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AbstractBackgroundOvercoming β-lactam resistance in pathogens such as Pseudomonas aeruginosa is a major clinical challenge. Rapid molecular diagnostics (RMDs) have the potential to inform selection of empiric therapy in patients infected by P. aeruginosa.MethodsIn this study, we used a heterogeneous collection of 197 P. aeruginosa that included multidrug-resistant isolates to determine whether 2 representative RMDs (Acuitas Resistome test and VERIGENE gram-negative blood culture test) could identify susceptibility to 2 newer β-lactam/β-lactamase inhibitor (BL-BLI) combinations, ceftazidime/avibactam (CZA) and ceftolozane/tazobactam (TOL/TAZO).ResultsWe found that the studied RMD platforms were able to correctly identify BL-BLI susceptibility (susceptibility sensitivity, 100%; 95% confidence interval [CI], 97%, 100%) for both BLs-BLIs. However, their ability to detect resistance to these BLs-BLIs was lower (resistance sensitivity, 66%; 95% CI, 52%, 78% for TOL/TAZO and 33%; 95% CI, 20%, 49% for CZA).ConclusionsThe diagnostic platforms studied showed the most potential in scenarios where a resistance gene was detected or in scenarios where a resistance gene was not detected and the prevalence of resistance to TOL/TAZO or CZA is known to be low. Clinicians need to be mindful of the benefits and risks that result from empiric treatment decisions that are based on resistance gene detection in P. aeruginosa, acknowledging that such decisions are impacted by the prevalence of resistance, which varies temporally and geographically.

e21038 Background: Several studies of advanced melanoma patients suggest that combining therapies that target tumor mechanisms of immune evasion with activation of normal immune cell functionality may provide optimal benefits for patients. The synthetic parasite derived GK1 peptide in combination with anti-PD-L1 showed significant longer survival (34 days) compared to GK1 or Anti-PD-L1 alone (23-27 days) in a murine melanoma model (p < 0.05). This means an increase survival increased in 47.82% in the mice treated with GK-1 + anti-PD-L1, 21.7% treated with GK-1, and 6.08% treated with anti-PD-L1. Methods: To elucidate the potential mechanism by which this combination treatment exerts its anti-melanoma effects, C57BL/6 mice were injected with B16-F10-luc2 cells and separated according to treatments in four groups: control, GK-1, anti-PD-L1 and GK-1/anti-PDL-1.Blood samples were collected at day 0, 14, and at euthanization or end of the experiment and monitored for serum cytokines using mice-specific V-PLEX Pro-inflammatory Panel. Results: On day 14, TNF-α levels in the Anti-PD-L1 and GK-1 therapy group was significantly lower compared to control mice. At sacrifice, the combined treatment group demonstrated significant decrease cytokine production in IL-6 and IL-10. Conclusions: The decreased cytokine levels observed in the GK-1/anti-PD-L1 group may explain the significant improved survival. GK-1 is a Th1 response inductor both in vitro and in vivo as it increases IFN-γ, IL-2 but not IL-4 and IL-10. It is noteworthy that when PD-L1 signaling is reduced in T cells these cells proliferate extensively in vitro and produce increased levels of IFN-γ and IL-17, suggesting an enhanced pro-inflammatory phenotype. It has been established that cytokines of Th2 response such as IL-4 and IL-5 and IL-6, have tumor-promoting activity. The anti-melanoma effect of the GK-1/anti-PD-L1 combination observed in the present study could be mediated by decreasing the pro-tumor Th2 response. These results provide novel alternative pathways and potential targets to enhance the clinical effect of the PD-1/PD-L1 blockade pathway.

9090 Background: We identified factors associated with better OS for previously treated, PD-L1–expressing advanced NSCLC using data from KEYNOTE-010 (NCT01905657; Herbst et al. Lancet. 2016;387:1540-50), in which pembrolizumab had superior OS over docetaxel. Methods: 1033 patients were randomly assigned 1:1:1 to pembrolizumab 2 or 10 mg/kg every 3 weeks (Q3W) or docetaxel 75 mg/m2 Q3W. Response was assessed per RECIST v1.1 by independent central review. Multivariate analyses were performed using a Cox proportional hazards regression model on OS in the pembrolizumab arms. A set of variable selection methods was applied to 19 baseline demographic and disease characteristics, including smoking status, and identified 7 factors that contributed to OS. Data cut was September 30, 2016. Results: Adjusted hazard ratios (HRs) for the factors in the pembrolizumab arm from the model are shown in the Table. Updated OS with an additional 6 months of follow-up from this data lock for KEYNOTE-010 will be presented. Conclusions: While the overall result of KEYNOTE-010 revealed improved OS with pembrolizumab compared with docetaxel in previously treated patients with PD-L1–positive advanced NSCLC, exploratory, post hoc multivariate analyses showed that some laboratory and tumor characteristics such as nonsquamous histology, normal baseline lactate dehydrogenase (LDH), PD-L1 TPS ≥50%, and wild-type EGFR mutation status were associated with better OS among patients treated with pembrolizumab. Clinical trial information: NCT01905657. [Table: see text]

530 Background: Therapeutic efficacy of H involves activation of the immune system.Age-dependent progressive deterioration of the immune response is referred as immunosenescence. In HER2+ breast cancer, the effects of aging and the ability of H to activate endogenous anti-tumor immunity is unknown. A previous report from HERA trial showed no significant increase in risk of early recurrence with age (≤ or > 40). We evaluated the long-term outcome of HER2+ patients (pt) related to age and immune landscape. Methods: 1,392 pt from N9831 trial were evaluated. Stromal tumor infiltrating lymphocytes (sTIL) were evaluated in H&E slides. Lymphocyte predominant breast cancer (LPBC) was defined as sTIL ≥ 50%. Molecular TIL (mTIL) and immune subset signatures were evaluated using NanoString research CodeSets. Cox proportional hazard ratio (HR) was used for analysis. Results: There were 1,111 (79.8%) pt > 40 years old (yo) and 281 (20.2%) pt ≤ 40 yo. Younger age was significantly associated with hormone receptor positivity (p 0.00011) and luminal B subtype (p 0.011). With a median follow up of 10.6 years, there was no significant difference in long-term outcome among pt ≤ 40 vs. > 40 yo who received H (HR = 0.88 (0.62-1.24), p = 0.45). Similar findings were observed when age was dichotomized at 50 and 60 yo. While there was no association between sTIL and age, a small but significant increase in mTIL CD45 expression with age (p 0.003) was observed. Similar small increases in cytotoxic cell (p 0.007) and T cell (p 0.015) immune scores were also observed with increasing age. Among pt who received chemotherapy alone, pt > 40 yo with LPBC (n 55) had excellent outcome with 92.4% recurrence free survival (RFS) at 10 years. However, there was no significant difference in RFS among pt ≤ 40 yo with or without LPBC. Conclusions: Among pt treated with H, there was no significant difference in outcome related to age. In contrast to a decline expected from immunosenescence, we observed small but significant increases in mTIL signatures for total lymphocytes, cytotoxic, and T cell subsets. Among patients who received chemotherapy alone, our data suggested that pt > 40 yo with LPBC had excellent prognosis, compared to pt > 40 yo without LPBC.