I just found an article that lends more credibility to the potential of Prolanta (G129R). Here is an excerpt from it that I found to be very intriguing:
"Antagonists Various candidates have been generated by different laboratories, but none has yet entered clinical trials. One of them, namely ?1–9-G129R-hPRL, appears to be promising, as it is the only one displaying both PRL receptor specificity and pure antagonism [6]."