BioNTech’s breast cancer trial meets its primary endpoint, but benefit is limited; Citi sees manageable impact on the stock

Why is the result disappointing despite meeting the endpoint?

BioNTech and partner DualityBio’s phase III DYNASTY-Breast02 trial of T-pam met its primary endpoint, but the progression-free survival (PFS) benefit was limited and the incidence of interstitial lung disease (ILD) was relatively high among patients with HR-positive, HER2-low metastatic breast cancer, limiting the drug’s potential.
The two companies believe the benefit to patients appears limited. Citi believes further development may require identifying a patient subgroup with a differentiated benefit or obtaining more convincing mature overall survival (OS) data.

Citi noted that before the results were released, investors had gradually recognized the high efficacy bar set by competing drug Enhertu in a similar patient population and lowered their expectations for T-pam.
In the DESTINY-Breast06 trial, median PFS was 13.2 months in the Enhertu group and 8.1 months in the chemotherapy group; the hazard ratio was 0.62, and the objective response rate exceeded 60%. Citi believes that although T-pam’s results were disappointing, they are unlikely to put significant additional downward pressure on BioNTech.

The phase III Fern-EC-01 trial of T-pam for recurrent HER2-expressing endometrial cancer is ongoing. Previously, among patients whose HER2 expression was confirmed by central testing, T-pam’s confirmed response rate was approximately 48%.
This population includes IHC 1+ and 2+ tumors, covering patients outside Enhertu’s tumor-agnostic IHC 3+ label. However, Enhertu is advancing a dedicated phase III endometrial cancer study, and T-pam’s ILD profile remains an important hurdle.

Despite the disappointing breast cancer results, Citi’s positive view of BioNTech remains supported by pumitamig and its broader oncology portfolio. It maintains a Buy, High Risk rating and a 125 dollar price target.
The price target is based on a discounted cash flow model: Citi forecasts free cash flow through 2032, using a weighted average cost of capital of 8.1% and a terminal growth rate of 4.5%. Risks it lists include insufficient evidence of the durability of efficacy across the ADC portfolio and overall survival data from immuno-oncology programs failing to outperform current standard therapies.