
Barely two months after unveiling a new breed of radiopharmaceuticals, RayzeBio brings total haul to $150M
Just before Versant and venBio officially took the wraps off RayzeBio with $45 million in launch money, Ken Song reached out to a few other investors “just to give them an overview.”
He wasn’t necessarily looking to raise money immediately, the CEO said. Whereas the Series A came together mostly around the concept of a new radiopharmaceutical company, RayzeBio now had more details and progress around its pipeline to illustrate just what its platform can do. But the group — comprising some firms that were known for their crossover and public portfolios — became so enthused that, barely two months later, he has $105 million more to work with.
The plan is still to have at least one development candidate by the second half of 2021 and start the first clinical trials within a year of that.
“We can now definitely prosecute in parallel all of our programs without needing to make resource allocation decisions due to lack of capital,” he told Endpoints News.

With 13 now on the payroll and more set to join, Song also wooed Eric Bischoff, a colleague from his Metacrine days, to join as SVP of development and operations. Gary Li, the newly appointed head of biology and translational medicine, is tasked with getting the compounds ready for IND-enabling studies. Both join Song and Deborah Charych, co-founder and chief technology officer, on the senior team.
RayzBio’s programs, including the most advanced one in mid-stage lead optimization, have two parts: There are the peptide binders for a host of solid tumor targets, identified in screening by its Japanese partners at PeptiDream. These are then radiolabeled with Actinium-225 with the intent of sending the powerful radioisotope straight, and only, to cancer cells.
The biotech’s decision to make bespoke binders rather than repurpose molecules off-the-shelf proved appealing to investors, Song said. The VCs also liked that it had 7 programs, some of which would be first-in-class radiopharmaceutical products if they make it.
“Because if you look at most other radiopharmaceutical companies that are out there — I’m excluding Novartis, which is a large pharma — but if you look at pretty much everyone out there, most companies are pursuing maybe 1 or 2 programs at most. And many of those programs tend to be sort of the same tried and true targets that have already been pursued in radiopharma.”
A Venrock fund focused on publicly held and late-stage private plays led the round, with OrbiMed, Redmile Group, Viking Global Investors, Logos Capital, Cormorant Asset Management, LifeSci Venture Partners, Alexandria Venture Investments and others joining as new investors. Versant and venBio returned for more, alongside Samsara BioCapital.

Bong Koh from Venrock Healthcare Capital Partners is joining the board.
The new cash infusion will also fund an expansion of the San Diego headquarters as well as studies into RayzeBio’s manufacturing options. Making radioisotope-drug conjugates, after all, is a much different process than typical therapies, despite dramatic advances in the ability for early-stage developers to secure therapeutic radioisotopes.
For now, it’s going with a centralized model relying on key partners. But it could bring more of it in-house in the future — or try something else.
“I would say everything is still on the table in terms of determining what is the best manufacturing strategy to take forward,” Song said.