Wednesday 4 November 2015

How many liquid biopsies per year by 2020: in the UK it might be well over 1 million

I've been doing some work looking at CRUKs cancer incidence statistics and this is what sparked the idea for this post. There are just under 350,000 new cancer cases in the UK each year. Although ctDNA can be found in many/most tumour contexts (Bettegowda et al 2014), it may not be used universally. I'll assume that in all common cancers ctDNA sequencing, a "liquid biopsy"(not sure how Cynvenio got there first with the trademark - smart move), will be used as a first-line and/or follow up test run at least once per year per patient on average - by 2020. Assuming that patients will live for 10-20 years with their disease this works out at 1.75 million to 3.5 million tests per year. I'm sure people are doing much better modelling than me but by any measure this is a lot of sequencing tests to run!

Sequencing can seem difficult, however to be able to sequence all those tests someone's got to make 1,750,000+ libraries! An automation platform capable of processing 96 samples in 24 hours would need to run for fifty years! Or fifty labs would be required just to keep up with demand. Even at just £25 per sample for an amplicon based test (no-one is offering a test at this price today) the costs would be almost £50M-100M. This assumes that the cost of collecting samples is zero, and I'll totally ignore Bioinformatics which I think will disappear for simple analysis by 2020*.

Right now there are no library prep methods that truly allow you to go from sample to sequence in one day. Innovation here is going to be vital, and I suspect will become more and more the focus for investment. The company that can come up with a fast and robust method, and sell it to someone like the NHS in large volume is going to come out on top. Might we even get to a similar situation as with forensics where only a couple of tests are internationally recognised, making the sharing of data much easier?

NIPT is being rapidly adopted partly because the tests have been rapidly defined - the coverage required for a specified sensitivity/specificity is known. Somatic sequencing is tougher due to lack of clarity of the sensitivity required to have a clinical impact. Clinical trials are happening now but it might remain an open question for a while as to whether you should swap to a different drug, e.g. EGFR inhibitor, or combination, when e.g. T790M gets to 1%, 10% or 50% mutant allele frequency.

Worldwide there are over 14 million new cancers per year, if the logic above translates then the number of tests climbs fast - maybe 150M liquid biopsies per year.

*Whilst the bioinformatics challenges are huge right now I do believe that we'll have well developed pipelines that can call mutations and generate clinical reports with minimal effort for "simple" cancer panels by 2020.

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