Episode 6

On 15 December 2017, a simple tweet started a scientific revolution that could change our very understanding of early cancer detection.

Following years of research, X-ZELL used social media to share the first-ever image of a tumour-associated Circulating Endothelial Cell (tCEC) with the public that had been isolated and visualised from a small, 10ml blood sample using a newly developed rare cell detection method.

Leading up to the milestone moment, research carried out at the Institute of Bioengineering and Nanotechnology (IBN) in Singapore had demonstrated that CEC are shed directly from a tumour’s very own blood vessels – thus serving as a highly accurate warning sign of clinically significant disease.

The problem: Despite the cells’ game-changing potential in the fight against one of the most pressing health issues of our time, tCEC proved so hard to find that using them in clinical routine seemed close to impossible.

Enter X-ZELL, which had first demonstrated the ability to find and identify tCEC at a Y Combinator Demo Day in March 2016 and was now – following a year of intense research and clinical trials – ready to make itself known to a global audience.

Having found a way to strip blood samples of healthy cells and visualise the remaining, highly complex tCEC in a routine set-up on standard microscopic slides – a process called liquid biopsy – X-ZELL opened up a new pathway to detecting and treating cancer at the earliest stages, when it can be cured. All by means of a simple, pain-free blood draw.

Less than a year on, X-ZELL’s headline-making tCEC detection technology has now been translated into the company’s first real-life product – X-ZELL Prostate™.

Why prostate cancer?

Prostate cancer is not only one of the most common cancers amongst men worldwide, but also the most controversial.

According to new data by the American Cancer Society, the death toll from prostate cancer has increased 10 per cent year-on-year in 2018 (that’s one death every 18 minutes), but there is still no way to accurately assess whether or not men carry the disease at an early stage.

Even the well-known Prostate-Specific Antigen (PSA) blood test is “hardly more effective than a coin toss”, according to Richard Ablin – the very man who discovered it.

The same is true for the traditional tissue biopsy, a painful and highly invasive process with significant side effects that range from incontinence to impotence. Despite being widely accepted as the ‘gold standard’ for prostate cancer detection, some 75% come back negative, 25% of which are false-negatives, meaning they make it seem like you are healthy, but actually carry the disease.

As a result, a dangerous diagnostic void has formed that is not only responsible for the recent rise in prostate cancer incidence around the world, but also the bewilderment of a whole generation of urologists that are left without a single reliable screening tool (more on the subject here).

How does X-ZELL Prostate™ work?

By scanning small blood samples for tCEC, X-ZELL Prostate™ is able to determine the presence or absence of clinically significant, aggressive prostate cancer in patients with elevated PSA levels (4-10/20 ng/mL) or an abnormal digital rectal examination (DRE) result.

You may think of it as a filter to prevent equivocal screenings results from leading to over-diagnosis and over-treatment.

When used in combination with PSA, X-ZELL Prostate™ can double the Positive Predictive Value (PPV, the probability that aggressive prostate cancer is present) of the standard PSA test while also boosting the Negative Predictive Value (NPV, the probability that aggressive cancer is absent) to over 94 per cent, according to a pilot study carried out in Thailand in 2018.

That way doctors are able to avoid more than 71% of unnecessary biopsies, making X-ZELL’s first liquid biopsy a crucial tool to ensure only those patients take the risk of an intervention that absolutely have to – all by using existing best practice instead of turning the system upside down.

Based on the same principle, X-ZELL Prostate™ may also add value as a tool to reconfirm a negative biopsy and to provide patients with a simple, pain-free alternative during active surveillance.

Why is CEC technology different?

X-ZELL Prostate™ is not the first product on the market trying to support patients with equivocal screening results, but it is the first using tCEC detection technology.

With tCEC deriving directly from the tumour’s chaotically growing blood vessels, they are one of the first types of tumour-derived cells to be shed into the host circulation and thus predestined for early detection.

But there’s more to them: Research into the content of Vascular Endothelial Growth Factor (VEGF) – a signal protein produced by cells that stimulates the formation of blood vessels – has demonstrated that without vascular growth, as indicated by the presence of tCEC, cancer is highly unlikely to cause any harm.

Or as Nava Almog of Tufts University’s School of Medicine put it in 2010, “tumours unable to induce successful angiogenesis remain avascular and microscopic in size.”

As a consequence, experts now hypothesize that the detection of tCEC could not only help us detect cancer early, but also to distinguish between dormant and aggressive disease – a crucial piece of information needed to ensure optimum patient care.

Why don’t you focus on Circulating Tumour Cells (CTC) instead?

According to the University of Twente’s Kiki Andree et al., Circulating Tumour Cells (CTC) are cancer cells that detach from their primary site during the process of cancer metastasis, meaning once they materialise in the blood stream, it may be too late to ensure timely intervention.

As such, the clinical utility of CTC is still controversial, with a Polish research team led by Artur Kowalikpointing out that “despite the fact that nearly 150 years have passed since the first detection and description of CTC in human blood and enormous technological progress that has taken place in this field, especially within the last decade, few CTC detection methods have been approved for routine clinical use.”

As opposed to tCEC, which are blood cells by definition and thus conserved in the host blood, CTC only survive for about 1 to 2.5 hours, as Meng et al.found back in 2004.

With that in mind, CTC prove extremely hard to process and visualise downstream, meaning they only provide a fraction of the information CEC are able to bring to the table.

But why not focus on ctDNA like everyone else?

Most businesses in the liquid biopsy space focus on circulating tumour DNA (ctDNA) to prove the presence or absence of cancer in the blood, and most of them use expensive third party sequencing technology to do so.

