Subsequent Indications in Oncology Drugs: Pathways, Timelines, and the Inflation Reduction Act.

Introduction: Recent research has raised questions about potential unintended consequences of the Inflation Reduction Act's Drug Price Negotiation Program (DPNP), suggesting that the timelines introduced by the law may reduce manufacturer incentives to invest in post-approval research towards additional indications. Given the role of multiple indications in expanding treatment options in patients with cancer, IRA-related changes to development incentives are especially relevant in oncology. This study aimed to describe heterogeneous drug-level trajectories and timelines of subsequent indications in a cohort of recently approved, multi-indication oncology drugs, including overall, across subgroups of drugs characterized by the timing and pace of additional indications, and by drug type (i.e., small molecule vs. biologic).

Methods: This cross-sectional study evaluated oncology drugs first approved by the FDA from 2008 to 2018 and later approved for one or more additional indications. Numbers, types, and approval timelines of subsequent indications were recorded at the drug level, with drugs grouped by quartile based on the pacing of post-approval development (i.e., "rapid pace" to "measured pace").

Results: Multi-indication oncology drugs (N = 56/86, 65.1%) had one or more subsequent indication approved in a new: cancer type (60.7%), line of treatment (50.0%), combination (41.1%), mutation (32.1%), or stage (28.6%). The median time between FDA approvals for indications increased from 0.6 years (IQR: 0.48, 0.74) in the "rapid pace" group to 1.6 years (IQR: 1.32, 1.66), 2.4 years (IQR: 2.29, 2.61), and 4.9 years (IQR: 3.43, 6.23) in the "moderate," "measured-moderate," and "measured" pace groups, respectively. Drugs in the "rapid pace" group often received their first subsequent indication approval within 9 months of initial approval (median: 0.7 years; IQR: 0.54, 1.59), whereas the "measured pace" group took a median of 5.7 years (IQR: 3.43, 6.98). Across all multi-indication drugs, the median time to the most recent approval for a subsequent indication was 5.5 years (IQR: 3.18, 7.95). One quarter (25%) of drugs were approved for their most recent subsequent indication after the time at which they would be DPNP-eligible.

Conclusion: Approval histories of new oncology drugs demonstrate the role of post-approval indications in expanding treatment options towards new cancer types, stages, lines, combinations, and mutations. Heterogeneous clinical development pathways provide insights into potential unintended consequences of IRA-related changes surrounding post-approval research and development.