To investigate why checkpoint inhibitors so often stop working, Velculescu; Valsamo Anagnostou, M.D., Ph.D., instructor of
oncology at the Johns Hopkins University School of Medicine; Kellie N. Smith, Ph.D., a cancer immunology
research associate at the Johns Hopkins University School of Medicine; and their colleagues at the Bloomberg ~ Kimmel Institute for Cancer Immunotherapy studied tumors of four patients with non-small cell lung cancer and one patient with head and
neck cancer who developed resistance to two different checkpoint inhibitors: a drug called nivolumab that uses an antibody called anti-PD-1, or nivolumab used alone or in combination with a second drug called ipilimumab, which uses an antibody called anti-CTLA4.