Circulating Tumor DNA Dynamics Fail to Predict Efficacy of Poly(ADP-ribose) Polymerase/VEGFR Inhibition in Patients With Heavily Pretreated Advanced Solid Tumors.

PURPOSE: Cell-free circulating tumor DNA (ctDNA) has shown its potential as a quantitative biomarker for longitudinal monitoring of response to anticancer therapies. However, ctDNA dynamics have not been studied in patients with heavily pretreated, advanced solid tumors, for whom therapeutic responses can be weak. We investigated whether changes in ctDNA could predict clinical outcomes in such a cohort treated with combined poly(ADP-ribose) polymerase/vascular endothelial growth factor receptor inhibitor therapy. MATERIALS AND METHODS: Patients with metastatic pancreatic ductal adenocarcinoma (PDAC), triple-negative breast cancer (TNBC), small-cell lung cancer (SCLC), or non-small-cell lung cancer (NSCLC) received up to 7 days of cediranib 30 mg orally once daily monotherapy lead-in followed by addition of olaparib 200 mg orally twice daily. Patients had progressed on a median of three previous lines of therapy. Plasma samples were collected before and after cediranib monotherapy lead-in and on combination therapy at 7 days, 28 days, and every 28 days thereafter. ctDNA was quantified from plasma samples using a multigene mutation-based assay. Radiographic assessment was performed every 8 weeks. RESULTS: ctDNA measurements were evaluable in 63 patients. The median baseline ctDNA variant allele fractions (VAFs) were 20%, 28%, 27%, and 34% for PDAC, TNBC, SCLC, and NSCLC, respectively. No association was observed between baseline VAF and radiographic response, progression-free survival, or overall survival (OS). Similarly, no association was found between ctDNA decline and radiographic response or survival. However, an increase in ctDNA at 56 days of combination therapy was associated with disease progression and inferior OS in a landmark analysis. CONCLUSION: ctDNA levels or dynamics did not correlate with radiographic response or survival outcomes in patients with advanced metastatic malignancies treated with olaparib and cediranib.

Cell-free extract based optimization of biomolecular circuits with droplet microfluidics.

Engineering an efficient biomolecular circuit often requires time-consuming iterations of optimization. Cell-free protein expression systems allow rapid testing of biocircuits in vitro, speeding the design-build-test cycle of synthetic biology. In this paper, we combine this with droplet microfluidics to densely scan a transcription-translation biocircuit space. Our system assays millions of parameter combinations per hour, providing a detailed map of function. The ability to comprehensively map biocircuit parameter spaces allows accurate modeling to predict circuit function and identify optimal circuits and conditions.

Lab-on-a-chip technology: impacting non-invasive prenatal diagnostics (NIPD) through miniaturisation.

This paper aims to provide a concise review of non-invasive prenatal diagnostics (NIPD) to the lab-on-a-chip and microfluidics community. Having a market of over one billion dollars to explore and a plethora of applications, NIPD requires greater attention from microfluidics researchers. In this review, a complete overview of conventional diagnostic procedures including invasive as well as non-invasive (fetal cells and cell-free fetal DNA) types are discussed. Special focus is given to reviewing the recent and past microfluidic approaches to NIPD, as well as various commercial entities in NIPD. This review concludes with future challenges and ethical considerations of the field.

Utilizing microfluidics to synthesize polyethylene glycol microbeads for Förster resonance energy transfer based glucose sensing.

Here, we utilize microfluidic droplet technology to generate photopolymerizeable polyethylene glycol (PEG) hydrogel microbeads incorporating a fluorescence-based glucose bioassay. A microfluidic T-junction and multiphase flow of fluorescein isothiocyanate dextran, tetramethyl rhodamine isothiocyanate concanavalin A, and PEG in water were used to generate microdroplets in a continuous stream of hexadecane. The microdroplets were photopolymerized mid-stream with ultraviolet light exposure to form PEG microbeads and were collected at the outlet for further analysis. Devices were prototyped in PDMS and generated highly monodisperse 72 ± 2 µm sized microbeads (measured after transfer into aqueous phase) at a continuous flow rate between 0.04 ml/h-0.06 ml/h. Scanning electron microscopy analysis was conducted to analyze and confirm microbead integrity and surface morphology. Glucose sensing was carried out using a Förster resonance energy transfer (FRET) based assay. A proportional fluorescence intensity increase was measured within a 1-10 mM glucose concentration range. Microfluidically synthesized microbeads encapsulating sensing biomolecules offer a quick and low cost method to generate monodisperse biosensors for a variety of applications including cell cultures systems, tissue engineering, etc.

A 'microfluidic pinball' for on-chip generation of Layer-by-Layer polyelectrolyte microcapsules.

Inspired by the game of "pinball" where rolling metal balls are guided by obstacles, here we describe a novel microfluidic technique which utilizes micropillars in a flow channel to continuously generate, encapsulate and guide Layer-by-Layer (LbL) polyelectrolyte microcapsules. Droplet-based microfluidic techniques were exploited to generate oil droplets which were smoothly guided along a row of micropillars to repeatedly travel through three parallel laminar streams consisting of two polymers and a washing solution. Devices were prototyped in PDMS and generated highly monodisperse and stable 45±2 µm sized polyelectrolyte microcapsules. A total of six layers of hydrogen bonded polyelectrolytes (3 bi-layers) were adsorbed on each droplet within <3 minutes and a fluorescent intensity measurement confirmed polymer film deposition. AFM analysis revealed the thickness of each polymer layer to be approx. 2.8 nm. Our design approach not only provides a faster and more efficient alternative to conventional LbL deposition techniques, but also achieves the highest number of polyelectrolyte multilayers (PEMs) reported thus far using microfluidics. Additionally, with our design, a larger number of PEMs can be deposited without adding any extra operational or interfacial complexities (e.g. syringe pumps) which are a necessity in most other designs. Based on the aforementioned advantages of our device, it may be developed into a great tool for drug encapsulation, or to create capsules for biosensing where deposition of thin nanofilms with controlled interfacial properties is highly required.