BioPharma, Startups

Red blood cells with superpowers: Rubius rallies a $120M Series B

Red blood cells tend to mind their own business, but what if they could be engineered to replace missing enzymes, activate T-cells, or bind tumor cells? It's an exciting possibility that has garnered a highly oversubscribed $120 million Series B.

By Juliet Preston on June 21, 2017

On Wednesday, day three of the 2017 BIO International Convention, Flagship Pioneering is poised to make a splash.

The Cambridge, Massachusetts-based venture capital firm has announced a mega $120 million Series B for Rubius Therapeutics, a startup founded out of its innovation VentureLabs hub. 

In line with Flagship’s model for innovation, Rubius is working on a novel technology with a plethora of possible applications.

It all centers around the company’s Rubius Erythrocyte Design (RED) platform, which reengineers red blood cells into purpose-built therapeutic machines. The idea is appealing on a number of fronts, not least because red blood cells are naturally allogeneic — they don’t trigger an immune response. Any subsequent products could theoretically be used off-the-shelf. 

In a phone interview, Torben Straight Nissen, president of Rubius and a Flagship venture partner, noted that two major innovations have made the somewhat intuitive approach possible.

The first is the company’s ability to engineer red blood cells. If you took biology 101, you’ll recall that they don’t have a cell nucleus. There’s no one in the cockpit to give your orders to. To create a malleable cell, Rubius makes its intervention earlier on in the maturation process before the nucleus is expelled. That allows the team to engineer proteins within the cell or on the cell surface — even multiple different proteins if required.

presented by

The end product can interact with many different cells, for many different therapeutic applications.

“We can express enzymes within RED cells, whereby they are shielded from the immune system and also they will be circulating with the RED cell for up to 120 days,” Straight Nissen explained.

Enzyme replacement therapies are just the beginning. The RED cell therapeutics (RCTs) could be used to activate T-cells as part of a cancer immunotherapy approach. Or they could be programmed to bind tumor cells and trigger apoptosis directly. As Straight Nissen noted, solid tumors typically have well-established and leaky vascular systems, which makes RCTs the perfect therapeutic solution. For blood cancers, a blood-based approach is a no-brainer. 

In other fields, Rubius has performed some preliminary work gauging RCT’s potential in autoimmune, metabolic, rare, and infectious diseases.

The second technological leap Rubius has made relates to the final product. It also goes a long way to explaining the investor enthusiasm.

“What we’ve then been able to show reasonably, is that we can manufacture these engineered RED cells in bioreactors,” Straight Nissen said. “That now allows us to produce large quantities of cells and move into the clinic with a scalable manufacturing process.”

To further guarantee compatibility with all patients, Rubius is manufacturing its product using precursor cells from universal O-negative donors. Each patient will also undergo additional cross-matching prior to their first dose.

“One thing that makes us excited about this platform and working with RED cells is that there are decades, if not hundreds of years, of experience with blood transfusions and we’re really leveraging that whole infrastructure that already exists in the medical community to deliver our product,” he said.

At $120 million, the biotech’s financing was one of the largest recorded thus far in 2017 and “highly oversubscribed.” Straight Nissen said the company garnered a lot of interest from institutional investors and could have raised “significantly” more than the final sum. As it stands, he believes Rubius is well-positioned to execute on its strategy for the next three years, to the end of the first clinical readouts. 

It’s a pat on the back for Flagship, which made an initial $25 million downpayment to launch the company in 2015.

Photo: virusowy, Getty Images