Artbio, a start-up with a focus on developing radiopharmaceuticals to treat cancer, pulls its name right from its medicines—alpha radioligand therapies (ART). The nascent firm, with roots in Norway, debuted June 21 with a $23 million seed financing. Its drug candidates feature the α-particle-emitting isotope-212Pb, which is tethered to a cancer-targeting ligand. Two of its programs are based on small molecules, according to CEO Emanuele Ostuni.
212Pb has a relatively brief half-life of 10.6 h. “We think that the short half-life of lead may be an advantage over longer-lived isotopes, because of that ability to quickly deliver a lot of energy,” Ostuni says. “And because of the short half-life, we think the patients will recover more quickly, and be ready for more doses.”
Most radiopharmaceuticals that have been approved by the US Food and Drug Administration are β-emitters; the only FDA-approved α-emitter, called Xofigo, was invented by a team that included Artbio’s scientific founders, Roy Larsen and Øyvind Bruland. But α-particles hold a few advantages over β-particles, according to Ostuni, a former exec at Novartis Oncology. When they reach their targets, α-particles break both strands of DNA, while β-particles manage to cleave only one—a damage that some tumors can circumvent, he says. Also, α-particles don’t penetrate as deeply. This localization of the ionizing radiation poses fewer risks to nearby healthy tissues.
Many radioactive drugs can also inflict damage on the kidneys, as the peptides that often deliver the drugs can get stuck there, according to Otsuni. He says that using small molecules may allow the drugs to clear the kidneys faster, although he notes there have been recent advances in reducing peptidic absorption there. Small molecules may also be able to target tumors more specifically than peptides, he says. The company is pursuing both peptide and small-molecule approaches.