Research, however, has yet to prove ctDNA’s efficacy for early cancer detection in clinical routine – especially with view to the inherent risk of producing false-negative and false-positive results and the issue of contamination with DNA from dying blood cells, both of which have been pointed out by Marius Illie et al. in 2014.

The underlying reason is simple maths: If the average cancerous protein undergoes hundreds of modifications while being produced from the original DNA template, and the human genome comprises an estimated 25,000 genes that are responsible for the creation of more than a million proteins, establishing a definite link between ctDNA and the relevant cancerous protein is not always a straightforward process. That’s if you find the relevant DNA fragment in the first place.

The protein itself is not only easier to find, but also avoids a substantial reverse-engineering effort.

The most prominent shortcoming of DNA-based approaches – at least for now – is that they may be affected by ethnicity; meaning current research in the field is limited to a homogenous Caucasian population and has yet to be reciprocated in a more diversified context.

To avoid these shortcomings, X-ZELL has chosen an immunocytopathology-based approach that is unaffected by ethnic variation and capable of retaining information on cell morphology – allowing a cell sample to be identified efficiently as malignant or benign according to stringent cytological criteria.

Why can no one else find tCEC in a routine setting?

Because tCEC carry many common blood cell markers and hardly any specific cancer cell surface markers that would distinguish them from normal blood cells, the consensus has long been that they are simply too hard to find in a routine laboratory – which is also why only a select few scientists have been researching them since they were first described more than 50 years ago.

 X-ZELL cracked the 5CEC code by designing and manufacturing a suite of highly specialised technologies called hMX™ Cell Separation and Cryoimmunostaining™ – both of which are world-unique and exclusive to X-ZELL.

Put simply, step one comprises the separation of cancerous cells from healthy ones based on the principle of negative selection – think of it as removing the haystack as opposed to locating the needle.

Step two is ‘marking’ the remaining cells to determine whether or not 5CEC are present using a procedure called immunofluorescence staining.

While immunofluorescence staining is already fairly common in biological research, X-ZELL has brought it to a new level by performing the process in sub-zero temperatures – which is why X-ZELL’s approach has been patented under the name Cryoimmunostaining™.

What’s more, X-ZELL upped the ante on the number of antibodies it can apply per slide. While normal routine labs are able to apply 2-3 antibodies per slide, X-ZELL found a way to apply up to nine at the same time – enabling it to find much more complex cells and resulting in unprecedented images that aid both diagnosis and patient education.

Covering the entire workflow from cell separation through to cell detection, X-ZELL is capable of detecting a single cancer cell among up to 50 billion blood cells while keeping both cell morphology and RNA intact for downstream analysis – a quality many existing staining methods still lack.

If finding tCEC is so hard, why not use MRI instead?

The role of magnetic resonance imaging (MRI) as a tool to detect and stage clinically significant prostate cancer (csPCa) continues to cause controversy among the medical community.

To cut a long story short, there is indeed growing evidence that MRI may help urologists decide whether or not to perform a painful, invasive biopsy – the same goal X-ZELL is pursuing with X-ZELL Prostate™.

However, most of the research into the topic has been focusing on pre-selected cohorts that had already undergone biopsy and was carried out in centres with extensive experience in the field – meaning robust comparative evidence from randomised controlled trials in less experienced centres is still lacking.

The mere practicality of using MRI as a screening tool has also been subject to intense debate of late, with excessive cost and long waiting times the main concerns among urologists worldwide.

That doesn’t mean MRI doesn’t have a place in early cancer detection, of course. But what it does mean is that MRI and X-ZELL Prostate™ don’t compete in the same arena. Instead, they are highly complementary – with X-ZELL’s solution serving as the perfect indication for MRI and, subsequently, MRI-guided biopsy.

Conversely, X-ZELL Prostate’s™ high Negative Predictive Value (NPV) of 95% would give doctors peace of mind to cut the diagnostic decision-making process short and generate substantial downstream cost savings. 

Is tCEC technology already available on the market? 

From a patient perspective, the most important aspect about X-ZELL’s tCEC detection technology is that the X-ZELL Prostate™ test can be taken at leading Bangkok hospitals – including Bangkok Hospital, Bumungrad Hospital, Samitivej Hospital, Chularat 9 Hospital and Theptarin Hospital – right now.

Using just a small, 10ml blood sample, X-ZELL is not only able determine whether or not tCEC have been located in the blood sample, but also provide your physician with detailed advice on how to proceed – allowing them to make an informed decision which diagnostic steps to take next, if any.

As opposed to many up-and-coming names in the industry, X-ZELL is operating a fully functional and licensed lab in Bangkok that is processing real blood samples every day. A second lab is slated to open in Singapore in Q1’19.

Why tCEC technology is already changing the game

Starting with a simple tweet, it has taken X-ZELL less than year to spread the tCEC message and be invited to speak at some of the largest urology conferences in the world to unravel the cells’ long-standing mystery.

But securing a spot in the history books of medical research and being named one of Asia’s most coveted biotech start-ups was only the first step on a long journey.

The real revolution, the one at the patient’s bedside, is only just beginning: X-ZELL Prostate™ is but the first in a series of liquid biopsies X-ZELL is planning to launch over the coming years. Development on X-ZELL Lung™ and X-ZELL Ovarian™ is already underway, with a series pilot studies about to commence in 2019-20.

An international validation study for X-ZELL Prostate™ is also in the making and about to commence in Singapore in 2019. Once completed, it will allow X-ZELL to revolutionise early cancer detection at a global stage.

One cell at a time.