Addition of Immune Checkpoint Inhibitors to Chemotherapy vs Chemotherapy Alone as First-Line Treatment in Extensive-Stage Small-Cell Lung Carcinoma: A Systematic Review and Meta-Analysis

Introduction

The addition of immune checkpoint inhibitors (ICIs) to conventional chemotherapy (CT) as first-line treatment improves survival in extensive-stage small-cell lung cancer (ES-SCLC). The aim of this meta-analysis was to determine the relative efficacy of first-line ICIs compared with CT in patients with ES-SCLC.

Methods

Two independent reviewers extracted relevant data according to PRISMA guidelines and assessed the risk of bias using the Cochrane Collaboration's risk-of-bias tool. Meta-analysis was conducted using random-effects models to calculate an average effect size for overall survival (OS), progression-free survival (PFS), and safety outcomes in the overall populations and clinically relevant subgroups.

Results

A literature search of PubMed and Embase was performed. Six randomized controlled clinical trials (IMpower133, CHECKMATE-451, CASPIAN, KEYNOTE-604, and phase II and III ipilimumab plus CT trials) with a total of 3757 patients were included. Compared with CT alone, ICIs plus CT showed a favourable effect on OS (hazard ratio [HR] 0.85; 95% confidence intervals [CI] 0.79–0.96) and PFS (HR 0.78; 95% CI 0.72–0.83) but a non-significant increase in the risk of experiencing any adverse event (relative risk, 1.05; 95% CI 0.99–1.11). The estimated HR for OS favoured ICI combinations in all planned subgroups according to age (< 65 years/≥ 65 years), sex (men/women), and ECOG performance status (0/1). Analysis by specific ICI revealed significant improvements in OS only for atezolizumab + CT (HR 1.36; 95% CI 1.09–1.69) and durvalumab + CT (HR 1.35; 95% CI 1.12–1.62) compared with CT alone.

Conclusion

Combining anti-programmed cell death ligand 1 antibodies with platinum/etoposide is a superior therapeutic approach compared to CT alone for the first-line treatment of patients with ES-SCLC.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40487-021-00182-0.

Durvalumab: A Review in Extensive-Stage SCLC

Durvalumab (IMFINZI^®), a fully human monoclonal antibody against programmed cell death-ligand 1 (PD-L1), is approved for use in combination with etoposide and either carboplatin or cisplatin for the first-line treatment of patients with extensive-stage small cell lung cancer (ES-SCLC). In the pivotal phase III CASPIAN trial in previously untreated adults with ES-SCLC, the addition of durvalumab to chemotherapy for up to 4 cycles followed by maintenance durvalumab was associated with a significantly longer overall survival and a favourable hazard ratio for progression-free survival compared with chemotherapy alone for up to 6 cycles. A higher proportion of patients in the durvalumab plus chemotherapy group had an objective response compared with the chemotherapy alone group. The efficacy of durvalumab was also sustained with longer follow-up. Durvalumab in combination with etoposide and either carboplatin or cisplatin had a manageable tolerability profile in patients with ES-SCLC. Given the available evidence, durvalumab in combination with etoposide and either carboplatin or cisplatin represents a valuable treatment option for the first-line treatment of patients with ES-SCLC, and is an accepted standard of care option in this setting.

Small cell lung cancer (SCLC) is the most aggressive form of lung cancer; extensive-stage (ES) disease, which accounts for about two-thirds of all SCLC, is associated with high relapse rates and a poor prognosis. Expression of programmed cell death-ligand 1 (PD-L1) on both tumour cells and tumour-associated immune cells is an adaptive immune response that helps tumour cells avoid detection and subsequent elimination by the immune system. Durvalumab (IMFINZI^®) is a fully human monoclonal antibody against PD-L1, which blocks the interaction of PD-L1 with its receptors, thus enhancing anti-tumour immune responses. When used in combination with chemotherapy (etoposide and either carboplatin or cisplatin) in adults with untreated ES-SCLC, durvalumab prolonged overall survival compared with chemotherapy alone; the improvements in overall survival were also maintained with additional follow-up. The tolerability profile of durvalumab in combination with chemotherapy was manageable in patients with ES-SCLC. Durvalumab in combination with chemotherapy is an effective and valuable treatment option for previously untreated patients with ES-SCLC.