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How Big Data Can Help Fight Cancer

cancer.nautil.us

21–30 of 31 posts

Re: How Big Data Can Help Fight Cancer

#21
post #18
post #16

Earlier quoted context omitted.

This editing procedure is extremely toxic, and I do not believe this is all due to off-target effects. I found this one quickly, where the paper claimed 80% viability when their data showed something more than half of them "go missing" (impossible to tell more from the chart): https://news.ycombinator.com/item?id=12971533 Here is actually one where they injected into Drosophila embryos. It looks like to get 10% succe…

Certainly. That is with unaided, wild-type Cas9, 4 years ago. The understanding (and mitigation) of what causes those side-effects is under some of the most comprehensive and intense research as we speak. Searching PubMed for 'Cas9' shows that 2000 papers (of a total of 3200 results) have been written in the last 16 months. And there are other ways to edit genomes - Cas9 is great for research because it's fast, but t…

Is there a less toxic (but equally effective) cas9 available, or are you saying this is still under research? Sorry, I do not feel like searching around right now.

Re: How Big Data Can Help Fight Cancer

#22
post #21
post #18

Earlier quoted context omitted.

Certainly. That is with unaided, wild-type Cas9, 4 years ago. The understanding (and mitigation) of what causes those side-effects is under some of the most comprehensive and intense research as we speak. Searching PubMed for 'Cas9' shows that 2000 papers (of a total of 3200 results) have been written in the last 16 months. And there are other ways to edit genomes - Cas9 is great for research because it's fast, but t…

Is there a less toxic (but equally effective) cas9 available, or are you saying this is still under research? Sorry, I do not feel like searching around right now.

Off the top of my head:

Entirely new (smaller, thus more engineerable) Cas systems (1 month ago): http://www.nature.com/cr/journal/v27/n3/full/cr201721a.html

Variously engineered Cas9 proteins to reduce toxicity the over wild-type protein (two months ago): https://www.ncbi.nlm.nih.gov/pubmed/28179977

Cas9-Inhibitors to help regulate activity (two months ago) http://www.cell.com/cell/fulltext/S0092-8674(16)31683-X

And this doesn't include any ongoing research using other homing nuclease technologies like TALENs and Zn-Fingers that provide an entirely different set of tradeoffs but aren't as sexy, in part because they're harder to use.

Re: How Big Data Can Help Fight Cancer

#23

Earlier quoted context omitted.

> 1) Exome sequencing is below $1000, but analyzing that data adds a non-negligible cost. That is by and large the most significant factor that we've seen which slows adoption of more widespread whole-exome or whole-genome sequencing. It takes less than a day and costs less than $1000 to sequence your exome (and even your whole genome), but the backlog for analysis of the sequencing results in labs can be 9 months or…

> It takes less than a day and costs less than $1000 to sequence your exome (and even your whole genome), but the backlog for analysis of the sequencing results in labs can be 9 months or more. Layman qs. what is stopping the labs to quickly analyze the genome? Computational power or few labs doing this kind of work?

It's mostly not about computational power. The stitching together that jfarlow mentions is part of the "secondary" analysis where the raw genome data must be put together, but that's mostly a solved problem, as there are plenty of gold-standard open-source libraries that employ statistically complex calculations to align raw data to the current version of the human reference genome. That's part of what takes less than a day along with the primary sequencing. It's constantly being improved, but most labs would not consider this an issue that keeps them up at night, as what we currently have works reasonably well.

The part that takes a long time (i.e. the "bioinformatics bottleneck" I referred to), is that once the sequencing data is stitched together, you end up with a ton of variants, and you don't know which (if any) are clinically significant.

Imagine that each nucleotide in your genome is a marble, and that the entirety of your sequenced genome is a 1-story building filled with marbles (that's how many nucleotides are in your genome), and that each one is supposed to be a specific color out of 4 possible colors. Now imagine that 10,000 (or more) of those marbles are the wrong color.

Primary analysis (putting your sample into a machine and essentially getting back a list of what color all your marbles are), as well as secondary analysis (i.e. the process of sorting your marbles into the correct order so that you can actually tell _which_ marbles specifically are the wrong color) together are what cost less than $1000 and take less than a day.

