Ex Vivo Profiling of PD-1 Blockade Using Organotypic Tumor Spheroids

Ex vivo systems that incorporate features of the tumor microenvironment and model the dynamic response to immune checkpoint blockade (ICB) may facilitate efforts in precision immuno-oncology and the development of effective combination therapies. Here, we demonstrate the ability to interrogate ex vivo response to ICB using murine- and patient-derived organotypic tumor spheroids (MDOTS/PDOTS). MDOTS/PDOTS isolated from mouse and human tumors retain autologous lymphoid and myeloid cell populations and respond to ICB in short-term three-dimensional microfluidic culture. Response and resistance to ICB was recapitulated using MDOTS derived from established immunocompetent mouse tumor models. MDOTS profiling demonstrated that TBK1/IKKε inhibition enhanced response to PD-1 blockade, which effectively predicted tumor response in vivo Systematic profiling of secreted cytokines in PDOTS captured key features associated with response and resistance to PD-1 blockade. Thus, MDOTS/PDOTS profiling represents a novel platform to evaluate ICB using established murine models as well as clinically relevant patient specimens.Significance: Resistance to PD-1 blockade remains a challenge for many patients, and biomarkers to guide treatment are lacking. Here, we demonstrate feasibility of ex vivo profiling of PD-1 blockade to interrogate the tumor immune microenvironment, develop therapeutic combinations, and facilitate precision immuno-oncology efforts. Cancer Discov; 8(2); 196-215. ©2017 AACR.See related commentary by Balko and Sosman, p. 143See related article by Deng et al., p. 216This article is highlighted in the In This Issue feature, p. 127.

Abstract 3236: Small molecule inhibitors of choline kinase lead to reduced phosphocholine levels and induction of apoptosis in cancer cells

Choline Kinase (ChoK) catalyzes the synthesis of phosphocholine (pCho) as the first step in the Kennedy pathway towards synthesis of the major membrane phospholipid, phosphatidylcholine. Increased phosphorylation of choline is a hallmark of the malignant phenotype and ChoK over-expression (primarily ChoKβ) has been reported in a variety of human cancers including breast, lung, colorectal and prostate. These observations have recently motivated efforts to develop anti-cancer agents targeting ChoK. Here we summarize our efforts to further validate ChoKα as an oncogenic target by characterizing its tumorigenic potential and exploring the activity of novel small molecule inhibitors. We transduced the ChoKα gene into HEK293 cells to examine the effects of ChoK expression in vitro and in vivo. Under reduced serum conditions, over-expression of ChoK promoted cell growth, increased phospho-ERK and phospho-AKT levels, and reduced p21 levels. ChoKα, but not vector-expressing cells, formed tumors in immune-compromised mice and ChoKα expression levels were positively associated with tumor growth rates. Together, these data suggest that ChoK maintains proliferative pathways in the absence of growth factors, and itself provides an oncogenic driver capable of inducing tumor growth in the absence of other transforming mutations. Recently we identified a novel chemical series that inhibits ChoKα in both enzymatic and cellular assays. The binding of these inhibitors to ChoK protein was confirmed in surface plasmon resonance experiments. A representative member of this lead series, compound A, was characterized in more detail and demonstrated potent enzyme inhibition against ChoKα with an IC50 of 70 nM. Compound A also inhibited the growth of ChoKα -expressing breast cancer lines, MDA-MB-468 and MDA-MB-415, with GI50s of 7 and 2 uM respectively. In contrast, compound A exhibited much lower activity against the non-transformed breast epithelial cell line MCF-12A, with a GI50 >40 uM. Consistent with its effects on cell growth, pCho levels in MDA-MB-415 cells, as measured by NMR, were dose-dependently inhibited up to ∼80% by 24 hours with an IC50 of ∼750 nM. In MDA-MB-415 cells, but not MCF-12A cells, levels of apoptotic markers were increased at 24 hours with compound concentrations β5 uM. In summary, we demonstrated that small molecule inhibition of ChoK results in a dose-dependent decrease of pCho levels, inhibition of proliferation and induction of apoptosis in ChoKα expressing breast cancer cells. We established that exogenous expression of ChoKα in HEK293 cells drives both oncogenic transformation and constitutive activation of proliferative signaling pathways. Taken together, these data further validate ChoKα as a potential therapeutic target in cancer and support the continued investigation into the utility of ChoKα inhibitors as anti-oncogenic agents.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3236. doi:1538-7445.AM2012-3236

