Objectives
To evaluate the antimicrobial and synergistic (hypothetically due to the inhibition of efflux pumps) effects of selective serotonin reuptake inhibitors (SSRIs) in Escherichia coli strains ...overproducing various resistance-nodulation-division (RND) efflux pumps.
Methods
MICs of various SSRIs and of clinically relevant antibiotics in the presence and absence of sertraline were determined for E. coli strains overproducing the RND efflux pumps AcrAB, AcrEF, MdtEF and MexAB. The effect of sertraline on Nile red efflux was evaluated in a real-time efflux assay. Expression of marA and acrB was monitored using quantitative RT-PCR.
Results
In MIC assays there was limited synergy of sertraline with tetracycline, oxacillin, linezolid and clarithromycin, depending on the individual pump overexpressed and on whether rich or minimal medium was used. Sertraline, as the most potent SSRI with regard to bacterial growth inhibition, led to rapid dose-dependent Nile red efflux inhibition, and was also found to increase the expression of marA and acrB.
Conclusions
A possible explanation for the discrepancy between the MIC and real-time efflux assays was that sertraline is a weak inducer of marA and acrB, thereby reducing its initial antibacterial and sensitizing effects over time. The results indicate that sertraline may be useful as a model efflux pump inhibitor for in vitro short-term experiments in E. coli, but is unlikely to be clinically useful as a co-drug against Gram-negative bacteria.
To evaluate the importance of phenylalanine residues for substrate transport in the Escherichia coli efflux pump protein AcrB, we subjected Phe-to-Ala binding pocket mutants to a real-time efflux ...assay with the novel near-infrared lipophilic membrane probe 1,2'-dinaphthylamine (1,2'-DNA). All mutations, with the exception of F617A, led to considerable retardation of efflux. F610A was the point mutation with the most pronounced impact, followed by F628A, F615A, F136A, and F178A. This is the first study to demonstrate the importance of single phenylalanine residues within the AcrB binding pocket for real-time substrate transport.
Introduction: Over the last decade MM diagnosis and therapy have greatly improved; notably due to an increasing number of “novel agents” (NA; e.g. PIs, IMiDs, mAbs, HDAC-, PD1/PD-L1-inhibitors). ...Anti-MM-therapy has gained complexity; orientation towards “state of the art” chemotherapy (CTx) protocols and international guidelines, as well as their continuous evaluation is highly important. According to the international literature, analyses of CTx management and particularly the use of novel substances have mainly been performed in the context of clinical trials (CT), therefore in a selected minority of patients (pts). In order to determine, whether guideline recommendations on MM therapy are thoroughly implemented in- and outside CT settings, we performed a real-world data analysis on clinical MM practice patterns. Substance use was analyzed in view of treatment lines and evaluated for “MM-pathway conformity”.
Methods: We performed a detailed analysis of 287 myeloma pts treated at our University Medical Center, part of the DSMM study group in 2014/15. The pt cohort was defined using the hospital pharmacy and tumor documentation (TBD) databases. TBD analysis enabled the detailed acquisition of pt characteristics, such as age at initial diagnosis (ID), gender, Durie and Salmon (D&S) and International Staging System stage (ISS). Status of transplantation (Tx), comorbidity (via Revised Myeloma Comorbidity Index R-MCI), CT data, treatment line/cycle and the year of CTx application were collected using electronic medical records, TBD and CTx management tools. Basic data on therapy composition was collected for the years 2005 to 2017, separating two treatment periods for 1st, 2nd and 3rd-line therapy of 2005-2012 and 2013-2017. This cut-off was carefully chosen to discriminate best between NA- and non-NA-based regimens, and between first generation PI- (bortezomib (BOR) and IMiD-use (thalidomide (THAL), lenalidomide (LEN)) and second generation NA.
