Stem cell transplants can effectively cure a wide range of diseases, from blood cancers to rare genetic disorders. They've been used for decades and are considered standard treatment for certain conditions.

But for a good number of patients, stem cell transplants are out of reach. Drug regimens used to prepare the body for a transplant are toxic and can cause serious side effects. The transplanted cells don't always "engraft," or take root in the bone marrow. Even when they do, patients' disease may linger or recur.

A biotech startup launching Wednesday with $50 million in funding hopes that, by combining cell, antibody and gene editing technologies, at least some of these problems can be overcome. Called Cimeio Therapeutics, the new company is led by a team of pharmaceutical industry veterans and an advisory board filled with scientific luminaries, including immunologist Jeffrey Bluestone and gene editing pioneer Fyodor Urnov.

Cimeio's approach involves "shielding" transplanted cells by genetically editing them in ways that allows paired immunotherapies to be safely used both before and after a transplant.

Thomas Fuchs

Courtesy of Cimeio Therapeutics

"We think that this can really unleash the power of hematopoietic stem cell transplant and make a lot more patients eligible for it," said Thomas Fuchs, Cimeio's CEO and a former Genentech executive.

The "shielding" technology used by Cimeio was developed in Switzerland at the laboratory of Lukas Jeker, a physician-scientist from Basel University Hospital who will join Cimeio as head of gene editing.

Jeker's lab discovered that protein receptors on the surface of cells could be genetically edited in such a way that prevented antibodies from binding to them, while leaving their function intact. In preclinical testing, these edits could cloak, or "shield," the cells from being depleted by antibody drugs and T cell therapies.

The work could have powerful implications for improving stem cell transplant and adoptive cell therapy, according to Fuchs.

Once a stem cell or T cell is shielded, a complementary immunotherapy could be used to either help ready patients for a transplant or to further treat disease afterwards, he said. "Maybe you could give a cycle or two of the paired immunotherapy, implant the shielded cells and then continue to administer the immunotherapy," he added.

If the shielding works as intended, Cimeio could develop treatments for conditioning that are more tolerable than the chemotherapy or radiation-based regimens currently in use. Shielding might also allow existing drugs that target cell proteins on healthy as well as diseased cells to be used more flexibly with transplants, such as to treat residual disease that lingers afterwards.

For example, Cimeio could engineer stem cells that are protected against binding via a protein called CD19 that's often the target for CAR-T therapies that treat lymphoma, but is also found on healthy B cells that help the immune system fight off threats.

"One benefit could be that you could prevent a lifetime of B cell depletion, which happens when you give a CAR-T," said Fuchs.

Alex Mayweg

Courtesy of Cimeio Therapeutics

Cimeio was built from Jeker's lab by Versant Ventures at the company's "Ridgeline" incubator in Basel, which has previously produced companies like Monte Rosa Therapeutics and Black Diamond Therapeutics. The initial $50 million Versant provided will fund Cimeio through next year, said Alex Mayweg, a managing director at the venture firm and a Cimeio board member. Additional investors will be brought on later this year or early next, Mayweg said.

Cimeio will need the money, as its research and development plans are expansive. The company has identified four drug candidates already and envisions a dozen more behind those, said Fuchs. Its research spans blood cancers, rare genetic diseases and autoimmune disorders.

In some cases, Cimeio will develop paired immunotherapies to go with the shielded cells. In others, it will use existing treatments. Three of the first four candidates involve protecting hematopoietic stem cells, while the fourth involves T cells. The company hopes to begin human testing next year.

Cimeio plans to choose gene editing technologies based on the type of alteration it needs to make to shield cells. "Rather than building up an internal editing capability," Mayweg said, "we wanted to stay as flexible as possible."

That might mean partnerships or alliances with other companies, some of which have reached out to Cimeio already, according to Mayweg.

Cimeio is aided by a group of scientific advisers notable for their work in areas the company is focusing on. Urnov, of the University of California, Berkeley, is well known for his research in gene editing using zinc finger nucleases and CRISPR. Bluestone previously led the Parker Institute for Cancer Immunotherapy and is CEO of the cell therapy-focused biotech Sonoma Biotherapeutics.

Suneet Agarwal, a co-program leader of the stem cell transplant center at Boston Children's Cancer and Blood Disorders Center, is also on the advisory board, while Cimeio has a research collaboration in place with Matthew Porteus, a gene editing specialist at Stanford University.

About 20 people currently work at Cimeio directly, a number Fuchs expects will grow as the company's research advances. Another 15 are currently supporting Cimeio from Versant's Ridgeline group.

Read more:
Versant-backed startup launches with plans to broaden cell therapy's reach - BioPharma Dive