Bipiperidinyl carboxylic acid amides as potent, selective, and functionally active CCR4 antagonists

A cell-based assay for the chemokine G-protein-coupled receptor CCR4 was developed, and used to screen a small-molecule compound collection in a multiplex format. A series of bipiperidinyl carboxylic acid amides amenable to parallel chemistry were derived that were potent and selective antagonists of CCR4. One prototype compound was shown to be active in a functional model of chemotaxis, making it a useful chemical tool to explore the role of CCR4 in asthma, allergy, diabetes, and cancer.

Multiplexing G protein-coupled receptors in microarrays: A radioligand-binding assay

Multiplexing of G protein-coupled receptors (GPCRs) in microarrays promises to increase the efficiency, reduce the costs, and improve the quality of high-throughput assays. However, this technology is still nascent and has not yet achieved the status of "high throughput" or laid claim to handling a large set of receptors. In addition, the technology has been demonstrated only when using fluorescent ligands to detect binding, limiting its application to a subset of GPCRs. To expand the impact of multiplexing on this receptor class, we have developed a radiometric approach to the microarray assay. In these studies, we considered two receptors in the alpha-adrenergic receptor family, alpha2A and alpha2C, and the 125I-labeled agonist clonidine. We demonstrate that microarrays of these receptors can be readily detected (signal/noise ratio approximately 160) using a Typhoon 9210 PhosphorImager. In addition, biochemical characterization shows that ligand-binding profiles and selectivity are preserved with the selective antagonists BRL44408 and ARC239. Importantly, these microarrays use approximately 200- to 400-fold less membrane preparation required by conventional assay methods and allow two or more receptors to be assayed in an area equivalent to a standard well of a microtiter plate. The impact of this approach on screening in drug discovery is discussed.

Prevalence of Rickettsia slovaca in Dermacentor marginatus ticks removed from wild boar (Sus scrofa) in northeastern Spain

Rickettsia slovaca, the causative agent of TIBOLA, is transmitted by Dermacentor ticks. Dermacentor marginatus is the most widely species distributed in northeastern Spain, and the wild boar constitutes the main host. D. marginatus ticks were collected from hunter-killed wild boar and were tested by PCR/RFLP. Rickettsial DNA-positive ticks were sequenced using the ompA PCR primers. The prevalence of R. slovaca in D. marginatus ticks was 17.7%. Other spotted fever group rickettsiae were detected in ticks, but these were not definitely identified.

High-index-core Bragg fibers: dispersion properties

We study the group-velocity-dispersion properties of a novel type of Bragg fibers. These new structures are cylindrically symmetric microstructured fibers having a high-index core (silica in our case), like in conventional photonic crystal fibers, surrounded by a multilayered cladding, which is formed by a set of alternating layers of silica and a lower refractive-index dielectric. The combination of the unusual geometric dispersion behavior shown by the multilayered structure and the material dispersion corresponding to the silica core allows us to design nearly constant chromatic dispersion profiles. In this work we focus our attention on flattened dispersion fibers in the 0.8 microm wavelength window and even on ultraflattened dispersion structures about the 1.55 microm point. We include configurations owning positive, negative, and nearly-zero dispersion in both wavelength ranges.

Designing the properties of dispersion-flattened photonic crystal fibers

We present a systematic study of group-velocity-dispersion properties in photonic crystal fibers (PCF's). This analysis includes a thorough description of the dependence of the fiber geometrical dispersion on the structural parameters of a PCF. The interplay between material dispersion and geometrical dispersion allows us to established a well-defined procedure to design specific predetermined dispersion profiles. We focus on flattened, or even ultraflattened, dispersion behaviors both in the telecommunication window (around 1.55 microm) and in the Ti-Za laser wavelength range (around 0.8 microm}. We show the different possibilities of obtaining normal, anomalous, and zero dispersion curves in the above frequency domains and discuss the limits for the existence of the above dispersion profiles.