Abstract P2-08-02: Interaction of PIK3CA mutation subclasses with response to preoperative treatment with the PI3K inhibitor pictilisib in patients with estrogen receptor-positive breast cancer

Background: Although preclinical data suggest that combining PI3K inhibitors with endocrine therapy may overcome resistance, results from randomized clinical trials have failed to identify a subgroup of patients that derive a substantial benefit. This preoperative window study assessed whether adding the PI3K inhibitor pictilisib can increase the anti-tumor effects of anastrozole in primary breast cancer and aimed to identify the most appropriate patient population for combination therapy.

Methods: In this randomized, open-label, phase 2 study, 167 postmenopausal women with newly diagnosed, operable, ER-positive, HER2-negative breast cancers were recruited. Participants were randomly allocated (2:1, favoring the combination) to two-weeks of preoperative treatment with anastrozole 1 mg once daily or the combination of anastrozole 1mg with pictilisib 260 mg once daily. The primary endpoint was inhibition of tumor cell proliferation, as measured by change in Ki-67 protein expression between tumor samples taken before and at the end of treatment. Secondary endpoints include induction of apoptosis (Caspase3) and safety. Comprehensive biomarkers analyses included targeted NGS of a comprehensive cancer panel of >400 genes (Ampliseq Comprehensive Cancer panel), copy number variation analyses, and pre- and post-treatment reverse-phase protein arrays (RPPA) and RNA profiling (NanoString nCounter platform).

Results:There was significantly greater geometric mean Ki67 suppression of 82.5% (90% CI, 78.3%-85.8%) for the combination vs 70.7% (61.0%-78.0%) for anastrozole [geometric mean ratio (combination/ anastrozole) 0.60 (0.58-0.85);p=0.01]. Higher baseline Ki67, Luminal B status and/or negative PR status were associated with increased benefit from adding pictilisib. A significant interaction was observed between PIK3CA mutation subtypes [helical domain mutations (HD), kinase domain mutations (KD), wildtype (WT)] and mean Ki67 suppression; the combination/anastrozole geometric mean ratio of Ki67 suppression was 0.48 (0.27-0.84; p=0.02) for patients with HD mutations and 0.63 (0.39–1.0; p=0.05) for patients with PIK3Ca WT, compared to 1.17 (0.57–2.41; p=0.64) for patients with KD mutations. This was largely due to patients with HD mutations showing a particularly poor response to anastrozole alone [mean Ki67 suppression 53.9% (9.5%-76.5%)], that was reversed by the addition of pictilisib [mean Ki-67 suppression 78.1% (71.0%-83.4%)]. On the other hand, patients with KD mutations responded well to anastrozole alone [mean Ki-67 suppression 77.7% (57.0%-88.4%)] and showed no benefit from the addition of pictilisib [mean Ki-67 suppression 73.9% (59.8%-83.0%)]. There was no significant difference in induction of apoptosis between treatment groups. Comprehensive pre- and post-treatment biomarkers analyses will be presented.

Conclusions: Adding pictilisib to anastrozole significantly increases the anti-proliferative response to preoperative treatment with anastrozole. A significant interaction was observed between PIK3CA mutation subtypes, with patients with helical domain mutations showing a particularly poor response to anastrozole alone that was reversed by the addition of pictilisib.

Citation Format: Schmid P, Pinder S, Wheatley D, Zummit C, Macaskill EJ, Hu J, Price R, Bundred N, Hadad S, Shia A, Sarker S-J, Lim L, Mousa K, O'Brien C, Wilson TR, Lackner MR, Gendreau S, Gazinska P, Korbie D, Trau M, Mainwaring P, Thompson A, Purushotham A. Interaction of PIK3CA mutation subclasses with response to preoperative treatment with the PI3K inhibitor pictilisib in patients with estrogen receptor-positive breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-02.

Extracellular vesicles as circulating cancer biomarkers: opportunities and challenges

Extracellular vesicles (EVs) are small, lipid-bound particles containing nucleic acid and protein cargo which are excreted from cells under a variety of normal and pathological conditions. EVs have garnered substantial research interest in recent years, due to their potential utility as circulating biomarkers for a variety of diseases, including numerous types of cancer. The following review will discuss the current understanding of the form and function of EVs, their specific role in cancer pathogenesis and their potential for non-invasive disease diagnosis and/or monitoring. This review will also highlight several key issues for this field, including the importance of implementing robust and reproducible sample handling protocols, and the challenge of extracting an EV-specific biomarker signal from a complex biological background.

