Cost-Effectiveness Analysis of Biomarker-Guided Treatment for Metastatic Gastric Cancer in the Second-Line Setting

BACKGROUND

The 5-year survival rate of patients with metastatic gastric cancer (GC) is only 5%. However, trials have demonstrated promising antitumor activity for targeted therapies/immunotherapies among chemorefractory metastatic GC patients. Pembrolizumab has shown particular efficacy among patients with programmed death ligand-1 (PD-L1) expression and high microsatellite instability (MSI-H). The aim of this study was to assess the effectiveness and cost-effectiveness of biomarker-guided second-line GC treatment.

METHODS

We constructed a Markov decision-analytic model using clinical trial data. Our model compared pembrolizumab monotherapy and ramucirumab/paclitaxel combination therapy for all patients and pembrolizumab for patients based on MSI status or PD-L1 expression. Paclitaxel monotherapy and best supportive care for all patients were additional comparators. Costs of drugs, treatment administration, follow-up, and management of adverse events were estimated from a US payer perspective. The primary outcomes were quality-adjusted life years (QALYs) and incremental cost-effectiveness ratios (ICERs) with a willingness-to-pay threshold of $100,000/QALY over 60 months. Secondary outcomes were unadjusted life years (survival) and costs. Deterministic and probabilistic sensitivity analyses were performed to evaluate model uncertainty.

RESULTS

The most effective strategy was pembrolizumab for MSI-H patients and ramucirumab/paclitaxel for all other patients, adding 3.8 months or 2.0 quality-adjusted months compared to paclitaxel. However, this strategy resulted in a prohibitively high ICER of $1,074,620/QALY. The only cost-effective strategy was paclitaxel monotherapy for all patients, with an ICER of $53,705/QALY.

CONCLUSION

Biomarker-based treatments with targeted therapies/immunotherapies for second-line metastatic GC patients substantially improve unadjusted and quality-adjusted survival but are not cost-effective at current drug prices.

Second-line treatment of metastatic gastric cancer in the era of predictive biomarkers: A cost-effectiveness analysis

e15517

Background: Gastric cancer is the third leading cause of cancer-related mortality, with only a 30% five-year survival rate. Patients who progress after one round of systemic therapy face an especially poor prognosis. The National Comprehensive Cancer Network guidelines include both pembrolizumab (PEM) and ramucirumab plus paclitaxel (RAM/PAC) as second-line (2L) therapy for gastric cancer based on data from the Phase II KEYNOTE-059 and Phase III RAINBOW trials, respectively. Recently, the Phase III KEYNOTE-061 trial reported on the effectiveness of PEM for patients with programmed death-ligand 1 (PD-L1) expression and high microsatellite instability (MSI-H). Given the high prices of targeted therapies, it is important to determine if cost-effectiveness is possible using personalized treatment strategies. The aim of this study was to assess the cost-effectiveness of these regimens in both the general patient population and specific biomarker populations. Methods: A decision-analytic (Markov) model was constructed using data from the KEYNOTE-059, KEYNOTE-061, RAINBOW, and REGARD trials. The analysis compared PEM and RAM/PAC for all patients, as well as PEM for patients based on MSI status or PD-L1 expression (combined positive score of 1% or 10%) in the 2L setting. Comparators were paclitaxel monotherapy (PAC) for all patients and best supportive care (BSC) for all patients. Costs (USD) and utility values were estimated from Medicare and the literature. The primary outcome was the incremental cost-effectiveness ratio (ICER) with a willingness-to-pay (WTP) threshold of $100,000. Results: The only cost-effective strategy was PAC monotherapy for all patients, with an ICER of $53,705/QALY. PEM for MSI-H patients and RAM/PAC for microsatellite stable patients was the most effective strategy (greatest QALYs), but was not cost-effective with an ICER of $1,074,620/QALY. Conclusions: Despite their effectiveness, PEM and RAM/PAC are not cost-effective as 2L treatments for metastatic gastric cancer. Although personalizing treatment based on biomarkers improved cost-effectiveness, the ICERs surpassed the WTP threshold at current drug prices.