Can biological drug pembrolizumab added to chemotherapy improve treatment results long-term for patients with non-small cell lung cancer?

This study examined if the addition of pembrolizumab (Keytruda) to chemotherapy with pemetrexed (Alimta) and platinum improved treatment results long-term for patients with advanced non-small-cell lung cancer (NSCLC). The authors found that patients who received pembrolizumab with chemotherapy had improved survival and similar side effects to chemotherapy alone.

Pembrolizumab is a drug that blocks cancer from turning off the immune system. Clinical trials have shown that it significantly improves treatment results for patients with NSCLC with or without chemotherapy.  Pemetrexed and platinum is a chemotherapy combination often used to treat patients with advanced (stage III or IV) NSCLC. Platinum drugs include carboplatin (Paraplatin) or cisplatin (Platinol). 

Pembrolizumab combined with pemetrexed and platinum drugs was shown to improve patients’ survival safely in the short term. It is unknown if this effect continues over the long term.

616 patients with advanced NSCLC were divided into two groups. 410 patients received pembrolizumab, pemetrexed, and platinum and 206 patients received a placebo and pemetrexed and platinum. Patients’ results were followed for 23.1 months on average.

Patients in the pembrolizumab group were 44% more likely to survive than patients in the placebo group. On average, patients in the pembrolizumab group survived for 22 months and patients in the placebo group survived for 10.7 months. It was estimated that after 24 months, 45.5% of the pembrolizumab group and 29.9% of the placebo group would survive.

Patients were 52% more likely to survive without cancer worsening in the pembrolizumab group than the placebo group. On average, patients in the pembrolizumab group survived for 9 months without cancer worsening compared to 4.9 months in the placebo group. It was estimated that after 24 months 20.5% of the pembrolizumab group and 1.5% of the placebo group would not have cancer progression.

48% of the pembrolizumab group and 19.4% of the placebo group responded to treatment (had a significant reduction in cancer). Pembrolizumab improved treatment results for patients with cancer spread to the brain or liver also.

71.9% of the pembrolizumab group and 66.8% of the placebo group developed serious side effects. 26.4% of the pembrolizumab group and 12.9% of the placebo group had allergic reactions to treatment.

The authors concluded that patients who had pembrolizumab added to pemetrexed-platinum chemotherapy had significantly improved outcomes compared to chemotherapy alone.

The manufacturer of pembrolizumab, Merck Sharp and Dohme, funded this study.