Surrogate markers aid lung cancer trials
medwireNews: Research suggests that surrogate markers for overall survival (OS) are acceptable endpoints for clinical trials of chemotherapy and radiotherapy in patients with lung cancer.
But the best surrogate for a clinical trial will depend on the type of treatment being assessed, say Jean-Pierre Pignon (Gustave Roussy Institute, Villejuif, France) and co-authors.
"We stress that [OS] remains the most valid available endpoint," the team explains in The Lancet Oncology.
"The use of validated surrogates, however, would enable earlier assessments of treatment effects and could lead to conditional approval by regulatory authorities without premature discontinuation of follow-up, which is particularly important to assess the potential for long-term late or toxic effects when a proportion of patients are cured."
The current meta-analysis included data from 60 randomized clinical trials of 15,071 patients that were previously assessed in two meta-analyses of adjuvant chemotherapy in non-small-cell lung cancer, three of sequential or concurrent chemotherapy, and one of radiotherapy in locally advanced lung cancer.
Disease-free survival (DFS) - defined as the time from randomization into the trial to local or distant relapse, or death in patients able to undergo surgery - showed a very good correlation with OS at the individual level for trials of chemotherapy without radiotherapy. DFS also had an excellent correlation with OS at the trial level in chemotherapy studies with or without radiotherapy.
By contrast, in studies of locally advanced disease, progression-free survival (PFS) - defined as time to locoregional or distant relapse or death in patients unable to undergo surgery - showed a very good correlation with OS at the individual level and trial level.
For studies with locoregional control data, there were good individual level correlations and very good trial level correlations for PFS and OS in patients receiving concurrent chemotherapy or modified versus standard radiotherapy regimes.
"[DFS] may be used as a primary endpoint in adjuvant chemotherapy trials involving patients with non-small-cell lung cancers, and [PFS] is suitable for use in trials of chemotherapy and radiotherapy in patients with locally advanced lung cancer," the researchers summarize.
"When [PFS] is substituted for overall [OS], a trade-off is found between earlier results and possible biases in the assessment of progressions," they write.
However, the authors emphasize that their findings cannot be extrapolated to treatments that have substantially different mechanisms of action to conventional chemotherapy or radiotherapy.
"For instance, for targeted agents, surrogate endpoints will need to be studied directly in trials of the agents," they say.
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Lynda Williams, Senior medwireNews Reporter