PHGDH and cancer: Encouragingly, previous in vivo mouse experiments with PHGDH inhibitors demonstrated a tolerable toxicity profile with neither weight loss nor abnormal behaviour.51–53 Therefore, further in vivo animal studies on neurological side effects as well as clinical trials on the efficacy and safety of the combination of serine/glycine deprivation with inhibition of the SSP, especially of PHGDH, are exciting future options for a serine-targeted therapeutic approach in cancer.