The real problem is that you may find that 10,000 (or more) of your marbles are the "wrong" color, but 9,900 of them make absolutely no difference in a clinical sense. To be clear, a marble that's the wrong color is a "mutation", or "variant". Maybe this mutation makes my eyes slightly bluer, or my finger nails a little harder.

In other words, the part that takes a long time is actually going through each mutation and figuring out which one (out of the 10,000 variants) is clinically significant or relevant to the disease/symptoms you seem to have, and then figuring out if there's a known treatment for that particular root cause. Currently, this is done by employing MD PhDs to look through each patient's sequenced data, and then cross-referencing that with the millions of published studies to see what has ever been seen before, or is known to be associated with some disease.

And it can take a human hours to a day to do this per patient. So, the number of patients times the amount of time it takes per patient, divided by the number of MD PhDs a lab can hire to do this, is what leads to the backlog.

So, actually yes, it is computational power... but it's human computational power.

Re: How Big Data Can Help Fight Cancer

#24
post #13

Earlier quoted context omitted.

In general it's a (computationally) hard problem to restitch a genome together. Even today, when you 'get your genome sequenced' you are not getting a full read-through of your entire genome's data. Imagine you want to reconstruct the data on two RAIDs that are mostly, but importantly not exactly, mirrors of each other. Each RAID has 23 drives. Each drive has ~1Gb or so of data. And much of the data is not only mirro…

hmm I don`t think so I fathom the complete complexity of the process but with so many powerful GPU`s out there, is there a possibility of reconstruction in a matter of days if not hours?

Yes, it depends on the size of the sequencing panel that was done (i.e. a targeted panel for a specific gene or set of genes versus whole exome versus whole genome). But even for whole exome, you're talking a few hours or faster depending on hardware.

In addition to our company, Genomenon (which seeks to speed up the interpretation time required to analyze the data _after_ it's been computationally aligned and annotated), I'm also friends with another startup down the street, called Parabricks, which seeks to speed up this alignment process (aka secondary analysis) even further.

Re: How Big Data Can Help Fight Cancer

#25

As whole-exome sequencing has now dipped below $1,000 [1], this really should become a diagnostic assay of first resort. That said, further improvements are required as it appears the majority of cancer causing sequence variants are found in non-coding regions of the genome [2], suggesting that greater sequencing coverage is tremendously valuable. [1] https://www.genome.gov/sequencingcosts/ [2] http://www.nature.com/…

Cancer genomics researcher here. I agree wholeheartedly about getting sequencing done if you have cancer - it's what I would do for myself or my family. Two minor quibbles about your thoughts: 1) Exome sequencing is below $1000, but analyzing that data adds a non-negligible cost. Still, even 2 or 3 grand is way cheaper than wasting time on treatments that won't work. Whole-genome sequencing is even better (for a litt…

> The bottom line is, If you get cancer, fight like hell to get your tumor sequenced. Most insurers cover at least some kind of genomic test for cancer these days.

Is this something that has to go through your oncologist or can you drive the process independently?

Re: How Big Data Can Help Fight Cancer

#26

Earlier quoted context omitted.

> It takes less than a day and costs less than $1000 to sequence your exome (and even your whole genome), but the backlog for analysis of the sequencing results in labs can be 9 months or more. Layman qs. what is stopping the labs to quickly analyze the genome? Computational power or few labs doing this kind of work?

It's mostly not about computational power. The stitching together that jfarlow mentions is part of the "secondary" analysis where the raw genome data must be put together, but that's mostly a solved problem, as there are plenty of gold-standard open-source libraries that employ statistically complex calculations to align raw data to the current version of the human reference genome. That's part of what takes less tha…

I'm curious if you think your primary sequence data is strong enough to support confident automated lookups. Do you computationally prioritize the mutations prior to human annotation? If your primary sequence is good enough it should be pretty straightforward to look for coding sequences, mutations which create truncations, mutations which change amino acid charge, mutations in proteins known to be oncogenes, etc.

Re: How Big Data Can Help Fight Cancer

#27
This is my peers thesis. I may be doing this type or along this line.

I think the problem is big data, in a non statistican sense, where you cannot get large amount of observation from patient. Either because of legal loop holes and/or the cost of getting enough patients for experiment and trials. This is for trials.

