This model is based on the publication:
Coletti R, Leonardelli L, Parolo S, Marchetti L. A QSP model of prostate cancer immunotherapy to identify effective combination therapies. Sci Rep. 2020 Jun 3;10(1):9063. doi: 10.1038/s41598-020-65590-0
Comment:
Eq. 3 - no listed species "R", therefore based ...