Cost-effectiveness analysis of pembrolizumab plus trastuzumab and chemotherapy as first-line treatment for HER2-positive gastric or gastroesophageal junction adenocarcinoma.

OBJECTIVES

The final analysis of KEYNOTE-811 demonstrated that pembrolizumab plus trastuzumab and chemotherapy significantly improved both overall survival (OS) and progression-free survival (PFS) compared to trastuzumab plus chemotherapy alone. Based on these latest findings, this study evaluated the cost-effectiveness of pembrolizumab plus trastuzumab and chemotherapy from the perspective of the Chinese healthcare system.​.

DESIGN

Using a partitioned survival model, this study compared quality-adjusted life years (QALYs), total costs, and incremental cost-effectiveness ratios (ICERs) between pembrolizumab plus trastuzumab and chemotherapy versus trastuzumab plus chemotherapy alone. Efficacy and safety data were derived from KEYNOTE-811, local databases, and relevant literature. To validate the robustness of the model results, sensitivity analyses were conducted. Additionally, subgroup analyses were conducted specifically for the patient population with PD-L1 expression ≥1%.​.

INTERVENTIONS: Pembrolizumab plus trastuzumab and chemotherapy.

OUTCOME MEASURES: Total costs, life years, quality adjusted life years (QALYs), incremental QALYs and incremental cost-effectiveness ratio (ICER).

RESULTS

In the intention-to-treat (ITT) population, pembrolizumab plus trastuzumab and chemotherapy demonstrated a gain of 0.56 QALYs compared to trastuzumab plus chemotherapy alone, with an additional cost of $322,653.47, resulting in an ICER of $571,997.42/QALY. In the PD-L1 ≥ 1 subgroup, the pembrolizumab combination arm showed a QALY improvement of 0.38, yielding an ICER of $1,178,714.74 per QALY.​.

CONCLUSION

From the perspective of Chinese healthcare system, the addition of pembrolizumab to trastuzumab-chemotherapy as first-line therapy failed to demonstrate cost-effectiveness for HER2-positive gastric/gastroesophageal junction adenocarcinoma across both the ITT population and PD-L1 ≥ 1 subgroup.