CT-38 is either very similar to, or identical to the (also 38 amino acid peptide) urocortin II.
Whether a ligand is considered an agonist or antagonist depends on the (competitive) receptor binding kinetics compared to the endogenous ligands.
It is highly likely that CT-38 is a CRF2 receptor agonist. It is true that receptors can be desensitised due to too much activity/"signal" by agonists. For example, the most common reason for the 5-HT1A receptor desensitisation noted in a variety of patient groups is antidepressant use! This desensitisation can persist over time too.
Just keep in mind, this is an agonist, not an antagonist.
This is the hypothesis f
or the "Model-Based Therapeutic Correction of Hypothalamic-Pituitary-Adrenal Axis Dysfunction" by Amos Ben-Zvi, Suzanne D. Vernon, Gordon Broderick in 2009
http://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1000273
The problem with that model is it doesn't match the reality of what has been found in ME patients so far. But it is still an interesting paper worth publishing.
I don't believe that this CT-38 trial will be successful, due to it being based on flawed science. But I still believe the trial should go ahead, least of which to show that the research community still has the capacity to do clinical trials.