If real pharmacokinetic (PK) data from this study show difference from mg/kg assumption, the nivolumab prio r will be revisited and modified accordingly. 4.1.3 Marginal Prior Derivation for Ipilimumab Parameters (log( αα3), log(β3)) Similar to BMS-986226 monotherapy in the monotherapy phase, the logistic model for ipilimumab is as follows: ݐ݅݃݋݈൫ݍ௝൯ൌ݃݋݈ ሺߙଷሻ൅ߚଷ݃݋݈ሺ݀ଷ௝ ݀ଷ∗൘ሻ, where ݍ௝is the probability of toxicity at dose level ݀ଷ௝. Note that the α3 and β3 parameters are assumed positive, and ݀ଷ∗is the reference dose for ipilimumab. Since DLT information from ipilimumab studies was not available, incidence of treatment-related Grade 3 to 4 adverse events (AEs) from various Phase 2 to 3 ipilimumab studies at Bristol-Myers Squibb (BMS) in participants with pre viously treated or untreated advanced melanoma was used in lieu of DLT rate in order to derive the prior for the BLRM parameters corresponding to the effect of ipilimumab, (log( α 3), log(β3)). Specifically, a bivariate normal MAP prior for the ipilimumab model parameters (log( α3), log(β3)) was obtained by extracting a posterior of ipilimumab using DLT and safety data from Phase 2 and 3 ipilimumab studies in BMS and the meta-analytical-pre dictive approach. Finally, a mixture prior with both MAP and weakly informative components will be generated for BLRM parameters of ipilimumab. The MAP prior for the model parameters (log( α3), log(β3)) was obtained in the following steps. First, a weakly informative prior for ipilimumab was developed: •The median toxicity rate at the ipilimumab refe rence dose (10 mg/kg every 3 weeks) was assumed to be 30%, ie, mean (log( α 3)) = logit(0.30)= -0.847. •A doubling in dose was assumed to double the odds of DLT, ie, mean (log( β3)) = 0.