Purpose Tumor-infiltrating lymphocytes (TILs) in the residual disease (RD) of triple-negative breast cancers (TNBCs) after neoadjuvant chemotherapy (NAC) are associated with improved survival, but insight into tumor cell-autonomous molecular pathways affecting these features are lacking. Experimental Design We analyzed TILs in the RD of clinically and molecularly characterized TNBCs after NAC and explored therapeutic strategies targeting combinations of MEK inhibitors with PD-1/PD-L1-targeted immunotherapy in mouse models of breast cancer. Results Presence of TILs in the RD was significantly associated with improved prognosis. Genetic or transcriptomic alterations in Ras/MAPK signaling were significantly correlated with lower TILs. MEK inhibition up-regulated cell-surface major histocompatibility complex (MHC) expression and PD-L1 in TNBC cells both in vivo and in vitro. Moreover, combined MEK and PDL-1/PD-1 inhibition enhanced anti-tumor immune responses in mouse models of breast cancer. Conclusions These data suggest the possibility that Ras/MAPK pathway activation promotes immune-evasion in TNBC, and support clinical trials combining MEK- and PD-L1-targeted therapies. Furthermore, Ras/MAPK activation and MHC expression may be predictive biomarkers of response to immune checkpoint inhibitors.

Patients with stages I, II, and III SCLC, who underwent surgical resection as part of initial treatment with chemotherapy had respectable OS. These data may warrant prospective studies of including surgery in the multimodality treatment of SCLC in specific circumstances.

Amplifications at 9p24 have been identified in breast cancer and other malignancies, but the genes within this locus casually associated with oncogenicity or tumor progression remain unclear. Targeted next-generation sequencing of post-chemotherapy triple-negative breast cancers (TNBC) identified a group of 9p24-amplified tumors, which contained focal amplification of the Janus kinase-2 (JAK2) gene. These patients had markedly inferior recurrence-free and overall survival compared to patients with TNBC without JAK2 amplification. Presence of JAK2/9p24 amplifications occurred at higher rates in chemotherapy-treated TNBCs than in untreated TNBCs or basal-like breast cancers, or in other subtypes. Similar rates of JAK2 amplification were confirmed in patient-derived TNBC xenografts. In patients where longitudinal specimens were available, JAK2 amplification was selected for during neoadjuvant chemotherapy and eventual metastatic spread, suggesting a role in tumorigenicity and chemoresistance, phenotypes often attributed to a cancer stem-like cell population. In TNBC cell lines with JAK2 copy gains or amplification, specific inhibition of JAK2-STAT6 signaling reduced mammosphere formation and cooperated with chemotherapy in reducing tumor growth in vivo. In these cells, inhibition of JAK1-STAT3 signaling had little effect or, in some cases, counteracted JAK2-specific inhibition. Collectively, these results suggest that JAK2-specific inhibitors are more efficacious than dual JAK1/2 inhibitors against JAK2-amplified TNBCs. Furthermore, JAK2 amplification is a potential biomarker for JAK2-dependence which, in turn, can be used to select patients for clinical trials with JAK2 inhibitors.

Neisseria meningitidis, a causative agent of bacterial meningitis, has a relatively small repertoire of transcription factors, including NMB0573 (annotated AsnC), a member of the LrpAsnC family of regulators that are widely expressed in both Bacteria and Archaea. In the present study we show that NMB0573 binds to L-leucine and L-methionine and have solved the structure of the protein with and without bound amino acids. This has shown, for the first time that amino acid binding does not induce significant conformational changes in the structure of an AsnC/Lrp regulator although it does appear to stabilize the octameric assembly of the protein. Transcriptional profiling of wild-type and NMB0573 knock-out strains of N. meningitidis has shown that NMB0573 is associated with an adaptive response to nutrient poor conditions reflected in a reduction in major surface protein expression. On the basis of its structure and the transcriptional response, we propose that NMB0573 is a global regulator in Neisseria controlling responses to nutrient availability through indicators of general amino acid abundance: leucine and methionine.The L-leucine-responsive regulatory protein (Lrp) 2 /AsnC family of transcription factors are widely distributed in both Bacteria and Archaea but do not appear to be present in eukaryotic genomes. The family is named after two proteins from Escherichia coli implicated in the control of amino acid metabolism; the Lrp and AsnC, which share ϳ25% sequence identity. Lrp is a global regulator that controls the expression of a large number of operons in E. coli, including those involved in the synthesis and degradation of amino acids (1), whereas AsnC is a specific regulator of the asnA gene, which codes for asparagine synthetase, responsible for converting aspartate to asparagine in an ATP-dependent reaction, and an autorepressor of its own expression (2). As the name implies, many Lrp-responsive operons are co-regulated by L-leucine that can either antagonize or potentiate the effects of Lrp (3). L-Leucine is one of the most common amino acids in proteins and the reciprocal effect of Lrp on amino acid metabolism suggests that intracellular Lrp abundance mediates transitions between "feast and famine" (3, 4). AsnC, on the other hand, appears to be responsible for controlling asparagine levels via negative feedback regulation of asparagine synthetase expression (2, 5).Insight into the relationship between the structure of Lrp/ AsnC family proteins and their function has come from x-ray crystallography. To date, four x-ray crystal structures from the family have been reported, two from Archaeal sources; Pyrococcus furiosus LrpA (Protein Data Bank code 1I1G (6) and the close homologue, FL11, from Pyrococcus sp. OT3 (PDB code 1RI7 (7) and two from bacterial sources: E. coli AsnC in complex with asparagine (PDB code 2CG4) and Bacillus subtilis LrpC (PDB code 2CFX) (8). The Lrp/AsnC family fold revealed by analysis of these structures consists of a N-terminal DNAbinding domain containing a helix-turn-helix ...