A delayed treatment model for the evaluation of scopolamine for VX nerve agent intoxication

Most research on medical countermeasures for nerve agent exposure assumes a military scenario, in which (autoinjector) treatment is envisaged to be available immediately. In a civilian setting however, treatment is delayed until arrival of first-aid responders. This may significantly affect treatment efficacy and the requirements for secondary intensive care. The aim of the current study was to develop a guinea pig model to evaluate the efficacy of delayed treatment following nerve agent exposure. We identified a trigger-to-treat based on a progressive stage of the toxidrome following VX exposure, which was associated with the subsiding of clonic movements. This paradigm resulted in treatment consistently being administered between 15 and 25 min post-exposure. Using the model, we investigated the potential for the anticholinergic scopolamine to act as a delayed treatment either as a standalone treatment, or as an adjunct to delayed treatment with Standard of Care (SOC), containing atropine, 2-PAM, and midazolam. The study provides a framework for a small animal model for evaluating the efficacy of treatment administered at a specific stage of the toxidrome, when immediate treatment is absent. As an adjunct, scopolamine treatment did not result in improved survival, but did show a beneficial effect on recovery, in terms of general posture. As a standalone treatment, scopolamine showed a significant, dose-responsive, beneficial effect on survival and recovery. These promising results warrant additional studies to investigate which observed physiological improvements are relevant for the recovery process and residual injury.

The pharmacokinetics of ketamine following intramuscular injection to F344 rats

Ketamine is a glutamate N-methyl-D-aspartate receptor antagonist that is a rapid-acting dissociative anesthetic. It has been proposed as an adjuvant treatment along with other drugs (atropine, midazolam, pralidoxime) used in the current standard of care (SOC) for organophosphate and nerve agent exposures. Ketamine is a pharmaceutical agent that is readily available to most clinicians in emergency departments and possesses a broad therapeutic index with well-characterized effects in humans. The objective of this study was to determine the pharmacokinetic profile of ketamine and its active metabolite, norketamine, in F344 rats following single or repeated intramuscular administrations of subanesthetic levels (7.5 mg/kg or 30 mg/kg) of ketamine with or without the SOC. Following administration, plasma and brain tissues were collected and analyzed using a liquid chromatography-mass spectrometry method to quantitate ketamine and norketamine. Following sample analysis, the pharmacokinetics were determined using non-compartmental analysis. The addition of the current SOC had a minimal impact on the pharmacokinetics of ketamine following intramuscular administration and repeated dosing at 7.5 mg/kg every 90 minutes allows for sustained plasma concentrations above 100 ng/mL. The pharmacokinetics of ketamine with and without the SOC in rats supports further investigation of the efficacy of ketamine co-administration with the SOC following nerve agent exposure in animal models.

Real-world evidence analysis of palbociclib prescribing patterns for patients with advanced/metastatic breast cancer treated in community oncology practice in the USA one year post approval

Background

Rapidly evolving understanding of cancer biology has presented novel opportunities to translate that understanding into clinically relevant therapy. Palbociclib, a novel, first-in-class cyclin-dependent kinase (CDK) 4/6 inhibitor was approved in the USA in February 2015 for the treatment of advanced/metastatic breast cancer. We examined real-world evidence in the first year post approval to understand the clinical and demographic characteristics of patients treated with palbociclib in community oncology practices and the dosing, treatment, and complete blood count (CBC) monitoring patterns.

Methods

This was a retrospective observational study of structured data from a US electronic medical record (EMR) database. Female patients receiving palbociclib after 31 January 2015 were followed through 31 March 2016. Our methodological rules were constructed to aggregate drugs received according to the order in which they are given, i.e., identify the line of therapy as first, second, or third line, etc., using treatment order and course description fields from the EMR.

Results

There were 763 patients initiating palbociclib who met the selection criteria. Of those, 612 (80.2%) received palbociclib concomitantly with letrozole. Mean follow up was 6.4 months and mean age at palbociclib initiation was 64 years. Of patients with a known starting dose (n = 417), 79.9% started on palbociclib 125 mg. Dose reductions were observed in 20.1% of patients. Percentages of patients according to line of therapy at initiation of palbociclib were first-line, 39.5%; second-line, 15.7%; third-line, 13.1%; and fourth-line therapy or later, 31.7%. On average, two CBC tests were conducted during the first cycle of palbociclib treatment. Overall, 74.6% of patients had a neutropenic event during follow up including 47.3% and 8.0% of patients with a grade 3 or 4 occurrence, respectively.

Conclusions

Real-world palbociclib use one year post US approval demonstrates a more heterogeneous patient population than that studied in the clinical trials with more than half of the patients receiving palbociclib plus letrozole in later lines of therapy. CBC testing rates suggested good provider compliance with monitoring guidelines in the USA prescribing information. The occurrence of grade 3 and 4 neutropenia (based on laboratory results) was consistent with the rates of grade 3 and 4 neutropenia in two phase-III studies (PALOMA-2, 56% and 10%; PALOMA-3, 55% and 11%, respectively). Understanding palbociclib utilization in real-world patients and how drug dosing and monitoring are performed aids in the understanding of safe and effective use of the drug.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-0958-2) contains supplementary material, which is available to authorized users.

