Ion Genomics Newsletter: May 19, 2026
Making sense of MRD regulatory news. Also: Blank Bio, Friday Happy Hour, Thaysen in China.
The FDA approved Natera’s Signatera as a companion diagnostic for a Genentech immunotherapy in muscle-invasive bladder cancer, a milestone that marks the first blood-based molecular MRD test to clear this regulatory pathway. The decision came as Veracyte and Personalis also announced Medicare coverage expansions for their respective MRD tests.
The FDA’s Signatera decision marks the first time a blood-based molecular MRD test has been cleared as a companion diagnostic (CDx.) It allows clinicians to use the test — which essentially says whether the tumor has returned following initial treatment — to guide treatment decisions such as initiating immunotherapy in positive patients and potentially deferring treatment in those who test negative.
Approval as a CDx means the test is now a prerequisite to prescribing this particular drug, but in the bigger picture for Natera, this week marks the moment that Signatera transitions from a promising lab-developed test with solid evidence behind it into a mandated, reimbursement-protected component of a standard treatment pathway. Now, the company can try to replicate this success across the other cancer types that it has designs on penetrating, including breast and ovarian, lung, and colorectal cancers.
This is a big deal for MRD testing in solid tumors, which is driven by detecting tumor DNA fragments in blood. This class of test is poised to become integral to treatment of solid tumors, which account for the majority of new cancer cases in the US.
When I was at the American Association for Cancer Research meeting last month, I attended a keynote session on the use of MRD in solid tumors that opened my eyes to the utility of these tests. I had previously considered them as a nice surveillance tool to catch recurrence. This is partly true: if your blood-based molecular signal returns, you’re extremely likely to have cancer recurrence. (This is helped by the fact that tests like Signatera are “tumor informed,” meaning they sequence a patient’s particular tumor with its particular mutations, a kind of a molecular “most wanted” poster.)
What I didn’t understand is that for many solid tumors, surgery alone is enough to drive remission in something like 50 percent of cases. Still, those 50 people get treated with toxic chemotherapy because studies show that overall survival is improved when 100 out of 100 people get that chemo. If you get an MRD test and it shows no signs of cancer, maybe your doctor is more comfortable in not prescribing that chemo.
If your tumor is going to come back, however, you may want a more aggressive treatment option provided by immunotherapy. For MIBC, that immunotherapy is now gated by Signatera. MRD testing can help predict recurrence sooner: a 2015 study in Science found that in breast cancer, MRD offered an eight-month headstart. And if you’re a pharmaceutical company trying to develop an immunotherapy and show a measurable extension of survival time, you don’t want those people who were good with just the surgery in your control group.
Investors have already caught on to this story. As noted by The Wall Street Journal’s David Wainer last week, Natera has seen its stock price quadruple in three years and is now valued more than Illumina ($28.22 billion to $21.24 billion,) even though Illumina provides the sequencing technology underlying Signatera. The CDx designation could further accelerate adoption.
Bladder cancer accounts for only 30,000 new cases in the US each year, but if it’s any indication of what’s to come with other solid tumors, MRD testing is about to explode.
Thanks to everyone who has checked out the video from my live happy hour on Friday, May 15. I lucked out as Jason Gammack, CEO of Ansa Biotechnologies was able to jump from the audience into the livestream. I’ll be hosting more of these in the future, albeit with more advanced notice. If you’d like to volunteer to join as a guest, send me a message or an email at ahan@iongenomics.bio.
May 15, 2026 Happy Hour Livestream - Video
Thank you to those who tuned into my live video! This turned out really well as Jason Gammack, CEO of Ansa Biotechnologies was able to jump from the audience and into the livestream. We spoke about the scientist he has been hyping up to the Nobel prize committee; AI’s prospects to change the life sciences; and our mutual connection to Madison, Wisconsin.
Aside from the MRD regulatory news, several funding announcements caught my attention this week.
In 2021, I wrote about a new method called RABID-seq which used a modified rabies virus to track cell-to-cell interactions in the brain. The modified virus deposited barcodes in each cell it infected, showing how cells were communicating. Now, Violet Therapeutics, a company trying to use that method to find new drug targets in neurodegenerative diseases, has raised $4.8 million.
Blank Bio, a startup founded by several associates of Bo Wang’s lab at the University of Toronto, announced a partnership with Pacific Biosciences to sequence RNA to feed its AI models and a $7.2 million seed financing round.
They’re convinced that RNA data can help them predict patient prognosis and response to treatment in cancer and they’re building models to help with patient selection in clinical trials.
It’s not immediately clear whether Wang, who developed scGPT and is a cofounder of Xaira Therapeutics, is involved in Blank Bio. Blank Bio did not immediately respond.
Avant Genomics, a University of Virginia spin-out developing automated sample preparation tools for liquid biopsy, has raised more than $3 million to advance its platform.
India’s Datar Cancer Genetics said it has received FDA clearance for CellDx-Tissue, its comprehensive genomic profiling assay for solid tumors.
And early last week the Translational Genomics Research Institute announced that Nhan Tran would join as VP of Cancer Discovery and Translation and codirect its Immunology and Microbiome Division. Tran comes to TGen from the Mayo Clinic.
Elsewhere on the Internet
Illumina CEO Jacob Thaysen quietly joined President Donald Trump on a recent visit to China, joining a host of other business leaders from US finance and technology companies, according to a report from Huanjia Zhang at GenomeWeb. Thaysen’s inclusion has not been well publicized by Illumina, which has not been able to sell new instruments in the country since being placed on a government blacklist in February 2025 and has seen revenue from the country continue to fall.
In a May 19 LinkedIn post, Thaysen said “it was a privilege to join President Trump” and suggested his participation came at the invitation of the US government.