Jasper Therapeutics launches out of Stanford with new approach to stem cell treatment
The first girl in the trial came in with chronic diarrhea and the immune system of an untreated HIV patient. Born with a rare genetic disease that impeded her ability to make B and T cells, she had once been given a stem cell transplant but it didn’t take. Back in the hospital, she was injected with a new experimental antibody and then given a new stem cell transplant. Soon, she gained weight. The diarrhea stopped.
“She has normal T cells now,” Judith Shizuru, the Stanford scientist who pioneered the antibody, told Endpoints News. “She’s in school.”
It’s the kind of medical story to launch a biotech around. Today, Shizuru’s company Jasper Therapeutics is emerging out of stealth-mode with $35 million in Series A funding led by Abingworth and Qiming, a molecule from Amgen, and a Phase I trial set for its first readout on Monday at ASH.
Jasper is broadly aimed at making stem cell transplants safer, more accessible and more effective by using antibodies as conditioning agents. These agents clear out bone marrow to make room for the new stem cells to graft onto the body.
The new company is one of a handful now using antibodies to help ease stem cell transplantation. California-based Forty Seven is testing a combination of two antibodies, a c-Kit and a CD-47, in monkeys. In Cambridge, Mass., Magenta Therapeutics is working on a c-Kit that releases a toxin after it binds.
Jasper’s Phase I uses a naked antibody called JSP191 to help patients with severe combined autoimmune deficiency receive stem cell transplants – the only possible cure for the life-threatening disease – but such transplants are used in a wide variety of conditions and Jasper has broader aims. Those include other autoimmune diseases, acute myeloid leukemia and cell-directed gene therapy.
“There’s a significant amount of progress being made in gene therapy,” interim CEO William Lis told Endpoints, “but no progress being made in a conditioning agent that will help graft gene therapy.”
Shizuru path to the new antibody was long and fortuitous. In 1987, Arl Arzst, the legendary ad executive and president of Proctor and Gamble international flew in on a recruiting trip for Stanford business students. There he visited Shizuru, a young biology PhD candidate, because he knew her roommate. Arzst’s daughter had diabetes and as Shizuru explained the work she was doing on pancreatic islet cell transplants, he told her to come to Europe.
Shizuru had never been to Europe, but there Arszt introduced her to Ken Farber and the other founders of the Juvenile Diabetes Foundation (now the JDRF). The founders struck a years-long correspondence and encouraged Shizuru to go to medical school, where she decided that if scientists were ever going to develop transplants that didn’t trigger an immune response, it would be through stem cell work. She continued her work at the Irv Weissman’s Stanford regenerative lab, where eventually a graduate student made a discovery that piqued her interest.
To put new stem cells in, you have to get the old stem cells out. That’s not always easy. The cells sit in these pockets in the bone marrow, and they’re pretty comfortable there. Doctors have to force them out, often using chemotherapy or radiation, which damage DNA and cause severe side effects. The costs sometimes outweigh the benefits.
“There are diseases we’re not treating because it’s too dangerous,” Shizuru said. “And the kids we’re treating, they’re so, so fragile.”
The grad student had shown in mice that antibodies could be used to deplete the stem cells and potentially eliminate the need for chemotherapy or radiation. Shizuru and her team began looking to see if anyone had developed a human version of the antibody, CD117. It turned out Amgen had already developed a version of this antibody for a different use. It also turned out she had a former postdoc and a former advisor who worked there. They began a collaboration.
“We set out to cross the valley of death,” Shizuru said, using an industry slang term for the jump from animal models to human uses.
After making a variety of tweaks to the treatment, they published a paper in Science Translational Medicine in 2016 showing the antibodies created a 10,000 fold reduction in the number of stem cells in mice.
The same year, they began a clinical trial on 90 SCID patients. These patients had received stem cell transplants when they were very young but hadn’t been given chemo or radiation for fear the side effects would be too severe. The original transplants boosted their number of immune cells, but without chemo or radiation, the stem cells don’t graft into those pockets and the body won’t continue producing T cells. Without those, they are extraordinarily prone to infection. Many pass away before age 2.
The hope is that the antibodies allowed the stem cells to graft, and the preliminary answer to that question will be out on Monday. For the first girl in the trial, life has improved but questions about how long her body will make immune cells remain. Still, for that girl and others, Shizuru is confident.
“We see there is stem cell engraftment,” Shurizi said. “They are actually making new T cells.”