thank Wealth. I like how you ROLL brother. see you in the 20's.
HI Wealth, You could be right. very impressed with their traction getting insurance companies. be nice to see blue cross drop for them. hoping TROV gets the same reception. good luck with BIOC. I think you will do well.
I did a lot of DD on BIOC over last weekend. My conclusion was that even though its1st to market with a CTC and from my understanding a cTdna test via blood its lacks the industry visibility and credibility needed to sustain a substantial slice of the market. Albeit , they will get some traction and continue to show huge REV growth as they did last Q. Yet once MYGN gets into the space ( blood ) via CTC they will dominate the space as they have over 900 ( approx. ) insurance underwriter relationships and hundreds of thousands of Doc relationships. BIOC recently made some very SR MGMT changes as I believe they realized they missed the pre roll out credibility piece. Which is what TROV is focused on. Docs need to be convinced via data and crowd sourcing versus slick PowerPoints. with all the being said ,I still liked BIOC for a small trade yet my concern then turned to their balance sheet which tells me they will raise soon. thereafter, it might be worth a small trade for me, which could be confirmed with Q1 results. nevertheless, that's my humble opinion. I now await to be slandered by everyone ! PS: I don't think you can get that hurt making a bet on BIOC down here. I just happen to believe TROV is the right horse to place my bet on in this emerging space. fingers crossed.
tight trading range until next catalyst. Which should be around the corner. Expecting data set back from clinical beta roll-out and insurance coverage update. patience will be rewarded here in my humble opinion.
As a patient i would want to know asap so i could try something else. Its a terrible situation yet knowledge is power and in the case if cancer time !!! Time is everything in critical care.
Not sure of source. Found in good awhile back. Should be easy to locate. Glad u found it informative. Knowledge is power when investing in bio space.
look at Volume is that showing your conviction ? its all about volume.. typically this dip would have been met with huge buying . thus, the sentiment is negative. on a macro bio sentiment and especially in the sub sector of diagnostics. read the tape not the tea leaves. i'm stuck in this position now. hoping we get some good news !! soon.........
ED you should not that this board might control .000001% of float. nothing written here can move a stock on iota either way..
just look at the other diagnostic companies. their is no real buying. other then ILMN which is a beast. that tells me longs are giving up. when you see a huge sell off being met with 3 x normal buy side volume that indicates enthusiasm. just saying .. been trading for over 20 yrs. you can check me out at tracking the insiders dotcom. that's me in vid.
Why do you engage with such hostility. the retail sentiment is very low across the BIO space and especially in the diagnostic space. from my reading on the LION and TWITS it seems like longs are giving up. I believe this to be a contrarian indicator. neverhtess, this is my perspective. its ok not to agree yet to attack an opposing view is unnecessary. put me on ignore and have a blessed life. all good brother. I'm just a surfer in cabo , trading full time .nothing but good vibes for you and everyone. I write on the boards as I have time between trades. TROV is mid term position for me.
I stand by everything I share ! I believe character counts and that god is watching every move. I don't think there is anything wrong with bringing god into a financial discussion as Pepsi once stated as I believe everything is under his domain.
I did as I'm uncomfortable when you berate me for sharing my learnings or sentiment as my family follows. We should all be able to share without being attacked. Please ignore my posts thus eliminate your need to attack me. god bless and thanks
In 2012, Charles Swanton was forced to confront one of cancer's dirtiest tricks. When he and his team at the Cancer Research UK London Research Institute sequenced DNA from a handful of kidney tumours, they expected to find a lot of different mutations, but the breadth of genetic diversity within even a single tumour shocked them. Cells from one end differed from those at the other and only one-third of the mutations were shared throughout the whole mass. Secondary tumours that had spread and taken root elsewhere in the patients' bodies were different again1.
The results confirmed that the standard prognostic procedure for cancer, the tissue biopsy, is woefully inadequate — like trying to gauge a nation's behaviour by surveying a single street. A biopsy could miss mutations just centimetres away that might radically change a person's chances for survival. And although biopsies can provide data about specific mutations that might make a tumour vulnerable to targeted therapies, that information is static and bound to become inaccurate as the cancer evolves.
Swanton and his team laid bare a diversity that seemed insurmountable. “I am still quite depressed about it, if I'm honest,” he says. “And if we had higher-resolution assays, the complexity would be far worse.”
