evalUrsaModel: Evaluate URSA response surface model

In braidrm: Fitting Combined Action with the BRAID Response Surface Model

Evaluate URSA response surface model

Description

Numerically estimates the universal response surface approach (URSA) model for the given data and parameters (Greco, Park, and Rustum 1990).

Usage

evalUrsaModel(DA, DB, upar)

Arguments

DA	A vector of concentrations of drug A in a combination (values 0 and Inf are permitted). Must be length 1 or the same length as DB.
DB	A vector of concentrations of drug B in a combination (values 0 and Inf are permitted). Must be length 1 or the same length as DA.
upar	A length seven URSA response surface parameter vector (see Details)

Details

The URSA model is described by the following seven values

• IDMA: The dose of median effect of drug A, also called the EC50

• IDMB: The dose of median effect of drug B

• na: The Hill slope, or sigmoidicity, of drug A

• nb: The Hill slope of drug B

• alpha: The URSA interaction parameter, indicating additivity (alpha = 0), antagonism (alpha < 0), or synergy (alpha > 0)

• E0: The minimal effect, the effect observed when neither drug is present

• Ef: The maximal effect of the drugs, theoretically observed when either drug is present at infinite concentration

Value

A numeric vector the same length as DA and/or DB with the predicted URSA response surface values.

References

Greco, William R, Hyoung Sook Park, and Youcef M Rustum. 1990. “Application of a New Approach for the Quantitation of Drug Synergism to the Combination of Cis-Diamminedichloroplatinum and 1-b-d-Arabinofuranosylcytosine.” Cancer Research 50 (17): 5318–27.

Examples

concentrations <- c(0, 2^(-3:3))
surface <- data.frame(
    concA = rep(concentrations,each=length(concentrations)),
    concB = rep(concentrations,times=length(concentrations))
)

surface$uadditive <- evalUrsaModel(
    surface$concA,
    surface$concB,
    c(1, 1, 3, 3, 0, 0, 100)
)

surface$usynergy <- evalUrsaModel(
    surface$concA,
    surface$concB,
    c(1, 1, 3, 3, 5, 0, 80)
)

surface$uantagonism <- evalUrsaModel(
    surface$concA,
    surface$concB,
    c(1, 1, 3, 3, -0.5, 0, 100)
)

head(surface)

braidrm documentation built on Sept. 30, 2024, 9:40 a.m.