3S Bio shares surge as partner Pfizer advances bispecific antibody into dual Phase III trials

On October 31, 3S Bio's stock price surged over 10% in early trading to reach HK$30.5.

On October 30, Pfizer registered two global Phase III clinical trials for its PD-1/VEGF bispecific antibody PF-08634404 (SSGJ-707) on ClinicalTrials.gov. The first trial will evaluate the drug in combination with chemotherapy for advanced non-small cell lung cancer (head-to-head against Keytruda + chemotherapy), while the second will assess its use with chemotherapy in metastatic colorectal cancer.

According to publicly available information, in May 2025, Pfizer licensed the PD-1/VEGF bispecific antibody from 3S Bio through a transaction valued at up to $6.05 billion, including a $125 million upfront payment, potential milestone payments of $4.8 billion, and tiered double-digit royalties on sales.

The Phase III clinical trial for first-line treatment of non-small cell lung cancer plans to enroll 1,500 patients, with an estimated primary completion date of February 2029. The study adopts dual primary endpoints of PFS (Progression-Free Survival) and OS (Overall Survival).

The Phase III trial for colorectal cancer aims to enroll 800 patients, with an estimated primary completion date of March 2030. It will conduct a head-to-head comparison against bevacizumab plus chemotherapy, using both OS and PFS as dual primary endpoints