RE:Conventional triple negative BC drug long term side effectsIn 2021 Pfizer for the first time talked up its own PD-(L)1 challenger, sasanlimab.
Pfizer returned the anti-PD-L1 Bavencio to Merck KGaA in 2023, which it originally licensed in 2014. Interestingly, sasanlimab was also included in that 2014 deal: Pfizer says the molecule had been originated in house, but the two companies agreed to work together on it, before Pfizer regained rights in December 2018, according to US SEC filings.
https://www.evaluate.com/vantage/articles/news/corporate-strategy/pfizer-reveals-its-pd-1-secret