PTGER4 and neoplasm: Current early-phase clinical trials testing combinations of anti-PD-(L)1 with specific inhibitors of EP4 alone or EP2 + EP4 in patients with advanced solid tumors (e.g., Clinicaltrials.gov NCT04344795, NCT05205330, NCT05944237) may determine whether anti-tumor and anti-self immunity can be uncoupled using this approach.