Characterization of dermatitis after PD-1/PD-L1 inhibitor therapy and association with multiple oncologic outcomes: A retrospective case-control study.

BACKGROUND: Cutaneous adverse events are common with programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) inhibitors. However, the nature of the specific cutaneous adverse event of dermatitis has not been investigated across various PD-1/PD-L1 inhibitors. Oncologic outcomes potentially associated with dermatitis are not well characterized. OBJECTIVE: To assess the nature of dermatitis after exposure to a PD-1/PD-L1 inhibitor and oncologic outcomes associated with dermatitis. METHODS: Retrospective, matched, case-control study conducted at a single academic center. RESULTS: The most common histologic patterns were lichenoid dermatitis (50%) and spongiotic dermatitis (40%). The overall tumor response rate was 65.0% for the case patients and 17.0% for the controls (P = .0007) (odds ratio, 7.3; 95% confidence interval, 2.3-23.1). The progression-free survival and overall survival times were significantly longer for the case patients than for the controls by Kaplan-Meier analysis (P < .0001 and .0203, respectively). LIMITATIONS: The retrospective design and relatively small sample size precluded matching for all cancer types. CONCLUSIONS: Lichenoid and spongiotic dermatitis associated with PD-1/PD-L1 inhibitors could be a sign of robust immune response and improved oncologic outcomes. The value of PD-1/PD-L1-related dermatitis in predicting cancer outcomes awaits investigation through prospective multicenter studies for specific cancer types.

Discordance in routine second opinion pathology review of head and neck oncology specimens: A single-center five year retrospective review.

OBJECTIVES: Second opinion review of pathology specimens is a common institutional practice, supported by large retrospective studies demonstrating significant histologic discordance. Since the most recent study of head and neck-specific pathology review was conducted, routine HPV and EBV testing is now recommended for certain specimens. We describe the frequency of and reasons for discordant reports and their potential impact on treatment recommendations and prognosis in a five-year retrospective cohort study at a single academic referral institution from 2005 to 2010. MATERIALS AND METHODS: Following institutional review board review, 1003 cases referred to the Head and Neck Oncology Service were identified using a retrospective database search. Discordance between outside and second review pathology report was assessed by a board-certified medical oncologist. RESULTS: 667 cases were included, of which 22% were discordant. Discordance was associated with adenocarcinomas (AOR [adjusted odds ratio] 0.09, 95% CI 0.03-0.31; p<0.001), poorly differentiated carcinomas (AOR 0.14, 95% CI 0.06-0.39; p<0.001), and specimens of uncommon histology (AOR 0.18, 95% CI 0.07-0.45; p<0.001) but not biopsy site in a multivariate model. The most common reasons for discordance included histology (61%), followed by the results of special studies (36%), and the presence or absence of stromal invasion (14%). Differences in tumor HPV status comprised 16% of discordant cases and were associated with better prognosis (p<0.001) following second opinion review. CONCLUSIONS: Routine second opinion pathology review may lead to clinically significant differences in treatment recommendations and prognosis.

Acquiring snapshots of the orientation of trans-membrane protein domains using a hybrid FRET pair.

One challenge in studying the function of membrane-embedded proteins is determining the orientation of key domains in the context of the changing and dynamic membrane environment. We describe a confocal microscopy setup that utilizes external electric field pulses to direct dipicrylamine (DPA) to a membrane leaflet. The detection of FRET between DPA and a fluorescent probe attributes it to the inner or outer leaflet of a membrane. By utilizing short acquisition times and confocal imaging, this attribution could be made even in changing membrane environments. Our setup adds versatility to the study of the biological activity of membrane-embedded proteins.

Artificial membrane-like environments for in vitro studies of purified G-protein coupled receptors.

Functional reconstitution of transmembrane proteins remains a significant barrier to their biochemical, biophysical, and structural characterization. Studies of seven-transmembrane G-protein coupled receptors (GPCRs) in vitro are particularly challenging because, ideally, they require access to the receptor on both sides of the membrane as well as within the plane of the membrane. However, understanding the structure and function of these receptors at the molecular level within a native-like environment will have a large impact both on basic knowledge of cell signaling and on pharmacological research. The goal of this article is to review the main classes of membrane mimics that have been, or could be, used for functional reconstitution of GPCRs. These include the use of micelles, bicelles, lipid vesicles, nanodiscs, lipidic cubic phases, and planar lipid membranes. Each of these approaches is evaluated with respect to its fundamental advantages and limitations and its applications in the field of GPCR research. This article is part of a Special Issue entitled: Membrane protein structure and function.

Chemical kinetic analysis of thermal decay of rhodopsin reveals unusual energetics of thermal isomerization and hydrolysis of Schiff base.

The thermal properties of rhodopsin, which set the threshold of our vision, have long been investigated, but the chemical kinetics of the thermal decay of rhodopsin has not been revealed in detail. To understand thermal decay quantitatively, we propose a kinetic model consisting of two pathways: 1) thermal isomerization of 11-cis-retinal followed by hydrolysis of Schiff base (SB) and 2) hydrolysis of SB in dark state rhodopsin followed by opsin-catalyzed isomerization of free 11-cis-retinal. We solve the kinetic model mathematically and use it to analyze kinetic data from four experiments that we designed to assay thermal decay, isomerization, hydrolysis of SB using dark state rhodopsin, and hydrolysis of SB using photoactivated rhodopsin. We apply the model to WT rhodopsin and E181Q and S186A mutants at 55 °C, as well as WT rhodopsin in H(2)O and D(2)O at 59 °C. The results show that the hydrogen-bonding network strongly restrains thermal isomerization but is less important in opsin and activated rhodopsin. Furthermore, the ability to obtain individual rate constants allows comparison of thermal processes under various conditions. Our kinetic model and experiments reveal two unusual energetic properties: the steep temperature dependence of the rates of thermal isomerization and SB hydrolysis in the dark state and a strong deuterium isotope effect on dark state SB hydrolysis. These findings can be applied to study pathogenic rhodopsin mutants and other visual pigments.