Pfizer looks for Tukysa maintenance

Of the drugs that Pfizer gained through its $43bn acquisition of Seagen in 2023 the small-molecule HER2 inhibitor Tukysa isn’t the biggest, but the group is still eyeing expansion. On Tuesday the company toplined a win in the Her2climb-05 trial, testing Tukysa plus Roche’s Herceptin and Perjeta as first-line maintenance in HER2-positive breast cancer. Pfizer claimed a statistically significant and “clinically meaningful” improvement with the triplet versus Herceptin plus Perjeta alone, but is saving details for a future medical conference. Since Tukysa was approved in 2020, for HER2-positive breast cancer patients who had previously received an anti-HER2-based regimen, Daiichi Sankyo/AstraZeneca's ADC Enhertu has emerged as the top dog in the HER2 space. Enhertu is now FDA approved in second-line HER2-low and ultralow patients, and the partners are also eyeing earlier uses. In the front line, the Destiny-Breast09 trial recently reported a 44% reduction in the risk of progression or death with Enhertu plus Perjeta, versus Perjeta plus Herceptin and chemo. This could provide a bar for Tukysa to clear, although Destiny-Breast09 isn’t a maintenance trial, so isn’t strictly comparable. Sales figures tell a clearer story, though: Tukysa sold $480m in 2024, compared with Enhertu’s $3.8bn.

Notable Tukysa trials in HER2+ve breast cancer

Source: OncologyPipeline.