Factors associated with change in the magnitude of clinical benefit of anti-cancer drugs in the post-marketing period.

Abstract

7052 Background: Initial drug approval is often based on surrogate endpoints. Definitive outcomes like Overall Survival (OS) or Quality of life (QoL) may not be available. Here, we evaluate changes in the magnitude of clinical benefit using the American Society of Clinical Oncology Value Framework (ASCO-VF) and European Society for Medical Oncology Magnitude of Clinical Benefit Scale (ESMO-MCBS) comparing the time of approval to the most recent available data for cancer drugs approved by the US Food and Drug Administration (FDA) between 2006 and 2015. Methods: We examined data on trials supporting FDA accelerated (AA) and regular (RA) cancer drug approvals between January 2006 and December 2015. We performed a systematic search of Pubmed and ClinicalTrials.gov to identify updated OS and/or QoL data, with follow up through April 2019. For AA drugs we analysed initial and confirmatory trials as follow-up. ASCO-VF and ESMO-MCBS grades were applied for trials at approval and after marketing. We explored variables associated with improved clinical benefit scores using multivariable logistic regression. Results: We identified 102 trials supporting the approval of 59 drugs for 96 solid tumour indications. Of these indications, 22 (23%) were granted AA and 21 (95%) were converted to RA. At time of approval, 38% of trials showed improved OS and 17% improved QoL. Substantial clinical benefit was observed in 26% of initial approval trials using ESMO-MCSB and in 34% using ASCO-VF. After a median post-marketing period of 3.3 years, updated results changed substantial clinical benefit in 20 trials with ESMO-MCBS (19 upgrades, 1 downgrade) and in 23 trials using ASCO-VF (19 upgrades, 4 downgrades). For 25% of trials no updated information was found. In the palliative setting, multivariable analysis showed association between improved ASCO-VF scores and initial approvals based on single-arm trials (OR 9.21, 95%CI 1.36-62.29, P=0.023), drugs with companion diagnostics (OR 4.95, 95%CI 1.01-24.22, P=0.049) and second or later lines (OR 7.80, 95%CI 1.35-45.02, P=0.022) while for ESMO-MCBS, drugs with companion diagnostics (OR 6.86, 95%CI 1.82-25.86, P=0.004) and immunotherapy drugs (OR 6.42, 95%CI 1.27-32.59, P=0.025) were associated with greater clinical benefit. Conclusions: Drugs with companion diagnostic tests, immunotherapy as well as approved based on single-arm trials were associated with increased clinical benefit after marketing approval. For a quarter of trials there were no updated data in the post-marketing period.