Re-purposing bridging flocculation for on-site, rapid, qualitative DNA detection in resource-poor settings

Developing molecular diagnostics in resource-poor settings is challenging. As such, we purpose-built a novel bridging flocculation assay for qualitative evaluation of isothermally amplified DNA by naked eye. The flocculation assay was dependent on pH, DNA polymer amounts and lengths. The method was first applied to the rapid and sensitive detection of important plant pathogens and subsequently extended to other pathogens across the animal kingdom to demonstrate the wide applications of our approach.

Abstract P4-05-16: Quality metric study of real-time targeted massive parallel sequencing (MPS) (ampliseq comprehensive cancer panel (CCP)) and bioinformatics in early breast cancer (EBC) using life technologies ion proton system

We undertook a prospective quality assurance and metric study in 26 women with early breast cancer (EBC) in order to identify issues that may interfere with real-time integration of massive parallel sequencing (MPS) with clinical and pathology parameters for clinical decision making.

Pre-operatively, patients underwent formal informed consent process with the aid of bespoke multimedia (iPad) technology to educate patients on a) the logistical aims of the trial b) somatic and hereditary genomics c) privacy and off target (non-cancer) issues.

On Day 1, seven patients (27%) underwent WLE & SNB, 17 (65%) WLE & AXLND, 2 (7%) Mastectomy & SNB.

Samples (tumour and normal) were collected fresh into Qiagen PaxGene Tissue Container preserving both morphology and biomolecules of the sample with lysis of tissues overnight.

Day 2&3; DNA extraction was performed using the Qiagen DSP kit over 1 hour.

DNA MPS CCP was performed on Life technologies Proton P1 chip using in-house modification of manufacturers protocol. The average time taken to run CCP includes 2 days library preparation; 4 hour sequencing run, 8 hours primary analysis for generating read alignments and sequencing files. The Ampliseq protocol required modifications with respect to template input amount and cycling parameters in order to increase the fidelity of library preparation. Limitations in sequencing depth and read qualities with the current technologies lend themselves to approximately 5-6 samples/sequencing run/day if 500x read depth per amplicon is desired.

Days 4-6 manually curated bioinformatics against publicly available mutation databases (e.g. COSMIC, ENSEMBL etc.)

Day 7 communication of results

Molecular Pathology results

The median age was 57, (32-84), 18 (72%) were postmenopausal. Histopathology invasive ductal 22 (84%), invasive lobular 2 (8%) metaplastic 2 (8%).

TNM Staging: T1b 5 (19%), T1c 9 (35%) T2 12 (46%); N0 23 (88%), N1mi 1 (4%), N1a 1 (4%), N2a 1 (4%).

Hormone receptors antibodies: ER (Roche SP1) Strong 20 (77%), Moderate 1 (4%), Weak 1 (4%), Negative 4 (15%); PR (Roche 1E2) Strong 11 (42%), Moderate 10 (38%), Weak 0 (0%), Negative 5 (19%); HER2 IHC (Ventana 4B5) Strong 1 (4%), Moderate 6 (23%), Weak 6 (23%), Negative 13 (50%); HER2 SISH (Ventana inform single probe); 1 SISH positive (mean copy number 29.6); 4 patients (15%) triple negative.

Molecular aberrations identified included oncogenes TP53 2 (8%), PIK3CA 12 (46%) HRAS 2 (8%), AKT1 1 (4%); tumour suppressor genes MLL3 2 (8%), MSH6 1 (4%), ARID1A 1 (4%), and in the germline in tumour suppressor genes EPHB6 1 (4%) and LTK 1 (4%).

Significant technical and bioinformatic challenges were encountered during the development of this metric study including Ampliseq protocol modification and parameter tuning for variant calling algorithm.

In summary, many challenges face the clinical laboratory developing high throughput MPS using desktop MPS. To date this is the first publication of the new Ion Proton P1 chips in development for real-time clinical decision making. Copy-number variation (CNV), RNA-Seq, Methyl-Seq data will be available for presentation at San Antonio.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-05-16.

