Background: Drug regulators operate on their own timelines to assess the safety and efficacy of new drugs and/or extensions to existing indications, such that there are delays between regulators. During such a gap, patients in the “early” domain have access to the approved drug, while those in the “late” domain do not, outside of compassionate use. Our study aimed to quantify the “opportunity lost” for new therapies approved by FDA and EMA, assuming patients in the late domain receive standard-of-care (SOC) therapy – which is presumably inferior to the new drug – during the gap. Methods: Anticancer drugs approved by both FDA and EMA were identified through the HemOnc knowledgebase. Inclusion criteria included: 1) drugs approved in both domains based on the same randomized clinical trial (RCTs) for the same indication; 2) a primary time-to-event endpoint; and 3) a quantitated median time-to-event for the primary endpoint. For each included trial, the approval gap between FDA and EMA in days and the ratio of approval gap to median control arm time-to-event duration was calculated. A ratio ≥2 implies that, on average, no late domain patients starting treatment in the first half of the gap would be expected to have access to the new drug prior to an event. Results: Of 60 eligible RCTs, 59 had calculable median event durations. 25 (42%) had a primary overall survival endpoint; the most common surrogate endpoint was progression-free survival (PFS; 29/59; 49%). The median (interquartile range [IQR]) approval gap was 186 (124-271) days, with FDA being the first approver in 56/59 (95%) cases. The median (IQR) ratio of approval gap to median control arm event duration was 0.63 (0.35-1.11). Drugs with ratio ≥2 (Table) were targeted or immunotherapies; 7/8 (88%) were approved with PFS endpoint; 5/8 (62.5%) were approved for second line or later. Conclusions: Our study shows that FDA approves most drugs prior to EMA and a nontrivial number of patients may experience progression or death events while awaiting access to anticancer therapies already approved in another domain. The analysis does not take into consideration scenarios in which the new therapy is inferior to SOC or delays in patient access (due to slow uptake; regulatory barriers [in Europe/UK]; or patient affordability [in US]). Further regulatory collaboration (e.g., Project Orbis) between FDA and EMA could help to reduce and potentially ameliorate this differential in access to new cancer drugs in the future.

¹All drugs except olaparib had FDA approval first.