Abstract P6-16-05: Early utilization pattern of palbociclib 1 year post-approval in the United States

Background

Palbociclib was approved in the U.S. in February 2015 for the treatment of advanced/metastatic breast cancer (MBC) in combination with letrozole as initial endocrine based therapy for post-menopausal women with ER+/HER2- disease. We examined the demographic, clinical characteristics and treatment patterns of patients initiating palbociclib (PAL) + letrozole (LET) in real-world, community oncology practices.

Methods

This was a retrospective observational study of female breast cancer patients identified in the Navigating Cancer (NC) EMR database. The NC database collects EMR data, in both structured and unstructured fields (patient/clinical progress notes), from over 975 oncology and hematology providers across more than 50 locations in 25 states. Female patients with record of treatment with PAL after 01/31/2015 were selected. Combination treatment with LET was defined as having a record for LET within 30 days of the PAL prescription. Line of therapy (LOT) was assessed from the date of metastatic diagnosis and assigned by evaluating treatment plans pre-and post PAL initiation. Bi-monthly cohorts were constructed based on the month of initiation of PAL from 02/01/2015-01/31/2016. Interim results are presented; data from an additional three months of follow-up (through 03/31/2016) are pending.

Results

Overall, 931 unique patients were identified as having initiated PAL treatment. Of those, 608 (65.3%) received PAL + LET. Mean follow-up was relatively short at 5.4 mo (SD=3.5). Confirmed ER+/HER2- was observed in 71.6% of patients and 50.3% were age ≥65, mean age was 64.3 yrs. Of patients with available ECOG-PS at treatment initiation (n=424): 0/1=78.5%, 2=17.5% and 3=4.0%. Of patients with a known starting dose (n=418), 69.9% initiated with PAL 125mg, 22.0% at 100mg and 8.1% at 75mg. Compared to women < 65, women ≥ 65 were more often started with 100mg (25.4% vs. 18.9%) and 75mg (10.0% vs 6.5%). Any dose reductions were observed in 20.6% of patients (21.5% of patients receiving 125mg). During the year following approval, 39.8% of patients initiated PAL + LET at LOT1, 15.6% at LOT2, 13.0% at LOT3 and 31.6% at LOT4+, following MBC diagnosis. Over time the proportion of late use (LOT4+) declined from 39.7% in Feb/Mar '15 to 23.9% in Dec '15/Jan '16 with more patients utilizing in LOT3 (from 7.9% in Feb/Mar '15 to 19.5% in Dec '15/Jan '16).

Number of Patients Initiating PAL + LET by LOT and Month. AllFeb/Mar '15Apr/May '15Jun/Jul '15Aug/Sep '15Oct/Nov '15Dec'15/Jan '16N (%)608(100)63(10.4)108(17.8)125(20.6)108(17.8)91(14.5)113(18.6)LOT1 (%)242(39.8)23(36.5)45(41.7)53(42.4)45(41.7)33(36.3)43(38.1)LOT2 (%)95(15.6)10(15.9)12(11.1)19(15.2)15(13.9)18(19.8)21(18.6)LOT3 (%)79(13.0)5(7.9)10(9.3)18(14.4)12(11.1)12(13.2)22(19.5)LOT4+ (%)192(31.6)25(39.7)41(38.0)35(28.0)36(33.3)28(30.8)27(23.9)

Conclusions

There was a trend toward earlier utilization of PAL + LET from Feb-Jul '15, an increase in later use during Aug/Sep '15, and a return towards earlier use in subsequent cohorts reaching the lowest proportion of LOT 4+ use observed in Dec '15/Jan '16. After a mean follow-up of 5.4 mo, 21.5% of patients receiving the 125 mg dose had a dose reduction. Final results, with additional follow-up, will be presented at conference.

Citation Format: Kish JK, Ward MA, Garofalo D, Ahmed HV, McRoy L, Laney J, Zanotti G, Yu H-T, Feinberg BA. Early utilization pattern of palbociclib 1 year post-approval in the United States [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-16-05.

The Saccharomyces cerevisiae ubiquitin-proteasome system

Our studies of the yeast ubiquitin-proteasome pathway have uncovered a number of general principles that govern substrate selectivity and proteolysis in this complex system. Much of the work has focused on the destruction of a yeast transcription factor, MAT alpha 2. The alpha 2 protein is polyubiquitinated and rapidly degraded in alpha-haploid cells. One pathway of proteolytic targeting, which depends on two distinct endoplasmic reticulum-localized ubiquitin-conjugating enzymes, recognizes the hydrophobic face of an amphipathic helix in alpha 2. Interestingly, degradation of alpha 2 is blocked in a/alpha-diploid cells by heterodimer formation between the alpha 2 and a1 homeodomain proteins. The data suggest that degradation signals may overlap protein-protein interaction surfaces, allowing a straightforward steric mechanism for regulated degradation. Analysis of alpha 2 degradation led to the identification of both 20S and 26S proteasome subunits, and several key features of proteasome assembly and active-site formation were subsequently uncovered. Finally, it has become clear that protein (poly) ubiquitination is highly dynamic in vivo, and our studies of yeast de-ubiquitinating enzymes illustrate how such enzymes can facilitate the proteolysis of diverse substrates.