Page 206 - EJMO-9-1

Eurasian Journal of Medicine and
Oncology
Cost-effectiveness of nivolumab+chemo for gastric/GEJ cancer

expected value to determine its significant influence A unidirectional sensitivity analysis was conducted to
on decision-making (Table 3). Probabilistic analysis assess the stability of the outputs from the two population
was employed to randomly sample all parameters from models. By altering the input model parameters by ±20%,
specified distributions, further exploring the uncertainty we examined the impact of each parameter on the analysis
and relevance of the model’s parameters. Based on the type results. The outcomes are depicted in a tornado diagram
of parameter, appropriate distributions were selected: the (Figure 2). The sensitivity analysis indicated that the cost
costs associated with AEs and treatments followed a gamma of nivolumab had the greatest contribution.
distribution, while the risk of AEs and health utility scores
– including PFS, OS, and AE – followed a beta distribution. 3.3. Probability sensitivity analysis
A second-order Monte Carlo simulation with 10,000 Probabilistic sensitivity analysis was employed to evaluate
iterations generated a cost-effectiveness acceptability curve the bias of multiple model parameters on the analysis
demonstrating that nivolumab plus chemotherapy is cost- outcomes when the parameters change concurrently.
effective at different WTP thresholds. The results are illustrated through cost-effectiveness
acceptability curves (Figure 3) and incremental cost-
3. Results effectiveness scatterplots (Figure 4). Based on the
3.1. Base-case analysis findings, we discovered that a higher average societal
WTP correlates with an increased likelihood of
The result of the base-case analysis regarding the cost nivolumab plus chemotherapy being cost-effective. With
and effectiveness of nivolumab plus chemotherapy a payment threshold of $207,659 per QALY, probabilistic
group compared to the chemotherapy group in patients sensitivity analysis indicated a 1.49% probability that
with untreated and unresectable advanced or metastatic nivolumab plus chemotherapy would be cost-effective
G/GEJ/esophageal adenocarcinoma are presented in within the fluctuation range of other model parameters
Table 1. According to our analysis, the incremental cost of for first-line treatment in advanced G/GEJ/esophageal
nivolumab plus chemotherapy ($149,636.97, 1.24 QALYs) adenocarcinoma.
versus chemotherapy alone ($13,941.06, 0.75 QALYs) is
$135,695.91, resulting in a difference of 0.49 QALYs. The We also performed a subgroup analysis of patients with
ICER value of $276,799.67 is higher than the US’s triple PD-L1 CPS ≥5 based on median age (IQR), race (Asian
GDP per capita threshold in 2021 ($207,659). or non-Asian), region (Asia, US and Canada, or rest of
world), primary tumor location at initial diagnosis (G or
3.2. Sensitivity analyses GEJ or esophageal adenocarcinoma), tumor cell PD-L1
expression levels, Eastern Cooperative Oncology Group
performance status (0 or 1), prior surgery (yes or no),
Table 3. Model parameters of log‑logistic survival model the number of organs with metastases, presence of signet
ring cell carcinoma (yes or no), Lauren classification
Variable Baseline value (intestinal type, diffuse type, mixed or unknown),
Log-logistic survival model in nivolumab plus Shape Scale microsatellite instability status (microsatellite stable,
chemotherapy group
microsatellite instability-high, not reported, or invalid),
PFS 1.648147 8.546154 chemotherapy regimen (FOLFOX or XELOX), disease
OS 1.6508 14.4888 stage (metastatic, locally advanced or locally recurrent),
Log-logistic survival model in the chemotherapy and site of metastases (liver, peritoneum, or central
group nervous system), according to the survival of subgroups
PFS 1.6508 14.4888 of patients in CheckMate 649. Unfortunately, none of the
OS 1.7398 10.546 subgroup analysis factors were likely cost-effective when
Abbreviations: OS: Overall survival; PFS: Progression-free survival. the payment threshold was less than or equal to $207,659
per QALY.
4. Discussion

Fluoropyrimidine plus platinum-based chemotherapy
is the first-line treatment for unresectable advanced or
metastatic HER2-negative G/GEJ adenocarcinoma, but its
efficacy is poor. The subjects included in the CheckMate
649 trial were patients with advanced or metastatic G/GEJ/
Figure 1. Markov state transition model esophageal adenocarcinoma who tested negative for HER2.

Volume 9 Issue 1 (2025) 198 doi: 10.36922/ejmo.7075