Description
The figure shown below shows a cost-effectiveness plane produced using a Cohort State Transition Model (CSTM) to simulate drug costs and QALYs for three interventions (serplulimab, atezolizumab, and durvalumab) in combination with the standard of care (carboplatin and etoposide) compared to chemotherapy alone to treat extensive-stage small cell cancer. Simulations were run to improve the statistical significance of the trial outcomes which were limited to <300 subjects per treatment group. Probabilistic sensitivity analysis was not conducted, because the disease model for ES-SCLC is too limited since the patient population faces high mortality a certain time after treatment and their outcomes are mostly unidirectional. Patients who underwent remission and second-line treatments within the overall survival window observed in the trials were not accounted for, however these can be integrated into the model (it becomes a dynamic model). TWTP thresholds were set at (1) $300,000, (2) $150,000, and (3) $50,000 per QALY.
Methodology
As previously mentioned, the disease was modeled using a CSTM because of the 30,000 simulations and progression from PFS to OS that is a trade-off point when accounting for drug costs. This model takes the perspective that the patients are treated solely in a hospital-based setting in the United States. The placeholder price of serplulimab was $10,000 per dose, while the others were based on their ASP. This was to emphasize that even at a lower price, cost-effectiveness is in question. Costs used were based on the treatment of a lung neoplasm with major complications and comorbidities because of the patient characteristics of the studies and relatively short OS.
Insights
- The cost of cancer care is high, but the quality-of-life is slightly higher when treated with the three interventions compared to chemotherapy
- Serplulimab is the most cost-effectiveness of the three interventions (~40% of simulations vs. ~35% atezolizumab vs. <10% durvalumab) when using WTP Threshold 2
- Durvalumab did not do well in this model, because of the clincial outcomes from the CASPIAN trial
- These drugs will need to have significant rebates (payers) or discounts (hospitals) to be cost-effective and can be further investiated
- Changing to a dynamic model does not significantly improve cost-effectiveness in this case, but modifying it to include the contribution from government programs improves cost-effectiveness
References
IMPOWER133, CASPAIN, ASTRUM-005, FDA, CMS