"Suppression of Breast Cancer by Small Molecules That Block the Prolactin Receptor" Borcherding, Dana C.; Hugo, Eric R.; Fox, Sejal R.; Jacobson, Eric M.; Hunt, Brian G.; Merino, Edward J.; Ben-Jonathan, Nira. 2021. Cancers 13, no. 11: 2662.
New paper on the various SMI PRLR inhibitors. They have chosen SMI-6 as their lead candidate.
It was injected at up to 50mg/kg in mice. This equates to 240mg for a 60kg human, but this conversion is just a starting point for calculating human doses.
Breast cancer cell proliferation was stopped with an IC50 from .29uM to 1.33uM, while normal cells were only inhibited at higher concentrations.
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They've also addressed concerns of side effects caused by PRLR inhibition:
Off target effects should be minimal. Importantly for us there was no inhibition of GHR
Effects on PRL+ breast tumor shown below with an infusion of 50 mM SMI-6.
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The bad news is that SMI has PRLR-independent anti-proliferative effects and this could prevent it from being useful for hair growth promotion. Only time will tell.