Overall survival benefits of cancer drugs initially approved by the US Food and Drug Administration on the basis of immature survival data: a retrospective analysis

Abstract

Background: New cancer drugs can be approved by the US Food and Drug Administration (FDA) on the basis of surrogate endpoints while data on overall survival are still incomplete or immature, with too few deaths for meaningful analysis. We aimed to evaluate whether clinical trials with immature survival data generated evidence of overall survival benefit during the period after marketing authorisation, and where that evidence was reported.

Methods: In this retrospective analysis, we searched Drugs@FDA to identify cancer drug indications approved between Jan 1, 2001, and Dec 31, 2018, on the basis of immature survival data. We systematically collected publicly available data on postapproval overall survival results in labelling (Drugs@FDA), journal publications (MEDLINE via PubMed), and clinical trial registries (ClinicalTrials.gov). The primary outcome was availability of statistically significant overall survival benefits during the period after marketing authorisation (until March 31, 2023). Additionally, we evaluated the availability and timing of overall survival findings in labelling, journal publications, and ClinicalTrials.gov records.

Findings: During the study period, the FDA granted marketing authorisation to 223 cancer drug indications, 95 of which had overall survival as an endpoint. 39 (41%) of these 95 indications had immature survival data. After a minimum of 4·3 years of follow-up during the period after marketing authorisation (and median 8·2 years [IQR 5·3-12·0] since FDA approval), additional survival data from the pivotal trials became available in either revised labelling or publications, or both, for 38 (97%) of 39 indications. Additional data on overall survival showed a statistically significant benefit in 12 (32%) of 38 indications, whereas mature data yielded statistically non-significant overall survival findings for 24 (63%) indications. Statistically significant evidence of overall survival benefit was reported in either labelling or publications a median of 1·5 years (IQR 0·8-2·3) after initial approval. The median time to availability of statistically non-significant overall survival results was 3·3 years (2·2-4·5). The availability of overall survival results on ClinicalTrials.gov varied considerably.

Interpretation: Fewer than a third of indications approved with immature survival data showed a statistically significant overall survival benefit after approval. Notable inconsistencies in timing and availability of information after approval across different sources emphasise the need for better reporting standards.

Funding: None.