Bayer has pulled out of a $670 million partnership it entered into in December 2020 with South San Francisco, Calif.-based Atara Biotherapeutics for the company’s investigational T-cell therapies.

The collaboration included ATA3271, an allogeneic T-cell immunotherapy, and an autologous version, ATA2271, for high mesothelin-expressing tumors such as malignant pleural mesothelioma and non-small cell lung cancer.

The ending of the partnership follows the death of a patient in an early-phase clinical trial of ATA2271 at Memorial Sloan Kettering Cancer Center in February.

Atara said it still believes in the potential of its ATA2271 treatment, along with the company’s investigational armored allogeneic T-cell immunotherapy, ATA3271, for treatment of solid tumors.