A series of preclinical studies show that a new compound, SHP1705, targets circadian clock proteins hijacked by glioblastoma stem cells, impairing the cancer cells’ ability to survive and grow. SHP1705 is also the first clock-targeting compound to complete a phase 1 clinical trial, where it was found to be safe and well-tolerated in humans. Glioblastoma is the most common cancerous brain tumor in adults—and one of the most difficult to treat. Most patients receive a combination of surgery, radiation and chemotherapy, but tumors typically return and resist further treatment. Circadian clock proteins, which regulate the body’s sleep-wake cycle and other daily rhythms at the cellular level, offer a potential solution. Glioblastoma cells hijack these proteins in order to replicate, so switching them off could slow or halt tumor growth. Through a series of biochemical, cellular and animal studies, the researchers tested SHP1705’s ability to neutralize glioblastoma stem cells, finding it to be highly effective. A phase 1 clinical trial led by Synchronicity Pharma, a biotechnology startup that Kay co-founded, showed that SHP1705 was well-tolerated in humans.