Even with phase III clinical trial it's less than 200 obs. This is not big data in the non statistician world. In our world big data mean tons of predictors. Medical data is usually high dimensional, less obs but tons of predictors, more columns than rows.

Also hospitals are wary of giving out data, either because of legal issues or because they know it's valuable so they don't want to share it. These two issue is compound it on the fact that the infrastructure is not there to share the data in one spot, it's fragmented across many other databases with different schema and what not.

But my peers and I have thesis involving cancer using genetic data. It's very promising, one of the recent thesis is about base on genetic data if the patient should take the surgery route or the chemo route and the model had a 80% accuracy rate and nice sensitivity rate (forgot what it was). The prediction is survival rate.

I also saw other comment about using genetic data against them. I think this is FUD because we have a law in place, GINA.

Re: How Big Data Can Help Fight Cancer

#28
post #26

Earlier quoted context omitted.

It's mostly not about computational power. The stitching together that jfarlow mentions is part of the "secondary" analysis where the raw genome data must be put together, but that's mostly a solved problem, as there are plenty of gold-standard open-source libraries that employ statistically complex calculations to align raw data to the current version of the human reference genome. That's part of what takes less tha…

I'm curious if you think your primary sequence data is strong enough to support confident automated lookups. Do you computationally prioritize the mutations prior to human annotation? If your primary sequence is good enough it should be pretty straightforward to look for coding sequences, mutations which create truncations, mutations which change amino acid charge, mutations in proteins known to be oncogenes, etc.

This is currently done; it's part of the filtering and annotation process that happens at the tale end of the secondary analysis. Everything I'm talking about comes after that. This is part of why the human interpretation part takes hours to a day, instead of a day to several days.

However, it's far from perfect and can always be improved. That's one of the things we're trying to help with, is to do further pre-processing on the knowledge-base of all genomic information contained in all published literature, to try to drive the current hours-to-a-day timeframe down to minutes-to-an-hour, or just minutes.

One issue though, is that it's a constant tug-of-war optimizing between false-positives (giving you too many variants to manually review) and false-negatives (removing variants due to some data threshold which may have been clinically significant).

Re: How Big Data Can Help Fight Cancer

#29
post #22
post #21

Earlier quoted context omitted.

Is there a less toxic (but equally effective) cas9 available, or are you saying this is still under research? Sorry, I do not feel like searching around right now.

Off the top of my head: Entirely new (smaller, thus more engineerable) Cas systems (1 month ago): http://www.nature.com/cr/journal/v27/n3/full/cr201721a.html Variously engineered Cas9 proteins to reduce toxicity the over wild-type protein (two months ago): https://www.ncbi.nlm.nih.gov/pubmed/28179977 Cas9-Inhibitors to help regulate activity (two months ago) http://www.cell.com/cell/fulltext/S0092-8674(16)31683-X And…

I didn't see any data on improved survival/toxicity in those papers. The closest was Fig S4B/C of the last one (Rauch et al 2017), which shows some of the inhibitors are toxic too. So evidence for that may exist somewhere, but not there.

Also, I think if they were serious about addressing this toxicity issue they would be include simple charts of the number of cells over time and number of "modified" cells over time. Then they (and the reader) can easily compare the toxicity and efficacy of different techniques.

Re: How Big Data Can Help Fight Cancer

#30
Sequencing DNA in archival specimens like Foundation has significant limitations. The ability to predict drug responses from this data alone seems quite limited. For example, the most common alteration, loss of function variants in TP53, is not at present druggable.

Additionally, one of the greatest revolutions in cancer therapy - immunotherapy - does not have a great genomic-based predictive biomarker (Foundation Medicine has created a surrogate test using mutation burden, but this is not really good enough, and not validated prospectively).

So DNA sequencing is only part of the story. Some tumours in particular seem driven by epigenetic changes, or structural variants that Foundation cannot detect.

Sequencing is in a place where it has reached technical maturity, and has collided with big data hype. But in reality, the benefit to patients will be incremental. There is at present zero good quality evidence that panel based genomic screening like Foundation Medicine provides improves patient outcomes as a general strategy.

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