Corbus Pharmaceuticals is mounting a David vs. Goliath battle against Seagen, spending $7.5 million of its dwindling cash reserves on a challenger to the nectin-4 antibody-drug conjugate (ADC) Padcev.
Analysts expect Padcev, which came to market in the U.S. in 2019, to emerge as a favored treatment for urothelial cancer in the coming years and to generate blockbuster sales for Seagen. But Corbus sees the safety of Padcev—and its impact on tolerability and dose intensity—as a weakness that creates room for a challenger, leading it to strike a deal to join the small shoal of biotechs chasing Seagen.
Corbus has picked up regional rights to a would-be rival to Padcev through a deal with CSPC Megalith Biopharmaceutical. The Chinese drug developer has sold the rights to its anti-nectin-4 ADC in Australia, Europe and North America to Corbus for $7.5 million upfront and up to $685 million in milestones. Most, $555 million, of the contingent fees are tied to commercial events, with the rest linked to development and regulatory successes.
CSPC is running a phase 1 dose-escalation clinical trial of the candidate in advanced solid tumor patients in China and has received regulatory clearance to start a study in the U.S. Corbus plans to leverage data from the Chinese study to support the start of the U.S. clinical trial of CRB-701 next year.
The development timeline means Corbus has ceded a big head start to both Seagen and its main rival for the nectin-4 space, Bicycle Therapeutics. Bicycle moved its challenger into phase 1 in July 2020. Even so, Corbus thinks CRB-701 has the credentials to make a mark.
“CRB-701 has several key features that support a differentiated profile,” Rachael Brake, Ph.D., chief scientific officer at Corbus, explained in a release. “These include site-specific conjugation chemistry that leads to low payload release in plasma, a novel Fc-enabled antibody with an improved pharmacokinetic profile and toxicology data that suggests that there is an ability to achieve higher exposures with CRB-701.”
Those attributes have persuaded Corbus to write CSPC a check despite its current cash constraints. Late last year, the biotech told investors it had the cash to keep going through the second quarter of 2024. By cutting back in other areas and focusing its cash on CRB-701, Corbus has kept that runway target even after the outlay on the new program.