On June 6, 2023, Zai Lab reported phase 3 trials for an oncology therapy it is developing with NovoCure. It said that its tumor treating fields (TTFields) therapy, which uses skin patches to deliver electric fields to areas of the body, when used with standard therapies, met its primary endpoint of three-month improvement in median overall survival time in metastatic non-small cell lung cancer (NSCLC) patients. Further, the company reported that patients with the TTFields therapy has a median overall survival time of 13.2 months compared to 9.9 months with patients who just had standard therapies. However, many of the study participants didn’t use an initial checkpoint inhibitor, which is seen as the leading way to treat NSCLC, thereby allowing for the possibility that the study was highly skewed by comparing TTFields to a lesser therapy.
On this news, Zai Lab’s stock fell $4.88 per share, or 14.55%, on unusually high trading volume, to close at $28.66 per share on June 7, 2023.