Can immune checkpoint inhibitors be used in the treatment of extensive-stage small cell lung cancer?

This article looked at the use of immune checkpoint inhibitors (ICIs) in the treatment of extensive-stage (ES) small cell lung cancer (SCLC). The authors found that the addition of atezolizumab (Tecentriq) or durvalumab (Imfinzi) to first-line platinum-based chemotherapy prolongs survival and improves the quality of life in patients with ES-SCLC. 

SCLC represents around 15% of all lung cancer diagnoses. Around 70% of SCLCs are diagnosed as ES. ES-SCLC is cancer that has spread beyond the lung, to the lymph node, other lung, or to other parts of the body.

ES-SCLC is usually treated effectively with chemotherapy. Despite this, patients usually experience a rapid spread of their cancer. Therefore, new therapies are needed for this type of cancer. Immune checkpoint inhibitors (ICIs) are immunotherapies. They block certain proteins on cancer cells that can weaken the immune response towards the cancer. Therefore, ICIs allow the immune cells to better detect and kill cancer cells. Previous studies have investigated the use of ICIs in SCLC. However, it is still unclear which ICIs work better in ES-SCLC.

The authors looked at 6 clinical trials that assessed ICI use plus chemotherapy as a first-line therapy for ES-SCLC. 

4 trials evaluated ICIs as first-line therapy. One trial showed that ipilimumab (Yervoy) plus chemotherapy as first-line therapy did not improve survival in patients with ES-SCLC. Another trial investigated the use of atezolizumab in combination with a platinum-based chemotherapy in 403 patients. Atezolizumab added platinum-based chemotherapy significantly improved survival (by 24%) compared to placebo at an average follow-up of 22.9 months.

The third trial evaluated durvalumab with or without tremelimumab (CP-675,206) added to platinum-based chemotherapy in 537 patients. Durvalumab in combination with platinum-based chemotherapy improved survival in patients with ES-SCLC compared to chemotherapy alone at an average follow-up of 25.1 months (by 25%). There was no benefit added with the addition of tremelimumab. 

The fourth trial investigated pembrolizumab (Keytruda) added to chemotherapy in 453 patients. It showed a slight improvement in overall survival with pembrolizumab added to chemotherapy compared to chemotherapy alone. However, this was not significant. There was a significantly higher response rate with pembrolizumab (70.6%) compared to placebo (61.8%) added to chemotherapy and a longer duration of response. 

The authors concluded that the addition of either atezolizumab or durvalumab to first-line platinum-based chemotherapy significantly improves overall survival and quality of life in patients with ES-SCLC.