CD47 and hematologic disorder: ,16 Moreover, immune-checkpoint-mediated blockage of CD47, a ‘don’t-eat-me’ cell-surface signal for macrophages, has been shown to effectively suppress SCLC tumor growth in vitro and in vivo.17 This is of clinical importance for SCLC as clinical trials targeting CD47 by systemic immunotherapy are already enrolling patients with different solid and hematologic malignancies.18