The addition of Keytruda (pembrolizumab) to chemoradiotherapy appears to be safe and effective in patients with stage 3 unresectable non-small cell lung cancer (NSCLC), according to data published in JAMA Oncology.

“The cure rates for stage 3 non-small cell lung cancer had significant need for improvement beyond standard therapy with chemoradiation,” Dr. Salma Jabbour, a radiation oncologist at Rutgers Cancer Institute of New Jersey, said in an interview with CURE ®. “With the breakthrough that immunotherapy, PD-1 blockade, affords stage 4 lung cancer, we thought that incorporating immunotherapy into stage 3 lung cancer would be important.”

Keytruda is a selective humanized monoclonal antibody that blocks the interaction between programmed cell death 1 (PD-1) and its ligands, PD-L1 and PD-L2.

The phase 1, nonrandomized controlled trial comprised 21 patients who received one or more cycles of Keytruda from August 2016 to October 2018. Safety and toxicity of Keytruda along with chemoradiotherapy for patients with stage 3 NSCLC served as the primary endpoint.

Secondary endpoints included locoregional recurrence, distant metastasis-free survival, progression-free survival (the time from treatment to disease progression or worsening), overall survival and pneumonitis rates.

“We added immunotherapy to the first day of chemoradiation,” Jabbour said. “Shortly after our study started, immunotherapy became routine to administer after chemoradiation. After this finding, our study became more relevant, since it asked the question of whether earlier treatment with immunotherapy in stage 3 lung cancer would help patients.”

Nausea, fatigue and constipation (86% for all) were the most common all-cause side effects. Pneumonitis, a secondary endpoint, occurred in 33% of patients.

Median progression-free survival was 18.7 months. Six-month progression-free survival was 81% and 12-month progression-free survival was 69.7%.

The 12-month progression-free survival rate shown is promising as it represents an increase from the 55.7% 12-month progression-free survival rate seen in the PACIFIC study, the researchers wrote.

The median progression-free survival increased to 21 months in patients (n = 19) who received at least two doses of Keytruda. Median overall survival was 29.4 months. The 6-month overall survival was 95.2% and the 12-month overall survival rate was 85.2%.

The results demonstrate that immunotherapy can be delivered safely with chemoradiation and that the combination can be effective, Jabbour explained. Additionally, she noted how these results can influence further research.

“We anticipate that these results will provide the background for bigger studies that can change how we time immunotherapy and chemoradiation,” Jabbour said. “We believe these results can help to provide more hope to patients with stage 3 NSCLC.”