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Apostle MiniMax Technology

The ability to isolate and analyze circulating cell free DNA (cfDNA) at very low concentrations is becoming increasingly important, particularly in non-invasive prenatal test (NIPT), early cancer detection, and infectious disease diagnosis. Highly efficient isolation of cfDNA from complexed biological medium is a crucial step for subsequent cfDNA analysis. 

Apostle MiniMaxTM technology offers a best-in-class efficiency and purity compared with conventional technologies to capture and isolate the circulating cell-free genetic materials.

APPLICATIONS

  • Apostle MiniMax technology has been applied in world-class research and development projects of novel liquid biopsy technologies.  Some examples include: 

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  • Efficient detection and post-surgical monitoring of colon cancer with a multi-marker DNA methylation liquid biopsy. Jin et al. PNAS February 2, 2021 118 (5) e2017421118; https://doi.org/10.1073/pnas.2017421118 

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  • Multiplex assays, involving the simultaneous use of multiple circulating tumor DNA (ctDNA) markers, can improve the performance of liquid biopsies so that they are highly predictive of cancer recurrence. We have developed a single-tube methylation-specific quantitative PCR assay (mqMSP) that uses 10 different methylation markers and is capable of quantitative analysis of plasma samples with as little as 0.05% tumor DNA. In a cohort of 179 plasma samples from colorectal cancer (CRC) patients, adenoma patients, and healthy controls, the sensitivity and specificity of the mqMSP assay were 84.9% and 83.3%, respectively. In a head-to-head comparative study, the mqMSP assay also performed better for detecting early-stage (stage I and II) and premalignant polyps than a published SEPT9 assay. In an independent longitudinal cohort of 182 plasma samples (preoperative, postoperative, and follow-up) from 82 CRC patients, the mqMSP assay detected ctDNA in 73 (89.0%) of the preoperative plasma samples. Postoperative detection of ctDNA (within 2 wk of surgery) identified 11 of the 20 recurrence patients and was associated with poorer recurrence-free survival (hazard ratio, 4.20; P = 0.0005). With subsequent longitudinal monitoring, 14 patients (70%) had detectable ctDNA before recurrence, with a median lead time of 8.0 mo earlier than seen with radiologic imaging. The mqMSP assay is cost-effective and easily implementable for routine clinical monitoring of CRC recurrence, which can lead to better patient management after surgery. 

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  • We developed a computational program whereby available SD regions can be processed and analyzed efficiently for their potential use as biomarkers of the aneuploidy of interest. For the five common aneuploidies, i.e., trisomy 13, 18, 21, and two sex chromosome aneuploidies, a total of 21,772 candidate SD biomarker sequences together with their corresponding primer/probe sets were generated. The primer/probe sets were tested using a real-time PCR-based multicolour melting curve analysis for simultaneous detection of the five common aneuploidies, and yielded 100% clinical sensitivity and 99.64% specificity when subjected to a clinical evaluation. Following the observations that the SD biomarkers for aneuploidy could be better detected by digital PCR with improved accuracy, we established a noninvasive prenatal testing protocol for trisomy 21 and attained 100% concordance with next generation sequencing.

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  • Our study confirmed that SD regions are preferred biomarkers for aneuploidy detection and in particular SD-based digital PCR could find potential use for NIPT of trisomy. A similar strategy can be applied to other chromosomal abnormality and genetic disorders.

UNIQUENESS

Apostle MiniMax technology ensures precise capture and separation of circulating genetic materials for liquid biopsy analysis. This is achieved through Apostle’s novel proprietary MiniMax magnetic nanoparticles (Exhibit 2-8) with innovative features:

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  • Novel material composition and surface chemistry - completely distinct from the conventional paramagnetic or superparamagnetic technologies

  • Exceptionally large surface area

  • Minimized variation

  • Best-in-class suspension property

  • Superb magnetic power

  • Superb resistance to particle clustering

SIGNIFICANCE

A recent paper published in JAMA Oncology by Torga & Pienta revealed that, strikingly, 2 major commercial liquid biopsy tests show significant and clinically unacceptable discordance. 

Why do liquid biopsy tests differ so significantly? Are they reliable? 

Among other impact factors, the extraction method of circulating free DNA (cfDNA) plays a major role here. Data show that different cfDNA extraction methods yield significantly different amounts of cfDNA by 10% to 10 folds, and consequently result in discordant conclusions. When we study genomic DNA isolated from the nucleus of cells, this level of difference may not matter much – because the amount of genetic material commonly reaches hundreds of micrograms (ug), so the downstream testing methods have enough genetic material to work with anyway. However, when we study cfDNA, this level of difference may result in a fundamental discordance, because the amount of cfDNA is commonly less than 100 nanograms (ng). Slight difference of cfDNA yields may result in critical impact on the testable copies of cancer mutations and the signal-to-noise ratio. 

We illustrate how the accuracy of a liquid biopsy is impacted by the cfDNA sample preparation in a figure below. To have a reliable liquid biopsy testing, a highly efficient cfDNA extraction must be achieved.

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