Illumina's cancer diagnostics spinout, which is backed by a host of corporate investors, reached the $900m first close of the round in March.

Grail, the US-based cancer diagnostics startup spun out of genomics technology provider Illumina, has increased the size of its series B round to $1.21bn, according to a regulatory filing on Wednesday.

Founded in 2015, Grail has recruited thousands of patients for clinical tests that will be combined with high-intensity sequencing and data science technology in a bid to decipher the patterns necessary to detect several kinds of cancer, which could lead to earlier-stage diagnostic tests.

Venture capital firm Arch Venture…