BioNTech SE (BNTX) and DualityBiologics (Suzhou) Co., Ltd. said Monday that their Phase 3 DYNASTY-Breast02 trial met its primary endpoint. That sounds like a clean win. It is not quite that simple.

The drugmakers were quick to add that the treatment offers limited potential benefit in the metastatic breast cancer landscape. In other words, the trial checked the box, but the box was not especially large.

Modest Survival Gains in Phase 3 Trial

The study pitted trastuzumab pamirtecan against physician-selected chemotherapy in chemotherapy-naïve patients with HR+/HER2-low metastatic breast cancer following endocrine therapy.

The treatment achieved a statistically significant, yet modest improvement in progression-free survival. Meanwhile, overall survival data remained immature during this interim analysis, so the longer-term picture is still developing.

Safety Findings Show Increased Lung Risks

Investigators documented a higher rate of interstitial lung disease compared to earlier studies of trastuzumab pamirtecan. Most incidents presented as Grade 1 and 2 cases, but a small percentage of patients suffered severe and fatal Grade 3 to 5 events.

The therapy otherwise maintained an overall safety profile consistent with earlier trials, with no new safety signals emerging.

Companies Weigh Strategic Next Steps

BioNTech and DualityBio will evaluate the clinical data to determine their upcoming plans. Beyond this study, the two drug developers are testing trastuzumab pamirtecan across two additional programs: a Phase 3 study in HER2-expressing recurrent endometrial cancer and a Phase 1/2 trial in advanced solid tumors.

This is not the only recent data point for BioNTech. In October, the company reported initial findings from the AHEAD-MERIT Phase 2/3 trial assessing BNT113, an investigational mRNA cancer immunotherapy.

That study evaluates BNT113 paired with Merck & Co. Inc.'s (MRK) Keytruda (pembrolizumab) versus pembrolizumab alone as an initial treatment for patients suffering from advanced head and neck cancer.

During the initial analysis, the combination of BioNTech's BNT113 and pembrolizumab did not achieve a statistically significant improvement in progression-free survival when compared directly to the pembrolizumab monotherapy.

BNTX Price Action: BioNTech shares were trading 2.57% lower at $85.85 during premarket trading on Monday, according to market data.