Treatment that activates the immune system to kill tumors in extensive-stage small cell lung cancer

This trial looked at therapy that activates the immune system to kill cancerous tumors in patients with extensive stage small cell lung cancer (ES-CLC). The authors concluded pembrolizumab (Keytruda) is tolerable and a promising treatment for patients with heavily treated ES-SCLC.

Extensive-stage small cell lung cancer patients have poor survival rates because the cancer usually progresses past first-line chemotherapy treatment. Therefore more effective treatments are needed. Immune checkpoint inhibitors including pembrolizumab work by blocking a protein called PD-L1 present on tumors. This results in activating the immune system to kill the tumor. Pembrolizumab has been shown to be effective for other cancers including other types of lung cancers. Whether it would be an effective treatment for ES-SCLC remains to be seen.

This trial looked at the effectiveness and safety of pembrolizumab at treating patients with ES-SCLC with PD-L1 on tumors.

24 patients were included in this trial. These patients had all progressed past previous treatment for ES-SCLC. Patients were followed for an average of 9.8 months.

All patients had side effects. The most common were physical weakness (7 patients), fatigue (7 patients) and cough (6 patients). Other side effects included joint pain, diarrhea, insomnia, and rash. 

The objective response rate (percent of patients with tumor reduction or stable disease) was 33.3%. The average progression free survival (PFS, time from beginning trial until disease progression) was 1.9 months. The average PFS rate at 2 years post treatment was 23.8%. Average overall survival (OS, time from beginning trial until death from any cause) was 9.7 months. OS at 1 year after treatment was 37.7%.

The authors concluded that the toxicity levels associated with pembrolizumab were the same as previously reported levels. They also suggested the pembrolizumab is a promising treatment for patients with ES-SCLC that has progressed past initial treatments.

This study was funded by manufacturers of pembrolizumab.