A startup that's building an unprecedented test for cancer just raised $900 million from major drugmakers and Amazon

A startup that wants to build a blood test to screen for cancer just raised more than $900 million.

Grail was created in January 2016 by gene-sequencing giant Illumina, and was originally funded by its former parent and a group of Silicon Valley investors including Jeff Bezos, Bill Gates, and Google Ventures.

Now, it's pulling in more big names from the pharmaceutical, tech, and healthcare industries:

• Johnson & Johnson Innovation, which led the round along with ARCH Venture Partners
• Amazon
• Bristol-Myers Squibb
• Celgene
• McKesson Ventures
• Merck
• Tencent Holdings Limited
• Varian Medical Systems

This is just the initial close, Grail said in a release. It's still expecting to raise more than $1 billion in its series B after a second close with life sciences institutional investors.

The initial funding is already the largest to date from a medical diagnostics company, though it's not alone in the field. On Wednesday, Freenome, another startup that wants to build out a blood test that screens for the earliest signs of cancer, raised $65 million in a series A round. And between 2015 and 2016, medical diagnostics companies raised roughly $1.8 billion.

The idea behind a cancer-screening test is to identify the tiny bits of cancer DNA that are hanging out in our blood but currently undetectable. If Grail or Freenome are successful, the companies would be the first to pull off a cancer-detecting blood test that works proactively. The concept is similar to liquid biopsy tests, which use blood samples to sequences genetic information in that blood to figure out how tumors are responding to a certain cancer therapy.

With one sample of blood (the same you might have drawn at the doctor's to check your cholesterol or blood sugar levels), Grail's plan is to sequence and screen for those bits with the hope that it will help catch cancer before it starts to be a full-blown problem.

But getting a test that will be accurate will take a lot of time and require huge clinical trials. Fast Company reported one trial that will take place in the United Kingdom with as many as 500,000 people. Another trial, called the Circulating Cell-free Genome Atlas study, launched in December 2016.

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