But researchers have found ways to get a richer view of a patient's cancer, and even track it over time. When cancer cells rupture and die, they release their contents, including circulating tumour DNA (ctDNA): genome fragments that float freely through the bloodstream. Debris from normal cells is normally mopped up and destroyed by 'cleaning cells' such as macrophages, but tumours are so large and their cells multiply so quickly that the cleaners cannot cope completely.
By developing and refining techniques for measuring and sequencing tumour DNA in the bloodstream, scientists are turning vials of blood into 'liquid biopsies' — portraits of a cancer that are much more comprehensive than the keyhole peeps that conventional biopsies provide. Taken over time, such blood samples would show clinicians whether treatments are working and whether tumours are evolving resistance.
As ever, there are caveats. Levels of ctDNA vary a lot from person to person and can be hard to detect, especially for small tumours in their early stages. And most studies so far have dealt with only handfuls or dozens of patients, with just a few types of cancer. Although the results are promising, they must be validated in larger studies before it will be clear whether ctDNA truly offers an accurate view — and, more importantly, whether it can save or improve lives. “Just monitoring your tumour isn't good enough,” says Luis Diaz, an oncologist at Johns Hopkins University in Baltimore, Maryland. “The challenge that we face is finding true utility.”
If researchers can clear those hurdles, liquid biopsies could help clinicians to make better choices for treatment and to adjust those decisions as conditions change, says Victor Velculescu, a genetic oncologist at Johns Hopkins. Moreover, the work might provide new therapeutic targets. “It will help bring personalized medicine to reality,” says Velculescu. “It's a game-changer.”
Scientists first reported finding DNA circulating in human blood in 1948 (ref. 2), and specifically in the blood of people with cancer in 1977 (ref. 3). It took another 17 years to show that this DNA bore mutations that are hallmarks of cancer — proof that it originated from the tumours4, 5.
The first practical use of circulating DNA came in another field. Dennis Lo, a chemical pathologist now at the Chinese University of Hong Kong, reasoned that if tumours could flood the blood with DNA, surely fetuses could, too. In 1997, he successfully showed that pregnant women carrying male babies had fetal Y chromosomes in their blood6. That discovery allowed doctors to check a baby's sex early in gestation without disturbing the fetus, and ultimately to screen for developmental disorders such as Down's syndrome without resorting to invasive testing. It has revolutionized the field of prenatal diagnostics (see Nature 507, 19; 2014).
“Cancer has been slower to catch on,” says Nitzan Rosenfeld, a genomicist at the Cancer Research UK Cambridge Institute. This is partly because tumour DNA is much harder to detect than fetal DNA. There is typically less of it in the blood, and the amounts are extremely variable. In people with very advanced cancers, tumours might be the source of most of the circulating DNA in the blood, but more commonly, ctDNA makes up barely 1% of the total and possibly as little as 0.01%. Early sequencing technologies were not up to the task of detecting it — at least, not consistently or reliably enough to use ctDNA as a biomarker.
“It'll help us answer questions in oncology That have never been answered before.”
But the past decade has brought sensitive techniques that can detect and quantify minute amounts of DNA. For example, an amplification method known as BEAMing — which fastens circulating DNA to magnetic beads that can then be isolated and counted — can detect ctDNA even if it is outnumbered by healthy cell DNA by a factor of 10,000 to 1.
Genetic oncologists Bert Vogelstein and Kenneth Kinzler at Johns Hopkins developed the technique, and in 2007 they described7 using it to track ctDNA in 18 people who were being treated for bowel cancer. After surgery, the patients' ctDNA levels fell by 99%, but in many cases the signal did not disappear completely. In all but one of the people with detectable ctDNA at the first follow-up appointment, the tumours eventually returned. None of the people with undetectable levels after surgery experienced a recurrence.
These results suggested that ctDNA can reveal how well a patient has responded to surgery and whether they need chemotherapy to finish off any lingering cancer cells. Researchers soon found similar results for other types of cancer. Rosenfeld and his Cancer Research UK colleagues James Brenton and Carlos Caldas showed that ctDNA provides a precise portrait of advanced ovarian and breast cancers8. And in the largest study yet, Diaz and other members of the Johns Hopkins group detected ctDNA in at least 75% of patients with advanced tumours, in organs as diverse as the pancreas, bladder, skin, stomach, oesophagus, liver and head and neck9. (Brain cancers were a notable exception, because the blood–brain barrier stops tumour DNA from reaching the bloodstream.)
