Martin Mackay’s rare disease startup gets $145 million as it enters the clinic
Two years ago, Martin Mackay took a couple of fellow exiles from Alexion’s 2017 culling and, after 3 decades in Big Pharma and big biotech, struck out on his own, with a vague vision that was as small as it was broad. They called it Rallybio and it was going to focus on rare diseases — they just didn’t say which of the thousands of those rare diseases that would be.
Today, they did, disclosing the first of what they say will eventually be a list of programs. And the trio — which also includes former Alexion research head Stephen Uden and Alexion tax chief Jeff Fryer — raised $145 million in Series B funding to take into the clinic, grabbing capital from the aptly named Pivotal bioVenture Partners and 10 other investment firms.
First up is FNAIT, or fetal and new-neonatal alloimmune thrombocytopenia, a rare condition in which a fetus has antigen on platelet cells that a mother lacks. The mother, recognizing those antigens as foreign, can mount an immune attack, developing antibodies that target the fetus’ platelets, leading to bleeding, including sometimes in the brain. The disease is generally treated with close monitoring of the baby after birth, but Rallybio wants to prevent it, giving mothers an antibody that will turn down the immune response early in the pregnancy.
“The trick will be identifying mothers at risk,” Uden told Endpoints News, adding they can do that with a simple test already in use. “It would be a case of repurposing.”
Should the therapy work, the goal would be to have the screening become part of the routine rare disease tests women receive during pregnancy.
The goal “is not to use this to treat the disease but to fundamentally eradicate it,” Uden said.
The trial will begin in the second half of this year, at a single site in Germany, one of the countries that has done significant epidemiological work on the disease, with talks underway for how to screen a minimum number of mothers.
”It’s not like we’re a big company running hundreds of trials — they have undoubtedly been hit,” Mackay said. “The fact that we’re focused on a small number will help us steer our way through.”
When Rallybio launched in 2018, the founders had ideas for the disease they wanted to focus on, but the search picked up after the Series A in April. They established a network of essentially drugs scouts in countries from Israel to Japan, hoping to find serious illnesses whose biology was understood, a solution that seemed feasible but which simply hadn’t gotten sufficient attention from people with money and development experience.
Late that fall, Uden met with biotechs from Nordic countries on a wintry day in New York City, including the CEO of Prophylix, a biotech focused on FNAIT. Prophylix’s experience was largely academic, with few resources or history in business, but the disease and the treatment were fairly straightforward. A similar approach has long been in rhesus disease, a similar condition that matched red blood cells instead of platelets. It matched Rallybio’s criteria for a good candidate.
“How bad is the disease, how good is the biology, and can we come in with an intervention that will make a difference?“ Mackay said, describing their criteria.
Rallybio acquired Prophylix and signed deals with two others, but the goal is to ultimately have 4 to 8 programs at different stages of development. The business model depends on it, said Mackay. If you can bring in experimental drugs for several of these diseases, you can treat more patients, expand your revenue and derisk the platform.
“We want to build a sustainable company, we see that as the way to make the most meaningful difference in these rare and severe diseases,” he said. “To be a sustainable company you need a portfolio.”