e15095 Background: Immune checkpoint blockade is being used with increasing frequency across a variety of tumor types. Corticosteroids are used in diverse clinical scenarios and can have immune-modulatory effects. The administration of steroids with immune checkpoint blockade in combination with cytotoxic chemotherapy has not diminished treatment efficacy in select patient populations1. However, the effect of steroids on the development of immune-related adverse events (irAEs) across tumor types is unknown. We hypothesized that pretreatment with corticosteroids reduces treatment-limiting irAEs. Methods: A single institution registry of patients (n = 163) receiving immune checkpoint blockade, including anti-CTLA-4 antibody (n = 51) or anti-PD-1 antibody (n = 112), was reviewed. Various primary tumor types were included (33% melanoma, 31% non-small cell lung, 36% other). Patients were determined to have discontinued treatment because of irAEs versus any other cause (disease progression, infection, comorbidity, or death). Results: None of the 17 patients (0%) who were receiving corticosteroids prior to starting immunotherapy experienced treatment-limiting irAEs (average dose 34mg/day prednisone or equivalent, only one patient taking < 10mg/day prednisone). This is compared to 29 of 146 patients (19.9%) who were not taking steroids at the start of treatment (p = 0.045). Interestingly, pretreatment steroids were not associated with an increase in disease progression or death. Conclusions: Incidence of treatment-limiting immune-related adverse events was significantly decreased, regardless of tumor type, in patients receiving corticosteroids prior to initiation of immunotherapy. An associated decrease in treatment efficacy was not seen. Table: Incidence of treatment-limiting adverse events in patients undergoing immunotherapy Treatment-Limiting Adverse Events - n (%) Immune Infection or Comorbidity Disease Progression or Death Ongoing Treatment Total On Steroids When Immunotherapy Initiated? Yes 0 (0) 7 (41.1) 8 (47.1) 2 (11.8) 17 (100) No 29 (19.9) 19 (13.0) 71 (48.6) 27 (18.5) 146 (100) Total 29 (17.8) 26 (16.0) 79 (48.4) 29 (17.8) 163 (100)
Abstract Long-term air pollution (AP) exposure, including diesel exhaust exposure, is increasingly being recognized as a major contributor to the development of neurodegenerative diseases such as Parkinson’s and Alzheimer’s disease. How AP increases the risk of neurodegeneration is not well understood but might include direct neurotoxicity and CNS inflammation. We investigated the impact of diesel exhaust particulate extract (DEPe) exposure on the brain and the mechanisms by which microglia and astroglia might mediate neuronal changes. Zebrafish (ZF) were utilized to determine neuronal toxicity of and microglial response to DEPe and single cell RNA sequencing was employed to study cell type-specific transcriptomic responses within the ZF brain. DEPe exposure induced neuronal injury and microglial activation in vivo. However, preventing the development of microglia did not attenuate DEPe-induced neuron loss, leading us to investigate microglial, astroglial, and neuronal response to DEPe exposure at single-cell resolution. Differentially expressed genes and disease-relevant pathways were identified within glial and neuronal clusters after DEPe exposure. Microglia and astroglia existed in multiple states, some of which appear toxic and others protective to neurons. Neuronal transcriptomic analysis revealed that DEPe exposure reduced expression of autophagy-related genes consistent with direct neurotoxicity. In summary, DEPe exposure was neurotoxic in developing ZF larvae and induced neuroinflammation. The microglial inflammatory response did not contribute to neurotoxicity of DEPe and in fact, some glial clusters upregulated transcriptional pathways that are likely protective. Furthermore, DEPe exposure led to reduced expression of autophagy-related genes in neurons that likely contribute to its toxicity.
We are utilizing the Drosophila follicle cell gene amplification system to better understand the mechanisms of DNA replication origin activation in metazoans. During gene amplification, specific origins of replication undergo repeated rounds of activation at six distinct sites in the follicle cell genome. These Drosophila Amplicons in Follicle Cells ( DAFC s) utilize the same replication machinery as normal DNA replication, including the Origin Recognition Complex (ORC), DUP/Cdt1, and the MCM2–7 helicase. However, the mechanisms controlling the activation of amplification origins remain poorly understood. We identified an origin at DAFC‐62D whose activation is dependent upon transcription. We will present experiments utilizing transgenic DAFC‐62D transposon insertions to test whether transcription is required locally for origin activation. Additionally, we are investigating the effects of local chromatin on origin activation. We have identified cis ‐acting position effects acting over at least 5 kb that repress ORC binding and amplification at DAFC‐22B .
Precise DNA replication is crucial for genome maintenance, yet this process has been inherently difficult to study on a genome-wide level in untransformed differentiated metazoan cells. To determine how metazoan DNA replication can be repressed, we examined regions selectively under-replicated in Drosophila polytene salivary glands, and found they are transcriptionally silent and enriched for the repressive H3K27me3 mark. In the first genome-wide analysis of binding of the origin recognition complex (ORC) in a differentiated metazoan tissue, we find that ORC binding is dramatically reduced within these large domains, suggesting reduced initiation as one mechanism leading to under-replication. Inhibition of replication fork progression by the chromatin protein SUUR is an additional repression mechanism to reduce copy number. Although repressive histone marks are removed when SUUR is mutated and copy number restored, neither transcription nor ORC binding is reinstated. Tethering of the SUUR protein to a specific site is insufficient to block replication, however. These results establish that developmental control of DNA replication, at both the initiation and elongation stages, is a mechanism to change gene copy number during differentiation.
<p>PDF file - 1205K, Figure S7. Treatment of HER2 amplified cell lines with LJM716/ trastuzumab combinations is synergistic in a subset of cell lines.</p>