Circulating DNA might perform better than the protein biomarkers that researchers have been seeking and refining for decades. Proteins are used in the clinic to diagnose illnesses and monitor people undergoing treatment. For example, prostate-specific antigen is a biomarker for prostate cancer, but it can give false positives because there are other reasons that the antigen can be elevated in the blood. False positives should be rarer with ctDNA because it is defined by mutations and other genomic changes that are hallmarks of cancer cells. And although most protein biomarkers stay in the blood for weeks, ctDNA has a half-life of less than two hours, so it gives a clearer view of a tumour's present, rather than its past. The Cambridge and Johns Hopkins teams have found that ctDNA is more sensitive than protein biomarkers when it comes to detecting breast10 and bowel9 cancers, respectively, and it is more accurate at tracking tumour disappearance, spread and recurrence.
Illustration by Oliver Munday
Both teams also showed that ctDNA was more sensitive than circulating tumour cells — intact cancer cells that also travel around the bloodstream and have been an intense area of research. In a sub-study of 16 people, Diaz's team found that where both were present, ctDNA fragments outnumbered circulating tumour cells by 50 to 1 (ref. 9). And although ctDNA was always there if the circulating cells were, 13 people with detectable tumour DNA had no trace of such cells.
But most exciting to scientists, says Diaz, is the ability to watch tumours evolve and adapt over time: “It'll help us answer questions in oncology that have never been answered before.”
For example, why do so many targeted therapies eventually fail? Gefitinib and panitumumab are among several drugs that block the epidermal growth factor receptor (EGFR), a protein involved in cell growth and division that is overactive in a number of cancers. People taking these drugs do very well — briefly. But after a few months, their cancers almost always develop resistance, often through changes to other genes, such as KRAS, which is mutated in many cancers.
To monitor patients and decide on the next course of action, clinicians would normally need to take multiple biopsies. But people with advanced cancer often have several tumours to test, and different parts of any single tumour could be resistant in different ways. Biopsies are invasive and risky, and difficult for inaccessible and fragile organs such as the lungs. “You can't just go to the patient and get five more biopsies after the treatment fails,” says Velculescu. Taking blood is simple in comparison.
In 2012, Diaz's team reported11 using ctDNA to study patients who were being treated with EGFR inhibitors. The researchers found 42 different KRAS mutations that confer resistance; on average, these turned up 5 months before imaging techniques showed that the tumours were progressing. The team was specifically looking for KRAS mutations, but Rosenfeld's group has used ctDNA to identify resistance mutations from a blind start. Last year, the researchers described how they had sequenced the complete exomes — the 1% of the genome that encodes protein — in blood samples from six people being treated for advanced breast, lung or ovarian cancers. In five cases, the unguided search revealed routes to resistance, such as mutations that prevent drugs from binding to their target proteins12.
Spotting resistance early would let clinicians take patients off toxic and expensive drugs that are unlikely to keep working. And by identifying the mutations that underlie the resistance, they could find effective alternatives or drug combinations. “The hope is that we can turn cancer from a deadly disease into a chronic one,” says Velculescu. “You treat someone with one therapy and when it stops working, you switch, or alternate back and forth.”
Despite its promise, ctDNA is not yet ready for a starring role in the clinic. For one thing, the most sensitive techniques for detecting it, such as BEAMing, rely on some knowledge of which mutations to look for. This knowledge can be provided by taking a biopsy, sequencing its mutations, designing patient-specific molecular probes that target them, and using those probes to analyse later blood samples — a laborious approach that must be repeated for each patient. The alternative is to use exome sequencing, as Rosenfeld's team did. This requires no previous knowledge about the cancer, but it is prohibitively expensive to sequence and analyse every sample at the depth required to detect rare mutant fragments.
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Maximilian Diehn, a radiation oncologist at Stanford University in California, has tried to combine the best of both worlds. His team identified a small proportion of the genome — just 0.004% — that is repeatedly mutated in lung cancers13. Whenever the researchers get a new blood sample, they sequence this fraction 10,000 times over. This picks up even rare mutant fragments, and the focused approach keeps costs down. Because almost everyone with lung cancer has at least one mutation in these regions, the method should work in almost every patient, says Diehn. The team is now working to develop similar mutation panels for other types of cancer, and to validate the technique in clinical trials — work that could take several years.
