Buoyed by long-term organ transplant data, ITBMed bags $67M to advance ex-MedImmune asset

Seven of the transplant patients who received siplizumab were weaned off immunosuppressants for four or more years. (pasja1000)

ITBMed has raised $67 million (€55 million) to advance siplizumab in organ transplant patients. The ex-MedImmune monoclonal antibody impressed in a 10-patient trial, raising hopes that ITBMed can snag a limited, near-term approval while running a pivotal study to expand its use. 

Royalty Pharma CEO Pablo Legorreta, who thinks siplizumab could be “a really large drug,” led the round. 

Stockholm, Sweden-based ITBMed set up shop in 2016 to build on research performed at Massachusetts General Hospital (MGH), where David Sachs, M.D., and his collaborators tested siplizumab in patients who were undergoing HLA-mismatched kidney transplants. Such transplants are typically associated with inferior outcomes than HLA-matched donations, but many of the MGH patients thrived.

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The findings carry the caveat that they come from a single-arm trial of 10 patients. But ITBMed thinks the results are impressive and is talking to regulators about what else, if anything, it will take to get the drug to some patients in the real world.

“There is strong data from these 10 patients and, from our perspective, there could potentially even be a claim that certain populations of patients could benefit from such a treatment today,” ITBMed CEO Erik Berglund, M.D., Ph.D., said. Berglund, a transplant surgeon, and his brother David, an immunologist, set up ITBMed with MGH’s Sachs.

Sachs and his collaborators put 10 transplant patients through a conditioning regimen featuring the anti-CD2 antibody siplizumab. Seven of the patients were weaned off immunosuppressants for five or more years. Three of the patients later restarted on a low dose of immunosuppressant but, at the time the data were published, the rest had remained off the drugs for as long as 11 years and counting. 

The data suggest the regimen may enable surgeons to transplant any organ into any patient, without also subjecting them to a lifetime of immunosuppressants and the associated risk of infections and malignancies. Siplizumab also looks to cut the risk of chronic rejection of organs.

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ITBMed’s antibody is thought to achieve those outcomes through its targeting of the CD2 protein found on immune cells, particularly memory T cells. Binding to the cells stops them from identifying the transplanted organ as foreign and thereby dials down the attack on the implanted tissue. 

The MGH team also gave donor bone marrow alongside each transplanted kidney. That contributed to the host immune systems temporarily being made up mostly of donor cells. The proportion declined over the days and weeks following the transplant, but the presence of donor immune cells may tip the odds in favor of the transplanted organ early on.

“You're essentially giving the recipient of the kidney the immune system of the donor,” Legorreta said.

The next step for ITBMed is to wrap up the regulatory talks. That could open up a limited piece of the market, but the company expects to run a larger, pivotal trial to secure a broad approval. To bankroll that effort, ITBMed has turned to a syndicate led by Legorreta. 

Siplizumab’s progress in organ transplants is writing a new chapter for a drug that looked to have fallen away more than a decade ago. Working with BioTransplant, MedImmune put siplizumab—then known as MEDI-507—through trials in several indications starting about 20 years ago, generating safety data in more than 400 patients along the way. But the now-AstraZeneca unit’s interest in the asset waned after midphase psoriasis data suggested it would struggle to match the efficacy of drugs such as Enbrel and Humira.   

That closed off development of siplizumab in one indication, but the team at MGH picked up the baton several years later, leading to the data that enabled ITBMed to put together the $67 million round.