Results: Pt characteristics were representative for tertiary centers with a median age of 63 years (27-89), 54% were 60-79 and 14% >80 years old. The male:female gender ratio was 58%:42% and ISS predominantly advanced (II/III:62%). Pts showed substantial comorbidities and were classified as fit, intermediate-fit and frail according to R-MCI in 33%, 56% and 11%, respectively. Of interest, 33% of pts could be enrolled in CTs and 88% received 1st line treatment at our center. 275 pts received 1st-line, 149 pts 2nd-line and 97 pts 3rd-line treatment (Fig.1). As expected, numbers of pts decreased with subsequent lines of treatment, albeit the median time to 2nd line therapy due to progression amounted to 2 years. As depicted in Fig.1, 1st line conventional CTx (cCTx) alone was rare and substantially declined over time from 12% 2005-2012 to 1% in 2013-2017. 200 pts (73%) were treated with BOR in 1st line, 63 of 106 reinduced pts received BOR in 2nd or 3rd line. IMiD 2nd and 3rd line treatment was also common within different regimens and the combination of 2 NA of both PI+IMiD increased over time (BOR+THAL, BOR+LEN). The use of second generation NA in 2nd and 3rd line treatment notably increased in 2013 to 2017 in line with their approval. Our analysis revealed that 44% of second generation NA protocols were administered outside CT settings, mainly due to tight inclusion and wide CT exclusion criteria. Maintenance was performed in 57% of pts, predominantly with LEN (60%) and within DSMM CT protocols.
Conclusion: Our analyses demonstrate that NA combinations are used predominantly today, whereas the use of cCTx alone is substantially declining. While BOR plays an important role in induction, LEN was subsequently used for maintenance and in outpatient-regimens. BOR-reinduction as a validated treatment option is also reflecting the substantial amount of BOR-based protocols worldwide. A significant percentage of second generation NA are administered outside CT settings, representing the fast and effective implementation of guideline recommendations into the real-world clinical practice at our and other MM centers. Currently, we are assessing the percentage of pts discussed in our weekly MM tumorboard, the evidence level of therapeutic interventions, PFS and OS. Results will be shown at the meeting, including the comparison of our data with others in a detailed review of the literature.
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Engelhardt:German Cancer Aid (#11424): Other: Educational Grant; Janssen Cilag GmbH: Other: Educational Grant; Celgene GmbH: Other: Educational Grant; Amgen GmbH: Other: Educational Grant.
Carfilzomib Engelhardt, Monika; Szymaniak-Vits, Magdalena; Ajayi, Stefanie ...
Recent results in cancer research,
2018, Volume:
212
Journal Article
Peer reviewed
Carfilzomib (CFZ) is a potent, second-generation proteasome inhibitor (PI), with significant activity as a single agent and in combination with other antimyeloma agents in patients with relapsed or ...refractory multiple myeloma (RRMM). CFZ binds selectively and irreversibly to its target and leads to antiproliferative and proapoptotic effects on cancer cells. This irreversible inhibition is dose- and time-dependent in vitro and in vivo. CFZ as monotherapy and in combination with other antimyeloma agents (e.g., as CFZ and dexamethasone Kd) achieved very good responses, progression-free survival (PFS) and overall survival (OS). In several ongoing studies, CFZ is being investigated in triplet and quadruplet schedules of CFZ, lenalidomide and dexamethasone (KRd), CFZ, cyclophosphamide, dexamethasone (KCd) and with antibodies, like elotuzumab or daratumumab. The multitude of completed and ongoing studies confirmed a tolerable safety profile of CFZ, a significantly lower incidence of neuropathy compared to bortezomib (BTZ) and a slightly higher incidence of cardiotoxicity, which is closely observed and precautions taken to avoid them as best as possible. In July 2012, the US Food and Drug Administration (FDA) approved CFZ as a single agent for RRMM patients with disease progression after two prior therapies, including BTZ and immunomodulatory drugs (IMiDs). The combination of KRd and Kd followed, being approved by both FDA and European Medicines Agency (EMA) in 2015 and 2016, respectively. Moreover, CFZ is being evaluated in patients with newly diagnosed MM (NDMM), in high-risk smoldering MM and for maintenance approaches.
Antimicrobial peptides (AMPs) are effector molecules of innate immunity. To determine whether AMP susceptibility of
S. aureus varies according to different types of infection, 102 isolates from ...patients with
S. aureus bacteremia or recurrent skin and soft tissue infection, and colonizing isolates were investigated. Using microbroth dilution assays we found a narrow range of MICs of human β-defensin-3, cathelicidin LL-37 and bovine indolicidin without significant differences between the groups. Colony-forming unit (CFU) assays revealed minor differences in bactericidal activity with slightly but not significantly higher CFU reduction in colonizing isolates. These data do not support a role for differential AMP susceptibility in vitro as a major determinant of
S. aureus invasive infection.
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