Cullinan Therapeutics was impressed enough with Harbour BioMed’s bispecific immune activator that it handed over $25 million last year for the drug's U.S. rights. But, having taken a peek at phase 1 data, Cullinan has had second thoughts.
The asset, dubbed CLN-418, has been touted as the only bispecific under development targeting antigens B7H4 and 4-1BB, which is hypothesized to better stimulate T cells and limit tumor growth all while improving toxicity. Harbour BioMed has said in the past that it believes the candidate is a “promising” option for patients who are PD-L1-negative and/or those who are resistant to PD-L1-targeting treatments.
A phase 1 solid tumor trial for the drug kicked off in March 2022. When the two companies signed the licensing deal in February 2023—which also included up to $550 million in biobucks that could have come Harbour’s way—Cullinan said that CLN-418 was a “strong strategic fit … building on our expertise with bispecifics, and placing us at the forefront of bispecific antibody development in solid tumors.”
Now, the verdict is in from that trial, and it doesn’t sound great. In this morning’s second-quarter earnings, the biotech said that “following a review of the data from the phase 1 study” it now plans to discontinue development.
It means Harbour BioMed will get back the full rights to CLN-418 but lose the chance to cash in on those $550 million in milestone payments.
In this morning’s release, Cullinan CEO Nadim Ahmed cited the move as a way to “focus our resources on our most promising programs."
Top of Ahmed’s list is CLN-978, a CD19xCD3 T cell engager Cullinan plans to launch in a global study in systemic lupus erythematosus this year as part of the biotech’s expansion into autoimmune diseases.
“We are committed to exploring the broad potential of CLN-978 across autoimmune diseases and will pursue rheumatoid arthritis (RA) as our next indication, where there is both significant unmet patient need and clinical validation for CD19 T cell engagers,” the CEO explained in the release.
“We are excited to collaborate with FAU Erlangen-Nuremberg and Università Cattolica del Sacro Cuore, Rome to conduct a clinical trial of CLN-978 in patients with RA,” Ahmed added. “Both are pioneering centers of excellence in the field of T cell redirecting therapies for autoimmune diseases and the first to demonstrate the potential of a CD19 T cell engager in RA.”