Inflation Reduction Act Impact on Clinical Trial Investment Trends

The Inflation Reduction Act Impact is becoming evident in early data on industry-sponsored clinical trials. A recently published JME article examines how the Drug Price Negotiation Program (DPNP) introduced by the IRA may be altering investment incentives for biopharmaceutical innovation.

Diverging Fortunes: Small Molecules vs Biologics

The most striking findings reveal statistically significant declines in monthly clinical trial starts for small molecule drugs in the 29 months following IRA passage. Pre-approval trials dropped by an estimated 25.2%, while post-approval trials fell by 29.5%. In contrast, biologics showed only modest, non-significant decreases of 2.1% and 13.0% respectively. These patterns provide early descriptive evidence of a potential “pill penalty,” as small molecules become eligible for Medicare Maximum Fair Prices (MFPs) much earlier than biologics.

Clear Evidence of Reduced Trial Activity

For small molecules, the post-IRA period showed a decline of 0.68 trials per month in pre-approval starts (p < 0.05) and 0.22 trials per month in post-approval starts (p < 0.01). Biologics experienced much smaller and statistically non-significant monthly declines. This divergence is particularly notable because biologic trial starts had been growing rapidly before the IRA, while small molecule trends were largely flat.

How the Trends Were Measured

The analysis combined longitudinal clinical trial data with FDA approval information to separate pre-approval from post-approval trials. The study covered January 2010 through December 2024, providing 151 months of pre-IRA data and 29 months of post-IRA data. A linear regression model with interaction terms was used to estimate changes in average monthly Phase I-III industry-sponsored interventional trial starts, applying Newey-West standard errors to address autocorrelation. Multiple robustness checks supported the validity of the findings.

Strategic Implications for HEOR and Market Access

These early signals of reduced small molecule trial activity carry important implications. By shortening the expected period of high revenue generation before potential MFP implementation, the Inflation Reduction Act Impact appears to weaken the investment case for additional indications. This effect is likely to be strongest in therapeutic areas with high Medicare utilization such as oncology and cardiovascular disease.

HEOR professionals should consider these trends when planning evidence generation strategies, as sustained reductions could ultimately affect the availability of new treatment options.