Pfizer has joined the PD-1xVEGF bispecific gold rush. The Big Pharma is paying 3SBio $1.25 billion upfront for ex-China rights to a clinical candidate, establishing itself as a challenger to BioNTech, Merck & Co. and Summit Therapeutics in a scorching-hot area of immuno-oncology.
Interest in PD-1/L1xVEGF bispecifics has been high since Summit and Akeso’s ivonescimab beat Merck’s megablockbuster Keytruda in a head-to-head trial. Since then, Merck has paid $588 million to join the race and BioNTech has handed over $800 million to secure full rights to a candidate it previously picked up through an ex-China deal.
Pfizer made a splashy entrance late Monday, revealing it is paying $1.25 billion upfront and committing up to $4.8 billion in milestones for ex-China rights to 3SBio’s SSGJ-707. Pfizer is investing $100 million in 3SBio and will pay tiered double-digit royalties on sales of SSGJ-707, if approved.
The deal gives Pfizer rights to a bispecific that is set to enter phase 3 in China, 3SBio’s home market, this year. 3SBio began four phase 2 trials of SSGJ-707 last year to assess the bispecific in colorectal, ovarian and non-small cell lung cancers (NSCLC). All the sites used in the studies are in China, according to the listings on ClinicalTrials.gov. The first phase 3 trial will enroll first-line, PD-L1 positive NSCLC patients.
3SBio shared (PDF) data from the phase 2 trials in January. The biotech reported a 70.8% response rate in first-line, PD-L1-positive NSCLC patients. Combined with chemotherapy, SSGJ-707 achieved response rates of up to 81.3% in another population of first-line NSCLC patients. 3SBio reported a 33.3% response rate in third-line colorectal cancer patients, a population in which it said rivals were yet to show promise.
Pfizer signaled its interest in PD-1/L1xVEGF bispecifics in February. That month, Pfizer inked a deal to test its antibody-drug conjugates with Summit and Akeso’s ivonescimab. Days later, Megan O'Meara, M.D., head of early clinical development in oncology at Pfizer, called (PDF) PD-1xVEGF a “very interesting” combination of targets and said the company was following the space “very closely.”
Securing ex-China rights to SSGJ-707 slots Pfizer in behind Summit and BioNTech in the race for the U.S. market. Summit is leading the way, with results from its first phase 3 study due mid-2025, and BioNTech started a phase 2/3 trial of its contender in January. LaNova Medicines, the originator of Merck’s asset, began a phase 1/2 trial in Australia and China in October. 3SBio said it has an approved IND for SSGJ-707.
Pfizer’s big bet on SSGJ-707 represents a show of faith in a mechanism that suffered a setback last month when Akeso revealed ivonescimab failed to significantly reduce the risk of death compared to Keytruda at an interim NSCLC analysis. The news crashed Summit’s share price. Whether PD-1/L1xVEGF bispecifics can beat Keytruda on overall survival in Western trials is the big outstanding question facing the field.