Prior radiotherapy is associated with longer survival times among patients administered pembrolizumab immunotherapy for non–small cell lung cancer (NSCLC), according to an analysis of data from the phase 1 KEYNOTE-001 trial Identifier: NCT01295827).1 The findings appear to bolster preclinical research linking radiotherapy to enhanced antitumor immune activity.

“Our data suggest that previous treatment with radiotherapy in patients with advanced NSCLC results in longer progression-free survival and overall survival with pembrolizumab treatment than is seen in patients who did not have previous radiotherapy, with an acceptable safety profile,” the researchers reported in The Lancet Oncology.

Pembrolizumab is a humanized monoclonal antibody that targets the PD-1 protein.

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The authors analyzed data for 97 patients enrolled in the KEYNOTE-001 pembrolizumab safety study, 42 of whom had previously undergone radiotherapy.

At a median follow-up of 32.5 months, progression-free survival (PFS) for those who had received radiation was longer than among the other patients (hazard ratio [HR] 0.56; 95% CI, 0.34-0.91; P = .019). Median PFS was 6.3 vs 2.0 months.

Overall survival (OS) was similarly improved among patients who had previously received radiotherapy (HR 0.58; 95% CI, 0.36-0.94; P = .026). Median OS was 10.7 vs 5.3 months.

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One patient in each group experienced grade 3 or worse treatment-related pulmonary toxicity.

The researchers called for additional clinical trials investigating radiotherapy followed by immune checkpoint blockade for patients with NSCLC. 


  1. Shaverdian N, Lisberg AE, Bornazyan K, et al. Previous radiotherapy and the clinical activity and toxicity of pembrolizumab in the treatment of non-small-cell lung cancer: a secondary analysis of the KEYNOTE-001 phase 1 trial. Lancet Oncol. 2017 May 24. doi: 10.1016/S1470-2045(17)30380-7 [Epub ahead of print]