Use of tunable nanopore blockade rates to investigate colloidal dispersions

Tunable nanopores fabricated in elastomeric membranes have been used to study the dependence of ionic current blockade rate on the concentration and electrophoretic mobility of particles in aqueous suspensions. A range of nanoparticle sizes, materials and surface functionalities has been tested. Using pressure-driven flow through a pore, the blockade rate for 100 nm carboxylated polystyrene particles was found to be linearly proportional to both transmembrane pressure (between 0 and 1.8 kPa) and particle concentration (between 7 × 10(8) and 4.5 × 10(10) ml( - 1)). This result can be accurately modelled using Nernst-Planck transport theory, enabling measurement of particle concentrations. Using only an applied potential across a pore, the blockade rates for carboxylic acid and amine coated 500 and 200 nm silica particles were found to correspond to changes in their mobility as a function of the solution pH. Scanning electron microscopy and confocal microscopy have been used to visualize changes in the tunable nanopore geometry in three dimensions as a function of applied mechanical strain. The pores were conical in shape, and changes in pore size were consistent with ionic current measurements. A zone of inelastic deformation adjacent to the pore has been identified as important in the tuning process.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) composite biomaterials for bone tissue regeneration: in vitro performance assessed by osteoblast proliferation, osteoclast adhesion and resorption, and macrophage proinflammatory response

The efficacy of composite materials for bone tissue engineering is dependent on the materials' ability to support bone regeneration whilst inducing a minimal inflammatory response. In this study we examined the in vitro osteogenic and inflammatory properties of poly(3-hydroxybutyrate-co-3-valerate) (PHBV) with various calcium phosphate-reinforcing phases: nano-sized hydroxyapatite (HA); submicron-sized calcined hydroxyapatite (cHA); and submicron-sized beta-tricalcium phosphate (beta-TCP), using bioassays of cultured osteoblasts, osteoclasts, and macrophages. Our study showed that the addition of a nano-sized reinforcing phase to PHBV, whilst improving osteogenic properties, also reduces the proinflammatory response. Proinflammatory responses of RAW264.7/ELAM-eGFP macrophages to PHBV were shown to be markedly reduced by the introduction of a reinforcing phase, with HA/PHBV composites having the lowest inflammatory response. Osteoclasts, whilst able to attach to all the materials, failed to form functional actin rings or resorption pits on any of the materials under investigation. Cultures of osteoblasts (MC3T3-E1) readily attached and mineralised on all the materials, with HA/PHBV inducing the highest levels of mineralization. The improved biological performance of HA/PHBV composites when compared with cHA/PHBV and beta-TCP/PHBV composites is most likely a result of the nano-sized reinforcing phase of HA/PHBV and the greater surface presentation of mineral in these composites. Our results provide a new strategy for improving the suitability of PHBV-based materials for bone tissue regeneration.

Emulsion strategies in the microencapsulation of cells: Pathways to thin coherent membranes

Microencapsulation of cell spheroids in an immunoselective, highly biocompatible, biomembrane offers a way to create viable implantation options in the treatment of insulin-dependent diabetes mellitus (IDDM). Traditionally the encapsulation process has been achieved through the injection/extrusion of alginate/cell mixtures into a calcium chloride solution to produce calcium alginate capsules around the cells. A novel alternative is explored here through a procedure using an emulsion process to produce thin adherent calcium alginate membranes around cell spheroids. In this study, a thorough investigation has been used to establish the emulsion process parameters that are critical to the formation of a coherent alginate coat both on a model spheroid system and subsequently on cell spheroids. Optical and fluorescence microscopy are used to assess the morphology and coherence of the calcium alginate/poly-L-ornithine/alginate (APA) capsules produced.

Postsynthesis stabilization of free-standing mesoporous silica films

Mixed ammonia-water vapor postsynthesis treatment provides a simple and convenient method for stabilizing mesostructured silica films. X-ray diffraction, transmission electron microscopy, nitrogen adsorption/desorption, and solid-state NMR (13C, 29Si) were applied to study the effects of mixed ammonia-water vapor at 90 degrees C on the mesostructure of the films. An increased cross-linking of the silica network was observed. Subsequent calcination of the silica films was seen to cause a bimodal pore-size distribution, with an accompanying increase in the volume and surface area ratios of the primary (d = 3 nm) to secondary (d = 5-30 nm) pores. Additionally, mixed ammonia-water treatment was observed to cause a narrowing of the primary pore-size distribution. These findings have implications for thin film based applications and devices, such as sensors, membranes, or surfaces for heterogeneous catalysis.