Like practically all ctDNA biopsy techniques, Diehn's approach does not do well at picking up early forms of cancer. In a small study13, it detected every lung cancer of stage II or higher, but only half of stage I tumours. This is understandable — advanced cancers simply discharge more DNA — but it limits ctDNA's potential as a cancer-screening tool.
Diehn says that more-sensitive techniques could overcome this problem, but Diaz disagrees. “The limiting factor is biology,” he says. “There just aren't a lot of fragments in circulation.” And if ctDNA hints at the presence of an undetected cancer, what then? “If you detect a mutation in the circulation, you don't know where it's coming from,” says Diaz.
There are other unknowns, too. Does ctDNA paint a truly representative portrait of a cancer? Do tumours that have spread to other organs release as much DNA as the original tumours? Do all the cells in a tumour release as much ctDNA as each other? Diaz says that the only way to answer these questions is to do 'warm autopsies' — to take samples and characterize all of a person's tumours very soon after death, and compare them with ctDNA extracted in life. “This is the heavy lifting that'll need to be done in the field,” he says.
And the biggest question remains: does an accurate picture of tumour burden, or a real-time look at emerging mutations, actually save patients or improve their quality of life? Even if doctors discover that someone's tumour has developed a resistance mutation, that insight is useless if there are no drugs that target the mutation. “The limitation is the reality of targeted therapies,” says Velculescu. “You get all this information — but so what? Our approaches to understanding cancer are outstripping our clinical options.”
Even if ctDNA does not yet affect outcomes, scientists say that it is an invaluable research tool, and clinicians are starting to collect it routinely. Swanton, for example, is leading a £14-million (US$24-million) lung-cancer study called TRACERx (Tracking Cancer Evolution Through Therapy), which will use both conventional biopsies and ctDNA collected once every three months. The circulating DNA may or may not provide clues that help the study participants, but at the very least, it will give Swanton a much better understanding of how lung cancer evolves, and how to control that evolution.
As Rosenfeld argues, it is better to have this information than not to. Currently, he says, “we're groping in the dark. Why would you do that if you have a tool that allows you to see what's happening?”
Advances in Gene Sequencing Led to Clinically Useful ctDNA Tests
A major factor in the surging interest in ctDNA has been the rapid drop in cost for analyzing genetic information. In a development that puts Moore's Law to shame, costs for whole genome sequencing dropped from $1 billion for the first complete genome sequenced by the Human Genome Project to $350,000 per genome in 2008 and more recently to about $1,000 for a genome sequenced with Illumina's commercially available HiSeq X Ten sequencing system.
Cancer researchers have been challenged by the problems of how to discriminate ctDNA from normal cell-free DNA, to detect extremely low levels of ctDNA, and to count accurately the number of mutant ctDNA fragments in a blood sample. The sensitivity of polymerase chain reaction (PCR)-based digital approaches improved with the addition of NGS, in which DNA is fragmented into small segments that can be quickly sequenced in millions of parallel reactions known as "reads" and then reassembled so that the set of reads shows the entire DNA sequence.
The half-life of ctDNA is about two hours, and changes in ctDNA levels can be apparent days to weeks before changes in imaging or in protein biomarkers. Because ctDNA is specific for the individual patient's tumor, it is likely to avoid some of the false-positive problems associated with other cancer biomarkers.
Detecting Cancer and Monitoring Cancer Stages Without Biopsy
Most ctDNA strands contain between 180 and 200 base pairs, similar to the 180 base-pair multiples characteristic of apoptosis, and are thought to result mainly from passive release into the blood of ctDNA after cell death.
The presence of ctDNA after resection (but before adjuvant chemotherapy) indicates residual disease. Absence of ctDNA might identify a patient subgroup at low risk for recurrence who could be spared the risk, expense, and discomfort of adjuvant therapy. In 2008, a team of Johns Hopkins researchers reported that mutation-specific probes for 18 subjects undergoing multimodality therapy for colorectal cancer and monitored for two to five years showed that "ctDNA measurements could be used to reliably monitor the tumor dynamics in subjects with cancer who were undergoing surgery or chemotherapy."
