Earlier in April, doctors at the National Institutes of Health made a promising step in the fight against cancer, announcing an immunotherapy treatment was able to shrink gastrointestinal tumors for about a quarter of patients. But NIH staffing shortages, layoffs and cuts are threatening to delay the rollout of this promising development. William Brangham speaks with Dr. Steven Rosenberg for more. PBS News is supported by - https://www.pbs.org/newshour/about/funders