Simulation error in Simbiology

Hi,

I checked the tumor growth model in the library of Simbiology. I noticed if I increase the drug concentration to very high values, the proliferating tumor mass, x1, never goes to zero or negative values. This happens also when I increase the simulation time or the number of RepeatCount . Would you please tell me what part of the model prevents that from happening?

I developed the same model for different type of drug. I have the same solver settings as in the original model found in the library. I checked carefully that everything is the same as much as possible. However, the tumor species, x1, goes to minus values if I increase the simulation time, which doesn't happen with the original model. Therefore, I receive error message and I can't perform the simulation. Does it make sense that it goes to negative values? because for long time, tumor mass is kept taking out in a rate defined by the killing rate and at some point the species will go to negative value. Could you please help in correcting me and clarifying the situation?

Thanks,

Day-light

Answer 1

[Jeremy Huard]

Hi @Day,

can you please share the project file you are using?

Assuming you are using the tumor_growth_fitPKPD_completed.sbproj project shipped with R2023a, I tried to increase the dose amount to 100mg for example and tumor weight goes down to 0 after 35 days. Likewise if I increase the RepeatCount property.

It does not become negative though and should not. If you see negative values on your side, I would recommend to check the solver tolerances and possibly the model equations.

Best regards,

Jérémy