Biomimetic Pathways for Assembling Inorganic Thin Films

Living organisms construct various forms of laminated nanocomposites through directed nucleation and growth of inorganics at self-assembled organic templates at temperatures below 100°C and in aqueous solutions. Recent research has focused on the use of functionalized organic surfaces to form continuous thin films of single-phase ceramics. Continuous thin films of mesostructured silicates have also been formed on hydrophobic and hydrophilic surfaces through a two-step mechanism. First, under acidic conditions, surfactant micellar structures are self-assembled at the solid/liquid interface, and second, inorganic precursors condense to form an inorganic-organic nanocomposite. Epitaxial coordination of adsorbed surfactant tubules is observed on mica and graphite substrates, whereas a random arrangement is observed on amorphous silica. The ability to process ceramic-organic nanocomposite films by these methods provides new technological opportunities.

Field-Induced Layering of Colloidal Crystals

An electrohydrodynamic methodology has been developed that makes possible the precise assembly of two- and three-dimensional colloidal crystals on electrode surfaces. Electrophoretically deposited colloidal particles were observed to move toward one another over very large distances (greater than five particle diameters) to form two-dimensional colloidal crystals for both micrometer- and nanometer-size particles. This coalescence of particles with the same charge is opposite to what is expected from electrostatic considerations and appears to result from electrohydrodynamic fluid flow arising from an ionic current flowing through the solution. The ability to modulate this "lateral attraction" between particles, by adjusting field strength or frequency, facilitates the reversible formation of two-dimensional fluid and crystalline colloidal states on the electrode surface. Further manipulation allows controlled structures to be assembled.

Fellowship programs in critical care medicine: 1990/1991

Studies have demonstrated that polymeric biomaterials have the potential to support osteoblast growth and development for bone tissue repair. Poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate) (PHBV), a bioabsorbable, biocompatible polyhydroxy acid polymer, is an excellent candidate that, as yet, has not been extensively investigated for this purpose. As such, we examined the attachment characteristics, self-renewal capacity, and osteogenic potential of osteoblast-like cells (MC3T3-E1 S14) when cultured on PHBV films compared with tissue culture polystyrene (TCP). Cells were assayed over 2 weeks and examined for changes in morphology, attachment, number and proliferation status, alkaline phosphatase (ALP) activity, calcium accumulation, nodule formation, and the expression of osteogenic genes. We found that these spindle-shaped MC3T3-E1 S14 cells made cell-cell and cell-substrate contact. Time-dependent cell attachment was shown to be accelerated on PHBV compared with collagen and laminin, but delayed compared with TCP and fibronectin. Cell number and the expression of ALP, osteopontin, and pro-collagen alpha1(I) mRNA were comparable for cells grown on PHBV and TCP, with all these markers increasing over time. This demonstrates the ability of PHBV to support osteoblast cell function. However, a lag was observed for cells on PHBV in comparison with those on TCP for proliferation, ALP activity, and cbfa-1 mRNA expression. In addition, we observed a reduction in total calcium accumulation, nodule formation, and osteocalcin mRNA expression. It is possible that this cellular response is a consequence of the contrasting surface properties of PHBV and TCP. The PHBV substrate used was rougher and more hydrophobic than TCP. Although further substrate analysis is required, we conclude that this polymer is a suitable candidate for the continued development as a biomaterial for bone tissue engineering.

The Entry of Free Radicals Into Polystyrene Latex Particles

Mechanistic understanding of the processes governing the kinetics of emulsion polymerization has both scientific and technical interest. One component of this process that is poorly understood at present is that of free radical entry into latex particles. Measurements were made of the entry rate coefficient as a function of temperature for free radicals entering polystyrene latex particles in seeded emulsion polymerizations initiated by γ-rays. The activation energy for entry was found to be less than 24�3 kJ mol-1, consistent with entry being controlled by a physical (e.g., diffusional ) rather than a chemical process. Measurement of the entry rate coefficient as a function of the γ-ray dose rate suggested that the factors that determine the entry rate when the primary free radicals are uncharged are similar to those that determine the entry rate for charged free radicals derived from chemical initiation by peroxydisulfate. This result was consistent with measurements of the entry rate coefficient of charged free radicals derived from peroxydisulfate; these data were found to be virtually independent of both the extent of the latex surface coverage by the anionic surfactant sodium dodecyl sulfate and the ionic strength of the continuous phase. The data refute several proposals given in the literature for the rate-determining step for entry, being inconsistent with control by (1) collision of free radicals with the latex particles, (2) surfactant desorption , and (3) an electrostatic barrier arising from the colloidal nature of the entering free radical. The origin of the activation energy for entry remains obscure.