Here we report: (1) clinical safety, preliminary activity, and pharmacokinetics of GS‐0189 as monotherapy and in combination with rituximab from a phase 1 clinical trial in patients with relapsed/refractory NHL (NCT04502706, SRP001); (2) in vitro characterization of GS‐0189 binding to SIRPα; and (3) in vitro phagocytic activity. This evidence concerns the gene SIRPA and non-Hodgkin lymphoma.