The authors suggested that ctDNA levels reflect the total systemic tumor burden because they decreased after complete resection and increased as new radiologically-apparent lesions developed. The researchers also pointed out that micrometastatic lesions (smaller than a few millimeters) contribute to tumor burden and to ctDNA levels although they are not detectable by imaging.
"For a melanoma patient who is free of disease after surgery but at risk for recurrence, ctDNA could be a nice way to follow without having to do frequent CT scans," Dr Chapman said. It is also expected to be useful in situations in which tissue biopsy is undesirable or cannot be done.
However, an important unanswered question is how often these tests should be done. "We need to know how meaningful small changes in the ctDNA level are — sensitivity, specificity, and lead-time bias," he said.
Monitoring Tumor Burden, Response to Therapy, and Resistance
"Another key advantage is that ctDNA could overcome the issue of tumor heterogeneity," commented Dr Park. "Different sites of disease often have different mutational profiles. Since blood, and therefore ctDNA, acts as a 'reservoir' for all sites of disease, ctDNA is representative for all sites of metastases."
A research team from Dr Chapman's lab led by Parisa Momtaz, MD, reported at this year's American Society of Clinical Oncology (ASCO) Annual Meeting that in melanoma patients with BRAF-v600E mutations, ctDNA correlated well with tumor burden measured by radiographic imaging.
"The ASCO cohort of 11 patients was to convince ourselves that we could get the assay to work (proof-of-principle) and that it correlated with what was clinically going on," Dr Chapman said. "We have now studied ctDNA in about 60 patients. We are focusing on patients treated with immunotherapy because radiographic evaluation of these responses are somewhat equivocal. We hope that ctDNA will add more clarity and tell us whether the immune system is attacking the tumor or not."
Also at ASCO, Nicholas C. Turner, MD, consultant medical oncologist at the Institute of Cancer Research, London, United Kingdom, and colleagues reported that in primary breast cancer tumor-specific ctDNA levels can predict early relapse.
ctDNA might also provide early warning that the patient has developed treatment-resistant disease. Sarah B. Goldberg, MD, MPH, assistant professor of medicine at Yale University School of Medicine, New Haven, Connecticut, and colleagues reported that ctDNA could be used to detect both sensitizing and resistance EGFR mutations in patients with advanced lung cancer treated with EGFR tyrosine kinase inhibitors. The researchers suggested that using NGS to detect sensitizing and resistance mutations in plasma ctDNA might allow earlier identification of resistance in patients treated with targeted therapies.
Similarly, a team of researchers from nine cancer centers in Italy found that KRAS mutations in ctDNA could be detected in over 35% of patients with non–small-cell lung cancer who became resistant to tyrosine kinase inhibitors.
In discussing this research, Luis A. Diaz Jr, MD, from the Ludwig Center for Cancer Genetics and Therapeutics at Johns Hopkins University School of Medicine in Baltimore, and Alberto Bardelli, PhD, from the Laboratory of Molecular Genetics, Institute for Cancer Research and Treatment, University of Torino, Italy, wrote, "This understanding of the mechanisms of acquired resistance to targeted agents at the molecular level can be used to plan combinatorial treatments with drugs that will suppress the expansion of the clones that are responsible for most of the current failures of medical treatment. This knowledge could result in the early adoption of alternate therapies before clinical resistance is detected."
Dr Chapman said, "I have this fantasy that you might use this to screen chemotherapy drugs in a patient. You could give them one dose of drug, then measure their ctDNA response. If there is no tumor death, the ctDNA levels wouldn't change."
ctDNA: From Bench to Bedside
Currently, monitoring genetic changes in a tumor requires multiple biopsies. "In the future, it might just be a matter of drawing a tube of blood," Dr Chapman said.
However, Dr Park warned that there has yet been little to no validation of ctDNA testing and that published studies show considerable variability due partly to lack of quality control and uniform standards.
"How the plasma is prepared makes a huge difference, which isn't always appreciated. How the ctDNA is analyzed is also quite variable among studies, with some technologies being better suited for specific applications. So for now, we would counsel clinicians not to jump the gun on this. We have to be extremely thoughtful and careful when dealing with ctDNA and its applications," Dr Park commented. He quoted another researcher (Dan Hayes, MD, from the University of Michigan), who says it best: "A bad test can be just as bad as a bad drug."
"Therefore I believe we need to apply the same rigorous standards of testing drugs to the development of ctDNA as a liquid biopsy," Dr Park said.