Pathological response after neoadjuvant chemotherapy in resectable non-small-cell lung cancers: proposal for the use of major pathological response as a surrogate endpoint.

Improvements in outcomes for patients with resectable lung cancers have plateaued. Clinical trials of resectable non-small-cell lung cancers with overall survival as the primary endpoint require a decade or longer to complete, are expensive, and limit innovation. A surrogate for survival, such as pathological response to neoadjuvant chemotherapy, has the potential to improve the efficiency of trials and expedite advances. 10% or less residual viable tumour after neoadjuvant chemotherapy, termed here major pathological response, meets criteria for a surrogate; major pathological response strongly associates with improved survival, is reflective of treatment effect, and captures the magnitude of the treatment benefit on survival. We support the incorporation of major pathological response as a surrogate endpoint for survival in future neoadjuvant trials of resectable lung cancers. Additional prospective studies are needed to confirm the validity and reproducibility of major pathological response within individual histological and molecular subgroups and with new drugs.