An AstraZeneca Plc cancer medicine showed a statistically significant improvement over standard chemotherapy in a high-level study.

The drug helped patients with the most common form of lung cancer live longer without worsening compared with standard chemotherapy, the UK drugmaker said Monday. AstraZeneca didn’t say how much longer patients lived overall and the trial is continuing because the data isn’t fully mature yet.

The results potentially validate Astra’s decision to pay as much as $6 billion for the right to develop the medicine with Daiichi Sankyo Co. and its bet to revive growth a decade ago by building a pipeline of oncology drugs. The treatment could garner as much as $18 billion in sales, according to Jefferies analysts.

Scientists and doctors have been trying to find a more targeted approach to chemotherapy for decades in an effort to move away from the current catch-all method that involves blasting the whole body and killing good cells as well as bad. Astra’s drug - known as datopotamab deruxtecan, or Dato-DXd - takes a more potent chemo directly to the infected cells to kill the cancer while sparing the healthy cells.