Radiation oncologist here, the radiation dose delivered (32Gy whole brain in 1.6Gy BID) with boost to tumors is highly unusual and outdated. It causes short term memory loss at a higher rate than stereotactic radiosurgery - which is the preferred standard of care for unresectable BM if the disease is limited.

Stereotactic radiosurgery regularly achieves control rates >70% without any radiosensitizers.

That said, solid work, and bravo if L-Arginine works. Next most obvious work would be to test in stereotactic radiosurgery.