) in NSV-infected BALB/cJ mice, to 95% (P < 0.001) in BALB/cByJ mice, and to 100% in scid/CB17 mice. BALB/cJ and BALB/cByJ mice had similar levels of inducible NOS mRNA in their brains, which were not affected by L-NAME or NSV infection. Brain NOS activity was similar in BALB/cJ and BALB/cByJ mice before and after infection and was markedly inhibited by L-NAME. NSV replication in the brains of BALB/cJ mice, BALB/cByJ mice, and mice treated with L-NAME was similar. Treatment of N18 neuroblastoma cells with NO donors S-nitroso-N-acetylpenicillamine or sodium nitroprusside in vitro before infection increased cell viability at 42 to 48 h compared with untreated NSV-infected N18 cells with little effect on virus replication. These data suggest that NO protects mice from fatal encephalitis by a mechanism that does not directly involve the immune response or inhibition of virus growth but rather may enhance survival of the infected neuron until the immune response can control virus replication.

Clinical-grade next-generation sequencing (NGS) of tissueand blood-derived circulating tumor DNA (ctDNA) allows assessment of multiple genomic alterations in patients with cancer. We analyzed ctDNA (54-70 genes) in 62 patients with advanced breast cancer (median ¼ five prior therapies); 38 also had tissue NGS (236-315 genes). Overall, 42 of 62 patients (68%) had detectable (characterized) ctDNA alterations (variants of unknown significance excluded), and 37 of 38 (97%) had tissue alterations. The median (range) number of characterized alterations in ctDNA was 1 (0-7), and in tissue, 4 (0-17). The most common alterations in ctDNA were in TP53 (37% of patients) and PIK3CA (23%), and for tissue, TP53 (37%) and PIK3CA (24%); EGFR amplification was seen in ctDNA (11%), but not in tissue. Concordance between ctDNA and tissue appeared higher if <6 months separated the sample acquisition, although small sample size precluded statistical validation. Overall, 32 of 67 tissue alterations (48%) were also detected in ctDNA; 35 of 72 ctDNA alterations (48%) were also in tissue. Excluding estrogen receptor and ERBB2, 41 of 62 patients (66%) had potentially actionable alterations in ctDNA, and 36 of 38 (95%), in tissue (with potential actionability based on either preclinical or clinical evidence). If !1 genomic alteration had ctDNA !5%, survival was shorter than if ctDNA was <5% (median, 6.7 vs. 17.9 months; P ¼ 0.01). In conclusion, tissue and ctDNA NGS reveal potentially actionable alterations in most patients. The genomic results of ctDNA and tissue NGS overlap, but there are differences, perhaps reflecting temporal spacing and tumor heterogeneity. ctDNA quantification also provides prognostic information.

The vast majority of patients with metastatic lung cancers who initially benefit from EGFR-targeted therapies eventually develop resistance. An increasing understanding of the number and complexity of resistance mechanisms highlights the challenge of treating tumors resistant to EGFR inhibitors. Resistance mechanisms include new, second-site mutations within EGFR (e.g., T790M and C797S), upregulation of MET kinase, upregulation of insulin growth factor receptor (IGFR), HER2 amplification, increased expression of AXL, BIM modulation, NF-κB activation, histologic switch to small-cell cancer, epithelial-to-mesenchymal transition, PDL1 expression with subsequent immune tolerance, and release of cytokines such as TGFβ and IL6. Herein, we review the growing body of knowledge regarding EGFR bypass pathways, and the development of new drugs and combination treatment strategies to overcome resistance. Mol Cancer Ther; 16(2); 265-72. ©2017 AACR.