# Impact of Response Assessment Intervals on Survival and Economic Burden in Long-Term Responders to Immunotherapy for Advanced Non-Small-Cell Lung Cancer

## TL;DR

This study shows that extending the time between check-ups for lung cancer patients on immunotherapy from 2 to 3 months does not harm survival and saves healthcare costs.

## Contribution

The study provides the first statistical evidence that less frequent monitoring is safe and cost-effective for long-term immunotherapy responders.

## Key findings

- Extending response assessment intervals from 2 to 3 months did not significantly affect survival outcomes.
- A 3-month assessment strategy could save nearly USD 6 million annually in the US.
- Patients with positive PD-L1 expression and those on immunotherapy alone had better survival benefits.

## Abstract

Immunotherapy has emerged as a breakthrough for the treatment of advanced non-small-cell lung cancer (NSCLC), significantly improving patient survival. However, it has also led to an increase in the costs associated with response assessment. This study supports that extending the response assessment interval from 2 to 3 months maintains overall survival without compromising advanced NSCLC long-term responders to immunotherapy. This approach using less frequent monitoring may substantially reduce annual healthcare expenditure in the US by nearly USD 6 million.

Background: Immunotherapy has emerged as a breakthrough for the treatment of advanced non-small-cell lung cancer (NSCLC), significantly improving patients’ progression-free survival (PFS) and overall survival (OS). However, the medical burden of response assessment has worsened for long-term maintenance therapy. It remains unclear whether a specific response assessment interval could provide both survival benefits and cost savings. Methods: We retrospectively included patients with advanced NSCLC who underwent immunotherapy and achieved PFS > 12 months. We utilized propensity score matching (PSM) to reduce the selection bias. The survival outcomes were evaluated using the log-rank test and Cox proportional hazard models, while the economic impact was assessed through the performance of a cost minimization analysis (CMA). A medical expenditure extrapolation model was developed based on epidemiological statistics and data from clinical trials. Results: After PSM, a total of 376 patients were included. The survival difference was not significant [hazard ratio (HR) = 0.78, 95% confidence intervals (CIs) = 0.53–1.14; p = 0.200] between the 2-month response assessment group (n = 188) and the 3-month response assessment group (n = 188). Patients receiving immunotherapy alone and those with a positive PD-L1 expression experienced a significant survival benefit. Our extrapolation model projects that, annually, there will be approximately 7026 new long-term responders to immunotherapy in the United States. Adopting a 3-month assessment strategy could reduce annual healthcare expenditure by nearly USD 6 million. Conclusions: This study presented the first statistical evidence supporting a refined response assessment strategy for long-term responders to immunotherapy with advanced NSCLC. These findings support the adoption of a less frequent, yet equally effective, monitoring approach to make tumor surveillance more precise and cost-effective.