The late-stage phase III trial displayed an improvement in progression-free survival when assessed against standard chemotherapy for patients with non-small cell lung cancer who had prior treatments. Despite this, investors expressed concerns with the effectiveness of the drug, as "clinically meaningful" results were absent from the report. This led to a drop of 8% in AstraZeneca's shares Jul. 3, the lowest they've seen since March and a drop of 4% in Daiichi Sankyo's shares.

Susan Galbraith, executive vice president, oncology R&D at AstraZeneca, said: “These first Phase III trial results from the datopotamab deruxtecan clinical program provide compelling evidence for the potential role this (antibody) can play in treating patients with lung cancer.” And Ken Taeshita, global head of oncology R&D at Daiichi Sankyo said that he "look(s) forward to the final overall survival analysis."

Dato-DXd plays a crucial role in both companies' pipelines, and while the results show promise, they don't quite hit the mark when it comes to investor expectations.