select_boin12_obd {escalation}

Select dose by BOIN12's OBD-choosing algorithm.

Description

This method selects dose by the algorithm for identifying the optimal biological dose (OBD) described in Lin et al. (2020). This class is intended to be used when a BOIN12 trial has reached its maximum sample size. Thus, it intends to make the final dose recommendation after the regular BOIN12 dose selection algorithm, as implemented by get_boin12, has gracefully concluded a dose-finding trial. However, the class can be used in any scenario where there is a limit toxicity rate. See Examples. Note - this class will not override the parent dose selector when the parent is advocating no dose. Thus this class will not reinstate a dangerous dose.

Usage

select_boin12_obd(
  parent_selector_factory,
  when = c("finally", "always"),
  tox_limit = NULL,
  ...
)

Arguments

parent_selector_factory

Object of type selector_factory.

when

Either of: 'finally' to select dose only when the parent dose-selector has finished, by returning continue() == FALSE; or 'always' to use this dose-selection algorithm for every dose decision. As per the authors' original intentions, the default is 'finally'.

tox_limit

We seek a dose with toxicity probability no greater than. If not provided, the value will be sought from the parent dose-selector.

...

Extra args are ignored.

Value

an object of type selector_factory.

References

Lin, R., Zhou, Y., Yan, F., Li, D., & Yuan, Y. (2020). BOIN12: Bayesian optimal interval phase I/II trial design for utility-based dose finding in immunotherapy and targeted therapies. JCO precision oncology, 4, 1393-1402.

Examples

# This class is intended to make the final dose selection in a BOIN12 trial:
tox_limit <- 0.35
model <- get_boin12(num_doses = 5, phi_t = 0.35, phi_e = 0.25,
                    u2 = 40, u3 = 60, n_star = 6) %>%
  stop_at_n(n = 12) %>%
  select_boin12_obd()

outcomes <- '1NNN 2NTN 2NNN 3NTT'
model %>% fit(outcomes) %>% recommended_dose()

# However, since behaviour is modular in this package, we can use this method
# to select dose at every dose decision:
model2 <- get_boin12(num_doses = 5, phi_t = 0.35, phi_e = 0.25,
                    u2 = 40, u3 = 60, n_star = 6) %>%
  select_boin12_obd(when = 'always')
model2 %>% fit('1NNT') %>% recommended_dose()
model2 %>% fit('1NNN 2NNT') %>% recommended_dose()