Don’t stress about CRF: assessing the translational failures of CRF1antagonists

Background Dr. Athina Markou sought treatments for a common neural substrate shared by depression and drug dependence. Antagonists of corticotropin-releasing factor (CRF) receptors, a target of interest to her, have not reached the clinic despite strong preclinical rationale and sustained translational efforts. Methods We explore potential causes for the failure of CRF 1 antagonists and review recent findings concerning CRF-CRF 1 systems in psychopathology. Results Potential causes for negative outcomes include (1) poor safety and efficacy of initial drug candidates due to bad pharmacokinetic and physicochemical properties, (2) specificity problems with preclinical screens, (3) the acute nature of screens vs. late-presenting patients, (4) positive preclinical results limited to certain models and conditions with dynamic CRF-CRF 1 activation not homologous to tested patients, (5) repeated CRF 1 activation-induced plasticity that reduces the importance of ongoing CRF 1 agonist stimulation, and (6) therapeutic silencing which may need to address CRF 2 receptor or CRF-binding protein molecules, constitutive CRF 1 activity, or molecules that influence agonist-independent activity or to target structural regions other than the allosteric site bound by all drug candidates. We describe potential markers of activation towards individualized treatment, human genetic, and functional data that still implicate CRF 1 systems in emotional disturbance, sex differences, and suggestive clinical findings for CRF 1 antagonists in food craving and CRF-driven HPA-axis overactivation. Conclusion The therapeutic scope of selective CRF 1 antagonists now appears narrower than had been hoped. Yet, much remains to be learned about CRF’s role in the neurobiology of dysphoria and addiction and the potential for novel anti-CRF therapies therein.