Orca Bio Earns FDA Approval for Its Next-Generation Bone Marrow Transplant

On June 30th the FDA granted approval to Orca Bio’s next-generation bone marrow transplant, Tregzi. 8VC has been a proud investor since leading their Series B in 2019.

For more than half a century, a stem cell transplant has been the best chance, and often the only chance, at curing blood cancers like leukemia. But it has carried a serious risk. The same donor immune cells that attack a patient's cancer can also attack the patient, a condition called graft versus host disease (GvHD). It is common, it can become chronic and disabling, and it can be fatal. The danger has been great enough that many older or frailer patients were never offered the transplant that might have cured them.

The deeper problem was biological. The graft's power to kill cancer, known as the graft versus leukemia (GvL) effect, and its tendency to harm the patient looked like two sides of the same coin. The patients who got the benefit were often the ones who paid for it. Irv Weissman's lab at Stanford, and the company it spun out, SyStemix, pioneered a bold idea decades ago: that you could purify the graft and pull those two effects apart. The biology was sound. But the company was eventually shelved, because no one could manufacture cells at the purity and speed a hospital requires. So the idea sat, largely doubted, for more than thirty years. 

Orca Bio was finally able to prove this.

Instead of infusing a donor's cells as one unsorted mixture, Orca rebuilds the graft from precisely measured cell populations, including a purified dose of regulatory T cells, the immune system's own peacekeepers, to hold the disease down while keeping the cells that fight the cancer. Modern manufacturing caught up to decades of biology, and it worked.

Here is what that means for patients. In the Phase 3 trial, people who received Orca's therapy were twice as likely to be alive and free of chronic graft versus host disease a year later, 78% versus 38%. The chronic form occurred in 13% of them, compared with 44% after a standard transplant, and survival at one year was 94% versus 83%. 

Orca’s work goes beyond statistics. In the middle of their trial, CEO Nate Federoff’s 71 year-old father-in-law was afflicted with leukemia and exactly the patient Orca was meant to treat. They expanded access to put him on the therapy, and today, more than three years on, he is alive and in remission.

That kind of conviction is exactly what we look for, and it is why we were willing to do something unusual. Orca was never a conventional life science bet. The common path is to develop a promising asset and sell it to a large pharmaceutical company. A personalized cell therapy is not that kind of asset. It needs its own manufacturing, its own logistics, and its own commercial engine. It required investors willing to help build an enduring company and bring the product to patients directly, rather than hand it off. That is the kind of company we exist to back. We first invested in Orca in 2019, at their Series B, and we have been in every round since.

And this is the first approval, not the last. For decades, transplant has hinted at what it could do well beyond the cancers it treats today. It is what functionally cured the Berlin patient of HIV, and it can reset the immune system in severe autoimmune disease like multiple sclerosis. What held it back was the toxicity, which confined it to the sickest patients who had no other choice. Lower that toxicity, and you change both what transplant can treat and how many people can safely receive it. This is why we believe cell therapies are the third great wave of medicine, after small molecules and biologics.

Congratulations to the entire Orca Bio team. This is a milestone for them, and for the patients and families who will benefit for years to come. Onward.

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